| Compensation and Retirement Disclosure [Abstract] | Period [Axis] |
|---|
2016-01-01 - 2016-12-31 |
|---|
Compensation and Retirement Disclosure [Abstract] | |
Schedule of reconciliation of the changes in the benefit obligations | The following tables provide a reconciliation of the changes in the benefit obligations, fair value of plan assets and the underfunded status for the Company’s Defined Benefit Pension, Post-Retirement Medical, and Supplemental Executive Retirement plans: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit Pension Plan | | Post-Retirement Medical Plan | | Supplemental Executive Retirement Plan | | Total | | | Year Ended December 31, | | Year Ended December 31, | | Year Ended December 31, | | Year Ended December 31, | | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | Change in projected benefit obligation: | | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| Benefit obligation, January 1 | | $ | 560,817 |
| | $ | 583,080 |
| | $ | 16,637 |
| | $ | 12,782 |
| | $ | 43,858 |
| | $ | 55,832 |
| | $ | 621,312 |
| | $ | 651,694 |
| Service cost | | (1,403 | ) | | 12,851 |
| | 1,246 |
| | 1,042 |
| | 294 |
| | 282 |
| | 137 |
| | 14,175 |
| Interest cost | | 25,263 |
| | 23,987 |
| | 713 |
| | 560 |
| | 1,775 |
| | 2,122 |
| | 27,751 |
| | 26,669 |
| Actuarial (gain) loss | | 24,928 |
| | (42,863 | ) | | 1,408 |
| | 3,360 |
| | 1,911 |
| | (9,504 | ) | | 28,247 |
| | (49,007 | ) | Regular benefits paid | | (17,315 | ) | | (16,238 | ) | | (973 | ) | | (1,446 | ) | | (3,337 | ) | | (4,874 | ) | | (21,625 | ) | | (22,558 | ) | Acquisition | | — |
| | — |
| | — |
| | 339 |
| | — |
| | — |
| | — |
| | 339 |
| Benefit obligation, December 31 | | $ | 592,290 |
| | $ | 560,817 |
| | $ | 19,031 |
| | $ | 16,637 |
| | $ | 44,501 |
| | $ | 43,858 |
| | $ | 655,822 |
| | $ | 621,312 |
| Accumulated benefit obligation | | $ | 575,024 |
| | $ | 544,011 |
| | $ | 19,031 |
| | $ | 16,637 |
| | $ | 43,098 |
| | $ | 42,182 |
| | $ | 637,153 |
| | $ | 602,830 |
|
|
Schedule of fair value of plan assets | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit
Pension Plan | | Post-Retirement
Medical Plan | | Supplemental Executive
Retirement Plan | | Total | | | Year Ended December 31, | | Year Ended December 31, | | Year Ended December 31, | | Year Ended December 31, | | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | Change in plan assets: | | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| Value of plan assets, January 1 | | $ | 427,131 |
| | $ | 443,962 |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | 427,131 |
| | $ | 443,962 |
| Actual return on plan assets | | 43,271 |
| | (593 | ) | | — |
| | — |
| | — |
| | — |
| | 43,271 |
| | (593 | ) | Employer contributions | | — |
| | — |
| | 973 |
| | 1,446 |
| | 3,337 |
| | 4,874 |
| | 4,310 |
| | 6,320 |
| Benefits paid | | (17,315 | ) | | (16,238 | ) | | (973 | ) | | (1,446 | ) | | (3,337 | ) | | (4,874 | ) | | (21,625 | ) | | (22,558 | ) | Value of plan assets, December 31 | | $ | 453,087 |
| | $ | 427,131 |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | 453,087 |
| | $ | 427,131 |
|
|
Schedule of fair value of plan assets and the underfunded status | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit
Pension Plan | | Post-Retirement
Medical Plan | | Supplemental Executive
Retirement Plan | | Total | | | December 31, | | December 31, | | December 31, | | December 31, | | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | Under funded status at December 31 | | $ | (139,203 | ) | | $ | (133,686 | ) | | $ | (19,031 | ) | | $ | (16,637 | ) | | $ | (44,501 | ) | | $ | (43,858 | ) | | $ | (202,735 | ) | | $ | (194,181 | ) |
|
Schedule of amounts recognized in the consolidated balance sheets | The following table presents amounts recognized in the consolidated balance sheets for the Company’s Defined Benefit Pension, Post-Retirement Medical, and Supplemental Executive Retirement plans: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit
Pension Plan | | Post-Retirement
Medical Plan | | Supplemental Executive
Retirement Plan | | Total | | | December 31, | | December 31, | | December 31, | | December 31, | | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | | 2016 | | 2015 | Amounts recognized in consolidated balance sheets: | | |
| | |
| | |
| | |
| | |
| | |
| | |
| | |
| Other liabilities | | $ | (139,203 | ) | | $ | (133,686 | ) | | $ | (19,031 | ) | | $ | (16,637 | ) | | $ | (44,501 | ) | | $ | (43,858 | ) | | $ | (202,735 | ) | | $ | (194,181 | ) | Accumulated other comprehensive income (loss) | | (133,055 | ) | | (139,316 | ) | | 5,715 |
| | 8,540 |
| | (2,360 | ) | | (890 | ) | | (129,700 | ) | | (131,666 | ) |
|
Schedule of amounts recognized in AOCI that have not yet been recognized as components of net periodic benefit costs | The following table provides information regarding amounts in AOCI that have not yet been recognized as components of net periodic benefit cost at December 31, 2016: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit
Pension Plan | | Post-Retirement
Medical Plan | | Supplemental Executive
Retirement Plan | | Total | | | Gross | | Net of tax | | Gross | | Net of tax | | Gross | | Net of tax | | Gross | | Net of tax | Net gain (loss) | | $ | (133,055 | ) | | $ | (86,486 | ) | | $ | 5,091 |
| | $ | 3,309 |
| | $ | (660 | ) | | $ | (429 | ) | | $ | (128,624 | ) | | $ | (83,606 | ) | Net prior service (cost) credit | | — |
| | — |
| | 624 |
| | 406 |
| | (1,700 | ) | | (1,105 | ) | | (1,076 | ) | | (699 | ) | | | $ | (133,055 | ) | | $ | (86,486 | ) | | $ | 5,715 |
| | $ | 3,715 |
| | $ | (2,360 | ) | | $ | (1,534 | ) | | $ | (129,700 | ) | | $ | (84,305 | ) |
|
Schedule of information regarding amounts in AOCI that are expected to be recognized as components of net periodic benefit costs during the next fiscal year | The following table provides information regarding amounts in AOCI that are expected to be recognized as components of net periodic benefit costs during the year ended December 31, 2017:
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Defined Benefit
Pension Plan | | Post-Retirement
Medical Plan | | Supplemental Executive
Retirement Plan | | Total | | | Gross | | Net of tax | | Gross | | Net of tax | | Gross | | Net of tax | | Gross | | Net of tax | Net gain (loss) | | $ | (8,799 | ) | | $ | (5,719 | ) | | $ | 210 |
| | $ | 137 |
| | $ | 54 |
| | $ | 35 |
| | $ | (8,535 | ) | | $ | (5,547 | ) | Prior service (cost) credit | | — |
| | — |
| | 453 |
| | 294 |
| | (501 | ) | | (326 | ) | | (48 | ) | | (32 | ) | | | $ | (8,799 | ) | | $ | (5,719 | ) | | $ | 663 |
| | $ | 431 |
| | $ | (447 | ) | | $ | (291 | ) | | $ | (8,583 | ) | | $ | (5,579 | ) |
|
Schedule of expected benefit payments | The expected benefit payments for the Company’s Defined Benefit Pension, Post-Retirement Medical, and Supplemental Executive Retirement plans for the years indicated are as follows: | | | | | | | | | | | | | | | | Defined Benefit Pension Plan | | Post-Retirement Medical Plan | | Supplemental Executive Retirement Plan | 2017 | | $ | 16,600 |
| | $ | 856 |
| | $ | 3,435 |
| 2018 | | 20,029 |
| | 843 |
| | 2,775 |
| 2019 | | 21,231 |
| | 917 |
| | 2,460 |
| 2020 | | 22,694 |
| | 946 |
| | 2,438 |
| 2021 | | 24,820 |
| | 1,028 |
| | 2,400 |
| 2022 through 2026 | | 154,223 |
| | 6,776 |
| | 27,188 |
|
|
Schedule of net periodic (benefit) cost | Net periodic (benefit) cost of the Defined Benefit Pension, Post-Retirement Medical, and Supplemental Executive Retirement plans included in general insurance expenses in the accompanying consolidated statements of income includes the following components: | | | | | | | | | | | | | | | | Defined Benefit Pension Plan | | | Year Ended December 31, | | | 2016 | | 2015 | | 2014 | Components of net periodic cost: | | |
| | |
| | |
| Service cost | | $ | (1,403 | ) | | $ | 12,851 |
| | $ | 4,952 |
| Interest cost | | 25,263 |
| | 23,987 |
| | 23,068 |
| Expected return on plan assets | | (22,339 | ) | | (28,345 | ) | | (29,288 | ) | Amortization of unrecognized prior service cost | | — |
| | 13 |
| | 51 |
| Amortization of loss from earlier periods | | 10,260 |
| | 12,398 |
| | 2,898 |
| Net periodic cost | | $ | 11,781 |
| | $ | 20,904 |
| | $ | 1,681 |
|
| | | | | | | | | | | | | | | | Post-Retirement Medical Plan | | | Year Ended December 31, | | | 2016 | | 2015 | | 2014 | Components of net periodic benefit: | | |
| | |
| | |
| Service cost | | $ | 1,246 |
| | $ | 1,042 |
| | $ | 985 |
| Interest cost | | 713 |
| | 560 |
| | 574 |
| Amortization of unrecognized prior service benefit | | (1,102 | ) | | (1,640 | ) | | (1,706 | ) | Amortization of gain from earlier periods | | (317 | ) | | (511 | ) | | (450 | ) | Net periodic benefit | | $ | 540 |
| | $ | (549 | ) | | $ | (597 | ) |
| | | | | | | | | | | | | | | | Supplemental Executive Retirement Plan | | | Year Ended December 31, | | | 2016 | | 2015 | | 2014 | Components of net periodic cost: | | |
| | |
| | |
| Service cost | | $ | 294 |
| | $ | 282 |
| | $ | 586 |
| Interest cost | | 1,775 |
| | 2,122 |
| | 2,528 |
| Amortization of unrecognized prior service cost | | 501 |
| | 933 |
| | 4,844 |
| Amortization of loss from earlier periods | | (61 | ) | | 663 |
| | 282 |
| Settlement | | — |
| | — |
| | 1,857 |
| Net periodic cost | | $ | 2,509 |
| | $ | 4,000 |
| | $ | 10,097 |
|
|
Schedule of weighted average interest rate assumptions used in determining benefit obligations | The following tables present the assumptions used in determining benefit obligations of the Defined Benefit Pension, Post-Retirement Medical, and the Supplemental Executive Retirement plans: | | | | | | | | | | Defined Benefit Pension Plan | | | December 31, | | | 2016 | | 2015 | Discount rate | | 4.20 | % | | 4.55 | % | Rate of compensation increase | | 4.47 | % | | 4.47 | % |
| | | | | | | | | | Post-Retirement Medical Plan | | | December 31, | | | 2016 | | 2015 | Discount rate | | 4.05 | % | | 4.31 | % | Initial health care cost trend | | 6.75 | % | | 7.00 | % | Ultimate health care cost trend | | 5.00 | % | | 5.00 | % | Year ultimate trend is reached | | 2024 |
| | 2024 |
|
| | | | | | | | | | Supplemental Executive Retirement Plan | | | December 31, | | | 2016 | | 2015 | Discount rate | | 3.80 | % | | 4.22 | % | Rate of compensation increase | | 4.00 | % | | 4.00 | % |
|
Schedule of weighted average interest rate assumptions used in determining the net periodic (benefit) cost | The following tables present the assumptions used in determining the net periodic (benefit) cost of the Defined Benefit Pension, Post-Retirement Medical, and the Supplemental Executive Retirement plans: | | | | | | | | | | Defined Benefit Pension Plan | | | Year Ended December 31, | | | 2016 | | 2015 | Discount rate | | 4.55 | % | | 4.17 | % | Expected return on plan assets | | 6.00 | % | | 6.50 | % | Rate of compensation increase | | 4.47 | % | | 4.47 | % |
| | | | | | | | | | Post-Retirement Medical Plan | | | Year Ended December 31, | | | 2016 | | 2015 | Discount rate | | 4.31 | % | | 3.94 | % | Initial health care cost trend | | 7.00 | % | | 6.50 | % | Ultimate health care cost trend | | 5.00 | % | | 5.00 | % | Year ultimate trend is reached | | 2024 |
| | 2018 |
|
| | | | | | | | | | Supplemental Executive Retirement Plan | | | Year Ended December 31, | | | 2016 | | 2015 | Discount rate | | 4.22 | % | | 3.99 | % | Rate of compensation increase | | 4.00 | % | | 4.00 | % |
|
Schedule of effect of one-percentage-point change in assumed healthcare cost trend rates | The following table presents the impact on the Post-Retirement Medical Plan that a one-percentage-point change in assumed health care cost trend rates would have on the following: | | | | | | | | | | | | One percentage point increase | | One percentage
point decrease | Increase (decrease) on total service and interest cost on components | | $ | 322 |
| | $ | (269 | ) | Increase (decrease) on post-retirement benefit obligation | | 2,430 |
| | (2,083 | ) |
|
Schedule of investment of defined benefit pension plan assets | The following table presents how the Company’s Defined Benefit Pension Plan assets are invested: | | | | | | | | | | December 31, | | | 2016 | | 2015 | Equity securities | | 45 | % | | 67 | % | Debt securities | | 39 | % | | 31 | % | Other | | 16 | % | | 2 | % | Total | | 100 | % | | 100 | % |
|
Schedule of defined benefit retirement plan assets measured at fair value on a recurring basis | The following tables present information about the Defined Benefit Retirement Plan’s assets measured at fair value on a recurring basis and indicates the fair value hierarchy of the valuation approach utilized to determine such fair value: | | | | | | | | | | | | | | | | | | | | Defined benefit plan assets measured at fair value on a recurring basis | | | December 31, 2016 | | | Quoted prices in active markets for identical assets (Level 1) | | Significant other observable inputs (Level 2) | | Significant unobservable inputs (Level 3) | | Total | Common collective trust funds: (1) | | |
| | |
| | |
| | |
| Equity index funds | | $ | — |
| | $ | — |
| | $ | — |
| | $ | 34,578 |
| Midcap index funds | | — |
| | — |
| | — |
| | 35,330 |
| World equity index funds | | — |
| | — |
| | — |
| | 44,235 |
| U.S. equity market funds | | — |
| | — |
| | — |
| | 45,614 |
| International equity funds | | — |
| | — |
| | — |
| | 11,143 |
| Total common collective trust funds | | — |
| | — |
| | — |
| | 170,900 |
| Fixed maturity investments: | | |
| | |
| | |
| | |
| U.S. government direct obligations and agencies | | — |
| | 5,672 |
| | — |
| | 5,672 |
| Obligations of U.S. states and their municipalities | | — |
| | 18,670 |
| | — |
| | 18,670 |
| Corporate debt securities | | — |
| | 141,102 |
| | 1,316 |
| | 142,418 |
| Asset-backed securities | | — |
| | 7,828 |
| | — |
| | 7,828 |
| Commercial mortgage-backed securities | | — |
| | 2,884 |
| | — |
| | 2,884 |
| Total fixed maturity investments | | — |
| | 176,156 |
| | 1,316 |
| | 177,472 |
| Equity investments: | | | | | | | | | Fixed income mutual funds | | 21,321 |
| | — |
| | — |
| | 21,321 |
| Equity mutual funds | | 11,106 |
| | — |
| | — |
| | 11,106 |
| Preferred stock | | 640 |
| | — |
| | — |
| | 640 |
| Total equity investments | | 33,067 |
| | — |
| | — |
| | 33,067 |
| Limited partnership investments (1) | | — |
| | — |
| | — |
| | 7,022 |
| Money market funds | | 62,883 |
| | — |
| | — |
| | 62,883 |
| Total defined benefit plan assets | | $ | 95,950 |
| | $ | 176,156 |
| | $ | 1,316 |
| | $ | 451,344 |
|
(1) Fair values of Common collective trust funds and Limited partnership investments are estimated using net asset value per unit as a practical expedient which are excluded from the disclosure requirement to classify amounts in the fair value hierarchy in connection with the adoption of ASU 2015-07. | | | | | | | | | | | | | | | | | | | | Defined benefit plan assets measured at fair value on a recurring basis | | | December 31, 2015 | | | Quoted prices in active markets for identical assets (Level 1) | | Significant other observable inputs (Level 2) | | Significant unobservable inputs (Level 3) | | Total | Common collective trust funds: (1) | | |
| | |
| | |
| | |
| Equity index funds | | $ | — |
| | $ | — |
| | $ | — |
| | $ | 94,751 |
| Midcap index funds | | — |
| | — |
| | — |
| | 88,267 |
| World equity index funds | | — |
| | — |
| | — |
| | 8,511 |
| U.S. equity market funds | | — |
| | — |
| | — |
| | 94,471 |
| Total common collective trust funds | | — |
| | — |
| | — |
| | 286,000 |
| Fixed maturity investments: | | |
| | |
| | |
| | |
| U.S. government direct obligations and agencies | | — |
| | 6,753 |
| | — |
| | 6,753 |
| Obligations of U.S. states and their municipalities | | — |
| | 19,074 |
| | — |
| | 19,074 |
| Corporate debt securities | | — |
| | 93,811 |
| | — |
| | 93,811 |
| Asset-backed securities | | — |
| | 8,149 |
| | — |
| | 8,149 |
| Commercial mortgage-backed securities | | — |
| | 2,926 |
| | — |
| | 2,926 |
| Total fixed maturity investments | | — |
| | 130,713 |
| | — |
| | 130,713 |
| Preferred stock | | 280 |
| | — |
| | — |
| | 280 |
| Limited partnership investments (1) | | — |
| | — |
| | — |
| | 7,654 |
| Money market funds | | 2,484 |
| | — |
| | — |
| | 2,484 |
| Total defined benefit plan assets | | $ | 2,764 |
| | $ | 130,713 |
| | $ | — |
| | $ | 427,131 |
|
(1) Fair values of Common collective trust funds and Limited partnership investments are estimated using net asset value per unit as a practical expedient which are excluded from the disclosure requirement to classify amounts in the fair value hierarchy in connection with the adoption of ASU 2015-07. |
Schedule of defined benefit retirement plan assets measured at fair value on a recurring basis for which Level 3 inputs are utilized | The following tables present additional information about assets of the Defined Benefit Retirement Plan measured at fair value on a recurring basis and for which the Company has utilized Level 3 inputs to determine fair value: | | | | | | | | | | | | Recurring Level 3 financial assets | | | Corporate debt securities | | | Year Ended December 31, | | | 2016 | | 2015 | Balance, January 1 | | $ | — |
| | $ | — |
| Actual return on plan assets | | 54 |
| | — |
| Settlements | | (213 | ) | | — |
| Transfers into Level 3 (1) | | 1,475 |
| | — |
| Balance, December 31 | | $ | 1,316 |
| | $ | — |
|
(1) Transfers into Level 3 are due primarily to decreased observability of inputs in valuation methodologies. |
Schedule of targets for the allocation of invested Defined Benefit Pension Plan assets | The following table presents the ranges the Company targets for the allocation of invested Defined Benefit Pension Plan assets at December 31, 2017: | | | | | | | December 31, 2017 | Equity securities | | 30 | % | Debt securities | | 52 | % | Other | | 18 | % | Total | | 100 | % |
|