| Compensation and Retirement Disclosure [Abstract] | Period [Axis] |
|---|
2016-01-01 - 2016-12-31 |
|---|
Compensation and Retirement Disclosure [Abstract] | |
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract] | |
Schedule of defined benefit plans | The components of pension and other postretirement benefit expense for the Company’s defined benefit plans included the following: | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | (In millions) | | 2016 | | 2015 | | 2014 | | 2016 | | 2015 | | 2014 | Service cost—benefits earned during the year | | $ | 20.6 |
| | $ | 22.8 |
| | $ | 29.4 |
| | $ | 2.6 |
| | $ | 2.7 |
| | $ | 2.9 |
| Interest cost on benefits earned in prior years | | 125.4 |
| | 121.0 |
| | 133.6 |
| | 16.0 |
| | 17.9 |
| | 24.0 |
| Expected return on plan assets | | (148.7 | ) | | (168.3 | ) | | (184.2 | ) | | (0.1 | ) | | (0.1 | ) | | (0.3 | ) | Amortization of prior service cost (credit) | | 1.3 |
| | 1.3 |
| | 2.3 |
| | (1.7 | ) | | 4.9 |
| | (3.0 | ) | Amortization of net actuarial loss | | 65.4 |
| | 60.4 |
| | 74.0 |
| | 9.6 |
| | 14.6 |
| | 14.1 |
| Curtailment (gain) loss | | — |
| | — |
| | 0.5 |
| | — |
| | — |
| | (25.5 | ) | Termination benefits | | 1.1 |
| | — |
| | 0.3 |
| | 2.3 |
| | — |
| | — |
| Total retirement benefit expense | | $ | 65.1 |
| | $ | 37.2 |
| | $ | 55.9 |
| | $ | 28.7 |
| | $ | 40.0 |
| | $ | 12.2 |
|
|
Schedule of assumptions used | Actuarial assumptions used to develop the components of defined benefit pension expense and other postretirement benefit expense were as follows: | | | | | | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | | | 2016 | | 2015 | | 2014 | | 2016 | | 2015 | | 2014 | Discount rate (a) | | 4.65 | % | | 4.25 | % | | 5.15 | % | | 4.05 - 4.50% |
| | 4.10 | % | | 5.15 | % | Rate of increase in future compensation levels | | 3.0 - 3.50% |
| | 3.0 - 3.50% |
| | 3.0 - 3.50% |
| | — |
| | — |
| | — |
| Expected long-term rate of return on assets | | 8.00 | % | | 8.00 | % | | 8.25 | % | | 4.0 | % | | 4.0 | % | | 8.3 | % |
| | (a) | Other post-retirement benefits expense for 2016 was initially measured at a 4.50% discount rate. A portion of the obligation was remeasured using a 4.05% discount rate as of March 1, 2016, following the new USW labor agreement discussed above. |
|
Schedule of assumptions used for year end valuation | Actuarial assumptions used for the valuation of defined benefit pension and other postretirement benefit obligations at the end of the respective periods were as follows: | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | | | 2016 | | 2015 | | 2016 | | 2015 | Discount rate | | 4.45 | % | | 4.65 | % | | 4.35 | % | | 4.50 | % | Rate of increase in future compensation levels | | 1.0 | % | | 3.0 - 3.5% |
| | — |
| | — |
|
|
Schedule of changes in projected benefit obligations | A reconciliation of the funded status for the Company’s defined benefit pension and other postretirement benefit plans at December 31, 2016 and 2015 was as follows: | | | | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | (In millions) | | 2016 | | 2015 | | 2016 | | 2015 | Change in benefit obligations: | | | | | | | | | Benefit obligation at beginning of year | | $ | 2,805.9 |
| | $ | 2,953.9 |
| | $ | 400.8 |
| | $ | 466.1 |
| Service cost | | 20.6 |
| | 22.8 |
| | 2.6 |
| | 2.7 |
| Interest cost | | 125.4 |
| | 121.0 |
| | 16.0 |
| | 17.9 |
| Benefits paid | | (255.4 | ) | | (207.4 | ) | | (47.7 | ) | | (53.4 | ) | Subsidy paid | | — |
| | — |
| | 0.8 |
| | 0.7 |
| Participant contributions | | 0.2 |
| | 0.3 |
| | — |
| | — |
| Effect of currency rates | | (17.3 | ) | | (4.8 | ) | | — |
| | — |
| Net actuarial (gains) losses – discount rate change | | 57.8 |
| | (124.4 | ) | | 4.6 |
| | (14.1 | ) | – other | | (3.9 | ) | | 44.5 |
| | (2.1 | ) | | (19.1 | ) | Plan curtailments | | (6.7 | ) | | — |
| | — |
| | — |
| Plan amendments | | — |
| | — |
| | (22.5 | ) | | — |
| Special termination benefits | | 1.1 |
| | — |
| | 2.3 |
| | — |
| Benefit obligation at end of year | | $ | 2,727.7 |
| | $ | 2,805.9 |
| | $ | 354.8 |
| | $ | 400.8 |
|
|
Schedule of changes in fair value of plan assets | | | | | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | (In millions) | | 2016 | | 2015 | | 2016 | | 2015 | Change in plan assets: | | | | | | | | | Fair value of plan assets at beginning of year | | $ | 1,962.3 |
| | $ | 2,204.4 |
| | $ | 1.8 |
| | $ | 2.9 |
| Actual returns on plan assets and plan expenses | | 79.7 |
| | (41.1 | ) | | (0.8 | ) | | (1.0 | ) | Employer contributions | | 125.1 |
| | 10.3 |
| | — |
| | — |
| Participant contributions | | 0.2 |
| | 0.3 |
| | — |
| | — |
| Effect of currency rates | | (17.3 | ) | | (4.2 | ) | | — |
| | — |
| Benefits paid | | (255.4 | ) | | (207.4 | ) | | (0.3 | ) | | (0.1 | ) | Fair value of plan assets at end of year | | $ | 1,894.6 |
| | $ | 1,962.3 |
| | $ | 0.7 |
| | $ | 1.8 |
|
|
Schedule of amounts recognized in balance sheet | | | | | | | | | | | | | | | | | | | Amounts recognized in the consolidated balance sheets: | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | | | 2016 | | 2015 | | 2016 | | 2015 | Current liabilities | | $ | (5.2 | ) | | $ | (9.8 | ) | | $ | (36.4 | ) | | $ | (39.8 | ) | Noncurrent liabilities | | (827.9 | ) | | (833.8 | ) | | (317.7 | ) | | (359.2 | ) | Total amount recognized | | $ | (833.1 | ) | | $ | (843.6 | ) | | $ | (354.1 | ) | | $ | (399.0 | ) |
|
Schedule of amounts recognized in other comprehensive income | Changes to accumulated other comprehensive loss related to pension and other postretirement benefit plans in 2016 and 2015 were as follows: | | | | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | (In millions) | | 2016 | | 2015 | | 2016 | | 2015 | Beginning of year accumulated other comprehensive loss | | $ | (1,418.2 | ) | | $ | (1,352.1 | ) | | $ | (101.4 | ) | | $ | (152.9 | ) | Amortization of net actuarial loss | | 65.4 |
| | 60.4 |
| | 9.6 |
| | 14.6 |
| Amortization of prior service cost (credit) | | 1.3 |
| | 1.3 |
| | (1.7 | ) | | 4.9 |
| Remeasurements | | (111.2 | ) | | (127.8 | ) | | 19.1 |
| | 32.0 |
| End of year accumulated other comprehensive loss | | $ | (1,462.7 | ) | | $ | (1,418.2 | ) | | $ | (74.4 | ) | | $ | (101.4 | ) | Net change in accumulated other comprehensive loss | | $ | (44.5 | ) | | $ | (66.1 | ) | | $ | 27.0 |
| | $ | 51.5 |
|
|
Schedule of net periodic benefit cost not yet recognized | Amounts included in accumulated other comprehensive loss at December 31, 2016 and 2015 were as follows: | | | | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | (In millions) | | 2016 | | 2015 | | 2016 | | 2015 | Prior service (cost) credit | | $ | (2.3 | ) | | $ | (3.6 | ) | | $ | 14.6 |
| | $ | (6.9 | ) | Net actuarial loss | | (1,460.4 | ) | | (1,414.6 | ) | | (89.0 | ) | | (94.5 | ) | Accumulated other comprehensive loss | | (1,462.7 | ) | | (1,418.2 | ) | | (74.4 | ) | | (101.4 | ) | Deferred tax effect | | 543.4 |
| | 529.9 |
| | 28.2 |
| | 38.5 |
| Accumulated other comprehensive loss, net of tax | | $ | (919.3 | ) | | $ | (888.3 | ) | | $ | (46.2 | ) | | $ | (62.9 | ) |
|
Schedule of amounts in accumulated other comprehensive income to be recognized | Amounts in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost in 2017 are: | | | | | | | | | | | | | | (In millions) | | Pension Benefits | | Other Postretirement Benefits | | Total | Amortization of prior service cost (credit) | | $ | 1.3 |
| | $ | (2.9 | ) | | $ | (1.6 | ) | Amortization of net actuarial loss | | 62.6 |
| | 9.0 |
| | 71.6 |
| Amortization of accumulated other comprehensive loss | | $ | 63.9 |
| | $ | 6.1 |
| | $ | 70.0 |
|
|
Schedule of accumulated benefit obligations in excess of fair value of plan assets | Additional information for pension plans with accumulated benefit obligations in excess of plan assets: | | | | | | | | | | | | Pension Benefits | (In millions) | | 2016 | | 2015 | Projected benefit obligation | | $ | 2,727.7 |
| | $ | 2,805.9 |
| Accumulated benefit obligation | | $ | 2,710.7 |
| | $ | 2,767.0 |
| Fair value of plan assets | | $ | 1,894.6 |
| | $ | 1,962.3 |
|
|
Schedule of expected benefit payments | The following table summarizes expected benefit payments from the Company’s various pension and other postretirement defined benefit plans through 2026, and also includes estimated Medicare Part D subsidies projected to be received during this period based on currently available information. | | | | | | | | | | | | | | (In millions) | | Pension Benefits | | Other Postretirement Benefits | | Medicare Part D Subsidy | 2017 | | $ | 194.7 |
| | $ | 37.1 |
| | $ | 1.0 |
| 2018 | | 191.8 |
| | 35.1 |
| | 1.0 |
| 2019 | | 189.6 |
| | 32.6 |
| | 0.9 |
| 2020 | | 188.3 |
| | 30.6 |
| | 0.9 |
| 2021 | | 186.5 |
| | 29.1 |
| | 0.8 |
| 2022 - 2026 | | 901.5 |
| | 121.8 |
| | 3.5 |
|
|
Schedule of effect of one-percentage-point change in assumed health care cost trend rates | A one percentage point change in assumed health care cost trend rates would have the following effects: | | | | | | | | | | (In millions) | | One Percentage Point Increase | | One Percentage Point Decrease | Effect on total of service and interest cost components for the year ended December 31, 2016 | | $ | 0.3 |
| | $ | (0.3 | ) | Effect on other postretirement benefit obligation at December 31, 2016 | | $ | 6.9 |
| | $ | (6.1 | ) |
|
Schedule of allocation of plan assets | The fair values of the Company’s pension plan assets are determined using net asset value (NAV) as a practical expedient, or by information categorized in the fair value hierarchy level based on the inputs used to determine fair value, as further discussed in Note 11. The fair values at December 31, 2016 were as follows: | | | | | | | | | | | | | | | | | | | | | | (In millions) | | | | | | Quoted Prices in Active Markets for Identical Assets | | Significant Observable Inputs | | Significant Unobservable Inputs | Asset category | | Total | | NAV | | (Level 1) | | (Level 2) | | (Level 3) | Equity securities: | | | | | | | | | | | ATI common stock | | $ | 47.1 |
| | $ | — |
| | $ | 47.1 |
| | $ | — |
| | $ | — |
| Other U.S. equities | | 311.1 |
| | 204.0 |
| | 107.1 |
| | — |
| | — |
| International equities | | 375.7 |
| | 339.2 |
| | 36.5 |
| | — |
| | — |
| Global debt securities and cash: | | | | | | | | | | | Fixed income and cash equivalents | | 412.2 |
| | 82.3 |
| | 0.5 |
| | 329.2 |
| | 0.2 |
| Floating rate | | 164.0 |
| | 64.9 |
| | — |
| | — |
| | 99.1 |
| Private equity | | 204.1 |
| | 204.1 |
| | — |
| | — |
| | — |
| Hedge funds | | 283.9 |
| | 283.9 |
| | — |
| | — |
| | — |
| Real estate and other | | 96.5 |
| | 91.5 |
| | — |
| | 5.0 |
| | — |
| Total assets | | $ | 1,894.6 |
| | $ | 1,269.9 |
| | $ | 191.2 |
| | $ | 334.2 |
| | $ | 99.3 |
|
The fair values of the Company’s pension plan assets at December 31, 2015 were as follows: | | | | | | | | | | | | | | | | | | | | | | (In millions) | | | | | | Quoted Prices in Active Markets for Identical Assets | | Significant Observable Inputs | | Significant Unobservable Inputs | Asset category | | Total | | NAV | | (Level 1) | | (Level 2) | | (Level 3) | Equity securities: | | | | | | | | | | | ATI common stock | | $ | 33.2 |
| | $ | — |
| | $ | 33.2 |
| | $ | — |
| | $ | — |
| Other U.S. equities | | 522.0 |
| | 267.9 |
| | 254.1 |
| | — |
| | — |
| International equities | | 239.8 |
| | 239.8 |
| | — |
| | — |
| | — |
| Global debt securities and cash: | | | | | | | | | | | Fixed income and cash equivalents | | 369.7 |
| | 249.0 |
| | 0.2 |
| | 120.2 |
| | 0.3 |
| Floating rate | | 358.0 |
| | 52.7 |
| | — |
| | — |
| | 305.3 |
| Private equity | | 201.2 |
| | 201.2 |
| | — |
| | — |
| | — |
| Hedge funds | | 51.9 |
| | 51.9 |
| | — |
| | — |
| | — |
| Real estate and other | | 186.5 |
| | 180.6 |
| | — |
| | 5.9 |
| | — |
| Total assets | | $ | 1,962.3 |
| | $ | 1,243.1 |
| | $ | 287.5 |
| | $ | 126.1 |
| | $ | 305.6 |
|
|
Changes in fair value of level 3 plan investments | Changes in the fair value of Level 3 pension plan assets for the year ended December 31, 2016 were as follows: | | | | | | | | | | | | | | | | | | | | | | (In millions) | | January 1, 2016 Balance | | Net Realized and Unrealized Gains (Losses) | | Net Purchases, Issuances and Settlements | | Net Transfers Into (Out Of) Level 3 | | December 31, 2016 Balance | Global debt securities and cash: | | | | | | | | | | | Fixed income and cash equivalents | | $ | 0.3 |
| | $ | — |
| | $ | (0.1 | ) | | $ | — |
| | $ | 0.2 |
| Floating rate debt | | 305.3 |
| | 12.1 |
| | (218.3 | ) | | — |
| | 99.1 |
| Total | | $ | 305.6 |
| | $ | 12.1 |
| | $ | (218.4 | ) | | $ | — |
| | $ | 99.3 |
|
Changes in the fair value of Level 3 pension plan assets for the year ended December 31, 2015 were as follows: | | | | | | | | | | | | | | | | | | | | | | (In millions) | | January 1, 2015 Balance | | Net Realized and Unrealized Gains (Losses) | | Net Purchases, Issuances and Settlements | | Net Transfers Into (Out Of) Level 3 | | December 31, 2015 Balance | Global debt securities and cash: | | | | | | | | | | | Fixed income and cash equivalents | | $ | 0.3 |
| | $ | — |
| | $ | — |
| | $ | — |
| | $ | 0.3 |
| Floating rate debt | | 361.0 |
| | 4.4 |
| | (60.1 | ) | | — |
| | 305.3 |
| Total | | $ | 361.3 |
| | $ | 4.4 |
| | $ | (60.1 | ) | | $ | — |
| | $ | 305.6 |
|
|
Schedule of target asset allocations for pension plans | The target asset allocations for pension plans for 2017, by major investment category, are: | | | | Asset category | | Target asset allocation range | Equity securities: | | | U. S. equities | | 18% - 40% | International equities | | 10% - 30% | Global debt securities and cash | | 15% - 40% | Private equity | | 0% - 15% | Hedge funds | | 10% - 20% | Real estate and other | | 0% - 10% |
|
Schedule of multiemployer plans | The Company’s participation in multiemployer plans for the years ended December 31, 2016, 2015 and 2014 is reported in the following table. The Company’s contributions to the Steelworkers Western Independent Shops Pension Plan exceed 5% of this plan’s total contributions for the plan year ended September 30, 2015, which is the most recent information available from the Plan Administrator. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pension Protection Act Zone Status (1) | | FIP / RP Status Pending / Implemented (2) | | in millions | | | | Expiration Dates of Collective Bargaining Agreements | | | EIN / Pension Plan Number | | | | Company Contributions | | Surcharge Imposed (3) | | Pension Fund | | | 2016 | | 2015 | | | 2016 | | 2015 | | 2014 | | | Steelworkers Western Independent Shops Pension Plan | | 90-0169564 / 001 | | Green | | Green | | N/A | | $ | 1.2 |
| | $ | 0.7 |
| | $ | 1.1 |
| | No | | 2/29/2020 | Boilermakers-Blacksmiths National Pension Trust | | 48-6168020 / 001 | | Yellow | | Yellow | | Yes | | 1.8 |
| | 1.8 |
| | 2.0 |
| | No | | 9/30/2018 | IAM National Pension Fund | | 51-6031295 / 002 | | Green | | Green | | N/A | | 1.6 |
| | 1.5 |
| | 1.6 |
| | No | | Various between 2018-2022 (4) | Total contributions | | | | | | | | | | $ | 4.6 |
| | $ | 4.0 |
| | $ | 4.7 |
| | | | |
| | (1) | The most recent Pension Protection Act Zone Status available for ATI’s fiscal years 2016 and 2015 is for plan years ending in calendar years 2015 and 2014, respectively. The zone status is based on information provided to ATI and other participating employers by each plan and is certified by the plan’s actuary. A plan in the “red” zone had been determined to be in “critical status”, based on criteria established by the Code, and is generally less than 65% funded. A plan in the “yellow” zone has been determined to be in “endangered status”, based on criteria established under the Code, and is generally less than 80% funded. A plan in the “green” zone has been determined to be neither in “critical status” nor in “endangered status”, and is generally at least 80% funded. |
| | (2) | The “FIP / RP Status Pending / Implemented” column indicates whether a Funding Improvement Plan, as required under the Code by plans in the “yellow” zone, or a Rehabilitation Plan, as required under the Code to be adopted by plans in the “red” zone, is pending or has been implemented as of the end of the plan year that ended in 2016. |
| | (3) | The “Surcharge Imposed” column indicates whether ATI’s contribution rate for 2016 included an amount in addition to the contribution rate specified in the applicable collective bargaining agreement, as imposed by a plan in “critical status”, in accordance with the requirements of the Code. |
| | (4) | The Company is party to five separate bargaining agreements that require contributions to this plan. Expiration dates of these collective bargaining agreements range between April 22, 2018 and March 25, 2022. |
|