Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0000092230 (http://www.sec.gov/CIK)

Compensation and Retirement Disclosure [Abstract]	Period [Axis]
	2016-01-01 - 2016-12-31
Compensation and Retirement Disclosure [Abstract]
Significant Actuarial Assumptions Used to Determine Net Periodic Pension Costs	The following actuarial assumptions were used to determine net periodic pension costs for the qualified pension plans:     December 31,     2016   2015   2014 Weighted average assumed discount rate   4.68 %   4.27 %   5.10 % Weighted average expected long-term rate of return on plan assets   7.00   7.50   7.75 Assumed long-term rate of annual compensation increases   4.50   4.50   5.00
Summary of the Components of Net Periodic Benefit Cost Recognized for Pension Plans	Financial data relative to qualified and nonqualified defined benefit pension plans is summarized in the following tables for the years indicated. On the Consolidated Balance Sheets, the qualified pension plan prepaid asset is recorded as a component of other assets and the nonqualified pension plans accrued liability is recorded as a component of other liabilities. The data is calculated using an actuarial measurement date of December 31.     Year Ended December 31,     2016   2015   2014     (Dollars in millions) Net Periodic Pension Cost:             Service cost   $ 186   $ 176   $ 138 Interest cost   181   157   140 Estimated return on plan assets   (326 )   (327 )   (296 ) Net amortization and other   80   67   17 Net periodic benefit cost   121   73   (1 )               Pre-Tax Amounts Recognized in OCI:             Net actuarial loss (gain)   138   230   532 Net amortization   (80 )   (67 )   (17 ) Net amount recognized in OCI   58   163   515 Total net periodic pension costs (income) recognized in total comprehensive income, pre-tax   $ 179   $ 236   $ 514
Significant Actuarial Assumptions Used to Determine Benefit Obligations	The following actuarial assumptions were used to determine benefit obligations:     December 31,     2016   2015 Weighted average assumed discount rate   4.43 %   4.68 % Assumed rate of annual compensation increases   4.50   4.50
Changes in Projected Benefit Obligation	Qualified Plans   Nonqualified Plans     Year Ended December 31,   Year Ended December 31,     2016   2015   2016   2015     (Dollars in millions) Projected benefit obligation, beginning of year   $ 3,473   $ 3,227   $ 392   $ 367 Service cost   174   164   12   12 Interest cost   163   141   18   16 Actuarial (gain) loss   152   (164 )   15   (3 ) Benefits paid   (94 )   (80 )   (11 )   (15 ) Acquisitions   71   185   —   15 Projected benefit obligation, end of year   $ 3,939   $ 3,473   $ 426   $ 392 Accumulated benefit obligation, end of year   $ 3,403   $ 2,997   $ 363   $ 309
Changes in Fair Value of Plan Assets	Qualified Plans   Nonqualified Plans     Year Ended December 31,   Year Ended December 31,     2016   2015   2016   2015     (Dollars in millions) Fair value of plan assets, beginning of year   $ 4,369   $ 4,223   $ —   $ — Actual return on plan assets   356   (70 )   —   — Employer contributions   360   126   11   15 Benefits paid   (94 )   (80 )   (11 )   (15 ) Acquisitions   53   170   —   — Fair value of plan assets, end of year   $ 5,044   $ 4,369   $ —   $ — Funded status at end of year   $ 1,105   $ 896   $ (426 )   $ (392 )
Pre-tax Amounts Recognized in AOCI	The following are the pre-tax amounts recognized in AOCI:     Qualified Plans   Nonqualified Plans     Year Ended December 31,   Year Ended December 31,     2016   2015   2016   2015     (Dollars in millions) Prior service credit (cost)   $ —   $ —   $ (1 )   $ (2 ) Net actuarial loss   (1,095 )   (1,040 )   (135 )   (131 ) Net amount recognized   $ (1,095 )   $ (1,040 )   $ (136 )   $ (133 )
Schedule of Amounts Expected to be Amortized from AOCI Into Net Periodic Pension Cost During Next Fiscal Year	The following table presents the amount expected to be amortized from AOCI into net periodic pension cost during 2017:     Qualified Plans   Nonqualified Plans     (Dollars in millions) Net actuarial loss   $ (66 )   $ (12 ) Net amount expected to be amortized in 2017   $ (66 )   $ (12 )
Schedule of Estimated Future Benefit Payments	The following table reflects the estimated benefit payments for the periods presented:     Qualified Plans   Nonqualified Plans     (Dollars in millions) 2017   $ 104   $ 15 2018   115   16 2019   125   17 2020   137   18 2021   149   20 2022-2026   949   119
Schedule of Fair Value of Pension Plan Assets by Three Level Fair Value Hierarchy	The fair values of certain pension plan assets by asset category are reflected in the following table.     December 31, 2016   December 31, 2015     Total   Level 1   Level 2   Total   Level 1   Level 2     (Dollars in millions) Cash and cash-equivalents   $ 179   $ 179   $ —   $ 266   $ 266   $ — U.S. equity securities   1,892   1,018   874   1,627   1,627   — International equity securities   839   165   674   712   614   98 Fixed income securities   1,914   10   1,904   1,631   10   1,621 Total   $ 4,824   $ 1,372   $ 3,452   $ 4,236   $ 2,517   $ 1,719