Employee Benefits (Tables)

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

Change In Benefit Obligations, Change In Plan Assets, Funded Status, Amounts Recognized on Balance Sheet, and Amounts Recognized In Accumulated Other Comprehensive Income (Pretax)

The following tables summarize benefit costs, as well as the benefit obligations, plan assets, funded status and rate assumptions associated with pension and postretirement health care and life insurance benefit plans.

Obligations and Funded Status

							(dollars in millions)
	Pension						Health Care and Life
At December 31,	2018			2017			2018			2017
Change in Benefit Obligations
Beginning of year	$	21,531		$	21,112		$	19,460		$	19,650
Service cost	284			280			127			149
Interest cost	690			683			615			659
Plan amendments	230			—			(8		)	(545		)
Actuarial (gain) loss, net	(1,418		)	1,377			(2,729		)	627
Benefits paid	(1,475		)	(1,932		)	(1,101		)	(1,080		)
Curtailment and termination benefits	181			11			—			—
Settlements paid	(456		)	—			—			—
End of year	19,567			21,531			16,364			19,460
Change in Plan Assets
Beginning of year	19,175			14,663			1,119			1,363
Actual return on plan assets	(494		)	2,342			(26		)	134
Company contributions	1,066			4,141			1,183			702
Benefits paid	(1,475		)	(1,932		)	(1,101		)	(1,080		)
Settlements paid	(456		)	—			—			—
Divestiture (Note 3)	—			(39		)	—			—
End of year	17,816			19,175			1,175			1,119
Funded Status
End of year	$	(1,751	)	$	(2,356	)	$	(15,189	)	$	(18,341	)

							(dollars in millions)
	Pension						Health Care and Life
At December 31,	2018			2017			2018			2017
Amounts recognized on the balance sheet
Noncurrent assets	$	3		$	21		$	—		$	—
Current liabilities	(71		)	(63		)	(292		)	(637		)
Noncurrent liabilities	(1,683		)	(2,314		)	(14,897		)	(17,704		)
Total	$	(1,751	)	$	(2,356	)	$	(15,189	)	$	(18,341	)
Amounts recognized in Accumulated Other Comprehensive Income (Pre-tax)
Prior service cost (benefit)	$	585		$	404		$	(4,698	)	$	(5,667	)
Total	$	585		$	404		$	(4,698	)	$	(5,667	)

Information for Pension Plans with Accumulated Benefit Obligation in Excess of Plan Assets

Information for pension plans with an accumulated benefit obligation in excess of plan assets follows:

	(dollars in millions)
At December 31,	2018		2017
Projected benefit obligation	$	19,510	$	21,300
Accumulated benefit obligation	19,461		21,242
Fair value of plan assets	17,757		18,923

Benefit or (Income) Cost Related to Pension and Postretirement Health Care and Life Insurance

The following table summarizes the components of net periodic benefit cost (income) related to our pension and postretirement health care and life insurance plans:

													(dollars in millions)
	Pension									Health Care and Life
Years Ended December 31,	2018			2017			2016			2018			2017			2016
Service cost - Cost of services	$	230		$	215		$	252		$	104		$	116		$	150
Service cost - Selling, general and administrative expense	54			65			70			23			33			43
Service cost	284			280			322			127			149			193
Amortization of prior service cost (credit)	48			39			21			(976		)	(949		)	(657		)
Expected return on plan assets	(1,293		)	(1,262		)	(1,045		)	(44		)	(53		)	(54		)
Interest cost	690			683			677			615			659			746
Remeasurement loss (gain), net	369			337			1,198			(2,658		)	546			1,300
Curtailment and termination benefits	181			11			4			—			—			—
Other components	(5		)	(192		)	855			(3,063		)	203			1,335
Total	$	279		$	88		$	1,177		$	(2,936	)	$	352		$	1,528

Other Pretax Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss

Other pre-tax changes in plan assets and benefit obligations recognized in other comprehensive (income) loss are as follows:

										(dollars in millions)
	Pension									Health Care and Life
At December 31,	2018			2017			2016			2018			2017			2016
Prior service cost (benefit)	$	230		$	—		$	428		$	(8	)	$	(544	)	$	(5,142	)
Reversal of amortization items
Prior service (benefit) cost	(48		)	(39		)	(21		)	976			949			657
Amounts reclassified to net income	—			—			87			—			—			451
Total recognized in other comprehensive loss (income) (pre-tax)	$	182		$	(39	)	$	494		$	968		$	405		$	(4,034	)

Weighted Average Assumptions Used in Determining Benefit Obligations and Net Periodic Cost

The weighted-average assumptions used in determining benefit obligations follow:

	Pension				Health Care and Life
At December 31,	2018		2017		2018		2017
Discount Rate	4.40	%	3.70	%	4.30	%	3.60	%
Rate of compensation increases	3.00		3.00		N/A		N/A

The weighted-average assumptions used in determining net periodic cost follow:

	Pension						Health Care and Life
At December 31,	2018		2017		2016		2018		2017		2016
Discount rate in effect for determining service cost	4.10	%	4.70	%	4.50	%	3.90	%	4.60	%	4.20	%
Discount rate in effect for determining interest cost	3.40		3.40		3.20		3.20		3.50		4.20
Expected return on plan assets	7.00		7.70		7.00		4.80		4.50		4.80
Rate of compensation increases	3.00		3.00		3.00		N/A		N/A		N/A

Health Care Cost Trend Rates

The assumed health care cost trend rates follow:

	Health Care and Life
At December 31,	2018		2017		2016
Healthcare cost trend rate assumed for next year	6.30	%	7.00	%	6.50	%
Rate to which cost trend rate gradually declines	4.50		4.50		4.50
Year the rate reaches the level it is assumed to remain thereafter	2027		2026		2025

Effects of One Percentage Point Change in Assumed Health Care Cost Trend Rates

A one-percentage point change in the assumed health care cost trend rate would have the following effects:

	(dollars in millions)
One-Percentage Point	Increase		Decrease
Effect on 2018 service and interest cost	$	20	$	(19	)
Effect on postretirement benefit obligation as of December 31, 2018	462		(485		)

Fair Values for Plans by Asset Category

The fair values for the pension plans by asset category at December 31, 2018 are as follows:

	(dollars in millions)
Asset Category	Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	1,701	$	1,694	$	7	$	—
Equity securities	2,253		2,220		20		13
Fixed income securities
U.S. Treasuries and agencies	1,684		1,557		127		—
Corporate bonds	3,645		124		3,244		277
International bonds	1,113		19		1,076		18
Other	—		—		—		—
Real estate	727		—		—		727
Other
Private equity	664		—		—		664
Hedge funds	459		—		373		86
Total investments at fair value	12,246		5,614		4,847		1,785
Investments measured at NAV	5,570
Total	$	17,816	$	5,614	$	4,847	$	1,785

The fair values for the pension plans by asset category at December 31, 2017 are as follows:

	(dollars in millions)
Asset Category	Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	2,889	$	2,874	$	15	$	—
Equity securities	2,795		2,794		—		1
Fixed income securities
U.S. Treasuries and agencies	1,382		1,234		148		—
Corporate bonds	2,961		139		2,718		104
International bonds	1,068		17		1,031		20
Other	396		4		392		—
Real estate	627		—		—		627
Other
Private equity	580		—		—		580
Hedge funds	845		—		660		185
Total investments at fair value	13,543		7,062		4,964		1,517
Investments measured at NAV	5,632
Total	$	19,175	$	7,062	$	4,964	$	1,517

Health Care and Life Plans

The fair values for the other postretirement benefit plans by asset category at December 31, 2018 are as follows:

	(dollars in millions)
Asset Category	Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	471	$	431	$	40	$	—
Equity securities	239		239		—		—
Fixed income securities
U.S. Treasuries and agencies	24		24		—		—
Corporate bonds	96		96		—		—
International bonds	18		18		—		—
Total investments at fair value	848		808		40		—
Investments measured at NAV	327
Total	$	1,175	$	808	$	40	$	—

The fair values for the other postretirement benefit plans by asset category at December 31, 2017 are as follows:

	(dollars in millions)
Asset Category	Total		Level 1		Level 2		Level 3
Cash and cash equivalents	$	71	$	1	$	70	$	—
Equity securities	294		294		—		—
Fixed income securities
U.S. Treasuries and agencies	23		22		1		—
Corporate bonds	141		141		—		—
International bonds	60		18		42		—
Total investments at fair value	589		476		113		—
Investments measured at NAV	530
Total	$	1,119	$	476	$	113	$	—

Reconciliation of Beginning and Ending Balance of Plan Assets Measured at Fair Value

The following is a reconciliation of the beginning and ending balance of pension plan assets that are measured at fair value using significant unobservable inputs:

	(dollars in millions)
	Equity Securities			Corporate Bonds			International Bonds			Real Estate			Private Equity			Hedge Funds			Total
Balance at January 1, 2017	$	—		$	97		$	14		$	655		$	624		$	4		$	1,394
Actual gain (loss) on plan assets	—			(1		)	—			76			78			—			153
Purchases (sales)	119			27			22			(70		)	(114		)	183			167
Transfers out	(118		)	(19		)	(16		)	(34		)	(8		)	(2		)	(197		)
Balance at December 31, 2017	1			104			20			627			580			185			1,517
Actual gain (loss) on plan assets	1			(7		)	3			134			25			—			156
Purchases (sales)	11			177			(5		)	(34		)	59			62			270
Transfers out	—			3			—			—			—			(161		)	(158		)
Balance at December 31, 2018	$	13		$	277		$	18		$	727		$	664		$	86		$	1,785

Expected Benefit Payments to Retirees

The benefit payments to retirees are expected to be paid as follows:

			(dollars in millions)
Year	Pension Benefits		Health Care and Life
2019	$	2,771	$	1,086
2020	1,796		1,113
2021	1,578		1,130
2022	1,526		1,135
2023	1,500		1,137
2024 to 2028	5,008		5,689

Schedule of Recorded Severance Liability

The following table provides an analysis of our severance liability recorded in accordance with the accounting standard regarding employers’ accounting for postemployment benefits:

								(dollars in millions)
Year	Beginning of Year		Charged to Expense		Payments			Other			End of Year
2016	$	800	$	417	$	(583	)	$	22		$	656
2017	656		581		(564		)	(46		)	627
2018	627		2,093		(560		)	(4		)	2,156