Basis of Presentation (Unaudited) (Details 4) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017	Jan. 01, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Pro Forma Adjustments, Additional depreciation expense, net of removal of historical depreciation	$ (7)	$ (8)	$ (7)	$ (10)
Unamortized benefit plan costs, net of tax benefit of $1,940 for 2018 and $3,056 for 2017	5,474		5,474			$ 4,586
Accumulated Other Comprehensive Loss
Cumulative translation adjustment	(138)		(138)			(136)
Other, net	(4)		(4)			4
Total accumulated other comprehensive loss	(5,616)		(5,616)			(4,718)
Unamortized benefit plan costs - Tax Benefit (expense)	1,940		1,940			3,056
Unamortized benefit plan costs, net actuarial losses, after-tax	5,600		5,600			4,700
Unamortized benefit plan costs, reclassified from other comprehensive income to net earnings	$ 86	$ 100	$ 172	$ 199
Restatement Adjustment [Member] | Accounting Standards Update 2018-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect Of New Accounting Principle In Period Of Adoption					$ 1,100
Tax Cuts and Job Act, Income Tax Expense (Benefit)					73
Restatement Adjustment [Member] | Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect Of New Accounting Principle In Period Of Adoption					$ 4
Restatement Adjustment [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect Of New Accounting Principle In Period Of Adoption							$ 148
Accumulated Other Comprehensive Loss
Total accumulated other comprehensive loss						$ 0