Income Taxes (Schedule of Earnings Before Income Taxes and Provision for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States	$ 9,441	$ 9,809	$ 21,867
Outside United States	(100)	19	(15)
Earnings before income taxes	9,341	9,828	21,852
Current:
Federal	1,911	2,346	4,093
State and local	519	366	390
Outside United States	1	15	6
Total current provision for income taxes	2,431	2,727	4,489
Deferred:
Federal	(18)	(3,213)	3,102
State and local	(42)	86	20
Outside United States	3	1	(3)
Total deferred provision for income taxes	(57)	(3,126)	3,119
Total provision (benefit) for income taxes	$ 2,374	$ (399)	$ 7,608