Income Taxes (Schedule of Earnings Before Income Taxes and Provision for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
United States	$ 8,078	$ 7,763	$ 6,929
Outside United States	0	11	13
Earnings before income taxes	8,078	7,774	6,942
Current:
Federal - Current	2,516	2,350	2,066
State and local - Current	451	480	423
Outside United States - Current	0	3	4
Total current provision for income taxes	2,967	2,833	2,493
Deferred:
Federal - Deferred	(140)	(124)	(77)
State and local - Deferred	8	(5)	(9)
Total deferred provision for income taxes	(132)	(129)	(86)
Total provision for income taxes	$ 2,835	$ 2,704	$ 2,407