Income Taxes - Schedule of Significant Components of Provision for Income Taxes Attributable to Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current income tax provision:
Federal taxes									$ 1,991	$ 1,934	$ 1,581
State taxes									207	197	194
International taxes									73	91	115
Total current provision									2,271	2,222	1,890
Deferred income tax (benefit) provision:
Federal taxes									(368)	(125)	284
State taxes									(39)	22	46
International taxes									5	27	4
Total deferred (benefit) provision									(402)	(76)	334
Income tax provision (benefit)	$ 426	$ 530	$ 384	$ 529	$ 450	$ 536	$ 581	$ 579	1,869	2,146	2,224
Pre-tax earnings from foreign operations									$ 288	$ 466	$ 459