Income Taxes Components of Provision for Income Taxes, Net (Details) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2015	[1]	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2015	[1]	Dec. 31, 2014	[1]	Sep. 30, 2014	[1]	Jun. 30, 2014	[1]	Mar. 31, 2014	[1]	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current taxes:
U.S. Federal																	$ 215	$ 214	$ 99
U.S. State																	237	65	45
International																	417	204	173
Current taxes																	869	483	317
Deferred taxes:
U.S. Federal																	473	(125)	(114)
U.S. State																	(171)	(11)	(19)
International																	(221)	(180)	(23)
Deferred taxes																	81	(316)	(156)
Provision for income taxes, net	$ 453		$ 161		$ 266		$ 71		$ 205		$ (205)		$ 94		$ 73		$ 950	$ 167	$ 161

[1] The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is due to the effects of rounding and changes in the number of weighted-average shares outstanding for each period.