Income Taxes - Provision for Income Taxes (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Federal:
Current	$ 698	$ 792	$ 488
Deferred	(163)	(80)	14
Federal, total	535	712	502
State:
Current	84	74	70
Deferred	(23)	(12)	(45)
State, total	61	62	25
Foreign:
Current	192	169	101
Deferred	(16)	(25)	12
Foreign, total	176	144	113
Total provision for income taxes	$ 772	$ 918	$ 640