Income Taxes - Income Tax Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current taxes
U.S. income	$ 382	$ 604	$ 320
Foreign income	77	72	58
State income	42	43	20
Total taxes, current	501	719	398
Deferred taxes (benefits)
U.S. Income	152	131	193
Foreign income	46	4	23
State income	(1)	(1)	1
Total taxes, deferred	197	134	217
Total taxes	$ 698	$ 853	$ 615