Income Taxes (Schedule of Unresolved Income Tax Positions) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Balance at beginning of year	$ 227	$ 249
Increases related to current year income tax positions	22	17
Increases related to prior year income tax positions	56	3
Settlements and resolutions of income tax audits	(37)	(19)
Statute of limitations expirations	(64)	(23)
Balance at end of year	204	227
Current liabilities—Income taxes	10	11
Noncurrent liabilities—Other liabilities	$ 194	$ 216