Income Taxes - Additional Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, affect the effective tax rate	$ 73	$ 113	$ 96
Accrual for payment of interest and penalties associated with uncertain tax positions	28	42
Decrease in accruals for payment of interest and penalties associated with uncertain tax positions	14	46
Deferred income taxes, net	$ 2,580	$ 3,889