Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Reconciliation of Effective Income Tax Rate
Effective tax rate (as a percent)	30.30%	27.40%	29.10%	28.00%
Income tax
Net UTB impacting the effective tax rate	$ 238		$ 238		$ 262
Period discussed over which the Company is not able to reasonably estimate the amount by which the liability for unrecognized tax benefits could change as a result of ongoing income tax authority examinations			12 months
Interest and penalties related to unrecognized tax benefits, expense (benefit) recognized on a gross basis	(1)	7	(14)	12
Interest and penalties related to unrecognized tax benefits, accrued on a gross basis	43		43		62
Change in effective income tax rate from prior reporting period to current reporting period (as a percent)	2.90%		1.10%
Impact of factors that decreased the effective tax rate from prior reporting period to current reporting period (as a percent)	(0.40%)		(0.60%)
Impact of factors that increased the effective tax rate from prior reporting period to current reporting period (as a percent)	3.30%		1.70%
Deferred tax assets valuation allowance	$ 30		$ 30		$ 23