Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Reconciliation of Effective Income Tax Rate
Effective tax rate (as a percent)	29.50%	27.40%	28.50%	28.20%
Income tax
Net UTB impacting the effective tax rate	$ 202		$ 202		$ 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	2	1	(13)	5
Interest and penalties related to unrecognized tax benefits, accrued on a gross basis	45		45		62
Change in effective income tax rate from prior reporting period to current reporting period (as a percent)	2.10%		0.30%
Impact of factors that decreased the effective tax rate from prior reporting period to current reporting period (as a percent)			(0.80%)
Impact of factors that increased the effective tax rate from prior reporting period to current reporting period (as a percent)	2.10%		1.10%
Deferred tax assets valuation allowance	$ 28		$ 28		$ 23