Income Taxes (Details) (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
Income Taxes
Effective tax rate on income from continuing operations (as a percent)	24.50%	29.60%	22.50%	27.10%
Benefits Tax Planning and Completion of Audits	$ 17
Valuation allowance	19		19		19
Gross unrecognized tax benefit (expense)	230		230		209
Unrecognized tax benefits (net of federal tax benefits) that would impact the effective tax rate	45		45		62
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	170		170
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound	180		180
Increase (reduction) in interest and penalties	4	1	3	2
Accrued interest and penalties	45		45		42
State and Local
Income Taxes
State net operating losses	$ 23		$ 23