Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Effective tax rate on income from continuing operations (as a percent)	24.10%	21.60%	23.00%	22.20%
Valuation allowance	$ 12		$ 12		$ 20
Gross unrecognized tax benefit (expense)	239		239		242
Unrecognized tax benefits (net of federal tax benefits) that would impact the effective tax rate	57		57		57
Increase (reduction) in interest and penalties	1	$ 1	3	$ 4
Accrued interest and penalties	52		52		$ 48
Minimum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross unrecognized tax benefits due to resolution of IRS examination	150		150
Maximum [Member]
Operating Loss Carryforwards [Line Items]
Decrease in gross unrecognized tax benefits due to resolution of IRS examination	160		160
State and Local [Member]
Operating Loss Carryforwards [Line Items]
State net operating losses	17		17
State AMT credit carryforward	$ 1		$ 1