Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Disclosure [Line Items]
Income tax expense (benefit)	$ 32	$ 29	$ 34	$ 33
Pension Plan, Defined Benefit [Member]
Income Tax Disclosure [Line Items]
Settlement	$ 427	$ 0	$ 427	$ (2)