Income Taxes Level 4 (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Valuation Allowance [Line Items]        
Deferred Tax Assets, Valuation Allowance $ 588 $ 518 $ 122 $ 432
Income tax benefit $ (26) $ (349) $ 384