v3.2.0.727
Debt Senior Unsecured Notes (Details) - Debt Instrument, Name [Domain] - USD ($)
$ in Millions
Jun. 30, 2015
Dec. 31, 2014
Debt Instrument [Line Items]    
Long-term Debt $ 11,398 $ 11,122
Senior Unsecured Notes 2023 [Member]    
Debt Instrument [Line Items]    
Long-term Debt 1,250 1,250
Senior Unsecured Notes 2024 [Member]    
Debt Instrument [Line Items]    
Long-term Debt 650 0
Senior Unsecured Notes 2025 [Member]    
Debt Instrument [Line Items]    
Long-term Debt 1,550 1,550
Unsecured Debt [Member]    
Debt Instrument [Line Items]    
Long-term Debt $ 3,450 $ 2,800