Goodwill and Intangible Assets (Schedules for Amortization Expense) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Finite Lived Intangible Assets    
Amortization expense for acquired intangible assets $ 53 $ 57
Expected amortization expense for acquired intangible assets recorded as of balance sheet date    
Remainder of 2015 150  
2016 177  
2017 155  
2018 139  
2019 127  
2020 117  
After 2020 $ 416