v3.7.0.1
Stockholders' Equity (Details) - USD ($)
shares in Millions, $ in Millions
1 Months Ended 3 Months Ended
Apr. 27, 2017
Mar. 31, 2017
Mar. 31, 2016
Feb. 28, 2017
Class of Stock [Line Items]        
Treasury Stock, Shares, Acquired   1 2  
Treasury Stock, Value, Acquired, Cost Method   $ 68 $ 297  
Subsequent Event [Member]        
Class of Stock [Line Items]        
Treasury Stock, Value, Acquired, Cost Method $ 32      
Common Stock [Member]        
Class of Stock [Line Items]        
Stock Repurchase Program, Authorized Amount       $ 1,000
Total remaining amount for repurchases under program   $ 932    
Common Stock [Member] | Subsequent Event [Member]        
Class of Stock [Line Items]        
Total remaining amount for repurchases under program $ 900