v3.7.0.1
Debt (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2015
Jun. 22, 2015
Debt Instrument [Line Items]        
Repayments of Debt $ 44      
Amortization of Financing Costs 2 $ 3    
Credit Agreement [Member]        
Debt Instrument [Line Items]        
Payments of Financing Costs     $ 45  
Senior Secured Term Loan [Member] | Credit Agreement [Member]        
Debt Instrument [Line Items]        
Debt instrument, principal amount       $ 3,500
Debt Instrument, Quarterly Payment, Percentage of Total Borrowings       1.25%
Outstanding debt 3,037      
Line of Credit [Member] | Credit Agreement [Member]        
Debt Instrument [Line Items]        
Line of credit facility, maximum borrowing capacity       $ 500
Letters of credit, amount outstanding 16      
Line of credit facility, borrowing availability $ 484      
Letter of Credit [Member] | Credit Agreement [Member]        
Debt Instrument [Line Items]        
Sublimit for letter of credit for working capital requirements and other general corporate purposes       100
Bridge Loan [Member] | Credit Agreement [Member]        
Debt Instrument [Line Items]        
Sublimit for letter of credit for working capital requirements and other general corporate purposes       $ 25