v3.10.0.1
Debt - Schedule of Long-Term Debt (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Range of interest rates 0.00%  
Average rate of interest 4.00%  
Principal amount outstanding $ 7,427 $ 6,679
Due in 2019 1,152  
Due after 2019 6,275  
Due after 2023 $ 2,019  
Average remaining term (in years) 3 years 9 months 18 days  
Revolving Credit Facility [Member]    
Debt Instrument [Line Items]    
Range of interest rates [1] 0.00%  
Average rate of interest [1] 0.00%  
Principal amount outstanding [1] $ 0 0
Due in 2019 [1] 0  
Due after 2019 [1] 0  
Due after 2023 [1] $ 0  
Notes Payable to Banks [Member] | USD Notes [Member]    
Debt Instrument [Line Items]    
Average rate of interest 4.50%  
Principal amount outstanding $ 6,250 5,500
Due in 2019 0  
Due after 2019 6,250  
Due after 2023 $ 2,000  
Average remaining term (in years) 4 years 3 months 18 days  
Notes Payable to Banks [Member] | USD Notes [Member] | Minimum [Member]    
Debt Instrument [Line Items]    
Range of interest rates 3.90%  
Notes Payable to Banks [Member] | USD Notes [Member] | Maximum [Member]    
Debt Instrument [Line Items]    
Range of interest rates 5.80%  
Convertible Debt [Member] | 2019 Cash Convertible Senior Notes [Member]    
Debt Instrument [Line Items]    
Range of interest rates 1.00%  
Average rate of interest 1.00%  
Principal amount outstanding $ 1,150 1,150
Due in 2019 1,150  
Due after 2019 0  
Due after 2023 $ 0  
Average remaining term (in years) 10 months 24 days  
Bank Borrowings [Member]    
Debt Instrument [Line Items]    
Range of interest rates 0.00%  
Average rate of interest 0.00%  
Principal amount outstanding $ 0 0
Due in 2019 0  
Due after 2019 0  
Due after 2023 $ 0  
Capital Lease [Member]    
Debt Instrument [Line Items]    
Average rate of interest 4.60%  
Principal amount outstanding $ 27 $ 29
Due in 2019 2  
Due after 2019 25  
Due after 2023 $ 19  
Average remaining term (in years) 13 years 2 months 12 days  
Capital Lease [Member] | Minimum [Member]    
Debt Instrument [Line Items]    
Range of interest rates 4.50%  
Capital Lease [Member] | Maximum [Member]    
Debt Instrument [Line Items]    
Range of interest rates 13.80%  
[1] We do not have any borrowings under the $600 million Revolving Credit Facility as of December 31, 2018 and 2017.