Debt - Extinguishment of Debt (Detail) $ in Millions	Dec. 31, 2016 USD ($)
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	$ 1,689
Notes1.450% due May 15, 2017
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	226
Notes 1.800% due December 15, 2017
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	250
Notes Due 2019
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	153
Notes 6.375% Due August 1, 2019
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	338
Notes 2.675% due December 15, 2019
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	125
Notes 3.875% due May 15, 2024
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	221
Notes 3.734% Due December 15, 2024
Extinguishment of Debt [Line Items]
Debt Instrument, Repurchased Face Amount	$ 375