Fair Value Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative related liabilities		$ (46)	$ (12)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due to affiliates carried at fair value		0	0
Derivative related liabilities		0	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due to affiliates carried at fair value		(488)	(485)
Derivative related liabilities		(46)	(12)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due to affiliates carried at fair value		0	0
Derivative related liabilities		0	0
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Netting	[1]	(21)	(15)
Netting	[1]	295	332
Recurring [Member] | Derivative netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Netting	[1]	(21)	(15)
Netting	[1]	295	332
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Total assets		0	0
Due to affiliates carried at fair value		0	0
Derivative related liabilities before netting		0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0	0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Derivative related liabilities before netting		0	0
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Derivative netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Derivative related liabilities before netting		0	0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		21	15
Total assets		21	15
Due to affiliates carried at fair value		(488)	(485)
Derivative related liabilities before netting		(341)	(344)
Financial and Nonfinancial Liabilities, Fair Value Disclosure		(2,155)	(2,146)
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		21	15
Derivative related liabilities before netting		(341)	(344)
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Derivative netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Derivative related liabilities before netting		0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Total assets		0	0
Due to affiliates carried at fair value		0	0
Derivative related liabilities before netting		0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Derivative related liabilities before netting		0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Derivative netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets before netting		0	0
Derivative related liabilities before netting		0	0
Long-term Debt Carried at Fair Value [Member] | Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long term debt carried at fair value		0	0
Long-term Debt Carried at Fair Value [Member] | Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long term debt carried at fair value		(1,326)	(1,317)
Long-term Debt Carried at Fair Value [Member] | Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long term debt carried at fair value		0	0
Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due to affiliates carried at fair value		(488)	(485)
Derivative related liabilities		(46)	(12)
Estimated Fair Value [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets		0	0
Total assets		0	0
Due to affiliates carried at fair value		(488)	(485)
Derivative related liabilities		(46)	(12)
Financial and Nonfinancial Liabilities, Fair Value Disclosure		(1,860)	(1,814)
Estimated Fair Value [Member] | Recurring [Member] | Currency swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets		21	15
Derivative related liabilities		(341)	(344)
Estimated Fair Value [Member] | Recurring [Member] | Derivative netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative financial assets		(21)	(15)
Derivative related liabilities		295	332
Estimated Fair Value [Member] | Long-term Debt Carried at Fair Value [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long term debt carried at fair value		$ (1,326)	$ (1,317)

[1] Represents counterparty and swap collateral netting which allow the offsetting of amounts relating to certain contracts when certain conditions are met.