Accumulated Other Comprehensive Income (Loss) - Components of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss) before reclassifications	$ (23)	$ (4)	$ (16)
Amounts reclassified from AOCI	16	9	(29)
Tax benefit (expense)	0	(2)	6
Other comprehensive income (loss)	(7)	3	(39)
Unrealized (loss) gain on sales hedging
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	6	(1)	5
Other comprehensive income (loss) before reclassifications	(26)	1	7
Amounts reclassified from AOCI	8	7	(15)
Tax benefit (expense)	3	(1)	2
Other comprehensive income (loss)	(15)	7	(6)
Ending balance	(9)	6	(1)
Unrealized (loss) gain on forward interest rate swaps
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(15)	(15)	(8)
Other comprehensive income (loss) before reclassifications	1	(1)	(12)
Amounts reclassified from AOCI	8	2	1
Tax benefit (expense)	(3)	(1)	4
Other comprehensive income (loss)	6	0	(7)
Ending balance	(9)	(15)	(15)
Currency translation adjustments
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(36)	(32)	(6)
Other comprehensive income (loss) before reclassifications	2	(4)	(11)
Amounts reclassified from AOCI	0	0	(15)
Tax benefit (expense)	0	0	0
Other comprehensive income (loss)	2	(4)	(26)
Ending balance	(34)	(36)	(32)
Total
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(45)	(48)	(9)
Ending balance	$ (52)	$ (45)	$ (48)