Fair Value Measurements - Change in Redeemable Noncontrolling Interests (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Redeemable Noncontrolling Interests [Roll Forward]
Balance, beginning of period	$ 151,978	$ 45,755	$ 38,624
Addition to redeemable noncontrolling interest		277	826
Redemption of redeemable noncontrolling interest	(138,835)		(3,562)
Deconsolidation upon sale of redeemable noncontrolling interest	5,535
Net loss attributable to redeemable noncontrolling interest	(4,791)	(4,905)	(47,831)
Adjustment of the redeemable noncontrolling interest to fair value	(7,419)	108,296	74,194
Effect of foreign currency translation attributable to redeemable noncontrolling interest	(6,468)	2,555	(16,496)
Balance, end of period	$ 0	$ 151,978	$ 45,755