Summary of Goodwill (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2020	Sep. 30, 2020
Goodwill [Line Items]
Beginning Balance	[1]		$ 1,283,371
Impairment	[2]		(16,128)
Foreign currency translation adjustments			(17,816)
Ending Balance		$ 1,249,427	1,249,427
U.S. Operating Segment
Goodwill [Line Items]
Beginning Balance	[1]		1,182,853
Ending Balance		1,182,853	1,182,853
International Operating Segment
Goodwill [Line Items]
Beginning Balance	[1]		100,518
Impairment		(16,128)	(16,128)	[2]
Foreign currency translation adjustments			(17,816)
Ending Balance		$ 66,574	$ 66,574

[1] Balances are presented net of accumulated impairment losses of $214,031 for the U.S. operating segment and $27,622 for the international operating segment.

[2] See Note 13 for discussion of impairment evaluations performed during the nine months ended September 30, 2020.