Income Taxes - Components of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal		$ 13,961	$ 3,325	$ 572
State		1,113	680	(863)
Foreign		1,172	1,832	423
Total current		16,246	5,837	132
Deferred:
Federal		(7,176)	27,179	45,077
State		(10)	4,408	1,491
Foreign		(2,528)	(215)	(17,921)
Total deferred provision	$ 20,200	(9,714)	31,372	28,647
Provision for income taxes		$ 6,532	$ 37,209	$ 28,779