Income Taxes - Schedule of Income Tax Provision (Benefit) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 20,435,000	$ 8,461,000	$ 33,017,000
Foreign	(2,671,000)	15,246,000	28,229,000
Total current	17,764,000	23,707,000	61,246,000
Deferred:
Federal	20,592,000	1,121,000	(1,611,000)
Foreign	(3,361,000)	(2,181,000)	(1,872,000)
Total deferred	17,231,000	(1,060,000)	(3,483,000)
Total	$ 34,995,000	$ 22,647,000	$ 57,763,000