Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Provision for income taxes	$ (4,532)	$ (1,021)	$ (2,397)	$ (4)
Income (loss) before income taxes	8,300	3,780	2,570	7,550
Provision for income taxes before discrete items	4,457	$ 1,571	$ 1,037	$ 2,653
U.S. Statutory income tax rate			21.00%		35.00%
Tax charge					$ 27,500
Estimated charges related to deemed repatriation transition tax			$ 1,200		17,000
Estimated charges related to deemed repatriation transition tax, gross					27,000
Foreign tax credits					10,000
Estimated charges related to remeasurement of U.S. deferred tax assets and liabilities					10,500
Unrecognized tax benefits that would affect the effective tax rate if recognized	34,600		34,600		$ 33,900
Gross unrecognized tax benefits decrease in next 12 months	4,300		4,300
Offset to deferred tax assets for unrecognized tax benefits			17,100
Estimated unrecognized tax benefits	$ 17,500		$ 17,500