Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclsoure [Line Items]
Revaluation of deferred tax assets and liabilities, resulting in a net charge	$ 15,400
Foreign loss carryforwards	$ 17,900
Carryforward period	7 years
Deferred tax asset, net of valuation allowance	$ 43,706	$ 42,345
Income taxes receivable	$ 1,000	$ 2,000
U.S. statutory tax rate	21.00%	35.00%	35.00%
Carryforward limitation, 3 to 5 years
Income Tax Disclsoure [Line Items]
Operating loss carryforwards, valuation allowance	$ 600
Foreign Tax Authority | Her Majesty's Revenue and Customs (HMRC)
Income Tax Disclsoure [Line Items]
Deferred tax asset, net of valuation allowance	$ 1,900