Income Taxes - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Income tax expense (benefit) related to revaluation of deferred tax liability																	$ 4,500
Undistributed accumulated earnings of foreign subsidiary	$ 12,000																12,000
Income tax expense (benefit) from repatriation tax																	500
Undistributed accumulated earnings of foreign subsidiary previously marked for reinvestment	6,200																6,200
Income tax expense (benefit) related to revaluation of deferred tax asset																	300
Income tax expense (benefit) related to Tax Reform Act																	$ 3,700
Effective tax rate for income from continuing operations (as percent)																	19.50%	32.40%	34.90%
Income tax expense (benefit) for change in tax rate																	$ 1,700
Income tax expense																	11,974	$ 17,821	$ 24,764
Income tax expense (benefit) from domestic production activities deduction																	1,100
Income tax expense (benefit) from stock-based compensation																	2,700
Income tax expense (benefit) from release of reserves																	1,500
Net income/(loss)	13,848	$ 10,675	$ 13,125	$ 11,669	$ 4,420	$ 12,785	$ 10,813	$ 9,169									49,317	37,187	46,259
Effective income tax rate reconciliation, tax expense (benefit) foreign income tax rate differential																		1,300	1,000
Effective income tax rate reconciliation, tax benefit attributable to the Domestic Production Activities Deduction																		1,500	1,200
Effective income tax rate reconciliation, tax credit related to research and development credits																		1,100	1,100
Increase in valuation allowance against certain deferred tax assets																		(1,200)	(900)
Reasonably expected net unrecognized benefits may be recognized	200																200
Total amount of net unrecognized tax benefits that would affect the effective tax rate if recognized	2,500																2,500
Amount of unrecognized tax benefit, if recognized, would be offset	1,500																1,500
Netherlands and China
Income Taxes [Line Items]
Increase in valuation allowance against certain deferred tax assets																		500	800
China
Income Taxes [Line Items]
Change in valuation allowance																	300
State
Income Taxes [Line Items]
Effective income tax rate reconciliation, state and local income taxes																		$ 700	$ 600
Operating loss carryforward	4,000																4,000
State tax credit carry forwards that expire between 2017 and 2032	2,200																2,200
Valuation reserve	2,200																2,200
Foreign | China
Income Taxes [Line Items]
Operating loss carryforward	6,000																6,000
Foreign | Germany
Income Taxes [Line Items]
Operating loss carryforward	5,200																5,200
Foreign | Netherlands
Income Taxes [Line Items]
Operating loss carryforward	10,000																10,000
Restatement Adjustment
Income Taxes [Line Items]
Net income/(loss)	$ (800)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)	$ (100)
Foreign Tax Error | Restatement Adjustment
Income Taxes [Line Items]
Income tax expense																	$ 700