Income Taxes - Schedule of Effective Income Tax Rate Reconciliation for Continuing Operations (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory U.S. federal income tax rate		$ 4,806	$ 12,737	$ 6,658
State taxes, net of U.S. federal benefit		1,038	1,598	395
Foreign rate differential, including withholding taxes		784	(3,849)	(805)
Charges related to U.S. Government resolutions				2,050
Valuation allowances, net		4,116	3,548	6,149
Change in estimate on compensation expenses				(2,151)
Italian subsidiary intangible asset		(230)	(381)	(1,477)
Change of intention for foreign earnings			0	1,300
Domestic manufacturing deduction			(818)
Unrecognized tax benefits, net of settlements		81	6,002	3,049
Impact of the Tax Act	$ (600)	(560)	8,347
Equity compensation		(1,646)	272	334
Contingent consideration		528
Other, net		157	1,644	25
Income tax expense		$ 9,074	$ 29,100	$ 15,527
Statutory U.S. federal income tax rate		21.00%	35.00%	35.00%
State taxes, net of U.S. federal benefit		4.50%	4.40%	2.10%
Foreign rate differential, including withholding taxes		3.40%	(10.60%)	(4.20%)
Charges related to U.S. Government resolutions				10.80%
Valuation allowances, net		18.00%	9.70%	32.30%
Change in estimate on compensation expenses				(11.30%)
Italian subsidiary intangible asset		(1.00%)	(1.00%)	(7.80%)
Change of intention for foreign earnings				6.80%
Domestic manufacturing deduction			(2.20%)
Unrecognized tax benefits, net of settlements		0.40%	16.50%	16.00%
Impact of the Tax Act		(2.40%)	22.90%
Equity compensation		(7.20%)	0.70%	1.80%
Contingent consideration		2.30%
Other, net		0.70%	4.50%	0.10%
Income tax expense/effective rate		39.70%	80.00%	81.60%