Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Income Taxes [Line Items]
Liability for uncertain tax positions	$ 1,000		$ 900
Deferred income taxes on undistributed earnings		$ (1,215)
Income tax expense	$ 842	$ 4,111
Effective income tax rate	31.10%	41.60%
U.S. federal statutory rate	21.00%
Foreign Subsidiaries [Member]
Income Taxes [Line Items]
Deferred income taxes on undistributed earnings	$ 600		$ 600
Federal Authorities [Member]
Income Taxes [Line Items]
Open tax years	2014 2015 2016 2017 2018 2019
State and Foreign Authorities [Member]
Income Taxes [Line Items]
Open tax years	2013 2014 2015 2016 2017 2018 2019