Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Liability for unrecognized tax	$ 5,800		$ 5,400
Accrued interest and penalties applied to uncertain tax positions	2,200		$ 2,100
Income tax expense (benefit)	$ 1,604	$ 2,342