Income Taxes - Summary of Provision for Income Taxes and Corresponding Effective Tax Rate (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income tax expense	$ 6,771	$ 3,688	$ 19,214	$ 9,807
Earnings before income tax	$ 22,658	$ 3,333	$ 46,266	$ 39,077
Effective tax rate	29.90%	110.70%	41.50%	25.10%
Income tax expense excluding impairment loss	$ 6,771	$ 3,688	$ 19,214	$ 9,807
Earnings before income tax excluding impairment loss	$ 23,495	$ 14,809	$ 67,472	$ 50,553
Effective tax rate excluding impairment loss	28.80%	24.90%	28.50%	19.40%