Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 14,505	$ 1,361	$ 29,504	$ 2,107
Deferred income tax expense (benefit)	369	12,475	(675)	22,886
Income tax expense, as reported	$ 14,874	$ 13,836	$ 28,829	$ 24,993
Effective tax rate	11.80%	11.10%	11.20%	10.30%