Income Taxes - Summary of Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
U.S. federal	$ 1,650	$ 17,637	$ 12,127
State	1,732	1,761	1,988
Total current income tax provision	3,382	19,398	14,115
Deferred:
U.S. federal	27,114	(21,221)	12,599
State	356	445	181
Total deferred income tax provision	27,470	(20,776)	12,780
Total income tax provision	$ 30,852	$ (1,378)	$ 26,895