Income Taxes - Summary of Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current expense:
Federal									$ 95,317	$ 51,147	$ 8,483
State									36,457	28,898	5,500
Total current expense									131,774	80,045	13,983
Deferred expense (benefit):
Federal									10,444	(17,463)	49,169
State									4,784	5,683	27,679
Total deferred expense									15,228	(11,780)	76,848
Income tax expense	$ 36,967	$ 25,307	$ 27,532	$ 57,196	$ 18,074	$ 18,046	$ 18,961	$ 13,184	$ 147,002	$ 68,265	$ 90,831