Summary of Income Tax Expense (Details) - USD ($)		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
Federal										$ 34,461,000	$ 21,510,000	$ 29,555,000
State										14,545,000	11,960,000	9,183,000
Total current income tax expense										49,006,000	33,470,000	38,738,000
Deferred
Federal	[1]									(279,000)	5,372,000	22,246,000
State	[1]									(77,000)	1,489,000	3,641,000
Total deferred income tax (benefit) expense	[1]									(356,000)	6,861,000	25,887,000
Total income tax expense		$ 12,203,000	$ 12,212,000	$ 12,568,000	$ 11,667,000	$ 11,647,000	$ 10,802,000	$ 9,485,000	$ 8,397,000	48,650,000	40,331,000	64,625,000
Tax benefit of operating loss carryforwards										$ 317,000	$ 443,000	$ 644,000

[1] Includes tax benefit of operating loss carryforwards of $317,000, $443,000 and $644,000 for the years ended December 31, 2019, 2018, and 2017, respectively.