Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
Federal	$ 187,741	$ 112,517	$ 75,582
State	9,421	2,085	7,081
Total current income tax expense	197,162	114,602	82,663
Deferred
Federal	(90,777)	46,182	24,894
State	4,585	40,451	11,321
Total deferred income tax (benefit) expense	(86,192)	86,633	36,215
Total income tax expense	$ 110,970	$ 201,235	$ 118,878