Income Taxes (Income Tax Provision (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income tax expense (benefit)
Federal	$ 2,645	$ (17,885)	$ (19,485)
State	1,236	1,884	(1,388)
Total current income tax expense (benefit)	3,881	(16,001)	(20,873)
Deferred income tax expense (benefit)
Federal	89,950	93,395	(113,863)
State	10,521	9,839	18,084
Total deferred income tax expense (benefit)	100,471	103,234	(95,779)
Total income tax expense (benefit)	$ 104,352	$ 87,233	$ (116,652)