Income Taxes - Schedule of Components of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current tax expense (benefit):
Federal	$ 190,743	$ 12,054	$ (108)
State	38,499	10,927	5,120
Current tax (benefit) expense	229,242	22,981	5,012
Deferred tax (benefit) expense:
Federal	(438,281)	53,094	43,772
State	(24,904)	1,497	(97)
Deferred tax expense (benefit)	(463,185)	54,591	43,675
Income tax (benefit) expense	$ (233,943)	$ 77,572	$ 48,687