CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) (in thousands) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 50,388	$ 17,197	$ (127,180)	$ 334,598
Other comprehensive income, net of tax:
Pension liability adjustment	119	198	382	458
Total other comprehensive income, net of tax	119	198	382	458
Total comprehensive income (loss)	$ 50,507	$ 17,395	$ (126,798)	$ 335,056