CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) (in thousands) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (177,568)	$ 317,401
Other comprehensive income, net of tax:
Pension liability adjustment	263	260
Total other comprehensive income, net of tax	263	260
Total comprehensive income (loss)	$ (177,305)	$ 317,661