CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (in thousands) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 508,407	$ (160,843)	$ (757,744)
Other comprehensive income (loss), net of tax:
Pension liability adjustment	[1]	4,378	767	(1,154)
Other comprehensive income (loss), net of tax		4,378	767	(1,154)
Total comprehensive income (loss)		$ 512,785	$ (160,076)	$ (758,898)

[1] (1) Please refer to Note 8 – Pension Benefits for additional discussion on the pension liability adjustment.