CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Loss	$ (108,958)	$ (40,560)	$ (171,185)	$ (262,897)
Other comprehensive income (loss):
Other post-retirement benefits income (loss), net of tax	0	0	3,996	0
Total other comprehensive income (loss), net of tax	0	0	3,996	0
Comprehensive income (loss)	$ (108,958)	$ (40,560)	$ (167,189)	$ (262,897)