Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (121,003)	$ (420,540)	$ (191,434)	$ (389,935)
Other comprehensive income, net of income taxes:
Minimum pension liability adjustments, net of income taxes of $(0.1) million and $(0.3) million for the three and six months ended March 31, 2021, respectively, and $(0.2) million and $(0.3) million for the three and six months ended March 31, 2020, respectively	457	516	914	1,032
Other comprehensive income	457	516	914	1,032
Comprehensive loss	$ (120,546)	$ (420,024)	$ (190,520)	$ (388,903)