Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (70,431)	$ 30,605
Other comprehensive income, net of income taxes:
Amortization of actuarial losses, net of income taxes of $(0.1) million and $(0.2) million, respectively	457	516
Other comprehensive income	457	516
Comprehensive income (loss)	$ (69,974)	$ 31,121