Unaudited Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance (in shares) at Sep. 30, 2020			112,151					4,663
Beginning balance at Sep. 30, 2020	$ 3,318,514	$ (1,251)	$ 11,215	$ 521,628	$ 3,010,012	$ (1,251)	$ (26,188)	$ (198,153)
Increase (Decrease) in Shareholders' Equity
Net loss	(70,431)				(70,431)
Other comprehensive income	457						457
Dividends declared	(27,324)				(27,324)
Vesting of restricted stock awards, net of shares withheld for employee taxes (in shares)			72					(295)
Vesting of restricted stock awards, net of shares withheld for employee taxes	(2,117)		$ 7	(16,742)				$ 14,618
Stock-based compensation	7,451			7,451
Other	(381)			(381)
Balance (in shares) at Dec. 31, 2020			112,223					4,368
Ending balance at Dec. 31, 2020	3,224,918		$ 11,222	511,956	2,911,006		(25,731)	$ (183,535)
Balance (in shares) at Sep. 30, 2020			112,151					4,663
Beginning balance at Sep. 30, 2020	3,318,514	$ (1,251)	$ 11,215	521,628	3,010,012	$ (1,251)	(26,188)	$ (198,153)
Increase (Decrease) in Shareholders' Equity
Net loss	(191,434)
Other comprehensive income	914
Balance (in shares) at Mar. 31, 2021			112,223					4,329
Ending balance at Mar. 31, 2021	3,083,696		$ 11,222	516,870	2,762,735		(25,274)	$ (181,857)
Balance (in shares) at Dec. 31, 2020			112,223					4,368
Beginning balance at Dec. 31, 2020	3,224,918		$ 11,222	511,956	2,911,006		(25,731)	$ (183,535)
Increase (Decrease) in Shareholders' Equity
Net loss	(121,003)				(121,003)
Other comprehensive income	457						457
Dividends declared	(27,268)				(27,268)
Vesting of restricted stock awards, net of shares withheld for employee taxes (in shares)								(39)
Vesting of restricted stock awards, net of shares withheld for employee taxes	0			(1,678)				$ 1,678
Stock-based compensation	6,826			6,826
Other	(234)			(234)
Balance (in shares) at Mar. 31, 2021			112,223					4,329
Ending balance at Mar. 31, 2021	3,083,696		$ 11,222	516,870	2,762,735		(25,274)	$ (181,857)
Balance (in shares) at Sep. 30, 2021			112,222					4,324
Beginning balance at Sep. 30, 2021	2,912,618		$ 11,222	529,903	2,573,375		(20,244)	$ (181,638)
Increase (Decrease) in Shareholders' Equity
Net loss	(51,362)				(51,362)
Other comprehensive income	394						394
Dividends declared	(26,807)				(26,807)
Vesting of restricted stock awards, net of shares withheld for employee taxes (in shares)								(381)
Vesting of restricted stock awards, net of shares withheld for employee taxes	(4,112)			(21,152)				$ 17,040
Stock-based compensation	6,218			6,218
Share repurchases (in shares)								2,548
Share repurchases	(60,358)							$ (60,358)
Balance (in shares) at Dec. 31, 2021			112,222					6,491
Ending balance at Dec. 31, 2021	2,776,591		$ 11,222	514,969	2,495,206		(19,850)	$ (224,956)
Balance (in shares) at Sep. 30, 2021			112,222					4,324
Beginning balance at Sep. 30, 2021	2,912,618		$ 11,222	529,903	2,573,375		(20,244)	$ (181,638)
Increase (Decrease) in Shareholders' Equity
Net loss	(56,338)
Other comprehensive income	788
Balance (in shares) at Mar. 31, 2022			112,222					6,937
Ending balance at Mar. 31, 2022	2,734,410		$ 11,222	514,771	2,463,665		(19,456)	$ (235,792)
Balance (in shares) at Dec. 31, 2021			112,222					6,491
Beginning balance at Dec. 31, 2021	2,776,591		$ 11,222	514,969	2,495,206		(19,850)	$ (224,956)
Increase (Decrease) in Shareholders' Equity
Net loss	(4,976)				(4,976)
Other comprehensive income	394						394
Dividends declared	(26,565)				(26,565)
Vesting of restricted stock awards, net of shares withheld for employee taxes (in shares)								(161)
Vesting of restricted stock awards, net of shares withheld for employee taxes	(1,392)			(7,197)				$ 5,805
Stock-based compensation	6,999			6,999
Share repurchases (in shares)								607
Share repurchases	(16,641)							$ (16,641)
Balance (in shares) at Mar. 31, 2022			112,222					6,937
Ending balance at Mar. 31, 2022	$ 2,734,410		$ 11,222	$ 514,771	$ 2,463,665		$ (19,456)	$ (235,792)