Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2024	Jun. 30, 2023	Jul. 05, 2017
Basic earnings per common share:
Net income - basic	$ 17,950	$ 18,222		$ 67,899	$ 28,210
Weighted shares outstanding - basic (in shares)	54,898,000	55,367,000		55,022,000	55,776,000
Basic earnings (loss) per common share (in dollars per share)	$ 0.33	$ 0.33		$ 1.23	$ 0.51
Diluted earnings per common share:
Net income - basic	$ 17,950	$ 18,222		$ 67,899	$ 28,210
Add: Convertible Notes expense, net of tax	2,427	2,644		7,501
Add: Convertible Notes expense, net of tax					1,885
Net income - diluted	$ 20,377	$ 20,866		$ 75,400	$ 30,095
Weighted shares outstanding - basic (in shares)	54,898,000	55,367,000		55,022,000	55,776,000
Equity-based compensation awards - effect of dilution (in shares)	1,056,000	1,041,000		1,129,000	1,058,000
Convertible Notes - effect of dilution (in shares)	27,054,000	30,417,000		28,158,000	22,725,000
Weighted shares outstanding - diluted (in shares)	83,008,000	86,825,000		84,309,000	79,559,000
Diluted earnings (loss) per common share (in dollars per share)	$ 0.25	$ 0.24		$ 0.89	$ 0.38
Potential common shares excluded from the calculation of diluted earnings (loss) per common share above (in shares)	1,917,000	1,705,000		1,913,000	8,051,000
Loss on extinguishment of debt			$ 3,500	$ 0	$ 3,545
2025 Convertible Notes
Diluted earnings per common share:
Loss on extinguishment of debt					5,400
2024 Convertible Notes | Senior Notes
Diluted earnings per common share:
Convertible Notes - effect of dilution (in shares)	75,854			25,192
Potential common shares excluded from the calculation of diluted earnings (loss) per common share above (in shares)	3,400,000
Loss on extinguishment of debt	$ 0	$ 0		$ 0	$ 8,935
Weighted average shares				1,200,000
Conversion price, per share (in dollars per share)	$ 10.00			$ 10.00		$ 10.00
Convertible Notes
Diluted earnings per common share:
Potential common shares excluded from the calculation of diluted earnings (loss) per common share above (in shares)	0	0		0	6,323,000
Restricted stock
Diluted earnings per common share:
Potential common shares excluded from the calculation of diluted earnings (loss) per common share above (in shares)	1,917,000	1,705,000		1,913,000	1,728,000