Income Taxes Computed at Federal Statutory Rate (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income from continuing operations before taxes	$ (26,171)	$ (33,196)	$ 86,294	$ 19,002	$ (71,227)	$ (14,353)	$ 114,279	$ 20,327	$ 45,929	$ 49,026	$ 121,412
Provision for income taxes:
Tax at Federal statutory rate									9,645	10,295	25,496
State taxes net of federal benefit									3,401	3,251	7,927
Permanent differences									520	249	196
Change in valuation allowance									252	208	86
Other									166	(265)	(30)
Income tax expense									$ 13,984	$ 13,738	$ 33,675