CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income (loss)	$ 52,226,000	$ (79,520,000)	$ (45,375,000)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	15,640,000	14,759,000	13,807,000
Stock-based compensation expense	10,036,000	10,526,000	10,258,000
Inventory impairments and abandonments	2,903,000	148,618,000	6,949,000
Deferred and other income tax expense (benefit)	17,664,000	(37,245,000)	93,935,000
Gain on sale of fixed assets	(335,000)	(232,000)	(351,000)
Change in allowance for doubtful accounts	54,000	(74,000)	48,000
Equity in income of unconsolidated entities	(347,000)	(403,000)	(127,000)
Cash distributions of income from unconsolidated entities	306,000	408,000	331,000
Loss on extinguishment of debt, net	0	24,920,000	27,839,000
Changes in operating assets and liabilities:
Decrease (increase) in accounts receivable	6,524,000	(1,674,000)	11,875,000
Decrease in income tax receivable	315,000	0	88,000
Decrease (increase) in inventory	154,865,000	42,927,000	(95,809,000)
Decrease (increase) in other assets	3,000	323,000	(1,300,000)
Increase in trade accounts payable	1,040,000	4,720,000	17,492,000
Increase (decrease) in other liabilities	28,201,000	(14,418,000)	15,178,000
Net cash provided by operating activities	289,095,000	113,635,000	54,838,000
Cash flows from investing activities:
Capital expenditures	(10,642,000)	(21,356,000)	(17,020,000)
Proceeds from sale of fixed assets	478,000	251,000	370,000
Acquisition, net of cash acquired	0	(4,088,000)	(57,253,000)
Investments in unconsolidated entities	0	0	(421,000)
Return of capital from unconsolidated entities	0	68,000	176,000
Net cash used in investing activities	(10,164,000)	(25,125,000)	(74,148,000)
Cash flows from financing activities:
Repayment of debt	(51,150,000)	(576,548,000)	(522,465,000)
Proceeds from issuance of new debt	0	500,000,000	400,000,000
Repayment of borrowings from credit facility	(390,000,000)	(425,000,000)	(225,000,000)
Borrowings from credit facility	390,000,000	425,000,000	225,000,000
Debt issuance costs	(202,000)	(6,137,000)	(6,272,000)
Repurchase of common stock	(3,327,000)	(34,624,000)	0
Tax payments for stock-based compensation awards	(2,686,000)	(1,969,000)	(3,378,000)
Stock option exercises and other financing activities	(1,832,000)
Stock option exercises and other financing activities		314,000	64,000
Net cash used in financing activities	(59,197,000)	(118,964,000)	(132,051,000)
Increase (decrease) in cash, cash equivalents, and restricted cash	219,734,000	(30,454,000)	(151,361,000)
Cash, cash equivalents, and restricted cash at beginning of period	122,794,000	153,248,000	304,609,000
Cash, cash equivalents, and restricted cash at end of period	$ 342,528,000	$ 122,794,000	$ 153,248,000