CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Total revenue	$ 767,945	$ 511,521	$ 455,178	$ 372,489	$ 672,981	$ 478,588	$ 425,468	$ 339,241	$ 2,107,133	$ 1,916,278	$ 1,822,114
Home construction and land sales expenses									1,755,619	1,600,969	1,509,625
Inventory impairments and abandonments	6,331	168	0	0	1,693	470	282	0	6,499	2,445	15,282
Gross profit	125,865	83,244	75,077	60,829	113,360	78,443	67,398	53,663	345,015	312,864	297,207
Commissions									81,002	74,811	70,460
General and administrative expenses									168,658	161,906	153,628
Depreciation and amortization									13,807	14,009	13,794
Operating income	43,462	17,580	13,825	6,681	37,783	15,569	7,511	1,275	81,548	62,138	59,325
Equity in income of unconsolidated entities									34	371	131
Loss on extinguishment of debt	(1,935)	0	0	(25,904)	2,933	0	(15,563)	0	(27,839)	(12,630)	(13,423)
Other expense, net									(4,305)	(15,230)	(24,330)
Income from continuing operations before income taxes									49,438	34,649	21,703
Expense from income taxes									94,484	2,696	16,498
(Loss) income from continuing operations	$ 60,484	$ 13,429	$ 11,616	$ (130,575)	$ 33,693	$ 7,114	$ (7,495)	$ (1,359)	(45,046)	31,953	5,205
Loss from discontinued operations, net of tax									(329)	(140)	(512)
Net (loss) income									$ (45,375)	$ 31,813	$ 4,693
Weighted-average number of shares:
Basic (in shares)									32,141	31,952	31,798
Diluted (in shares)									32,141	32,426	31,803
Basic (loss) income per share:
Continuing operations (in dollars per share)	$ 1.88	$ 0.42	$ 0.36	$ (4.07)	$ 1.05	$ 0.22	$ (0.23)	$ (0.04)	$ (1.40)	$ 1.00	$ 0.16
Discontinued operations (in dollars per share)									(0.01)	0.00	(0.01)
Total (in dollars per share)									(1.41)	1.00	0.15
Diluted (loss) income per share:
Continuing operations (in dollars per share)	$ 1.83	$ 0.41	$ 0.36	$ (4.07)	$ 1.03	$ 0.22	$ (0.23)	$ (0.04)	(1.40)	0.99	0.16
Discontinued operations (in dollars per share)									(0.01)	0.00	(0.01)
Total (in dollars per share)									$ (1.41)	$ 0.99	$ 0.15