Segment Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Sep. 30, 2021 USD ($) segment state region	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of states with active operations | state		13
Number of regions in which entity operates | region		3
Number of homebuilding segments | segment		3
Segment Reporting Information [Line Items]
Total revenue		$ 2,140,303	$ 2,127,077	$ 2,087,739
Total operating income (loss)		146,869	79,107	(89,896)
Inventory Impairment, Results of Discounted Cash Flow Analysis	$ 109,000	900	1,700	131,700
Write Off Capitalized Interest and Capitalized Indirect Cost		0	1,200	16,900
Depreciation and amortization		13,976	15,640	14,759
Capital expenditures		14,645	10,642	21,356
Assets		2,078,810	2,007,480
Operating Segments
Segment Reporting Information [Line Items]
Total operating income (loss)		323,514	258,851	86,249
Depreciation and amortization		12,009	13,542	13,161
Corporate and unallocated
Segment Reporting Information [Line Items]
Total operating income (loss)		(176,645)	(179,744)	(176,145)
Depreciation and amortization		1,967	2,098	1,598
Capital expenditures		4,725	357	4,117
Assets		676,779	779,694
West
Segment Reporting Information [Line Items]
Total revenue		1,118,578	1,183,339	1,014,702
West | Operating Segments
Segment Reporting Information [Line Items]
Total operating income (loss)		181,303	161,786	(5,492)
Depreciation and amortization		7,250	8,227	6,456
Capital expenditures		6,924	5,063	11,635
Assets		819,317	658,909
East
Segment Reporting Information [Line Items]
Total revenue		569,835	477,624	514,961
East | Operating Segments
Segment Reporting Information [Line Items]
Total operating income (loss)		84,630	56,319	51,576
Depreciation and amortization		2,207	2,458	3,250
Capital expenditures		1,549	2,237	2,518
Assets		286,133	267,050
Southeast
Segment Reporting Information [Line Items]
Total revenue		451,890	466,114	558,076
Southeast | Operating Segments
Segment Reporting Information [Line Items]
Total operating income (loss)		57,581	40,746	40,165
Depreciation and amortization		2,552	2,857	3,455
Capital expenditures		1,447	2,985	$ 3,086
Assets		$ 296,581	$ 301,827