Segment Information (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020 USD ($) region state	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2020 USD ($) region state segment	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Segment Reporting [Abstract]
Number of states with active operations | state	13								13
Number of regions in which entity operates | region	3								3
Number of homebuilding segments | segment									3
Segment Reporting Information [Line Items]
Total revenue									$ 2,127,077	$ 2,087,739	$ 2,107,133
Operating (loss) income	$ 35,586	$ 23,151	$ 16,424	$ 3,946	$ 36,005	$ 9,543	$ (138,950)	$ 3,506	79,107	(89,896)	81,548
Inventory Impairment, Results of Discounted Cash Flow Analysis							$ 109,000		1,700	131,700	4,200
Write Off Capitalized Interest and Capitalized Indirect Cost									1,200	16,900	2,300
Depreciation and amortization									15,640	14,759	13,807
Capital Expenditures									10,642	21,356	17,020
Assets	2,007,480				1,957,644				2,007,480	1,957,644
Operating Segments
Segment Reporting Information [Line Items]
Operating (loss) income									258,851	86,249	245,632
Depreciation and amortization									13,542	13,161	12,734
Corporate and unallocated
Segment Reporting Information [Line Items]
Operating (loss) income									(179,744)	(176,145)	(164,084)
Depreciation and amortization									2,098	1,598	1,073
Capital Expenditures									357	4,117	3,522
Assets	779,694				560,763				779,694	560,763
West
Segment Reporting Information [Line Items]
Total revenue									1,183,339	1,014,702	1,014,803
West | Operating Segments
Segment Reporting Information [Line Items]
Operating (loss) income									161,786	(5,492)	142,310
Depreciation and amortization									8,227	6,456	7,062
Capital Expenditures									5,063	11,635	8,152
Assets	658,909				751,110				658,909	751,110
East
Segment Reporting Information [Line Items]
Total revenue									477,624	514,961	524,563
East | Operating Segments
Segment Reporting Information [Line Items]
Operating (loss) income									56,319	51,576	57,372
Depreciation and amortization									2,458	3,250	2,619
Capital Expenditures									2,237	2,518	2,234
Assets	267,050				286,340				267,050	286,340
Southeast
Segment Reporting Information [Line Items]
Total revenue									466,114	558,076	567,767
Southeast | Operating Segments
Segment Reporting Information [Line Items]
Operating (loss) income									40,746	40,165	45,950
Depreciation and amortization									2,857	3,455	3,053
Capital Expenditures									2,985	3,086	$ 3,112
Assets	$ 301,827				$ 359,431				$ 301,827	$ 359,431