Interest - Schedule of Capitalized Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Real Estate Inventory, Capitalized Interest Costs [Roll Forward]
Capitalized interest in inventory, beginning of period	$ 113,414	$ 134,693	$ 119,659	$ 136,565
Interest incurred	19,270	23,012	58,517	66,839
Capitalized interest impaired	0	(792)	0	(792)
Interest expense not qualified for capitalization and included as other expense	(212)	(3,003)	(2,781)	(6,373)
Capitalized interest amortized to home construction and land sales expenses	(22,529)	(21,814)	(65,452)	(64,143)
Capitalized interest in inventory, end of period	$ 109,943	$ 132,096	$ 109,943	$ 132,096