Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 428,539	$ 417,804
Customer deposits	22,917		$ 18,937
Contract with customer, liability, revenue recognized	8,300
Homebuilding revenue
Disaggregation of Revenue [Line Items]
Total revenue	424,229	417,399
Land sales and other revenue
Disaggregation of Revenue [Line Items]
Total revenue	$ 4,310	$ 405