Basis of Presentation and Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total revenue	$ 421,260	$ 455,178	$ 823,300	$ 827,667
Customer deposits	16,232		16,232		$ 14,903
Contract with customer, liability, revenue recognized	4,000		12,400
Homebuilding revenue
Disaggregation of Revenue [Line Items]
Total revenue	420,945	441,115	821,927	808,869
Land sales and other revenue
Disaggregation of Revenue [Line Items]
Total revenue	$ 315	$ 14,063	$ 1,373	$ 18,798