Contingencies - Narrative (Details) $ in Thousands	12 Months Ended			39 Months Ended
	Sep. 30, 2017 USD ($) home	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2017 USD ($) home	Sep. 30, 2014 USD ($)
Loss Contingencies [Line Items]
Limited product warranty length	10 years
Accrued warranty expenses	$ 18,091	$ 39,131	$ 27,681	$ 18,091	$ 16,084
Insurance recoveries	4,800	59,300
Excess insurance recovery		3,600
Accrued amounts for litigation and other contingent liabilities	3,900	10,200		3,900
DPA Liability
Loss Contingencies [Line Items]
Damages paid	33,500
Expense related to DPA and HUD agreements		4,900	$ 5,300
Specific Warranty Issue
Loss Contingencies [Line Items]
Product warranty expense				85,600
Specific Warranty Issue | Florida
Loss Contingencies [Line Items]
Product warranty expense	5,200	48,000
Accrued warranty expenses	$ 4,700	22,600		$ 4,700
Numer of homes likely to require more than minor repairs | home	710			710
Change on number of homes likely to be repaired | home	20
Number of homes that have been repaired | home	640			640
Accrued product warranty, decrease for payments	$ 23,100
Estimated remaining warranty costs	2,500			$ 2,500
Performance Bonds
Loss Contingencies [Line Items]
Letters of credit secured using cash collateral	45,500			45,500
Cash collateral in restricted accounts securing letters of credit	200,600			200,600
Land Option Contracts
Loss Contingencies [Line Items]
Letters of credit secured using cash collateral	$ 11,000			$ 11,000
Minimum
Loss Contingencies [Line Items]
Standard product warranty period	1 year
Maximum
Loss Contingencies [Line Items]
Standard product warranty period	2 years
Settled Litigation | Insurance Settlement
Loss Contingencies [Line Items]
Insurance recoveries		$ 15,500