Contingencies - Warranty (Details) $ in Thousands	3 Months Ended		9 Months Ended		45 Months Ended
	Jun. 30, 2018 USD ($) home	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) home	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) home
Loss Contingencies [Line Items]
Standard product warranty length, minimum			1 year
Standard product warranty length, maximum			2 years
Limited product warranty length (up to)			10 years
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 14,583	$ 25,386	$ 18,091	$ 39,131
Accruals for warranties issued	3,254	3,727	10,758	9,549
Changes in liability related to warranties existing in prior periods	711	(1,293)	(2,574)	6,581
Payments made	(3,258)	(7,998)	(10,985)	(35,439)
Balance at end of period	15,290	19,822	15,290	19,822	$ 15,290
Insurance recoveries	200	$ 600	200	$ 5,600
Florida
Movement in Standard Product Warranty Accrual [Roll Forward]
Insurance recoveries			82,800
Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Product warranty expense					85,100
Specific Warranty Issue | Florida
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at end of period	2,100		2,100		$ 2,100
Decrease in warranty reserves	$ 100		$ (500)
Homes likely to require more than minor repairs | home	708		708		708
Homes have been repaired | home	682		682		682
Product warranty accrual, payments	$ 400		$ 2,100
Estimated remaining warranty costs	$ 2,300		$ 2,300		$ 2,300