Contingencies - Warranty (Details) $ in Thousands	3 Months Ended		6 Months Ended		30 Months Ended
	Mar. 31, 2017 USD ($) home	Mar. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) home	Mar. 31, 2016 USD ($)	Mar. 31, 2017 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	$ 32,309	$ 28,913	$ 39,131	$ 27,681
Accruals for warranties issued	3,249	3,086	5,907	5,701
Changes in liability related to warranties existing in prior periods	2,463	20,053	7,855	30,653
Payments made	(12,635)	(11,149)	(27,507)	(23,132)
Balance at end of period	25,386	40,903	25,386	40,903	$ 25,386
Insurance recoveries	2,300	19,800	6,200	36,200
Excess insurance recovery		3,600		3,600
Specific Warranty Issue | Florida
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period			22,600
Balance at end of period	11,400		11,400		11,400
Product warranty expense	$ 1,500	$ 19,600	$ 6,100	$ 28,600	$ 84,700
Homes likely to require more than minor repairs | home	705		705		705
Movement on number of homes likely to be repaired | home			15
Homes have been repaired | home	550		550		550
Product warranty accrual, payments	$ 7,300		$ 17,300
Estimated remaining warranty costs	$ 4,100		$ 4,100		$ 4,100