Contingencies - Warranty (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) home Community	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($) home
Loss Contingencies [Line Items]
Standard product warranty length, minimum			1 year
Standard product warranty length, maximum			2 years
Limited product warranty length			5 years
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 28,794,000	$ 12,561,000	$ 16,084,000	$ 11,663,000	$ 13,781,000	$ 11,663,000
Accruals for warranties issued	2,935,000	1,517,000	6,090,000	3,687,000
Changes in liability related to warranties existing in prior periods	7,058,000	2,459,000	27,813,000	5,682,000
Payments made (b)	(7,963,000)	(2,756,000)	(19,163,000)	(7,251,000)
Balance at end of period	30,824,000	$ 13,781,000	30,824,000	$ 13,781,000	30,824,000	16,084,000
Insurance Recoveries	7,300,000		13,000,000
Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Product warranty expense					28,900,000
FLORIDA
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period			$ 4,000,000
Balance at end of period						$ 4,000,000
Homes likely to require more than minor repairs | home			486			135
Product warranty accrual, warranties issued						$ 4,300,000
Homes repaired during period | home			116			11
Product warranty accrual, payments	(4,500,000)		$ (9,200,000)			$ (300,000)
Number of homes requiring more than minor repairs accounted for in warranty liability | home						124
Insurance Recoveries	6,100,000		10,400,000
FLORIDA | Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Product warranty expense	$ 6,100,000		$ 24,000,000		28,300,000
NEW JERSEY | Specific Warranty Issue
Movement in Standard Product Warranty Accrual [Roll Forward]
Standard product warranty			8 years
Product warranty expense					$ 600,000
Number of Communities With Water Intrusion Issues			1		1