Supplemental Cash Flow Information (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Supplemental disclosure of non-cash activity:
Decrease in obligations related to land not owned under option agreements	$ (1,717)	$ (154)	$ (602)
Decrease in future land purchase rights	0	0	(11,651)
Contribution of future land purchase rights to unconsolidated entities	0	0	11,651
Decrease in debt related to conversion of Mandatory Convertible Subordinated Notes and Tangible Equity Units for common stock	(2,376)	(9,402)	(55,308)
Contribution of Pre-Owned net assets for investment in unconsolidated entity	0	0	(19,670)
Sale of interest in REIT for shares of AMH	26,040	0	0
Purchase of AMH shares in exchange for interest in REIT	(26,040)	0	0
Non-cash land acquisitions	20,274	11,000	7,813
Issuance of stock under deferred bonus stock plans	103	68	0
Supplemental disclosure of cash activity:
Interest payments	117,501	102,716	126,313
Income tax payments	212	403	831
Tax refunds received	$ 33,271	$ 6,730	$ 2,568