Summary of Significant Accounting Policies Business Acquisitions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended	12 Months Ended		3 Months Ended		3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2014 Crown Communities [Member]	Sep. 30, 2014 Crown Communities [Member]	May 31, 2014 Crown Communities [Member] Home Lot	Dec. 31, 2013 RegentHomes [Member]	Oct. 31, 2013 RegentHomes [Member] Lot Home	Sep. 30, 2012 Breland Homes [Member] Home Lot	Jun. 30, 2014 Southeast [Member] Crown Communities [Member]	Jun. 30, 2014 East [Member] Crown Communities [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory				$ 140.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				1.9
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets				4.9
Goodwill, Acquired During Period				53.6						34.1	19.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				11.7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				(3.0)
Payments to Acquire Businesses, Net of Cash Acquired	244.1	9.4	96.5	209.6			34.5		105.9
Business Acquisition, Number of Homes Acquired						640		240	300
Business Acquisition, Number of Finished Lots Acquired						2,350		300	1,000
Business Acquisition, Number of Lots Under Option Contracts						3,400		600	3,700
Business Acquisition, Sales Order Backlog Acquired (Homes)						431		213	228
Business Acquisition, Number of Homes Closed					721
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual					$ 187.7