Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2013
Deferred tax assets:
Inventory costs	$ 88.6	$ 74.5
Inventory impairments	234.7	267.6
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Warranty Reserves	117.3	114.5
Net operating loss carryforwards	84.5	99.3
Tax credit carryforwards	7.6	5.9
Incentive compensation plans	69.3	69.9
Deferral of profit on home sales	1.9	1.9
Other	19.9	21.5
Total deferred tax assets	623.8	655.1
Valuation allowance	(31.1)	(31.0)	(23.2)
Total deferred tax assets, net of valuation allowance	592.7	624.1
Deferred Tax Liabilities, Gross	27.7	37.5
Deferred income taxes, net	565.0	586.6
State and Local Jurisdiction [Member] | Tax Credit Carryforward Amount to Expire [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	5.7
State and Local Jurisdiction [Member] | Tax Credit Carryforward Amount with No Expiration [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 1.9