Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012
Deferred tax assets:
Inventory costs	$ 74.5		$ 68.4
Inventory impairments	267.6		323.4
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Warranty Reserves	114.5		116.7
Net operating loss carryforwards	99.3		188.9
Tax credit carryforwards	5.9		7.0
Incentive compensation plans	69.9		53.1
Deferral of profit on home sales	1.9		1.7
Other	21.5		31.8
Total deferred tax assets	655.1		791.0
Valuation allowance	(31.0)	(23.2)	(41.9)
Total deferred tax assets, net of valuation allowance	624.1		749.1
Deferred Tax Liabilities, Gross	37.5		39.6
Deferred income taxes, net	586.6		709.5
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards			85.2
State and Local Jurisdiction [Member] | Tax Credit Carryforward Amount to Expire [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	4.0
State and Local Jurisdiction [Member] | Tax Credit Carryforward Amount with No Expiration [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 1.9