Fair Value Measurements Fair Value Measurements - Level 3 Rollforward (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended				6 Months Ended						6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Homebuilding [Member]	Sep. 30, 2012 Homebuilding [Member]	Mar. 31, 2013 Homebuilding [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Sep. 30, 2012 Homebuilding [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Mar. 31, 2013 Financial Services [Member]	Sep. 30, 2012 Financial Services [Member]	Mar. 31, 2013 Financial Services [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Sep. 30, 2012 Financial Services [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Other Investments			$ 18.6	$ 0	$ 18.6	[1]	$ 0	[1]
Payments to Acquire Other Investments	18.6	0			18.6	[1]
Mortgage loans held for sale									394.3	345.3	5.7	[2]	0	[2]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings, Description	.4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	(2.6)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3											$ 7.9	[2]

[1] In October 2012, the Company purchased $18.6 million of defaulted debt securities which are secured by residential real estate. The Company intends to foreclose on the property or negotiate an agreement to obtain the right to take possession of the residential real estate in order to develop the property and ultimately build and sell homes. These securities, which are included in other assets on the consolidated balance sheets, are classified as available for sale and are carried at estimated fair value, which approximates their original transaction price.

[2] Mortgage loans held for sale are reflected at fair value. Interest income earned on mortgage loans held for sale is based on contractual interest rates and included in financial services interest and other income. Mortgage loans held for sale includes $5.7 million of loans originated under the fair value option which the Company has not sold into the secondary market, but plans to sell as market conditions permit. The fair value of these mortgage loans held for sale is generally calculated considering the secondary market and adjusted for the value of the underlying collateral, including interest rate risk, liquidity risk and prepayment risk; therefore, they were transferred from a Level 2 valuation to a Level 3 valuation during the six months ended March 31, 2013.