Fair Value Measurements Fair Value Measurements - Level 3 Rollforward (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Homebuilding [Member]	Sep. 30, 2012 Homebuilding [Member]	Dec. 31, 2012 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]		Dec. 31, 2012 Financial Services [Member]	Sep. 30, 2012 Financial Services [Member]	Dec. 31, 2012 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
Mortgage loans held for sale									$ 307.9	$ 345.3	$ 7.7	[2]	$ 0	[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 and take possession of the residential real estate in order to develop the property and ultimately build and sell homes. These securities are classified as available for sale and are included in other assets in the Company's consolidated balance sheets. At December 31, 2012, the Company valued these securities at the recent October 2012 transaction price, which is considered to be the best initial estimate of fair value.

[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 $7.7 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 three months ended December 31, 2012.