Capitalized Interest (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Rollforward of capitalized interest
Capitalized interest, beginning of period	$ 183.7		$ 103.8		$ 137.1		$ 82.3
Interest incurred	45.1	[1]	44.4	[1]	144.0	[1]	125.5	[1]
Interest expensed:
Directly to interest expense	0		0		0		(7.1)
Amortized to cost of sales	(34.2)		(28.6)		(86.5)		(81.1)
Capitalized Interest Costs Written Off With Inventory Impairments	(1.1)		0		(1.1)		0
Capitalized interest, end of period	193.5		119.6		193.5		119.6
Financial Services [Member]
Rollforward of capitalized interest
Interest incurred	$ 1.2		$ 1.4		$ 3.0		$ 3.4

[1] Interest incurred includes interest incurred on the Company's financial services mortgage repurchase facility of $1.2 million and $3.0 million in the three and nine months ended June 30, 2014, respectively, and $1.4 million and $3.4 million in the same periods of 2013.