Notes Payable (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Sep. 30, 2014
Unsecured:
Notes payable	$ 3,945.5us-gaap_NotesPayable	$ 3,682.8us-gaap_NotesPayable
Homebuilding [Member]
Unsecured:
Notes payable	3,548.0	3,323.6
Financial Services [Member]
Unsecured:
Assets Sold under Agreements to Repurchase, Repurchase Liability	397.5	359.2
Senior Note Seven [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	5.25%
Senior Note Twenty Six [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	3.625%
Senior Note Eight [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	5.625%
Senior Note Nine [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	6.50%
Senior Note Twenty Four [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.75%
Senior Note Twenty Nine [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	3.75%
Senior Note Member Thirty [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.00%
Senior Note Member Twenty Five [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.375%
Senior Note Twenty Seven [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.75%
SeniorNoteTwentyEight [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	5.75%
Unsecured Debt [Member] \| Senior Note Seven [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	0	157.7
Unsecured Debt [Member] \| Senior Note Twenty Six [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	400.0	400.0
Unsecured Debt [Member] \| Senior Note Eight [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	170.0	169.9
Unsecured Debt [Member] \| Senior Note Nine [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	372.6	372.6
Unsecured Debt [Member] \| Senior Note Twenty Four [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	350.0	350.0
Unsecured Debt [Member] \| Senior Note Twenty Nine [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	500.0	500.0
Unsecured Debt [Member] \| Senior Note Member Thirty [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	500.0	0
Unsecured Debt [Member] \| Senior Note Member Twenty Five [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	350.0	350.0
Unsecured Debt [Member] \| Senior Note Twenty Seven [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	300.0	300.0
Unsecured Debt [Member] \| SeniorNoteTwentyEight [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	400.0	400.0
Line of Credit [Member] \| Homebuilding [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Amount Outstanding	175.0	300.0
Secured Debt [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	$ 30.4	$ 23.4

Amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(m)(1)(i)(A)(ii))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseRepurchaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant