Notes Payable (Details) - USD ($) $ in Millions	Jun. 30, 2017	Sep. 30, 2016
Unsecured:
Notes payable	$ 2,926.5	$ 3,271.3
Homebuilding [Member]
Unsecured:
Notes payable	2,453.1	2,798.3
Financial Services and Other [Member]
Unsecured:
Mortgage repurchase facility	$ 473.4	473.0
4.75% senior notes due 2017 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.75%
3.625% senior notes due 2018 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	3.625%
3.75% senior notes due 2019 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	3.75%
4.0% senior notes due 2020 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.00%
4.375% senior notes due 2022 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.375%
4.75% senior notes due 2023 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.75%
5.75% senior notes due 2023 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	5.75%
Line of Credit [Member] \| Homebuilding [Member]
Unsecured:
Revolving credit facility, maturing 2020	$ 0.0	0.0
Unsecured Debt [Member] \| 4.75% senior notes due 2017 [Member] \| Homebuilding [Member]
Unsecured:
Stated interest rate	4.75%
Notes payable	$ 0.0	349.5
Unsecured Debt [Member] \| 3.625% senior notes due 2018 [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	399.5	398.9
Unsecured Debt [Member] \| 3.75% senior notes due 2019 [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	498.6	498.0
Unsecured Debt [Member] \| 4.0% senior notes due 2020 [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	497.7	497.1
Unsecured Debt [Member] \| 4.375% senior notes due 2022 [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	348.0	347.7
Unsecured Debt [Member] \| 4.75% senior notes due 2023 [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	298.3	298.2
Unsecured Debt [Member] \| 5.75% senior notes due 2023 [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	397.6	397.3
Secured Debt [Member] \| Homebuilding [Member]
Unsecured:
Notes payable	$ 13.4	$ 11.6

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

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

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
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+ 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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