Notes Payable Notes Payable - Financial Services Textual (Details) - Financial Services [Member] - USD ($)	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Mortgage repurchase facility, current capacity	$ 600,000,000
Mortgage repurchase facility, maximum borrowing capacity	1,000,000,000
Mortgage loans held for sale pledged under repurchase agreement	540,100,000
Mortgage loans held for sale pledged under repurchase agreement, collateral value	520,000,000
Advance pay downs on mortgage repurchase facility	100,000,000
Mortgage repurchase facility	$ 420,000,000	$ 473,000,000
Interest rate on mortgage repurchase facility	3.30%
Weighted Average [Member]
Debt Instrument [Line Items]
Mortgage repurchase facility, current capacity	$ 725,000,000
Maximum [Member]
Debt Instrument [Line Items]
Mortgage repurchase facility, current capacity	$ 800,000,000

The amount paid on the mortgage repurchase facility to fund future mortgage repurchases by the company.

No definition available.

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- Definition

Interest rate on the 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.

+ References

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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- Definition

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.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

The aggregate amount of the participating mortgage obligation at the end of the accounting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=29639217&loc=d3e10013-112621

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- Definition

The carrying amount, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of repurchase obligations, and for which the transferee is not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=64858031&loc=SL6224234-111729

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