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Subsequent Event (Details) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2016 USD ($) | Sep. 30, 2015 USD ($) | Oct. 05, 2017 Market State Projects
Subsequent Event [Line Items] |  |  |  |  |
Payments to Acquire Businesses, Net of Cash Acquired |  | $ 4.1 | $ 82.2 | $ 70.9 |
Forestar Group [Member] | Subsequent Event [Member] |  |  |  |  |
Subsequent Event [Line Items] |  |  |  |  |
Business Acquisition, Date of Acquisition Agreement | Oct. 05, 2017 |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired |  |  |  |  | 75.00%
Payments to Acquire Businesses, Net of Cash Acquired | $ 558.3 |  |  |  |
Number Of Housing Construction Markets | Market |  |  |  |  | 14
Number of States in which Entity Operates | State |  |  |  |  | 10
Number of Projects | Projects |  |  |  |  | 44

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- Definition The number of markets the entity operates in as of the balance sheet date. + References No definition available. + Details
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- Definition Number of Projects + References No definition available. + Details
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- Definition Date when the business acquisition agreement was executed, in CCYY-MM-DD format. + References No definition available. + Details
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- Definition Percentage of voting equity interests acquired at the acquisition date in the business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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- Definition The number of states the entity operates in as of the balance sheet date. + References No definition available. + Details
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- Definition The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
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- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
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- Details
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- Details
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