Summary of Significant Accounting Policies Variable interest entities and unconsolidated joint ventures (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Increase (decrease) in investments in joint venture arrangements	$ (7,491)
Distribution of single-family lots from joint venture arrangements	16,600	$ 28,130	$ 8,236
Investment in joint venture arrangements	(12,088)	(21,746)	$ (18,162)
Investment in joint venture arrangements	$ 20,525	$ 28,016
Minimum [Member]
Variable Interest Entity [Line Items]
Discount Rate Used in Determining Fair Value of land and lots	13.00%	13.00%
Equity Method Investment, Ownership Percentage	25.00%	25.00%
Maximum [Member]
Variable Interest Entity [Line Items]
Discount Rate Used in Determining Fair Value of land and lots	16.00%	16.00%
Equity Method Investment, Ownership Percentage	97.00%	74.00%

Discount Rate Used in Determining Fair Value of land/lots

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- Definition

Distribution of single-family lots from unconsolidated LLC's

+ References

No definition available.

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- Definition

Increase (decrease) in investments in unconsolidated joint ventures and other similar arrangements

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The cash outflow associated with the acquisition of or advances to an entity that is related to it but not strictly controlled (for example, an unconsolidated subsidiary, affiliate, and joint venture or equity method investment) or the acquisition of an additional interest in a subsidiary (controlled entity).

+ 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

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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.

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No definition available.

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