Loans Payable and Secured Lines of Credit (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Interest expense	$ 644	$ 553	$ 1,832	$ 1,549
Interest capitalized	(562)	(486)	(1,602)	(1,438)
Interest income	(102)	(55)	(141)	(194)
Interest (income) expense, net	$ (20)	$ 12	$ 89	$ (83)

Amount of interest costs capitalized disclosed as an adjusting item to interest costs incurred.

No definition available.

Name:	us-gaap_InterestCostsCapitalizedAdjustment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total interest costs incurred during the period and either capitalized or charged against earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

+ Details

Name:	us-gaap_InterestCostsIncurred
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net amount of operating interest income (expense).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.10)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of interest income earned from interest bearing assets classified as other.

+ References

No definition available.

+ Details

Name:	us-gaap_InterestIncomeOther
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration