Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) lease	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of properties subject to ground leases \| lease	1
Ground leases, rent expense	$ 33	$ 40	$ 23
Non-cancelable operating lease, rent expense	1,411	$ 1,415	$ 1,385
Ground lease, future minimum lease obligations
2018	23
2019	23
2020	23
2021	23
2022	23
Thereafter	608
Total	723
Office space
2018	640
2019	463
2020	586
2021	441
2022	445
Thereafter	931
Total	3,506
Total
2018	663
2019	609
2020	464
2021	486
2022	468
Thereafter	1,539
Total	$ 4,229

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Amount of minimum lease payments for capital leases.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84164817&loc=d3e45280-112737

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Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

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Number of separate real estate development properties located on land subject to ground leases.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 40
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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