Concentration of Revenue (Details) - Tenants [Member] - United States Government [Member] |
12 Months Ended | ||
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Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Rental revenue [Member] | |||
| Concentration Risk | |||
| Percentage of revenue | 21.00% | 20.00% | 18.00% |
| Construction contract revenue [Member] | |||
| Concentration Risk | |||
| Percentage of revenue | 87.00% | ||
| Construction contract revenue [Member] | Minimum [Member] | |||
| Concentration Risk | |||
| Percentage of revenue | 90.00% | 90.00% | |
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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. No definition available.
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- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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