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Mortgage Notes Payable (Parenthetical) (Detail) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2017 | Dec. 31, 2016
Executive Office Park [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Interest Rate Terms | Interest rate is subject to reset on July 1, 2018. |  | Interest rate is subject to reset on July 1, 2018. |
Fixed interest rate on mortgage (in hundredth) | 5.80% | [1] | 5.80% | [2]
Morena Office Center [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Interest Rate Terms | Interest rate is subject to reset on May 4, 2018. |  | Interest rate subject to resetting on the 6th loan anniversary. |
Fixed interest rate on mortgage (in hundredth) | 4.50% | [1] | 4.50% | [2]
Pacific Oaks Plaza [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Interest Rate Terms |  |  | Interest rate is subject to reset on April 28, 2017. |
Fixed interest rate on mortgage (in hundredth) | 4.50% | [1] | 4.50% | [2]
Shoreline Medical Building [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Interest Rate Terms |  |  | Interest rate subject to resetting on the 6th loan anniversary. |
Fixed interest rate on mortgage (in hundredth) | 5.10% | [1] | 5.10% | [2]
Bismarck Office Building [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt Instrument, Interest Rate Terms | Interest rate is subject to reset on September 1, 2023 and on September 1, 2030. |  | Interest rate is subject to reset on September 1, 2023. |
Fixed interest rate on mortgage (in hundredth) | 4.02% | [1] | 4.02% | [2]
Model Home Properties [Member] | Minimum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Fixed interest rate on mortgage (in hundredth) | 3.80% |  | 3.80% |
Model Home Properties [Member] | Maximum [Member] |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Fixed interest rate on mortgage (in hundredth) | 5.50% |  | 5.50% |
[1] | Interest rates as of September 30, 2017.
[2] | Interest rates as of December 31, 2016.

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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