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Mortgage Notes Payable (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Sep. 01, 2016	Apr. 11, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Repayments of Secured Debt					$ 1,323,284	$ 20,137
Gains (Losses) on Extinguishment of Debt			$ (371)	$ 0	$ (371)	$ 0
Fountain Square [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt		$ 211,300
Coupon/Stated Rate		5.71%
599 Lexington Avenue [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt	$ 750,000
Coupon/Stated Rate	5.57%
Effective Rate	5.41%
Gains (Losses) on Extinguishment of Debt	$ 400
Embarcadero Center Four [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Repayments of Secured Debt	$ 344,800
Coupon/Stated Rate	6.10%
Effective Rate	7.02%
Gains (Losses) on Extinguishment of Debt	$ (700)

X

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ 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

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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
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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629

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The cash outflow to repay long-term debt that is wholly or partially secured by collateral. Excludes repayments of tax exempt secured debt.

+ References

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