Acquisitions (Details Textuals) $ in Thousands		1 Months Ended	12 Months Ended
		Oct. 23, 2014 USD ($) shares	Dec. 31, 2015 USD ($) building	Dec. 31, 2014 USD ($) building property	Dec. 31, 2013 USD ($)	Jul. 01, 2015 shares	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)
Business Acquisition [Line Items]
Number of buildings			2	5
Outstanding principal balance				$ 172,500
Initial premium on outstanding amount of secured debt							$ 6,200
Revenues			$ 7,700
Net income			2,800
Below-market leases acquired				$ 7,000
Weighted average amortization period of below-market leases				6 years 1 month
Accounts Payable and Accrued Liabilities			246,323	$ 225,830
Common stock, shares issued | shares						3,773,766
purchase price, value of shares issued to acquire land			0	$ 21,631	$ 0
Kilroy Mission Bay [Member]
Business Acquisition [Line Items]
Accounts Payable and Accrued Liabilities								$ 2,300
Office Properties Acquisitions [Member]
Business Acquisition [Line Items]
Number of buildings | building				5
Purchase price	[1],[2]			$ 206,600
In-place leases, above-market leases, and leasing commissions acquired	[3],[4]			17,259
Deferred revenue and acquisition-related intangible liabilities	[4],[5]			$ 6,990
320 & 321 Westlake Terry, Seattle WA [Member]
Business Acquisition [Line Items]
Number of buildings | building				1
Purchase price	[1]			$ 106,100
12780 and 12790 El Camino Real, Sandiego, CA [Member]
Business Acquisition [Line Items]
Number of buildings | building	[6]			4
Purchase price	[1],[6]			$ 100,500
SFFGA [Member]
Business Acquisition [Line Items]
Accounts Payable and Accrued Liabilities				13,400
Common stock, shares issued | shares		351,476
purchase price, value of shares issued to acquire land		$ 21,600
Secured Debt [Member]
Business Acquisition [Line Items]
Initial premium on outstanding amount of secured debt			6,200
In-Place Leases [Member]
Business Acquisition [Line Items]
In-place leases, above-market leases, and leasing commissions acquired				$ 12,300
Weighted average amortization period of above-market leases in years				7 years
Deferred Leasing Costs [Member]
Business Acquisition [Line Items]
In-place leases, above-market leases, and leasing commissions acquired				$ 4,900
Weighted average amortization period of above-market leases in years				7 years
Kilroy Realty, L.P. [Member]
Business Acquisition [Line Items]
Accounts Payable and Accrued Liabilities			246,323	$ 225,830
Kilroy Realty, L.P. [Member] | 6.05% Mortgage Payable Due June 1, 2019 [Member] | Secured Debt [Member]
Business Acquisition [Line Items]
Initial premium on outstanding amount of secured debt			$ 6,200	$ 8,000

[1] Excludes acquisition-related costs and non-lease related accrued liabilities assumed. Includes assumed unpaid leasing commissions and tenant improvements.

[2] The results of operations for the properties acquired during 2014 contributed $7.7 million and $2.8 million to revenues and net income from continuing operations, respectively, for the year ended December 31, 2014.

[3] Represents in-place leases (approximately $12.3 million with a weighted average amortization period of 7.0 years) and leasing commissions (approximately $4.9 million with a weighted average amortization period of 7.0 years).

[4] purchase price of the two acquisitions completed during the year ended December 31, 2014 were individually less than 5% and in aggregate less than 10% of the Company’s total assets as of December 31, 2014.(2)

[5] Represents below-market leases (approximately $7.0 million with a weighted average amortization period of 6.1 years).

[6] As of December 31, 2014, these properties, together the “Chesapeake Commons” project, were temporarily being held in a separate VIE to facilitate potential Section 1031 Exchanges. During January 2015, the Company closed out the Section 1031 Exchange related to this VIE.