Secured and Unsecured Debt of the Operating Partnership - Debt Maturities (Details) $ in Thousands	Dec. 31, 2016 USD ($)
Stated debt maturities and scheduled amortization payments, excluding debt discounts
Debt premium	$ 4,400
Kilroy Realty, L.P. [Member]
Stated debt maturities and scheduled amortization payments, excluding debt discounts
2017	7,286
2018	451,669
2019	265,309
2020	255,137
2021	5,342
Thereafter	1,349,023
Total	2,333,766
Unamortized debt issuance expense	(11,500)
Unsecured senior notes [Member] \| Kilroy Realty, L.P. [Member]
Stated debt maturities and scheduled amortization payments, excluding debt discounts
Unamortized discount	(6,600)
Secured debt [Member] \| Kilroy Realty, L.P. [Member]
Stated debt maturities and scheduled amortization payments, excluding debt discounts
Debt premium	$ 4,400

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Amount, after accumulated amortization, of debt discount.

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-SubTopic 30
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Amount, after accumulated amortization, of debt premium.

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Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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