Secured and Unsecured Debt of the Operating Partnership - Debt Maturities (Details) - Kilroy Realty L.P. [Member] $ in Thousands	Dec. 31, 2020 USD ($)
Stated debt maturities and scheduled amortization payments, excluding debt discounts
2021	$ 5,342
2022	5,554
2023	305,775
2024	431,006
2025	406,246
Thereafter	2,800,442
Total aggregate principal value	3,954,365
Unamortized debt issuance expense	(22,400)
Unsecured senior notes [Member]
Stated debt maturities and scheduled amortization payments, excluding debt discounts
Debt issuance discount	$ (8,300)

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.

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Amount, after accumulated amortization, of debt discount.

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Amount of long-term debt payable, sinking fund requirement, and other securities issued that are redeemable by holder at fixed or determinable price and date, maturing after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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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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