Secured and Unsecured Debt of the Operating Partnership - Debt Maturities (Details) - Kilroy Realty L.P. [Member] $ in Thousands	Mar. 31, 2021 USD ($)
Stated debt maturities and scheduled amortization payments
Remaining 2021	$ 4,026
2022	5,554
2023	305,775
2024	431,006
2025	406,246
2026	401,317
Thereafter	2,399,125
Total debt	3,953,049
Unsecured term loan facility, unsecured senior notes and secured debt [Member]
Stated debt maturities and scheduled amortization payments
Unamortized deferred financing costs	21,700
Unsecured senior notes [Member]
Stated debt maturities and scheduled amortization payments
Unamortized discount	$ 8,000

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 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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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 in second 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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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 in remainder of current fiscal year.

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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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