Partners' Capital of the Operating Partnership - At-The-Market Stock Offering, Common Units and Accrued Distributions (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
Accrued distributions
Accrued distributions	$ 65,009	$ 64,850
Operating Partnership
General Partners' Capital Account
Ownership interest (percent)	99.10%	99.00%
Kilroy Realty L.P.
Accrued distributions
Accrued distributions	$ 65,009	$ 64,850
Kilroy Realty L.P. \| Restricted Stock Units (RSUs)
Accrued distributions
Accrued distributions	$ 476	$ 484
RSUs (in shares)	846,072	861,385
Kilroy Realty L.P. \| Market measure-based Restricted Stock Units (RSUs)
Accrued distributions
Number of RSUs outstanding (in shares)	1,394,111	926,695
Kilroy Realty L.P. \| Partners’ Capital
Accrued distributions
Accrued distributions	$ 65,009	$ 64,850
Kilroy Realty L.P. \| Partners capital general partner
Accrued distributions
Accrued distributions	63,921	63,745
Kilroy Realty L.P. \| Partners capital limited partner
Accrued distributions
Accrued distributions	$ 612	$ 621
Non-Affiliated Investors \| Operating Partnership
General Partners' Capital Account
Ownership interest (percent)	0.90%	1.00%
Common Units \| Kilroy Realty L.P.
General Partners' Capital Account
Company owned common units in the Operating Partnership (in shares)	118,372,451	118,046,674
Non-affiliated investors and other common units of the Operating Partnership (in shares)	1,133,562	1,150,574
Common Units \| Non-Affiliated Investors
General Partners' Capital Account
Non-affiliated investors and other common units of the Operating Partnership (in shares)	1,133,562	1,150,574

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

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