Noncontrolling Interests on the Company's Consolidated Financial Statements (Details) $ / shares in Units, $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2022 USD ($) trading_day $ / shares shares	Sep. 30, 2021 shares	Dec. 31, 2021 USD ($) trading_day $ / shares shares
Noncontrolling Interest [Line Items]
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01		$ 0.01
Number of trading days \| trading_day	10		10
Aggregate value upon redemption of outstanding noncontrolling common units \| $	$ 50.5		$ 76.2
Non-Affiliated Investors \| Common Units
Noncontrolling Interest [Line Items]
Common units outstanding held by common limited partners (in shares)	1,150,574	1,150,574	1,150,574
Kilroy Realty L.P. \| Common Units
Noncontrolling Interest [Line Items]
Conversion ratio	1
Kilroy Realty L.P. \| Common Units
Noncontrolling Interest [Line Items]
Common units outstanding held by common limited partners (in shares)	1,150,574		1,150,574
Operating Partnership
Noncontrolling Interest [Line Items]
Ownership interest (percent)	99.00%	99.00%	99.00%
Operating Partnership \| Non-Affiliated Investors
Noncontrolling Interest [Line Items]
Ownership interest (percent)	1.00%	1.00%	1.00%

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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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