Secured and Unsecured Debt of the Operating Partnership - Unsecured Senior Notes - Registered Offerings and Private Placement (Details) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 12, 2024
Debt Instrument [Line Items]
Loss on early extinguishment of debt		$ 0	$ 0	$ 12,246,000
Repurchases of unsecured debt		20,584,000	0	0
Kilroy Realty L.P.
Debt Instrument [Line Items]
Loss on early extinguishment of debt		0	$ 0	$ 12,246,000
Long-term debt, gross		$ 4,961,406,000
Kilroy Realty L.P. | Unsecured debt | 3.800% Unsecured Senior Notes Due 2023
Debt Instrument [Line Items]
Stated interest rate	3.80%
Debt redemption, principal amount	$ 300,000,000
Loss on early extinguishment of debt	(12,200,000)
Premium paid to the note holders at the redemption date	12,100,000
Write-off of unamortized discount and unamortized deferred financing costs	$ 100,000
Kilroy Realty L.P. | Unsecured debt | 3.450% Unsecured Senior Notes Due 2024
Debt Instrument [Line Items]
Stated interest rate		3.45%
Repurchases of unsecured debt		$ 21,300,000
Principal amount of debt		425,000,000
Long-term debt, gross		$ 403,712,000
Kilroy Realty L.P. | Unsecured debt | 6.250% Unsecured Senior Notes Due 2036 | Subsequent event
Debt Instrument [Line Items]
Stated interest rate					6.25%
Principal amount of debt					$ 400,000,000