Schedule III - Real Estate and Accumulated Depreciation - Narrative (Details) $ in Thousands	Dec. 31, 2023 USD ($) property	Dec. 31, 2022 USD ($)
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances	$ 612,694
Investment in real estate, federal Income tax basis	10,100,000
Kilroy Realty L.P.
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	4,961,406
Kilroy Realty L.P. | Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Unamortized debt issuance expense	9,469	$ 531
3.57% Mortgage Payable due December 2026 | Kilroy Realty L.P.
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	156,400
3.57% Mortgage Payable due December 2026 | Kilroy Realty L.P. | Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	156,386	159,973
4.48% Mortgage Payable due July 2027 | Kilroy Realty L.P. | Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	81,308	83,496
5.90% Mortgage Payable due August 2034 | Kilroy Realty L.P.
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	375,000
5.90% Mortgage Payable due August 2034 | Kilroy Realty L.P. | Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	375,000	$ 0
Office Building
Real Estate and Accumulated Depreciation [Line Items]
Unamortized debt issuance expense	$ 9,500
Office Building | Sunset Blvd., Gower St. and El Centro Ave. Properties in Los Angeles
Real Estate and Accumulated Depreciation [Line Items]
Number of buildings | property	5
Residential Tower | Sunset Blvd., Gower St. and El Centro Ave. Properties in Los Angeles
Real Estate and Accumulated Depreciation [Line Items]
Number of buildings | property	1
Building
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Tenant Improvements | Minimum
Real Estate and Accumulated Depreciation [Line Items]
Property depreciable lives	1 year
Tenant Improvements | Maximum
Real Estate and Accumulated Depreciation [Line Items]
Property depreciable lives	20 years