Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Cost basis of real estate investments for federal income tax purposes for entities with a substantial portion of business acquiring and holding investment real estate.

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Schedule III - Real Estate and Accumulated Depreciation - Narrative (Details) $ in Thousands	Dec. 31, 2025 USD ($) property	Dec. 31, 2024 USD ($)
Real Estate and Accumulated Depreciation [Line Items]
Deferred financing costs, net	$ 9,150	$ 12,692
Investment in real estate, federal Income tax basis	10,600,000
Kilroy Realty L.P.
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	4,625,442
Kilroy Realty L.P. \| Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Deferred financing costs, net	7,757	8,489
3.57% Mortgage Payable due December 2026 \| Kilroy Realty L.P.
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	148,800
3.57% Mortgage Payable due December 2026 \| Kilroy Realty L.P. \| Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	148,815	152,668
4.48% Mortgage Payable due July 2027 \| Kilroy Realty L.P. \| Secured debt
Real Estate and Accumulated Depreciation [Line Items]
Long-term debt, gross	76,627	79,020
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	$ 375,000
Office Building
Real Estate and Accumulated Depreciation [Line Items]
Deferred financing costs, net	$ 7,800
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