Secured and Unsecured Debt of the Operating Partnership - Unsecured Senior Notes, Unsecured Revolving Credit Facility and Term Loan Facility (Details)	6 Months Ended	12 Months Ended
Jun. 30, 2025 USD ($) extension_option	Dec. 31, 2024 USD ($) extension_option
Terms of the Borrowing Facilities
Unamortized deferred financing costs	$ 10,921,000	$ 12,692,000
Kilroy Realty L.P. \| Revolving Credit Facility and Term Loan Facility \| Adjusted SOFR \| Unsecured Revolving Credit Facility
Terms of the Borrowing Facilities
Variable rate (percent)	0.10%	0.10%
Kilroy Realty L.P. \| Revolving Credit Facility \| Unsecured Revolving Credit Facility
Terms of the Borrowing Facilities
Outstanding borrowings	$ 0	$ 0
Remaining borrowing capacity	1,100,000,000	1,100,000,000
Total borrowing capacity	$ 1,100,000,000	$ 1,100,000,000
Interest rate (percent)	5.65%	5.69%
Facility fee-annual rate (percent)	0.25%	0.25%
Unamortized deferred financing costs	$ 10,921,000	$ 12,692,000
Outstanding letters of credit	5,200,000	5,200,000
Contingent additional borrowings	$ 500,000,000.0	$ 500,000,000.0
Reduction interest rate	0.01%	0.01%
Number of extension options \| extension_option	2	2
Extension period (in months)	6 months	6 months
Kilroy Realty L.P. \| Revolving Credit Facility \| SOFR \| Unsecured Revolving Credit Facility
Terms of the Borrowing Facilities
Variable rate (percent)	1.10%	1.10%
Kilroy Realty L.P. \| Term Loan Facility \| SOFR \| 2024 Term Loan Facility
Terms of the Borrowing Facilities
Variable rate (percent)	1.20%	1.20%
Kilroy Realty L.P. \| Line of Credit \| 2024 Term Loan Facility
Terms of the Borrowing Facilities
Outstanding borrowings	$ 200,000,000	$ 200,000,000
Interest rate (percent)	5.62%	5.70%
Unamortized deferred financing costs	$ 419,000	$ 1,229,000
Contingent additional borrowings	$ 130,000,000.0	$ 130,000,000.0
Kilroy Realty L.P. \| Unsecured debt, net \| 2024 Term Loan Facility
Terms of the Borrowing Facilities
Number of extension options \| extension_option	2
Extension period (in months)	12 months	12 months

Debt Instrument, Contingent Additional Borrowings

No definition available.

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Namespace Prefix:	krc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instrument, Reduction Interest Rate

+ References

No definition available.

+ Details

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- Definition

Line of Credit, Extension Period

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Line of Credit, Number of Extension Options

+ References

No definition available.

+ Details

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Namespace Prefix:	krc_
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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 605
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-15

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-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477548/944-605-55-12

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Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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Period Type:	instant

- References

No definition available.

+ Details

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Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate at the end of the reporting period.

+ References

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-SubTopic 10
-Name Accounting Standards Codification
-Section S99
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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)
-Publisher FASB
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Balance Type:	credit
Period Type:	instant

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

No definition available.

+ Details

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