Secured and Unsecured Debt of the Operating Partnership - Additional Information (Details) - Kilroy Realty L.P. [Member] - Revolving credit facility [Member]	1 Months Ended
Apr. 29, 2021 USD ($) extensionOption	Sep. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Maximum borrowing capacity \| $	$ 1,100,000,000	$ 1,100,000,000	$ 750,000,000
Number of extension options \| extensionOption	2
Extension period	6 months
Interest rate reduction if sustainability performance targets met (percent)	0.01%

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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