Secured and Unsecured Debt of the Operating Partnership - Unsecured Senior Notes - Private Placement (Details) - Kilroy Realty, L.P. [Member] - USD ($)	12 Months Ended
Dec. 31, 2016	Sep. 14, 2016
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,333,766,000
Unsecured debt [Member] \| 3.35% Series A Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 175,000,000
Stated interest rate		3.35%
Unsecured debt [Member] \| 3.45% Series B Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross		$ 75,000,000
Stated interest rate		3.45%
Unsecured debt [Member] \| Series A and B Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Operating partnership, payment percent	5.00%
Operating partnership, total payment percentage	100.00%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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