v3.3.1.900

Basis of Presentation and Significant Accounting Policies (Details) | 12 Months Ended
--- | ---
Dec. 31, 2015 USD ($) building project | Dec. 31, 2014 USD ($) building property | Dec. 31, 2013 USD ($) building | Dec. 31, 2011
Basis of presentation and significant accounting policies [Line Items] |  |  |  |
Proceeds from Sale of Real Estate Held-for-investment | $ 319,639,000 | $ 427,544,000 | $ 21,178,000 |
Number of Real Estate Properties Sold | building | 10 | 17 | 3 |
Amortization of Financing Costs | $ 12,300,000 | $ 12,200,000 |  |
Number of real estate properties | 2 | 5 |  |
REIT annual taxable income distribution requirement percentage | 90.00% |  |  | 90.00%
Company annual taxable income distribution | 100.00% |  |  |
Concentration Risk of Significant Tenants, Percentage | 36.90% |  |  |
Cash, FDIC Insured Amount | $ 250,000 |  |  |
Kilroy Realty Finance, Inc. [Member] |  |  |  |
Basis of presentation and significant accounting policies [Line Items] |  |  |  |
Percentage of General partnership interest owned by wholly-owned subsidiary of the Company | 1.00% |  |  |
Torrey Santa Fe Properties [Member] |  |  |  |
Basis of presentation and significant accounting policies [Line Items] |  |  |  |
Number of real estate properties | project | 4 |  |  |
Carlsbad Oaks [Member] |  |  |  |
Basis of presentation and significant accounting policies [Line Items] |  |  |  |
Number of real estate properties | project | 1 |  |  |

X
- Definition Basis of presentation and significant accounting policies [Line Items] + References No definition available. + Details
Name: | krc_BasisOfPresentationAndSignificantAccountingPoliciesLineItems
Namespace Prefix: | krc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Company annual taxable income distribution + References No definition available. + Details
Name: | krc_CompanyAnnualTaxableIncomeDistribution
Namespace Prefix: | krc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of Real Estate Properties Sold + References No definition available. + Details
Name: | krc_NumberofRealEstatePropertiesSold
Namespace Prefix: | krc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition REIT annual taxable income distribution requirement percentage + References No definition available. + Details
Name: | krc_ReitAnnualTaxableIncomeDistributionRequirementPercentage
Namespace Prefix: | krc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of noncash expense included in interest expense to issue debt and obtain financing associated with the related debt instruments. Alternate captions include noncash interest expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 8 -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 8 -Article 9 + Details
Name: | us-gaap_AmortizationOfFinancingCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The amount of cash deposited in financial institutions as of the balance sheet date that is insured by the Federal Deposit Insurance Corporation. + References No definition available. + Details
Name: | us-gaap_CashFDICInsuredAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6351-108592 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13531-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 275 -SubTopic 10 -Section 50 -Paragraph 20 -URI http://asc.fasb.org/extlink&oid=6927468&loc=d3e6404-108592 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 21 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13537-108611 + Details
Name: | us-gaap_ConcentrationRiskPercentage1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055 + Details
Name: | us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of real estate properties owned as of the balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfRealEstateProperties
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Cash received from the sale of real estate that is held for investment, that is, it is part of an investing activity during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=krc_KilroyRealtyFinanceInc.Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=krc_TorreySantaFePropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=krc_CarlsbadOaksMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |