| Cover Page Cover Page | Jul. 28, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jul. 28, 2021 |
| Entity Registrant Name | KILROY REALTY CORP |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-12675 |
| Entity Tax Identification Number | 95-4598246 |
| Entity Central Index Key | 0001025996 |
| Amendment Flag | false |
| Entity Address, Address Line One | 12200 W. Olympic Boulevard |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | Los Angeles |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 90064 |
| City Area Code | 310 |
| Local Phone Number | 481-8400 |
| Title of 12(b) Security | Common Stock, $.01 par value |
| Security Exchange Name | NYSE |
| Trading Symbol | KRC |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
