Document and Entity Information Document (USD $)	12 Months Ended
	Dec. 31, 2012	Feb. 11, 2013	Jun. 30, 2012
Entity Information [Line Items]
Entity Registrant Name	KILROY REALTY CORP
Entity Central Index Key	0001025996
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q4
Amendment Flag	false
Entity Common Stock, Shares Outstanding		74,895,990
Entity Public Float			$ 2,382,187,648
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Kilroy Realty, L.P. [Member]
Entity Information [Line Items]
Entity Registrant Name	Kilroy Realty, L.P.
Entity Central Index Key	0001493976
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q4
Amendment Flag	false
Entity Public Float			$ 12,415,519
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes