Unsecured Revolving Credit Facility (Details 3) (USD $)	3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Line of Credit Facility [Line Items]
Unsecured debt	$ 1,431,217,000		$ 1,431,132,000
Terms of the Credit Facility
Unsecured line of credit	0		45,000,000
Kilroy Realty, L.P. [Member]
Line of Credit Facility [Line Items]
Unsecured debt	1,431,217,000		1,431,132,000
Terms of the Credit Facility
Unsecured line of credit	0		45,000,000
Kilroy Realty, L.P. [Member] | Revolving Credit Facility [Member]
Terms of the Credit Facility
Unsecured line of credit	0		45,000,000
Remaining borrowing capacity	500,000,000		455,000,000
Total borrowing capacity	500,000,000	[1]	500,000,000	[1]
Interest rate	0.00%		1.62%	[2]
Facility fee - annual rate	0.30%	[3]
Maturity date	Apr. 03, 2017	[4]
Debt Instrument, Contingent Additional Borrowings	200,000,000
Debt Instrument, Basis Spread on Variable Rate	1.45%
Kilroy Realty, L.P. [Member] | Line of Credit [Member]
Terms of the Credit Facility
Unamortized Debt Issuance Cost	4,500,000
One Hundred Fifty Million Term Loan Facility [Member] | Kilroy Realty, L.P. [Member] | Line of Credit [Member]
Line of Credit Facility [Line Items]
Unsecured debt	150,000,000		150,000,000
Terms of the Credit Facility
Debt Instrument, Contingent Additional Borrowings	$ 100,000,000
Debt Instrument, Basis Spread on Variable Rate	1.75%

[1] We may elect to borrow, subject to bank approval and obtaining commitments for any additional borrowing capacity, up to an additional $200.0 million under an accordion feature under the terms of the revolving credit facility.

[2] The revolving credit facility interest rate was calculated based on an annual rate of LIBOR plus 1.450% as of both March 31, 2014 and December 31, 2013.

[3] The facility fee is paid on a quarterly basis and is calculated based on the total borrowing capacity. In addition to the facility fee, from 2010 to 2012 we incurred debt origination and legal costs of which, as of March 31, 2014, approximately $4.5 million remains to be amortized through the maturity date of the revolving credit facility.

[4] Under the terms of the revolving credit facility, we may exercise an option to extend the maturity date by one year.