Secured and Unsecured Debt of the Operating Partnership Capitalized Interest and Loan Fees (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Capitalized Interest and Loan Fees [Line Items]
Interest Expense	$ 17,252	$ 19,734
Kilroy Realty, L.P. [Member]
Capitalized Interest and Loan Fees [Line Items]
Gross interest expense	28,034	27,466
Capitalized interest	(10,782)	(7,732)
Interest Expense	$ 17,252	$ 19,734