Secured and Unsecured Debt of the Operating Partnership - Capitalized Interest and Loan Fees (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Capitalized Interest and Loan Fees [Line Items]
Interest expense	$ 14,444	$ 11,243
Kilroy Realty L.P. [Member]
Capitalized Interest and Loan Fees [Line Items]
Gross interest expense	35,862	30,680
Capitalized interest and deferred financing costs	(21,418)	(19,437)
Interest expense	$ 14,444	$ 11,243