Secured and Unsecured Debt of the Operating Partnership - Unsecured Senior Notes - Private Placement (Details) - Kilroy Realty, L.P. [Member] - USD ($)	6 Months Ended
	Jun. 30, 2017	Feb. 17, 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,579,552,000
Unsecured Debt [Member] | Three point three five percent Series A Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross	75,000,000	$ 175,000,000
Stated coupon rate		3.35%
Unsecured Debt [Member] | Three point four five percent Series B Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 175,000,000	$ 75,000,000
Stated coupon rate		3.45%
Unsecured Debt [Member] | Series A and B Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Operating partnership, payment percent	5.00%
Operating partnership, total payment percentage	100.00%