Supplemental Cash Flow Information of the Operating Partnership (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of capitalized interest of $13,815 and $10,669 as of March 31, 2016 and 2015, respectively	$ 13,797	$ 19,814
Noncash Investing Activities [Abstract]
Accrual for expenditures for operating properties and development properties	59,218	85,656
Tenant improvements funded directly by tenants	10,664	231
Assumption of accrued liabilities in connection with development acquisitions (Note 2)	4,741	1,478
Release of holdback funds to third party	0	8,279
Noncash Financing Activities [Abstract]
Issuance of common units in connection with an acquisition (Note 2)	48,033	0
Accrual of dividends and distributions payable to common unitholders	33,677	31,892
Accrual of dividends and distributions payable to preferred unitholders	1,656	1,656
Interest capitalized	13,815	10,669
Kilroy Realty, L.P. [Member]
Supplemental Cash Flow Information [Abstract]
Cash paid for interest, net of capitalized interest of $13,815 and $10,669 as of March 31, 2016 and 2015, respectively	13,797	19,814
Noncash Investing Activities [Abstract]
Accrual for expenditures for operating properties and development properties	59,218	85,656
Tenant improvements funded directly by tenants	10,664	231
Assumption of accrued liabilities in connection with development acquisitions (Note 2)	4,741	1,478
Release of holdback funds to third party	0	8,279
Noncash Financing Activities [Abstract]
Issuance of common units in connection with an acquisition (Note 2)	48,033	0
Accrual of dividends and distributions payable to common unitholders	33,677	31,892
Accrual of dividends and distributions payable to preferred unitholders	1,656	1,656
Interest capitalized	$ 13,815	$ 10,669