Net (Loss) Income Available to Common Unitholders Per Unit of the Operating Partnership (Details) (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Numerator:
NET INCOME ATTRIBUTABLE TO KILROY REALTY, L.P.	$ 3,482	$ 2,016	$ 8,315	$ 10,701
Preferred distributions and dividends	(3,799)	(3,799)	(7,598)	(7,598)
NET (LOSS) INCOME AVAILABLE TO COMMON STOCKHOLDERS	(317)	(1,783)	717	3,103
Allocation to participating securities (nonvested units and RSUs)	(327)	(305)	(649)	(604)
Numerator for basic and diluted net (loss) available to common unitholders	(644)	(2,088)	68	2,499
Denominator:
Weighted average common units outstanding - basic (Note 15)	57,685,710	50,296,643	55,008,765	46,674,494
Effect of dilutive securities - Exchangeable Notes and stock options			375,964	3,356
Weighted average common units outstanding - diluted (Note 15)	57,685,710	50,296,643	55,384,729	46,677,850
Basic earnings per unit:
Net (loss) income available to common unitholders per unit-basic	$ (0.01)	$ (0.04)	$ 0.00	$ 0.05
Diluted earnings per unit:
Net (loss) income available to common unitholders per unit-diluted	$ (0.01)	$ (0.04)	$ 0.00	$ 0.05
Operating Partnership [Member]
Numerator:
NET INCOME ATTRIBUTABLE TO KILROY REALTY, L.P.	3,440	1,905	8,274	10,737
Preferred distributions and dividends	(3,799)	(3,799)	(7,598)	(7,598)
NET (LOSS) INCOME AVAILABLE TO COMMON STOCKHOLDERS	(359)	(1,894)	676	3,139
Allocation to participating securities (nonvested units and RSUs)	(327)	(305)	(649)	(604)
Numerator for basic and diluted net (loss) available to common unitholders	$ (686)	$ (2,199)	$ 27	$ 2,535
Denominator:
Weighted average common units outstanding - basic (Note 15)	59,407,687	52,019,774	56,731,316	48,397,625
Effect of dilutive securities - Exchangeable Notes and stock options			375,964	3,356
Weighted average common units outstanding - diluted (Note 15)	59,407,687	52,019,774	57,107,280	48,400,981
Basic earnings per unit:
Net (loss) income available to common unitholders per unit-basic	$ (0.01)	$ (0.04)	$ 0.00	$ 0.05
Diluted earnings per unit:
Net (loss) income available to common unitholders per unit-diluted	$ (0.01)	$ (0.04)	$ 0.00	$ 0.05