Net (Loss) Income Available to Common Stockholders Per Share of the Company (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 Corporation	$ 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) income available to common stockholders	$ (644)	$ (2,088)	$ 68	$ 2,499
Denominator:
Weighted average common shares outstanding - basic (Note 14)	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
Diluted weighted average vested shares and common share equivalents outstanding	57,685,710	50,296,643	55,384,729	46,677,850
Basic earnings per share:
Net (loss) income available to common stockholders per share-basic	$ (0.01)	$ (0.04)	$ 0.00	$ 0.05
Diluted earnings per share:
Net (loss) income available to common stockholders per share-diluted	$ (0.01)	$ (0.04)	$ 0.00	$ 0.05