Net Income Available to Common Stockholders Per Share of the Company (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Numerator:
Income from continuing operations	$ 13,168		$ 3,179		$ 39,896		$ 9,896
(Income) Loss from continuing operations attributable to noncontrolling common units of the Operating Partnership	(193)		3		(635)		2
Preferred dividends	(3,313)		(3,312)		(9,938)		(9,938)
Allocation to participating securities	(432)	[1]	(450)	[1]	(1,285)	[1]	(1,292)	[1]
Numerator for basic and diluted income from continuing operations available to common stockholders	9,230		(580)		28,038		(1,332)
Income from discontinued operations	6,135		5,848		112,482		11,622
Income from discontinued operations attributable to noncontrolling common units of the Operating Partnership	(128)		(134)		(2,376)		(268)
Numerator for basic and diluted net income available to common stockholders	15,237		5,134		138,144		10,022
Denominator:
Weighted average common shares outstanding – basic (Note 14)	83,161,323		76,768,893		82,525,033		75,750,822
Effect of dilutive securities	1,949,133		0		2,097,589		0
Weighted average common shares outstanding-diluted	85,110,456		76,768,893		84,622,622		75,750,822
Basic earnings per share:
Income (loss) from continuing operations available to common stockholders per common share – basic (Note 14)	$ 0.11		$ 0.00		$ 0.34		$ (0.02)
Income from discontinued operations per common share	$ 0.07		$ 0.07		$ 1.33		$ 0.15
Net income available to common stockholders per share-basic	$ 0.18		$ 0.07		$ 1.67		$ 0.13
Diluted earnings per share:
Income (loss) from continuing operations available to common stockholders per common share – diluted (Note 14)	$ 0.11		$ 0.00		$ 0.33		$ (0.02)
Income from discontinued operations per common share	$ 0.07		$ 0.07		$ 1.30		$ 0.15
Net income available to common stockholders per share-diluted	$ 0.18		$ 0.07		$ 1.63		$ 0.13
Kilroy Realty, L.P. [Member]
Numerator:
Income from continuing operations	13,168		3,179		39,896		9,896
Preferred dividends	(3,313)		(3,312)		(9,938)		(9,938)
Allocation to participating securities	(432)	[1]	(450)	[1]	(1,285)	[1]	(1,292)	[1]
Numerator for basic and diluted income from continuing operations available to common stockholders	9,364		(630)		28,472		(1,512)
Income from discontinued operations	6,135		5,848		112,482		11,622
Numerator for basic and diluted net income available to common stockholders	$ 15,499		$ 5,218		$ 140,954		$ 10,110
Denominator:
Weighted average common shares outstanding – basic (Note 14)	84,965,523		78,590,396		84,329,317		77,574,907
Effect of dilutive securities	1,949,133		0		2,097,589		0
Weighted average common shares outstanding-diluted	86,914,656		78,590,396		86,426,906		77,574,907
Basic earnings per share:
Income (loss) from continuing operations available to common stockholders per common share – basic (Note 14)	$ 0.11		$ 0.00		$ 0.34		$ (0.02)
Income from discontinued operations per common share	$ 0.07		$ 0.07		$ 1.33		$ 0.15
Net income available to common stockholders per share-basic	$ 0.18		$ 0.07		$ 1.67		$ 0.13
Diluted earnings per share:
Income (loss) from continuing operations available to common stockholders per common share – diluted (Note 14)	$ 0.11		$ 0.00		$ 0.33		$ (0.02)
Income from discontinued operations per common share	$ 0.07		$ 0.07		$ 1.30		$ 0.15
Net income available to common stockholders per share-diluted	$ 0.18		$ 0.07		$ 1.63		$ 0.13

[1] Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs.