Net (Loss) 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, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Numerator:
Income (loss) from continuing operations	$ 2,683		$ (2,167)		$ 10,289		$ (4,941)
Loss (income) from continuing operations attributable to noncontrolling common units of the Operating Partnership	14		179		(8)		564
Preferred distributions and dividends	(3,312)		(5,342)		(9,938)		(17,775)
Allocation to participating securities	(450)	[1]	(408)	[1]	(1,292)	[1]	(1,225)	[1]
Numerator for basic and diluted loss from continuing operations available to common stockholders	(1,065)		(7,738)		(949)		(23,377)
Income from discontinued operations	6,344		4,689		11,229		88,412
Income from discontinued operations attributable to noncontrolling common units of the Operating Partnership	(145)		(112)		(258)		(2,272)
Numerator for basic and diluted net income (loss) available to common stockholders	5,134		(3,161)		10,022		62,763
Denominator:
Weighted average common shares outstanding - basic (Note 13)	76,768,893		71,889,475		75,750,822		67,975,309
Effect of dilutive securities - contingently issuable shares and stock options	0		0		0		0
Weighted average common shares outstanding-diluted	76,768,893		71,889,475		75,750,822		67,975,309
Basic earnings per share:
Loss from continuing operations available to common unitholders per common unit-basic (Note 14)	$ (0.01)		$ (0.10)		$ (0.01)		$ (0.34)
Income from discontinued operations per common share	$ 0.08		$ 0.06		$ 0.14		$ 1.26
Net (loss) income available to common stockholders per share-basic	$ 0.07		$ (0.04)		$ 0.13		$ 0.92
Diluted earnings per share:
Loss from continuing operations available to common unitholders per common unit-diluted (Note 14)	$ (0.01)		$ (0.10)		$ (0.01)		$ (0.34)
Income from discontinued operations per common share	$ 0.08		$ 0.06		$ 0.14		$ 1.26
Net (loss) income available to common stockholders per share-diluted	$ 0.07		$ (0.04)		$ 0.13		$ 0.92
Stock options outstanding	1,525,000		1,540,000		1,525,000		1,540,000
Kilroy Realty, L.P. [Member]
Numerator:
Income (loss) from continuing operations	2,683		(2,167)		10,289		(4,941)
Preferred distributions and dividends	(3,312)		(5,342)		(9,938)		(17,775)
Allocation to participating securities	450	[1]	408	[1]	1,292	[1]	1,225	[1]
Numerator for basic and diluted loss from continuing operations available to common stockholders	(1,126)		(7,965)		(1,119)		(24,085)
Income from discontinued operations	6,344		4,689		11,229		88,412
Numerator for basic and diluted net income (loss) available to common stockholders	$ 5,218		$ (3,276)		$ 10,110		$ 64,327
Denominator:
Weighted average common shares outstanding - basic (Note 13)	78,590,396		73,680,259		77,574,907		69,717,834
Effect of dilutive securities - contingently issuable shares and stock options	0		0		0		0
Weighted average common shares outstanding-diluted	78,590,396		73,680,259		77,574,907		69,717,834
Basic earnings per share:
Loss from continuing operations available to common unitholders per common unit-basic (Note 14)	$ (0.01)		$ (0.10)		$ (0.01)		$ (0.34)
Income from discontinued operations per common share	$ 0.08		$ 0.06		$ 0.14		$ 1.26
Net (loss) income available to common stockholders per share-basic	$ 0.07		$ (0.04)		$ 0.13		$ 0.92
Diluted earnings per share:
Loss from continuing operations available to common unitholders per common unit-diluted (Note 14)	$ (0.01)		$ (0.10)		$ (0.01)		$ (0.34)
Income from discontinued operations per common share	$ 0.08		$ 0.06		$ 0.14		$ 1.26
Net (loss) income available to common stockholders per share-diluted	$ 0.07		$ (0.04)		$ 0.13		$ 0.92

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