Net Income Available to Common Unitholders Per Unit of the Operating Partnership (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Numerator:
Income from continuing operations	$ 4,962		$ 1,844
Total preferred distributions	(9,336)		(3,799)
Allocation to participating securities (nonvested units and time-based RSUs)	(380)		(322)
Numerator for basic and diluted (loss) income from continuing operations available to common unitholders	(4,640)		(2,216)
Income from discontinued operations	73,709	[1]	3,023	[1],[2]
Numerator for basic and diluted net income available to common unitholders	67,160		712
Denominator:
Weighted average common units outstanding - basic (Note 16)	63,648,704		52,302,075
Effect of dilutive securities - contingently issuable shares and stock options	0		0	[3]
Weighted average common units outstanding - diluted (Note 16)	63,648,704		52,302,075
Basic earnings per unit:
Loss from continuing operations available to common unitholders per common unit-basic (Note 16)	$ (0.07)		$ (0.04)
Income from discontinued operations per common unit	$ 1.13		$ 0.05
Net income available to common unitholders per unit-basic (Note 16)	$ 1.06		$ 0.01
Diluted earnings per unit:
Loss from continuing operations available to common unitholders per common unit-diluted (Note 16)	$ (0.07)		$ (0.04)
Income from discontinued operations per common unit	$ 1.13		$ 0.05
Net income available to common unitholders per unit-diluted (Note 16)	$ 1.06		$ 0.01
Stock options outstanding	1,550,000	[4],[5]			5,000	[6]
Kilroy Realty, L.P. [Member]
Numerator:
Income from continuing operations	4,962		1,844
Income from continuing operations attributable to noncontrolling interests in consolidated subsidiaries	(53)		(34)
Total preferred distributions	(9,336)		(3,799)
Allocation to participating securities (nonvested units and time-based RSUs)	(380)		(322)
Numerator for basic and diluted (loss) income from continuing operations available to common unitholders	(4,807)		(2,311)
Income from discontinued operations	73,709		3,023
Numerator for basic and diluted net income available to common unitholders	$ 68,902		$ 712
Denominator:
Weighted average common units outstanding - basic (Note 16)	65,366,835		54,025,206
Effect of dilutive securities - contingently issuable shares and stock options	0		0	[7]
Weighted average common units outstanding - diluted (Note 16)	65,366,835		54,025,206
Basic earnings per unit:
Loss from continuing operations available to common unitholders per common unit-basic (Note 16)	$ (0.07)		$ (0.04)
Income from discontinued operations per common unit	$ 1.12		$ 0.05
Net income available to common unitholders per unit-basic (Note 16)	$ 1.05		$ 0.01
Diluted earnings per unit:
Loss from continuing operations available to common unitholders per common unit-diluted (Note 16)	$ (0.07)		$ (0.04)
Income from discontinued operations per common unit	$ 1.12		$ 0.05
Net income available to common unitholders per unit-diluted (Note 16)	$ 1.05		$ 0.01
Stock options outstanding	1,550,000	[4]
Market Measure-Based Restricted Stock Units (RSUs) [Member]
Diluted earnings per unit:
Market measure-based RSUs	103,238
Market Measure-Based Restricted Stock Units (RSUs) [Member] | Kilroy Realty, L.P. [Member]
Diluted earnings per unit:
Market measure-based RSUs	103,238

[1] See Note 14 for the breakdown of income from discontinued operations by segment.

[2] Includes two office and one industrial buildings encompassing 282,611 rentable square feet that were disposed of in 2011.

[3] Dilutive securities were not included in the current period presentation of the 2011 weighted average shares outstanding because we reported a net loss from continuing operations attributable to common stockholders for the three months ended March 31, 2011 resulting from the reclassification of the revenues and expenses of operating properties that were sold during 2011 and 2012.

[4] The total intrinsic value of options outstanding at March 31, 2012 was $6.2 million.

[5] As of March 31, 2012, none of the outstanding stock options were exercisable.

[6] Stock options outstanding as of December 31, 2011 were granted in 2002 and exercised in 2012 prior to expiration. No stock options were granted during 2003 through 2011.

[7] Dilutive securities were not included in the current period presentation of the 2011 weighted average units outstanding because the Operating Partnership reported a net loss from continuing operations attributable to common unitholders for the three months ended March 31, 2011 resulting from the reclassification of the revenues and expenses of operating properties that were sold during 2011 and 2012.