Consolidated Statements of Capital (KILROY REALTY, L.P.) (Kilroy Realty, L.P. [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended									12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Total Partners Capital [Member]	Dec. 31, 2011 Total Partners Capital [Member]	Dec. 31, 2010 Total Partners Capital [Member]	Dec. 31, 2012 Partners Capital Preferred Units [Member]	Dec. 31, 2010 Partners Capital Preferred Units [Member]	Dec. 31, 2009 Partners Capital Preferred Units [Member]	Dec. 31, 2012 Partners Capital Common Unit [Member]	Dec. 31, 2011 Partners Capital Common Unit [Member]	Dec. 31, 2010 Partners Capital Common Unit [Member]	Dec. 31, 2012 Noncontrolling Interest In Consolidated Subsidiaries [Member]	Dec. 31, 2011 Noncontrolling Interest In Consolidated Subsidiaries [Member]	Dec. 31, 2010 Noncontrolling Interest In Consolidated Subsidiaries [Member]	Dec. 31, 2012 Series E and Series F Cumulative Redeemable Preferred Stock [Member]	Dec. 31, 2012 Series E and Series F Cumulative Redeemable Preferred Stock [Member] Total Partners Capital [Member]	Dec. 31, 2012 Series E and Series F Cumulative Redeemable Preferred Stock [Member] Partners Capital Common Unit [Member]	Dec. 31, 2012 Series A Preferred Units [Member]	Dec. 31, 2012 Series A Preferred Units [Member] Total Partners Capital [Member]	Dec. 31, 2012 Series A Preferred Units [Member] Partners Capital Common Unit [Member]
Distributions Per Common Unit	$ 1.4	$ 1.4	$ 1.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,327,482	$ 1,117,730	$ 883,838	$ 1,324,841	$ 1,116,093	$ 882,338	$ 121,582	$ 121,582	$ 121,582	$ 1,203,259	$ 994,511	$ 760,756	$ 2,641	$ 1,637	$ 1,500
Beginning Balance units										60,537,848	54,072,801	44,871,893
Net income	277,101	67,489	19,886	276,463	66,960	19,724				276,463	66,960	19,724	638	529	162
Proceeds from issuance of preferred stock	192,411			192,411			192,411
Redemption of Series E and Series F Preferred units (Note 11), shares							121,582
Original issuance costs of redeemed preferred units (Notes 9 and 11)	(6,980)	0	0													(126,500)	(126,500)	(4,918)	(2,062)	(2,062)	(2,062)
Issuance of common units (Note 11)	672,102	233,312	299,847	672,102	233,312	299,847				672,102	233,312	299,847
Issuance of common units in connection with an operating property acquisition ( Notes 2 and 11)										118,372
Issuance of common units in the Operating Partnership in connection with an operating property acquisition (Note 3)	5,604	0	0	5,604						5,604
Issuance of common units, units (Note 11)										16,024,618	6,392,805
Issuance of share-based compensation awards (Note 12)	1,291	2,739	2,151	1,291	2,739	2,151				1,291	2,739	2,151
Issuance of share-based compensation awards, units (Note 12)										62,137	68,727	3,239
Noncash amortization of share-based compensation	8,537	5,588	6,687	8,537	5,588	6,687				8,537	5,588	6,687
Repurchase of common units and restricted stock units (Note 12)	(877)	(1,152)	(2,121)	(877)	(1,152)	(2,121)				(877)	(1,152)	(2,121)
Repurchase of common units and restricted stock units, units (Note 12)										(22,312)	(11,485)	(59,782)
Allocation to the equity component of cash paid upon repurchase of 3.25% Exchangeable Notes (Note 7)			(2,694)			(2,694)						(2,694)
Other		0	0		(475)	25					(475)	25		475	(25)
Preferred Stock Dividends, Income Statement Impact	14,108	15,196	15,196	14,108						14,108	15,196
Preferred dividends and distributions	(21,088)	(15,196)	(15,196)		(15,196)	(15,196)						(15,196)
Distributions declared per common unit ($1.40 per unit)	(104,393)	(83,423)	(73,455)	(104,393)	(83,423)	(73,455)				(104,393)	(83,423)	(73,455)
Settlement of restricted stock units for shares of common stock	(784)		(1,296)	(784)		(1,296)				(784)		(1,296)
Settlement of restricted stock units for shares of common stock units										27,821		53,451
Exercise of stock options	129	395	83	129	395	83				129	395	83
Exercise of stock options, units										5,000	15,000	4,000
Ending Balance	$ 2,235,933	$ 1,327,482	$ 1,117,730	$ 2,232,654	$ 1,324,841	$ 1,116,093	$ 192,411	$ 121,582	$ 121,582	$ 2,040,243	$ 1,203,259	$ 994,511	$ 3,279	$ 2,641	$ 1,637
Ending Balance units										76,753,484	60,537,848	54,072,801