Consolidated Balance Sheets (KILROY REALTY, L.P.) (Parenthetical) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Carrying amounts of consolidated VIE	$ 180,488,000	$ 211,755,000
Common units held by limited partners	1,788,170	1,804,200
Common stock, par value	$ 0.01
Kilroy Realty, L.P. [Member]
Carrying amounts of consolidated VIE	$ 180,488,000	$ 211,755,000
Kilroy Realty, L.P. [Member] | Common Units [Member]
General partner, units issued	88,405,632	86,259,684
General partners, units outstanding	88,405,632	86,259,684
Limited partners, units issued	1,793,170	1,804,200
Common units held by limited partners	1,793,170	1,804,200
Kilroy Realty, L.P. [Member] | Series G Cumulative Redeemable Preferred Unit [Member]
Preferred Units, Issued	4,000,000	4,000,000
Preferred Units, Outstanding	4,000,000	4,000,000
Preferred stock dividend rate percentage	6.875%	6.875%
Preferred Stock Liquidation preference	$ 100,000,000	$ 100,000,000
Kilroy Realty, L.P. [Member] | Series H Cumulative Redeemable Preferred Unit [Member]
Preferred Units, Issued	4,000,000	4,000,000
Preferred Units, Outstanding	4,000,000	4,000,000
Preferred stock dividend rate percentage	6.375%	6.375%
Preferred Stock Liquidation preference	$ 100,000,000	$ 100,000,000