Consolidated Balance Sheets (KILROY REALTY, L.P.) (Parenthetical) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity Consolidated Carrying Amounts, Real Estate Assets, net	$ 187,254,000	$ 211,755,000
Kilroy Realty, L.P. [Member] | Capital units [Member]
General Partners' Capital Account, Units Issued	98,620,333	93,219,439
General Partners' Capital Account, Units Outstanding	98,620,333	93,219,439
Limited Partners' Capital Account, Units Issued	2,077,193	2,381,543
Noncontrolling common units of the Operating Partnership	2,077,193	2,381,543
Kilroy Realty, L.P. [Member] | Series G Cumulative Redeemable Preferred Unit [Member]
Preferred units, issued	0	4,000,000
Preferred units outstanding	0	4,000,000
Preferred stock dividend rate (percentage)	0.00%	6.875%
Preferred stock liquidation preference	$ 0	$ 100,000,000
Kilroy Realty, L.P. [Member] | Series H Cumulative Redeemable Preferred Unit [Member]
Preferred units, issued	0	4,000,000
Preferred units outstanding	0	4,000,000
Preferred stock dividend rate (percentage)	0.00%	6.375%
Preferred stock liquidation preference	$ 0	$ 100,000,000