Consolidated Balance Sheets (KILROY REALTY, L.P.) (Parenthetical) - Common units [Member] - Kilroy Realty L.P. [Member] - shares	Sep. 30, 2018	Dec. 31, 2017
General partner, units issued	100,746,988	98,620,333
General partners, units outstanding	100,746,988	98,620,333
Limited partners, units issued	2,025,287	2,077,193
Noncontrolling common units of the Operating Partnership	2,025,287	2,077,193