Net Income Available to Common Unitholders Per Unit of the Operating Partnership (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income attributable to Kilroy Realty, L.P.	$ 39,817	$ 36,903
Allocation to participating securities	(543)	(509)
Numerator for basic and diluted net income available to common stockholders	$ 39,274	$ 36,394
Denominator:
Basic weighted average vested shares outstanding (in shares)	106,875,234	100,901,390
Effect of dilutive securities (in units)	514,341	541,789
Diluted weighted average vested shares and common stock equivalents outstanding (in shares)	107,389,575	101,443,179
Basic earnings per unit:
Net income available to common stockholders per share (in dollars per share)	$ 0.37	$ 0.36
Diluted earnings per unit:
Net income available to common stockholders per share (in dollars per share)	$ 0.37	$ 0.36
Kilroy Realty L.P. [Member]
Numerator:
Net income attributable to Kilroy Realty, L.P.	$ 40,389	$ 37,508
Allocation to participating securities	(543)	(509)
Numerator for basic and diluted net income available to common stockholders	$ 39,846	$ 36,999
Denominator:
Basic weighted average vested shares outstanding (in shares)	108,897,027	102,925,166
Effect of dilutive securities (in units)	514,341	541,789
Diluted weighted average vested shares and common stock equivalents outstanding (in shares)	109,411,368	103,466,955
Basic earnings per unit:
Net income available to common stockholders per share (in dollars per share)	$ 0.37	$ 0.36
Diluted earnings per unit:
Net income available to common stockholders per share (in dollars per share)	$ 0.36	$ 0.36