Net Income Available to Common Stockholders Per Share of the Company (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income attributable to Kilroy Realty Corporation	$ 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 shares)	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 share:
Net income available to common stockholders per share (in dollars per share)	$ 0.37	$ 0.36
Diluted earnings per share:
Net income available to common stockholders per share (in dollars per share)	$ 0.37	$ 0.36