Net Income Available to Common Stockholders Per Share of the Company (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net income attributable to Kilroy Realty Corporation	$ 42,194	$ 27,549	$ 79,097	$ 63,795
Allocation to participating securities	(543)	(514)	(1,052)	(985)
Numerator for basic and diluted net income available to common stockholders	$ 41,651	$ 27,035	$ 78,045	$ 62,810
Denominator:
Basic weighted average vested shares outstanding (in shares)	100,972,355	99,691,700	100,937,069	99,220,577
Effect of dilutive securities (in shares)	837,186	459,156	681,884	467,105
Diluted weighted average vested shares and common share equivalents outstanding (in shares)	101,809,541	100,150,856	101,618,953	99,687,682
Basic earnings per share:
Net income available to common stockholders per share (in dollars per share)	$ 0.41	$ 0.27	$ 0.77	$ 0.63
Diluted earnings per share:
Net income available to common stockholders per share (in dollars per share)	$ 0.41	$ 0.27	$ 0.77	$ 0.63