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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net income attributable to Kilroy Realty Corporation	$ 31,448	$ 32,847	$ 64,973	$ 207,155
Total preferred dividends	(1,615)	(3,312)	(8,811)	(6,625)
Allocation to participating securities (1)	(511)	(423)	(959)	(818)
Numerator for basic and diluted net income available to common stockholders	$ 29,322	$ 29,112	$ 55,203	$ 199,712
Denominator:
Weighted average common shares outstanding – basic (in shares)	98,275,471	92,209,955	97,834,255	92,217,238
Effect of dilutive securities (in shares)	551,907	614,831	593,090	566,827
Diluted weighted average vested shares and common share equivalents outstanding (in shares)	98,827,378	92,824,786	98,427,345	92,784,065
Basic earnings per share:
Net income available to common stockholders per share (in dollars per share)	$ 0.30	$ 0.32	$ 0.56	$ 2.17
Diluted earnings per share:
Net income available to common stockholders per share (in dollars per share)	$ 0.30	$ 0.31	$ 0.56	$ 2.15