Net Income Available to Common Stockholders Per Share of the Company (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Numerator:
Net income attributable to Kilroy Realty Corporation		$ 174,308	$ 43,187
Preferred dividends		(3,313)	(3,313)
Allocation to participating securities	[1]	(395)	(415)
Numerator for basic and diluted net income available to common stockholders		$ 170,600	$ 39,459
Denominator:
Basic weighted average vested shares outstanding		92,224,522	86,896,776
Effect of dilutive securities		510,021	537,590
Diluted weighted average vested shares and common share equivalents outstanding		92,734,543	87,434,366
Basic earnings per share:
Net income available to common stockholders per share (in dollars per share)		$ 1.85	$ 0.45
Diluted earnings per share:
Net income available to common stockholders per share (in dollars per share)		$ 1.84	$ 0.45

[1] Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs.