Share-Based Compensation (Details Textuals) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Jan. 27, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				212,468
Share Price	$ 75.34
Share-based Compensation Capitalized		$ 0.7	$ 0.6	$ 2.3	$ 1.5
Share-based Compensation, Unrecognized costs		35.2		$ 35.2
Share-based Compensation, Unrecognized costs, weighted-average vesting period				2 years 1 month
Allocated Share-based Compensation Expense		$ 4.3	$ 4.0	$ 13.6	$ 10.3
Market Measure-Based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 78.55
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate				20.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate				0.92%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				127,657
Share-based Compensation Arrangement by Share-based Payment Award, Options, Other Increases (Decreases) in Period		168,788		168,788
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	2 years 11 months
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Grants In Period, Grant Date Fair Value				$ 10.1
Time-Based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period				84,811
Share-based Compensation Arrangement By Share-based Payment Award, Equity Instruments Other Than Options, Grants In Period, Grant Date Fair Value				$ 6.4
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price				$ 42.61
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term		687,000		687,000
Kilroy Realty 2006 Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		1,724,324		1,724,324
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Paid for Tax Withholding for Share Based Compensation				39,317	48,017
Exercise of stock options				(265,000)	(482,000)
Shareholder Meeting Date May 21, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Requested		8,320,000		8,320,000

Kilroy Realty, L.P. 10-Q