v3.3.1.900
Share-Based Compensation (Details Textuals) - USD ($)
$ / shares in Units, $ in Millions
1 Months Ended 3 Months Ended 12 Months Ended
Jan. 27, 2015
Apr. 04, 2013
Feb. 22, 2012
Feb. 28, 2012
Dec. 31, 2012
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)           212,468      
Grant date fair value per share             $ 65.03    
Trading price of the company's stock $ 75.34                
Allocated Share-based Compensation Expense         $ 9.6 $ 18.9 $ 14.5    
Share-based compensation cost capitalized as part of real estate assets         $ 0.9 $ 3.3 $ 2.3    
Total unrecognized compensation cost weighted-average period           1 year 11 months      
Total unrecognized compensation cost related to nonvested incentive awards granted                 $ 31.2
Market Measure-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)           127,657 119,098    
Grants in period, grant date fair value           $ 10.1      
Grant date fair value per share $ 78.55       $ 44.55 [1] $ 79.25 [1],[2]   $ 64.86 [1]  
Expected share price volatility           20.00% 24.00%    
Risk-free interest rate           0.92% 0.61%    
Expected life 2 years 11 months           2 years 7 months    
Time-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)           84,811 117,506    
Grant date fair value per share         $ 49.45 $ 74.49   $ 59.89  
Restricted Stock [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)             213 0  
Grant date fair value per share           $ 0.00 $ 51.35 $ 0.00  
Stock Options [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Expected share price volatility       33.00%          
Risk-free interest rate       1.35%          
Expected life       6 years 6 months          
Kilroy Realty 2006 Incentive Award Plan [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Shares Available for Grant           1,686,608      
Kilroy Realty 2006 Incentive Award Plan [Member] | Stock Options [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Options, Withheld in Period           62,072      
Options, Withheld in Period, Intrinsic Value           $ 3.9      
Minimum [Member] | Executive Officer Share-Based Compensation Programs [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Service Vesting Period           1 year      
Maximum [Member] | Executive Officer Share-Based Compensation Programs [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Service Vesting Period           5 years      
Chief Executive Officer [Member] | Executive Officer Share-Based Compensation Programs [Member] | Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)   236,604              
Chief Executive Officer [Member] | Executive Officer Share-Based Compensation Programs [Member] | Market Measure-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Grants in period, grant date fair value   $ 7.7              
Chief Executive Officer [Member] | Executive Officer Share-Based Compensation Programs [Member] | Time-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Exercise Price   $ 60.16              
Management [Member] | Stock Options [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Award vesting period     5 years            
Options granted in period     1,550,000            
Trading price of the company's stock     $ 42.61            
Expiration period     10 years            
Nonvested Restricted Stock Units R S U [Member] | Market Measure-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)         9,542 191,483   183,365  
Nonvested Restricted Stock Units R S U [Member] | Time-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)         173,758 98,802   155,016  
Number of shares that were tendered to satisfy minimum statutory tax withholding requirements [3]           5,354      
Nonvested Restricted Stock Units R S U [Member] | Restricted Stock [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)           0      
Vested Restricted Stock Units R S U [Member] | Market Measure-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)           0      
Vested Restricted Stock Units R S U [Member] | Time-Based Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Granted (in shares)           0      
Number of shares that were tendered to satisfy minimum statutory tax withholding requirements           20,042      
Vested Restricted Stock Units R S U [Member] | Restricted Stock [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Number of shares that were tendered to satisfy minimum statutory tax withholding requirements           10,699      
Shareholder Meeting Date May 21, 2015 [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Number of Shares Requested           8,320,000      
[1] (1)Represents the grant-date fair value for all awards, excluding the 2014 Performance-Based RSU Grant. As discussed above, the 2014 Performance-Based RSU Grant was re-measured upon stockholder approval of the amended 2006 Plan on May 22, 2014.
[2] Represents the grant-date fair value for all awards, excluding the 2014 Performance-Based RSU Grant. As discussed above, the 2014 Performance-Based RSU Grant was re-measured upon stockholder approval of the amended 2006 Plan on May 22, 2014.
[3] (4)For shares vested but not yet settled, we accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy minimum statutory tax-withholding requirements related to either the settlement or vesting of RSUs in accordance with the terms of the 2006 Plan.