v3.3.1.900

Secured and Unsecured Debt of the Operating Partnership - Exchangeable Senior Notes (Details) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Nov. 30, 2014 | Nov. 30, 2009 | Dec. 31, 2015 shares | Dec. 31, 2014 $ / shares shares | Dec. 31, 2015 USD ($) shares | Dec. 31, 2014 USD ($) $ / shares shares | Dec. 31, 2013 USD ($) $ / shares | Jun. 30, 2015 USD ($) | Nov. 13, 2014 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Average Trading Price Of The Companys Stock | $ / shares |  |  |  |  |  | $ 60.04 | [1] | $ 52.12 |  |
Debt Instrument, Unamortized Premium |  |  |  |  |  |  |  |  | $ 6,200 |
Capped call transactions |  |  |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Conversion Ratio |  |  |  |  |  | 27.8307 |  |  |  |
Conversion of Stock, Shares Converted | shares |  |  |  |  |  | 4,800,796 |  |  |  |
Interest expense |  |  |  |  | $ 57,682 | $ 67,571 |  | $ 75,870 |  |
Exchangeable Notes [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Debt Instrument, Issuance Date |  | Nov. 01, 2009 |  |  |  |  |  |  |  |
Balance and significant terms of the Exchangeable Notes outstanding |  |  |  |  |  |  |  |  |  |
Maturity date | Nov. 01, 2014 |  |  |  |  |  |  |  |  |
Stated interest rate |  |  |  | 4.00% |  | 4.00% |  |  |  |
Effective interest rate |  |  |  | 7.00% |  | 7.00% |  |  |  |
Capped call transactions |  |  |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Conversion Price | $ / shares |  |  |  | $ 35.93 |  | $ 35.93 |  |  |  |
Kilroy Realty, L.P. [Member] |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Interest Costs Incurred |  |  |  |  | 109,647 | $ 114,661 |  | 111,238 |  |
Interest Costs Capitalized Adjustment |  |  |  |  | (51,965) | (47,090) |  | (35,368) |  |
Capped call transactions |  |  |  |  |  |  |  |  |  |
Interest expense |  |  |  |  | $ 57,682 | $ 67,571 |  | $ 75,870 |  |
Kilroy Realty, L.P. [Member] | Exchangeable Notes [Member] |  |  |  |  |  |  |  |  |  |
Balance and significant terms of the Exchangeable Notes outstanding |  |  |  |  |  |  |  |  |  |
Long-term Debt, Gross |  |  |  |  |  |  |  |  |  | $ 135,500
Common Stock |  |  |  |  |  |  |  |  |  |
Debt Disclosure [Abstract] |  |  |  |  |  |  |  |  |  |
Stock issued during period, shares, conversion of convertible securities, net of adjustments | shares |  |  |  |  | 1,255,917 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Conversion of Convertible Securities | shares |  |  | 1,660,053 | 431,270 |  |  |  |  |  |
Common Stock, Issued, Net of Capped Calls | shares |  |  |  | 320,064 | 1,575,981 |  |  |  |  |
[1] | Period Ended November 15, 2014(1) Year Ended December 31, 2013Per share average trading price of the Company's common stock$60.04 $52.12_______________(1) Represents the maturity date of the 4.25% Exchangeable Notes.

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