Other Ownership Interests, Contributed Capital, Working Capital Contribution

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Other Ownership Interests, Mortgage Debt

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Area of a real estate property.

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Number of shares of equity interests issued or issuable to acquire entity.

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Face amount or stated value per share of common stock.

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Amount of increase reasonably possible in the next twelve months for the unrecognized tax benefit.

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- Definition

The number of limited partner units outstanding.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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Portion of equity (net assets) in a variable interest entity (VIE) not attributable, directly or indirectly, to the parent entity. That is, this is the portion of equity in a VIE that is attributable to the noncontrolling interest (previously referred to as minority interest).

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Amount of increase in noncontrolling interest from sale of a portion of the parent's controlling interest.

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The number of real estate properties owned as of the balance sheet date.

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Carrying amount of equity interests owned by noncontrolling shareholders, partners, or other equity holders in one or more of the entities consolidated into the reporting entity's financial statements other than joint ventures, limited partnerships, operating partnerships or interests held by preferred unit holders.

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The amount of capital contributed by other unit holders.

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The book value of investments in real estate joint ventures including direct and indirect investments.

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The fair value as of the reporting date of noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. The noncontrolling interest holder's ownership (or holders' ownership) may be in the form of common shares (regardless of class), limited partnership units (regardless of class), non-preferential membership interests, or any other form of common equity regardless of investee entity legal form.

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Noncontrolling Interests on the Company's Consolidated Financial Statements (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2016 $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Nov. 30, 2016 USD ($)	Aug. 30, 2016 USD ($) ft² property	Dec. 31, 2015 USD ($) shares
Noncontrolling Interest [Line Items]
Percentage of general partnership interest owned by the company in the Operating Partnership		97.50%			98.10%
Ownership interest of noncontrolling interest		2.50%			1.90%
Noncontrolling common units \| shares		2,381,543			1,764,775
Aggregate value upon redemption of outstanding noncontrolling common units		$ 174,900,000			$ 112,000,000
Noncontrolling interest, increase from sale of parent equity interest		453,449,000
Noncontrolling interest in consolidated subsidiary		130,732,000			6,520,000
Kilroy Realty, L.P. [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest, increase from sale of parent equity interest		453,449,000
100 First LLC & 303 Second LLC [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest in consolidated subsidiary		$ 124,300,000
Redwood LLC [Member]
Noncontrolling Interest [Line Items]
Percentage of general partnership interest owned by the company in the Operating Partnership		93.00%
Other noncontrolling interests		$ 6,400,000			$ 6,500,000
Capital units [Member] \| Kilroy Realty, L.P. [Member]
Noncontrolling Interest [Line Items]
Noncontrolling common units \| shares		2,381,543			1,764,775
Brannan St Project [Member]
Noncontrolling Interest [Line Items]
Business acquisition, equity interest issued or issuable, number of shares \| shares	867,701
Common stock, par value \| $ / shares	$ 0.01	$ 0.01
Consolidated property partnerships [Member]
Noncontrolling Interest [Line Items]
Real estate investments, joint ventures				$ 1,200,000,000
Consolidated property partnerships [Member] \| Third party [Member]
Noncontrolling Interest [Line Items]
Percentage of general partnership interest owned by the company in the Operating Partnership				44.00%
Ownership interest of noncontrolling interest				44.00%
Number of Buildings \| property				2
Other ownership interests, contributed capital				$ 452,900,000
Other ownership interests, mortgage debt				55,300,000
Other ownership interests, contributed capital, working capital contribution			$ 2,900,000	5,000,000
Consolidated property partnerships, tranche one [Member] \| Third party [Member]
Noncontrolling Interest [Line Items]
Other ownership interests, contributed capital				191,400,000
Other ownership interests, contributed capital, working capital contribution				$ 2,100,000
Additional tax possibly incurred due to transaction		$ 10,900,000.0
Consolidated property partnerships, tranche one [Member] \| 100 First LLC [Member]
Noncontrolling Interest [Line Items]
Area of Real Estate Property \| ft²				467,095
Consolidated property partnerships, tranche two [Member] \| Third party [Member]
Noncontrolling Interest [Line Items]
Other ownership interests, contributed capital			$ 261,500,000
Additional tax possibly incurred due to transaction		18,000,000.0
Consolidated property partnerships, tranche two [Member] \| 303 Second Street [Member]
Noncontrolling Interest [Line Items]
Area of Real Estate Property \| ft²				740,047
Noncontrolling Interest In Consolidated Subsidiaries [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest, increase from sale of parent equity interest		124,452,000
Noncontrolling Interest In Consolidated Subsidiaries [Member] \| Kilroy Realty, L.P. [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest, increase from sale of parent equity interest		(124,452,000)
Common Stock Additional Paid-in Capital [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest, increase from sale of parent equity interest		$ 328,997,000