Organization and Basis of Presentation (Details Textuals) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Lease-Up Properties, Maximum Stabilized Occupacy, Percentage	95.00%
Percentage of general partnership interest owned by the company in the Operating Partnership	97.90%	97.80%	97.60%
Percentage of Common limited partnership interest owned by certain non-affiliated investors and certain directors and officers of the Company in the Operating Partnership	2.10%	2.20%	2.40%
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 61,600,000	$ 251,800,000
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	6,800,000	12,100,000
Noncontrolling Interest in Variable Interest Entity	4,885,000	4,885,000
WASHINGTON
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of buildings	13
Kilroy Realty Finance, Inc. [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	1.00%
Kilroy Realty, L.P. [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of limited partnership interest owned by Operating Partnership	99.00%
Real Estate Investment [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 60,600,000	$ 234,500,000