Consolidated Statements of Capital (KILROY REALTY, L.P.) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 35,306	$ 33,892	$ 72,587	$ 212,005
Redemption of Series G preferred units (Note 8)			(100,000)
Original issuance costs of redeemed preferred stock (preferred units)	0	0	(3,845)	0
Non-cash amortization of share-based compensation			12,628	12,538
Settlement of restricted stock units			0	0
Contributions from noncontrolling interests in consolidated property partnerships			250
Distributions to noncontrolling interests in consolidated property partnerships			(8,651)	(281)
Preferred distributions			(4,966)	(6,625)
Noncontrolling Interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income			7,614	4,850
Contributions from noncontrolling interests in consolidated property partnerships			250
Distributions to noncontrolling interests in consolidated property partnerships			(8,651)	(281)
Kilroy Realty, L.P. [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			3,759,317	3,234,586
Net income	35,306	33,892	72,587	212,005
Redemption of Series G preferred units (Note 8)			(100,000)
Original issuance costs of redeemed preferred stock (preferred units)	0	0	(3,845)	0
Issuance of common units			308,832
Issuance of common units in connection with acquisition				48,033
Issuance of share-based compensation awards			4,691	853
Non-cash amortization of share-based compensation			12,628	12,538
Exercise of stock options (Note 9)			12,051	937
Repurchase of common units, stock options and restricted stock units			(11,642)	(5,883)
Settlement of restricted stock units			0	0
Contributions from noncontrolling interests in consolidated property partnerships			250
Distributions to noncontrolling interests in consolidated property partnerships			(8,651)	(281)
Preferred distributions			(4,966)	(6,625)
Distributions declared per common unit ($0.800 and $0.725 per unit for the six months ended June 2017 and 2016, respectively)			(82,626)	(69,529)
Ending balance	3,962,471	3,426,634	3,962,471	3,426,634
Kilroy Realty, L.P. [Member] | Partners Capital Preferred Units [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			192,411	192,411
Redemption of Series G preferred units (Note 8)			(96,155)
Ending balance	96,256	192,411	96,256	192,411
Kilroy Realty, L.P. [Member] | Partners Capital Common Unit [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 3,431,768	$ 3,031,609
Beginning balance (in units)			95,600,982	94,023,465
Net income			$ 66,025	$ 211,423
Original issuance costs of redeemed preferred stock (preferred units)			$ (3,845)
Issuance of common units (in units)			4,427,500
Issuance of common units			$ 308,832
Issuance of common units in connection with acquisition (in units)				867,701
Issuance of common units in connection with acquisition				$ 48,033
Issuance of share-based compensation awards			4,691	853
Non-cash amortization of share-based compensation			$ 12,628	$ 12,538
Exercise of stock options (Note 9) (in units)			272,000	22,000
Exercise of stock options (Note 9)			$ 12,051	$ 937
Repurchase of common units and restricted stock units (in units)			(150,129)	(96,360)
Repurchase of common units, stock options and restricted stock units			$ (11,642)	$ (5,883)
Settlement of restricted stock units (in units)			278,057	69,238
Settlement of restricted stock units			$ 0	$ 0
Contributions from noncontrolling interests in consolidated property partnerships
Preferred distributions			(4,966)	(6,625)
Distributions declared per common unit ($0.800 and $0.725 per unit for the six months ended June 2017 and 2016, respectively)			(82,626)	(69,529)
Ending balance	$ 3,732,916	$ 3,223,356	$ 3,732,916	$ 3,223,356
Ending balance (in units)	100,428,410	94,886,044	100,428,410	94,886,044
Kilroy Realty, L.P. [Member] | Total Partners Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			$ 3,624,179	$ 3,224,020
Net income			66,025	211,423
Redemption of Series G preferred units (Note 8)			(100,000)
Issuance of common units			308,832
Issuance of common units in connection with acquisition				48,033
Issuance of share-based compensation awards			4,691	853
Non-cash amortization of share-based compensation			12,628	12,538
Exercise of stock options (Note 9)			12,051	937
Repurchase of common units, stock options and restricted stock units			(11,642)	(5,883)
Settlement of restricted stock units			0	0
Preferred distributions			(4,966)	(6,625)
Distributions declared per common unit ($0.800 and $0.725 per unit for the six months ended June 2017 and 2016, respectively)			(82,626)	(69,529)
Ending balance	$ 3,829,172	$ 3,415,767	3,829,172	3,415,767
Kilroy Realty, L.P. [Member] | Noncontrolling Interests [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance			135,138	10,566
Net income			6,562	582
Contributions from noncontrolling interests in consolidated property partnerships			250
Distributions to noncontrolling interests in consolidated property partnerships			(8,651)	(281)
Ending balance	$ 133,299	$ 10,867	$ 133,299	$ 10,867