Consolidated Statements of Capital (KILROY REALTY, L.P.) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 178,113	$ 44,002
Noncash amortization of share-based compensation	5,911	4,302
Settlement of restricted stock units	(1)	0
Preferred distributions	(3,313)	(3,313)
Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,805	815
Kilroy Realty, L.P. [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	3,234,586	2,723,936
Net income	178,113	44,002
Issuance of common units		113,097
Issuance of common units in connection with acquisition (Note 2)	48,033
Issuance of share-based compensation awards	404	413
Noncash amortization of share-based compensation	5,911	4,302
Exercise of stock options	256	10,482
Repurchase of common units, stock options and restricted stock units	(5,619)	(1,821)
Settlement of restricted stock units	(1)	0
Preferred distributions	(3,313)	(3,313)
Distributions declared per common unit ($0.35 per unit)	(33,672)	(31,892)
Ending Balance	3,424,698	2,859,206
Kilroy Realty, L.P. [Member] | Partners Capital Preferred Units [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	192,411	192,411
Ending Balance	192,411	192,411
Kilroy Realty, L.P. [Member] | Partners Capital Common Unit [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 3,031,609	$ 2,521,900
Beginning Balance units	94,023,465	88,063,884
Net income	$ 177,833	$ 43,927
Issuance of common units, units		1,507,393
Issuance of common units		$ 113,097
Issuance of common units in connection with acquisition (Note 2), units	867,701
Issuance of common units in connection with acquisition (Note 2)	$ 48,033
Issuance of share-based compensation awards	404	413
Noncash amortization of share-based compensation	$ 5,911	$ 4,302
Exercise of stock options, units	6,000	237,000
Exercise of stock options	$ 256	$ 10,482
Repurchase of common units and restricted stock units, units	(92,089)	(20,429)
Repurchase of common units, stock options and restricted stock units	$ (5,619)	$ (1,821)
Settlement of restricted stock units, units	55,663	36,699
Settlement of restricted stock units	$ (1)	$ 0
Preferred distributions	(3,313)	(3,313)
Distributions declared per common unit ($0.35 per unit)	(33,672)	(31,892)
Ending Balance	$ 3,221,441	$ 2,657,095
Ending Balance units	94,860,740	89,824,547
Kilroy Realty, L.P. [Member] | Total Partners Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 3,224,020	$ 2,714,311
Net income	177,833	43,927
Issuance of common units		113,097
Issuance of common units in connection with acquisition (Note 2)	48,033
Issuance of share-based compensation awards	404	413
Noncash amortization of share-based compensation	5,911	4,302
Exercise of stock options	256	10,482
Repurchase of common units, stock options and restricted stock units	(5,619)	(1,821)
Settlement of restricted stock units	(1)	0
Preferred distributions	(3,313)	(3,313)
Distributions declared per common unit ($0.35 per unit)	(33,672)	(31,892)
Ending Balance	3,413,852	2,849,506
Kilroy Realty, L.P. [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	10,566	9,625
Net income	280	75
Ending Balance	$ 10,846	$ 9,700