Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
REVENUES:
Rental income	$ 369,516	$ 307,118	$ 235,304
Tenant reimbursements	32,309	23,977	17,996
Other property income	3,087	6,534	1,694
Total revenues	404,912	337,629	254,994
EXPENSES:
Property expenses	79,357	66,821	51,169
Real estate taxes	34,479	29,633	23,474
Provision for bad debts	153	781	65
Ground leases (Note 4 and 15)	3,168	1,779	984
General and administrative expenses	36,188	28,148	27,963
Acquisition-related expenses	4,937	4,053	2,248
Depreciation and amortization (Notes 2 and 4)	162,917	124,928	90,836
Total expenses	321,199	256,143	196,739
OTHER (EXPENSES) INCOME:
Interest income and other net investment gains (Note 16)	848	571	964
Interest expense (Note 7)	(79,114)	(85,785)	(55,082)
Loss on early extinguishment of debt (Note 7)	0	0	(4,564)
Total other (expenses) income	(78,266)	(85,214)	(58,682)
INCOME (LOSS) FROM CONTINUING OPERATIONS	5,447	(3,728)	(427)
DISCONTINUED OPERATIONS (Note 17)
Income from discontinued operations	12,409	19,630	19,364
Net gain on dispositions of discontinued operations	259,245	51,587	949
Total income from discontinued operations	271,654	71,217	20,313
NET INCOME	277,101	67,489	19,886
Net income attributable to noncontrolling common units of the Operating Partnership	(6,187)	(1,474)	(178)
NET INCOME ATTRIBUTABLE TO KILROY REALTY CORPORATION	270,914	66,015	19,708
PREFERRED DISTRIBUTIONS AND DIVIDENDS:
Distributions to noncontrolling cumulative redeemable preferred units of the Operating Partnership (Note 9)	(3,541)	(5,588)	(5,588)
Preferred dividends (Note 10)	(10,567)	(9,608)	(9,608)
Original issuance costs of redeemed preferred stock and preferred units (Notes 9 and 11)	6,980	0	0
Total preferred distributions	21,088	15,196	15,196
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS	$ 249,826	$ 50,819	$ 4,512
Loss from continuing operations available to common stockholders per common share-basic (Note 19)	$ (0.24)	$ (0.35)	$ (0.33)
Loss from continuing operations available to common stockholders per common share-diluted (Note 19)	$ (0.24)	$ (0.35)	$ (0.33)
Net income available to common stockholders per share-basic (Note 19)	$ 3.56	$ 0.87	$ 0.07
Net income available to common stockholders per share-diluted (Note 19)	$ 3.56	$ 0.87	$ 0.07
Weighted average common shares outstanding-basic (Note 19)	69,639,623	56,717,121	49,497,487
Weighted average common shares outstanding-diluted (Note 19	69,639,623	56,717,121	49,497,487
Dividends declared per common share	$ 1.4	$ 1.4	$ 1.4