Consolidated Statements of Operations (KILROY REALTY, L.P.) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
REVENUES
Revenue	$ 186,562	$ 181,534	$ 556,456	$ 541,440
EXPENSES
Real estate taxes	17,462	16,371	52,421	50,878
Provision for bad debts (Note 12)	1,338	1,036	6,714	2,743
Ground leases	1,579	1,562	4,726	4,751
General and administrative expenses	19,277	14,514	56,599	43,750
Depreciation and amortization	62,700	62,567	189,421	185,737
Total expenses	137,519	129,120	409,282	385,474
OTHER (EXPENSES) INCOME
Interest income and other net investment gain/loss (Note 11)	342	1,526	1,147	3,629
Interest expense (Note 5)	(11,075)	(16,151)	(37,285)	(51,476)
Total other (expenses) income	(10,733)	(14,625)	(36,138)	(47,847)
INCOME FROM OPERATIONS BEFORE GAINS ON SALES OF REAL ESTATE	38,310	37,789	111,036	108,119
Net gain on sale of land	0	449	0	449
Gains on sales of depreciable operating properties	0	37,250	0	39,507
NET INCOME	38,310	75,488	111,036	148,075
Net income attributable to noncontrolling interests in consolidated property partnerships and subsidiaries	(3,910)	(4,378)	(12,841)	(11,992)
NET INCOME ATTRIBUTABLE TO KILROY REALTY CORPORATION (KILROY REALTY, L.P.)	34,400	71,110	98,195	136,083
Preferred distributions	0	(808)	0	(5,774)
Original issuance costs of redeemed preferred stock and preferred units	0	(3,744)	0	(7,589)
Total preferred distributions	0	(4,552)	0	(13,363)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS (UNITHOLDERS)	$ 34,400	$ 66,558	$ 98,195	$ 122,720
Net income available to common unitholders per unit-basic (in dollars per unit) (Note 14)	$ 0.34	$ 0.67	$ 0.97	$ 1.24
Net income available to common unitholders per unit-diluted (in dollars per unit) (Note 14)	$ 0.33	$ 0.67	$ 0.97	$ 1.23
Weighted average common shares outstanding – basic (in units) (Note 14)	100,676,778	98,352,139	99,711,312	98,008,780
Weighted average common units outstanding - diluted (in units) (Note 14)	101,228,334	98,911,612	100,208,645	98,591,048
Rental [Member]
REVENUES
Revenue	$ 162,288	$ 159,954	$ 489,674	$ 475,527
Tenant reimbursements [Member]
REVENUES
Revenue	21,754	19,665	60,471	58,228
Other property income [Member]
REVENUES
Revenue	2,520	1,915	6,311	7,685
Property [Member]
EXPENSES
Property expenses	35,163	33,070	99,401	97,615
Kilroy Realty L.P. [Member]
REVENUES
Revenue	186,562	181,534	556,456	541,440
EXPENSES
Real estate taxes	17,462	16,371	52,421	50,878
Provision for bad debts (Note 12)	1,338	1,036	6,714	2,743
Ground leases	1,579	1,562	4,726	4,751
General and administrative expenses	19,277	14,514	56,599	43,750
Depreciation and amortization	62,700	62,567	189,421	185,737
Total expenses	137,519	129,120	409,282	385,474
OTHER (EXPENSES) INCOME
Interest income and other net investment gain/loss (Note 11)	342	1,526	1,147	3,629
Interest expense (Note 5)	(11,075)	(16,151)	(37,285)	(51,476)
Total other (expenses) income	(10,733)	(14,625)	(36,138)	(47,847)
INCOME FROM OPERATIONS BEFORE GAINS ON SALES OF REAL ESTATE	38,310	37,789	111,036	108,119
Net gain on sale of land	0	449	0	449
Gains on sales of depreciable operating properties	0	37,250	0	39,507
NET INCOME	38,310	75,488	111,036	148,075
Net income attributable to noncontrolling interests in consolidated property partnerships and subsidiaries	(3,317)	(3,086)	(11,135)	(9,648)
NET INCOME ATTRIBUTABLE TO KILROY REALTY CORPORATION (KILROY REALTY, L.P.)	34,993	72,402	99,901	138,427
Preferred distributions	0	(808)	0	(5,774)
Original issuance costs of redeemed preferred stock and preferred units	0	(3,744)	0	(7,589)
Total preferred distributions	0	(4,552)	0	(13,363)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS (UNITHOLDERS)	$ 34,993	$ 67,850	$ 99,901	$ 125,064
Net income available to common unitholders per unit-basic (in dollars per unit) (Note 14)	$ 0.34	$ 0.67	$ 0.97	$ 1.23
Net income available to common unitholders per unit-diluted (in dollars per unit) (Note 14)	$ 0.33	$ 0.67	$ 0.96	$ 1.23
Weighted average common shares outstanding – basic (in units) (Note 14)	102,721,806	100,429,332	101,773,540	100,160,595
Weighted average common units outstanding - diluted (in units) (Note 14)	103,273,362	100,988,805	102,270,873	100,742,863
Dividends declared per common unit (in dollars per unit)	$ 0.455000	$ 0.425000	$ 1.335000	$ 1.225000
Kilroy Realty L.P. [Member] | Rental [Member]
REVENUES
Revenue	$ 162,288	$ 159,954	$ 489,674	$ 475,527
Kilroy Realty L.P. [Member] | Tenant reimbursements [Member]
REVENUES
Revenue	21,754	19,665	60,471	58,228
Kilroy Realty L.P. [Member] | Other property income [Member]
REVENUES
Revenue	2,520	1,915	6,311	7,685
Kilroy Realty L.P. [Member] | Property [Member]
EXPENSES
Property expenses	$ 35,163	$ 33,070	$ 99,401	$ 97,615