Consolidated Statements of Cash Flows (KILROY REALTY, L.P.) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 277,101	$ 67,489	$ 19,886
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization of building and improvements and leasing costs	168,687	135,467	102,898
(Decrease) increase in provision for bad debts	(42)	644	(1,063)
Depreciation of furniture, fixtures and equipment	1,213	1,130	911
Noncash amortization of share-based compensation awards (Note 12)	7,670	4,482	6,031
Noncash amortization of deferred financing costs and net debt discounts	8,433	13,540	12,490
Noncash amortization of net (below)/above market rents (Note 4)	(6,699)	1,056	1,377
Net gain on dispositions of discontinued operations (Note 17)	(259,245)	(51,587)	(949)
Noncash amortization of deferred revenue related to tenant-funded tenant improvements (Note 8)	(9,136)	(9,349)	(9,689)
Straight-line rents	(21,530)	(21,331)	(13,616)
Loss on early extinguishment of debt (Note 7)	0	0	4,564
Net change in operating assets	(1,297)	(5,434)	(9,065)
Net change in operating liabilities	17,320	2,779	5,509
Insurance proceeds received for property damage and other, net	(1,751)	(630)	543
Net cash provided by operating activities	180,724	138,256	119,827
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisition of operating properties (Note 3)	(454,841)	(603,301)	(637,620)
Expenditures for acquisitions of development and redevelopment properties (Note 3)	(333,942)	0	0
Expenditures for operating properties	(86,377)	(62,739)	(71,099)
Expenditures for development and redevelopment properties and undeveloped land	(83,310)	(28,517)	(21,832)
Net proceeds received from dispositions of operating properties (Note 17)	263,572	64,171	14,978
Insurance proceeds received for property damage	1,751	0	0
Decrease (increase) in acquisition-related deposits	5,000	(5,000)	0
(Increase) decrease in restricted cash (Note 3)	(18,359)	1,103	3,120
Receipt of principal payments on note receivable	0	0	10,679
Net cash used in investing activities	(706,506)	(634,283)	(701,774)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Series G and Series H preferred stock (Note 10)	192,411	0	0
Payments for Repurchase of Redeemable Preferred Stock			0
Borrowings on unsecured line of credit	704,000	550,000	660,000
Repayments on unsecured line of credit	(701,000)	(527,000)	(598,000)
Proceeds from issuance of secured debt (Note 7)	97,000	135,000	71,000
Principal payments on secured debt	(106,262)	(127,665)	(103,247)
Proceeds from the issuance of unsecured senior notes (Note 7)	150,000	324,476	572,672
Repayments of unsecured debt (Note 7)	0	0	(61,000)
Repurchase of exchangeable senior notes (Note 7)	0	0	(151,097)
Repayments of exchangeable senior notes (Note 7)	(148,000)	0	0
Financing costs	(7,963)	(9,060)	(14,912)
Decrease (increase) in loan deposits and other	0	2,859	(605)
Repurchase/redemption of common units and restricted stock units	(1,661)	(1,152)	(3,417)
Proceeds from exercise of stock options	129	395	83
Distributions paid to common unitholders	(97,386)	(80,005)	(69,224)
Distributions paid to preferred unitholders	(14,165)	(15,196)	(15,196)
Net cash provided by financing activities	537,705	485,964	586,904
Net increase (decrease) in cash and cash equivalents	11,923	(10,063)	4,957
Cash and cash equivalents, beginning of period	4,777	14,840	9,883
Cash and cash equivalents, end of period	16,700	4,777	14,840
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $17,657, $7,615, and $7,697 as of December 31, 2012, 2011 and 2010, respectively	71,633	68,280	45,986
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	54,198	14,301	19,563
Tenant improvements funded directly by tenants to third parties	17,719	3,288	4,758
Assumption of secured debt with property acquisition (Notes 3 and 7)	221,032	30,042	51,079
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 3)	37,535	4,515	10,840
NONCASH FINANCING TRANSACTIONS:
Accrual of distributions payable to common unitholders (Note 11)	26,863	21,188	18,925
Accrual of distributions payable to preferred unitholders (Note 11)	1,694	1,909	1,909
Issuance of share-based compensation awards (Note 12)	31,396	7,797	5,910
Issuance of common units in the Operating Partnership in connection with an operating property acquisition (Note 3)	5,604	0	0
Kilroy Realty, L.P. [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	277,101	67,489	19,886
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization of building and improvements and leasing costs	168,687	135,467	102,898
(Decrease) increase in provision for bad debts	(42)	644	(1,063)
Depreciation of furniture, fixtures and equipment	1,213	1,130	911
Noncash amortization of share-based compensation awards (Note 12)	7,670	4,482	6,031
Noncash amortization of deferred financing costs and net debt discounts	8,433	13,540	12,490
Noncash amortization of net (below)/above market rents (Note 4)	(6,699)	1,056	1,377
Net gain on dispositions of discontinued operations (Note 17)	(259,245)	(51,587)	(949)
Noncash amortization of deferred revenue related to tenant-funded tenant improvements (Note 8)	(9,136)	(9,349)	(9,689)
Straight-line rents	(21,530)	(21,331)	(13,616)
Loss on early extinguishment of debt (Note 7)	0	0	4,564
Net change in operating assets	(1,297)	(5,434)	(9,065)
Net change in operating liabilities	17,320	2,779	5,509
Insurance proceeds received for property damage and other, net	(1,751)	(630)	543
Net cash provided by operating activities	180,724	138,256	119,827
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisition of operating properties (Note 3)	(454,841)	(603,301)	(637,620)
Expenditures for acquisitions of development and redevelopment properties (Note 3)	(333,942)	0	0
Expenditures for operating properties	(86,377)	(62,739)	(71,099)
Expenditures for development and redevelopment properties and undeveloped land	(83,310)	(28,517)	(21,832)
Net proceeds received from dispositions of operating properties (Note 17)	263,572	64,171	14,978
Insurance proceeds received for property damage	1,751	0	0
Decrease (increase) in acquisition-related deposits	5,000	(5,000)	0
(Increase) decrease in restricted cash (Note 3)	(18,359)	1,103	3,120
Receipt of principal payments on note receivable	0	0	10,679
Net cash used in investing activities	(706,506)	(634,283)	(701,774)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Series G and Series H preferred stock (Note 10)	192,411	0	0
Net proceeds from issuance of common units (Note 10)	672,102	233,312	299,847
Borrowings on unsecured line of credit	704,000	550,000	660,000
Repayments on unsecured line of credit	(701,000)	(527,000)	(598,000)
Proceeds from issuance of secured debt (Note 7)	97,000	135,000	71,000
Principal payments on secured debt	(106,262)	(127,665)	(103,247)
Proceeds from the issuance of unsecured senior notes (Note 7)	150,000	324,476	572,672
Repayments of unsecured debt (Note 7)	0	0	(61,000)
Repurchase of exchangeable senior notes (Note 7)	0	0	(151,097)
Repayments of exchangeable senior notes (Note 7)	(148,000)	0	0
Financing costs	(7,963)	(9,060)	(14,912)
Decrease (increase) in loan deposits and other	0	2,859	(605)
Repurchase/redemption of common units and restricted stock units	(1,661)	(1,152)	(3,417)
Proceeds from exercise of stock options	129	395	83
Distributions paid to common unitholders	(97,386)	(80,005)	(69,224)
Distributions paid to preferred unitholders	(14,165)	(15,196)	(15,196)
Net cash provided by financing activities	537,705	485,964	586,904
Net increase (decrease) in cash and cash equivalents	11,923	(10,063)	4,957
Cash and cash equivalents, beginning of period	4,777	14,840	9,883
Cash and cash equivalents, end of period	16,700	4,777	14,840
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $17,657, $7,615, and $7,697 as of December 31, 2012, 2011 and 2010, respectively	71,633	68,280	45,986
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	54,198	14,301	19,563
Tenant improvements funded directly by tenants to third parties	17,719	3,288	4,758
Assumption of secured debt with property acquisition (Notes 3 and 7)	221,032	30,042	51,079
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 3)	37,535	4,515	10,840
NONCASH FINANCING TRANSACTIONS:
Accrual of distributions payable to common unitholders (Note 11)	26,863	21,188	18,925
Accrual of distributions payable to preferred unitholders (Note 11)	1,694	1,909	1,909
Issuance of share-based compensation awards (Note 12)	31,396	7,797	5,910
Issuance of common units in the Operating Partnership in connection with an operating property acquisition (Note 3)	5,604	0	0
Series E and Series F Cumulative Redeemable Preferred Stock [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	(126,500)	0
Series E and Series F Cumulative Redeemable Preferred Stock [Member] | Kilroy Realty, L.P. [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	(126,500)	0	0
Series A Preferred Units [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	(75,000)	0
Series A Preferred Units [Member] | Kilroy Realty, L.P. [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	$ (75,000)	$ 0	$ 0