Consolidated Statements of Cash Flows (KILROY REALTY, L.P.) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 21,518	$ 83,471
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	148,982	122,754
Increase (decrease) in provision for bad debts	196	(192)
Depreciation of furniture, fixtures and equipment	1,363	896
Noncash amortization of share-based compensation awards	6,454	5,544
Noncash amortization of deferred financing costs and debt discounts and premiums	4,047	7,078
Noncash amortization of net below market rents (Note 3)	(6,015)	(4,616)
Net gain on dispositions of discontinued operations (Note 12)	(423)	(72,809)
Noncash amortization of deferred revenue related to tenant-funded tenant improvements	(7,585)	(6,851)
Straight-line rents	(18,188)	(16,433)
Net change in other operating assets	(6,435)	(2,529)
Net change in other operating liabilities	42,844	31,965
Insurance proceeds received for property damage	(448)	(951)
Net cash provided by operating activities	186,310	147,327
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisition of operating properties (Note 2)	(202,682)	(393,133)
Expenditures for acquistion of development and redevelopment properties (Note 2)	13,269	163,271
Expenditures for operating properties	(83,991)	(60,967)
Expenditures for development and redevelopment properties and undeveloped land	(222,192)	(52,937)
Net proceeds received from dispositions of operating properties	14,409	141,810
Insurance proceeds received for property damage	448	951
Increase in acquisition-related deposits	(4,000)	(8,250)
Decrease (increase) in restricted cash (Note 1)	229,613	(5,526)
Net cash used in investing activities	(281,664)	(541,323)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of Series G and Series H preferred stock	0	192,411
Borrowings on unsecured line of credit	10,000	418,000
Repayments on unsecured line of credit	(195,000)	(573,000)
Proceeds from issuance of secured debt	0	97,000
Principal payments on secured debt	(91,298)	(104,578)
Proceeds from the issuance of unsecured debt (Note 5)	299,901	150,000
Repayments of exchangeable senior notes	0	(148,000)
Financing costs	(3,975)	(5,396)
Repurchase of common stock and restricted stock units (Note 9)	(1,813)	(736)
Proceeds from exercise of stock options	128	129
Distributions paid to common unitholders	(82,152)	(70,517)
Distributions paid to preferred unitholders	(9,938)	(10,852)
Net cash provided by financing activities	275,804	405,332
Net increase in cash and cash equivalents	180,450	11,336
Cash and cash equivalents, beginning of period	16,700	4,777
Cash and cash equivalents, end of period	197,150	16,113
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $23,573 and $11,531 as of September 30, 2013 and 2012, respectively	47,107	49,378
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	79,866	8,299
Tenant improvements funded directly by tenants	5,750	16,303
Assumption of secured debt in connection with property acquisitions (Notes 2 and 5)	95,496	177,678
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 2)	422	11,667
Contribution of land, net of related liabilities, by noncontrolling interest to consolidated subsidiary (Note 2)	4,885	0
NONCASH FINANCING TRANSACTIONS:
Accrual of distributions payable to common unitholders	29,378	26,782
Accrual of distributions payable to preferred unitholders	1,692	1,693
Grant date fair value of share-based compensation awards (Note 9)	10,347	30,929
Issuance of common units in the Operating Partnership in connection with an operating property acquisition	4,885	5,604
Series A Preferred Units [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	0	75,000
Kilroy Realty, L.P. [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	21,518	83,471
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	148,982	122,754
Increase (decrease) in provision for bad debts	196	(192)
Depreciation of furniture, fixtures and equipment	1,363	896
Noncash amortization of share-based compensation awards	6,454	5,544
Noncash amortization of deferred financing costs and debt discounts and premiums	4,047	7,078
Noncash amortization of net below market rents (Note 3)	(6,015)	(4,616)
Net gain on dispositions of discontinued operations (Note 12)	(423)	(72,809)
Noncash amortization of deferred revenue related to tenant-funded tenant improvements	(7,585)	(6,851)
Straight-line rents	(18,188)	(16,433)
Net change in other operating assets	(6,435)	(2,529)
Net change in other operating liabilities	42,844	31,965
Insurance proceeds received for property damage	(448)	(951)
Net cash provided by operating activities	186,310	147,327
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisition of operating properties (Note 2)	(202,682)	(393,133)
Expenditures for acquistion of development and redevelopment properties (Note 2)	13,269	163,271
Expenditures for operating properties	(83,991)	(60,967)
Expenditures for development and redevelopment properties and undeveloped land	(222,192)	(52,937)
Net proceeds received from dispositions of operating properties	14,409	141,810
Insurance proceeds received for property damage	448	951
Increase in acquisition-related deposits	(4,000)	(8,250)
Decrease (increase) in restricted cash (Note 1)	229,613	(5,526)
Net cash used in investing activities	(281,664)	(541,323)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common units (Note 8)	349,951	662,371
Net proceeds from issuance of Series G and Series H preferred stock	0	192,411
Borrowings on unsecured line of credit	10,000	418,000
Repayments on unsecured line of credit	(195,000)	(573,000)
Proceeds from issuance of secured debt	0	97,000
Principal payments on secured debt	(91,298)	(104,578)
Proceeds from the issuance of unsecured debt (Note 5)	299,901	150,000
Repayments of exchangeable senior notes	0	(148,000)
Financing costs	(3,975)	(5,396)
Repurchase of common stock and restricted stock units (Note 9)	(1,813)	(736)
Proceeds from exercise of stock options	128	129
Distributions paid to common unitholders	(82,152)	(70,517)
Distributions paid to preferred unitholders	(9,938)	(10,852)
Net cash provided by financing activities	275,804	405,332
Net increase in cash and cash equivalents	180,450	11,336
Cash and cash equivalents, beginning of period	16,700	4,777
Cash and cash equivalents, end of period	197,150	16,113
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $23,573 and $11,531 as of September 30, 2013 and 2012, respectively	47,107	49,378
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	79,866	8,299
Tenant improvements funded directly by tenants	5,750	16,303
Assumption of secured debt in connection with property acquisitions (Notes 2 and 5)	95,496	177,678
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 2)	422	11,667
NONCASH FINANCING TRANSACTIONS:
Accrual of distributions payable to common unitholders	29,378	26,782
Accrual of distributions payable to preferred unitholders	1,692	1,693
Grant date fair value of share-based compensation awards (Note 9)	10,347	30,929
Issuance of common units in the Operating Partnership in connection with an operating property acquisition	4,885	5,604
Kilroy Realty, L.P. [Member] | Series A Preferred Units [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	0
Series E and Series F Cumulative Redeemable Preferred Stock [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock	0	(126,500)
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	0	126,500
Series A Preferred Units [Member] | Kilroy Realty, L.P. [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Payments for Repurchase of Redeemable Preferred Stock		$ 75,000