Consolidated Balance Sheets (KILROY REALTY, L.P.) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
REAL ESTATE ASSETS (Notes 3, 17, and 18):
Land and improvements	$ 612,714	$ 537,574
Buildings and improvements	3,335,026	2,830,310
Undeveloped land and construction in progress	809,654	430,806
Total real estate held for investment	4,757,394	3,798,690
Accumulated depreciation and amortization	(756,515)	(742,503)
Total real estate held for investment, net ($319,770 and $101,352 of VIE, Note 2)	4,000,879	3,056,187
REAL ESTATE ASSETS AND OTHER ASSETS HELD FOR SALE, NET (Note 17)	0	84,156
CASH AND CASH EQUIVALENTS	16,700	4,777
RESTRICTED CASH (Note 17)	247,544	358
MARKETABLE SECURITIES (Notes 13 and 16)	7,435	5,691
CURRENT RECEIVABLES, NET (Note 5)	9,220	8,395
DEFERRED RENT RECEIVABLES, NET (Note 5)	115,418	101,142
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Notes 3 and 4)	189,968	155,522
DEFERRED FINANCING COSTS, NET (Notes 2 and 7)	18,971	18,368
PREPAID EXPENSES AND OTHER ASSETS, NET	9,949	12,199
Total Assets	4,616,084	3,446,795
LIABILITIES:
Secured debt (Notes 3, 6, 7 and 16)	561,096	351,825
Exchangeable senior notes, net (Notes 6, 7 and 16)	163,944	306,892
Unsecured debt, net (Notes 6, 7 and 16)	1,130,895	980,569
Unsecured line of credit (Notes 6, 7 and 16)	185,000	182,000
Accounts payable, accrued expenses and other liabilities (Note 15)	154,734	81,713
Accrued distributions (Note 10)	28,924	22,692
Deferred revenue and acquisition-related intangible liabilities, net (Notes 3, 4 and 8)	117,904	79,781
Rents received in advance and tenant security deposits	37,654	26,917
Liabilities and deferred revenue of real estate assets held for sale (Note 17)	0	13,286
Total liabilities	2,380,151	2,045,675
COMMITMENTS AND CONTINGENCIES (Note 15)
7.45% SERIES A CUMULATIVE REDEEMABLE PREFERRED UNITS (Note 9)	0	73,638
Partners' Capital:
Cumulative Redeemable Preferred stock	0	0
TOTAL LIABILITIES, NONCONTROLLING INTEREST AND CAPITAL	4,616,084	3,446,795
Kilroy Realty, L.P. [Member]
REAL ESTATE ASSETS (Notes 3, 17, and 18):
Land and improvements	612,714	537,574
Buildings and improvements	3,335,026	2,830,310
Undeveloped land and construction in progress	809,654	430,806
Total real estate held for investment	4,757,394	3,798,690
Accumulated depreciation and amortization	(756,515)	(742,503)
Total real estate held for investment, net ($319,770 and $101,352 of VIE, Note 2)	4,000,879	3,056,187
REAL ESTATE ASSETS AND OTHER ASSETS HELD FOR SALE, NET (Note 17)	0	84,156
CASH AND CASH EQUIVALENTS	16,700	4,777
RESTRICTED CASH (Note 17)	247,544	358
MARKETABLE SECURITIES (Notes 13 and 16)	7,435	5,691
CURRENT RECEIVABLES, NET (Note 5)	9,220	8,395
DEFERRED RENT RECEIVABLES, NET (Note 5)	115,418	101,142
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Notes 3 and 4)	189,968	155,522
DEFERRED FINANCING COSTS, NET (Notes 2 and 7)	18,971	18,368
PREPAID EXPENSES AND OTHER ASSETS, NET	9,949	12,199
Total Assets	4,616,084	3,446,795
LIABILITIES:
Secured debt (Notes 3, 6, 7 and 16)	561,096	351,825
Exchangeable senior notes, net (Notes 6, 7 and 16)	163,944	306,892
Unsecured debt, net (Notes 6, 7 and 16)	1,130,895	980,569
Unsecured line of credit (Notes 6, 7 and 16)	185,000	182,000
Accounts payable, accrued expenses and other liabilities (Note 15)	154,734	81,713
Accrued distributions (Note 10)	28,924	22,692
Deferred revenue and acquisition-related intangible liabilities, net (Notes 3, 4 and 8)	117,904	79,781
Rents received in advance and tenant security deposits	37,654	26,917
Liabilities and deferred revenue of real estate assets held for sale (Note 17)	0	13,286
Total liabilities	2,380,151	2,045,675
COMMITMENTS AND CONTINGENCIES (Note 15)
7.45% SERIES A CUMULATIVE REDEEMABLE PREFERRED UNITS (Note 9)	0	73,638
Partners' Capital:
Common units, 74,926,981 and 58,819,717 held by the general partner and 1,826,503 and 1,718,131 held by common limited partners issued and outstanding, respectively	2,040,243	1,203,259
Total Partners' Capital	2,232,654	1,324,841
Noncontrolling interests in consolidated subsidiaries	3,279	2,641
Total capital	2,235,933	1,327,482
TOTAL LIABILITIES, NONCONTROLLING INTEREST AND CAPITAL	4,616,084	3,446,795
Kilroy Realty, L.P. [Member] | Series E Cumulative Redeemable Preferred Unit [Member]
Partners' Capital:
Cumulative Redeemable Preferred stock	0	38,425
Kilroy Realty, L.P. [Member] | Series F Cumulative Redeemable Preferred Unit [Member]
Partners' Capital:
Cumulative Redeemable Preferred stock	0	83,157
Kilroy Realty, L.P. [Member] | Series G Cumulative Redeemable Preferred Unit [Member]
Partners' Capital:
Cumulative Redeemable Preferred stock	96,155	0
Kilroy Realty, L.P. [Member] | Series H Cumulative Redeemable Preferred Unit [Member]
Partners' Capital:
Cumulative Redeemable Preferred stock	$ 96,256	$ 0