Kilroy Realty (KRC) 10-K 13 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 07, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	1-12675
Entity Registrant Name	KILROY REALTY CORPORATION
Entity Central Index Key	0001025996
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	95-4598246
Entity Address, Address Line One	12200 W. Olympic Boulevard
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Los Angeles
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90064
City Area Code	(310)
Local Phone Number	481-8400
Title of 12(b) Security	Common Stock, $.01 par value
Security Exchange Name	NYSE
Trading Symbol	KRC
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 7,416,459,726
Entity Common Stock, Shares Outstanding		106,167,149
Documents Incorporated by Reference	Portions of the Kilroy Realty Corporation’s Proxy Statement with respect to its 2020 Annual Meeting of Stockholders to be filed not later than 120 days after the end of the registrant’s fiscal year are incorporated by reference into Part III of this Form 10-K.
Kilroy Realty L.P. [Member]
Entity Information [Line Items]
Entity File Number	000-54005
Entity Registrant Name	KILROY REALTY, L.P.
Entity Central Index Key	0001493976
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	95-4612685
Title of 12(g) Security	Common Units Representing Limited Partnership Interests
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
REAL ESTATE ASSETS
Land and improvements	$ 1,466,166	$ 1,160,138
Buildings and improvements	5,866,477	5,207,984
Undeveloped land and construction in progress	2,296,130	2,058,510
Total real estate assets held for investment	9,628,773	8,426,632
Accumulated depreciation and amortization	(1,561,361)	(1,391,368)
Total real estate assets held for investment, net	8,067,412	7,035,264
CASH AND CASH EQUIVALENTS (Note 23)	60,044	51,604
RESTRICTED CASH (Notes 3, 4 and 23)	16,300	119,430
MARKETABLE SECURITIES (Notes 16 and 19)	27,098	21,779
CURRENT RECEIVABLES, NET (Notes 2, 6 and 20)	26,489	20,176
DEFERRED RENT RECEIVABLES, NET (Notes 2, 6 and 20)	337,937	267,007
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Notes 2, 3 and 5)	212,805	197,574
RIGHT OF USE GROUND LEASE ASSETS (Notes 2 and 18)	96,348
PREPAID EXPENSES AND OTHER ASSETS, NET (Note 7)	55,661	52,873
TOTAL ASSETS	8,900,094	7,765,707
LIABILITIES:
Secured debt, net (Notes 8, 9 and 19)	258,593	335,531
Unsecured debt, net (Notes 8, 9 and 19)	3,049,185	2,552,070
Unsecured line of credit (Notes 8, 9 and 19)	245,000	45,000
Accounts payable, accrued expenses and other liabilities (Note 18)	418,848	374,415
Ground lease liabilities (Notes 2 and 18)	98,400
Accrued dividends and distributions (Notes 13 and 28)	53,219	47,559
Deferred revenue and acquisition-related intangible liabilities, net (Notes 3, 5 and 10)	139,488	149,646
Rents received in advance and tenant security deposits	66,503	60,225
Total liabilities	4,329,236	3,564,446
COMMITMENTS AND CONTINGENCIES (Note 18)
Stockholders’ Equity (Note 13):
Common stock, $.01 par value, 150,000,000 shares authorized, 106,016,287 and 100,746,988 shares issued and outstanding, respectively	1,060	1,007
Additional paid-in capital	4,350,917	3,976,953
Distributions in excess of earnings	(58,467)	(48,053)
Total stockholders’ equity	4,293,510	3,929,907
Noncontrolling Interests (Notes 2 and 11):
Common units of the Operating Partnership	81,917	78,991
Noncontrolling interests in consolidated property partnerships	195,431	192,363
Total noncontrolling interests	277,348	271,354
Total equity	4,570,858	4,201,261
TOTAL LIABILITIES AND EQUITY/CAPITAL	$ 8,900,094	$ 7,765,707

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued (in shares)	106,016,287	100,746,988
Common stock, shares outstanding	106,016,287	100,746,988

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REVENUES (Note 2):
Revenues	$ 837,454	$ 747,298	$ 719,001
EXPENSES:
Real estate taxes (Note 2)	78,097	70,820	66,449
Provision for bad debts (Notes 2 and 20)	0	5,685	3,269
Ground leases (Notes 2, 5 and 18)	8,113
Ground leases (Notes 2, 5 and 18)		6,176	6,337
General and administrative expenses (Note 15)	88,139	90,471	60,581
Leasing costs (Notes 2 and 5)	7,615
Depreciation and amortization (Notes 2 and 5)	273,130	254,281	245,886
Total expenses	615,131	561,220	512,493
OTHER (EXPENSES) INCOME:
Interest income and other net investment gain (loss) (Note 19)	4,641	(559)	5,503
Interest expense (Note 9)	(48,537)	(49,721)	(66,040)
Loss on early extinguishment of debt (Note 9)	0	(12,623)	(5,312)
Net gain on sales of land (Note 4)	0	11,825	449
Gains on sales of depreciable operating properties (Note 4)	36,802	142,926	39,507
Total other (expenses) income	(7,094)	91,848	(25,893)
NET INCOME	215,229	277,926	180,615
Net income attributable to noncontrolling common units of the Operating Partnership (Notes 2 and 11)	(3,766)	(5,193)	(3,223)
Net income attributable to noncontrolling interests in consolidated property partnerships (Notes 2 and 11)	(16,020)	(14,318)	(12,780)
Total income attributable to noncontrolling interests	(19,786)	(19,511)	(16,003)
NET INCOME ATTRIBUTABLE TO KILROY REALTY CORPORATION / KILROY REALTY, L.P.	195,443	258,415	164,612
Preferred dividends (Note 13)	0	0	(5,774)
Original issuance costs of redeemed preferred stock and preferred units (Note 13)	0	0	(7,589)
Total preferred dividends	0	0	(13,363)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS (UNITHOLDERS)	$ 195,443	$ 258,415	$ 151,249
Net income available to common stockholders per share - basic (in dollars per share)	$ 1.87	$ 2.56	$ 1.52
Net income available to common stockholders per share - diluted (in dollars per share)	$ 1.86	$ 2.55	$ 1.51
Weighted average shares of common stock outstanding – basic (in shares)	103,200,568	99,972,359	98,113,561
Weighted average shares of common stock outstanding – diluted (in shares)	103,849,168	100,482,365	98,727,331
Rental income [Member]
REVENUES (Note 2):
Revenues	$ 826,472	$ 656,631	$ 633,896
Tenant reimbursements [Member]
REVENUES (Note 2):
Revenues	0	80,982	76,559
Other property income [Member]
REVENUES (Note 2):
Revenues	10,982	9,685	8,546
Property [Member]
EXPENSES:
Property expenses (Note 2)	$ 160,037	$ 133,787	$ 129,971

CONSOLIDATED STATEMENTS OF EQUI

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Total Stockholders' Equity	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Distributions in Excess of Earnings [Member]	Noncontrolling Interests [Member]
Beginning balance at Dec. 31, 2016	$ 3,759,317	$ 3,542,995	$ 192,411	$ 932	$ 3,457,649	$ (107,997)	$ 216,322
Beginning balance (in shares) at Dec. 31, 2016				93,219,439
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	180,615	164,612				164,612	16,003
Redemption of Series G & H Preferred stock	(200,000)	(200,000)	(192,411)			(7,589)
Issuance of common stock	326,058	326,058		$ 46	326,012
Issuance of common stock (in shares)				4,662,577
Issuance of share-based compensation awards	5,890	5,890			5,890
Non-cash amortization of share-based compensation	26,319	26,319			26,319
Exercise of stock options	12,179	12,179		$ 4	12,175
Exercise of stock options (in shares)				285,000
Settlement of restricted stock units for shares of common stock	0			$ 3	(3)
Settlement of restricted stock units for shares of common stock (in shares)				317,848
Repurchase of common stock, stock options and restricted stock units	(12,986)			$ (2)	(12,984)
Repurchase of common stock, stock options and restricted stock units (in shares)				(168,881)
Exchange of common units of the Operating Partnership	0	10,939		$ 3	10,936		(10,939)
Exchange of common units of the Operating Partnership (in shares)				304,350
Contributions from noncontrolling interests in consolidated property partnerships	54,604	0			0		54,604
Distributions to noncontrolling interests in consolidated property partnerships	(16,542)						(16,542)
Adjustment for noncontrolling interest in the Operating Partnership	0	(3,502)			(3,502)		3,502
Preferred dividends and distributions	(5,774)	(5,774)				(5,774)
Dividends declared per share of common stock and common unit	(169,364)	(165,937)				(165,937)	(3,427)
Ending balance at Dec. 31, 2017	3,960,316	3,700,793	0	$ 986	3,822,492	(122,685)	259,523
Ending balance (in shares) at Dec. 31, 2017				98,620,333
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	277,926	258,415				258,415	19,511
Issuance of common stock	130,693	130,693		$ 18	130,675
Issuance of common stock (in shares)				1,817,195
Issuance of share-based compensation awards	3,926	3,926			3,926
Non-cash amortization of share-based compensation	35,890	35,890			35,890
Exercise of stock options	41	41			41
Exercise of stock options (in shares)				1,000
Settlement of restricted stock units for shares of common stock	0			$ 4	(4)
Settlement of restricted stock units for shares of common stock (in shares)				488,354
Repurchase of common stock, stock options and restricted stock units	(16,553)	(16,553)		$ (2)	(16,551)
Repurchase of common stock, stock options and restricted stock units (in shares)				(231,800)
Exchange of common units of the Operating Partnership	0	1,962		$ 1	1,961		(1,962)
Exchange of common units of the Operating Partnership (in shares)				51,906
Contributions from noncontrolling interests in consolidated property partnerships	8,273						8,273
Distributions to noncontrolling interests in consolidated property partnerships	(11,803)						(11,803)
Adjustment for noncontrolling interest in the Operating Partnership	0	(1,477)			(1,477)		1,477
Dividends declared per share of common stock and common unit	(187,448)	(183,783)				(183,783)	(3,665)
Ending balance at Dec. 31, 2018	$ 4,201,261	3,929,907	0	$ 1,007	3,976,953	(48,053)	271,354
Ending balance (in shares) at Dec. 31, 2018	100,746,988			100,746,988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 215,229	195,443				195,443	19,786
Issuance of common stock	353,722	353,722		$ 50	353,672
Issuance of common stock (in shares)				5,000,000
Issuance of share-based compensation awards	4,664	4,664			4,664
Non-cash amortization of share-based compensation	32,813	32,813			32,813
Exercise of stock options	703	703			703
Exercise of stock options (in shares)				16,500
Settlement of restricted stock units for shares of common stock	0			$ 5	(5)
Settlement of restricted stock units for shares of common stock (in shares)				463,276
Repurchase of common stock, stock options and restricted stock units	(14,861)	(14,861)		$ (2)	(14,859)
Repurchase of common stock, stock options and restricted stock units (in shares)				(212,477)
Exchange of common units of the Operating Partnership	0	78			78		(78)
Distributions to noncontrolling interests in consolidated property partnerships	(12,952)						(12,952)
Adjustment for noncontrolling interest in the Operating Partnership	0	(3,102)			(3,102)		3,102
Dividends declared per share of common stock and common unit	(206,575)	(202,711)				(202,711)	(3,864)
Ending balance at Dec. 31, 2019	$ 4,570,858	$ 4,293,510	$ 0	$ 1,060	$ 4,350,917	$ (58,467)	$ 277,348
Ending balance (in shares) at Dec. 31, 2019	106,016,287			106,016,287

CONSOLIDATED STATEMENTS OF EQ_2

CONSOLIDATED STATEMENTS OF EQUITY (Parenthetical) - $ / shares	3 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share (in dollars per share)	$ 0.375	$ 0.375	$ 1.91000	$ 1.79	$ 1.65

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 215,229	$ 277,926	$ 180,615
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of real estate assets and leasing costs	268,045	249,882	241,862
Depreciation of non-real estate furniture, fixtures and equipment	5,085	4,400	4,024
(Recoveries of) provision for bad debts (Notes 2 and 20)	(3,433)	5,685	3,269
Non-cash amortization of share-based compensation awards (Note 15)	27,007	27,932	19,046
Non-cash amortization of deferred financing costs and net debt discounts	1,427	1,084	3,247
Non-cash amortization of net below market rents (Note 5)	(9,206)	(9,748)	(8,528)
Gains on sales of depreciable operating properties (Note 4)	(36,802)	(142,926)	(39,507)
Non-cash amortization of deferred revenue related to tenant-funded tenant improvements (Note 10)	(19,190)	(18,429)	(16,767)
Straight-line rents	(72,023)	(26,976)	(33,275)
Amortization of the right of use ground lease asset (Note 2)	683
Loss on early extinguishment of debt (Note 9)	0	12,623	5,312
(Gain) loss on sale of land (Note 4)	0	(11,825)	(449)
Net change in other operating assets	(14,476)	(7,930)	(17,732)
Net change in other operating liabilities	24,175	48,345	5,895
Net cash provided by operating activities	386,521	410,043	347,012
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for development properties and undeveloped land	(845,464)	(489,236)	(397,440)
Expenditures for acquisitions of development properties and undeveloped land (Note 3)	(173,291)	(311,299)	(19,829)
Expenditures for acquisitions of operating properties (Note 3)	(186,258)	(257,340)	0
Expenditures for operating properties and other capital assets	(147,687)	(166,440)	(88,425)
Net proceeds received from dispositions (Note 4)	124,421	364,300	182,492
Decrease (increase) in acquisition-related deposits	0	36,000
Decrease (increase) in acquisition-related deposits			(35,900)
Proceeds received from repayment of note receivable	0	15,100	0
Net cash used in investing activities	(1,228,279)	(808,915)	(359,102)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common stock (Note 13)	353,722	130,693	326,058
Redemption of Series G and H Preferred stock (Note 13)	0	0	(200,000)
Net proceeds from the issuance of unsecured debt (Note 9)	499,390	648,537	674,447
Repayments of unsecured debt (Note 9)	0	(261,823)	(519,024)
Borrowings on unsecured revolving credit facility	1,110,000	765,000	270,000
Repayments on unsecured revolving credit facility	(910,000)	(690,000)	(270,000)
Borrowings on unsecured debt (Note 9)	0	120,000	0
Principal payments and repayments of secured debt (Note 9)	(76,309)	(3,584)	(130,371)
Financing costs	(6,678)	(6,262)	(11,500)
Repurchase of common stock and restricted stock units (Note 15)	(14,556)	(16,553)	(12,986)
Proceeds from exercise of stock options	703	41	12,179
Contributions from noncontrolling interests in consolidated property partnerships (Note 11)	0	8,273	54,604
Distributions to noncontrolling interests in consolidated property partnerships	(12,952)	(11,803)	(16,542)
Dividends and distributions paid to common stockholders and common unitholders	(196,252)	(179,411)	(340,697)
Dividends and distributions paid to preferred stockholders and preferred unitholders	0	0	(7,409)
Net cash provided by (used in) financing activities	747,068	503,108	(171,241)
Net (decrease) increase in cash and cash equivalents and restricted cash	(94,690)	104,236	(183,331)
Cash and cash equivalents and restricted cash, beginning of year	171,034	66,798	250,129
Cash and cash equivalents and restricted cash, end of year	$ 76,344	$ 171,034	$ 66,798

CONSOLIDATED BALANCE SHEETS (KI

CONSOLIDATED BALANCE SHEETS (KILROY REALTY, L.P.) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
REAL ESTATE ASSETS
Land and improvements	$ 1,466,166	$ 1,160,138
Buildings and improvements	5,866,477	5,207,984
Undeveloped land and construction in progress	2,296,130	2,058,510
Total real estate assets held for investment	9,628,773	8,426,632
Accumulated depreciation and amortization	(1,561,361)	(1,391,368)
Total real estate assets held for investment, net	8,067,412	7,035,264
CASH AND CASH EQUIVALENTS (Note 24)	60,044	51,604
RESTRICTED CASH (Notes 3, 4 and 24)	16,300	119,430
MARKETABLE SECURITIES (Notes 16 and 19)	27,098	21,779
CURRENT RECEIVABLES, NET (Notes 2, 6 and 20)	26,489	20,176
DEFERRED RENT RECEIVABLES, NET (Notes 2, 6 and 20)	337,937	267,007
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Notes 2, 3 and 5)	212,805	197,574
RIGHT OF USE GROUND LEASE ASSETS (Notes 2 and 18)	96,348
PREPAID EXPENSES AND OTHER ASSETS, NET (Note 7)	55,661	52,873
TOTAL ASSETS	8,900,094	7,765,707
LIABILITIES:
Secured debt, net (Notes 9 and 19)	258,593	335,531
Unsecured debt, net (Notes 9 and 19)	3,049,185	2,552,070
Unsecured line of credit (Notes 9 and 19)	245,000	45,000
Accounts payable, accrued expenses and other liabilities (Note 18)	418,848	374,415
Ground lease liabilities (Notes 2 and 18)	98,400
Accrued distributions (Notes 14 and 28)	53,219	47,559
Deferred revenue and acquisition-related intangible liabilities, net (Notes 3, 5 and 10)	139,488	149,646
Rents received in advance and tenant security deposits	66,503	60,225
Total liabilities	4,329,236	3,564,446
COMMITMENTS AND CONTINGENCIES (Note 18)
Partners’ Capital:
TOTAL LIABILITIES AND EQUITY/CAPITAL	8,900,094	7,765,707
Kilroy Realty L.P. [Member]
REAL ESTATE ASSETS
Land and improvements	1,466,166	1,160,138
Buildings and improvements	5,866,477	5,207,984
Undeveloped land and construction in progress	2,296,130	2,058,510
Total real estate assets held for investment	9,628,773	8,426,632
Accumulated depreciation and amortization	(1,561,361)	(1,391,368)
Total real estate assets held for investment, net	8,067,412	7,035,264
CASH AND CASH EQUIVALENTS (Note 24)	60,044	51,604
RESTRICTED CASH (Notes 3, 4 and 24)	16,300	119,430
MARKETABLE SECURITIES (Notes 16 and 19)	27,098	21,779
CURRENT RECEIVABLES, NET (Notes 2, 6 and 20)	26,489	20,176
DEFERRED RENT RECEIVABLES, NET (Notes 2, 6 and 20)	337,937	267,007
DEFERRED LEASING COSTS AND ACQUISITION-RELATED INTANGIBLE ASSETS, NET (Notes 2, 3 and 5)	212,805	197,574
RIGHT OF USE GROUND LEASE ASSETS (Notes 2 and 18)	96,348
PREPAID EXPENSES AND OTHER ASSETS, NET (Note 7)	55,661	52,873
TOTAL ASSETS	8,900,094	7,765,707
LIABILITIES:
Secured debt, net (Notes 9 and 19)	258,593	335,531
Unsecured debt, net (Notes 9 and 19)	3,049,185	2,552,070
Unsecured line of credit (Notes 9 and 19)	245,000	45,000
Accounts payable, accrued expenses and other liabilities (Note 18)	418,848	374,415
Ground lease liabilities (Notes 2 and 18)	98,400
Accrued distributions (Notes 14 and 28)	53,219	47,559
Deferred revenue and acquisition-related intangible liabilities, net (Notes 3, 5 and 10)	139,488	149,646
Rents received in advance and tenant security deposits	66,503	60,225
Total liabilities	4,329,236	3,564,446
COMMITMENTS AND CONTINGENCIES (Note 18)
Partners’ Capital:
Common units, 106,016,287 and 100,746,988 held by the general partner and 2,023,287 and 2,025,287 held by common limited partners issued and outstanding, respectively (Note 14)	4,369,758	4,003,700
Total partners’ capital	4,369,758	4,003,700
Noncontrolling interests in consolidated property partnerships and subsidiaries (Notes 2 and 12)	201,100	197,561
Total capital	4,570,858	4,201,261
TOTAL LIABILITIES AND EQUITY/CAPITAL	$ 8,900,094	$ 7,765,707

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (KILROY REALTY, L.P.) (Parenthetical) - Common units [Member] - Kilroy Realty L.P. [Member] - shares	Dec. 31, 2019	Dec. 31, 2018
General partner, units issued (in units)	106,016,287	100,746,988
General partner, units outstanding (in units)	106,016,287	100,746,988
Limited partner, units issued (in units)	2,023,287	2,025,287
Limited partner, units outstanding (in units)	2,023,287	2,025,287

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS (KILROY REALTY, L.P.) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
REVENUES (Note 2):
Revenues	$ 837,454	$ 747,298	$ 719,001
EXPENSES:
Real estate taxes (Note 2)	78,097	70,820	66,449
Provision for bad debts (Notes 2 and 20)	0	5,685	3,269
Ground leases (Notes 2, 5 and 18)	8,113
Ground leases (Notes 2, 5 and 18)		6,176	6,337
General and administrative expenses (Note 15)	88,139	90,471	60,581
Leasing costs (Notes 2 and 5)	7,615
Depreciation and amortization (Notes 2 and 5)	273,130	254,281	245,886
Total expenses	615,131	561,220	512,493
OTHER (EXPENSES) INCOME:
Interest income and other net investment gain (loss) (Note 19)	4,641	(559)	5,503
Interest expense (Note 9)	(48,537)	(49,721)	(66,040)
Loss on early extinguishment of debt (Note 9)	0	(12,623)	(5,312)
Net gain on sales of land (Note 4)	0	11,825	449
Gains on sales of depreciable operating properties (Note 4)	36,802	142,926	39,507
Total other (expenses) income	(7,094)	91,848	(25,893)
NET INCOME	215,229	277,926	180,615
Net income attributable to noncontrolling interests in consolidated property partnerships and subsidiaries (Notes 2 and 12)	(19,786)	(19,511)	(16,003)
NET INCOME ATTRIBUTABLE TO KILROY REALTY CORPORATION / KILROY REALTY, L.P.	195,443	258,415	164,612
Preferred distributions (Note 14)	0	0	(5,774)
Original issuance costs of redeemed preferred units (Note 14)	0	0	(7,589)
Total preferred distributions	0	0	(13,363)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS (UNITHOLDERS)	$ 195,443	$ 258,415	$ 151,249
Net income available to common unitholders per unit - basic (in dollars per unit)	$ 1.87	$ 2.56	$ 1.52
Net income available to common unitholders per unit - diluted (in dollars per unit)	$ 1.86	$ 2.55	$ 1.51
Weighted average common units outstanding - basic (in shares)	103,200,568	99,972,359	98,113,561
Weighted average common units outstanding - diluted (in shares)	103,849,168	100,482,365	98,727,331
Rental income [Member]
REVENUES (Note 2):
Revenues	$ 826,472	$ 656,631	$ 633,896
Tenant reimbursements [Member]
REVENUES (Note 2):
Revenues	0	80,982	76,559
Other property income [Member]
REVENUES (Note 2):
Revenues	10,982	9,685	8,546
Property [Member]
EXPENSES:
Property expenses (Note 2)	160,037	133,787	129,971
Kilroy Realty L.P. [Member]
REVENUES (Note 2):
Revenues	837,454	747,298	719,001
EXPENSES:
Real estate taxes (Note 2)	78,097	70,820	66,449
Provision for bad debts (Notes 2 and 20)	0	5,685	3,269
Ground leases (Notes 2, 5 and 18)	8,113
Ground leases (Notes 2, 5 and 18)		6,176	6,337
General and administrative expenses (Note 15)	88,139	90,471	60,581
Leasing costs (Notes 2 and 5)	7,615
Depreciation and amortization (Notes 2 and 5)	273,130	254,281	245,886
Total expenses	615,131	561,220	512,493
OTHER (EXPENSES) INCOME:
Interest income and other net investment gain (loss) (Note 19)	4,641	(559)	5,503
Interest expense (Note 9)	(48,537)	(49,721)	(66,040)
Loss on early extinguishment of debt (Note 9)	0	(12,623)	(5,312)
Net gain on sales of land (Note 4)	0	11,825	449
Gains on sales of depreciable operating properties (Note 4)	36,802	142,926	39,507
Total other (expenses) income	(7,094)	91,848	(25,893)
NET INCOME	215,229	277,926	180,615
Net income attributable to noncontrolling interests in consolidated property partnerships and subsidiaries (Notes 2 and 12)	(16,491)	(14,716)	(13,175)
NET INCOME ATTRIBUTABLE TO KILROY REALTY CORPORATION / KILROY REALTY, L.P.	198,738	263,210	167,440
Preferred distributions (Note 14)	0	0	(5,774)
Original issuance costs of redeemed preferred units (Note 14)	0	0
Total preferred distributions	0	0	(13,363)
NET INCOME AVAILABLE TO COMMON STOCKHOLDERS (UNITHOLDERS)	$ 198,738	$ 263,210	$ 154,077
Net income available to common unitholders per unit - basic (in dollars per unit)	$ 1.87	$ 2.56	$ 1.52
Net income available to common unitholders per unit - diluted (in dollars per unit)	$ 1.86	$ 2.55	$ 1.51
Weighted average common units outstanding - basic (in shares)	105,223,975	102,025,276	100,246,567
Weighted average common units outstanding - diluted (in shares)	105,872,575	102,535,282	100,860,337
Kilroy Realty L.P. [Member] | Rental income [Member]
REVENUES (Note 2):
Revenues	$ 826,472	$ 656,631	$ 633,896
Kilroy Realty L.P. [Member] | Tenant reimbursements [Member]
REVENUES (Note 2):
Revenues	0	80,982	76,559
Kilroy Realty L.P. [Member] | Other property income [Member]
REVENUES (Note 2):
Revenues	10,982	9,685	8,546
Kilroy Realty L.P. [Member] | Property [Member]
EXPENSES:
Property expenses (Note 2)	$ 160,037	$ 133,787	$ 129,971

CONSOLIDATED STATEMENTS OF CAPI

CONSOLIDATED STATEMENTS OF CAPITAL (KILROY REALTY, L.P.) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 77,922	$ 41,794	$ 166,890	$ 40,971	$ 215,229	$ 277,926	$ 180,615
Redemption of Series G & H Preferred stock							(200,000)
Non-cash amortization of share-based compensation					32,813	35,890	26,319
Settlement of restricted stock units					0	0	0
Distributions to noncontrolling interests in consolidated property partnerships					(12,952)	(11,803)	(16,542)
Preferred dividends and distributions							(5,774)
Accounting Standards Update 2016-02 [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Opening adjustment to Partners’ Capital upon adoption of ASC 842 (Note 2)								$ (3,146)
Noncontrolling Interest In Consolidated Subsidiaries [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income					19,786	19,511	16,003
Distributions to noncontrolling interests in consolidated property partnerships					(12,952)	(11,803)	(16,542)
Kilroy Realty L.P. [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		4,201,261		3,960,316	4,201,261	3,960,316	3,759,317
Net income	77,922	41,794	166,890	40,971	215,229	277,926	180,615
Redemption of Series G & H Preferred stock							(200,000)
Issuance of common units					353,722	130,693	326,058
Issuance of share-based compensation awards					4,664	3,926	5,890
Non-cash amortization of share-based compensation					32,813	35,890	26,319
Exercise of stock options					703	41	12,179
Settlement of restricted stock units					0	0	0
Repurchase of common units and restricted stock units					(14,861)	(16,553)	(12,986)
Contributions from noncontrolling interest in consolidated property partnership						8,273	54,604
Distributions to noncontrolling interests in consolidated property partnerships					(12,952)	(11,803)	(16,542)
Preferred dividends and distributions							(5,774)
Distributions declared per common unit					(206,575)	(187,448)	(169,364)
Ending balance	4,570,858		4,201,261		4,570,858	4,201,261	3,960,316
Kilroy Realty L.P. [Member] | Accounting Standards Update 2016-02 [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Opening adjustment to Partners’ Capital upon adoption of ASC 842 (Note 2)								(3,146)
Kilroy Realty L.P. [Member] | Total Partners Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		4,003,700		3,773,941	4,003,700	3,773,941	3,624,179
Net income					198,738	263,210	167,440
Redemption of Series G & H Preferred stock							(200,000)
Issuance of common units					353,722	130,693	326,058
Issuance of share-based compensation awards					4,664	3,926	5,890
Non-cash amortization of share-based compensation					32,813	35,890	26,319
Exercise of stock options					703	41	12,179
Repurchase of common units and restricted stock units					(14,861)	(16,553)	(12,986)
Preferred dividends and distributions							(5,774)
Distributions declared per common unit					(206,575)	(187,448)	(169,364)
Ending balance	4,369,758		4,003,700		4,369,758	4,003,700	3,773,941
Kilroy Realty L.P. [Member] | Total Partners Capital [Member] | Accounting Standards Update 2016-02 [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Opening adjustment to Partners’ Capital upon adoption of ASC 842 (Note 2)								(3,146)
Kilroy Realty L.P. [Member] | Partners Capital Preferred Units [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		0		0	0	0	192,411
Redemption of Series G & H Preferred stock							(192,411)
Ending balance	0		0		0	0	0
Kilroy Realty L.P. [Member] | Partners Capital Common Unit [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ 4,003,700		$ 3,773,941	$ 4,003,700	$ 3,773,941	$ 3,431,768
Beginning balance (in units)		102,772,275		100,697,526	102,772,275	100,697,526	95,600,982
Net income					$ 198,738	$ 263,210	$ 167,440
Redemption of Series G & H Preferred stock							(7,589)
Issuance of common units					$ 353,722	$ 130,693	$ 326,058
Issuance of common units (in units)					5,000,000	1,817,195	4,662,577
Issuance of share-based compensation awards					$ 4,664	$ 3,926	$ 5,890
Non-cash amortization of share-based compensation					32,813	35,890	26,319
Exercise of stock options					$ 703	$ 41	$ 12,179
Exercise of stock options (in units)					16,500	1,000	285,000
Settlement of restricted stock units (in units)					463,276	488,354	317,848
Repurchase of common units and restricted stock units					$ (14,861)	$ (16,553)	$ (12,986)
Repurchase of common units and restricted stock units (in units)					(212,477)	(231,800)	(168,881)
Preferred dividends and distributions							$ (5,774)
Distributions declared per common unit					$ (206,575)	$ (187,448)	(169,364)
Ending balance	$ 4,369,758		$ 4,003,700		$ 4,369,758	$ 4,003,700	$ 3,773,941
Ending balance (in units)	108,039,574		102,772,275		108,039,574	102,772,275	100,697,526
Kilroy Realty L.P. [Member] | Partners Capital Common Unit [Member] | Accounting Standards Update 2016-02 [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Opening adjustment to Partners’ Capital upon adoption of ASC 842 (Note 2)								$ (3,146)
Kilroy Realty L.P. [Member] | Noncontrolling Interest In Consolidated Subsidiaries [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance		$ 197,561		$ 186,375	$ 197,561	$ 186,375	$ 135,138
Net income					16,491	14,716	13,175
Contributions from noncontrolling interest in consolidated property partnership						8,273	54,604
Distributions to noncontrolling interests in consolidated property partnerships					(12,952)	(11,803)	(16,542)
Ending balance	$ 201,100		$ 197,561		$ 201,100	$ 197,561	$ 186,375

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CAPITAL (KILROY REALTY, L.P.) - Parenthetical - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Kilroy Realty L.P. [Member]
Distributions declared per common unit (in dollars per units)	$ 1.91000	$ 1.79000	$ 1.650

CONSOLIDATED STATEMENTS OF CA_3

CONSOLIDATED STATEMENTS OF CASH FLOWS (KILROY REALTY, L.P.) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 215,229	$ 277,926	$ 180,615
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of real estate assets and leasing costs	268,045	249,882	241,862
Depreciation of non-real estate furniture, fixtures and equipment	5,085	4,400	4,024
(Recoveries of) provision for bad debts (Notes 2 and 20)	(3,433)	5,685	3,269
Non-cash amortization of share-based compensation awards (Note 15)	27,007	27,932	19,046
Non-cash amortization of deferred financing costs and net debt discounts	1,427	1,084	3,247
Non-cash amortization of net below market rents (Note 5)	(9,206)	(9,748)	(8,528)
Gains on sales of depreciable operating properties (Note 4)	(36,802)	(142,926)	(39,507)
Non-cash amortization of deferred revenue related to tenant-funded tenant improvements (Note 10)	(19,190)	(18,429)	(16,767)
Straight-line rents	(72,023)	(26,976)	(33,275)
Amortization of right of use ground lease assets (Note 2)	683
Loss on early extinguishment of debt (Note 9)	0	12,623	5,312
(Gain) loss on sale of land (Note 4)	0	(11,825)	(449)
Net change in other operating assets	(14,476)	(7,930)	(17,732)
Net change in other operating liabilities	24,175	48,345	5,895
Net cash provided by operating activities	386,521	410,043	347,012
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for development properties and undeveloped land	(845,464)	(489,236)	(397,440)
Expenditures for acquisitions of development properties and undeveloped land (Note 3)	(173,291)	(311,299)	(19,829)
Expenditures for acquisitions of operating properties (Note 3)	(186,258)	(257,340)	0
Expenditures for operating properties and other capital assets	(147,687)	(166,440)	(88,425)
Net proceeds received from dispositions (Note 4)	124,421	364,300	182,492
Decrease (increase) in acquisition-related deposits			(35,900)
Decrease (increase) in acquisition-related deposits	0	36,000
Proceeds received from repayment of note receivable	0	15,100	0
Net cash used in investing activities	(1,228,279)	(808,915)	(359,102)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common units (Note 14)	353,722	130,693	326,058
Redemption of Series G and H Preferred units (Note 14)	0	0	(200,000)
Net proceeds from the issuance of unsecured debt (Note 9)	499,390	648,537	674,447
Repayments of unsecured debt (Note 9)	0	(261,823)	(519,024)
Borrowings on unsecured revolving credit facility	1,110,000	765,000	270,000
Repayments on unsecured revolving credit facility	(910,000)	(690,000)	(270,000)
Borrowings on unsecured debt (Note 9)	0	120,000	0
Principal payments and repayments of secured debt (Note 9)	(76,309)	(3,584)	(130,371)
Financing costs	(6,678)	(6,262)	(11,500)
Repurchase of common units and restricted stock units (Note 15)	(14,556)	(16,553)	(12,986)
Proceeds from exercise of stock options	703	41	12,179
Contributions from noncontrolling interests in consolidated property partnerships (Note 12)	0	8,273	54,604
Distributions to noncontrolling interests in consolidated property partnerships	(12,952)	(11,803)	(16,542)
Distributions paid to common unitholders	(196,252)	(179,411)	(340,697)
Distributions paid to preferred unitholders	0	0	(7,409)
Net cash provided by (used in) financing activities	747,068	503,108	(171,241)
Net (decrease) increase in cash and cash equivalents and restricted cash	(94,690)	104,236	(183,331)
Cash and cash equivalents and restricted cash, beginning of year	171,034	66,798	250,129
Cash and cash equivalents and restricted cash, end of year	76,344	171,034	66,798
Kilroy Realty L.P. [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	215,229	277,926	180,615
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of real estate assets and leasing costs	268,045	249,882	241,862
Depreciation of non-real estate furniture, fixtures and equipment	5,085	4,400	4,024
(Recoveries of) provision for bad debts (Notes 2 and 20)	(3,433)	5,685	3,269
Non-cash amortization of share-based compensation awards (Note 15)	27,007	27,932	19,046
Non-cash amortization of deferred financing costs and net debt discounts	1,427	1,084	3,247
Non-cash amortization of net below market rents (Note 5)	(9,206)	(9,748)	(8,528)
Gains on sales of depreciable operating properties (Note 4)	(36,802)	(142,926)	(39,507)
Non-cash amortization of deferred revenue related to tenant-funded tenant improvements (Note 10)	(19,190)	(18,429)	(16,767)
Straight-line rents	(72,023)	(26,976)	(33,275)
Amortization of right of use ground lease assets (Note 2)	683
Loss on early extinguishment of debt (Note 9)	0	12,623	5,312
(Gain) loss on sale of land (Note 4)	0	(11,825)	(449)
Net change in other operating assets	(14,476)	(7,930)	(17,732)
Net change in other operating liabilities	24,175	48,345	5,895
Net cash provided by operating activities	386,521	410,043	347,012
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for development properties and undeveloped land	(845,464)	(489,236)	(397,440)
Expenditures for acquisitions of development properties and undeveloped land (Note 3)	(173,291)	(311,299)	(19,829)
Expenditures for acquisitions of operating properties (Note 3)	(186,258)	(257,340)	0
Expenditures for operating properties and other capital assets	(147,687)	(166,440)	(88,425)
Net proceeds received from dispositions (Note 4)	124,421	364,300	182,492
Decrease (increase) in acquisition-related deposits	0		(35,900)
Decrease (increase) in acquisition-related deposits		36,000
Proceeds received from repayment of note receivable	0	15,100	0
Net cash used in investing activities	(1,228,279)	(808,915)	(359,102)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common units (Note 14)	353,722	130,693	326,058
Redemption of Series G and H Preferred units (Note 14)	0	0	(200,000)
Net proceeds from the issuance of unsecured debt (Note 9)	499,390	648,537	674,447
Repayments of unsecured debt (Note 9)	0	(261,823)	(519,024)
Borrowings on unsecured revolving credit facility	1,110,000	765,000	270,000
Repayments on unsecured revolving credit facility	(910,000)	(690,000)	(270,000)
Borrowings on unsecured debt (Note 9)	0	120,000	0
Principal payments and repayments of secured debt (Note 9)	(76,309)	(3,584)	(130,371)
Financing costs	(6,678)	(6,262)	(11,500)
Repurchase of common units and restricted stock units (Note 15)	(14,556)	(16,553)	(12,986)
Proceeds from exercise of stock options	703	41	12,179
Contributions from noncontrolling interests in consolidated property partnerships (Note 12)	0	8,273	54,604
Distributions to noncontrolling interests in consolidated property partnerships	(12,952)	(11,803)	(16,542)
Distributions paid to common unitholders	(196,252)	(179,411)	(340,697)
Distributions paid to preferred unitholders	0	0	(7,409)
Net cash provided by (used in) financing activities	747,068	503,108	(171,241)
Net (decrease) increase in cash and cash equivalents and restricted cash	(94,690)	104,236	(183,331)
Cash and cash equivalents and restricted cash, beginning of year	171,034	66,798	250,129
Cash and cash equivalents and restricted cash, end of year	$ 76,344	$ 171,034	$ 66,798

Organization and Ownership

Organization and Ownership	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Ownership	Organization and Ownership Kilroy Realty Corporation (the “Company”) is a self-administered real estate investment trust (“REIT”) active in premier office and mixed-use submarkets along the West Coast. We own, develop, acquire and manage real estate assets, consisting primarily of Class A properties in the coastal regions of Greater Los Angeles, San Diego County, the San Francisco Bay Area and Greater Seattle, which we believe have strategic advantages and strong barriers to entry. Class A real estate encompasses attractive and efficient buildings of high quality that are attractive to tenants, are well-designed and constructed with above-average material, workmanship and finishes and are well-maintained and managed. We qualify as a REIT under the Internal Revenue Code of 1986, as amended (the “Code”). The Company’s common stock is publicly traded on the New York Stock Exchange (“NYSE”) under the ticker symbol “KRC.” We own our interests in all of our real estate assets through Kilroy Realty, L.P. (the “Operating Partnership”) and Kilroy Realty Finance Partnership, L.P. (the “Finance Partnership”). We generally conduct substantially all of our operations through the Operating Partnership. Unless stated otherwise or the context indicates otherwise, the terms “Kilroy Realty Corporation” or the “Company,” “we,” “our,” and “us” refer to Kilroy Realty Corporation and its consolidated subsidiaries and the term “Operating Partnership” refers to Kilroy Realty, L.P. and its consolidated subsidiaries. The descriptions of our business, employees, and properties apply to both the Company and the Operating Partnership. Our stabilized portfolio of operating properties was comprised of the following properties at December 31, 2019 : Number of Buildings Rentable Square Feet (unaudited) Number of Tenants Percentage Occupied (unaudited) Percentage Leased (unaudited) Stabilized Office Properties 112 13,475,795 451 94.6 % 97.0 % Number of Number of Units 2019 Average Occupancy Stabilized Residential Property 1 200 82.4 % Our stabilized portfolio includes all of our properties with the exception of development and redevelopment properties currently committed for construction, under construction, or in the tenant improvement phase, undeveloped land, recently completed residential properties not yet stabilized and real estate assets held for sale. We define redevelopment properties as those properties for which we expect to spend significant development and construction costs on the existing or acquired buildings pursuant to a formal plan, the intended result of which is a higher economic return on the property. We define properties in the tenant improvement phase as office and retail properties that we are developing or redeveloping where the project has reached cold shell condition and is ready for tenant improvements, which may require additional major base building construction before being placed in service. Projects in the tenant improvement phase are added to our stabilized portfolio once the project reaches the earlier of 95% occupancy or one year from the date of the cessation of major base building construction activities. Costs capitalized to construction in progress for development and redevelopment properties are transferred to land and improvements, buildings and improvements, and deferred leasing costs on our consolidated balance sheets at the historical cost of the property as the projects are placed in service. During the year ended December 31, 2019 , we added one completed development project to our stabilized office portfolio consisting of 394,340 square feet in San Francisco, California. As of December 31, 2019 , the following properties were excluded from our stabilized portfolio. We did not have any redevelopment properties or properties held for sale at December 31, 2019 . Number of Properties/Projects Estimated Rentable Square Feet (1) / Units (unaudited) In-process development projects - tenant improvement (2) 2 846,000 In-process development projects - under construction (3) 6 2,291,000 Completed residential development project (4) 1 237 units _______________ (1) Estimated rentable square feet upon completion. (2) Includes 96,000 square feet of retail space. (3) In addition to the estimated office and life science rentable square feet noted above, development projects under construction also include 564 residential units. (4) Represents recently completed residential units not yet stabilized. Our stabilized portfolio also excludes our future development pipeline, which as of December 31, 2019 was comprised of five future development sites, representing approximately 61 gross acres of undeveloped land. As of December 31, 2019 , all of our properties and development projects were owned and all of our business was conducted in the state of California with the exception of eight office properties, one development project under construction and one recently acquired future development project located in the state of Washington. All of our properties and development projects are 100% owned, excluding four office properties owned by three consolidated property partnerships and two development projects held by consolidated variable interest entities established to facilitate potential transactions intended to qualify as like-kind exchanges pursuant to Section 1031 of the Code (“Section 1031 Exchange”). Two of the three consolidated property partnerships, 100 First Street Member, LLC (“100 First LLC”) and 303 Second Street Member, LLC (“303 Second LLC”), each owned one office property in San Francisco, California through subsidiary REITs. As of December 31, 2019 , the Company owned a 56% common equity interest in both 100 First LLC and 303 Second LLC. The third consolidated property partnership, Redwood City Partners, LLC (“Redwood LLC”) owned two office properties in Redwood City, California. As of December 31, 2019 , the Company owned an approximate 93% common equity interest in Redwood LLC. The remaining interests in all three property partnerships were owned by unrelated third parties. As of December 31, 2019 , the Company owned an approximate 98.1% common general partnership interest in the Operating Partnership. The remaining approximate 1.9% common limited partnership interest in the Operating Partnership as of December 31, 2019 was owned by non-affiliated investors and certain of our executive officers and directors. Both the general and limited common partnership interests in the Operating Partnership are denominated in common units. Generally, the number of common units held by the Company is equivalent to the number of outstanding shares of the Company’s common stock, and the rights of all the common units to quarterly distributions and payments in liquidation mirror those of the Company’s common stockholders. The common limited partners have certain redemption rights as provided in the Operating Partnership’s Seventh Amended and Restated Agreement of Limited Partnership, as amended, the “Partnership Agreement”. Kilroy Realty Finance, Inc., which is a wholly-owned subsidiary of the Company, is the sole general partner of the Finance Partnership and owns a 1.0% common general partnership interest in the Finance Partnership. The Operating Partnership owns the remaining 99.0% common limited partnership interest. With the exception of the Operating Partnership and our consolidated property partnerships, all of our subsidiaries are wholly-owned.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Basis of Presentation and Significant Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	Basis of Presentation and Significant Accounting Policies Basis of Presentation The consolidated financial statements of the Company include the consolidated financial position and results of operations of the Company, the Operating Partnership, the Finance Partnership, 303 Second LLC, 100 First LLC, Redwood LLC and all of our wholly-owned and controlled subsidiaries. The consolidated financial statements of the Operating Partnership include the consolidated financial position and results of operations of the Operating Partnership, the Finance Partnership, 303 Second LLC, 100 First LLC, Redwood LLC and all of our wholly-owned and controlled subsidiaries. All intercompany balances and transactions have been eliminated in the consolidated financial statements. Partially Owned Entities and Variable Interest Entities At December 31, 2019 the consolidated financial statements of the Company included four VIEs in addition to the Operating Partnership: two of the consolidated property partnerships, 100 First LLC, 303 Second LLC, and two entities established during the fourth quarter of 2019 to facilitate potential future Section 1031 Exchanges. At December 31, 2019 , the Company and the Operating Partnership were determined to be the primary beneficiaries of these four VIEs since we had the ability to control the activities that most significantly impact each of the VIEs’ economic performance. As of December 31, 2019 , the four VIEs’ total assets, liabilities and noncontrolling interests included on our consolidated balance sheet were approximately $676.7 million (of which $598.0 million related to real estate held for investment), approximately $40.1 million and approximately $189.6 million , respectively. Revenues, income and net assets generated by 100 First LLC and 303 Second LLC may only be used to settle their contractual obligations, which primarily consist of operating expenses, capital expenditures and required distributions. At December 31, 2018 , the consolidated financial statements of the Company included three VIEs in addition to the Operating Partnership: two of the consolidated property partnerships, 100 First LLC and 303 Second LLC, and an entity established during the fourth quarter of 2018 to facilitate a Section 1031 Exchange. At December 31, 2018 , the Company and the Operating Partnership were determined to be the primary beneficiaries of these three VIEs since we had the ability to control the activities that most significantly impact each of the VIEs’ economic performance. At December 31, 2018 , the three VIEs’ total assets, liabilities and noncontrolling interests included on our consolidated balance sheet were approximately $615.4 million (of which $543.9 million related to real estate held for investment on our consolidated balance sheet), approximately $45.1 million and approximately $186.4 million , respectively. In January 2019, the Section 1031 Exchange was successfully completed and the related VIE was terminated. Our accounting policy is to consolidate entities in which we have a controlling financial interest and significant decision making control over the entity's operations. In determining whether we have a controlling financial interest in a partially owned entity and the requirement to consolidate the accounts of that entity, we consider factors such as ownership interest, board representation, management representation, size of our investment (including loans), authority to control decisions, and contractual and substantive participating rights of the members. In addition to evaluating control rights, we consolidate entities in which the other members have no substantive kick-out rights to remove the Company as the managing member. Entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or the holders of the equity investment at risk do not have a controlling financial interest are VIEs. We evaluate whether an entity is a VIE and whether we are the primary beneficiary. We are deemed to be the primary beneficiary of a VIE when we have the power to direct the activities of the VIE that most significantly impact the VIEs’ economic performance and the obligation to absorb losses or receive benefits that could potentially be significant to the VIE. If the requirements for consolidation are not met, the Company would account for investments under the equity method of accounting if we have the ability to exercise significant influence over the entity. Equity method investments would be initially recorded at cost and subsequently adjusted for our share of net income or loss and cash contributions and distributions each period. The Company did not have any equity method investments at December 31, 2019 or 2018 . Accounting Pronouncements Adopted January 1, 2019 Effective January 1, 2019, we adopted Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2016-02 “Leases (Topic 842)” (“Topic 842”) and the related FASB ASU Nos. 2018-01, 2018-10, 2018-11, 2018-20 and 2019-01 which provide practical expedients, technical corrections and improvements for certain aspects of ASU 2016-02, on a modified retrospective basis. Topic 842 establishes a single comprehensive model for entities to use in accounting for leases and supersedes the existing leasing guidance. We evaluated each of the Company’s contracts to determine if the contract is or contains a lease and concluded that Topic 842 is applicable to the Company as a lessor in its tenant lease agreements and as a lessee in its ground leases. Lessor Accounting As a lessor, the Company’s leases with tenants for its real estate assets generally provide for the lease of space, as well as common area maintenance and parking. Under Topic 842, the lease of space is considered a lease component while the common area maintenance billings and tenant parking are considered nonlease components, which fall under revenue recognition guidance in FASB Accounting Standards Codification Topic 606 “Revenue from Contracts with Customers” (“Topic 606”). However, upon adopting the guidance in Topic 842, the Company determined that its tenant leases met the criteria to apply the practical expedient provided by ASU 2018-11 to recognize the lease and non-lease components together as one single component. This conclusion was based on the consideration that 1) the timing and pattern of transfer of the nonlease components and associated lease component are the same, and 2) the lease component, if accounted for separately, would be classified as an operating lease. As the lease of space is the predominant component of the Company’s leasing arrangements, we accounted for all lease and non-lease components as one single component under Topic 842. As a result, the adoption of Topic 842 did not have any impact on the Company’s timing or pattern of recognition of rental revenues as compared to previous guidance. Transient daily parking revenue is accounted for under the guidance in Topic 606 and included in other property income in our consolidated statements of operations. To reflect their recognition as one lease component, base rental revenues, additional rental revenues (which consist of amounts due from tenants for common area maintenance, real estate taxes, and other recoverable costs) and other lease related property income related to leases that also meet the requirements of the practical expedient provided by ASU 2018-11 have been combined in one line item subsequent to the adoption of Topic 842 for the year ended December 31, 2019 in rental income on the Company’s consolidated statements of operations. In addition, under Topic 842, lessor costs for certain services directly reimbursed by tenants, which were previously presented on a net basis under previous guidance, are required to be presented on a gross basis in revenues and expenses. During the year ended December 31, 2019 , we incurred additional property expenses of $13.9 million for which we were reimbursed, that were not required to be grossed up under the previous guidance. We presented this amount on a gross basis within rental income and property expenses in the Company’s consolidated statements of operations as a result of the adoption, which had no impact on net income. Our rental income is mostly comprised of fixed contractual payments defined under the lease that, in most cases, escalate annually over the term of the lease at fixed rates. Additionally, rental income includes variable payments for tenant reimbursements of property-related expenses and payments based on a percentage of tenant’s sales. The table below sets forth the allocation of rental income between fixed and variable payments for the year ended December 31, 2019 : Year Ended December 31, 2019 (in thousands) Fixed lease payments $ 710,557 Variable lease payments 115,915 Total rental income $ 826,472 Upon the adoption of Topic 842 on January 1, 2019, the method for recognizing revenue includes a binary assessment of whether or not substantially all of the amounts due under a tenant’s lease agreement are probable of collection. For leases that are deemed probable of collection, revenue is recorded on a straight-line basis over the lease term. For leases that are deemed not probable of collection, revenue is recorded as the lesser of (i) the amount which would be recognized on a straight-line basis or (ii) cash that has been received from the tenant, with any tenant and deferred rent receivable balances charged as a direct write-off against rental income in the period of the change in the collectability determination. Refer to our Significant Accounting Policies below for further discussion of our revenue recognition and allowance for uncollectible tenant and deferred rent receivables policies. Leasing Costs Upon adoption of Topic 842, the Company elected to apply the package of practical expedients provided and did not reassess the following as of January 1, 2019: 1) whether any expired or existing contracts are or contain leases; 2) the lease classification for any expired or existing leases; and 3) initial direct costs for any existing leases. Under Topic 842, initial direct costs for both lessees and lessors would include only those costs that are incremental to the arrangement and would not have been incurred if the lease had not been obtained. As a result, beginning January 1, 2019, the Company no longer capitalized internal leasing costs and third-party legal leasing costs and instead expensed these costs as incurred. These expenses are included in leasing costs and general and administrative expenses on our consolidated statements of operations in 2019. During the year ended December 31, 2019 , the Company expensed approximately $11.4 million of indirect leasing costs which would have been capitalized prior to the adoption of Topic 842. The election of the package of practical expedients described above permits us to continue to account for our leases that commenced before January 1, 2019 under the previously existing lease accounting guidance for the remainder of their lease terms, and to apply the new lease accounting guidance to leases commencing or modified after January 1, 2019. On January 1, 2019, we recognized a $3.1 million cumulative-effect adjustment, primarily related to internal leasing costs and legal leasing costs for tenant leases that had not commenced prior to that date, to increase distributions in excess of earnings for the Company and partners’ capital for the Operating Partnership in connection with our adoption of Topic 842. Lessee Accounting The Company’s ground leases are the primary contracts in which we are the lessee. Upon adoption of Topic 842 on January 1, 2019, the Company had four existing ground leases which were classified as operating leases. As discussed above, the Company elected to apply the package of practical expedients provided by Topic 842 and therefore did not reassess the classification of these ground leases. Existing ground leases that commenced before the January 1, 2019 adoption date continued to be accounted for as operating leases, and the new guidance did not have a material impact on our recognition of ground lease expense or our results of operations. However, for periods beginning after January 1, 2019, we are now required to recognize a lease liability on our consolidated balance sheets equal to the present value of the minimum future lease payments required in accordance with each ground lease, as well as a right of use asset equal to the lease liability adjusted for above and below market intangibles and deferred leasing costs. To determine the discount rates used to calculate the present value of the lease payments, we used a hypothetical curve derived from unsecured corporate borrowing rates over the lease terms. The weighted average discount rate for our four existing ground leases was 5.15% . The adoption of Topic 842 resulted in the recognition of right of use ground lease assets totaling $82.9 million and ground lease liabilities totaling $87.4 million on January 1, 2019. There was no material impact to our consolidated statements of operations or consolidated statements of cash flows as a result of adoption of this new guidance. For further information related to our ground leases, refer to Note 18 “Commitments and Contingencies.” For leases with a term of 12 months or less where we are the lessee, we made an accounting policy election by class of underlying asset not to recognize right of use lease assets and lease liabilities. We recognize lease expense for such leases generally on a straight-line basis over the lease term. Significant Accounting Policies Revenue Recognition Rental revenue for office and retail operating properties is our principal source of revenue. We recognize revenue from base rent, additional rent (which consists of amounts due from tenants for common area maintenance, real estate taxes, and other recoverable costs), parking and other lease-related revenue once all of the following criteria are met: (i) the agreement has been fully executed and delivered, (ii) services have been rendered, (iii) the amount is fixed or determinable and (iv) payment has been received or the collectability of the amount due is probable. Lease termination fees are amortized over the remaining lease term, if applicable. If there is no remaining lease term, they are recognized when received and realized. Minimum annual rental revenues are recognized in rental revenues on a straight-line basis over the non-cancellable term of the related lease. Base Rent The timing of when we commence rental revenue recognition for office and retail properties depends largely on our conclusion as to whether the Company or the tenant is the owner for accounting purposes of tenant improvements at the leased property. When we conclude that we are the owner of tenant improvements for accounting purposes, we record the cost to construct the tenant improvements as an asset and commence rental revenue recognition when the tenant takes possession of or controls the finished space, which is generally when tenant improvements being recorded as our assets are substantially complete. In certain instances, when we conclude that the tenant is the owner of certain tenant improvements for accounting purposes, rental revenue recognition begins when the tenant takes possession or controls the physical use of the leased space, which may occur in phases or for an entire building or project. The determination of who owns the tenant improvements is made on a lease-by-lease basis and has a significant effect on the timing of commencement of revenue recognition. When we conclude that the Company is the owner of tenant improvements for accounting purposes, we record the cost to construct the tenant improvements, including costs paid for or reimbursed by the tenants, as a capital asset. For these tenant-funded tenant improvements, we record the amount funded by or reimbursed by tenants as deferred revenue, which is amortized and recognized as rental income on a straight-line basis over the term of the related lease. When we conclude that the tenant is the owner of certain tenant improvements for accounting purposes, we record our contribution towards those tenant-owned improvements as a lease incentive, which is included in deferred leasing costs and acquisition-related intangible assets, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the related lease. For residential properties, we commence revenue recognition upon lease commencement. Residential rental revenue is recognized on a straight-line basis over the term of the related lease, net of any concessions. Additional Rent - Reimbursements from Tenants Additional rent, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized in rental income in the period the recoverable costs are incurred. Prior to the adoption of Topic 842, such amounts were recognized in revenue as tenant reimbursements. Additional rent where we pay the associated costs directly to third-party vendors and are reimbursed by our tenants are recognized and recorded on a gross basis, with the corresponding expense recognized in property expenses or real estate taxes. Prior to the adoption of Topic 842, recoverable costs were generally recognized and recorded on a gross basis when we were the primary obligor with respect to purchasing goods and services from third-party suppliers, had discretion in selecting the supplier, and had credit risk. Other Property Income Other property income primarily includes amounts recorded in connection with transient daily parking, tenant bankruptcy settlement payments, broken deal income and property damage settlement related payments. Other property income also includes miscellaneous income from tenants, restoration fees and fees for late rental payments. Amounts recorded within other property income fall within the scope of Topic 606 and are recognized as revenue at the point in time when control of the goods or services transfers to the customer and our performance obligation is satisfied. Uncollectible Lease Receivables and Allowances for Tenant and Deferred Rent Receivables We carry our current and deferred rent receivables net of allowances for amounts that may not be collected. Prior to the adoption of Topic 842 on January 1, 2019, the allowances were increased or decreased through provision for bad debts on our consolidated statements of operations. Upon the adoption of Topic 842 on January 1, 2019, the allowances are increased or decreased through rental income, and our determination of the adequacy of the Company’s allowances for tenant receivables includes a binary assessment of whether or not substantially all of the amounts due under a tenant’s lease agreement are probable of collection. Such assessment involves using a methodology that incorporates a specific identification analysis and an aging analysis and considers the current economic and business environment. This determination requires significant judgment and estimates about matters that are uncertain at the time the estimates are made, including the creditworthiness of specific tenants, specific industry trends and conditions, and general economic trends and conditions. For leases that are deemed probable of collection, revenue continues to be recorded on a straight-line basis over the lease term. For leases that are deemed not probable of collection, revenue is recorded as the lesser of (i) the amount which would be recognized on a straight-line basis or (ii) cash that has been received from the tenant, with any tenant and deferred rent receivable balances charged as a direct write-off against rental income in the period of the change in the collectability determination. For tenant and deferred rent receivables associated with leases whose rents are deemed probable of collection under Topic 842, we may record an allowance under other authoritative GAAP using a methodology that incorporates a specific identification analysis and an aging analysis and considers the current economic and business environment. This determination requires significant judgment and estimates about matters that are uncertain at the time the estimates are made, including the creditworthiness of specific tenants, specific industry trends and conditions, and general economic trends and conditions. Tenant and deferred rent receivables deemed probable of collection are carried net of allowances for uncollectible accounts, with increases or decreases in the allowances recorded through rental income on our consolidated statements of operations. Prior to the adoption of Topic 842 on January 1, 2019, the allowances were increased or decreased through provision for bad debts on our consolidated statements of operations. Current tenant receivables consist primarily of amounts due for contractual lease payments and reimbursements of common area maintenance expenses, property taxes, and other costs recoverable from tenants. With respect to the allowance for uncollectible tenant receivables, the specific identification methodology analysis relies on factors such as the age and nature of the receivables, the payment history and financial condition of the tenant, our assessment of the tenant’s ability to meet its lease obligations, and the status of negotiations of any disputes with the tenant. Deferred rent receivables represent the amount by which the cumulative straight-line rental revenue recorded to date exceeds cash rents billed to date under the lease agreement. With respect to the allowance for deferred rent receivables, given the longer-term nature of these receivables, the specific identification methodology analysis evaluates each of our significant tenants and any tenants on our internal watchlist and relies on factors such as each tenant’s financial condition and its ability to meet its lease obligations. We evaluate our reserve levels quarterly based on changes in the financial condition of tenants and our assessment of the tenant’s ability to meet its lease obligations, overall economic conditions, and the current business environment. Acquisitions Acquisitions of operating properties and development and redevelopment opportunities generally do not meet the definition of a business and are accounted for as asset acquisitions, as substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. For these asset acquisitions, we record the acquired tangible and intangible assets and assumed liabilities based on each asset’s and liability’s relative fair value at the acquisition date of the total purchase price plus any capitalized acquisition costs. We record the acquired tangible and intangible assets and assumed liabilities of acquisitions of operating properties and development and redevelopment opportunities that meet the accounting criteria to be accounted for as business combinations at fair value at the acquisition date. Transaction costs associated with asset acquisitions are capitalized as part of the purchase price of the acquisition. The acquired assets and assumed liabilities for an acquisition generally include but are not limited to (i) land and improvements, buildings and improvements, undeveloped land and construction in progress and (ii) identified tangible and intangible assets and liabilities associated with in-place leases, including tenant improvements, leasing costs, value of above-market and below-market operating leases and ground leases, acquired in-place lease values and tenant relationships, if any. Any debt assumed and equity (including common units of the Operating Partnership) issued in connection with a property acquisition is recorded at fair value on the date of acquisition. The fair value of land and improvements is derived from comparable sales of land and improvements within the same submarket and/or region. The fair value of buildings and improvements, tenant improvements and leasing costs considers the value of the property as if it was vacant as well as current replacement costs and other relevant market rate information. The fair value of the above-market or below-market component of an acquired in-place operating lease is based upon the present value (calculated using a market discount rate) of the difference between (i) the contractual rents to be paid pursuant to the lease over its remaining non-cancellable lease term and (ii) our estimate of the rents that would be paid using fair market rental rates and rent escalations at the date of acquisition measured over the remaining non-cancellable term of the lease for above-market operating leases and the initial non-cancellable term plus the term of any below-market fixed rate renewal options, if applicable, for below-market operating leases. Our below-market operating leases generally do not include fixed rate or below-market renewal options. The amounts recorded for above-market operating leases are included in deferred leasing costs and acquisition-related intangible assets, net on the balance sheet and are amortized on a straight-line basis as a reduction of rental income over the remaining term of the applicable leases. The amounts recorded for below-market operating leases are included in deferred revenue and acquisition-related intangible liabilities, net on the balance sheet and are amortized on a straight-line basis as an increase to rental income over the remaining term of the applicable leases plus the term of any below-market fixed rate renewal options, if applicable. The amortization of a below-market ground lease obligation is recorded as an increase to ground lease expense in the consolidated statements of operations for the periods presented. The amortization of an above-market ground lease obligation is recorded as a decrease to ground lease expense in the consolidated statements of operations for the periods presented. The fair value of acquired in-place leases is derived based on our assessment of lost revenue and costs incurred for the period required to lease the “assumed vacant” property to the occupancy level when purchased. The amount recorded for acquired in-place leases is included in deferred leasing costs and acquisition-related intangible assets, net on the balance sheet and amortized as an increase to depreciation and amortization expense over the remaining term of the applicable leases. Fully amortized intangible assets are written off each quarter. Operating Properties Operating properties are generally carried at historical cost less accumulated depreciation. Properties held for sale are reported at the lower of the carrying value or the fair value less estimated cost to sell. The cost of operating properties includes the purchase price or development costs of the properties. Costs incurred for the renovation and betterment of the operating properties are capitalized to our investment in that property. Maintenance and repairs are charged to expense as incurred. When evaluating properties to be held and used for potential impairment, we first evaluate whether there are any indicators of impairment for any of our properties. If any impairment indicators are present for a specific property, we then evaluate the regional market conditions that could reasonably affect the property. If there are negative changes and trends in that regional market, we then perform an undiscounted cash flow analysis and compare the net carrying amount of the property to the property’s estimated undiscounted future cash flow over the anticipated holding period. If the estimated undiscounted future cash flow is less than the net carrying amount of the property, we perform an impairment loss calculation to determine if the fair value of the property is less than the net carrying value of the property. Our impairment loss calculation compares the net carrying amount of the property to the property’s estimated fair value, which may be based on estimated discounted future cash flow calculations or third-party valuations or appraisals. We would recognize an impairment loss if the property's net carrying amount exceeds the property's estimated fair value. If we were to recognize an impairment loss, the estimated fair value of the property becomes its new cost basis. For a depreciable long-lived asset, the new cost basis would be depreciated (amortized) over the remaining useful life of that asset. Cost Capitalization All costs clearly associated with the development, redevelopment and construction of a property are capitalized as project costs, including internal compensation costs. In addition, the following costs are capitalized as project costs during periods in which activities necessary to prepare development and redevelopment properties for their intended use are in progress: pre-construction costs essential to the development of the property, interest, real estate taxes and insurance. • For office and retail development and redevelopment properties that are pre-leased, we cease capitalization when revenue recognition commences, which is upon substantial completion of tenant improvements deemed to be the Company’s asset for accounting purposes. • For office and retail development and redevelopment properties that are not pre-leased, we may not immediately build out the tenant improvements. Therefore, we cease capitalization when revenue recognition commences upon substantial completion of the tenant improvements deemed to be the Company's asset for accounting purposes, but in any event, no later than one year after the cessation of major construction activities. We also cease capitalization on a development or redevelopment property when activities necessary to prepare the property for its intended use have been suspended. • For office and retail development or redevelopment properties with multiple tenants and staged leasing, we cease capitalization and begin depreciation on the portion of the development or redevelopment property for which revenue recognition has commenced. • For residential development properties, we cease capitalization when the property is substantially complete and available for occupancy. Once major base building construction activities have ceased and the development or redevelopment property or phases of the development or redevelopment project is placed in service, which may occur in phases or for an entire building or project, the costs capitalized to construction in progress are transferred to land and improvements, buildings and improvements, and deferred leasing costs on our consolidated balance sheets as the historical cost of the property. Depreciation and Amortization of Buildings and Improvements The costs of buildings and improvements and tenant improvements are depreciated using the straight-line method of accounting over the estimated useful lives set forth in the table below. Depreciation expense for buildings and improvements for the three years ended December 31, 2019 , 2018 , and 2017 was $211.9 million , $198.6 million , and $190.5 million , respectively. Asset Description Depreciable Lives Buildings and improvements 25 – 40 years Tenant improvements 1 – 20 years (1) ________________________ (1) Tenant improvements are amortized over the shorter of the lease term or the estimated useful life. Real Estate Assets Held for Sale, Dispositions and Discontinued Operations A real estate asset is classified as held for sale when certain criteria are met, including but not limited to the availability of the asset for immediate sale, the existence of an active program to locate a buyer and the probable sale or transfer of the asset within one year. If such criteria are met, we present the applicable assets and liabilities related to the real estate asset, if material, separately on the balance sheet as held for sale and we would cease to record depreciation and amortization expense. Real estate assets held for sale are reported at the lower of their carrying value or their estimated fair value less the estimated costs to sell. As of December 31, 2019 and 2018 , we did not have any properties classified as held for sale. Property disposals representing a strategic shift that have (or will have) a major effect on the Company’s operations and financial results, such as a major line of business, a major geographical area or a major equity investment, are required

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2019
Asset Acquisitions [Abstract]
Acquisitions	Acquisitions Operating Property Acquisitions During the year ended December 31, 2019 , we acquired the 19 -building creative office campus listed below in one transaction from an unrelated third party. During the year ended December 31, 2018 , we acquired the four operating properties listed below in two transactions from unrelated third parties. Property Date of Acquisition Number of Buildings Rentable Square Feet (unaudited) Occupancy as of December 31, 2019 (unaudited) Purchase Price (in millions) (1) 2019 Acquisitions 3101-3243 La Cienega Boulevard, Culver City, CA (2) October 15, 2019 19 151,908 100.0 % $ 186.0 2018 Acquisitions 345, 347 & 349 Oyster Point Boulevard, South San Francisco, CA January 31, 2018 3 145,530 100.0 % $ 111.0 345 Brannan Street, San Francisco, CA (3) December 21, 2018 1 110,050 99.7 % 146.0 Total (4) 4 255,580 $ 257.0 ________________________ (1) Excludes acquisition-related costs. (2) The results of operations for the properties acquired during 2019 contributed $3.7 million to revenue and a net loss of $0.1 million primarily due to a write-off of lease-related intangible assets as a result of an early lease termination. (3) At December 31, 2018 , this property was temporarily being held in a separate VIE to facilitate potential Section 1031 Exchanges. During January 2019, the Company completed the Section 1031 Exchange related to this VIE. (4) The results of operations for the properties acquired during 2018 contributed $8.0 million and $1.7 million to revenue and net income, respectively, for the year ended December 31, 2018 . The related assets, liabilities and results of operations of the acquired properties are included in the consolidated financial statements as of the date of acquisition. The following table summarizes the estimated fair values of the assets and liabilities assumed at the respective acquisition dates for our 2019 and 2018 operating property acquisitions, respectively: Total 2019 Operating Property Acquisitions (1) Total 2018 Operating Property Acquisitions (2) Assets Land and improvements $ 150,561 $ 80,269 Buildings and improvements (3) 30,932 172,059 Deferred leasing costs and acquisition-related intangible assets (4) 12,063 13,593 Right of use ground lease asset (5) 13,334 — Total assets acquired $ 206,890 $ 265,921 Liabilities Acquisition-related intangible liabilities (6) $ 9,950 $ 8,921 Ground lease liability (5) 10,940 — Total liabilities assumed $ 20,890 $ 8,921 Net assets and liabilities acquired $ 186,000 $ 257,000 ________________________ (1) The purchase price of the acquisition completed during the year ended December 31, 2019 was less than 10% of the Company’s total assets as of December 31, 2018 . (2) The purchase price of the two acquisitions completed during the year ended December 31, 2018 were individually less than 5% and in aggregate less than 10% of the Company’s total assets as of December 31, 2017 . (3) Represents buildings, building improvements and tenant improvements. (4) For the 2019 operating property acquisition, represents in-place leases (approximately $9.2 million with a weighted average amortization period of 3.3 years ) and leasing commissions (approximately $2.9 million with a weighted average amortization period of 3.5 years ). For the 2018 operating property acquisitions, represents in-place leases (approximately $11.8 million with a weighted average amortization period of 1.3 years ) and leasing commissions (approximately $1.8 million with a weighted average amortization period of 6.6 years ). (5) We evaluated the ground lease assumed in connection with the 2019 operating property acquisition and concluded it met the criteria to be classified as an operating lease. The discount rate used in determining the present value of the minimum future lease payments was 4.79% . The right of use asset ground lease asset is equal to the ground lease liability adjusted for above and below market intangibles and deferred leasing costs. Refer to Note 18 “Commitments and Contingencies” for further discussion of the Company's ground lease obligations. (6) For the 2019 operating property acquisition, represents below-market leases (approximately $10.0 million with a weighted average amortization period of 3.5 years ). For the 2018 operating property acquisitions, represents below-market leases (approximately $8.9 million with a weighted average amortization period of 9.8 years ). Development Project Acquisitions During the year ended December 31, 2019 , we acquired the following development sites in two transactions from unrelated third parties. The acquisitions were funded from various sources of liquidity including proceeds from the Company’s unsecured revolving credit facility, the issuance of debt and the settlement of the Company’s 2018 forward equity sales agreements. During the year ended December 31, 2018 , we acquired a development site adjacent to the three operating properties we acquired in January 2018, from an unrelated third party. The acquisition was funded with proceeds from the Company’s unsecured revolving credit facility and the Company’s at-the-market stock offering program. Project Date of Acquisition City/Submarket Purchase Price (in millions) 2019 Acquisitions 1335 Broadway & 901 Park Boulevard, San Diego, CA (1) August 19, 2019 East Village $ 40.0 Seattle CBD Project (2) December 12, 2019 Seattle CBD 133.0 Total 2019 Acquisitions $ 173.0 2018 Acquisitions Kilroy Oyster Point (3) June 1, 2018 South San Francisco $ 308.2 Total 2018 Acquisitions $ 308.2 ________________________ (1) Excludes acquisition-related costs. In connection with this acquisition, we also recorded $4.0 million in accrued liabilities and environmental remediation liabilities at the date of acquisition, which are not included in the purchase price above. As of December 31, 2019 , the purchase price and our current estimate of assumed liabilities are included in undeveloped land and construction in progress and the assumed liabilities are included in accounts payable, accrued expenses and other liabilities on the Company’s consolidated balance sheets. (2) Excludes acquisition-related costs. In connection with this acquisition, we also recorded $6.3 million in accrued liabilities and environmental remediation liabilities at the date of acquisition, which are not included in the purchase price above. As of December 31, 2019 , the purchase price and our current estimate of assumed liabilities are included in undeveloped land and construction in progress and the assumed liabilities are included in accounts payable, accrued expenses and other liabilities on the Company’s consolidated balance sheets. In addition, as of December 31, 2019 , the Company had $10.0 million in restricted cash, which is excluded from the purchase price above, related to this acquisition which may be payable to the seller only if certain events occur within three years following the date of acquisition. (3) Excludes acquisition-related costs. In connection with this acquisition, we also recorded $40.6 million in accrued liabilities and environmental remediation liabilities at the date of acquisition, which are not included in the purchase price above. As of December 31, 2018 , the purchase price and our current estimate of assumed liabilities are included in undeveloped land and construction in progress and the assumed liabilities are included in accounts payable, accrued expenses and other liabilities on the Company’s consolidated balance sheets. In addition to the acquisitions listed above, during 2019, we acquired an additional land parcel for an existing development project for $99.5 million . Acquisition Costs During the years ended December 31, 2019 , 2018 , and 2017 , we capitalized $1.6 million , $3.8 million , and $4.6 million

Dispositions

Dispositions	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions Operating Property Dispositions The following table summarizes the operating properties sold during the years ended December 31, 2019 , 2018 and 2017 : Location Month of Disposition Number of Buildings Rentable Square Feet (unaudited) Sales Price (in millions) (1) 2019 Dispositions 2829 Townsgate Road, Thousand Oaks, CA May 1 84,098 $ 18.3 2211 Michelson Drive, Irvine, CA October 1 271,556 115.5 Total 2019 Dispositions 2 355,654 $ 133.8 2018 Dispositions 1310-1327 Chesapeake Terrace, Sunnyvale, CA November 4 266,982 $ 160.3 Plaza Yarrow Bay Properties (2) November 4 279,924 134.5 23925, 23975, & 24025 Park Sorrento, Calabasas, CA December 3 225,340 78.2 Total 2018 Dispositions 11 772,246 $ 373.0 2017 Dispositions 5717 Pacific Center Boulevard, San Diego, CA January 1 67,995 $ 12.1 Sorrento Mesa and Mission Valley Properties (3) September 10 675,143 174.5 Total 2017 Dispositions 11 743,138 $ 186.6 __________________ (1) Represents gross sales price before broker commissions and closing costs. (2) The Plaza Yarrow Bay Properties include the following properties: 10210, 10220 and 10230 NE Points Drive & 3933 Lake Washington Boulevard NE in Kirkland, Washington. (3) The Sorrento Mesa and Mission Valley Properties includes the following properties: 10390, 10394, 10398, 10421, 10445 and 10455 Pacific Center Court, 2355, 2365, 2375 and 2385 Northside Drive and Pacific Corporate Center - Lot 8, a 5.0 acre undeveloped land parcel. The total gains on the sales of the operating properties sold during the years ended December 31, 2019 , 2018 and 2017 were $36.8 million , $142.9 million and $39.5 million , respectively. Land Dispositions We did not dispose of any land parcels during the year ended December 31, 2019 . During the year ended December 31, 2018 , in connection with the Plaza Yarrow Bay Properties disposition listed above, we recognized a gain on sale of land of $11.8 million . During the year ended December 31, 2017 , in connection with the Sorrento Mesa and Mission Valley Properties disposition listed above, we recognized a gain on sale of land of $0.4 million . Restricted Cash Related to Dispositions We did not have any restricted cash related to dispositions or Section 1031 Exchanges as of December 31, 2019 . As of December 31, 2018 , approximately $113.1 million of net proceeds related to the operating property dispositions during the year ended December 31, 2018 were temporarily being held at a qualified intermediary at our direction, for the purpose of facilitating a Section 1031 Exchange. The cash proceeds were included in restricted cash on our consolidated balance sheets at December 31, 2018

Deferred Leasing Costs and Acqu

Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net	Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net The following table summarizes our deferred leasing costs and acquisition-related intangible assets (acquired value of leasing costs, above-market operating leases, in-place leases and below-market ground lease obligation) and intangible liabilities (acquired value of below-market operating leases and above-market ground lease obligation) as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Deferred Leasing Costs and Acquisition-related Intangible Assets, net: Deferred leasing costs $ 286,026 $ 266,905 Accumulated amortization (100,145 ) (100,805 ) Deferred leasing costs, net 185,881 166,100 Above-market operating leases 611 2,836 Accumulated amortization (116 ) (2,150 ) Above-market operating leases, net 495 686 In-place leases 58,076 66,526 Accumulated amortization (31,647 ) (36,174 ) In-place leases, net 26,429 30,352 Below-market ground lease obligation — 490 Accumulated amortization — (54 ) Below-market ground lease obligation, net (1) — 436 Total deferred leasing costs and acquisition-related intangible assets, net $ 212,805 $ 197,574 Acquisition-related Intangible Liabilities, net: (2) Below-market operating leases $ 51,263 $ 53,523 Accumulated amortization (27,171 ) (29,978 ) Below-market operating leases, net 24,092 23,545 Above-market ground lease obligation — 6,320 Accumulated amortization — (727 ) Above-market ground lease obligation, net (1) — 5,593 Total acquisition-related intangible liabilities, net $ 24,092 $ 29,138 _______________ (1) Upon adoption of Topic 842 on January 1, 2019 (refer to Note 2 “Basis of Presentation and Significant Accounting Policies”), we no longer separately recognize above or below-market ground lease obligations. Such amounts are reflected in the net book value of the right of use ground lease asset on our consolidated balance sheets. Refer to Note 18 “Commitments and Contingencies” for further discussion of our ground lease obligations. (2) Included in deferred revenue and acquisition-related intangible liabilities, net in the consolidated balance sheets. The following table sets forth amortization related to deferred leasing costs and acquisition-related intangibles for the years ended December 31, 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 (in thousands) Deferred leasing costs (1) $ 35,779 $ 34,341 $ 31,675 Above-market operating leases (2) 192 444 2,240 In-place leases (1) 18,615 15,915 18,650 Below-market ground lease obligation (3) — 8 8 Below-market operating leases (4) (9,398 ) (10,192 ) (10,768 ) Above-market ground lease obligation (3) — (101 ) (101 ) Total $ 45,188 $ 40,415 $ 41,704 _______________ (1) The amortization of deferred leasing costs and in-place leases is recorded to depreciation and amortization expense and the amortization of lease incentives is recorded as a reduction to rental income in the consolidated statements of operations for the periods presented. (2) The amortization of above-market operating leases is recorded as a decrease to rental income in the consolidated statements of operations for the periods presented. (3) Upon adoption of Topic 842 on January 1, 2019 (refer to Note 2 “Basis of Presentation and Significant Accounting Policies”), we no longer separately recognize above or below-market ground lease obligations. Refer to Note 18 “Commitments and Contingencies” for further discussion of our ground lease obligations. (4) The amortization of below-market operating leases is recorded as an increase to rental income in the consolidated statements of operations for the periods presented. The following table sets forth the estimated annual amortization expense related to deferred leasing costs and acquisition-related intangibles as of December 31, 2019 for future periods: Year Deferred Leasing Costs Above-Market Operating Leases (1) In-Place Leases Below-Market Operating Leases (2) (in thousands) 2020 30,897 38 11,379 (7,258 ) 2021 27,043 38 6,668 (4,543 ) 2022 23,642 38 4,001 (3,553 ) 2023 19,904 38 1,641 (1,866 ) 2024 16,976 38 602 (1,090 ) Thereafter 67,419 305 2,138 (5,782 ) Total $ 185,881 $ 495 $ 26,429 $ (24,092 ) _______________ (1) Represents estimated annual amortization related to above-market operating leases. Amounts will be recorded as a decrease to rental income in the consolidated statements of operations. (2) Represents estimated annual amortization related to below-market operating leases. Amounts will be recorded as an increase to rental income in the consolidated statements of operations.

Receivables

Receivables	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Receivables	Receivables Current Receivables, net Current receivables, net is primarily comprised of contractual rents and other lease-related obligations due from tenants. The balance consisted of the following as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Current receivables $ 27,660 $ 24,815 Allowance for uncollectible tenant receivables (1) (1,171 ) (4,639 ) Current receivables, net $ 26,489 $ 20,176 _______________ (1) Refer to Note 2 “Basis of Presentation and Significant Accounting Policies” for discussion of our accounting policies related to the allowance for uncollectible tenant receivables and Note 20 “Other Significant Transactions” for additional information regarding changes in our allowance for uncollectible tenant receivables. Deferred Rent Receivables, net Deferred rent receivables, net consisted of the following as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Deferred rent receivables $ 339,489 $ 270,346 Allowance for deferred rent receivables (1) (1,552 ) (3,339 ) Deferred rent receivables, net $ 337,937 $ 267,007 _______________ (1) During the year ended December 31, 2019 , we recorded a $2.9 million net increase in rental income on our consolidated statements of operations primarily due to a $4.2 million increase in revenue related to the improved credit quality of a tenant for which we previously recorded a bad debt reserve during the year ended December 31, 2018 , partially offset by a $1.3 million decrease in revenue for other tenants with diminished credit quality during the year ended December 31, 2019 . During the year ended December 31, 2018 , we recognized $5.7 million of provision for bad debts. The provision for bad debts was primarily due to a $7.0 million provision for one tenant recognized during the second quarter of 2018, partially offset by a $1.4 million decrease in the provision for bad debts for one lease due to the assignment of the lease to a credit tenant during the second quarter of 2018.

Prepaid Expenses and Other Asse

Prepaid Expenses and Other Assets, Net	12 Months Ended
	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Assets, Net	Prepaid Expenses and Other Assets, Net Prepaid expenses and other assets, net consisted of the following at December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Furniture, fixtures and other long-lived assets, net $ 35,286 $ 36,833 Notes receivable (1) 1,651 2,113 Prepaid expenses 18,724 13,927 Total prepaid expenses and other assets, net $ 55,661 $ 52,873 _______________ (1) Notes receivable are shown net of a valuation allowance of approximately $3.6 million and $2.9 million as of December 31, 2019 and 2018

Secured and Unsecured Debt of t

Secured and Unsecured Debt of the Company	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Secured and Unsecured Debt of the Company	Secured and Unsecured Debt of the Company In this Note 8, the “Company” refers solely to Kilroy Realty Corporation and not to any of our subsidiaries. The Company itself does not hold any indebtedness. All of our secured and unsecured debt is held directly by the Operating Partnership. The Company generally guarantees all the Operating Partnership’s unsecured debt obligations including the unsecured revolving credit facility, the $150.0 million unsecured term loan facility and all of the unsecured senior notes. At December 31, 2019 and 2018 , the Operating Partnership had $3.3 billion and $2.6 billion , respectively, outstanding in total, including unamortized discounts and deferred financing costs, under these unsecured debt obligations. In addition, although the remaining $0.3 billion of the Operating Partnership’s debt as of December 31, 2019 and 2018 , is secured and non-recourse to the Company, the Company provides limited customary secured debt guarantees for items such as voluntary bankruptcy, fraud, misapplication of payments and environmental liabilities. Debt Covenants and Restrictions

Secured and Unsecured Debt of_2

Secured and Unsecured Debt of the Operating Partnership	12 Months Ended
	Dec. 31, 2019
Debt Instrument [Line Items]
Secured and Unsecured Debt of the Operating Partnership	Secured and Unsecured Debt of the Company In this Note 8, the “Company” refers solely to Kilroy Realty Corporation and not to any of our subsidiaries. The Company itself does not hold any indebtedness. All of our secured and unsecured debt is held directly by the Operating Partnership. The Company generally guarantees all the Operating Partnership’s unsecured debt obligations including the unsecured revolving credit facility, the $150.0 million unsecured term loan facility and all of the unsecured senior notes. At December 31, 2019 and 2018 , the Operating Partnership had $3.3 billion and $2.6 billion , respectively, outstanding in total, including unamortized discounts and deferred financing costs, under these unsecured debt obligations. In addition, although the remaining $0.3 billion of the Operating Partnership’s debt as of December 31, 2019 and 2018 , is secured and non-recourse to the Company, the Company provides limited customary secured debt guarantees for items such as voluntary bankruptcy, fraud, misapplication of payments and environmental liabilities. Debt Covenants and Restrictions
Kilroy Realty L.P. [Member]
Debt Instrument [Line Items]
Secured and Unsecured Debt of the Operating Partnership	Secured and Unsecured Debt of the Operating Partnership Secured Debt The following table sets forth the composition of our secured debt as of December 31, 2019 and 2018 : Annual Stated Interest Rate (1) GAAP Effective Rate (1)(2) Maturity Date December 31, Type of Debt 2019 2018 (in thousands) Mortgage note payable 3.57% 3.57% December 2026 $ 170,000 $ 170,000 Mortgage note payable (3) 4.48% 4.48% July 2027 89,502 91,332 Mortgage note payable (3)(4) 6.05% 3.50% June 2019 — 75,238 Total secured debt $ 259,502 $ 336,570 Unamortized Deferred Financing Costs (909 ) (1,039 ) Total secured debt, net $ 258,593 $ 335,531 ______________ (1) All interest rates presented are fixed-rate interest rates. (2) Represents the effective interest rate including the amortization of initial issuance discounts/premiums excluding the amortization of deferred financing costs. (3) The secured debt and the related properties that secure the debt are held in a special purpose entity and the properties are not available to satisfy the debts and other obligations of the Company or the Operating Partnership. (4) In February 2019, the Company repaid this mortgage note payable at par. The Operating Partnership’s secured debt was collateralized by operating properties with a combined net book value of approximately $251.2 million as of December 31, 2019 . Although our mortgage loans are secured and non-recourse to the Company and the Operating Partnership, the Company provides limited customary secured debt guarantees for items such as voluntary bankruptcy, fraud, misapplication of payments and environmental liabilities. As of December 31, 2019 , all of the Operating Partnership’s secured loans contained restrictions that would require the payment of prepayment penalties for the acceleration of outstanding debt. The mortgage notes payable are secured by deeds of trust on certain of our properties and the assignment of certain rents and leases associated with those properties. Unsecured Senior Notes The following table summarizes the balance and significant terms of the registered unsecured senior notes issued by the Operating Partnership and outstanding, including unamortized discounts of $6.5 million and $6.6 million and unamortized deferred financing costs of $18.7 million and $15.4 million as of December 31, 2019 and 2018 , respectively: Net Carrying Amount Issuance date Maturity date Stated coupon rate Effective interest rate (1) 2019 2018 (in thousands) 3.050% Unsecured Senior Notes (2) September 2019 February 2030 3.050% 3.064% $ 500,000 $ — Unamortized discount and deferred financing costs (5,998 ) — Net carrying amount $ 494,002 $ — 4.750% Unsecured Senior Notes (3) November 2018 December 2028 4.750% 4.800% $ 400,000 $ 400,000 Unamortized discount and deferred financing costs (4,446 ) (4,960 ) Net carrying amount $ 395,554 $ 395,040 4.350% Unsecured Senior Notes (4) October 2018 October 2026 4.350% 4.350% $ 200,000 $ 200,000 Unamortized discount and deferred financing costs (1,186 ) (1,375 ) Net carrying amount $ 198,814 $ 198,625 4.300% Unsecured Senior Notes (4) July 2018 July 2026 4.300% 4.300% $ 50,000 $ 50,000 Unamortized discount and deferred financing costs (290 ) (342 ) Net carrying amount $ 49,710 $ 49,658 3.450% Unsecured Senior Notes (5) December 2017 December 2024 3.450% 3.470% $ 425,000 $ 425,000 Unamortized discount and deferred financing costs (2,907 ) (3,493 ) Net carrying amount $ 422,093 $ 421,507 3.450% Unsecured Senior Notes (6) February 2017 February 2029 3.450% 3.450% $ 75,000 $ 75,000 Unamortized discount and deferred financing costs (390 ) (432 ) Net carrying amount $ 74,610 $ 74,568 3.350% Unsecured Senior Notes (6) February 2017 February 2027 3.350% 3.350% $ 175,000 $ 175,000 Unamortized discount and deferred financing costs (825 ) (941 ) Net carrying amount $ 174,175 $ 174,059 4.375% Unsecured Senior Notes (7) September 2015 October 2025 4.375% 4.444% $ 400,000 $ 400,000 Unamortized discount and deferred financing costs (3,185 ) (3,738 ) Net carrying amount $ 396,815 $ 396,262 4.250% Unsecured Senior Notes (8) July 2014 August 2029 4.250% 4.350% $ 400,000 $ 400,000 Unamortized discount and deferred financing costs (5,100 ) (5,632 ) Net carrying amount $ 394,900 $ 394,368 3.800% Unsecured Senior Notes (9) January 2013 January 2023 3.800% 3.800% $ 300,000 $ 300,000 Unamortized discount and deferred financing costs (834 ) (1,108 ) Net carrying amount $ 299,166 $ 298,892 Total Unsecured Senior Notes, Net $ 2,899,839 $ 2,402,979 ________________________ (1) Represents the effective interest rate including the amortization of initial issuance discounts, excluding the amortization of deferred financing costs. (2) Interest on these notes is payable semi-annually in arrears on February 15th and August 15th of each year, beginning on February 15, 2020. (3) Interest on these notes is payable semi-annually in arrears on June 15th and December 15th of each year. (4) Interest on these notes is payable semi-annually in arrears on April 18th and October 18th of each year. (5) Interest on these notes is payable semi-annually in arrears on June 15th and December 15th of each year. (6) Interest on these notes is payable semi-annually in arrears on February 17th and August 17th of each year. (7) Interest on these notes is payable semi-annually in arrears on April 1st and October 1st of each year. (8) Interest on these notes is payable semi-annually in arrears on February 15th and August 15th of each year. (9) Interest on these notes is payable semi-annually in arrears on January 15th and July 15th of each year. Unsecured Senior Notes - Registered Offerings In September 2019 , the Operating Partnership issued $500.0 million of aggregate principal amount of unsecured senior notes in a registered public offering. The outstanding balance of the unsecured senior notes is included in unsecured debt, net of an initial issuance discount of $0.6 million , on our consolidated balance sheets. The unsecured senior notes, which are scheduled to mature on February 15, 2030 , require semi-annual interest payments each February and August based on a stated annual interest rate of 3.050% . The Operating Partnership may redeem the notes at any time prior to February 15, 2030 , either in whole or in part, subject to the payment of an early redemption premium prior to a par call option period commencing three months prior to maturity. In November 2018, the Operating Partnership issued $400.0 million of aggregate principal amount of unsecured senior notes in a registered public offering. The outstanding balance of the unsecured senior notes is included in unsecured debt, net of initial issuance discount of $1.5 million , on our consolidated balance sheets. The unsecured senior notes, which are scheduled to mature on December 15, 2028 , require semi-annual interest payments each June and December based on a stated annual interest rate of 4.750% . The Operating Partnership may redeem the notes at any time prior to December 15, 2028 , either in whole or in part, subject to the payment of an early redemption premium subject to a par call option. In December 2018, we used a portion of the net proceeds from the issuance of our $400.0 million , 4.750% unsecured senior notes to early redeem, at our option, the $250.0 million aggregate principal amount of our outstanding 6.625% unsecured senior notes that were scheduled to mature on June 1, 2020 . In connection with our early redemption, we incurred a $12.6 million loss on early extinguishment of debt comprised of an $11.8 million premium paid to the note holders at the redemption date and a $0.8 million write-off of the unamortized discount and unamortized deferred financing costs. Unsecured Senior Notes - Private Placement In May 2018, the Operating Partnership entered into a note purchase agreement in a private placement (the “2018 Note Purchase Agreement”) in connection with the issuance and sale of $50.0 million principal amount of the Operating Partnership’s 4.30% Senior Notes, Series A, due July 18, 2026 (the “Series A Notes due 2026”), and $200.0 million principal amount of the Operating Partnership’s 4.35% Senior Notes, Series B, due October 18, 2026 (the “Series B Notes due 2026” and, together with the Series A Notes, the “Series A and B Notes due 2026”), as shown in the table above. The Company drew the full amount of the Series A Notes due 2026 on July 18, 2018. On October 22, 2018, the Company drew the full amount of the Series B Notes due 2026. The Series A and B Notes due 2026 mature on their respective due dates, unless earlier redeemed or prepaid pursuant to the terms of the 2018 Note Purchase Agreement. Interest on the Series A and B Notes due 2026 is payable semi-annually in arrears on April 18 and October 18 of each year beginning April 18, 2019. As of December 31, 2019 , there was $50.0 million and $200.0 million issued and outstanding aggregate principal amount of Series A and Series B Notes due 2026, respectively. The Operating Partnership may, at its option and upon notice to the purchasers of the Series A and B Notes due 2026, prepay at any time all, or from time to time any part of the principal amounts then outstanding (in an amount not less than 5% of the aggregate principal amount of the Series A and B Notes due 2026 then outstanding in the case of a partial prepayment), at 100% of the principal amount so prepaid, plus the make-whole amount determined for the prepayment date with respect to such principal amount as set forth in the 2018 Note Purchase Agreement. In connection with the issuance of the Series A and B Notes due 2026, the Company entered into an agreement whereby it will guarantee the payment by the Operating Partnership of all amounts due with respect to the Series A and B Notes due 2026 and the performance by the Operating Partnership of its obligations under the 2018 Note Purchase Agreement. Unsecured Revolving Credit Facility and Term Loan Facility The following table summarizes the balance and terms of our unsecured revolving credit facility as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Outstanding borrowings $ 245,000 $ 45,000 Remaining borrowing capacity 505,000 705,000 Total borrowing capacity (1) $ 750,000 $ 750,000 Interest rate (2) 2.76 % 3.48 % Facility fee-annual rate (3) 0.200% Maturity date July 2022 _______________ (1) We may elect to borrow, subject to bank approval and obtaining commitments for any additional borrowing capacity, up to an additional $600.0 million under an accordion feature under the terms of the unsecured revolving credit facility and unsecured term loan facility. (2) Our unsecured revolving credit facility interest rate was calculated based on the contractual rate of LIBOR plus 1.000% as of December 31, 2019 and 2018 . (3) Our facility fee is paid on a quarterly basis and is calculated based on the total borrowing capacity. In addition to the facility fee, we incurred debt origination and legal costs. As of December 31, 2019 and 2018 , $3.4 million and $4.7 million of unamortized deferred financing costs, respectively, which are included in prepaid expenses and other assets, net on our consolidated balance sheets, remained to be amortized through the maturity date of our unsecured revolving credit facility. The Company intends to borrow under the unsecured revolving credit facility from time to time for general corporate purposes, to finance development and redevelopment expenditures, to fund potential acquisitions and to potentially repay long-term debt. During the first quarter of 2018, we borrowed the full $150.0 million borrowing capacity of our unsecured term loan facility. In connection with the funding of the outstanding borrowings, we transferred $30.0 million of outstanding borrowings under the unsecured revolving credit facility to the balance of our unsecured term loan facility. As a result, only $120.0 million of cash proceeds were received from the funding of the unsecured term loan facility. The following table summarizes the balance and terms of our unsecured term loan facility as of December 31, 2019 and 2018 , which is included in unsecured debt, net on our consolidated balance sheets: December 31, 2019 December 31, 2018 (in thousands) Outstanding borrowings $ 150,000 $ 150,000 Remaining borrowing capacity — — Total borrowing capacity (1) $ 150,000 $ 150,000 Interest rate (2) 2.85 % 3.49 % Undrawn facility fee-annual rate 0.200% Maturity date July 2022 _______________ (1) As of December 31, 2019 and 2018 , $0.7 million and $0.9 million of unamortized deferred financing costs, respectively, remained to be amortized through the maturity date of our unsecured term loan facility. (2) Our unsecured term loan facility interest rate was calculated based on the contractual rate of LIBOR plus 1.100% as of December 31, 2019 and 2018 . Debt Covenants and Restrictions The unsecured revolving credit facility, the unsecured term loan facility, the unsecured senior notes, the Series A and B Notes due 2026 and Series A and B Notes due 2027 and 2029 and certain other secured debt arrangements contain covenants and restrictions requiring us to meet certain financial ratios and reporting requirements. Some of the more restrictive financial covenants include a maximum ratio of total debt to total asset value, a minimum fixed-charge coverage ratio, a minimum unsecured debt ratio and a minimum unencumbered asset pool debt service coverage ratio. Noncompliance with one or more of the covenants and restrictions could result in the full principal balance of the associated debt becoming immediately due and payable. We believe we were in compliance with all of our debt covenants as of December 31, 2019 and 2018 . Debt Maturities The following table summarizes the stated debt maturities and scheduled amortization payments as of December 31, 2019 : Year (in thousands) 2020 $ 5,137 2021 5,342 2022 400,554 2023 305,775 2024 431,006 Thereafter 2,431,688 Total aggregate principal value (1) $ 3,579,502 ________________________ (1) Includes gross principal balance of outstanding debt before the effect of the following at December 31, 2019 : $20.3 million of unamortized deferred financing costs for the unsecured term loan facility, unsecured senior notes and secured debt and $6.5 million of unamortized discounts for the unsecured senior notes. Capitalized Interest and Loan Fees The following table sets forth gross interest expense, including debt discount/premium and deferred financing cost amortization, net of capitalized interest, for the years ended 2019 , 2018 and 2017 . The interest expense capitalized was recorded as a cost of development and increased the carrying value of undeveloped land and construction in progress. Year Ended December 31, 2019 2018 2017 (in thousands) Gross interest expense $ 129,778 $ 117,789 $ 112,577 Capitalized interest and deferred financing costs (81,241 ) (68,068 ) (46,537 ) Interest expense $ 48,537 $ 49,721 $ 66,040

Deferred Revenue and Acquisitio

Deferred Revenue and Acquisition-Related Intangible Liabilities, net	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Deferred Revenue and Acquisition-Related Intangible Liabilities, net	Deferred Revenue and Acquisition-Related Intangible Liabilities, net Deferred revenue and acquisition-related intangible liabilities, net consisted of the following at December 31, 2019 and 2018 : December 31, 2019 2018 (in thousands) Deferred revenue related to tenant-funded tenant improvements $ 96,271 $ 104,558 Other deferred revenue 19,125 15,950 Acquisition-related intangible liabilities, net (1) 24,092 29,138 Total $ 139,488 $149,646 ________________________ (1) See Note 5 “Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net” for additional information regarding our acquisition-related intangible liabilities. Deferred Revenue Related to Tenant-funded Tenant Improvements During the years ended December 31, 2019 , 2018 , and 2017 , $19.2 million , $18.4 million and $16.8 million , respectively, of deferred revenue related to tenant-funded tenant improvements was amortized and recognized as rental income. The following is the estimated amortization of deferred revenue related to tenant-funded tenant improvements as of December 31, 2019 for the next five years and thereafter: Year Ending (in thousands) 2020 $ 16,935 2021 15,426 2022 14,320 2023 12,553 2024 10,318 Thereafter 26,719 Total $ 96,271

Noncontrolling Interests on the

Noncontrolling Interests on the Company’s Consolidated Financial Statements	12 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interests on the Company’s Consolidated Financial Statements	Noncontrolling Interests on the Company’s Consolidated Financial Statements Common Units of the Operating Partnership The Company owned a 98.1% and 98.0% common general partnership interest in the Operating Partnership as of December 31, 2019 and 2018 , respectively. The remaining 1.9% and 2.0% common limited partnership interest as of December 31, 2019 and 2018 , respectively, was owned by non-affiliated investors and certain of our executive officers and directors in the form of noncontrolling common units. There were 2,023,287 and 2,025,287 common units outstanding held by these investors, executive officers and directors as of December 31, 2019 and 2018 , respectively. The decrease in the common units from December 31, 2018 to December 31, 2019 was attributable to 2,000 common unit redemptions. The noncontrolling common units may be redeemed by unitholders for cash. Except under certain circumstances, we, at our option, may satisfy the cash redemption obligation with shares of the Company’s common stock on a one -for-one basis. If satisfied in cash, the value for each noncontrolling common unit upon redemption is the amount equal to the average of the closing quoted price per share of the Company’s common stock, par value $.01 per share, as reported on the NYSE for the ten trading days immediately preceding the applicable redemption date. The aggregate value upon redemption of the then-outstanding noncontrolling common units was $167.7 million and $126.4 million as of December 31, 2019 and 2018 , respectively. This redemption value does not necessarily represent the amount that would be distributed with respect to each noncontrolling common unit in the event of our termination or liquidation. In the event of our termination or liquidation, it is expected in most cases that each common unit would be entitled to a liquidating distribution equal to the liquidating distribution payable in respect of each share of the Company’s common stock. Noncontrolling Interest in Consolidated Property Partnerships In August 2016, the Operating Partnership entered into agreements with Norges Bank Real Estate Management (“NBREM”) whereby NBREM made contributions, through two REIT subsidiaries, for a 44% common equity interest in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. The transactions did not meet the criteria to qualify as sales of real estate because the Company continues to effectively control the properties and therefore continued to account for the 100 First Street and 303 Second Street office properties on a consolidated basis in its financial statements. At formation, the Company accounted for the transactions as equity transactions and recognized noncontrolling interests in its consolidated balance sheets. The noncontrolling interests in 100 First LLC and 303 Second LLC as of December 31, 2019 and 2018 were $189.6 million and $186.4 million , respectively. The remaining amount of noncontrolling interests in consolidated property partnerships represents the third party equity interest in Redwood LLC. This noncontrolling interest was $5.8 million and $6.0 million as of December 31, 2019 and 2018 , respectively. Consolidated Property Partnerships In August 2016, the Operating Partnership entered into agreements with NBREM whereby NBREM made contributions, through two REIT subsidiaries, for a 44% common equity interest in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. Refer to Note 11 for additional information regarding these consolidated property partnerships.

Noncontrolling Interests on t_2

Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements	12 Months Ended
	Dec. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements	Noncontrolling Interests on the Company’s Consolidated Financial Statements Common Units of the Operating Partnership The Company owned a 98.1% and 98.0% common general partnership interest in the Operating Partnership as of December 31, 2019 and 2018 , respectively. The remaining 1.9% and 2.0% common limited partnership interest as of December 31, 2019 and 2018 , respectively, was owned by non-affiliated investors and certain of our executive officers and directors in the form of noncontrolling common units. There were 2,023,287 and 2,025,287 common units outstanding held by these investors, executive officers and directors as of December 31, 2019 and 2018 , respectively. The decrease in the common units from December 31, 2018 to December 31, 2019 was attributable to 2,000 common unit redemptions. The noncontrolling common units may be redeemed by unitholders for cash. Except under certain circumstances, we, at our option, may satisfy the cash redemption obligation with shares of the Company’s common stock on a one -for-one basis. If satisfied in cash, the value for each noncontrolling common unit upon redemption is the amount equal to the average of the closing quoted price per share of the Company’s common stock, par value $.01 per share, as reported on the NYSE for the ten trading days immediately preceding the applicable redemption date. The aggregate value upon redemption of the then-outstanding noncontrolling common units was $167.7 million and $126.4 million as of December 31, 2019 and 2018 , respectively. This redemption value does not necessarily represent the amount that would be distributed with respect to each noncontrolling common unit in the event of our termination or liquidation. In the event of our termination or liquidation, it is expected in most cases that each common unit would be entitled to a liquidating distribution equal to the liquidating distribution payable in respect of each share of the Company’s common stock. Noncontrolling Interest in Consolidated Property Partnerships In August 2016, the Operating Partnership entered into agreements with Norges Bank Real Estate Management (“NBREM”) whereby NBREM made contributions, through two REIT subsidiaries, for a 44% common equity interest in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. The transactions did not meet the criteria to qualify as sales of real estate because the Company continues to effectively control the properties and therefore continued to account for the 100 First Street and 303 Second Street office properties on a consolidated basis in its financial statements. At formation, the Company accounted for the transactions as equity transactions and recognized noncontrolling interests in its consolidated balance sheets. The noncontrolling interests in 100 First LLC and 303 Second LLC as of December 31, 2019 and 2018 were $189.6 million and $186.4 million , respectively. The remaining amount of noncontrolling interests in consolidated property partnerships represents the third party equity interest in Redwood LLC. This noncontrolling interest was $5.8 million and $6.0 million as of December 31, 2019 and 2018 , respectively. Consolidated Property Partnerships In August 2016, the Operating Partnership entered into agreements with NBREM whereby NBREM made contributions, through two REIT subsidiaries, for a 44% common equity interest in two existing companies that owned the Company’s 100 First Street and 303 Second Street office properties located in San Francisco, California. Refer to Note 11 for additional information regarding these consolidated property partnerships.

Stockholders' Equity of the Com

Stockholders' Equity of the Company	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity of the Company	Stockholders’ Equity of the Company Common Stock 2018 Common Stock Forward Equity Sale Agreements In August 2018, the Company entered into forward equity sale agreements with certain financial institutions acting as forward purchasers in connection with an offering of 5,000,000 shares of common stock at an initial gross offering price of $360.5 million , or $72.10 per share, before underwriting discounts, commissions and offering expenses. The forward purchasers borrowed and sold an aggregate of 5,000,000 shares of common stock in the offering. The Company did not receive any proceeds from the sale of its shares of common stock by the forward purchasers at the time of the offering. In July 2019, the Company physically settled these forward equity sale agreements. Upon settlement, the Company issued 5,000,000 shares of common stock for net proceeds of $354.3 million and contributed the net proceeds to the Operating Partnership in exchange for an equal number of units in the Operating Partnership. At-The-Market Stock Offering Programs Under our at-the-market stock offering programs, which commenced in December 2014 and June 2018, we may offer and sell shares of our common stock from time to time in “at-the-market” offerings. During the year ended December 31, 2018, the Company completed its existing at-the-market stock offering program (the “2014 At-The-Market Program”) under which we sold an aggregate of $300.0 million in gross sales of shares. In June 2018, the Company commenced a new at-the-market stock offering program (the “2018 At-The-Market Program”) under which we may offer and sell shares of our common stock with an aggregate gross sales price of up to $500.0 million . In connection with the 2018 At-The-Market Program, the Company may also, at its discretion, enter into forward equity sale agreements. The use of forward equity sale agreements would allow the Company to lock in a share price on the sale of shares of our common stock at the time an agreement is executed, but defer receiving the proceeds from the sale of shares until a later date. During the year ended December 31, 2019 , we executed various 12-month forward equity sale agreements under the 2018 Program with financial institutions acting as forward purchasers to sell 3,147,110 shares of common stock at a weighted average sales price of $80.08 per share before underwriting discounts, commissions and offering expenses. The Company did not directly sell any shares of our common stock under the 2018 At-The-Market Program during the year and did not receive any proceeds from the sale of its shares of common stock by the forward purchasers. The Company currently expects to fully physically settle the forward equity sale agreements and receive cash proceeds upon one or more settlement dates, at the Company’s discretion, prior to the final settlement dates in the first quarter of 2020 through the first quarter of 2021, at which time we expect to receive aggregate net cash proceeds at settlement equal to the number of shares specified in such forward equity sale agreement multiplied by the relevant forward price per share. The weighted average forward sale price that we expect to receive upon physical settlement of the agreements will be subject to adjustment for (i) a floating interest rate factor equal to a specified daily rate less a spread, (ii) the forward purchasers’ stock borrowing costs and (iii) scheduled dividends during the term of the agreements. We have not settled any portion of these forward equity sale agreements as of the date of this filing. Upon physical settlement, the Company will contribute the net proceeds from the issuance of shares of our common stock to the Operating Partnership in exchange for an equal number of units in the Operating Partnership. During the year ended December 31, 2018 , we sold 447,466 shares of common stock under the 2018 At-The-Market Program and 1,369,729 shares of common stock under the 2014 At-The-Market Program. Since commencement of the 2018 At-The-Market Program through December 31, 2019 , we have directly sold 447,466 shares of common stock, and an additional 3,147,110 shares have been sold by forward purchasers under forward equity sale agreements, which have not been settled as of the date of this filing. As of December 31, 2019 , approximately $214.2 million remains available to be sold under this program. Actual future sales will depend upon a variety of factors, including, but not limited to, market conditions, the trading price of the Company’s common stock and our capital needs. We have no obligation to sell the remaining shares available for sale under this program. The following table sets forth information regarding direct sales of our common stock under our at-the-market offering programs for the years ended December 31, 2018 and 2017 : Year Ended December 31, 2018 2017 (in millions, except share data) Shares of common stock sold during the period 1,817,195 235,077 Weighted average price per share of common stock $ 73.64 $ 75.40 Aggregate gross proceeds $ 133.8 $ 17.7 Aggregate net proceeds after selling commissions $ 132.1 $ 17.5 The proceeds from sales were used to fund acquisitions, development expenditures and general corporate purposes including repayment of borrowings under the unsecured revolving credit facility. Common Stock Repurchases An aggregate of 4,935,826 shares currently remain eligible for repurchase under a share repurchase program approved by the Company’s board of directors in 2016. The Company did not repurchase shares of common stock under this program during the three years ended December 31, 2019 , 2018 and 2017 . Accrued Dividends and Distributions The following tables summarize accrued dividends and distributions for the noted outstanding shares of common stock and noncontrolling units as of December 31, 2019 and 2018 : December 31, 2019 2018 (in thousands) Dividends and Distributions payable to: Common stockholders $ 51,418 $ 45,840 Noncontrolling common unitholders of the Operating Partnership 981 922 RSU holders (1) 820 797 Total accrued dividends and distribution to common stockholders and noncontrolling unitholders $ 53,219 $ 47,559 ______________________ (1) The amount includes the value of the dividend equivalents that will be paid with additional RSUs (see Note 15 “Share-Based Compensation” for additional information). December 31, 2019 2018 Outstanding Shares and Units: Common stock (1) 106,016,287 100,746,988 Noncontrolling common units 2,023,287 2,025,287 RSUs (2) 1,651,905 1,711,628 ______________________ (1) The amount includes nonvested shares. (2) The amount includes nonvested RSUs. Does not include 932,675 and 1,018,337 market measure-based RSUs because not all the necessary performance conditions have been met as of December 31, 2019 and 2018 , respectively. Refer to Note 15 “Share-Based Compensation” for additional information. Preferred Stock On August 15, 2017 , the Company redeemed all 4,000,000 shares of its 6.375% Series H Cumulative Redeemable Preferred Stock (“Series H Preferred Stock”). The shares of Series H Preferred Stock were redeemed at a redemption price equal to their stated liquidation preference of $25.00 per share, representing $100.0 million in aggregate. The redemption payment did not include any additional accrued dividends because the redemption date was also the dividend payment date. On March 30, 2017 (the “Series G Redemption Date”), the Company redeemed all 4,000,000 shares of its 6.875% Series G Cumulative Redeemable Preferred Stock (“Series G Preferred Stock”). The shares of Series G Preferred Stock were redeemed at a redemption price equal to their stated liquidation preference of $25.00 per share, representing $100.0 million in aggregate, plus all accrued and unpaid dividends to the Series G Redemption Date. In connection with the redemption of the Series G and Series H Preferred Stock, during the year ended December 31, 2017 we recorded non-cash charges of $7.6 million

Partners' Capital of the Operat

Partners' Capital of the Operating Partnership	12 Months Ended
	Dec. 31, 2019
Partners' Capital [Abstract]
Partners' Capital of the Operating Partnership	Partners’ Capital of the Operating Partnership Common Units Issuance of Common Units In July 2019, the Company physically settled the forward equity sale agreements entered into in August 2018 (see Note 13 “Stockholders’ Equity of the Company”). Upon settlement, the Company issued 5,000,000 shares of common stock for net proceeds of $354.3 million and contributed the net proceeds to the Operating Partnership in exchange for 5,000,000 common units. At-The-Market Stock Offering Program The Company did not issue any shares of common stock under its at-the-market stock offering program during the year ended December 31, 2019 . During the years ended December 31, 2018 and 2017 , the Company utilized its at-the-market stock offering programs to issue shares of common stock. See Note 13 “Stockholders’ Equity of the Company” for additional information. The net offering proceeds contributed by the Company to the Operating Partnership in exchange for common units for the years ended December 31, 2019 , 2018 and 2017 are as follows: Year Ended December 31, 2018 2017 (in millions, except share and per share data) Shares of common stock contributed by the Company 1,817,195 235,077 Common units exchanged for shares of common stock by the Company 1,817,195 235,077 Aggregate gross proceeds $ 133.8 $ 17.7 Aggregate net proceeds after selling commissions $ 132.1 $ 17.5 Common Units Outstanding The following table sets forth the number of common units held by the Company and the number of common units held by non-affiliated investors and certain of our executive officers and directors in the form of noncontrolling common units as well as the ownership interest held on each respective date: December 31, 2019 December 31, 2018 Company owned common units in the Operating Partnership 106,016,287 100,746,988 Company owned general partnership interest 98.1 % 98.0 % Noncontrolling common units of the Operating Partnership 2,023,287 2,025,287 Ownership interest of noncontrolling interest 1.9 % 2.0 % For a further discussion of the noncontrolling common units during the years ended December 31, 2019 and 2018 , refer to Note 11 “Noncontrolling Interests on the Company’s Consolidated Financial Statements.” Accrued Distributions The following tables summarize accrued distributions for the noted common units as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Distributions payable to: General partner $ 51,418 $ 45,840 Common limited partners 981 922 RSU holders (1) 820 797 Total accrued distributions to common unitholders $ 53,219 $ 47,559 ______________________ (1) The amount includes the value of the dividend equivalents that will be paid with additional RSUs (see Note 15 “Share-Based Compensation” for additional information). December 31, 2019 December 31, 2018 Outstanding Units: Common units held by the general partner 106,016,287 100,746,988 Common units held by the limited partners 2,023,287 2,025,287 RSUs (1) 1,651,905 1,711,628 ______________________ (1) Does not include 932,675 and 1,018,337 market measure-based RSUs because not all the necessary performance conditions have been met as of December 31, 2019 and 2018 , respectively. Refer to Note 15 “Share-Based Compensation” for additional information. Preferred Units On August 15, 2017 , the Company redeemed all 4,000,000 shares of its 6.375% Series H Preferred Stock. For each share of Series H Preferred Stock that was outstanding, the Company had an equivalent number of 6.375% Series H Preferred Units (“Series H Preferred Units”) outstanding with substantially similar terms as the Series H Preferred Stock. In connection with the redemption of the Series H Preferred Stock, the Series H Preferred Units held by the Company were redeemed by the Operating Partnership. On March 30, 2017 , the Company redeemed all 4,000,000 shares of its 6.875% Series G Preferred Stock. For each share of Series G Preferred Stock that was outstanding, the Company had an equivalent number of 6.875% Series G Preferred Units (“Series G Preferred Units”) outstanding with substantially similar terms as the Series G Preferred Stock. In connection with the redemption of the Series G Preferred Stock, the Series G Preferred Units held by the Company were redeemed by the Operating Partnership. In connection with the redemption of the Series G and Series H Preferred Stock, during the year ended December 31, 2017 we recorded non-cash charges of $7.6 million

Share-Based and Other Compensat

Share-Based and Other Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Share-Based and Other Compensation	Share-Based and Other Compensation Stockholder Approved Share-Based Incentive Compensation Plan As of December 31, 2019 , we maintained one share-based incentive compensation plan, the Kilroy Realty 2006 Incentive Award Plan, as amended (the “2006 Plan”). The Company has a currently effective registration statement registering 9.2 million shares of our common stock for possible issuance under our 2006 Incentive Award Plan. As of December 31, 2019 , approximately 0.4 million shares were available for grant under the 2006 Plan. The calculation of shares available for grant is presented after taking into account a reserve for a sufficient number of shares to cover the vesting and payment of 2006 Plan awards that were outstanding on that date, including performance-based vesting awards at (i) levels actually achieved for the performance conditions (as defined below) for which the performance period has been completed and (ii) at maximum levels for the other performance and market conditions (as defined below) for awards still in a performance period. The Executive Compensation Committee (the “Compensation Committee”) of the Company’s Board of Directors may grant the following share-based awards to eligible individuals, as provided under the 2006 Plan: incentive stock options, nonqualified stock options, restricted stock (nonvested shares), stock appreciation rights, performance shares, performance stock units, dividend equivalents, stock payments, deferred stock, restricted stock units (“RSUs”), profit interest units, performance bonus awards, performance-based awards and other incentive awards. For each award granted under our share-based incentive compensation programs, the Operating Partnership simultaneously issues to the Company a number of common units equal to the number of shares of common stock ultimately paid by the Company in respect of such awards. 2019, 2018 and 2017 Share-Based Compensation Grants In February 2019 , the Executive Compensation Committee of the Company’s Board of Directors awarded 288,378 restricted stock units (“RSUs”) to certain officers of the Company under the 2006 Plan, which included 143,396 RSUs (at the target level of performance) that are subject to market and/or performance-based vesting requirements (the “2019 Performance-Based RSUs”) and 144,982 RSUs that are subject to time-based vesting requirements (the “2019 Time-Based RSUs”). During the year ended December 31, 2019 , 10,733 2019 Time-Based RSUs, 24,353 2019 Performance-Based RSUs and 98,844 time vest and performance RSUs that were granted in prior years were forfeited. In connection with entering into an amended employment agreement (the “Amended Employment Agreement”), on December 27, 2018, the Compensation Committee of the Company’s Board of Directors awarded John Kilroy, the Chairman of the Board of Directors, President and Chief Executive Officer of the Company and the Operating Partnership 483,871 RSUs, providing an additional retention incentive during the term of the agreement and enticing Mr. Kilroy to delay his retirement. Of these RSUs awarded, 266,130 RSUs (at the target level of performance) are subject to market-based vesting requirements and 217,741 RSUs are subject to time-based vesting requirements. In addition to Mr. Kilroy’s award, the Compensation Committee of the Company’s Board of Directors awarded 161,290 RSUs to certain members of management. Of these RSUs awarded, 80,647 RSUs (at the target level of performance) are subject to market-based vesting requirements (together totaling 346,777 target RSUs with Mr. Kilroy’s award, the “December 2018 Market-Based RSUs”) and 80,643 RSUs are subject to time-based vesting requirements (together totaling 298,384 RSUs with Mr. Kilroy’s award, the “December 2018 Time-Based RSUs”). In January and February 2018 , the Executive Compensation Committee of the Company’s Board of Directors awarded 282,038 RSUs to certain officers of the Company under the 2006 Plan, which included 158,205 RSUs (at the target level of performance) that are subject to market and/or performance-based vesting requirements (the “2018 Performance-Based RSUs”) and 123,833 RSUs that are subject to time-based vesting requirements (the “2018 Time-Based RSUs”). Additionally, during 2018, 14,999 RSUs were granted to the board of directors and certain members of management subject to time vesting requirements. In February 2017 , the Executive Compensation Committee of the Company’s Board of Directors awarded 229,976 RSUs to certain officers of the Company under the 2006 Plan, which included 130,956 RSUs (at the target level of performance) that are subject to time-based, market-measure based and performance-based vesting requirements (the “2017 Performance-Based RSUs”) and 99,020 RSUs that are subject to time-based vesting requirements (the “2017 Time-Based RSUs”). Additionally, during 2017, 43,081 RSUs were granted to the board of directors and certain members of management subject to time vesting requirements. December 2018 Market-Based RSU Grant Between 0% and 200% of the total 346,777 target number of December 2018 Market-Based RSUs will be eligible to vest based on the Company’s relative total shareholder return (“TSR”) versus a comparative group of companies that consist of companies in the SNL US REIT Office Index over the performance period. An initial number of RSUs (the “Initial Number of RSUs”) will be determined at the end of 2021 based on a three year performance period (2019 through 2021). Once the Initial Number of RSUs is determined, 75% of the Initial Number of RSUs will be scheduled to vest on January 5, 2022. The remaining 25% of the Initial Number of RSUs will be scheduled to vest on January 5, 2023, subject to adjustment based on the Company’s relative TSR for the entire four-year performance period (2019 through 2022). The December 2018 Market-Based RSUs are also subject to service vesting requirements through the scheduled vest dates. Each December 2018 Market-Based RSU represents the right to receive one share of our common stock in the future, subject to, and as modified by, the Company’s level of achievement of the applicable market conditions. The December 27, 2018 grant date fair value of the December 2018 Market-Based RSUs was $23.8 million . The fair value was calculated using a Monte Carlo simulation pricing model based on the assumptions in the table below. For the year ended December 31, 2018 , we recorded compensation expense based upon the $68.66 grant date fair value per share. Compensation expense for the December 2018 Market-Based RSUs is recognized using a graded vesting approach, where 75% of the fair value will be recognized on a straight-line basis over the three-year initial performance period through the end of 2021, and the remaining 25% of the fair value will be recognized on a straight-line basis over the four-year final performance period through the end of 2022. The following table summarizes the assumptions utilized in the Monte Carlo simulation pricing models: December 2018 Market-Based RSU Award Fair Value Assumptions Valuation date December 27, 2018 Fair value per share on valuation date $68.66 Expected share price volatility 23.0% Risk-free interest rate 2.4% The computation of expected volatility was based on a blend of the historical volatility of our shares of common stock over a period of twice the performance period and implied volatility data based on the observed pricing of six month publicly-traded options on shares of our common stock. The risk-free interest rate was based on the yield curve on zero-coupon U.S. Treasury STRIP securities in effect at December 27, 2018. 2019, 2018 and 2017 Annual Performance-Based RSU Grants The 2019 Performance-Based RSUs are scheduled to vest at the end of a three year period (consisting of calendar years 2019-2021). A target number of 2019 Performance-Based RSUs were awarded, and the final number of 2019 Performance-Based RSUs that vest (which may be more or less than the target number) will be based upon (1) the achievement of pre-set FFO per share goals for the year ending December 31, 2019 that applies to 100% of the Performance-Based RSUs awarded (the “2019 FFO Performance Condition”) and (2) a performance measure that applies to 50% of the award based upon a measure of the Company’s average debt to EBITDA ratio for the three year performance period (the “2019 Debt to EBITDA Ratio Performance Condition”) and a market measure that applies to the other 50% of the award based upon the relative ranking of the Company’s total stockholder return for the three year performance period compared to the total stockholder returns of an established comparison group of companies over the same period (the “2019 Market Condition”). The 2019 Performance-Based RSUs are also subject to a three year service vesting provision (the “service vesting condition”) and are scheduled to cliff vest on the date the final vesting percentage is determined following the end of the three year performance period under the awards. The 2019 FFO Performance Condition was achieved at 175% of target for one participant and 150% of target for all other participants. The number of 2019 Performance-Based RSUs ultimately earned could fluctuate from the target number of 2019 Performance-Based RSUs granted based upon the levels of achievement for the 2019 Debt to EBITDA Ratio Performance Condition, the 2019 Market Condition, and the extent to which the service vesting condition is satisfied. The estimate of the number of 2019 Performance-Based RSUs earned is evaluated quarterly during the performance period based on our estimate for each of the performance conditions measured against the applicable goals. Compensation expense for the 2019 Performance-Based RSU grant is recognized on a straight-line basis over the requisite service period for each participant, which is generally the three year service period. The 2018 Performance-Based RSUs are scheduled to vest at the end of a three year period (consisting of calendar years 2018-2020). A target number of 2018 Performance-Based RSUs were awarded, and the final number of 2018 Performance-Based RSUs that vest (which may be more or less than the target number) will be based upon (1) the achievement of pre-set FFO per share goals for the year ending December 31, 2018 that applies to 100% of the Performance-Based RSUs awarded (the “2018 FFO Performance Condition”) and (2) a performance measure that applies to 50% of the award based upon a measure of the Company’s average debt to EBITDA ratio for the three year performance period (the “2018 Debt to EBITDA Ratio Performance Condition” and together with the 2018 FFO Performance Condition, the “2018 Performance Conditions”) and a market measure that applies to the other 50% of the award based upon the relative ranking of the Company’s TSR for the three year performance period compared to the TSR of an established comparison group of companies over the same period (the “2018 Market Condition”). The 2018 Performance-Based RSUs are also subject to a three year service vesting provision and are scheduled to cliff vest on the date the final vesting percentage is determined following the end of the three year performance period under the awards. The 2018 FFO Performance Condition was achieved at 175% of target for one participant and 150% of target for all other participants. The number of 2018 Performance-Based RSUs ultimately earned could fluctuate from the current estimated number of 2018 Performance-Based RSUs granted based upon the levels of achievement for the 2018 Debt to EBITDA Ratio Performance Condition, the 2018 Market Condition and the extent to which the service vesting condition is satisfied. The 2017 Performance-Based RSUs are scheduled to cliff vest at the end of a three year period (consisting of calendar years 2017-2019) based upon (1) the achievement of pre-defined FFO per share goals for the year ended December 31, 2017 that applies to 100% of the 2017 Performance-Based RSUs awarded (the “2017 FFO Performance Condition”) and (2) also based upon either the average FAD per share growth that applies to 30% of the award or the Company’s average debt to EBITDA ratio that applies to a separate 30% of the award (together, the “Other 2017 Performance Conditions” and together with the 2017 FFO Performance Condition, the “2017 Performance Conditions”) or the relative TSR versus a comparative group of companies that consist of companies in the SNL US REIT Office Index that applies to the remaining 40% of the award (the “2017 Market Condition”) for the three year period ending December 31, 2019. Based on the combined results of the 2017 Performance Conditions and the 2017 Market Condition, the 2017 Performance-Based RSUs achieved a weighted average of approximately 131% of their target level of performance. As of December 31, 2019 , the estimated number of RSUs earned for the 2019 and 2018 Performance-Based RSUs and the actual number of RSUs earned for the 2017 Performance-Based RSUs was as follows: 2019 Performance-Based RSUs 2018 Performance-Based RSUs 2017 Performance-Based RSUs Service vesting period February 1, 2019 - January, 2022 February 14, 2018 - January, 2021 February 24, 2017 - January, 2020 Target RSUs granted 143,396 158,205 130,956 Estimated RSUs earned (1) 229,095 262,242 142,581 Date of valuation February 1, 2019 February 14, 2018 February 24, 2017 _______________ (1) Estimated RSUs earned for the 2019 Performance-Based RSUs are based on the actual achievement of the 2019 FFO Performance Condition and for the 2019 Debt to EBITDA Ratio Performance Condition, assumes 125% of the target level of achievement for one participant and 117% of the target level of achievement for all other participants, and target level of achievement of the 2019 Market Condition. Estimated RSUs earned for the 2018 Performance-Based RSUs are based on the actual achievement of the 2018 FFO Performance Condition and assume target level achievement of the 2018 Market Condition and maximum level of achievement of the 2018 Debt to EBITDA Ratio Performance Condition. The 2017 Performance-Based RSUs earned are based on actual performance of the 2017 Performance Conditions and the 2017 Market Condition. Each Performance-Based RSU represents the right to receive one share of our common stock in the future, subject to, and as modified by, the Company’s level of achievement of the applicable performance and market conditions. The fair values of the 2019 Performance-Based RSUs, 2018 Performance-Based RSUs and 2017 Performance-Based RSUs were $10.2 million at February 1, 2019 , $10.8 million at February 14, 2018 , and $10.3 million at February 24, 2017 , respectively. The fair values for the awards with market conditions were calculated using a Monte Carlo simulation pricing model based on the assumptions in the table below. The determination of the fair value of the 2019, 2018 and 2017 Performance-Based RSUs takes into consideration the likelihood of achievement of the 2019, 2018 and 2017 Performance Conditions and the 2019, 2018 and 2017 Market Conditions, respectively, as discussed above. The following table summarizes the assumptions utilized in the Monte Carlo simulation pricing models: 2019 Award Fair Value Assumptions 2018 Award Fair Value Assumptions 2017 Award Fair Value Assumptions Valuation date February 1, 2019 February 14, 2018 February 24, 2017 Fair value per share on valuation date $72.57 $70.08 $80.89 Expected share price volatility 19.0% 20.0% 21.0% Risk-free interest rate 2.48% 2.37% 1.39% The computation of expected volatility was based on a blend of the historical volatility of our shares of common stock over a period of twice the remaining performance period as of the grant date and implied volatility data based on the observed pricing of six month publicly-traded options on shares of our common stock. The risk-free interest rate was based on the yield curve on zero-coupon U.S. Treasury STRIP securities in effect at February 1, 2019 , February 14, 2018 , and February 24, 2017 . Compensation expense for the Performance-Based RSUs is recognized on a straight-line basis over the requisite service period for each participant, which is generally the three-year service period. As of December 31, 2019 , the number of 2019 Performance-Based RSUs estimated to be earned based on the Company’s estimate of the performance conditions measured against the applicable goals was 229,095 , and the compensation cost recorded to date for this program was based on that estimate. For the portion of the 2019 Performance-Based RSUs subject to the 2019 Market Condition, for the year ended December 31, 2019 , we recorded compensation expense based upon the $72.57 fair value per share at February 1, 2019 . Compensation expense will be variable for the portion of the 2019 Performance-Based RSUs subject to the 2019 Debt to EBITDA Ratio Performance Condition, based upon the outcome of that condition. As of December 31, 2019 , the number of 2018 Performance-Based RSUs estimated to be earned based on the Company’s estimate of the performance conditions measured against the applicable goals was 262,242 , and the compensation cost recorded to date for this program was based on that estimate. For the portion of the 2018 Performance-Based RSUs subject to the 2018 Market Condition, for the years ended December 31, 2019 and 2018 , we recorded compensation expense based upon the $70.08 fair value per share at February 14, 2018 . Compensation expense will be variable for the portion of the 2018 Performance-Based RSUs subject to the 2018 Debt to EBITDA Performance Condition, based upon the outcome of that condition. For the years ended December 31, 2019 , 2018 and 2017 , we recorded compensation expense for the portion of the 2017 Performance-Based RSUs subject to the 2017 Market Condition based upon the $80.89 fair value per share at February 24, 2017 and for the portion of the 2017 Performance-Based RSUs subject to the 2017 Debt to EBITDA Ratio Performance Condition, based on the stock price at date of grant multiplied by the 142,581 RSUs, which is net of forfeitures, estimated to be earned at December 31, 2019 . Annual 2019, 2018 and 2017 and December 2018 Time-Based RSU Grants The annual 2019, 2018 and 2017 Time-Based RSUs are scheduled to vest in equal installments over the periods listed below. The 2019 Time-Based RSUs are scheduled to vest in three equal annual installments beginning on January 5, 2020 through January 5, 2022. The December 2018 Time-Based RSUs are scheduled to vest 50% on January 5, 2022 and 50% on January 5, 2023. Compensation expense for the December 2018 and annual 2019, 2018 and 2017 Time-Based RSUs is recognized on a straight-line basis over the requisite service period, which is generally the explicit service period. However, for one participant there was a shorter service period for their 2017 and 2018 Time-Based RSUs. Each Time-Based RSU represents the right to receive one share of our common stock in the future, subject to continued employment through the applicable vesting date. The total fair value of the Time-Based RSUs is based on the Company's closing share price on the NYSE on the respective fair valuation dates as detailed in the table below: 2019 Time-Based RSU Grant December 2018 Time-Based RSU Grant 2018 Time-Based RSU Grant (1) 2017 Time-Based RSU Grant (2) Service vesting period February 1, 2019 - January 5, 2022 December 27, 2018 - January 5, 2023 January & February 2018 - January 5, 2021 February 2017 - January 5, 2020 Fair value on valuation date (in millions) $ 10.1 $ 18.5 $ 8.4 $ 7.5 Fair value per share $ 69.89 $ 62.00 $ 70.37 $ 73.30 Date of fair valuation February 1, 2019 December 27, 2018 January & February 2018 February 2017 _______________ (1) The 2018 Time-Based RSUs consist of 56,015 RSUs granted on January 29, 2018 at a fair value per share of $70.37 and 67,818 RSUs granted on February 14, 2018 at a fair value per share of $66.46 . (2) The 2017 Time-Based RSUs consist of 41,119 RSUs granted on February 3, 2017 at a fair value per share of $73.30 and 57,901 RSUs granted on February 24, 2017 at a fair value per share of $77.16 . Summary of Performance and Market-Measure Based RSUs A summary of our performance and market-measure based RSU activity from January 1, 2019 through December 31, 2019 is presented below: Nonvested RSUs Vested RSUs Total RSUs Amount Weighted-Average Outstanding at January 1, 2019 1,018,337 $ 67.29 35,761 1,054,098 Granted 231,191 71.12 1,155 232,346 Vested (261,990 ) 57.08 261,990 — Settled (1) — (264,814 ) (264,814 ) Issuance of dividend equivalents (2) 23,254 74.11 2,592 25,846 Forfeited (78,117 ) 70.07 (5 ) (78,122 ) Outstanding as of December 31, 2019 (3) 932,675 $ 71.04 36,679 969,354 _______________ (1) Represents vested RSUs that were settled in shares of the Company’s common stock. Total shares settled include 125,220 shares that were tendered in accordance with the terms of the 2006 Plan to satisfy minimum statutory tax withholding requirements related to the RSUs settled. We accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy tax obligations. (2) Represents the issuance of dividend equivalents earned on the underlying RSUs. The dividend equivalents vest based on terms specified under the related RSU award agreement. (3) Outstanding RSUs as of December 31, 2019 represent the actual achievement of the FFO performance conditions and assumes target levels for the market and other performance conditions. The number of restricted stock units ultimately earned is subject to change based upon actual performance over the three-year vesting period. Dividend equivalents earned will vest along with the underlying award and are also subject to changes based on the number of RSUs ultimately earned for each underlying award. A summary of our performance and market-measure based RSU activity for the years ended December 31, 2019 , 2018 and 2017 is presented below: RSUs Granted RSUs Vested Years ended December 31, Non-Vested RSUs Granted (1) Weighted-Average Fair Value Per Share Vested RSUs Total Vest-Date Fair Value (in thousands) 2019 231,191 $ 71.12 (265,737 ) $ 18,703 2018 601,012 68.51 (265,918 ) 18,906 2017 170,994 78.97 (194,991 ) 14,270 _______________ (1) Non-vested RSUs granted are based on the actual achievement of the FFO performance conditions and assumes target level achievement for the market and other performance conditions. Summary of Time-Based RSUs A summary of our time-based RSU activity from January 1, 2019 through December 31, 2019 is presented below: Nonvested RSUs Vested RSUs Total RSUs Amount Weighted Average Fair Value Outstanding at January 1, 2019 586,779 $ 65.87 1,089,088 1,675,867 Granted 153,005 70.31 — 153,005 Vested (153,464 ) 67.26 153,464 — Settled (1) (198,183 ) (198,183 ) Issuance of dividend equivalents (2) 13,341 74.72 28,755 42,096 Forfeited (55,813 ) 68.71 — (55,813 ) Canceled (3) (1,746 ) (1,746 ) Outstanding as of December 31, 2019 543,848 $ 66.66 1,071,378 1,615,226 _______________ (1) Represents vested RSUs that were settled in shares of the Company’s common stock. Total shares settled include 82,646 shares that were tendered in accordance with the terms of the 2006 Plan to satisfy minimum statutory tax withholding requirements related to the RSUs settled. We accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy tax obligations. (2) Represents the issuance of dividend equivalents earned on the underlying RSUs. The dividend equivalents vest based on terms specified under the related RSU award agreement. (3) For shares vested but not yet settled, we accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy minimum statutory tax-withholding requirements related to either the settlement or vesting of RSUs in accordance with the terms of the 2006 Plan. A summary of our time-based RSU activity for the years ended December 31, 2019 , 2018 and 2017 is presented below: RSUs Granted RSUs Vested Year ended December 31, Non-Vested RSUs Issued Weighted-Average Grant Date Fair Value Per Share Vested RSUs Total Vest-Date Fair Value (1) (in thousands) 2019 153,005 $ 70.31 (182,219 ) $ 12,277 2018 437,216 64.21 (214,131 ) 14,768 2017 142,101 74.91 (228,095 ) 16,735 _______________ (1) Total fair value of RSUs vested was calculated based on the quoted closing share price of the Company’s common stock on the NYSE on the day of vesting. Excludes the issuance of dividend equivalents earned on the underlying RSUs. The dividend equivalents vest based on terms specified under the related RSU award agreement. Summary of Nonvested Restricted Stock We did not have any nonvested restricted stock at January 1, 2019 or December 31, 2019 . A summary of our nonvested and vested restricted stock activity for years ended December 31, 2018 and 2017 is presented below: Shares Granted Shares Vested Years ended December 31, Nonvested Shares Issued Weighted-Average Grant Date Fair Value Per Share Vested Shares Total Fair Value at Vest Date (1) (in thousands) 2018 — — (22,884 ) 1,652 2017 — — (24,261 ) 1,781 _______________ (1) Total fair value of shares vested was calculated based on the quoted closing share price of the Company’s common stock on the NYSE on the date of vesting. Share-Based Compensation Cost Recorded During the Period The total compensation cost for all share-based compensation programs was $32.8 million , $35.9 million and $26.3 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Of the total share-based compensation costs, $5.8 million , $8.0 million and $7.3 million was capitalized as part of real estate assets and for 2018 and 2017, deferred leasing costs, for the years ended December 31, 2019 , 2018 and 2017 , respectively. As of December 31, 2019 , there was approximately $50.5 million of total unrecognized compensation cost related to nonvested incentive awards granted under share-based compensation arrangements that is expected to be recognized over a weighted-average period of 2.1 years. The remaining compensation cost related to these nonvested incentive awards had been recognized in periods prior to December 31, 2019 . The $50.5 million of unrecognized compensation costs does not reflect the future compensation cost related to share-based awards that were granted subsequent to December 31, 2019 . Other Compensation On December 27, 2018, the Executive Compensation Committee of the Company’s Board approved, and the Company and the Operating Partnership entered into the Amended Employment Agreement with John Kilroy, which amends and supersedes the existing employment agreement dated January 1, 2012. Except as noted below, the Amended Employment Agreement continues Mr. Kilroy’s employment on terms substantially similar to those of the existing employment agreement, with a new term scheduled to continue through December 31, 2023. The Amended Employment Agreement includes a cash retirement benefit of $13.2 million , or $16.2 million for a retirement at or after attaining age 73 , with at least twelve months’ advance notice or at or after the end of the term of the agreement. For the year ended December 31, 2018 , the Company recognized $12.1 million of compensation expense in general and administrative expenses on the consolidated statement of operations, representing the present value of the potential cash retirement benefit amount that was earned based on prior service. For the year ended December 31, 2019 , the Company recognized $1.5 million

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans 401(k) Plan We have a retirement savings plan designed to qualify under Section 401(k) of the Code (the “401(k) Plan”). Our employees are eligible to participate in the 401(k) Plan on the first day of the month after three months of service. The 401(k) Plan allows eligible employees (“401(k) Participants”) to defer up to 60% of their eligible compensation on a pre-tax basis, subject to certain maximum amounts allowed by the Code. The 401(k) Plan provides for a matching contribution by the Company in an amount equal to 50 cents of each one dollar of participant contributions up to a maximum of 10% of the 401(k) Participant’s annual salary. 401(k) Participants vest immediately in the amounts contributed by us. For each of the years ended December 31, 2019 , 2018 , and 2017 , we contributed $1.6 million , $1.5 million and $1.3 million , respectively, to the 401(k) Plan. Deferred Compensation Plan In 2007, we adopted the Deferred Compensation Plan, under which directors and certain management employees may defer receipt of their compensation, including up to 70% of their salaries and up to 100% of their director fees and bonuses, as applicable. In addition, employee participants will receive mandatory Company contributions to their Deferred Compensation Plan accounts equal to 10% of their gross monthly salaries, without regard to whether such employees elect to defer salary or bonus compensation under the Deferred Compensation Plan. Our Board may, but has no obligation to, approve additional discretionary contributions by the Company to Participant accounts. We hold the Deferred Compensation Plan assets in a limited rabbi trust, which is subject to the claims of our creditors in the event of bankruptcy or insolvency. See Note 19 “Fair Value Measurements and Disclosures” for further discussion of our Deferred Compensation Plan assets as of December 31, 2019 and 2018 . Our liability of $27.0 million and $21.7 million under the Deferred Compensation Plan was fully funded as of December 31, 2019 and 2018 , respectively.

Future Minimum Rent

Future Minimum Rent	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Future Minimum Rent	Future Minimum Rent We have operating leases with tenants that expire at various dates through 2043 and are either subject to scheduled fixed increases or adjustments in rent based on the Consumer Price Index. Generally, the leases grant tenants renewal options. Leases also provide for additional rents based on certain operating expenses. Future contractual minimum rent under operating leases as of December 31, 2019 for future periods is summarized as follows: Year Ending (in thousands) 2020 $ 675,636 2021 728,736 2022 785,239 2023 769,294 2024 727,399 Thereafter 4,054,487 Total (1) $ 7,740,791 ______________ (1) Excludes residential leases and leases with a term of one year or less. Future contractual minimum rent under operating leases as of December 31, 2018 for future periods is summarized as follows: Year Ending (in thousands) 2019 $ 566,783 2020 632,875 2021 631,835 2022 620,684 2023 586,371 Thereafter 3,240,143 Total (1) $ 6,278,691 ______________ (1) Excludes residential leases and leases with a term of one year or less.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies General As of December 31, 2019 , we had commitments of approximately $1.0 billion , excluding our ground lease commitments, for contracts and executed leases directly related to our operating and development properties. Ground Leases The following table summarizes our properties that are held subject to long-term noncancellable ground lease obligations and the respective contractual expiration dates: Property Contractual Expiration Date (1) 601 108th Ave NE, Bellevue, WA November 2093 701, 801 and 837 N. 34th Street, Seattle, WA (2) December 2041 1701 Page Mill Road and 3150 Porter Drive, Palo Alto, CA December 2067 Kilroy Airport Center Phases I, II, and III, Long Beach, CA July 2084 3243 S. La Cienega Boulevard, Los Angeles, CA (3) October 2106 ____________________ (1) Reflects the contractual expiration date prior to the impact of any extension or purchase options held by the Company. (2) The Company has three 10 -year and one 45 -year extension options for this ground lease, which if exercised would extend the expiration date to December 2116. (3) We entered into this ground lease in connection with an operating property acquisition in 2019. Refer to Note 3 “Acquisitions” for additional information. As of December 31, 2019 , the weighted average remaining lease term of our ground leases is 55 years . For the year ended December 31, 2019 , variable lease costs totaling $2.9 million , were recorded to ground leases expense on our consolidated statements of operations. The minimum commitment under our ground leases as of December 31, 2019 for five years and thereafter is as follows: Year Ending (in thousands) 2020 5,641 2021 5,641 2022 5,642 2023 5,662 2024 5,662 Thereafter 286,385 Total undiscounted cash flows (1)(2)(3)(4)(5)(6) $ 314,633 Present value discount (216,233 ) Ground lease liabilities $ 98,400 ________________________ (1) Excludes contingent future rent payments based on gross income or adjusted gross income and reflects the minimum ground lease obligations before the impact of ground lease extension options. (2) One of our ground lease obligations is subject to a fair market value adjustment every five years ; however, the lease includes ground rent subprotection and infrastructure rent credits which currently limit our annual rental obligations to $1.0 million . The contractual obligations for that ground lease included above assumes the lesser of $1.0 million or annual lease rental obligation in effect as of December 31, 2019 . (3) One of our ground lease obligations includes a component which is based on the percentage of gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every five years based on 50% of the average annual percentage rent for the previous five years. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2019 for the remainder of the lease term since we cannot predict future adjustments. (4) One of our ground lease obligations is subject to a fair market value adjustment every five years based on a combination of CPI adjustments and third-party appraisals limited to maximum increases annually. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2019 for the remainder of the lease term since we cannot predict future adjustments. (5) One of our ground lease obligations includes a component which is based on the percentage of adjusted gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every 10 years by an amount equal to 60% of the average annual percentage rent for the previous three years. The contractual obligations for this lease included above assume the current annual ground lease obligation in effect at December 31, 2019 for the remainder of the lease term since we cannot predict future adjustments. (6) One of our ground lease obligations is subject to fixed 5% ground rent increases every five years , with the next increase occurring on December 1, 2022. The minimum commitment under our ground leases as of December 31, 2018 for future periods is summarized as follows: Year Ending (in thousands) 2019 $ 5,154 2020 5,154 2021 5,154 2022 5,154 2023 5,154 Thereafter 233,619 Total (1)(2)(3)(4)(5) $ 259,389 ________________________ (1) Excludes contingent future rent payments based on gross income or adjusted gross income and reflects the minimum ground lease obligations before the impact of ground lease extension options. (2) One of our ground lease obligations is subject to a fair market value adjustment every five years ; however, the lease includes ground rent subprotection and infrastructure rent credits which currently limit our annual rental obligations to $1.0 million . The contractual obligations for that ground lease included above assumes the lesser of $1.0 million or annual lease rental obligation in effect as of December 31, 2018. (3) One of our ground lease obligations includes a component which is based on the percentage of gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every five years based on 50% of the average annual percentage rent for the previous five years. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2018 for the remainder of the lease term since we cannot predict future adjustments. (4) One of our ground lease obligations is subject to a fair market value adjustment every five years based on a combination of CPI adjustments and third-party appraisals limited to maximum increases annually. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2018 for the remainder of the lease term since we cannot predict future adjustments. (5) One of our ground lease obligations includes a component which is based on the percentage of adjusted gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every ten years by an amount equal to 60% of the average annual percentage rent for the previous three years. The contractual obligations for this lease included above assume the current annual ground lease obligation in effect at December 31, 2018 for the remainder of the lease term since we cannot predict future adjustments. Environmental Matters We follow the policy of monitoring all of our properties, including acquisition, development, and existing stabilized portfolio properties, for the presence of hazardous or toxic substances. While there can be no assurance that a material environmental liability does not exist, we are not currently aware of any environmental liability with respect to our stabilized portfolio properties that would have a material adverse effect on our financial condition, results of operations and cash flow, or that we believe would require additional disclosure or the recording of a loss contingency. As of December 31, 2019 and 2018 , we had accrued environmental remediation liabilities of approximately $80.7 million and $83.2 million , respectively, recorded on our consolidated balance sheets in connection with certain of our in-process and future development projects. The accrued environmental remediation liabilities represent the remaining costs we estimate we will incur prior to and during the development process at various development acquisition sites. These estimates, which we developed with the assistance of third party experts, consist primarily of the removal of contaminated soil, performing environmental closure activities, constructing remedial systems, and other related costs since we are required to dispose of any existing contaminated soil, and sometimes perform other environmental closure or remedial activities, when we develop new buildings at these sites. We record estimated environmental remediation obligations for acquired properties at the acquisition date when we are aware of such costs and when such costs are probable of being incurred and can be reasonably estimated. Estimated costs related to development environmental remediation liabilities are recorded as an increase to the cost of the development project. Actual costs are recorded as a decrease to the liability when incurred. These accruals are adjusted as an increase or decrease to the development project costs and as an increase or decrease to the accrued environmental remediation liability if we obtain further information or circumstances change. The environmental remediation obligations recorded at December 31, 2019 and 2018 were not discounted to their present values since the amount and timing of cash payments are not fixed. It is possible that we could incur additional environmental remediation costs in connection with these development projects. However, potential additional environmental costs for these development projects cannot be reasonably estimated at this time and certain changes in estimates could occur as the site conditions, final project timing, design elements, actual soil conditions and other aspects of the projects, which may depend upon municipal and other approvals beyond the control of the Company, are determined. Other than the accrued environmental liabilities discussed above, we are not aware of any unasserted claims and assessments with respect to an environmental liability that we believe would require additional disclosure or the recording of an additional loss contingency. Litigation We and our properties are subject to litigation arising in the ordinary course of business. To our knowledge, neither we nor any of our properties are presently subject to any litigation or threat of litigation which, if determined unfavorably to us, would have a material adverse effect on our cash flow, financial condition, or results of operations. Insurance

Fair Value Measurements and Dis

Fair Value Measurements and Disclosures	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements and Disclosures	Fair Value Measurements and Disclosures Assets and Liabilities Reported at Fair Value The only assets we record at fair value on our consolidated financial statements are the marketable securities related to our Deferred Compensation Plan (see Note 16 “Employee Benefit Plans” for additional information). The following table sets forth the fair value of our marketable securities as of December 31, 2019 and 2018 : Fair Value (Level 1) (1) 2019 2018 Description (in thousands) Marketable securities (2) $ 27,098 $ 21,779 _______________ (1) Based on quoted prices in active markets for identical securities. (2) The marketable securities are held in a limited rabbi trust . We report the change in the fair value of the marketable securities at the end of each accounting period in interest income and other net investment (losses) gains in the consolidated statements of operations. We also adjust the related Deferred Compensation Plan liability to fair value at the end of each accounting period based on the performance of the benchmark funds selected by each participant, which results in a corresponding increase or decrease to compensation cost for the period. The following table sets forth the net (loss) gain on marketable securities recorded during the years ended December 31, 2019 , 2018 and 2017 : December 31, 2019 2018 2017 Description (in thousands) Net gain (loss) on marketable securities $ 3,885 $ (1,851 ) $ 3,023 Financial Instruments Disclosed at Fair Value The following table sets forth the carrying value and the fair value of our other financial instruments as of December 31, 2019 and 2018 : December 31, 2019 2018 Carrying Value Fair Value (1) Carrying Value Fair Value (1) (in thousands) Liabilities Secured debt, net $ 258,593 $ 272,997 $ 335,531 $ 335,885 Unsecured debt, net 3,049,185 3,252,217 2,552,070 2,546,386 Unsecured line of credit 245,000 245,195 45,000 45,058 _______________ (1) Fair value calculated using Level II inputs, which are based on model-derived valuations in which significant inputs and significant value drivers are observable in active markets.

Other Significant Events

Other Significant Events	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Other Significant Events	Receivables Current Receivables, net Current receivables, net is primarily comprised of contractual rents and other lease-related obligations due from tenants. The balance consisted of the following as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Current receivables $ 27,660 $ 24,815 Allowance for uncollectible tenant receivables (1) (1,171 ) (4,639 ) Current receivables, net $ 26,489 $ 20,176 _______________ (1) Refer to Note 2 “Basis of Presentation and Significant Accounting Policies” for discussion of our accounting policies related to the allowance for uncollectible tenant receivables and Note 20 “Other Significant Transactions” for additional information regarding changes in our allowance for uncollectible tenant receivables. Deferred Rent Receivables, net Deferred rent receivables, net consisted of the following as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Deferred rent receivables $ 339,489 $ 270,346 Allowance for deferred rent receivables (1) (1,552 ) (3,339 ) Deferred rent receivables, net $ 337,937 $ 267,007 _______________ (1) During the year ended December 31, 2019 , we recorded a $2.9 million net increase in rental income on our consolidated statements of operations primarily due to a $4.2 million increase in revenue related to the improved credit quality of a tenant for which we previously recorded a bad debt reserve during the year ended December 31, 2018 , partially offset by a $1.3 million decrease in revenue for other tenants with diminished credit quality during the year ended December 31, 2019 . During the year ended December 31, 2018 , we recognized $5.7 million of provision for bad debts. The provision for bad debts was primarily due to a $7.0 million provision for one tenant recognized during the second quarter of 2018, partially offset by a $1.4 million decrease in the provision for bad debts for one lease due to the assignment of the lease to a credit tenant during the second quarter of 2018.

Net Income Available to Common

Net Income Available to Common Stockholders Per Share of the Company	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Income Available to Common Stockholders Per Share of the Company	Net Income Available to Common Stockholders Per Share of the Company The following table reconciles the numerator and denominator in computing the Company’s basic and diluted per-share computations for net income available to common stockholders for the years ended December 31, 2019 , 2018 and 2017 : Year Ended December 31, 2019 2018 2017 (in thousands, except unit and per unit amounts) Numerator: Net income attributable to Kilroy Realty Corporation $ 195,443 $ 258,415 $ 164,612 Total preferred dividends — — (13,363 ) Allocation to participating securities (1) (2,119 ) (2,004 ) (1,975 ) Numerator for basic and diluted net income available to common stockholders $ 193,324 $ 256,411 $ 149,274 Denominator: Basic weighted average vested shares outstanding 103,200,568 99,972,359 98,113,561 Effect of dilutive securities 648,600 510,006 613,770 Diluted weighted average vested shares and common stock equivalents outstanding 103,849,168 100,482,365 98,727,331 Basic earnings per share: Net income available to common stockholders per share $ 1.87 $ 2.56 $ 1.52 Diluted earnings per share: Net income available to common stockholders per share $ 1.86 $ 2.55 $ 1.51 ________________________ (1) Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs. Share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are considered participating securities. The impact of potentially dilutive common shares, including stock options, RSUs, shares issuable under executed forward equity sale agreements and other securities are considered in our diluted earnings per share calculation for the years ended December 31, 2019 , 2018 , and 2017 . Certain market measure-based RSUs are not included in dilutive securities as of December 31, 2019 , 2018 , and 2017 as not all performance metrics had been met by the end of the applicable reporting periods.

Net Income Available to Commo_2

Net Income Available to Common Unitholders Per Unit of the Operating Partnership	12 Months Ended
	Dec. 31, 2019
Kilroy Realty L.P. [Member]
Net Income Available To Common Unitholders [Line Items]
Net Income Available to Common Unitholders per Unit of the Operating Partnership	Net Income Available to Common Unitholders Per Unit of the Operating Partnership The following table reconciles the numerator and denominator in computing the Operating Partnership’s basic and diluted per-unit computations for net income available to common unitholders for the years ended 2019 , 2018 and 2017 : Year Ended December 31, 2019 2018 2017 (in thousands, except unit and per unit amounts) Numerator: Net income attributable to Kilroy Realty, L.P. $ 198,738 $ 263,210 $ 167,440 Total preferred distributions — — (13,363 ) Allocation to participating securities (1) (2,119 ) (2,004 ) (1,975 ) Numerator for basic and diluted net income available to common unitholders $ 196,619 $ 261,206 $ 152,102 Denominator: Basic weighted average vested units outstanding 105,223,975 102,025,276 100,246,567 Effect of dilutive securities 648,600 510,006 613,770 Diluted weighted average vested units and common unit equivalents outstanding 105,872,575 102,535,282 100,860,337 Basic earnings per unit: Net income available to common unitholders per unit $ 1.87 $ 2.56 $ 1.52 Diluted earnings per unit: Net income available to common unitholders per unit $ 1.86 $ 2.55 $ 1.51 ________________________ (1) Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs. Share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are considered participating securities. The impact of potentially dilutive common units, including stock options, RSUs, shares issuable under executed forward equity sale agreements and other securities are considered in our diluted earnings per share calculation for the years ended December 31, 2019 , 2018 and 2017 . Certain market measure-based RSUs are not included in dilutive securities as of December 31, 2019 , 2018 and 2017 as not all performance metrics had been met by the end of the applicable reporting periods.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information of the Company	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information of the Company	Supplemental Cash Flow Information of the Company Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 13 and 28) $ 53,219 $ 47,559 $ 43,448 Exchange of common units of the Operating Partnership into shares of the Company’s common stock $ 78 $ 1,962 $ 10,939 The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798 Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common $ 53,219 $ 47,559 $ 43,448 The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information of the Operating Partnership	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information of the Operating Partnership	Supplemental Cash Flow Information of the Company Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 13 and 28) $ 53,219 $ 47,559 $ 43,448 Exchange of common units of the Operating Partnership into shares of the Company’s common stock $ 78 $ 1,962 $ 10,939 The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798 Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common $ 53,219 $ 47,559 $ 43,448 The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798

Tax Treatment of Distributions

Tax Treatment of Distributions	12 Months Ended
	Dec. 31, 2019
Tax Treatment of Distributions [Abstract]
Tax Treatment of Distributions	Tax Treatment of Distributions The following table reconciles the dividends declared per share of common stock to the dividends paid per share of common stock during the years ended December 31, 2019 , 2018 and 2017 as follows: Year Ended December 31, Dividends 2019 2018 2017 Dividends declared per share of common stock $ 1.910 $ 1.790 $ 1.650 Less: Dividends declared in the current year and paid in the following year (0.485 ) (0.455 ) (0.425 ) Add: Dividends declared in the prior year and paid in the current year (1) 0.455 0.425 2.275 Dividends paid per share of common stock $ 1.880 $ 1.760 $ 3.500 _________________ (1) The fourth quarter 2016 dividend of $2.275 per share of common stock consists of a special cash dividend of $1.90 per share of common stock and a regular quarterly cash dividend of $0.375 per share of common stock. The $1.90 per share special distribution is treated as paid in two tax years for income tax purposes: $1.587 is treated as paid on December 31, 2016 and $0.313 is treated as paid on January 13, 2017. The $0.375 per share regular quarterly distribution is considered a 2017 dividend distribution for income tax purposes. The unaudited income tax treatment for the dividends to common stockholders reportable for the years ended December 31, 2019 , 2018 and 2017 as identified in the table above was as follows: Year Ended December 31, Shares of Common Stock 2019 2018 2017 Ordinary income (1) $ 0.939 49.95 % $ 1.474 83.73 % $ 1.356 70.87 % Qualified dividend 0.004 0.21 0.003 0.19 0.002 0.11 Return of capital 0.312 16.62 0.275 15.64 0.344 18.00 Capital gains (2) 0.600 31.93 0.008 0.44 — — Unrecaptured section 1250 gains 0.025 1.29 — — 0.211 11.02 $ 1.880 100.00 % $ 1.760 100.00 % $ 1.913 100.00 % _________________ (1) The Tax Cuts and Jobs Act enacted on December 22, 2017 generally allows a deduction for noncorporate taxpayers equal to 20% of ordinary dividends distributed by a REIT (excluding capital gain dividends and qualified dividend income). The amount of dividend eligible for this deduction is referred to as the Section 199A Dividend. For the year ended December 31, 2019 , the Section 199A Dividend is equal to the total ordinary income dividend. (2) Capital gains are comprised entirely of 20% rate gains.

Quarterly Financial Information

Quarterly Financial Information of the Company (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information of the Company (Unaudited)	Quarterly Financial Information of the Company (Unaudited) Summarized quarterly financial data for the years ended December 31, 2019 and 2018 was as follows: 2019 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 201,202 $ 200,492 $ 215,525 $ 220,235 Net income 41,794 47,215 48,298 77,922 Net income attributable to Kilroy Realty Corporation 36,903 42,194 43,846 72,500 Net income available to common stockholders 36,903 42,194 43,846 72,500 Net income available to common stockholders per share – basic 0.36 0.41 0.41 0.68 Net income available to common stockholders per share – diluted 0.36 0.41 0.41 0.67 2018 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 182,822 $ 187,072 $ 186,562 $ 190,842 Net income 40,971 31,755 38,310 166,890 Net income attributable to Kilroy Realty Corporation 36,246 27,549 34,400 160,220 Net income available to common stockholders 36,246 27,549 34,400 160,220 Net income available to common stockholders per share – basic 0.36 0.27 0.34 1.59 Net income available to common stockholders per share – diluted 0.36 0.27 0.33 1.58 ____________________ (1) The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. For the year ended December 31, 2018

Quarterly Financial Informati_2

Quarterly Financial Information of the Operating Partnership (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information of the Operating Partnership (Unaudited)	Quarterly Financial Information of the Company (Unaudited) Summarized quarterly financial data for the years ended December 31, 2019 and 2018 was as follows: 2019 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 201,202 $ 200,492 $ 215,525 $ 220,235 Net income 41,794 47,215 48,298 77,922 Net income attributable to Kilroy Realty Corporation 36,903 42,194 43,846 72,500 Net income available to common stockholders 36,903 42,194 43,846 72,500 Net income available to common stockholders per share – basic 0.36 0.41 0.41 0.68 Net income available to common stockholders per share – diluted 0.36 0.41 0.41 0.67 2018 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 182,822 $ 187,072 $ 186,562 $ 190,842 Net income 40,971 31,755 38,310 166,890 Net income attributable to Kilroy Realty Corporation 36,246 27,549 34,400 160,220 Net income available to common stockholders 36,246 27,549 34,400 160,220 Net income available to common stockholders per share – basic 0.36 0.27 0.34 1.59 Net income available to common stockholders per share – diluted 0.36 0.27 0.33 1.58 ____________________ (1) The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. For the year ended December 31, 2018
Kilroy Realty L.P. [Member]
Quarterly Financial Information of the Operating Partnership (Unaudited)	Quarterly Financial Information of the Operating Partnership (Unaudited) Summarized quarterly financial data for the years ended December 31, 2019 and 2018 was as follows: 2019 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per unit amounts) Revenues $ 201,202 $ 200,492 $ 215,525 $ 220,235 Net income 41,794 47,215 48,298 77,922 Net income attributable to the Operating Partnership 37,508 42,901 44,589 73,740 Net income available to common unitholders 37,508 42,901 44,589 73,740 Net income available to common unitholders per unit – basic 0.36 0.41 0.41 0.68 Net income available to common unitholders per unit – diluted 0.36 0.41 0.41 0.67 2018 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per unit amounts) Revenues $ 182,822 $ 187,072 $ 186,562 $ 190,842 Net income 40,971 31,755 38,310 166,890 Net income attributable to the Operating Partnership 36,893 28,015 34,993 163,309 Net income available to common unitholders 36,893 28,015 34,993 163,309 Net income available to common unitholders per unit – basic 0.36 0.27 0.34 1.58 Net income available to common unitholders per unit – diluted 0.36 0.27 0.33 1.57 ___________________ (1) The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. For the year ended December 31, 2018 , the summation of the quarterly net income available to common stockholders per share does not equal the annual number reported on the consolidated statements of operations due to the Company’s at-the-market stock offering programs that occurred during the year.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 15, 2020 , $53.2 million of dividends were paid out to common stockholders, common unitholders and RSU holders of record on December 31, 2019 . On January 31, 2020 , the Executive Compensation Committee granted 109,359 Time-Based RSUs and 154,267 Performance-Based RSUs to key employees under the 2006 Plan. The compensation cost related to the RSUs is expected to be recognized over a period of three years .

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS Years ended December 31, 2019 , 2018 and 2017 (in thousands) Balance at Beginning of Period (1) Charged to Costs and Expenses (2) Recoveries (Deductions) Balance at End of Period Allowance for Uncollectible Tenant Receivables for the year ended December 31, 2019 – Allowance for uncollectible tenant receivables $ 512 $ 907 $ (248 ) $ 1,171 2018 – Allowance for uncollectible tenant receivables 2,309 2,604 (274 ) 4,639 2017 – Allowance for uncollectible tenant receivables 1,712 1,517 (920 ) 2,309 Allowance for Deferred Rent Receivables for the year ended December 31, 2019 – Allowance for deferred rent $ 195 $ 1,357 $ — $ 1,552 2018 – Allowance for deferred rent 3,238 165 (64 ) 3,339 2017 – Allowance for deferred rent 1,524 1,752 (38 ) 3,238 __________________ (1) On January 1, 2019, the Company adopted Topic 842 on a modified retrospective basis and recognized a cumulative-effect adjustment to distributions in excess of earnings related to the allowances for uncollectible tenant receivables and deferred rent receivables. As such, the ending balances of the allowances for uncollectible tenant receivables and deferred rent receivables at December 31, 2018 do not equal the beginning balances on January 1, 2019. (2) For the year ended December 31, 2019, amounts do not reflect leases deemed not probable of collection for which we reversed the associated revenue under Topic 842. In addition, for the years ended December 31, 2019 and 2018 , $0.7 million and $2.9 million

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III - Real Estate and Accumulated Depreciation	SCHEDULE III – REAL ESTATE AND ACCUMULATED DEPRECIATION December 31, 2019 Initial Cost Gross Amounts at Which Carried at Close of Period Property Location Encumb- rances Land and improve- ments Buildings and Improve- ments Costs Capitalized Subsequent to Acquisition/ Improvement Land and improve- ments Buildings and Improve- ments Total Accumulated Depreciation Depreci- ation Life (1) Date of Acquisition (A)/ Construction (C) (2) Rentable Square Feet (3) (unaudited) ($ in thousands) Office Properties: 3077-3243 S. La Cienega Blvd., Culver City, CA $ 150,718 $ 31,032 $ 2 $ 150,718 $ 31,034 $ 181,752 $ 1,227 35 2019 A 151,908 2240 E. Imperial Highway, El Segundo, CA 1,044 11,763 29,542 1,048 41,301 42,349 26,943 35 1983 C 122,870 2250 E. Imperial Highway, El Segundo, CA 2,579 29,062 36,294 2,547 65,388 67,935 54,789 35 1983 C 298,728 2260 E. Imperial Highway, El Segundo, CA 2,518 28,370 36,764 2,547 65,105 67,652 16,320 35 1983 C 298,728 909 N. Pacific Coast Highway, El Segundo, CA 3,577 34,042 50,104 3,577 84,146 87,723 41,765 35 2005 C 244,136 999 N. Pacific Coast Highway, El Segundo, CA 1,407 34,326 16,897 1,407 51,223 52,630 25,350 35 2003 C 128,588 6115 W. Sunset Blvd., Los Angeles, CA (4) 1,313 3 16,436 2,455 15,297 17,752 2,165 35 2015 C 26,105 6121 W. Sunset Blvd., Los Angeles, CA (4) 11,120 4,256 43,971 8,703 50,644 59,347 7,262 35 2015 C 91,173 1525 N. Gower St., Los Angeles, CA (4) 1,318 3 9,641 1,318 9,644 10,962 1,206 35 2016 C 9,610 1575 N. Gower St., Los Angeles, CA (4) 22,153 51 119,460 22,153 119,511 141,664 11,813 35 2016 C 251,245 1500 N. El Centro Ave., Los Angeles, CA (4) 9,235 21 58,603 9,235 58,624 67,859 6,208 35 2016 C 104,504 1550 N. El Centro Ave., Los Angeles, CA (4) (5) 16,970 39 135,847 16,970 135,886 152,856 13,895 35 2016 C — 6255 W. Sunset Blvd., Los Angeles, CA 18,111 60,320 46,112 18,111 106,432 124,543 35,548 35 2012 A 323,920 3750 Kilroy Airport Way, Long Beach, CA — 1,941 11,610 — 13,551 13,551 10,822 35 1989 C 10,457 3760 Kilroy Airport Way, Long Beach, CA — 17,467 14,902 — 32,369 32,369 26,878 35 1989 C 165,278 3780 Kilroy Airport Way, Long Beach, CA — 22,319 26,442 — 48,761 48,761 39,320 35 1989 C 221,452 3800 Kilroy Airport Way, Long Beach, CA — 19,408 21,806 — 41,214 41,214 24,877 35 2000 C 192,476 3840 Kilroy Airport Way, Long Beach, CA — 13,586 10,666 — 24,252 24,252 16,162 35 1999 C 136,026 3880 Kilroy Airport Way, Long Beach, CA — 9,704 11,463 — 21,167 21,167 4,517 35 1997 A 96,035 3900 Kilroy Airport Way, Long Beach, CA — 12,615 12,433 — 25,048 25,048 18,248 35 1997 A 129,893 Kilroy Airport Center, Phase IV, Long Beach, CA (6) — — 4,997 — 4,997 4,997 4,997 35 — — 8560 W. Sunset Blvd., West Hollywood, CA 9,720 50,956 1,587 9,720 52,543 62,263 6,289 35 2016 A 71,875 8570 W Sunset Blvd., West Hollywood, CA 31,693 27,974 4,589 31,693 32,563 64,256 3,090 35 2016 A 43,603 8580 W. Sunset Blvd., West Hollywood, CA 10,013 3,695 648 10,013 4,343 14,356 392 35 2016 A 7,126 8590 W. Sunset Blvd., West Hollywood, CA 39,954 27,884 5,192 39,954 33,076 73,030 3,370 35 2016 A 56,095 12100 W. Olympic Blvd., Los Angeles, CA $ 170,000 (7) 352 45,611 18,617 9,633 54,947 64,580 29,197 35 2003 C 152,048 12200 W. Olympic Blvd., Los Angeles, CA (7) 4,329 35,488 24,224 3,977 60,064 64,041 39,654 35 2000 C 150,832 12233 W. Olympic Blvd., Los Angeles, CA 22,100 53,170 4,676 22,100 57,846 79,946 14,055 35 2012 A 151,029 12312 W. Olympic Blvd., Los Angeles, CA (7) 3,325 12,202 12,346 3,399 24,474 27,873 13,463 35 1997 A 76,644 1633 26th St., Santa Monica, CA 2,080 6,672 3,581 2,040 10,293 12,333 7,177 35 1997 A 43,857 2100/2110 Colorado Ave., Santa Monica, CA 5,474 26,087 14,678 5,476 40,763 46,239 25,730 35 1997 A 102,864 3130 Wilshire Blvd., Santa Monica, CA 8,921 6,579 16,799 9,188 23,111 32,299 15,989 35 1997 A 90,074 501 Santa Monica Blvd., Santa Monica, CA 4,547 12,044 15,889 4,551 27,929 32,480 17,346 35 1998 A 76,803 KILROY REALTY CORPORATION AND KILROY REALTY, L.P. SCHEDULE III – REAL ESTATE AND ACCUMULATED DEPRECIATION – (Continued) December 31, 2019 Initial Cost Gross Amounts at Which Carried at Close of Period Property Location Encumb- rances Land and improve- ments Buildings and Improve- ments Costs Capitalized Subsequent to Acquisition/ Improvement Land and improve- ments Buildings and Improve- ments Total Accumulated Depreciation Depreci- ation Life (1) Date of Acquisition (A)/ Construction (C) (2) Rentable Square Feet (3) (unaudited) ($ in thousands) 12225 El Camino Real, Del Mar, CA 1,700 9,633 3,714 1,673 13,374 15,047 9,224 35 1998 A 58,401 12235 El Camino Real, Del Mar, CA 1,507 8,543 9,022 1,540 17,532 19,072 10,435 35 1998 A 53,751 12340 El Camino Real, Del Mar, CA 4,201 13,896 11,660 4,201 25,556 29,757 12,128 35 2002 C 89,272 12390 El Camino Real, Del Mar, CA 3,453 11,981 8,804 3,453 20,785 24,238 9,540 35 2000 C 70,140 12348 High Bluff Dr., Del Mar, CA 1,629 3,096 6,323 1,629 9,419 11,048 6,636 35 1999 C 38,806 12400 High Bluff Dr., Del Mar, CA 15,167 40,497 14,473 15,167 54,970 70,137 28,866 35 2004 C 209,220 3579 Valley Centre Dr., Del Mar, CA 2,167 6,897 7,628 2,858 13,834 16,692 10,015 35 1999 C 54,960 3611 Valley Centre Dr., Del Mar, CA 4,184 19,352 19,881 5,259 38,158 43,417 25,713 35 2000 C 129,656 3661 Valley Centre Dr., Del Mar, CA 4,038 21,144 18,843 4,725 39,300 44,025 22,291 35 2001 C 128,364 3721 Valley Centre Dr., Del Mar, CA 4,297 18,967 14,705 4,254 33,715 37,969 17,509 35 2003 C 115,193 3811 Valley Centre Dr., Del Mar, CA 3,452 16,152 20,234 4,457 35,381 39,838 22,848 35 2000 C 112,067 12770 El Camino Real, Del Mar, CA 9,360 — 33,708 9,360 33,708 43,068 3,281 35 2015 C 73,032 12780 El Camino Real, Del Mar, CA 18,398 54,954 19,637 18,398 74,591 92,989 15,891 35 2013 A 140,591 12790 El Camino Real, Del Mar, CA 10,252 21,236 1,915 10,252 23,151 33,403 5,768 35 2013 A 78,836 3745 Paseo Place, Del Mar, CA (Retail) (8) 24,358 — 71,800 24,358 71,800 96,158 1,683 35 2019 C — 3200 Paseo Village Way, San Diego, CA (Resi Phase I) (9) 40,186 — 102,749 40,186 102,749 142,935 937 35 2019 C — 13280 Evening Creek Dr. South, I-15 Corridor, CA 3,701 8,398 4,729 3,701 13,127 16,828 5,809 35 2008 C 41,196 13290 Evening Creek Dr. South, I-15 Corridor, CA 5,229 11,871 6,128 5,229 17,999 23,228 6,797 35 2008 C 61,180 13480 Evening Creek Dr. South, I-15 Corridor, CA 7,997 — 52,826 7,997 52,826 60,823 20,167 35 2008 C 154,157 13500 Evening Creek Dr. South, I-15 Corridor, CA 7,581 35,903 18,106 7,581 54,009 61,590 22,402 35 2004 A 137,658 13520 Evening Creek Dr. South, I-15 Corridor, CA 7,580 35,903 17,778 7,580 53,681 61,261 24,885 35 2004 A 146,701 2305 Historic Decatur Rd., Point Loma, CA 5,240 22,220 7,309 5,240 29,529 34,769 10,801 35 2010 A 107,456 4690 Executive Dr., University Towne Centre, CA 1,623 7,926 3,722 1,623 11,648 13,271 7,829 35 1999 A 47,846 4100 Bohannon Dr., Menlo Park, CA (10) 4,835 15,526 567 4,860 16,068 20,928 4,557 35 2012 A 47,379 4200 Bohannon Dr., Menlo Park, CA (10) 4,798 15,406 3,703 4,662 19,245 23,907 5,788 35 2012 A 45,451 4300 Bohannon Dr., Menlo Park, CA (10) 6,527 20,958 3,248 6,470 24,263 30,733 7,803 35 2012 A 63,079 4400 Bohannon Dr., Menlo Park, CA (10) 4,798 15,406 2,905 4,939 18,170 23,109 5,779 35 2012 A 48,146 4500 Bohannon Dr., Menlo Park, CA (10) 6,527 20,957 3,422 6,470 24,436 30,906 6,552 35 2012 A 63,078 4600 Bohannon Dr., Menlo Park, CA (10) 4,798 15,406 3,571 4,939 18,836 23,775 5,660 35 2012 A 48,147 4700 Bohannon Dr., Menlo Park, CA (10) 6,527 20,958 1,488 6,470 22,503 28,973 6,326 35 2012 A 63,078 1290 - 1300 Terra Bella Ave., Mountain View, CA 28,730 27,555 61 28,730 27,616 56,346 4,809 35 2016 A 114,175 331 Fairchild Dr., Mountain View, CA 18,396 17,712 7,962 18,396 25,674 44,070 5,575 35 2013 C 87,147 680 E. Middlefield Rd., Mountain View, CA 34,605 — 56,470 34,605 56,470 91,075 9,813 35 2014 C 170,090 690 E. Middlefield Rd., Mountain View, CA 34,755 — 56,713 34,755 56,713 91,468 9,855 35 2014 C 170,823 1701 Page Mill Rd., Palo Alto, CA — 99,522 30 — 99,552 99,552 9,002 35 2016 A 128,688 KILROY REALTY CORPORATION AND KILROY REALTY, L.P. SCHEDULE III – REAL ESTATE AND ACCUMULATED DEPRECIATION – (Continued) December 31, 2019 Initial Cost Gross Amounts at Which Carried at Close of Period Property Location Encumb- rances Land and improve- ments Buildings and Improve- ments Costs Capitalized Subsequent to Acquisition/ Improvement Land and improve- ments Buildings and Improve- ments Total Accumulated Depreciation Depreci- ation Life (1) Date of Acquisition (A)/ Construction (C) (2) Rentable Square Feet (3) (unaudited) ($ in thousands) 3150 Porter Dr., Palo Alto, CA — 21,715 4 — 21,719 21,719 2,387 35 2016 A 36,897 900 Jefferson Ave., Redwood City, CA (11) 16,668 — 109,375 18,063 107,980 126,043 15,824 35 2015 C 228,505 900 Middlefield Rd., Redwood City, CA (11) 7,959 — 50,114 8,626 49,447 58,073 6,941 35 2015 C 118,764 303 Second St., San Francisco, CA (12) 63,550 154,153 84,572 63,550 238,725 302,275 83,973 35 2010 A 784,658 100 First St., San Francisco, CA (13) 49,150 131,238 64,883 49,150 196,121 245,271 62,989 35 2010 A 467,095 250 Brannan St., San Francisco, CA 7,630 22,770 9,932 7,630 32,702 40,332 10,651 35 2011 A 100,850 201 Third St., San Francisco, CA 19,260 84,018 66,962 19,260 150,980 170,240 55,837 35 2011 A 346,538 301 Brannan St., San Francisco, CA 5,910 22,450 8,174 5,910 30,624 36,534 10,091 35 2011 A 82,834 360 Third St., San Francisco, CA — 88,235 121,323 28,504 181,054 209,558 46,907 35 2011 A 429,796 333 Brannan St., San Francisco, CA 18,645 — 81,016 18,645 81,016 99,661 8,826 35 2016 C 185,602 350 Mission St., San Francisco, CA 52,815 — 213,450 52,815 213,450 266,265 24,500 35 2016 C 455,340 100 Hooper St., San Francisco, CA 78,564 — 196,251 88,510 186,305 274,815 5,978 35 2018 C 394,340 345 Brannan St., San Francisco, CA 29,405 113,179 1,322 29,403 114,503 143,906 3,697 35 2018 A 110,050 345 Oyster Point Blvd., South San Francisco, CA 13,745 18,575 1 13,745 18,576 32,321 1,167 35 2018 A 40,410 347 Oyster Point Blvd., South San Francisco, CA 14,071 18,289 44 14,071 18,333 32,404 1,150 35 2018 A 39,780 349 Oyster Point Blvd., South San Francisco, CA 23,112 22,601 324 23,112 22,925 46,037 1,926 35 2018 A 65,340 505 Mathilda Ave., Sunnyvale, CA 37,843 1,163 50,450 37,943 51,513 89,456 7,827 35 2014 C 212,322 555 Mathilda Ave., Sunnyvale, CA 37,843 1,163 50,447 37,943 51,510 89,453 7,827 35 2014 C 212,322 605 Mathilda Ave., Sunnyvale, CA 29,014 891 77,281 29,090 78,096 107,186 17,289 35 2014 C 162,785 599 Mathilda Ave., Sunnyvale, CA 13,538 12,559 139 13,538 12,698 26,236 4,147 35 2012 A 76,031 1800 Owens St., San Francisco, CA (14) 95,388 — 428,066 95,388 428,066 523,454 4,467 35 2019 C — 601 108th Ave., Bellevue, WA — 214,095 38,536 — 252,631 252,631 79,397 35 2011 A 488,470 10900 NE 4th St., Bellevue, WA 25,080 150,877 40,547 25,080 191,424 216,504 54,159 35 2012 A 428,557 837 N. 34th St., Lake Union, WA — 37,404 4,950 — 42,354 42,354 11,132 35 2012 A 112,487 701 N. 34th St., Lake Union, WA — 48,027 8,226 — 56,253 56,253 15,982 35 2012 A 141,860 801 N. 34 St., Lake Union, WA — 58,537 17,222 — 75,759 75,759 16,318 35 2012 A 169,412 320 Westlake Ave. North, WA 89,502 (15) 14,710 82,018 14,378 14,710 96,396 111,106 19,817 35 2013 A 184,644 321 Terry Avenue North, Lake Union, WA (15) 10,430 60,003 10,321 10,430 70,324 80,754 15,561 35 2013 A 135,755 401 Terry Avenue North, Lake Union, WA 22,500 77,046 13 22,500 77,059 99,559 15,556 35 2014 A 140,605 TOTAL OPERATING PROPERTIES 259,502 1,413,997 2,717,671 3,200,975 1,466,166 65 5,866,477 7,332,643 1,561,361 13,475,795 Undeveloped land and construction in progress — 1,058,176 — 1,237,954 1,058,176 1,237,954 2,296,130 — — TOTAL ALL PROPERTIES $ 259,502 (16) $ 2,472,173 $ 2,717,671 $ 4,438,929 $ 2,524,342 $ 7,104,432 $ 9,628,773 $ 1,561,361 13,475,795 KILROY REALTY CORPORATION AND KILROY REALTY, L.P. SCHEDULE III – REAL ESTATE AND ACCUMULATED DEPRECIATION – (Continued) December 31, 2019 __________________ (1) The initial costs of buildings and improvements are depreciated over 35 years using a straight-line method of accounting; improvements capitalized subsequent to acquisition are depreciated over the shorter of the lease term or useful life, generally ranging from one to 20 years . (2) Represents our date of construction or acquisition, or of our predecessor, the Kilroy Group. (3) Includes square footage from our stabilized portfolio. (4) These properties include the costs of a shared parking structure for a complex comprised of five office buildings and one residential tower. The costs of the parking structure are allocated amongst the six buildings. (5) This property represents the 200 -unit Columbia Square - Residential tower that stabilized in 2016. (6) These costs represent infrastructure costs incurred in 1989. During the third quarter of 2009, we exercised our option to terminate the ground lease at Kilroy Airport Center, Phase IV in Long Beach, California. We had previously leased this land, which is adjacent to our Office Properties at Kilroy Airport Center, Long Beach, for potential future development opportunities. (7) These properties secure a $170.0 million mortgage note. (8) This property is currently in the tenant improvement phase of our in-process development projects and not yet in the stabilized portfolio. The estimated rentable square feet for this property is 96,000 rentable square feet. (9) This property represents the first completed phase of the One Paseo residential property containing 237 units. (10) These properties secure intercompany promissory notes between KRLP and the consolidated property partnerships. (11) These properties are owned by Redwood City Partners LLC, a consolidated property partnership. (12) This property is owned by 303 Second Street Member LLC, a consolidated property partnership. (13) This property is owned by 100 First Street Member LLC, a consolidated property partnership. (14) This property is currently in the tenant improvement phase of our in-process development projects and not yet in the stabilized portfolio. The estimated rentable square feet for this property is 750,000 rentable square feet. (15) These properties secure a $89.5 million mortgage note. (16) Represents gross aggregate principal amount before the effect of the deferred financing costs of $0.9 million as of December 31, 2019 .units. As of December 31, 2019 , the aggregate gross cost of property included above for federal income tax purposes approximated $7.9 billion . This amount excludes approximately $0.2 billion of gross costs attributable to properties held in VIEs at December 31, 2019 to facilitate potential future Section 1031 Exchanges. The following table reconciles the historical cost of total real estate held for investment from January 1, 2017 to December 31, 2019 : Year Ended December 31, 2019 2018 (1) 2017 (in thousands) Total real estate held for investment, beginning of year $ 8,426,632 $ 7,417,777 $ 7,060,754 Additions during period: Acquisitions 460,512 581,671 19,829 Improvements, etc. 890,654 724,016 533,939 Total additions during period 1,351,166 1,305,687 553,768 Deductions during period: Cost of real estate sold (120,788 ) (286,623 ) (191,610 ) Other (28,237 ) (10,209 ) (5,135 ) Total deductions during period (149,025 ) (296,832 ) (196,745 ) Total real estate held for investment, end of year $ 9,628,773 $ 8,426,632 $ 7,417,777 __________________ (1) Amounts presented in Improvements, etc. and Other have been revised for the year ended December 31, 2018 to conform to the current year presentation with amounts transferred from undeveloped land and construction in progress to land and improvements and buildings and improvements presented on a net basis, which did not have any impact on total real estate held for investment at December 31, 2018 . The following table reconciles the accumulated depreciation from January 1, 2017 to December 31, 2019 : Year Ended December 31, 2019 2018 2017 (in thousands) Accumulated depreciation, beginning of year $ 1,391,368 $ 1,264,162 $ 1,139,853 Additions during period: Depreciation of real estate 211,893 198,578 190,515 Total additions during period 211,893 198,578 190,515 Deductions during period: Write-offs due to sale (41,655 ) (71,372 ) (66,206 ) Properties held for sale — — — Other (245 ) — — Total deductions during period (41,900 ) (71,372 ) (66,206 ) Accumulated depreciation, end of year $ 1,561,361 $ 1,391,368 $ 1,264,162

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Basis of Presentation and Significant Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements of the Company include the consolidated financial position and results of operations of the Company, the Operating Partnership, the Finance Partnership, 303 Second LLC, 100 First LLC, Redwood LLC and all of our wholly-owned and controlled subsidiaries. The consolidated financial statements of the Operating Partnership include the consolidated financial position and results of operations of the Operating Partnership, the Finance Partnership, 303 Second LLC, 100 First LLC, Redwood LLC and all of our wholly-owned and controlled subsidiaries. All intercompany balances and transactions have been eliminated in the consolidated financial statements.
Partially Owned Entities and Variable Interest Entities	Our accounting policy is to consolidate entities in which we have a controlling financial interest and significant decision making control over the entity's operations. In determining whether we have a controlling financial interest in a partially owned entity and the requirement to consolidate the accounts of that entity, we consider factors such as ownership interest, board representation, management representation, size of our investment (including loans), authority to control decisions, and contractual and substantive participating rights of the members. In addition to evaluating control rights, we consolidate entities in which the other members have no substantive kick-out rights to remove the Company as the managing member. Entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or the holders of the equity investment at risk do not have a controlling financial interest are VIEs. We evaluate whether an entity is a VIE and whether we are the primary beneficiary. We are deemed to be the primary beneficiary of a VIE when we have the power to direct the activities of the VIE that most significantly impact the VIEs’ economic performance and the obligation to absorb losses or receive benefits that could potentially be significant to the VIE.
Accounting Pronouncement Adopted and Accounting Standards Issued But Not Yet Effective	Accounting Pronouncements Adopted January 1, 2019 Effective January 1, 2019, we adopted Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2016-02 “Leases (Topic 842)” (“Topic 842”) and the related FASB ASU Nos. 2018-01, 2018-10, 2018-11, 2018-20 and 2019-01 which provide practical expedients, technical corrections and improvements for certain aspects of ASU 2016-02, on a modified retrospective basis. Topic 842 establishes a single comprehensive model for entities to use in accounting for leases and supersedes the existing leasing guidance. We evaluated each of the Company’s contracts to determine if the contract is or contains a lease and concluded that Topic 842 is applicable to the Company as a lessor in its tenant lease agreements and as a lessee in its ground leases. Lessor Accounting As a lessor, the Company’s leases with tenants for its real estate assets generally provide for the lease of space, as well as common area maintenance and parking. Under Topic 842, the lease of space is considered a lease component while the common area maintenance billings and tenant parking are considered nonlease components, which fall under revenue recognition guidance in FASB Accounting Standards Codification Topic 606 “Revenue from Contracts with Customers” (“Topic 606”). However, upon adopting the guidance in Topic 842, the Company determined that its tenant leases met the criteria to apply the practical expedient provided by ASU 2018-11 to recognize the lease and non-lease components together as one single component. This conclusion was based on the consideration that 1) the timing and pattern of transfer of the nonlease components and associated lease component are the same, and 2) the lease component, if accounted for separately, would be classified as an operating lease. As the lease of space is the predominant component of the Company’s leasing arrangements, we accounted for all lease and non-lease components as one single component under Topic 842. As a result, the adoption of Topic 842 did not have any impact on the Company’s timing or pattern of recognition of rental revenues as compared to previous guidance. Transient daily parking revenue is accounted for under the guidance in Topic 606 and included in other property income in our consolidated statements of operations. To reflect their recognition as one lease component, base rental revenues, additional rental revenues (which consist of amounts due from tenants for common area maintenance, real estate taxes, and other recoverable costs) and other lease related property income related to leases that also meet the requirements of the practical expedient provided by ASU 2018-11 have been combined in one line item subsequent to the adoption of Topic 842 for the year ended December 31, 2019 in rental income on the Company’s consolidated statements of operations. In addition, under Topic 842, lessor costs for certain services directly reimbursed by tenants, which were previously presented on a net basis under previous guidance, are required to be presented on a gross basis in revenues and expenses. During the year ended December 31, 2019 , we incurred additional property expenses of $13.9 million for which we were reimbursed, that were not required to be grossed up under the previous guidance. We presented this amount on a gross basis within rental income and property expenses in the Company’s consolidated statements of operations as a result of the adoption, which had no impact on net income. Accounting Standards Issued But Not Yet Effective at December 31, 2019 Accounting Pronouncements Adopted January 1, 2020 ASU No. 2016-13 “Financial Instruments - Credit Losses (Topic 326)” On June 16, 2016, the FASB issued ASU No. 2016-13 (“ASU 2016-13”) to amend the accounting for credit losses for certain financial instruments. Under the new guidance, an entity recognizes its estimate of expected credit losses as an allowance, which the FASB believes will result in more timely recognition of such losses. In November 2018, the FASB released ASU No. 2018-19 “ Codification Improvements to Topic 326, Financial Instruments - Credit Losses. ” This ASU clarifies that receivables arising from operating leases are not within the scope of Subtopic 326-20 “Financial Instruments – Credit Losses.” Instead, impairment of receivables arising from operating leases should be accounted for under Subtopic 842-30 “Leases – Lessor.” ASU 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The adoption did not have a material impact on the consolidated financial statements or notes to the consolidated financial statements. ASU No. 2018-13 “Fair Value Measurement (Topic 820)” On August 28, 2018, the FASB issued ASU No. 2018-13 (“ASU 2018-13”) to amend the disclosure requirements for fair value measurements. The amendments in ASU 2018-13 include new, modified and eliminated disclosure requirements and are the result of a broader disclosure project called FASB Concepts Statement, Conceptual Framework for Financial Reporting - Chapter 8: Notes to Financial Statements , which the Board finalized on August 28, 2018. The Board used the guidance in the Concepts Statement to improve the effectiveness of ASC 820’s disclosure requirements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for any eliminated or modified disclosures. The adoption did not have a material impact on the disclosures in the notes to the consolidated financial statements. ASU No. 2018-15 “Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40)” On August 29, 2018, the FASB issued ASU No. 2018-15 (“ASU 2018-15”) to amend a customer’s accounting for implementation costs incurred in a cloud computing arrangement that is a service contract. ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). ASU 2018-15 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period. ASU 2018-15 can be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. The adoption did not have a material impact on the consolidated financial statements or notes to the consolidated financial statements. Upon the adoption of Topic 842 on January 1, 2019, the method for recognizing revenue includes a binary assessment of whether or not substantially all of the amounts due under a tenant’s lease agreement are probable of collection. For leases that are deemed probable of collection, revenue is recorded on a straight-line basis over the lease term. For leases that are deemed not probable of collection, revenue is recorded as the lesser of (i) the amount which would be recognized on a straight-line basis or (ii) cash that has been received from the tenant, with any tenant and deferred rent receivable balances charged as a direct write-off against rental income in the period of the change in the collectability determination. Refer to our Significant Accounting Policies below for further discussion of our revenue recognition and allowance for uncollectible tenant and deferred rent receivables policies.
Revenue Recognition, Base Rent, Additional Rent - Reimbursements from Tenants, Other Property Income, Uncollectible Lease Receivables and Allowance for Tenant and Deferred Rent Receivables	Revenue Recognition Rental revenue for office and retail operating properties is our principal source of revenue. We recognize revenue from base rent, additional rent (which consists of amounts due from tenants for common area maintenance, real estate taxes, and other recoverable costs), parking and other lease-related revenue once all of the following criteria are met: (i) the agreement has been fully executed and delivered, (ii) services have been rendered, (iii) the amount is fixed or determinable and (iv) payment has been received or the collectability of the amount due is probable. Lease termination fees are amortized over the remaining lease term, if applicable. If there is no remaining lease term, they are recognized when received and realized. Minimum annual rental revenues are recognized in rental revenues on a straight-line basis over the non-cancellable term of the related lease. Base Rent The timing of when we commence rental revenue recognition for office and retail properties depends largely on our conclusion as to whether the Company or the tenant is the owner for accounting purposes of tenant improvements at the leased property. When we conclude that we are the owner of tenant improvements for accounting purposes, we record the cost to construct the tenant improvements as an asset and commence rental revenue recognition when the tenant takes possession of or controls the finished space, which is generally when tenant improvements being recorded as our assets are substantially complete. In certain instances, when we conclude that the tenant is the owner of certain tenant improvements for accounting purposes, rental revenue recognition begins when the tenant takes possession or controls the physical use of the leased space, which may occur in phases or for an entire building or project. The determination of who owns the tenant improvements is made on a lease-by-lease basis and has a significant effect on the timing of commencement of revenue recognition. When we conclude that the Company is the owner of tenant improvements for accounting purposes, we record the cost to construct the tenant improvements, including costs paid for or reimbursed by the tenants, as a capital asset. For these tenant-funded tenant improvements, we record the amount funded by or reimbursed by tenants as deferred revenue, which is amortized and recognized as rental income on a straight-line basis over the term of the related lease. When we conclude that the tenant is the owner of certain tenant improvements for accounting purposes, we record our contribution towards those tenant-owned improvements as a lease incentive, which is included in deferred leasing costs and acquisition-related intangible assets, net on our consolidated balance sheets and amortized as a reduction to rental revenue on a straight-line basis over the term of the related lease. For residential properties, we commence revenue recognition upon lease commencement. Residential rental revenue is recognized on a straight-line basis over the term of the related lease, net of any concessions. Additional Rent - Reimbursements from Tenants Additional rent, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized in rental income in the period the recoverable costs are incurred. Prior to the adoption of Topic 842, such amounts were recognized in revenue as tenant reimbursements. Additional rent where we pay the associated costs directly to third-party vendors and are reimbursed by our tenants are recognized and recorded on a gross basis, with the corresponding expense recognized in property expenses or real estate taxes. Prior to the adoption of Topic 842, recoverable costs were generally recognized and recorded on a gross basis when we were the primary obligor with respect to purchasing goods and services from third-party suppliers, had discretion in selecting the supplier, and had credit risk. Other Property Income Other property income primarily includes amounts recorded in connection with transient daily parking, tenant bankruptcy settlement payments, broken deal income and property damage settlement related payments. Other property income also includes miscellaneous income from tenants, restoration fees and fees for late rental payments. Amounts recorded within other property income fall within the scope of Topic 606 and are recognized as revenue at the point in time when control of the goods or services transfers to the customer and our performance obligation is satisfied. Uncollectible Lease Receivables and Allowances for Tenant and Deferred Rent Receivables We carry our current and deferred rent receivables net of allowances for amounts that may not be collected. Prior to the adoption of Topic 842 on January 1, 2019, the allowances were increased or decreased through provision for bad debts on our consolidated statements of operations. Upon the adoption of Topic 842 on January 1, 2019, the allowances are increased or decreased through rental income, and our determination of the adequacy of the Company’s allowances for tenant receivables includes a binary assessment of whether or not substantially all of the amounts due under a tenant’s lease agreement are probable of collection. Such assessment involves using a methodology that incorporates a specific identification analysis and an aging analysis and considers the current economic and business environment. This determination requires significant judgment and estimates about matters that are uncertain at the time the estimates are made, including the creditworthiness of specific tenants, specific industry trends and conditions, and general economic trends and conditions. For leases that are deemed probable of collection, revenue continues to be recorded on a straight-line basis over the lease term. For leases that are deemed not probable of collection, revenue is recorded as the lesser of (i) the amount which would be recognized on a straight-line basis or (ii) cash that has been received from the tenant, with any tenant and deferred rent receivable balances charged as a direct write-off against rental income in the period of the change in the collectability determination. For tenant and deferred rent receivables associated with leases whose rents are deemed probable of collection under Topic 842, we may record an allowance under other authoritative GAAP using a methodology that incorporates a specific identification analysis and an aging analysis and considers the current economic and business environment. This determination requires significant judgment and estimates about matters that are uncertain at the time the estimates are made, including the creditworthiness of specific tenants, specific industry trends and conditions, and general economic trends and conditions. Tenant and deferred rent receivables deemed probable of collection are carried net of allowances for uncollectible accounts, with increases or decreases in the allowances recorded through rental income on our consolidated statements of operations. Prior to the adoption of Topic 842 on January 1, 2019, the allowances were increased or decreased through provision for bad debts on our consolidated statements of operations. Current tenant receivables consist primarily of amounts due for contractual lease payments and reimbursements of common area maintenance expenses, property taxes, and other costs recoverable from tenants. With respect to the allowance for uncollectible tenant receivables, the specific identification methodology analysis relies on factors such as the age and nature of the receivables, the payment history and financial condition of the tenant, our assessment of the tenant’s ability to meet its lease obligations, and the status of negotiations of any disputes with the tenant. Deferred rent receivables represent the amount by which the cumulative straight-line rental revenue recorded to date exceeds cash rents billed to date under the lease agreement. With respect to the allowance for deferred rent receivables, given the longer-term nature of these receivables, the specific identification methodology analysis evaluates each of our significant tenants and any tenants on our internal watchlist and relies on factors such as each tenant’s financial condition and its ability to meet its lease obligations. We evaluate our reserve levels quarterly based on changes in the financial condition of tenants and our assessment of the tenant’s ability to meet its lease obligations, overall economic conditions, and the current business environment.
Acquisitions	Acquisitions Acquisitions of operating properties and development and redevelopment opportunities generally do not meet the definition of a business and are accounted for as asset acquisitions, as substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. For these asset acquisitions, we record the acquired tangible and intangible assets and assumed liabilities based on each asset’s and liability’s relative fair value at the acquisition date of the total purchase price plus any capitalized acquisition costs. We record the acquired tangible and intangible assets and assumed liabilities of acquisitions of operating properties and development and redevelopment opportunities that meet the accounting criteria to be accounted for as business combinations at fair value at the acquisition date. Transaction costs associated with asset acquisitions are capitalized as part of the purchase price of the acquisition. The acquired assets and assumed liabilities for an acquisition generally include but are not limited to (i) land and improvements, buildings and improvements, undeveloped land and construction in progress and (ii) identified tangible and intangible assets and liabilities associated with in-place leases, including tenant improvements, leasing costs, value of above-market and below-market operating leases and ground leases, acquired in-place lease values and tenant relationships, if any. Any debt assumed and equity (including common units of the Operating Partnership) issued in connection with a property acquisition is recorded at fair value on the date of acquisition. The fair value of land and improvements is derived from comparable sales of land and improvements within the same submarket and/or region. The fair value of buildings and improvements, tenant improvements and leasing costs considers the value of the property as if it was vacant as well as current replacement costs and other relevant market rate information. The fair value of the above-market or below-market component of an acquired in-place operating lease is based upon the present value (calculated using a market discount rate) of the difference between (i) the contractual rents to be paid pursuant to the lease over its remaining non-cancellable lease term and (ii) our estimate of the rents that would be paid using fair market rental rates and rent escalations at the date of acquisition measured over the remaining non-cancellable term of the lease for above-market operating leases and the initial non-cancellable term plus the term of any below-market fixed rate renewal options, if applicable, for below-market operating leases. Our below-market operating leases generally do not include fixed rate or below-market renewal options. The amounts recorded for above-market operating leases are included in deferred leasing costs and acquisition-related intangible assets, net on the balance sheet and are amortized on a straight-line basis as a reduction of rental income over the remaining term of the applicable leases. The amounts recorded for below-market operating leases are included in deferred revenue and acquisition-related intangible liabilities, net on the balance sheet and are amortized on a straight-line basis as an increase to rental income over the remaining term of the applicable leases plus the term of any below-market fixed rate renewal options, if applicable. The amortization of a below-market ground lease obligation is recorded as an increase to ground lease expense in the consolidated statements of operations for the periods presented. The amortization of an above-market ground lease obligation is recorded as a decrease to ground lease expense in the consolidated statements of operations for the periods presented. The fair value of acquired in-place leases is derived based on our assessment of lost revenue and costs incurred for the period required to lease the “assumed vacant” property to the occupancy level when purchased. The amount recorded for acquired in-place leases is included in deferred leasing costs and acquisition-related intangible assets, net on the balance sheet and amortized as an increase to depreciation and amortization expense over the remaining term of the applicable leases. Fully amortized intangible assets are written off each quarter.
Operating Properties and Cost Capitalization and Depreciation and Amortization of Buildings and Improvements	Operating Properties Operating properties are generally carried at historical cost less accumulated depreciation. Properties held for sale are reported at the lower of the carrying value or the fair value less estimated cost to sell. The cost of operating properties includes the purchase price or development costs of the properties. Costs incurred for the renovation and betterment of the operating properties are capitalized to our investment in that property. Maintenance and repairs are charged to expense as incurred. When evaluating properties to be held and used for potential impairment, we first evaluate whether there are any indicators of impairment for any of our properties. If any impairment indicators are present for a specific property, we then evaluate the regional market conditions that could reasonably affect the property. If there are negative changes and trends in that regional market, we then perform an undiscounted cash flow analysis and compare the net carrying amount of the property to the property’s estimated undiscounted future cash flow over the anticipated holding period. If the estimated undiscounted future cash flow is less than the net carrying amount of the property, we perform an impairment loss calculation to determine if the fair value of the property is less than the net carrying value of the property. Our impairment loss calculation compares the net carrying amount of the property to the property’s estimated fair value, which may be based on estimated discounted future cash flow calculations or third-party valuations or appraisals. We would recognize an impairment loss if the property's net carrying amount exceeds the property's estimated fair value. If we were to recognize an impairment loss, the estimated fair value of the property becomes its new cost basis. For a depreciable long-lived asset, the new cost basis would be depreciated (amortized) over the remaining useful life of that asset. Cost Capitalization All costs clearly associated with the development, redevelopment and construction of a property are capitalized as project costs, including internal compensation costs. In addition, the following costs are capitalized as project costs during periods in which activities necessary to prepare development and redevelopment properties for their intended use are in progress: pre-construction costs essential to the development of the property, interest, real estate taxes and insurance. • For office and retail development and redevelopment properties that are pre-leased, we cease capitalization when revenue recognition commences, which is upon substantial completion of tenant improvements deemed to be the Company’s asset for accounting purposes. • For office and retail development and redevelopment properties that are not pre-leased, we may not immediately build out the tenant improvements. Therefore, we cease capitalization when revenue recognition commences upon substantial completion of the tenant improvements deemed to be the Company's asset for accounting purposes, but in any event, no later than one year after the cessation of major construction activities. We also cease capitalization on a development or redevelopment property when activities necessary to prepare the property for its intended use have been suspended. • For office and retail development or redevelopment properties with multiple tenants and staged leasing, we cease capitalization and begin depreciation on the portion of the development or redevelopment property for which revenue recognition has commenced. • For residential development properties, we cease capitalization when the property is substantially complete and available for occupancy. Once major base building construction activities have ceased and the development or redevelopment property or phases of the development or redevelopment project is placed in service, which may occur in phases or for an entire building or project, the costs capitalized to construction in progress are transferred to land and improvements, buildings and improvements, and deferred leasing costs on our consolidated balance sheets as the historical cost of the property. Depreciation and Amortization of Buildings and Improvements
Real Estate Assets Held for Sale, Dispositions and Discontinued Operations	Real Estate Assets Held for Sale, Dispositions and Discontinued Operations A real estate asset is classified as held for sale when certain criteria are met, including but not limited to the availability of the asset for immediate sale, the existence of an active program to locate a buyer and the probable sale or transfer of the asset within one year. If such criteria are met, we present the applicable assets and liabilities related to the real estate asset, if material, separately on the balance sheet as held for sale and we would cease to record depreciation and amortization expense. Real estate assets held for sale are reported at the lower of their carrying value or their estimated fair value less the estimated costs to sell. As of December 31, 2019 and 2018 , we did not have any properties classified as held for sale. Property disposals representing a strategic shift that have (or will have) a major effect on the Company’s operations and financial results, such as a major line of business, a major geographical area or a major equity investment, are required to be presented as discontinued operations. If we were to determine that a property disposition represents a strategic shift, the revenues, expenses and net gain (loss) on dispositions of the property would be recorded in discontinued operations for all periods presented through the date of the applicable disposition. The operations of the properties sold during the years ended December 31, 2019 , 2018 and 2017 are presented in continuing operations as they did not represent a strategic shift in the Company’s operations and financial results.
Cash and Cash Equivalents	Cash and Cash Equivalents
Restricted Cash	Restricted Cash Restricted cash consists of cash proceeds from dispositions that are temporarily held at qualified intermediaries for purposes of facilitating potential Section 1031 Exchanges and cash held in escrow related to acquisition and
Marketable Securities	Marketable securities reported in our consolidated balance sheets represent the assets held in connection with the Kilroy Realty Corporation 2007 Deferred Compensation Plan (the “Deferred Compensation Plan”) (see Note 16 “Employee Benefit Plans” for additional information). The Deferred Compensation Plan assets are held in a limited rabbi trust and invested in various mutual and money market funds. As a result, the marketable securities are treated as trading securities for financial reporting purposes and are adjusted to fair value at the end of each accounting period, with the corresponding gains and losses recorded in interest income and other net investment gains (losses).
Deferred Compensation Plan	At the time eligible management employees (“Participants”) defer compensation or earn mandatory Company contributions, or if we were to make a discretionary contribution, we record compensation cost and a corresponding deferred compensation plan liability, which is included in accounts payable, accrued expenses, and other liabilities on our consolidated balance sheets. This liability is adjusted to fair value at the end of each accounting period based on the performance of the benchmark funds selected by each Participant, and the impact of adjusting the liability to fair value is recorded as an increase or decrease to compensation cost. The impact of adjusting the deferred compensation plan liability to fair value and the changes in the value of the marketable securities held in connection with the Deferred Compensation Plan generally offset and therefore do not significantly impact net income.
Deferred Leasing Costs	Deferred Leasing Costs Costs incurred in connection with successful property leasing are capitalized as deferred leasing costs and classified as investing activities in the statement of cash flows. Under Topic 842, initial direct costs include only those costs that are incremental to the arrangement and would not have been incurred if the lease had not been obtained. As a result, subsequent to the adoption of Topic 842 on January 1, 2019, deferred leasing costs consist of leasing commissions paid to external third party brokers and lease incentives, and the Company no longer capitalizes internal leasing costs and third-party legal leasing costs. Prior to the adoption of Topic 842, deferred leasing costs consisted primarily of leasing commissions, lease incentives, legal costs and certain internal payroll costs. Deferred leasing costs are amortized using the straight-line method of accounting over the lives of the leases which generally range from one to 20 years . We reevaluate the remaining useful lives of leasing costs as the creditworthiness of our tenants and economic and market conditions change. If we determine that the estimated remaining life of a lease has changed, we adjust the amortization period accordingly. Fully amortized deferred leasing costs are written off each quarter.
Deferred Financing Costs, and Debt Discounts and Premiums	Deferred Financing Costs Financing costs related to the origination or assumption of long-term debt are deferred and generally amortized using the straight-line method of accounting, which approximates the effective interest method, over the contractual terms of the applicable financings. Fully amortized deferred financing costs are written off when the corresponding financing is repaid. Debt Discounts and Premiums Original issuance debt discounts and discounts/premiums related to recording debt acquired in connection with operating property acquisitions at fair value are generally amortized and accreted on a straight-line basis, which approximates the effective interest method. Discounts are recorded as additional interest expense from date of issuance or acquisition through the contractual maturity date of the related debt. Premiums are recorded as a reduction to interest expense from the date of issuance or acquisition through the contractual maturity date of the related debt.
Noncontrolling Interests and Common Partnership Interests	Noncontrolling Interests - Common Units of the Operating Partnership in the Company's Consolidated Financial Statements Common units of the Operating Partnership within noncontrolling interests in the Company’s consolidated financial statements represent the common limited partnership interests in the Operating Partnership not held by the Company (“noncontrolling common units”). Noncontrolling common units are presented in the equity section of the Company’s consolidated balance sheets and are reported at their proportionate share of the net assets of the Operating Partnership. Noncontrolling interests with redemption provisions that permit the issuer to settle in either cash or shares of common stock must be further evaluated to determine whether equity or temporary equity classification on the balance sheet is appropriate. Since the common units contain such a provision, we evaluated the accounting guidance and determined that the common units qualify for equity presentation in the Company’s consolidated financial statements. Net income attributable to noncontrolling common units is allocated based on their relative ownership percentage of the Operating Partnership during the reported period. The noncontrolling interest ownership percentage is determined by dividing the number of noncontrolling common units by the total number of common units outstanding. The issuance or redemption of additional shares of common stock or common units results in changes to the noncontrolling interest percentage as well as the total net assets of the Company. As a result, all equity transactions result in an allocation between equity and the noncontrolling interest in the Company’s consolidated balance sheets and statements of equity to account for the changes in the noncontrolling interest ownership percentage as well as the change in total net assets of the Company. Noncontrolling Interests in Consolidated Property Partnerships Noncontrolling interests in consolidated property partnerships represent the equity interests held by unrelated third parties in our three consolidated property partnerships (see Note 11 “Noncontrolling Interests on the Company’s Consolidated Financial Statements” and see Note 12 “Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements”). Noncontrolling interests in consolidated property partnerships are not redeemable and are presented as permanent equity in the Company's consolidated balance sheets. We account for the noncontrolling interests in consolidated property partnerships using the hypothetical liquidation at book value (“HLBV”) method to attribute the earnings or losses of the consolidated property partnerships between the controlling and noncontrolling interests. Under the HLBV method, the amounts reported as noncontrolling interests in consolidated property partnerships in the consolidated balance sheets represent the amounts the noncontrolling interests would hypothetically receive at each balance sheet reporting date under the liquidation provisions of the governing agreements assuming the net assets of the consolidated property partnerships were liquidated at recorded amounts and distributed between the controlling and noncontrolling interests in accordance with the governing documents. The net income attributable to noncontrolling interests in consolidated property partnerships in the consolidated statements of operations is associated with the increase or decrease in the noncontrolling interest holders’ contractual claims on the respective entities’ balance sheets assuming a hypothetical liquidation at the end of that reporting period when compared with their claims on the respective entities’ balance sheets assuming a hypothetical liquidation at the beginning of that reporting period, after removing any contributions or distributions. Common Partnership Interests on the Operating Partnership’s Consolidated Balance Sheets The common units held by the Company and the noncontrolling common units held by the common limited partners are both presented in the permanent equity section of the Operating Partnership’s consolidated balance sheets in partners’ capital. The redemption rights of the noncontrolling common units permit us to settle the redemption obligation in either cash or shares of the Company’s common stock at our option (see Note 11 “Noncontrolling Interests on the Company’s Consolidated Financial Statements” for additional information). Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements Noncontrolling interests in the Operating Partnership’s consolidated financial statements include the noncontrolling interest in property partnerships (see Note 12 “Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements”) and the Company’s 1.0% general partnership interest in the Finance Partnership. The 1.0% general partnership interest in the Finance Partnership noncontrolling interest is presented in the permanent equity section of the Operating Partnership’s consolidated balance sheets given that these interests are not convertible or redeemable into any other ownership interest of the Company or the Operating Partnership.
Equity Offerings	Equity Offerings Underwriting commissions and offering costs incurred in connection with common equity offerings and our at-the-market stock offering program (see Note 13 “Stockholders’ Equity of the Company”) are reflected as a reduction of additional paid-in capital. Issuance costs incurred in connection with preferred equity offerings are reflected as a reduction of the carrying value of the preferred equity. Sales of our common stock under forward equity sale agreements (such as those under the forward equity offering executed in August 2018 and those under the 2018 At-The-Market Program, as discussed in Note 13 “Stockholders’ Equity of the Company”) meet the derivatives and hedging guidance scope exception to be accounted for as equity instruments based on the following assessment: (i) none of the agreements’ exercise contingencies were based on observable markets or indices besides those related to the market for our own stock price and operations; and (ii) none of the settlement provisions precluded the agreements from being indexed to our own stock.
Share-based Incentive Compensation Accounting	Share-based Incentive Compensation Accounting Compensation cost for all share-based awards, including options, requires measurement at estimated fair value on the grant date. Compensation cost is recognized on a straight-line basis over the service vesting period, which represents the requisite service period. The grant date fair value of market measure-based share-based compensation plans are calculated using a Monte Carlo simulation pricing model. The grant date fair value of stock option grants is calculated using the Black-Scholes valuation model. Equity awards settled in cash are valued at the fair value of our common stock on the period end date through the settlement date. Equity awards settled in cash are remeasured at each reporting period and are recognized as a liability in the consolidated balance sheet during the vesting period until settlement. Forfeitures of all share-based awards are recognized when they occur. For share-based awards in which the performance period precedes the grant date, we recognize compensation cost over the requisite service period, which includes both the performance and service vesting periods, using the accelerated attribution expense method. The requisite service period begins on the date the Executive Compensation Committee authorizes the award and adopts any relevant performance measures. For share-based awards with performance-based measures, the total estimated compensation cost is based on our most recent estimate of the probable achievement of the pre-established specific corporate performance measures. These estimates are based on actual results and our latest internal forecasts for each performance measure. For share-based awards with market measures, the total estimated compensation cost is based on the fair value of the award at the grant date. For share-based awards with performance-based measures and market measures, the total estimated compensation cost is based on the fair value per share at the grant date multiplied by our most recent estimate of the number of shares to be earned based on actual results and the probable achievement of the pre-established corporate performance measures based on our latest internal forecasts. In accordance with the provisions of our share-based incentive compensation plan, we accept the return of shares of Company common stock, at the current quoted market price, from employees to satisfy minimum statutory tax-withholding requirements related to shares that vested during the period.
Basic and Diluted Net Income Available to Common Stockholders per Share	Basic and Diluted Net Income Available to Common Stockholders per Share Basic net income available to common stockholders per share is computed by dividing net income available to common stockholders, after preferred distributions and the allocation of income to participating securities, by the weighted-average number of shares of common stock outstanding for the period. Diluted net income available to common stockholders per share is computed by dividing net income available for common stockholders, after preferred distributions and the allocation of income to participating securities, by the sum of the weighted-average number of shares of common stock outstanding for the period plus the assumed exercise of all dilutive securities. The impact of the outstanding common units is considered in the calculation of diluted net income available to common stockholders per share. The common units are not reflected in the diluted net income available to common stockholders per share calculation because the exchange of common units into common stock is on a one for one basis, and the common units are allocated net income on a per share basis equal to the common stock (see Note 21 “Net Income Available to Common Stockholders Per Share of the Company”). Accordingly, any exchange would not have any effect on diluted net income (loss) available to common stockholders per share. Nonvested share-based payment awards (including nonvested restricted stock units (“RSUs”), vested market-measure RSUs and vested dividend equivalents issued to holders of RSUs) containing nonforfeitable rights to dividends or dividend equivalents are accounted for as participating securities and included in the computation of basic and diluted net income available to common stockholders per share pursuant to the two-class method. The dilutive effect of shares issuable under executed forward equity sale agreements and stock options are reflected in the weighted average diluted outstanding shares calculation by application of the treasury stock method. The dilutive effect of the outstanding nonvested shares of common stock (“nonvested shares”) and RSUs that have not yet been granted but are contingently issuable under the share-based compensation programs is reflected in the weighted average diluted shares calculation by application of the treasury stock method at the beginning of the quarterly period in which all necessary conditions have been satisfied. Basic and Diluted Net Income Available to Common Unitholders per Unit Basic net income available to common unitholders per unit is computed by dividing net income available to common unitholders, after preferred distributions and the allocation of income to participating securities, by the weighted-average number of vested common units outstanding for the period. Diluted net income available to common unitholders per unit is computed by dividing net income available to common unitholders, after preferred distributions and the allocation of income to participating securities, by the sum of the weighted-average number of common units outstanding for the period plus the assumed exercise of all dilutive securities. The dilutive effect of stock options, outstanding nonvested shares, RSUs, awards containing nonforfeitable rights to dividend equivalents and shares issuable under executed forward equity sale agreements are reflected in diluted net income available to common unitholders per unit in the same manner as noted above for net income available to common stockholders per share.
Fair Value Measurements	Fair Value Measurements The fair values of our financial assets and liabilities are disclosed in Note 19, “Fair Value Measurements and Disclosures,” to our consolidated financial statements. The only financial assets recorded at fair value on a recurring basis in our consolidated financial statements are our marketable securities. We elected not to apply the fair value option for any of our eligible financial instruments or other items. We determine the estimated fair value of financial assets and liabilities utilizing a hierarchy of valuation techniques based on whether the inputs to a fair value measurement are considered to be observable or unobservable in a marketplace. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our market assumptions. This hierarchy requires the use of observable market data when available. The following is the fair value hierarchy: • Level 1 – quoted prices for identical instruments in active markets; • Level 2 – quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active and model-derived valuations in which significant inputs and significant value drivers are observable in active markets; and • Level 3 – fair value measurements derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. We determine the fair value for the marketable securities using quoted prices in active markets for identical assets. Our other financial instruments, which are only disclosed at fair value, are comprised of secured debt, unsecured senior notes, unsecured line of credit and unsecured term loan facility. We generally determine the fair value of our secured debt, unsecured debt, and unsecured line of credit by performing discounted cash flow analyses using an appropriate market discount rate. We calculate the market rate by obtaining period-end treasury rates for maturities that correspond to the maturities of our fixed-rate debt and then adding an appropriate credit spread based on information obtained from third-party financial institutions. These credit spreads take into account factors, including but not limited to, our credit profile, the tenure of the debt, amortization period, whether the debt is secured or unsecured, and the loan-to-value ratio of the debt to the collateral. These calculations are significantly affected by the assumptions used, including the discount rate, credit spreads and estimates of future cash flow. We calculate the market rate of our unsecured line of credit, unsecured term loan facility, and unsecured term loan by obtaining the period-end London Interbank Offered Rate (“LIBOR”) and then adding an appropriate credit spread based on our credit ratings, and the amended terms of our unsecured line of credit, unsecured term loan facility, and unsecured term loan agreement. We determine the fair value of each of our publicly traded unsecured senior notes based on their quoted trading price at the end of the reporting period, if such prices are available. Carrying amounts of our cash and cash equivalents, restricted cash and accounts payable approximate fair value due to their short-term maturities.
Income Taxes	Income Taxes We have elected to be taxed as a REIT under Sections 856 through 860 of the Code. To qualify as a REIT, we must distribute annually at least 90% of our adjusted taxable income, as defined in the Code, to our stockholders and satisfy certain other organizational and operating requirements. We generally will not be subject to federal income taxes if we distribute 100% of our taxable income for each year to our stockholders. If we fail to qualify as a REIT in any taxable year, we will be subject to federal income taxes (including any applicable alternative minimum tax) on our taxable income at regular corporate rates and we may not be able to qualify as a REIT for four subsequent taxable years. Even if we qualify for taxation as a REIT, we may be subject to certain state and local taxes on our income and property and to federal income taxes and excise taxes on our undistributed taxable income. We believe that we have met all of the REIT distribution and technical requirements for the years ended December 31, 2019 , 2018 and 2017 , and we were not subject to any federal income taxes (see Note 25 “Tax Treatment of Distributions” for additional information). We intend to continue to adhere to these requirements and maintain the Company’s REIT status. Accordingly, no provision for income taxes has been made in the accompanying financial statements. In addition, any taxable income from our taxable REIT subsidiaries, which were formed in 2002, 2018 and 2019, are subject to federal, state, and local income taxes. For the years ended December 31, 2019 , 2018 and 2017 the taxable REIT subsidiaries had de minimis taxable income.
Uncertain Tax Positions	Uncertain Tax Positions We include favorable tax positions in the calculation of tax liabilities if it is more likely than not that our adopted tax position will prevail if challenged by tax authorities. We evaluated the potential impact of identified uncertain tax positions for all tax years still subject to audit under state and federal income tax law and concluded that we did not have any unrecognized tax benefits or any additional tax liabilities as of December 31, 2019 or 2018 . As of December 31, 2019 , the years still subject to audit are 2015 through 2019 under the California state income tax law and 2016 through 2019 under the federal income tax law.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.
Segments	Segments We currently operate in one operating segment, our office properties segment.
Concentration of Credit Risk	Concentration of Credit Risk All of our properties and development and redevelopment projects are owned and all of our business is currently conducted in the state of California with the exception of the ownership and operation of eight office properties, one development project under construction and one recently acquired future development project located in the state of Washington. The ability of tenants to honor the terms of their leases is dependent upon the economic, regulatory, and social factors affecting the communities in which our tenants operate.

Organization and Ownership (Tab

Organization and Ownership (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of real estate properties	As of December 31, 2019 , the following properties were excluded from our stabilized portfolio. We did not have any redevelopment properties or properties held for sale at December 31, 2019 . Number of Properties/Projects Estimated Rentable Square Feet (1) / Units (unaudited) In-process development projects - tenant improvement (2) 2 846,000 In-process development projects - under construction (3) 6 2,291,000 Completed residential development project (4) 1 237 units _______________ (1) Estimated rentable square feet upon completion. (2) Includes 96,000 square feet of retail space. (3) In addition to the estimated office and life science rentable square feet noted above, development projects under construction also include 564 residential units. (4) Represents recently completed residential units not yet stabilized. Our stabilized portfolio of operating properties was comprised of the following properties at December 31, 2019 : Number of Buildings Rentable Square Feet (unaudited) Number of Tenants Percentage Occupied (unaudited) Percentage Leased (unaudited) Stabilized Office Properties 112 13,475,795 451 94.6 % 97.0 % Number of Number of Units 2019 Average Occupancy Stabilized Residential Property 1 200 82.4 %

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Basis of Presentation and Significant Accounting Policies [Abstract]
Schedule of allocation of rental income between fixed and variable payments	The table below sets forth the allocation of rental income between fixed and variable payments for the year ended December 31, 2019 : Year Ended December 31, 2019 (in thousands) Fixed lease payments $ 710,557 Variable lease payments 115,915 Total rental income $ 826,472
Buildings, improvements, and tenant improvements depreciation	The costs of buildings and improvements and tenant improvements are depreciated using the straight-line method of accounting over the estimated useful lives set forth in the table below. Depreciation expense for buildings and improvements for the three years ended December 31, 2019 , 2018 , and 2017 was $211.9 million , $198.6 million , and $190.5 million , respectively. Asset Description Depreciable Lives Buildings and improvements 25 – 40 years Tenant improvements 1 – 20 years (1) ________________________ (1)

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2019
Asset Acquisitions [Abstract]
Schedule of Acquisitions	The acquisitions were funded from various sources of liquidity including proceeds from the Company’s unsecured revolving credit facility, the issuance of debt and the settlement of the Company’s 2018 forward equity sales agreements. During the year ended December 31, 2018 , we acquired a development site adjacent to the three operating properties we acquired in January 2018, from an unrelated third party. The acquisition was funded with proceeds from the Company’s unsecured revolving credit facility and the Company’s at-the-market stock offering program. Project Date of Acquisition City/Submarket Purchase Price (in millions) 2019 Acquisitions 1335 Broadway & 901 Park Boulevard, San Diego, CA (1) August 19, 2019 East Village $ 40.0 Seattle CBD Project (2) December 12, 2019 Seattle CBD 133.0 Total 2019 Acquisitions $ 173.0 2018 Acquisitions Kilroy Oyster Point (3) June 1, 2018 South San Francisco $ 308.2 Total 2018 Acquisitions $ 308.2 ________________________ (1) Excludes acquisition-related costs. In connection with this acquisition, we also recorded $4.0 million in accrued liabilities and environmental remediation liabilities at the date of acquisition, which are not included in the purchase price above. As of December 31, 2019 , the purchase price and our current estimate of assumed liabilities are included in undeveloped land and construction in progress and the assumed liabilities are included in accounts payable, accrued expenses and other liabilities on the Company’s consolidated balance sheets. (2) Excludes acquisition-related costs. In connection with this acquisition, we also recorded $6.3 million in accrued liabilities and environmental remediation liabilities at the date of acquisition, which are not included in the purchase price above. As of December 31, 2019 , the purchase price and our current estimate of assumed liabilities are included in undeveloped land and construction in progress and the assumed liabilities are included in accounts payable, accrued expenses and other liabilities on the Company’s consolidated balance sheets. In addition, as of December 31, 2019 , the Company had $10.0 million in restricted cash, which is excluded from the purchase price above, related to this acquisition which may be payable to the seller only if certain events occur within three years following the date of acquisition. (3) Excludes acquisition-related costs. In connection with this acquisition, we also recorded $40.6 million in accrued liabilities and environmental remediation liabilities at the date of acquisition, which are not included in the purchase price above. As of December 31, 2018 , the purchase price and our current estimate of assumed liabilities are included in undeveloped land and construction in progress and the assumed liabilities are included in accounts payable, accrued expenses and other liabilities on the Company’s consolidated balance sheets. December 31, 2019 , we acquired the 19 -building creative office campus listed below in one transaction from an unrelated third party. During the year ended December 31, 2018 , we acquired the four operating properties listed below in two transactions from unrelated third parties. Property Date of Acquisition Number of Buildings Rentable Square Feet (unaudited) Occupancy as of December 31, 2019 (unaudited) Purchase Price (in millions) (1) 2019 Acquisitions 3101-3243 La Cienega Boulevard, Culver City, CA (2) October 15, 2019 19 151,908 100.0 % $ 186.0 2018 Acquisitions 345, 347 & 349 Oyster Point Boulevard, South San Francisco, CA January 31, 2018 3 145,530 100.0 % $ 111.0 345 Brannan Street, San Francisco, CA (3) December 21, 2018 1 110,050 99.7 % 146.0 Total (4) 4 255,580 $ 257.0 ________________________ (1) Excludes acquisition-related costs. (2) The results of operations for the properties acquired during 2019 contributed $3.7 million to revenue and a net loss of $0.1 million primarily due to a write-off of lease-related intangible assets as a result of an early lease termination. (3) At December 31, 2018 , this property was temporarily being held in a separate VIE to facilitate potential Section 1031 Exchanges. During January 2019, the Company completed the Section 1031 Exchange related to this VIE. (4) The results of operations for the properties acquired during 2018 contributed $8.0 million and $1.7 million to revenue and net income, respectively, for the year ended December 31, 2018 .
Schedule of estimated fair values of the assets acquired and liabilities assumed	The related assets, liabilities and results of operations of the acquired properties are included in the consolidated financial statements as of the date of acquisition. The following table summarizes the estimated fair values of the assets and liabilities assumed at the respective acquisition dates for our 2019 and 2018 operating property acquisitions, respectively: Total 2019 Operating Property Acquisitions (1) Total 2018 Operating Property Acquisitions (2) Assets Land and improvements $ 150,561 $ 80,269 Buildings and improvements (3) 30,932 172,059 Deferred leasing costs and acquisition-related intangible assets (4) 12,063 13,593 Right of use ground lease asset (5) 13,334 — Total assets acquired $ 206,890 $ 265,921 Liabilities Acquisition-related intangible liabilities (6) $ 9,950 $ 8,921 Ground lease liability (5) 10,940 — Total liabilities assumed $ 20,890 $ 8,921 Net assets and liabilities acquired $ 186,000 $ 257,000 ________________________ (1) The purchase price of the acquisition completed during the year ended December 31, 2019 was less than 10% of the Company’s total assets as of December 31, 2018 . (2) The purchase price of the two acquisitions completed during the year ended December 31, 2018 were individually less than 5% and in aggregate less than 10% of the Company’s total assets as of December 31, 2017 . (3) Represents buildings, building improvements and tenant improvements. (4) For the 2019 operating property acquisition, represents in-place leases (approximately $9.2 million with a weighted average amortization period of 3.3 years ) and leasing commissions (approximately $2.9 million with a weighted average amortization period of 3.5 years ). For the 2018 operating property acquisitions, represents in-place leases (approximately $11.8 million with a weighted average amortization period of 1.3 years ) and leasing commissions (approximately $1.8 million with a weighted average amortization period of 6.6 years ). (5) We evaluated the ground lease assumed in connection with the 2019 operating property acquisition and concluded it met the criteria to be classified as an operating lease. The discount rate used in determining the present value of the minimum future lease payments was 4.79% . The right of use asset ground lease asset is equal to the ground lease liability adjusted for above and below market intangibles and deferred leasing costs. Refer to Note 18 “Commitments and Contingencies” for further discussion of the Company's ground lease obligations. (6) For the 2019 operating property acquisition, represents below-market leases (approximately $10.0 million with a weighted average amortization period of 3.5 years ). For the 2018 operating property acquisitions, represents below-market leases (approximately $8.9 million with a weighted average amortization period of 9.8 years ).

Dispositions (Tables)

Dispositions (Tables)	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Schedule operating properties and land dispositions	The following table summarizes the operating properties sold during the years ended December 31, 2019 , 2018 and 2017 : Location Month of Disposition Number of Buildings Rentable Square Feet (unaudited) Sales Price (in millions) (1) 2019 Dispositions 2829 Townsgate Road, Thousand Oaks, CA May 1 84,098 $ 18.3 2211 Michelson Drive, Irvine, CA October 1 271,556 115.5 Total 2019 Dispositions 2 355,654 $ 133.8 2018 Dispositions 1310-1327 Chesapeake Terrace, Sunnyvale, CA November 4 266,982 $ 160.3 Plaza Yarrow Bay Properties (2) November 4 279,924 134.5 23925, 23975, & 24025 Park Sorrento, Calabasas, CA December 3 225,340 78.2 Total 2018 Dispositions 11 772,246 $ 373.0 2017 Dispositions 5717 Pacific Center Boulevard, San Diego, CA January 1 67,995 $ 12.1 Sorrento Mesa and Mission Valley Properties (3) September 10 675,143 174.5 Total 2017 Dispositions 11 743,138 $ 186.6 __________________ (1) Represents gross sales price before broker commissions and closing costs. (2) The Plaza Yarrow Bay Properties include the following properties: 10210, 10220 and 10230 NE Points Drive & 3933 Lake Washington Boulevard NE in Kirkland, Washington. (3) The Sorrento Mesa and Mission Valley Properties includes the following properties: 10390, 10394, 10398, 10421, 10445 and 10455 Pacific Center Court, 2355, 2365, 2375 and 2385 Northside Drive and Pacific Corporate Center - Lot 8, a 5.0 acre undeveloped land parcel.

Deferred Leasing Costs and Ac_2

Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of identified deferred leasing costs and acquisition-related intangible assets	The following table summarizes our deferred leasing costs and acquisition-related intangible assets (acquired value of leasing costs, above-market operating leases, in-place leases and below-market ground lease obligation) and intangible liabilities (acquired value of below-market operating leases and above-market ground lease obligation) as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Deferred Leasing Costs and Acquisition-related Intangible Assets, net: Deferred leasing costs $ 286,026 $ 266,905 Accumulated amortization (100,145 ) (100,805 ) Deferred leasing costs, net 185,881 166,100 Above-market operating leases 611 2,836 Accumulated amortization (116 ) (2,150 ) Above-market operating leases, net 495 686 In-place leases 58,076 66,526 Accumulated amortization (31,647 ) (36,174 ) In-place leases, net 26,429 30,352 Below-market ground lease obligation — 490 Accumulated amortization — (54 ) Below-market ground lease obligation, net (1) — 436 Total deferred leasing costs and acquisition-related intangible assets, net $ 212,805 $ 197,574 Acquisition-related Intangible Liabilities, net: (2) Below-market operating leases $ 51,263 $ 53,523 Accumulated amortization (27,171 ) (29,978 ) Below-market operating leases, net 24,092 23,545 Above-market ground lease obligation — 6,320 Accumulated amortization — (727 ) Above-market ground lease obligation, net (1) — 5,593 Total acquisition-related intangible liabilities, net $ 24,092 $ 29,138 _______________ (1) Upon adoption of Topic 842 on January 1, 2019 (refer to Note 2 “Basis of Presentation and Significant Accounting Policies”), we no longer separately recognize above or below-market ground lease obligations. Such amounts are reflected in the net book value of the right of use ground lease asset on our consolidated balance sheets. Refer to Note 18 “Commitments and Contingencies” for further discussion of our ground lease obligations. (2) Included in deferred revenue and acquisition-related intangible liabilities, net in the consolidated balance sheets.
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	The following table sets forth amortization related to deferred leasing costs and acquisition-related intangibles for the years ended December 31, 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 (in thousands) Deferred leasing costs (1) $ 35,779 $ 34,341 $ 31,675 Above-market operating leases (2) 192 444 2,240 In-place leases (1) 18,615 15,915 18,650 Below-market ground lease obligation (3) — 8 8 Below-market operating leases (4) (9,398 ) (10,192 ) (10,768 ) Above-market ground lease obligation (3) — (101 ) (101 ) Total $ 45,188 $ 40,415 $ 41,704 _______________ (1) The amortization of deferred leasing costs and in-place leases is recorded to depreciation and amortization expense and the amortization of lease incentives is recorded as a reduction to rental income in the consolidated statements of operations for the periods presented. (2) The amortization of above-market operating leases is recorded as a decrease to rental income in the consolidated statements of operations for the periods presented. (3) Upon adoption of Topic 842 on January 1, 2019 (refer to Note 2 “Basis of Presentation and Significant Accounting Policies”), we no longer separately recognize above or below-market ground lease obligations. Refer to Note 18 “Commitments and Contingencies” for further discussion of our ground lease obligations. (4) The amortization of below-market operating leases is recorded as an increase to rental income in the consolidated statements of operations for the periods presented.
Estimated annual amortization related to deferred leasing costs and acquisition-related intangibles	The following table sets forth the estimated annual amortization expense related to deferred leasing costs and acquisition-related intangibles as of December 31, 2019 for future periods: Year Deferred Leasing Costs Above-Market Operating Leases (1) In-Place Leases Below-Market Operating Leases (2) (in thousands) 2020 30,897 38 11,379 (7,258 ) 2021 27,043 38 6,668 (4,543 ) 2022 23,642 38 4,001 (3,553 ) 2023 19,904 38 1,641 (1,866 ) 2024 16,976 38 602 (1,090 ) Thereafter 67,419 305 2,138 (5,782 ) Total $ 185,881 $ 495 $ 26,429 $ (24,092 ) _______________ (1) Represents estimated annual amortization related to above-market operating leases. Amounts will be recorded as a decrease to rental income in the consolidated statements of operations. (2) Represents estimated annual amortization related to below-market operating leases. Amounts will be recorded as an increase to rental income in the consolidated statements of operations.

Receivables (Tables)

Receivables (Tables)	12 Months Ended
	Dec. 31, 2019
Receivables [Abstract]
Current receivables, net	Current receivables, net is primarily comprised of contractual rents and other lease-related obligations due from tenants. The balance consisted of the following as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Current receivables $ 27,660 $ 24,815 Allowance for uncollectible tenant receivables (1) (1,171 ) (4,639 ) Current receivables, net $ 26,489 $ 20,176
Deferred rent receivables, net	Deferred rent receivables, net consisted of the following as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Deferred rent receivables $ 339,489 $ 270,346 Allowance for deferred rent receivables (1) (1,552 ) (3,339 ) Deferred rent receivables, net $ 337,937 $ 267,007

Prepaid Expenses and Other As_2

Prepaid Expenses and Other Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid expenses and other assets, net	Prepaid expenses and other assets, net consisted of the following at December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Furniture, fixtures and other long-lived assets, net $ 35,286 $ 36,833 Notes receivable (1) 1,651 2,113 Prepaid expenses 18,724 13,927 Total prepaid expenses and other assets, net $ 55,661 $ 52,873 _______________ (1) Notes receivable are shown net of a valuation allowance of approximately $3.6 million and $2.9 million as of December 31, 2019 and 2018 , respectively.

Secured and Unsecured Debt of_3

Secured and Unsecured Debt of the Operating Partnership (Tables) - Kilroy Realty L.P. [Member]	12 Months Ended
	Dec. 31, 2019
Debt Instrument [Line Items]
Unsecured revolving credit facility	The following table summarizes the balance and terms of our unsecured revolving credit facility as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Outstanding borrowings $ 245,000 $ 45,000 Remaining borrowing capacity 505,000 705,000 Total borrowing capacity (1) $ 750,000 $ 750,000 Interest rate (2) 2.76 % 3.48 % Facility fee-annual rate (3) 0.200% Maturity date July 2022 _______________ (1) We may elect to borrow, subject to bank approval and obtaining commitments for any additional borrowing capacity, up to an additional $600.0 million under an accordion feature under the terms of the unsecured revolving credit facility and unsecured term loan facility. (2) Our unsecured revolving credit facility interest rate was calculated based on the contractual rate of LIBOR plus 1.000% as of December 31, 2019 and 2018 . (3) Our facility fee is paid on a quarterly basis and is calculated based on the total borrowing capacity. In addition to the facility fee, we incurred debt origination and legal costs. As of December 31, 2019 and 2018 , $3.4 million and $4.7 million December 31, 2019 and 2018 , which is included in unsecured debt, net on our consolidated balance sheets: December 31, 2019 December 31, 2018 (in thousands) Outstanding borrowings $ 150,000 $ 150,000 Remaining borrowing capacity — — Total borrowing capacity (1) $ 150,000 $ 150,000 Interest rate (2) 2.85 % 3.49 % Undrawn facility fee-annual rate 0.200% Maturity date July 2022 _______________ (1) As of December 31, 2019 and 2018 , $0.7 million and $0.9 million of unamortized deferred financing costs, respectively, remained to be amortized through the maturity date of our unsecured term loan facility. (2) Our unsecured term loan facility interest rate was calculated based on the contractual rate of LIBOR plus 1.100% as of December 31, 2019 and 2018 .
Schedule of debt maturities	The following table summarizes the stated debt maturities and scheduled amortization payments as of December 31, 2019 : Year (in thousands) 2020 $ 5,137 2021 5,342 2022 400,554 2023 305,775 2024 431,006 Thereafter 2,431,688 Total aggregate principal value (1) $ 3,579,502 ________________________ (1) Includes gross principal balance of outstanding debt before the effect of the following at December 31, 2019 : $20.3 million of unamortized deferred financing costs for the unsecured term loan facility, unsecured senior notes and secured debt and $6.5 million of unamortized discounts for the unsecured senior notes.
Capitalized interest and loan fees	The following table sets forth gross interest expense, including debt discount/premium and deferred financing cost amortization, net of capitalized interest, for the years ended 2019 , 2018 and 2017 . The interest expense capitalized was recorded as a cost of development and increased the carrying value of undeveloped land and construction in progress. Year Ended December 31, 2019 2018 2017 (in thousands) Gross interest expense $ 129,778 $ 117,789 $ 112,577 Capitalized interest and deferred financing costs (81,241 ) (68,068 ) (46,537 ) Interest expense $ 48,537 $ 49,721 $ 66,040
Secured debt [Member]
Debt Instrument [Line Items]
Debt balance and significant terms	The following table sets forth the composition of our secured debt as of December 31, 2019 and 2018 : Annual Stated Interest Rate (1) GAAP Effective Rate (1)(2) Maturity Date December 31, Type of Debt 2019 2018 (in thousands) Mortgage note payable 3.57% 3.57% December 2026 $ 170,000 $ 170,000 Mortgage note payable (3) 4.48% 4.48% July 2027 89,502 91,332 Mortgage note payable (3)(4) 6.05% 3.50% June 2019 — 75,238 Total secured debt $ 259,502 $ 336,570 Unamortized Deferred Financing Costs (909 ) (1,039 ) Total secured debt, net $ 258,593 $ 335,531 ______________ (1) All interest rates presented are fixed-rate interest rates. (2) Represents the effective interest rate including the amortization of initial issuance discounts/premiums excluding the amortization of deferred financing costs. (3) The secured debt and the related properties that secure the debt are held in a special purpose entity and the properties are not available to satisfy the debts and other obligations of the Company or the Operating Partnership. (4) In February 2019, the Company repaid this mortgage note payable at par.
Unsecured senior notes [Member]
Debt Instrument [Line Items]
Debt balance and significant terms	The following table summarizes the balance and significant terms of the registered unsecured senior notes issued by the Operating Partnership and outstanding, including unamortized discounts of $6.5 million and $6.6 million and unamortized deferred financing costs of $18.7 million and $15.4 million as of December 31, 2019 and 2018 , respectively: Net Carrying Amount Issuance date Maturity date Stated coupon rate Effective interest rate (1) 2019 2018 (in thousands) 3.050% Unsecured Senior Notes (2) September 2019 February 2030 3.050% 3.064% $ 500,000 $ — Unamortized discount and deferred financing costs (5,998 ) — Net carrying amount $ 494,002 $ — 4.750% Unsecured Senior Notes (3) November 2018 December 2028 4.750% 4.800% $ 400,000 $ 400,000 Unamortized discount and deferred financing costs (4,446 ) (4,960 ) Net carrying amount $ 395,554 $ 395,040 4.350% Unsecured Senior Notes (4) October 2018 October 2026 4.350% 4.350% $ 200,000 $ 200,000 Unamortized discount and deferred financing costs (1,186 ) (1,375 ) Net carrying amount $ 198,814 $ 198,625 4.300% Unsecured Senior Notes (4) July 2018 July 2026 4.300% 4.300% $ 50,000 $ 50,000 Unamortized discount and deferred financing costs (290 ) (342 ) Net carrying amount $ 49,710 $ 49,658 3.450% Unsecured Senior Notes (5) December 2017 December 2024 3.450% 3.470% $ 425,000 $ 425,000 Unamortized discount and deferred financing costs (2,907 ) (3,493 ) Net carrying amount $ 422,093 $ 421,507 3.450% Unsecured Senior Notes (6) February 2017 February 2029 3.450% 3.450% $ 75,000 $ 75,000 Unamortized discount and deferred financing costs (390 ) (432 ) Net carrying amount $ 74,610 $ 74,568 3.350% Unsecured Senior Notes (6) February 2017 February 2027 3.350% 3.350% $ 175,000 $ 175,000 Unamortized discount and deferred financing costs (825 ) (941 ) Net carrying amount $ 174,175 $ 174,059 4.375% Unsecured Senior Notes (7) September 2015 October 2025 4.375% 4.444% $ 400,000 $ 400,000 Unamortized discount and deferred financing costs (3,185 ) (3,738 ) Net carrying amount $ 396,815 $ 396,262 4.250% Unsecured Senior Notes (8) July 2014 August 2029 4.250% 4.350% $ 400,000 $ 400,000 Unamortized discount and deferred financing costs (5,100 ) (5,632 ) Net carrying amount $ 394,900 $ 394,368 3.800% Unsecured Senior Notes (9) January 2013 January 2023 3.800% 3.800% $ 300,000 $ 300,000 Unamortized discount and deferred financing costs (834 ) (1,108 ) Net carrying amount $ 299,166 $ 298,892 Total Unsecured Senior Notes, Net $ 2,899,839 $ 2,402,979 ________________________ (1) Represents the effective interest rate including the amortization of initial issuance discounts, excluding the amortization of deferred financing costs. (2) Interest on these notes is payable semi-annually in arrears on February 15th and August 15th of each year, beginning on February 15, 2020. (3) Interest on these notes is payable semi-annually in arrears on June 15th and December 15th of each year. (4) Interest on these notes is payable semi-annually in arrears on April 18th and October 18th of each year. (5) Interest on these notes is payable semi-annually in arrears on June 15th and December 15th of each year. (6) Interest on these notes is payable semi-annually in arrears on February 17th and August 17th of each year. (7) Interest on these notes is payable semi-annually in arrears on April 1st and October 1st of each year. (8) Interest on these notes is payable semi-annually in arrears on February 15th and August 15th of each year. (9) Interest on these notes is payable semi-annually in arrears on January 15th and July 15th of each year.

Deferred Revenue and Acquisit_2

Deferred Revenue and Acquisition-Related Intangible Liabilities, net (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Deferred revenue and acquisition-related liabilities	Deferred revenue and acquisition-related intangible liabilities, net consisted of the following at December 31, 2019 and 2018 : December 31, 2019 2018 (in thousands) Deferred revenue related to tenant-funded tenant improvements $ 96,271 $ 104,558 Other deferred revenue 19,125 15,950 Acquisition-related intangible liabilities, net (1) 24,092 29,138 Total $ 139,488 $149,646 ________________________ (1) See Note 5 “Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net” for additional information regarding our acquisition-related intangible liabilities.
Estimated amortization of deferred revenue related to tenant-funded improvements	The following is the estimated amortization of deferred revenue related to tenant-funded tenant improvements as of December 31, 2019 for the next five years and thereafter: Year Ending (in thousands) 2020 $ 16,935 2021 15,426 2022 14,320 2023 12,553 2024 10,318 Thereafter 26,719 Total $ 96,271

Stockholders' Equity of the C_2

Stockholders' Equity of the Company (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of common stock sales under the at-the-market offering	The following table sets forth information regarding direct sales of our common stock under our at-the-market offering programs for the years ended December 31, 2018 and 2017 : Year Ended December 31, 2018 2017 (in millions, except share data) Shares of common stock sold during the period 1,817,195 235,077 Weighted average price per share of common stock $ 73.64 $ 75.40 Aggregate gross proceeds $ 133.8 $ 17.7 Aggregate net proceeds after selling commissions $ 132.1 $ 17.5
Schedule of accrued dividends and distributions	The following tables summarize accrued dividends and distributions for the noted outstanding shares of common stock and noncontrolling units as of December 31, 2019 and 2018 : December 31, 2019 2018 (in thousands) Dividends and Distributions payable to: Common stockholders $ 51,418 $ 45,840 Noncontrolling common unitholders of the Operating Partnership 981 922 RSU holders (1) 820 797 Total accrued dividends and distribution to common stockholders and noncontrolling unitholders $ 53,219 $ 47,559 ______________________ (1) The amount includes the value of the dividend equivalents that will be paid with additional RSUs (see Note 15 “Share-Based Compensation” for additional information).
Schedule of outstanding shares of common stock, preferred stock and noncontrolling units	December 31, 2019 2018 Outstanding Shares and Units: Common stock (1) 106,016,287 100,746,988 Noncontrolling common units 2,023,287 2,025,287 RSUs (2) 1,651,905 1,711,628 ______________________ (1) The amount includes nonvested shares. (2) The amount includes nonvested RSUs. Does not include 932,675 and 1,018,337 market measure-based RSUs because not all the necessary performance conditions have been met as of December 31, 2019 and 2018 , respectively. Refer to Note 15 “Share-Based Compensation” for additional information.

Partners' Capital of the Oper_2

Partners' Capital of the Operating Partnership (Tables)	12 Months Ended
	Dec. 31, 2019
Class of Stock [Line Items]
Schedule of common stock sales under the at-the-market offering	The following table sets forth information regarding direct sales of our common stock under our at-the-market offering programs for the years ended December 31, 2018 and 2017 : Year Ended December 31, 2018 2017 (in millions, except share data) Shares of common stock sold during the period 1,817,195 235,077 Weighted average price per share of common stock $ 73.64 $ 75.40 Aggregate gross proceeds $ 133.8 $ 17.7 Aggregate net proceeds after selling commissions $ 132.1 $ 17.5
Schedule of accrued dividends and distributions	The following tables summarize accrued dividends and distributions for the noted outstanding shares of common stock and noncontrolling units as of December 31, 2019 and 2018 : December 31, 2019 2018 (in thousands) Dividends and Distributions payable to: Common stockholders $ 51,418 $ 45,840 Noncontrolling common unitholders of the Operating Partnership 981 922 RSU holders (1) 820 797 Total accrued dividends and distribution to common stockholders and noncontrolling unitholders $ 53,219 $ 47,559 ______________________ (1) The amount includes the value of the dividend equivalents that will be paid with additional RSUs (see Note 15 “Share-Based Compensation” for additional information).
Schedule of outstanding shares of common stock, preferred stock and noncontrolling units	December 31, 2019 2018 Outstanding Shares and Units: Common stock (1) 106,016,287 100,746,988 Noncontrolling common units 2,023,287 2,025,287 RSUs (2) 1,651,905 1,711,628 ______________________ (1) The amount includes nonvested shares. (2) The amount includes nonvested RSUs. Does not include 932,675 and 1,018,337 market measure-based RSUs because not all the necessary performance conditions have been met as of December 31, 2019 and 2018 , respectively. Refer to Note 15 “Share-Based Compensation” for additional information.
Kilroy Realty L.P. [Member]
Class of Stock [Line Items]
Schedule of common stock sales under the at-the-market offering	During the years ended December 31, 2018 and 2017 , the Company utilized its at-the-market stock offering programs to issue shares of common stock. See Note 13 “Stockholders’ Equity of the Company” for additional information. The net offering proceeds contributed by the Company to the Operating Partnership in exchange for common units for the years ended December 31, 2019 , 2018 and 2017 are as follows: Year Ended December 31, 2018 2017 (in millions, except share and per share data) Shares of common stock contributed by the Company 1,817,195 235,077 Common units exchanged for shares of common stock by the Company 1,817,195 235,077 Aggregate gross proceeds $ 133.8 $ 17.7 Aggregate net proceeds after selling commissions $ 132.1 $ 17.5
Redeemable noncontrolling interest	The following table sets forth the number of common units held by the Company and the number of common units held by non-affiliated investors and certain of our executive officers and directors in the form of noncontrolling common units as well as the ownership interest held on each respective date: December 31, 2019 December 31, 2018 Company owned common units in the Operating Partnership 106,016,287 100,746,988 Company owned general partnership interest 98.1 % 98.0 % Noncontrolling common units of the Operating Partnership 2,023,287 2,025,287 Ownership interest of noncontrolling interest 1.9 % 2.0 %
Schedule of accrued dividends and distributions	The following tables summarize accrued distributions for the noted common units as of December 31, 2019 and 2018 : December 31, 2019 December 31, 2018 (in thousands) Distributions payable to: General partner $ 51,418 $ 45,840 Common limited partners 981 922 RSU holders (1) 820 797 Total accrued distributions to common unitholders $ 53,219 $ 47,559 ______________________ (1) The amount includes the value of the dividend equivalents that will be paid with additional RSUs (see Note 15 “Share-Based Compensation” for additional information).
Schedule of outstanding shares of common stock, preferred stock and noncontrolling units	December 31, 2019 December 31, 2018 Outstanding Units: Common units held by the general partner 106,016,287 100,746,988 Common units held by the limited partners 2,023,287 2,025,287 RSUs (1) 1,651,905 1,711,628 ______________________ (1) Does not include 932,675 and 1,018,337 market measure-based RSUs because not all the necessary performance conditions have been met as of December 31, 2019 and 2018

Share-Based and Other Compens_2

Share-Based and Other Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of Restricted Stock Units Valuation Assumptions	As of December 31, 2019 , the estimated number of RSUs earned for the 2019 and 2018 Performance-Based RSUs and the actual number of RSUs earned for the 2017 Performance-Based RSUs was as follows: 2019 Performance-Based RSUs 2018 Performance-Based RSUs 2017 Performance-Based RSUs Service vesting period February 1, 2019 - January, 2022 February 14, 2018 - January, 2021 February 24, 2017 - January, 2020 Target RSUs granted 143,396 158,205 130,956 Estimated RSUs earned (1) 229,095 262,242 142,581 Date of valuation February 1, 2019 February 14, 2018 February 24, 2017 _______________ (1) Estimated RSUs earned for the 2019 Performance-Based RSUs are based on the actual achievement of the 2019 FFO Performance Condition and for the 2019 Debt to EBITDA Ratio Performance Condition, assumes 125% of the target level of achievement for one participant and 117% of the target level of achievement for all other participants, and target level of achievement of the 2019 Market Condition. Estimated RSUs earned for the 2018 Performance-Based RSUs are based on the actual achievement of the 2018 FFO Performance Condition and assume target level achievement of the 2018 Market Condition and maximum level of achievement of the 2018 Debt to EBITDA Ratio Performance Condition. The 2017 Performance-Based RSUs earned are based on actual performance of the 2017 Performance Conditions and the 2017 Market Condition. 2019 Time-Based RSU Grant December 2018 Time-Based RSU Grant 2018 Time-Based RSU Grant (1) 2017 Time-Based RSU Grant (2) Service vesting period February 1, 2019 - January 5, 2022 December 27, 2018 - January 5, 2023 January & February 2018 - January 5, 2021 February 2017 - January 5, 2020 Fair value on valuation date (in millions) $ 10.1 $ 18.5 $ 8.4 $ 7.5 Fair value per share $ 69.89 $ 62.00 $ 70.37 $ 73.30 Date of fair valuation February 1, 2019 December 27, 2018 January & February 2018 February 2017 _______________ (1) The 2018 Time-Based RSUs consist of 56,015 RSUs granted on January 29, 2018 at a fair value per share of $70.37 and 67,818 RSUs granted on February 14, 2018 at a fair value per share of $66.46 . (2) The 2017 Time-Based RSUs consist of 41,119 RSUs granted on February 3, 2017 at a fair value per share of $73.30 and 57,901 RSUs granted on February 24, 2017 at a fair value per share of $77.16 .
Summary of Nonvested Restricted Stock	A summary of our nonvested and vested restricted stock activity for years ended December 31, 2018 and 2017 is presented below: Shares Granted Shares Vested Years ended December 31, Nonvested Shares Issued Weighted-Average Grant Date Fair Value Per Share Vested Shares Total Fair Value at Vest Date (1) (in thousands) 2018 — — (22,884 ) 1,652 2017 — — (24,261 ) 1,781 _______________ (1) Total fair value of shares vested was calculated based on the quoted closing share price of the Company’s common stock on the NYSE on the date of vesting.
Summary of Nonvested and Vested Restricted Stock Activity	A summary of our nonvested and vested restricted stock activity for years ended December 31, 2018 and 2017 is presented below: Shares Granted Shares Vested Years ended December 31, Nonvested Shares Issued Weighted-Average Grant Date Fair Value Per Share Vested Shares Total Fair Value at Vest Date (1) (in thousands) 2018 — — (22,884 ) 1,652 2017 — — (24,261 ) 1,781 _______________ (1) Total fair value of shares vested was calculated based on the quoted closing share price of the Company’s common stock on the NYSE on the date of vesting.
December 2018 Market-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assumptions Utilized in the Monte Carlo Simulation Pricing Models	The following table summarizes the assumptions utilized in the Monte Carlo simulation pricing models: December 2018 Market-Based RSU Award Fair Value Assumptions Valuation date December 27, 2018 Fair value per share on valuation date $68.66 Expected share price volatility 23.0% Risk-free interest rate 2.4%
Market measure-based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Restricted Stock Units Award Activity	A summary of our performance and market-measure based RSU activity from January 1, 2019 through December 31, 2019 is presented below: Nonvested RSUs Vested RSUs Total RSUs Amount Weighted-Average Outstanding at January 1, 2019 1,018,337 $ 67.29 35,761 1,054,098 Granted 231,191 71.12 1,155 232,346 Vested (261,990 ) 57.08 261,990 — Settled (1) — (264,814 ) (264,814 ) Issuance of dividend equivalents (2) 23,254 74.11 2,592 25,846 Forfeited (78,117 ) 70.07 (5 ) (78,122 ) Outstanding as of December 31, 2019 (3) 932,675 $ 71.04 36,679 969,354 _______________ (1) Represents vested RSUs that were settled in shares of the Company’s common stock. Total shares settled include 125,220 shares that were tendered in accordance with the terms of the 2006 Plan to satisfy minimum statutory tax withholding requirements related to the RSUs settled. We accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy tax obligations. (2) Represents the issuance of dividend equivalents earned on the underlying RSUs. The dividend equivalents vest based on terms specified under the related RSU award agreement. (3) Outstanding RSUs as of December 31, 2019 represent the actual achievement of the FFO performance conditions and assumes target levels for the market and other performance conditions. The number of restricted stock units ultimately earned is subject to change based upon actual performance over the three-year vesting period. Dividend equivalents earned will vest along with the underlying award and are also subject to changes based on the number of RSUs ultimately earned for each underlying award. A summary of our performance and market-measure based RSU activity for the years ended December 31, 2019 , 2018 and 2017 is presented below: RSUs Granted RSUs Vested Years ended December 31, Non-Vested RSUs Granted (1) Weighted-Average Fair Value Per Share Vested RSUs Total Vest-Date Fair Value (in thousands) 2019 231,191 $ 71.12 (265,737 ) $ 18,703 2018 601,012 68.51 (265,918 ) 18,906 2017 170,994 78.97 (194,991 ) 14,270 _______________ (1) Non-vested RSUs granted are based on the actual achievement of the FFO performance conditions and assumes target level achievement for the market and other performance conditions.
Time-Based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Restricted Stock Units Award Activity	A summary of our time-based RSU activity from January 1, 2019 through December 31, 2019 is presented below: Nonvested RSUs Vested RSUs Total RSUs Amount Weighted Average Fair Value Outstanding at January 1, 2019 586,779 $ 65.87 1,089,088 1,675,867 Granted 153,005 70.31 — 153,005 Vested (153,464 ) 67.26 153,464 — Settled (1) (198,183 ) (198,183 ) Issuance of dividend equivalents (2) 13,341 74.72 28,755 42,096 Forfeited (55,813 ) 68.71 — (55,813 ) Canceled (3) (1,746 ) (1,746 ) Outstanding as of December 31, 2019 543,848 $ 66.66 1,071,378 1,615,226 _______________ (1) Represents vested RSUs that were settled in shares of the Company’s common stock. Total shares settled include 82,646 shares that were tendered in accordance with the terms of the 2006 Plan to satisfy minimum statutory tax withholding requirements related to the RSUs settled. We accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy tax obligations. (2) Represents the issuance of dividend equivalents earned on the underlying RSUs. The dividend equivalents vest based on terms specified under the related RSU award agreement. (3) For shares vested but not yet settled, we accept the return of RSUs at the current quoted closing share price of the Company’s common stock to satisfy minimum statutory tax-withholding requirements related to either the settlement or vesting of RSUs in accordance with the terms of the 2006 Plan. A summary of our time-based RSU activity for the years ended December 31, 2019 , 2018 and 2017 is presented below: RSUs Granted RSUs Vested Year ended December 31, Non-Vested RSUs Issued Weighted-Average Grant Date Fair Value Per Share Vested RSUs Total Vest-Date Fair Value (1) (in thousands) 2019 153,005 $ 70.31 (182,219 ) $ 12,277 2018 437,216 64.21 (214,131 ) 14,768 2017 142,101 74.91 (228,095 ) 16,735 _______________ (1) Total fair value of RSUs vested was calculated based on the quoted closing share price of the Company’s common stock on the NYSE on the day of vesting. Excludes the issuance of dividend equivalents earned on the underlying RSUs. The dividend equivalents vest based on terms specified under the related RSU award agreement.
2018, 2017, and 2016 Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Assumptions Utilized in the Monte Carlo Simulation Pricing Models	The following table summarizes the assumptions utilized in the Monte Carlo simulation pricing models: 2019 Award Fair Value Assumptions 2018 Award Fair Value Assumptions 2017 Award Fair Value Assumptions Valuation date February 1, 2019 February 14, 2018 February 24, 2017 Fair value per share on valuation date $72.57 $70.08 $80.89 Expected share price volatility 19.0% 20.0% 21.0% Risk-free interest rate 2.48% 2.37% 1.39%

Future Minimum Rent (Tables)

Future Minimum Rent (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Future contractual minimum rent under operating lease	Future contractual minimum rent under operating leases as of December 31, 2019 for future periods is summarized as follows: Year Ending (in thousands) 2020 $ 675,636 2021 728,736 2022 785,239 2023 769,294 2024 727,399 Thereafter 4,054,487 Total (1) $ 7,740,791 ______________ (1) Excludes residential leases and leases with a term of one year or less.
Future contractual minimum rent under operating lease	Future contractual minimum rent under operating leases as of December 31, 2018 for future periods is summarized as follows: Year Ending (in thousands) 2019 $ 566,783 2020 632,875 2021 631,835 2022 620,684 2023 586,371 Thereafter 3,240,143 Total (1) $ 6,278,691 ______________ (1) Excludes residential leases and leases with a term of one year or less.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of contractual expiration dates for ground leases	The following table summarizes our properties that are held subject to long-term noncancellable ground lease obligations and the respective contractual expiration dates: Property Contractual Expiration Date (1) 601 108th Ave NE, Bellevue, WA November 2093 701, 801 and 837 N. 34th Street, Seattle, WA (2) December 2041 1701 Page Mill Road and 3150 Porter Drive, Palo Alto, CA December 2067 Kilroy Airport Center Phases I, II, and III, Long Beach, CA July 2084 3243 S. La Cienega Boulevard, Los Angeles, CA (3) October 2106 ____________________ (1) Reflects the contractual expiration date prior to the impact of any extension or purchase options held by the Company. (2) The Company has three 10 -year and one 45 -year extension options for this ground lease, which if exercised would extend the expiration date to December 2116.
Schedule of minimum commitment under ground leases	The minimum commitment under our ground leases as of December 31, 2019 for five years and thereafter is as follows: Year Ending (in thousands) 2020 5,641 2021 5,641 2022 5,642 2023 5,662 2024 5,662 Thereafter 286,385 Total undiscounted cash flows (1)(2)(3)(4)(5)(6) $ 314,633 Present value discount (216,233 ) Ground lease liabilities $ 98,400 ________________________ (1) Excludes contingent future rent payments based on gross income or adjusted gross income and reflects the minimum ground lease obligations before the impact of ground lease extension options. (2) One of our ground lease obligations is subject to a fair market value adjustment every five years ; however, the lease includes ground rent subprotection and infrastructure rent credits which currently limit our annual rental obligations to $1.0 million . The contractual obligations for that ground lease included above assumes the lesser of $1.0 million or annual lease rental obligation in effect as of December 31, 2019 . (3) One of our ground lease obligations includes a component which is based on the percentage of gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every five years based on 50% of the average annual percentage rent for the previous five years. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2019 for the remainder of the lease term since we cannot predict future adjustments. (4) One of our ground lease obligations is subject to a fair market value adjustment every five years based on a combination of CPI adjustments and third-party appraisals limited to maximum increases annually. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2019 for the remainder of the lease term since we cannot predict future adjustments. (5) One of our ground lease obligations includes a component which is based on the percentage of adjusted gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every 10 years by an amount equal to 60% of the average annual percentage rent for the previous three years. The contractual obligations for this lease included above assume the current annual ground lease obligation in effect at December 31, 2019 for the remainder of the lease term since we cannot predict future adjustments. (6) One of our ground lease obligations is subject to fixed 5% ground rent increases every five years , with the next increase occurring on December 1, 2022.
Schedule of minimum commitment under ground leases	The minimum commitment under our ground leases as of December 31, 2018 for future periods is summarized as follows: Year Ending (in thousands) 2019 $ 5,154 2020 5,154 2021 5,154 2022 5,154 2023 5,154 Thereafter 233,619 Total (1)(2)(3)(4)(5) $ 259,389 ________________________ (1) Excludes contingent future rent payments based on gross income or adjusted gross income and reflects the minimum ground lease obligations before the impact of ground lease extension options. (2) One of our ground lease obligations is subject to a fair market value adjustment every five years ; however, the lease includes ground rent subprotection and infrastructure rent credits which currently limit our annual rental obligations to $1.0 million . The contractual obligations for that ground lease included above assumes the lesser of $1.0 million or annual lease rental obligation in effect as of December 31, 2018. (3) One of our ground lease obligations includes a component which is based on the percentage of gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every five years based on 50% of the average annual percentage rent for the previous five years. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2018 for the remainder of the lease term since we cannot predict future adjustments. (4) One of our ground lease obligations is subject to a fair market value adjustment every five years based on a combination of CPI adjustments and third-party appraisals limited to maximum increases annually. The contractual obligations for that lease included above assume the current annual ground lease obligation in effect at December 31, 2018 for the remainder of the lease term since we cannot predict future adjustments. (5) One of our ground lease obligations includes a component which is based on the percentage of adjusted gross income that exceeds the minimum ground rent. The minimum rent is subject to increases every ten years by an amount equal to 60% of the average annual percentage rent for the previous three years. The contractual obligations for this lease included above assume the current annual ground lease obligation in effect at December 31, 2018 for the remainder of the lease term since we cannot predict future adjustments.

Fair Value Measurements and D_2

Fair Value Measurements and Disclosures (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair value of the company's marketable securities	The following table sets forth the fair value of our marketable securities as of December 31, 2019 and 2018 : Fair Value (Level 1) (1) 2019 2018 Description (in thousands) Marketable securities (2) $ 27,098 $ 21,779 _______________ (1) Based on quoted prices in active markets for identical securities. (2) The marketable securities are held in a limited rabbi trust .
Net (loss) gain on marketable securities	The following table sets forth the net (loss) gain on marketable securities recorded during the years ended December 31, 2019 , 2018 and 2017 : December 31, 2019 2018 2017 Description (in thousands) Net gain (loss) on marketable securities $ 3,885 $ (1,851 ) $ 3,023
Carrying value and fair value of other financial instruments	The following table sets forth the carrying value and the fair value of our other financial instruments as of December 31, 2019 and 2018 : December 31, 2019 2018 Carrying Value Fair Value (1) Carrying Value Fair Value (1) (in thousands) Liabilities Secured debt, net $ 258,593 $ 272,997 $ 335,531 $ 335,885 Unsecured debt, net 3,049,185 3,252,217 2,552,070 2,546,386 Unsecured line of credit 245,000 245,195 45,000 45,058 _______________ (1) Fair value calculated using Level II inputs, which are based on model-derived valuations in which significant inputs and significant value drivers are observable in active markets.

Net Income Available to Commo_3

Net Income Available to Common Stockholders Per Share of the Company (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net income available to common stockholders	The following table reconciles the numerator and denominator in computing the Company’s basic and diluted per-share computations for net income available to common stockholders for the years ended December 31, 2019 , 2018 and 2017 : Year Ended December 31, 2019 2018 2017 (in thousands, except unit and per unit amounts) Numerator: Net income attributable to Kilroy Realty Corporation $ 195,443 $ 258,415 $ 164,612 Total preferred dividends — — (13,363 ) Allocation to participating securities (1) (2,119 ) (2,004 ) (1,975 ) Numerator for basic and diluted net income available to common stockholders $ 193,324 $ 256,411 $ 149,274 Denominator: Basic weighted average vested shares outstanding 103,200,568 99,972,359 98,113,561 Effect of dilutive securities 648,600 510,006 613,770 Diluted weighted average vested shares and common stock equivalents outstanding 103,849,168 100,482,365 98,727,331 Basic earnings per share: Net income available to common stockholders per share $ 1.87 $ 2.56 $ 1.52 Diluted earnings per share: Net income available to common stockholders per share $ 1.86 $ 2.55 $ 1.51 ________________________ (1) Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs.

Net Income Available to Commo_4

Net Income Available to Common Unitholders Per Unit of the Operating Partnership (Tables)	12 Months Ended
	Dec. 31, 2019
Net Income Available To Common Unitholders [Line Items]
Net income available to common unitholders	The following table reconciles the numerator and denominator in computing the Company’s basic and diluted per-share computations for net income available to common stockholders for the years ended December 31, 2019 , 2018 and 2017 : Year Ended December 31, 2019 2018 2017 (in thousands, except unit and per unit amounts) Numerator: Net income attributable to Kilroy Realty Corporation $ 195,443 $ 258,415 $ 164,612 Total preferred dividends — — (13,363 ) Allocation to participating securities (1) (2,119 ) (2,004 ) (1,975 ) Numerator for basic and diluted net income available to common stockholders $ 193,324 $ 256,411 $ 149,274 Denominator: Basic weighted average vested shares outstanding 103,200,568 99,972,359 98,113,561 Effect of dilutive securities 648,600 510,006 613,770 Diluted weighted average vested shares and common stock equivalents outstanding 103,849,168 100,482,365 98,727,331 Basic earnings per share: Net income available to common stockholders per share $ 1.87 $ 2.56 $ 1.52 Diluted earnings per share: Net income available to common stockholders per share $ 1.86 $ 2.55 $ 1.51 ________________________ (1) Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs.
Kilroy Realty L.P. [Member]
Net Income Available To Common Unitholders [Line Items]
Net income available to common unitholders	The following table reconciles the numerator and denominator in computing the Operating Partnership’s basic and diluted per-unit computations for net income available to common unitholders for the years ended 2019 , 2018 and 2017 : Year Ended December 31, 2019 2018 2017 (in thousands, except unit and per unit amounts) Numerator: Net income attributable to Kilroy Realty, L.P. $ 198,738 $ 263,210 $ 167,440 Total preferred distributions — — (13,363 ) Allocation to participating securities (1) (2,119 ) (2,004 ) (1,975 ) Numerator for basic and diluted net income available to common unitholders $ 196,619 $ 261,206 $ 152,102 Denominator: Basic weighted average vested units outstanding 105,223,975 102,025,276 100,246,567 Effect of dilutive securities 648,600 510,006 613,770 Diluted weighted average vested units and common unit equivalents outstanding 105,872,575 102,535,282 100,860,337 Basic earnings per unit: Net income available to common unitholders per unit $ 1.87 $ 2.56 $ 1.52 Diluted earnings per unit: Net income available to common unitholders per unit $ 1.86 $ 2.55 $ 1.51 ________________________ (1) Participating securities include nonvested shares, certain time-based RSUs and vested market measure-based RSUs.

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information of the Company (Tables)	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Schedule of supplemental cash flows	Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 13 and 28) $ 53,219 $ 47,559 $ 43,448 Exchange of common units of the Operating Partnership into shares of the Company’s common stock $ 78 $ 1,962 $ 10,939 Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common $ 53,219 $ 47,559 $ 43,448
Reconciliation of cash and cash equivalents and restricted cash	The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798 The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798

Supplemental Cash Flow Elements

Supplemental Cash Flow Elements (Tables)	12 Months Ended
	Dec. 31, 2019
Supplemental Cash Flow Elements [Abstract]
Schedule of supplemental cash flows, operating unit	Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 13 and 28) $ 53,219 $ 47,559 $ 43,448 Exchange of common units of the Operating Partnership into shares of the Company’s common stock $ 78 $ 1,962 $ 10,939 Supplemental cash flow information follows (in thousands): Year Ended December 31, 2019 2018 2017 SUPPLEMENTAL CASH FLOWS INFORMATION: Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively $ 43,607 $ 44,697 $ 67,336 Cash paid for amounts included in the measurement of ground lease liabilities $ 5,224 $ 4,398 $ 4,809 NON-CASH INVESTING TRANSACTIONS: Accrual for expenditures for operating properties and development properties $ 162,654 $ 158,626 $ 116,089 Assumption of accrued liabilities in connection with acquisitions (Note 3) $ 10,267 $ 40,624 $ 1,443 Tenant improvements funded directly by tenants $ 10,268 $ 13,968 $ 15,314 Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18) $ 96,272 $ — $ — Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18) $ 98,349 $ — $ — NON-CASH FINANCING TRANSACTIONS: Accrual of dividends and distributions payable to common stockholders and common $ 53,219 $ 47,559 $ 43,448
Reconciliation of cash and cash equivalents and restricted cash	The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798 The following is a reconciliation of our cash and cash equivalents and restricted cash at the beginning and end of the years ended 2019 , 2018 and 2017 . Year Ended December 31, 2019 2018 2017 RECONCILIATION OF CASH AND CASH EQUIVALENTS AND RESTRICTED CASH: Cash and cash equivalents at beginning of period $ 51,604 $ 57,649 $ 193,418 Restricted cash at beginning of period 119,430 9,149 56,711 Cash and cash equivalents and restricted cash at beginning of period $ 171,034 $ 66,798 $ 250,129 Cash and cash equivalents at end of period $ 60,044 $ 51,604 $ 57,649 Restricted cash at end of period 16,300 119,430 9,149 Cash and cash equivalents and restricted cash at end of period $ 76,344 $ 171,034 $ 66,798

Tax Treatment of Distributions

Tax Treatment of Distributions (Tables)	12 Months Ended
	Dec. 31, 2019
Class of Stock [Line Items]
Reconciliation of dividends declared to dividends paid	The following table reconciles the dividends declared per share of common stock to the dividends paid per share of common stock during the years ended December 31, 2019 , 2018 and 2017 as follows: Year Ended December 31, Dividends 2019 2018 2017 Dividends declared per share of common stock $ 1.910 $ 1.790 $ 1.650 Less: Dividends declared in the current year and paid in the following year (0.485 ) (0.455 ) (0.425 ) Add: Dividends declared in the prior year and paid in the current year (1) 0.455 0.425 2.275 Dividends paid per share of common stock $ 1.880 $ 1.760 $ 3.500 _________________ (1) The fourth quarter 2016 dividend of $2.275 per share of common stock consists of a special cash dividend of $1.90 per share of common stock and a regular quarterly cash dividend of $0.375 per share of common stock. The $1.90 per share special distribution is treated as paid in two tax years for income tax purposes: $1.587 is treated as paid on December 31, 2016 and $0.313 is treated as paid on January 13, 2017. The $0.375 per share regular quarterly distribution is considered a 2017 dividend distribution for income tax purposes.
Common Stock [Member]
Class of Stock [Line Items]
Reconciliation of dividends declared to dividends paid	The unaudited income tax treatment for the dividends to common stockholders reportable for the years ended December 31, 2019 , 2018 and 2017 as identified in the table above was as follows: Year Ended December 31, Shares of Common Stock 2019 2018 2017 Ordinary income (1) $ 0.939 49.95 % $ 1.474 83.73 % $ 1.356 70.87 % Qualified dividend 0.004 0.21 0.003 0.19 0.002 0.11 Return of capital 0.312 16.62 0.275 15.64 0.344 18.00 Capital gains (2) 0.600 31.93 0.008 0.44 — — Unrecaptured section 1250 gains 0.025 1.29 — — 0.211 11.02 $ 1.880 100.00 % $ 1.760 100.00 % $ 1.913 100.00 % _________________ (1) The Tax Cuts and Jobs Act enacted on December 22, 2017 generally allows a deduction for noncorporate taxpayers equal to 20% of ordinary dividends distributed by a REIT (excluding capital gain dividends and qualified dividend income). The amount of dividend eligible for this deduction is referred to as the Section 199A Dividend. For the year ended December 31, 2019 , the Section 199A Dividend is equal to the total ordinary income dividend. (2) Capital gains are comprised entirely of 20% rate gains.

Quarterly Financial Informati_3

Quarterly Financial Information of the Company (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Schedule of summarized quarterly financial data	Summarized quarterly financial data for the years ended December 31, 2019 and 2018 was as follows: 2019 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 201,202 $ 200,492 $ 215,525 $ 220,235 Net income 41,794 47,215 48,298 77,922 Net income attributable to Kilroy Realty Corporation 36,903 42,194 43,846 72,500 Net income available to common stockholders 36,903 42,194 43,846 72,500 Net income available to common stockholders per share – basic 0.36 0.41 0.41 0.68 Net income available to common stockholders per share – diluted 0.36 0.41 0.41 0.67 2018 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 182,822 $ 187,072 $ 186,562 $ 190,842 Net income 40,971 31,755 38,310 166,890 Net income attributable to Kilroy Realty Corporation 36,246 27,549 34,400 160,220 Net income available to common stockholders 36,246 27,549 34,400 160,220 Net income available to common stockholders per share – basic 0.36 0.27 0.34 1.59 Net income available to common stockholders per share – diluted 0.36 0.27 0.33 1.58 ____________________ (1) The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. For the year ended December 31, 2018 , the summation of the quarterly net income available to common stockholders per share does not equal the annual number reported on the consolidated statements of operations due to the Company’s at-the-market stock offering activity during the year.

Quarterly Financial Informati_4

Quarterly Financial Information of the Operating Partnership (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Schedule of summarized quarterly financial data	Summarized quarterly financial data for the years ended December 31, 2019 and 2018 was as follows: 2019 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 201,202 $ 200,492 $ 215,525 $ 220,235 Net income 41,794 47,215 48,298 77,922 Net income attributable to Kilroy Realty Corporation 36,903 42,194 43,846 72,500 Net income available to common stockholders 36,903 42,194 43,846 72,500 Net income available to common stockholders per share – basic 0.36 0.41 0.41 0.68 Net income available to common stockholders per share – diluted 0.36 0.41 0.41 0.67 2018 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per share amounts) Revenues $ 182,822 $ 187,072 $ 186,562 $ 190,842 Net income 40,971 31,755 38,310 166,890 Net income attributable to Kilroy Realty Corporation 36,246 27,549 34,400 160,220 Net income available to common stockholders 36,246 27,549 34,400 160,220 Net income available to common stockholders per share – basic 0.36 0.27 0.34 1.59 Net income available to common stockholders per share – diluted 0.36 0.27 0.33 1.58 ____________________ (1) The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. For the year ended December 31, 2018 , the summation of the quarterly net income available to common stockholders per share does not equal the annual number reported on the consolidated statements of operations due to the Company’s at-the-market stock offering activity during the year.
Kilroy Realty L.P. [Member]
Schedule of summarized quarterly financial data	Summarized quarterly financial data for the years ended December 31, 2019 and 2018 was as follows: 2019 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per unit amounts) Revenues $ 201,202 $ 200,492 $ 215,525 $ 220,235 Net income 41,794 47,215 48,298 77,922 Net income attributable to the Operating Partnership 37,508 42,901 44,589 73,740 Net income available to common unitholders 37,508 42,901 44,589 73,740 Net income available to common unitholders per unit – basic 0.36 0.41 0.41 0.68 Net income available to common unitholders per unit – diluted 0.36 0.41 0.41 0.67 2018 Quarter Ended (1) March 31, June 30, September 30, December 31, (in thousands, except per unit amounts) Revenues $ 182,822 $ 187,072 $ 186,562 $ 190,842 Net income 40,971 31,755 38,310 166,890 Net income attributable to the Operating Partnership 36,893 28,015 34,993 163,309 Net income available to common unitholders 36,893 28,015 34,993 163,309 Net income available to common unitholders per unit – basic 0.36 0.27 0.34 1.58 Net income available to common unitholders per unit – diluted 0.36 0.27 0.33 1.57 ___________________ (1) The summation of the quarterly financial data may not equal the annual number reported on the consolidated statements of operations due to rounding. For the year ended December 31, 2018

Organization and Ownership (Det

Organization and Ownership (Details) - Dec. 31, 2019	building	property	ft²	Total	project	residential_unit	tenant
Real Estate Properties [Line Items]
Rentable Square Feet			13,475,795
Stabilized office properties [Member]
Real Estate Properties [Line Items]
Number of buildings	112	4
Rentable Square Feet			13,475,795
Number of Tenants | tenant							451
Percentage Occupied				94.60%
Percentage Leased (unaudited)				97.00%
Stabilized residential properties [Member]
Real Estate Properties [Line Items]
Number of buildings | building	1
Percentage Occupied				82.40%
Number of Units | building	200
In-process development projects - tenant improvement [Member]
Real Estate Properties [Line Items]
Number of buildings | project					2
Rentable Square Feet			846,000
In-process development projects - under construction [Member]
Real Estate Properties [Line Items]
Number of buildings | project					6
Rentable Square Feet			2,291,000
Completed residential development project [Member]
Real Estate Properties [Line Items]
Number of buildings | project					1
Rentable Units | residential_unit						237
Retail site [Member] | In-process development projects - under construction [Member]
Real Estate Properties [Line Items]
Number of residential units | residential_unit						564

Organization and Ownership - Na

Organization and Ownership - Narrative (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019building	Dec. 31, 2019property	Dec. 31, 2019ft²	Dec. 31, 2019	Dec. 31, 2019a	Dec. 31, 2019property_partnership	Dec. 31, 2019project	Dec. 31, 2018
Real Estate Properties [Line Items]
Lease-up properties occupancy percentage	95.00%
Lease-up properties occupancy duration	1 year
Ownership interest of noncontrolling interest					1.90%				2.00%
Kilroy Realty Finance, Inc. [Member]
Real Estate Properties [Line Items]
Common general partnership interest in the Finance Partnership (percentage)		1.00%
101 First LLC and 303 Second LLC [Member]
Real Estate Properties [Line Items]
Ownership interest					56.00%
Redwood LLC [Member]
Real Estate Properties [Line Items]
Ownership interest					93.00%
Operating Partnership [Member]
Real Estate Properties [Line Items]
Ownership interest					98.10%				98.00%
Finance Partnership [Member] | Operating Partnership [Member]
Real Estate Properties [Line Items]
Ownership interest		99.00%
Washington [Member]
Real Estate Properties [Line Items]
Number of properties		1	8
Number of development projects | project								1
Development properties [Member]
Real Estate Properties [Line Items]
Number of properties							3	2
Area of undeveloped land | a						61
Development properties [Member] | 101 First LLC and 303 Second LLC [Member]
Real Estate Properties [Line Items]
Number of properties | property_partnership							2
Office properties [Member]
Real Estate Properties [Line Items]
Number of properties		112	4
Office properties [Member] | San Francisco, California [Member] | 101 First LLC and 303 Second LLC [Member]
Real Estate Properties [Line Items]
Number of properties			1
Office properties [Member] | Redwood City, California [Member] | Redwood LLC [Member]
Real Estate Properties [Line Items]
Number of properties			2
Development sites [Member]
Real Estate Properties [Line Items]
Number of properties | project								5
Properties and development projects [Member]
Real Estate Properties [Line Items]
Property ownership percentage		100.00%
Development Project in San Francisco [Member] | Development properties [Member] | San Francisco, California [Member]
Real Estate Properties [Line Items]
Number of properties			1
Development Project in San Francisco [Member] | Office properties [Member] | San Francisco, California [Member]
Real Estate Properties [Line Items]
Area of real estate property | ft²				394,340

Basis of Presentation and Sig_4

Basis of Presentation and Significant Accounting Policies - Allocation of Rental Income (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Basis of Presentation and Significant Accounting Policies [Abstract]
Fixed lease payments	$ 710,557
Variable lease payments	115,915
Total rental income	$ 826,472

Basis of Presentation and Sig_5

Basis of Presentation and Significant Accounting Policies - Narrative (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2019USD ($)variable_interest_entity	Dec. 31, 2019USD ($)segmentvariable_interest_entityproperty_partnership	Dec. 31, 2018USD ($)variable_interest_entityproperty_partnership	Dec. 31, 2017USD ($)	Dec. 31, 2019building	Dec. 31, 2019property	Dec. 31, 2019	Dec. 31, 2019property_partnership	Dec. 31, 2019project	Jan. 01, 2019USD ($)ground_lease
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of VIEs | variable_interest_entity		4	3
VIE asset amount	$ 676,700,000	$ 676,700,000	$ 615,400,000
VIE, carrying amount, liabilities	40,100,000	40,100,000	45,100,000
Noncontrolling interest in consolidated subsidiary	195,431,000	195,431,000	192,363,000
Lease income		826,472,000
Leasing costs		7,615,000
Number of ground leases | ground_lease										4
Weighted average discount rate							5.15%
Right of use ground lease asset (6)	96,348,000	96,348,000								$ 96,272,000
Ground lease liabilities	$ 98,400,000	$ 98,400,000								98,349,000
Number of consolidated property partnerships | property_partnership		3
Conversion ratio		1
Income tax provision		$ 0	0	$ 0
Number of operating segments | segment		1
Washington [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of buildings					1	8
Number of development projects | project									1
Building and building improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Depreciation of real estate		$ 211,900,000	198,600,000	$ 190,500,000
Kilroy Realty Finance, Inc. [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of general partnership interest owned by wholly-owned subsidiary of the Company		1.00%
Minimum [Member] | Building and building improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property depreciable lives		25 years
Minimum [Member] | Leasehold improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property depreciable lives		1 year
Maximum [Member] | Building and building improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property depreciable lives		40 years
Maximum [Member] | Leasehold improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property depreciable lives		20 years
Lease Agreements [Member] | Minimum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Finite-lived intangible asset, useful life		1 year
Lease Agreements [Member] | Maximum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Finite-lived intangible asset, useful life		20 years
Disposal group, disposed of by sale [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Restricted cash			$ 113,100,000
100 First LLC and 303 Second LLC [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of VIEs	2		2
Noncontrolling interest in consolidated subsidiary	$ 189,600,000	$ 189,600,000	$ 186,400,000
Real estate investment [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
VIE asset amount	$ 598,000,000	598,000,000	$ 543,900,000
Accounting Standards Update 2016-02 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Leasing costs		11,400,000
Cumulative adjustment										(3,146,000)
Right of use ground lease asset (6)										82,900,000
Ground lease liabilities										87,400,000
Accounting Standards Update 2016-02 [Member] | Accumulated Distributions in Excess of Net Income [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Cumulative adjustment										$ (3,146,000)
Property expense reimbursement [Member] | Accounting Standards Update 2016-02 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Lease income		$ 13,900,000
Development properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of buildings								3	2
Development properties [Member] | 100 First LLC and 303 Second LLC [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of buildings | property_partnership								2

Acquisitions - Operating Proper

Acquisitions - Operating Property Acquisitions (Details) $ in Millions	Oct. 15, 2019USD ($)ft²building	Dec. 21, 2018USD ($)ft²building	Jan. 31, 2018USD ($)ft²building	Dec. 31, 2019USD ($)ft²building	Dec. 31, 2018USD ($)ft²building
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Rentable Square Feet (unaudited) | ft²				13,475,795
Purchase price				$ 173	$ 308.2
Revenue contributed from acquired properties				3.7	8
Net income (loss) contributed from acquired properties				$ (0.1)	$ 1.7
3101-3243 La Cienega Boulevard, Culver City, CA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings | building	19			19
Rentable Square Feet (unaudited) | ft²	151,908
Occupancy percent				100.00%
Purchase price	$ 186
345, 347 & 349 Oyster Point Boulevard, South San Francisco, CA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings | building			3
Rentable Square Feet (unaudited) | ft²			145,530
Occupancy percent				100.00%
Purchase price			$ 111
345 Brannan Street, San Francisco, CA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings | building		1
Rentable Square Feet (unaudited) | ft²		110,050
Occupancy percent				99.70%
Purchase price		$ 146
345, 347 & 349 Oyster Point Boulevard, South San Francisco, CA and 345 Brannan Street, San Francisco, CA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings | building					4
Rentable Square Feet (unaudited) | ft²					255,580
Purchase price					$ 257

Acquisitions - Estimated Fair V

Acquisitions - Estimated Fair Values of Assets and Liabilities Assumed (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)acquisition
Assets
Land and improvements	$ 150,561	$ 80,269
Buildings and improvements	30,932	172,059
Deferred leasing costs and acquisition-related intangible assets	12,063	13,593
Right of use ground lease asset	13,334
Total assets acquired	206,890	265,921
Liabilities
Acquisition-related intangible liabilities	9,950	8,921
Ground lease liability	10,940
Total liabilities assumed	20,890	8,921
Net assets and liabilities acquired	$ 186,000	$ 257,000
Number of acquisitions | acquisition		2
Discount rate	4.79%
Below-market leases acquired	$ 10,000	$ 8,900
Weighted average amortization period of below-market leases	3 years 6 months	9 years 9 months 18 days
In-place leases [Member]
Assets
Deferred leasing costs and acquisition-related intangible assets	$ 9,200	$ 11,800
Liabilities
Weighted average amortization period of above-market leases in years	3 years 3 months 18 days	1 year 3 months 18 days
Deferred leasing costs [Member]
Assets
Deferred leasing costs and acquisition-related intangible assets	$ 2,900	$ 1,800
Liabilities
Weighted average amortization period of above-market leases in years	3 years 6 months	6 years 7 months 6 days

Acquisitions - Development Proj

Acquisitions - Development Project Acquisitions and Acquisition Costs (Details) $ in Thousands	Dec. 12, 2019USD ($)	Aug. 19, 2019USD ($)	Jun. 01, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)property	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Purchase price				$ 173,000	$ 308,200
Asset acquisition, accrued liabilities				20,890	8,921
Restricted cash				16,300	119,430	$ 9,149	$ 56,711
Payments to acquire land parcel				99,500
Acquisition costs, capitalized				1,600	$ 3,800	$ 4,600
1335 Broadway & 901 Park Boulevard, San Diego, CA [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Purchase price		$ 40,000
Asset acquisition, accrued liabilities		$ 4,000
Seattle CBD Project [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Purchase price	$ 133,000
Asset acquisition, accrued liabilities				6,300
Restricted cash				$ 10,000
Kilroy Oyster Point [Member]
Schedule of Asset Acquisitions, by Acquisition [Line Items]
Number of buildings | property					3
Purchase price			$ 308,200
Asset acquisition, accrued liabilities			$ 40,600

Dispositions - Operating Proper

Dispositions - Operating Property Dispositions (Details) $ in Thousands	1 Months Ended						12 Months Ended
	Oct. 31, 2019USD ($)ft²property	May 31, 2019USD ($)ft²property	Dec. 31, 2018USD ($)ft²property	Nov. 30, 2018USD ($)ft²property	Sep. 30, 2017USD ($)ft²aproperty	Jan. 31, 2017USD ($)ft²property	Dec. 31, 2019USD ($)ft²property	Dec. 31, 2018USD ($)ft²property	Dec. 31, 2017USD ($)ft²property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rentable square feet | ft²							13,475,795
Gains on sales of operating properties | $							$ 36,802	$ 142,926	$ 39,507
Disposal group, disposed of by sale [Member] | 2829 Townsgate Road, Thousand Oaks, CA and 2211 Michelson Drive, Irvine, CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property							2
Rentable square feet | ft²							355,654
Proceeds from sale of property held-for-sale | $							$ 133,800
Disposal group, disposed of by sale [Member] | 2829 Townsgate Road, Thousand Oaks, CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property		1
Rentable square feet | ft²		84,098
Proceeds from sale of property held-for-sale | $		$ 18,300
Disposal group, disposed of by sale [Member] | 2211 Michelson Drive Irvine CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property	1
Rentable square feet | ft²	271,556
Proceeds from sale of property held-for-sale | $	$ 115,500
Disposal group, disposed of by sale [Member] | 1310-1327 Chesapeake Terrace, Sunnyvale, CA , Plaza Yarrow Bay Properties, and 23925, 23975, & 24025 Park Sorrento, Calabasas, CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property			11					11
Rentable square feet | ft²			772,246					772,246
Proceeds from sale of property held-for-sale | $								$ 373,000
Disposal group, disposed of by sale [Member] | 1325-1327 Chesapeake Terrace, Sunnyvale, CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property				4
Rentable square feet | ft²				266,982
Proceeds from sale of property held-for-sale | $				$ 160,300
Disposal group, disposed of by sale [Member] | Plaza Yarrow Bay Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property				4
Rentable square feet | ft²				279,924
Proceeds from sale of property held-for-sale | $				$ 134,500
Disposal group, disposed of by sale [Member] | 23925, 23975, & 24025 Park Sorrento, Calabasas, CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property			3					3
Rentable square feet | ft²			225,340					225,340
Proceeds from sale of property held-for-sale | $			$ 78,200
Disposal group, disposed of by sale [Member] | 5717 Pacific Center Boulevard, San Diego, CA and Sorrento Mesa and Mission Valley Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property									11
Rentable square feet | ft²									743,138
Proceeds from sale of property held-for-sale | $									$ 186,600
Disposal group, disposed of by sale [Member] | 5717 Pacific Center Boulevard, San Diego, CA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property						1
Rentable square feet | ft²						67,995
Proceeds from sale of property held-for-sale | $						$ 12,100
Disposal group, disposed of by sale [Member] | Sorrento Mesa and Mission Valley Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings | property					10
Rentable square feet | ft²					675,143
Proceeds from sale of property held-for-sale | $					$ 174,500
Area of land | a					5

Dispositions - Land Disposition

Dispositions - Land Dispositions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on sales of land	$ 0	$ 11,825	$ 449
Disposal group, disposed of by sale [Member] | Plaza Yarrow Bay Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on sales of land		$ 11,800
Disposal group, disposed of by sale [Member] | Sorrento Mesa and Mission Valley Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain (loss) on sales of land			$ 400

Dispositions - Restricted Cash

Dispositions - Restricted Cash Related to Dispositions (Details) $ in Millions	Dec. 31, 2018USD ($)
Disposal group, disposed of by sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Restricted cash	$ 113.1

Deferred Leasing Costs and Ac_3

Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net - Deferred Leasing Costs and Acquisition-related Intangible Assets and Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Total deferred leasing costs and acquisition-related intangible assets, net	$ 212,805	$ 197,574
Acquisition-related Intangible Liabilities, Net [Abstract]
Total acquisitions-related intangible liabilities, net	24,092	29,138
Deferred leasing costs [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	286,026	266,905
Accumulated amortization	(100,145)	(100,805)
Finite-lived intangible assets	185,881	166,100
Above market leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	611	2,836
Accumulated amortization	(116)	(2,150)
Finite-lived intangible assets	495	686
In-place leases [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	58,076	66,526
Accumulated amortization	(31,647)	(36,174)
Finite-lived intangible assets	26,429	30,352
Below-market ground lease obligation, net [Member]
Deferred Leasing Costs and Acquisition-related Intangible Assets and Liabilities, Net
Finite-lived intangible assets/liabilities, gross	0	490
Accumulated amortization	0	(54)
Finite-lived intangible assets	0	436
Below-market operating leases [Member]
Acquisition-related Intangible Liabilities, Net [Abstract]
Acquisition-related intangible liabilities, gross	51,263	53,523
Accumulated amortization	(27,171)	(29,978)
Acquisition-related intangible liabilities, net	24,092	23,545
Above-market ground lease obligation [Member]
Acquisition-related Intangible Liabilities, Net [Abstract]
Acquisition-related intangible liabilities, gross	0	6,320
Accumulated amortization	0	(727)
Acquisition-related intangible liabilities, net	$ 0	$ 5,593

Deferred Leasing Costs and Ac_4

Deferred Leasing Costs and Acquisition-Related Intangible Assets and Liabilities, net - Amortization of Deferred Leasing Costs and Acquisition-related Intangibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	$ 45,188	$ 40,415	$ 41,704
Deferred leasing costs [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	35,779	34,341	31,675
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets, 2020	30,897
Finite-lived intangible assets, 2021	27,043
Finite-lived intangible assets, 2022	23,642
Finite-lived intangible assets, 2023	19,904
Finite-lived intangible assets, 2024	16,976
Finite-lived intangible assets, thereafter	67,419
Finite-lived intangible assets	185,881	166,100
Above market leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	192	444	2,240
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets, 2020	38
Finite-lived intangible assets, 2021	38
Finite-lived intangible assets, 2022	38
Finite-lived intangible assets, 2023	38
Finite-lived intangible assets, 2024	38
Finite-lived intangible assets, thereafter	305
Finite-lived intangible assets	495	686
In-place leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	18,615	15,915	18,650
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets, 2020	11,379
Finite-lived intangible assets, 2021	6,668
Finite-lived intangible assets, 2022	4,001
Finite-lived intangible assets, 2023	1,641
Finite-lived intangible assets, 2024	602
Finite-lived intangible assets, thereafter	2,138
Finite-lived intangible assets	26,429	30,352
Below-market ground lease obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization for the period related to deferred leasing costs and acquisition-related intangibles	0	8	8
Estimated annual amortization related to acquisition-related intangible assets
Finite-lived intangible assets	0	436
Below-market operating leases [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of intangible liabilities	(9,398)	(10,192)	(10,768)
Estimated annual amortization related to acquisition-related intangible liabilities
Acquisition-related intangible liabilities, 2020	(7,258)
Acquisition-related intangible liabilities, 2021	(4,543)
Acquisition-related intangible liabilities, 2022	(3,553)
Acquisition-related intangible liabilities, 2023	(1,866)
Acquisition-related intangible liabilities, 2024	(1,090)
Acquisition-related intangible liabilities, thereafter	(5,782)
Acquisition-related intangible liabilities	(24,092)	(23,545)
Above-market ground lease obligation [Member]
Amortization for the period related to deferred leasing costs and acquisition-related intangibles
Amortization of intangible liabilities	0	(101)	$ (101)
Estimated annual amortization related to acquisition-related intangible liabilities
Acquisition-related intangible liabilities	$ 0	$ (5,593)

Receivables - Current Receivabl

Receivables - Current Receivables and Deferred Rent Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current Receivables, net
Current receivables	$ 27,660	$ 24,815
Allowance for uncollectible tenant receivables	(1,171)	(4,639)
Current receivables, net	26,489	20,176
Deferred Rent Receivables, net
Deferred rent receivables	339,489	270,346
Allowance for deferred rent receivables	(1,552)	(3,339)
Deferred rent receivables, net	$ 337,937	$ 267,007

Prepaid Expenses and Other As_3

Prepaid Expenses and Other Assets, Net - Schedule of Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Furniture, fixtures and other long-lived assets, net	$ 35,286	$ 36,833
Notes receivable	1,651	2,113
Prepaid expenses	18,724	13,927
Total prepaid expenses and other assets, net	55,661	52,873
Non-refundable acquisition deposit	$ 3,600	$ 2,900

Secured and Unsecured Debt of_4

Secured and Unsecured Debt of the Company - Narrative (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Secured debt	$ 258,593,000	$ 335,531,000
Line of credit [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	150,000,000
Unsecured debt [Member]
Debt Instrument [Line Items]
Long-term debt	$ 3,300,000,000	$ 2,600,000,000

Secured and Unsecured Debt of_5

Secured and Unsecured Debt of the Operating Partnership - Secured Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Secured Debt
Secured debt	$ 258,593	$ 335,531
Kilroy Realty L.P. [Member]
Secured Debt
Long-term debt, gross	3,579,502
Secured debt	258,593	335,531
Unamortized Deferred Financing Costs	(20,300)
Kilroy Realty L.P. [Member] | Secured debt [Member]
Secured Debt
Secured debt	259,502	336,570
Unamortized Deferred Financing Costs	(909)	(1,039)
Long-term debt	258,593	335,531
Net book value of properties pledged as collateral for secured debt	$ 251,200
Kilroy Realty L.P. [Member] | Secured debt [Member] | 3.57% Mortgage Payable due December 2026 [Member]
Secured Debt
Stated interest rate	3.57%
Effective interest rate	3.57%
Long-term debt, gross	$ 170,000	170,000
Kilroy Realty L.P. [Member] | Secured debt [Member] | 4.48% Mortgage Payable due July 2027 [Member]
Secured Debt
Stated interest rate	4.48%
Effective interest rate	4.48%
Long-term debt, gross	$ 89,502	91,332
Kilroy Realty L.P. [Member] | Secured debt [Member] | 6.05% Mortgage Payable Due June 1, 2019 [Member]
Secured Debt
Stated interest rate	6.05%
Effective interest rate	3.50%
Long-term debt, gross	$ 0	$ 75,238

Secured and Unsecured Debt of_6

Secured and Unsecured Debt of the Operating Partnership - Unsecured Senior Notes Table (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Nov. 30, 2018
Debt Instrument [Line Items]
Unsecured debt, net	$ 3,049,185		$ 2,552,070
Unsecured debt [Member]
Debt Instrument [Line Items]
Unamortized discount (premium), net	6,500		6,600
Unamortized debt issuance expense	18,700		15,400
Kilroy Realty L.P. [Member]
Debt Instrument [Line Items]
Unamortized debt issuance expense	20,300
Long-term debt, gross	3,579,502
Unsecured debt, net	3,049,185		2,552,070
Kilroy Realty L.P. [Member] | Unsecured debt [Member]
Debt Instrument [Line Items]
Unsecured debt, net	$ 2,899,839		2,402,979
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 3.050% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	3.05%	3.05%
Effective interest rate	3.064%
Long-term debt, gross	$ 500,000		0
Unamortized discount and deferred financing costs	(5,998)		0
Unsecured debt, net	$ 494,002		$ 0
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.750% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate			4.75%	4.75%
Effective interest rate	4.80%
Long-term debt, gross	$ 400,000		$ 400,000
Unamortized discount and deferred financing costs	(4,446)		(4,960)
Unsecured debt, net	$ 395,554		395,040
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.350% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	4.35%
Effective interest rate	4.35%
Long-term debt, gross	$ 200,000		200,000
Unamortized discount and deferred financing costs	(1,186)		(1,375)
Unsecured debt, net	$ 198,814		198,625
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.300% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	4.30%
Effective interest rate	4.30%
Long-term debt, gross	$ 50,000		50,000
Unamortized discount and deferred financing costs	(290)		(342)
Unsecured debt, net	$ 49,710		49,658
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 3.450% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	3.45%
Effective interest rate	3.47%
Long-term debt, gross	$ 425,000		425,000
Unamortized discount and deferred financing costs	(2,907)		(3,493)
Unsecured debt, net	$ 422,093		421,507
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 3.450% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	3.45%
Effective interest rate	3.45%
Long-term debt, gross	$ 75,000		75,000
Unamortized discount and deferred financing costs	(390)		(432)
Unsecured debt, net	$ 74,610		74,568
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 3.350% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	3.35%
Effective interest rate	3.35%
Long-term debt, gross	$ 175,000		175,000
Unamortized discount and deferred financing costs	(825)		(941)
Unsecured debt, net	$ 174,175		174,059
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.375% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	4.375%
Effective interest rate	4.444%
Long-term debt, gross	$ 400,000		400,000
Unamortized discount and deferred financing costs	(3,185)		(3,738)
Unsecured debt, net	$ 396,815		396,262
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.250% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	4.25%
Effective interest rate	4.35%
Long-term debt, gross	$ 400,000		400,000
Unamortized discount and deferred financing costs	(5,100)		(5,632)
Unsecured debt, net	$ 394,900		394,368
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 3.800% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	3.80%
Effective interest rate	3.80%
Long-term debt, gross	$ 300,000		300,000
Unamortized discount and deferred financing costs	(834)		(1,108)
Unsecured debt, net	$ 299,166		$ 298,892

Secured and Unsecured Debt of_7

Secured and Unsecured Debt of the Operating Partnership - Unsecured Senior Notes - Registered Offerings and Private Placement (Details) - USD ($)	1 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Nov. 30, 2018
Debt Instrument [Line Items]
Debt issuance discount		$ (6,500,000)
Loss on early extinguishment of debt (Note 9)		0	$ 12,623,000	$ 5,312,000
Unsecured debt [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,600,000,000	3,300,000,000	2,600,000,000
Kilroy Realty L.P. [Member]
Debt Instrument [Line Items]
Loss on early extinguishment of debt (Note 9)		$ 0	12,623,000	$ 5,312,000
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 3.050% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount					$ 500,000,000	$ 400,000,000
Debt issuance discount					$ (600,000)
Stated interest rate		3.05%			3.05%
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.750% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 400,000,000		$ 400,000,000
Debt issuance discount						$ (1,500,000)
Stated interest rate	4.75%		4.75%			4.75%
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 6.625% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount	$ 250,000,000		$ 250,000,000
Stated interest rate	6.625%		6.625%
Loss on early extinguishment of debt (Note 9)	$ 12,600,000
Extinguishment of debt	11,800,000
Write off of unamortized discount and deferred financing costs	$ 800,000
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.300% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount		$ 50,000,000
Stated interest rate		4.30%
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | 4.350% Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount		$ 200,000,000
Stated interest rate		4.35%
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | Series A Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount		$ 50,000,000
Long-term debt		50,000,000
Kilroy Realty L.P. [Member] | Unsecured debt [Member] | Series B Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Principal amount		200,000,000
Long-term debt		$ 200,000,000
Kilroy Realty L.P. [Member] | Private placement [Member] | Unsecured debt [Member] | Series A and B Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Operating partnership, payment percent		5.00%
Operating partnership, total payment percentage		100.00%

Secured and Unsecured Debt of_8

Secured and Unsecured Debt of the Operating Partnership - Unsecured Revolving Credit Facility and Term Loan Facility (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Terms of the Credit Facility
Outstanding borrowings		$ 245,000,000	$ 45,000,000
Borrowings on unsecured debt		0	120,000,000	$ 0
Line of credit [Member]
Terms of the Credit Facility
Total borrowing capacity		150,000,000
Kilroy Realty L.P. [Member]
Terms of the Credit Facility
Outstanding borrowings		245,000,000	45,000,000
Unamortized debt issuance expense		20,300,000
Borrowings on unsecured debt		0	120,000,000	$ 0
Kilroy Realty L.P. [Member] | Revolving credit facility [Member]
Terms of the Credit Facility
Outstanding borrowings		245,000,000	45,000,000
Remaining borrowing capacity		505,000,000	705,000,000
Total borrowing capacity		$ 750,000,000	$ 750,000,000
Interest rate		2.76%	3.48%
Facility fee-annual rate		0.20%	0.20%
Contingent additional borrowings		$ 600,000,000
Unamortized debt issuance expense		3,400,000	$ 4,700,000
Kilroy Realty L.P. [Member] | Line of credit [Member]
Terms of the Credit Facility
Total borrowing capacity		150,000,000	150,000,000
Kilroy Realty L.P. [Member] | $150.0 million term loan facility [Member] | Line of credit [Member]
Terms of the Credit Facility
Outstanding borrowings	$ 150,000,000	150,000,000	150,000,000
Remaining borrowing capacity		$ 0	$ 0
Interest rate		2.85%	3.49%
Undrawn facility fee-annual rate		0.20%	0.20%
Unamortized debt issuance expense		$ 700,000	$ 900,000
Line of credit facility, increase (decrease)	(30,000,000)
Borrowings on unsecured debt	$ 120,000,000
Kilroy Realty L.P. [Member] | London Interbank Offered Rate (LIBOR) [Member] | Revolving credit facility [Member]
Terms of the Credit Facility
Basis spread on LIBOR		1.00%	1.00%
Kilroy Realty L.P. [Member] | London Interbank Offered Rate (LIBOR) [Member] | $150.0 million term loan facility [Member] | Line of credit [Member]
Terms of the Credit Facility
Basis spread on LIBOR		1.10%	1.10%

Secured and Unsecured Debt of_9

Secured and Unsecured Debt of the Operating Partnership - Debt Maturities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Stated debt maturities and scheduled amortization payments, excluding debt discounts
Debt issuance discount	$ (6,500)
Kilroy Realty L.P. [Member]
Stated debt maturities and scheduled amortization payments, excluding debt discounts
2020	5,137
2021	5,342
2022	400,554
2023	305,775
2024	431,006
Thereafter	2,431,688
Total aggregate principal value	3,579,502
Unamortized debt issuance expense	$ (20,300)

Secured and Unsecured Debt o_10

Secured and Unsecured Debt of the Operating Partnership - Capitalized Interest and Loan Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Interest expense	$ 48,537	$ 49,721	$ 66,040
Kilroy Realty L.P. [Member]
Debt Instrument [Line Items]
Gross interest expense	129,778	117,789	112,577
Capitalized interest and deferred financing costs	(81,241)	(68,068)	(46,537)
Interest expense	$ 48,537	$ 49,721	$ 66,040

Deferred Revenue and Acquisit_3

Deferred Revenue and Acquisition-Related Intangible Liabilities, net - Deferred Revenue and Acquisition-Related Intangible Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Deferred revenue	$ 96,271	$ 104,558
Other deferred revenue	19,125	15,950
Acquisition-related intangible liabilities, net	24,092	29,138
Deferred revenue and acquisition-related intangible liabilities, net	$ 139,488	$ 149,646

Deferred Revenue and Acquisit_4

Deferred Revenue and Acquisition-Related Intangible Liabilities, net - Estimated Amortization of Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Revenue, Future Amortization Recognized By Year [Abstract]
Total	$ 96,271	$ 104,558
Tenant funded tenant improvements [Member]
Deferred Revenue Arrangement [Line Items]
Deferred revenues amortized and recognized as rental income	19,200	$ 18,400	$ 16,800
Deferred Revenue, Future Amortization Recognized By Year [Abstract]
2020	16,935
2021	15,426
2022	14,320
2023	12,553
2024	10,318
Thereafter	26,719
Total	$ 96,271

Noncontrolling Interests on t_3

Noncontrolling Interests on the Company’s Consolidated Financial Statements - Narrative (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)d$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Noncontrolling Interest [Line Items]
Ownership interest of noncontrolling interest	1.90%	2.00%
Conversion ratio	1
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Trading days | d	10
Aggregate value upon redemption of outstanding noncontrolling common units	$ 167,700	$ 126,400
Noncontrolling interest in consolidated subsidiary	195,431	192,363
100 First LLC & 303 Second LLC [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest in consolidated subsidiary		186,400
Redwood LLC [Member]
Noncontrolling Interest [Line Items]
Noncontrolling interest in consolidated subsidiary	$ 5,800	$ 6,000
Common units [Member] | Kilroy Realty L.P. [Member]
Noncontrolling Interest [Line Items]
Common units outstanding held by common limited partners (in units) | shares	2,023,287	2,025,287
Exchange of common units of the Operating Partnership (in units) | shares	2,000
Conversion ratio	1
Operating Partnership [Member]
Noncontrolling Interest [Line Items]
Ownership interest	98.10%	98.00%
101 First LLC and 303 Second LLC [Member]
Noncontrolling Interest [Line Items]
Ownership interest	56.00%
Noncontrolling interest in consolidated subsidiary	$ 189,600	$ 186,400

Noncontrolling Interests on t_4

Noncontrolling Interests on the Operating Partnership’s Consolidated Financial Statements - Narrative (Details)	Dec. 31, 2019	Dec. 31, 2018	Aug. 30, 2016
Noncontrolling Interest [Line Items]
Ownership interest of noncontrolling interest	1.90%	2.00%
Consolidated property partnerships [Member] | Norges Bank Real Estate Management (NBREM) [Member]
Noncontrolling Interest [Line Items]
Ownership interest of noncontrolling interest			44.00%

Stockholders' Equity of the C_3

Stockholders' Equity of the Company - Narrative (Details) - USD ($)	Aug. 15, 2017	Mar. 30, 2017	Jul. 31, 2019	Aug. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2018
Class of Stock [Line Items]
Common stock, value, issued					$ 1,060,000	$ 1,007,000
Aggregate net proceeds after selling commissions					$ 353,722,000	$ 130,693,000	$ 326,058,000
Sale of stock, shares issued (in shares)					106,016,287	100,746,988
Stock repurchase program, number of shares authorized to be repurchased					4,935,826
Original issuance costs					$ 0	$ 0	7,589,000
2014 At-The-Market Program [Member]
Class of Stock [Line Items]
Aggregate gross proceeds						$ 300,000,000
2018 At-The-Market Program [Member]
Class of Stock [Line Items]
Aggregate gross proceeds								$ 500,000,000
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock (in shares)	4,000,000	4,000,000
Preferred stock, dividend rate	6.375%
Preferred stock, liquidation preference per share (in dollars per share)	$ 25
Preferred stock liquidation preference	$ 100,000,000
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock (in shares)		4,000,000
Preferred stock, dividend rate		6.875%
Preferred stock, liquidation preference per share (in dollars per share)		$ 25
Preferred stock liquidation preference		$ 100,000,000
Series G And H Preferred Stock [Member]
Class of Stock [Line Items]
Original issuance costs							$ 7,600,000
Forward Equity Offering [Member]
Class of Stock [Line Items]
Common stock, value, issued				$ 360,500,000
Stock issued, price per share (in dollar per share)				$ 72.10
Aggregate net proceeds after selling commissions			$ 354,300,000
Forward Equity Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Stock issued (in shares)			5,000,000	5,000,000
Aggregate net proceeds after selling commissions			$ 354,300,000
Sale of stock, shares issued (in shares)			5,000,000
Forward Equity Offering [Member] | Common Stock [Member] | 2014 At-The-Market Program [Member]
Class of Stock [Line Items]
Sale of stock, shares available for sale (in shares)						1,369,729
Forward Equity Offering [Member] | Common Stock [Member] | 2018 At-The-Market Program [Member]
Class of Stock [Line Items]
Stock issued, price per share (in dollar per share)					$ 80.08
Sale of stock, shares available for sale (in shares)					3,147,110
Sale of stock, shares issued (in shares)					447,466	447,466
Sale of stock, available for sale under program					$ 214,200,000

Stockholders' Equity of the C_4

Stockholders' Equity of the Company - At-The-Market Offering and Derivatives and Distributions (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Dividends Payable [Line Items]
Aggregate net proceeds after selling commissions	$ 353,722	$ 130,693	$ 326,058
Accrued dividend and distributions
Accrued dividends and distributions	$ 53,219	$ 47,559
Summary of shares and units
Common stock	106,016,287	100,746,988
Restricted Stock Units (RSUs) [Member]
Summary of shares and units
RSUs	1,651,905	1,711,628
Common stockholders and noncontrolling unitholders [Member]
Accrued dividend and distributions
Accrued dividends and distributions	$ 53,219	$ 47,559
Common Stock [Member]
Accrued dividend and distributions
Accrued dividends and distributions	$ 51,418	$ 45,840
Summary of shares and units
Common stock	106,016,287	100,746,988
Common units [Member]
Accrued dividend and distributions
Accrued dividends and distributions	$ 981	$ 922
Issuance of Equity under ATM Program [Member]
Dividends Payable [Line Items]
Shares of common stock sold during the period (in shares)		1,817,195	235,077
Weighted average price per share of common stock (in dollars per share)		$ 73.64	$ 75.40
Aggregate gross proceeds		$ 133,800	$ 17,700
Aggregate net proceeds after selling commissions		132,100	17,500
Kilroy Realty L.P. [Member]
Dividends Payable [Line Items]
Aggregate net proceeds after selling commissions	353,722	130,693	$ 326,058
Accrued dividend and distributions
Accrued dividends and distributions	53,219	47,559
Kilroy Realty L.P. [Member] | Restricted Stock Units (RSUs) [Member]
Accrued dividend and distributions
Accrued dividends and distributions	$ 820	$ 797
Kilroy Realty L.P. [Member] | Market measure-based Restricted Stock Units (RSUs) [Member]
Summary of shares and units
Number of RSUs outstanding (in shares)	932,675	1,018,337
Kilroy Realty L.P. [Member] | Common units [Member]
Summary of shares and units
Noncontrolling common units (in units)	2,023,287	2,025,287

Partners' Capital of the Oper_3

Partners' Capital of the Operating Partnership - Narrative (Details) - USD ($) $ in Thousands	Aug. 15, 2017	Mar. 30, 2017	Jul. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Common stock, shares issued (in shares)				106,016,287	100,746,988
Aggregate net proceeds after selling commissions				$ 353,722	$ 130,693	$ 326,058
Original issuance costs of redeemed preferred stock and preferred units (Note 13)				$ 0	$ 0	(7,589)
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock (in shares)	4,000,000	4,000,000
Preferred stock, dividend rate	6.375%
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock (in shares)		4,000,000
Preferred stock, dividend rate		6.875%
Series G And H Preferred Stock [Member]
Class of Stock [Line Items]
Original issuance costs of redeemed preferred stock and preferred units (Note 13)						$ (7,600)
Forward Equity Sale [Member]
Class of Stock [Line Items]
Aggregate net proceeds after selling commissions			$ 354,300
Forward Equity Sale [Member] | Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued (in shares)			5,000,000
Aggregate net proceeds after selling commissions			$ 354,300
Common units (in units)			5,000,000

Partners' Capital of the Oper_4

Partners' Capital of the Operating Partnership - At-The-Market Stock Offering, Common Units and Accrued Distributions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Aggregate net proceeds after selling commissions	$ 353,722	$ 130,693	$ 326,058
Summary of units
Ownership interest of noncontrolling interest	1.90%	2.00%
Accrued distributions
Accrued dividends and distributions	$ 53,219	$ 47,559
Common units [Member]
Accrued distributions
Accrued dividends and distributions	981	$ 922
Issuance of Equity under ATM Program [Member]
Class of Stock [Line Items]
Shares of common stock contributed by the Company (in shares)		1,817,195	235,077
Common units exchanged for shares of common stock by the Company (in units)		1,817,195	235,077
Aggregate gross proceeds		$ 133,800	$ 17,700
Aggregate net proceeds after selling commissions		132,100	17,500
Kilroy Realty L.P. [Member]
Class of Stock [Line Items]
Aggregate net proceeds after selling commissions	353,722	130,693	$ 326,058
Accrued distributions
Accrued dividends and distributions	53,219	47,559
Kilroy Realty L.P. [Member] | Restricted Stock Units (RSUs) [Member]
Accrued distributions
Accrued dividends and distributions	$ 820	$ 797
RSUs (in shares)	1,651,905	1,711,628
Kilroy Realty L.P. [Member] | Market measure-based Restricted Stock Units (RSUs) [Member]
Accrued distributions
Number of RSUs outstanding (in shares)	932,675	1,018,337
Kilroy Realty L.P. [Member] | Partners Capital Common Unit [Member]
Accrued distributions
Accrued dividends and distributions	$ 53,219	$ 47,559
Kilroy Realty L.P. [Member] | Partners capital general partner [Member]
Accrued distributions
Accrued dividends and distributions	51,418	45,840
Kilroy Realty L.P. [Member] | Partners capital limited partner [Member]
Accrued distributions
Accrued dividends and distributions	$ 981	$ 922
Kilroy Realty L.P. [Member] | Common units [Member]
Summary of units
Company owned common units in the Operating Partnership (in units)	106,016,287	100,746,988
Noncontrolling common units (in units)	2,023,287	2,025,287
Operating Partnership [Member]
Summary of units
Company owned general partnership interest	98.10%	98.00%

Share-Based and Other Compens_3

Share-Based and Other Compensation - Stockholder Approved Share-Based Incentive Compensation Plan (Details) shares in Millions	Dec. 31, 2019shares
Kilroy Realty 2006 Incentive Award Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	0.4
Shareholder Meeting Date May 21, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares requested	9.2

Share-Based and Other Compens_4

Share-Based and Other Compensation - 2019, 2018 and 2017 Share-Based Compensation Grants (Details) - shares	Feb. 01, 2019	Dec. 27, 2018	Feb. 14, 2018	Feb. 24, 2017	Feb. 28, 2019	Dec. 31, 2018	Feb. 28, 2017	Feb. 28, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock Units (RSUs) [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		161,290					229,976	282,038
Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		483,871
Market measure-based Restricted Stock Units (RSUs) [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	143,396	80,647	158,205	130,956	143,396
Market measure-based Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		266,130			288,378
Time-Based Restricted Stock Units (RSUs) [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		80,643					99,020	123,833		14,999	43,081
Time-Based Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		217,741			144,982
Forfeited in period (in shares)									10,733
2019 Performance-Based RSUs [Member] | Chief Executive Officer [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Forfeited in period (in shares)									24,353
December 2018 Market-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)						346,777
December 2018 Market-Based RSUs [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)							130,956	158,205
Time-Based Restricted Stock Units (RSUs), 2018 Special Time-Based RSU Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		298,384
Time-Based Restricted Stock Units (RSUs), 2018 Special Time-Based RSU Grant [Member] | Chief Executive Officer [Member] | Executive officer share-based compensation programs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Forfeited in period (in shares)									98,844

Share-Based and Other Compens_5

Share-Based and Other Compensation - 2018 Special Market-Based RSU Grant (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 27, 2018	Dec. 31, 2018	Dec. 31, 2018
December 2018 Market-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)		346,777
Award vesting period		3 years
Vesting criteria, one		75.00%	75.00%
Vesting criteria, two		25.00%	25.00%
Fair value RSUs granted	$ 23.8
Fair value per share on valuation date (in dollars per share)	$ 68.66		$ 68.66
Expected share price volatility (in dollars per share)	23.00%
Risk-free interest rate	2.40%
December 2018 Market-Based RSUs, TSR [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
Minimum [Member] | December 2018 Market-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target percent		0.00%
Maximum [Member] | December 2018 Market-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target percent		200.00%

Share-Based and Other Compens_6

Share-Based and Other Compensation - 2019, 2018 and 2017 Annual Performance-Based RSU Grants (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 01, 2019	Dec. 27, 2018	Feb. 14, 2018	Feb. 24, 2017	Feb. 28, 2019	Dec. 31, 2019
2019 Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						3 years
Vesting criteria, one						100.00%
Vesting criteria, two						50.00%
Vesting criteria, three						50.00%
Performance-based RSUs achievement target, participant one, percent						175.00%
Performance-based RSUs achievement target, all other participants, percent						150.00%
Fair value RSUs granted	$ 10.2		$ 10.8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Fair value per share on valuation date (in dollars per share)	$ 72.57		$ 70.08
2018 Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						3 years
Vesting criteria, two						50.00%
Vesting criteria, three						50.00%
Performance-based RSUs achievement target, participant one, percent						175.00%
Performance-based RSUs achievement target, all other participants, percent						150.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Expected share price volatility (in dollars per share)	19.00%		20.00%
Risk-free interest rate	2.48%		2.37%
2017 Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						3 years
Vesting criteria, one						100.00%
Vesting criteria, two						30.00%
Vesting criteria, three						40.00%
Performance-based RSUs achievement target, percent						131.00%
Fair value RSUs granted				$ 10.3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Fair value per share on valuation date (in dollars per share)				$ 80.89
Expected share price volatility (in dollars per share)				21.00%
Risk-free interest rate				1.39%
Market measure-based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Fair value per share on valuation date (in dollars per share)						$ 71.12
Executive officer share-based compensation programs [Member] | Market measure-based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	143,396	80,647	158,205	130,956	143,396
Market measure-based RSU estimate of probable [Member] | 2019 Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated RSUs earned based on FFO						229,095
Target level of achievement, one						125.00%
Target level of achievement, two						117.00%
Market measure-based RSU estimate of probable [Member] | 2018 Performance-Based RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated RSUs earned based on FFO						262,242
Market measure-based RSU estimate of probable [Member] | Market measure-based Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Estimated RSUs earned based on FFO	229,095		262,242	142,581		142,581

Share-Based and Other Compens_7

Share-Based and Other Compensation - Annual 2019, 2018 and 2017 and December 2018 Time-Based RSU Grants (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 01, 2019	Dec. 27, 2018	Feb. 14, 2018	Jan. 29, 2018	Feb. 24, 2017	Feb. 03, 2017	Feb. 28, 2017	Feb. 28, 2018	Dec. 31, 2019
December 2018 Time-Based RSU Grant [Member] [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting criteria, one									50.00%
Vesting criteria, two									50.00%
Time-Based Restricted Stock Units (RSUs), 2019 Time-Based RSU Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value RSUs granted	$ 10.1
Fair value per share (in dollars per share)	$ 69.89
Time-Based Restricted Stock Units (RSUs), 2018 Special Time-Based RSU Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value RSUs granted		$ 18.5
Fair value per share (in dollars per share)		$ 62
Time-Based Restricted Stock Units (RSUs), 2018 Time-Based RSU Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value RSUs granted								$ 8.4
Fair value per share (in dollars per share)			$ 66.46	$ 70.37				$ 70.37
RSUs granted (in units)			67,818	56,015
Time-Based Restricted Stock Units (RSUs), 2017 Time-Based RSU Grant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value RSUs granted							$ 7.5
Fair value per share (in dollars per share)					$ 77.16	$ 73.30
RSUs granted (in units)					57,901	41,119

Share-Based and Other Compens_8

Share-Based and Other Compensation - Summary of Market-Measure Based RSUs (Details) - Market measure-based Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Vested (in shares)	(265,737)	(265,918)	(194,991)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
RSU weighted average fair value, beginning balance (in dollars per share)	$ 67.29
Fair value per share on valuation date (in dollars per share)	71.12
Weighted average grant date fair value, vested (in dollars per share)	57.08
Weighted average fair value, issuance of dividend equivalents (in dollars per share)	74.11
Weighted average fair value, forfeited (in dollars per share)	70.07
RSU weighted average fair value, ending balance (in dollars per share)	$ 71.04	$ 67.29
Nonvested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of RSUs outstanding, beginning balance (in shares)	1,018,337
Granted (in shares)	231,191	601,012	170,994
Vested (in shares)	(261,990)
Issuance of dividend equivalents (in shares)	23,254
Forfeited (in shares)	(78,117)
Number of RSUs outstanding, ending balance (in shares)	932,675	1,018,337
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Fair value per share on valuation date (in dollars per share)	$ 71.12	$ 68.51	$ 78.97
Vested Restricted Stock Units R S U [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Vested RSUs, beginning balance (in shares)	35,761
Granted (in shares)	1,155
Vested (in shares)	(261,990)
Settled (in shares)	(264,814)
Issuance of dividend equivalents (in shares)	2,592
Forfeited (in shares)	(5)
Vested RSUs, ending balance (in shares)	36,679	35,761
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Total RSUs, beginning balance (in shares)	1,054,098
Granted (in shares)	232,346
Vested (in shares)	0
Settled (in shares)	(264,814)
Issuance of dividend equivalents (in shares)	25,846
Forfeited (in shares)	(78,122)
Total RSUs, ending balance (in shares)	969,354	1,054,098
Kilroy Realty 2006 Incentive Award Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Settled (in shares)	(125,220)

Share-Based and Other Compens_9

Share-Based and Other Compensation - Market-Measure Based RSUs (Details) - Market measure-based Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value per share on valuation date (in dollars per share)	$ 71.12
Vested (in shares)	(265,737)	(265,918)	(194,991)
Nonvested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	231,191	601,012	170,994
Fair value per share on valuation date (in dollars per share)	$ 71.12	$ 68.51	$ 78.97
Vested (in shares)	(261,990)
Vested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	1,155
Vested (in shares)	(261,990)
Total Fair Value at Vest Date	$ 18,703	$ 18,906	$ 14,270

Share-Based and Other Compen_10

Share-Based and Other Compensation - Summary of Time-Based RSUs (Details) - Time-Based Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Vested (in shares)	182,219	214,131	228,095
Nonvested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of RSUs outstanding, beginning balance (in shares)	586,779
Granted (in shares)	153,005	437,216	142,101
Vested (in shares)	153,464
Issuance of dividend equivalents (in shares)	13,341
Forfeited (in shares)	(55,813)
Number of RSUs outstanding, ending balance (in shares)	543,848	586,779
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
RSU weighted average fair value, beginning balance (in dollars per share)	$ 65.87
Fair value per share on valuation date (in dollars per share)	70.31	$ 64.21	$ 74.91
Weighted average grant date fair value, vested (in dollars per share)	67.26
Weighted average fair value, issuance of dividend equivalents (in dollars per share)	74.72
Weighted average fair value, forfeited (in dollars per share)	68.71
RSU weighted average fair value, ending balance (in dollars per share)	$ 66.66	$ 65.87
Vested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Vested RSUs, beginning balance (in shares)	1,089,088
Granted (in shares)	0
Vested (in shares)	153,464
Settled (in shares)	(198,183)
Issuance of dividend equivalents (in shares)	28,755
Forfeited (in shares)	0
Canceled (in shares)	(1,746)
Vested RSUs, ending balance (in shares)	1,071,378	1,089,088
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Total RSUs, beginning balance (in shares)	1,675,867
Granted (in shares)	153,005
Vested (in shares)	0
Settled (in shares)	(198,183)
Issuance of dividend equivalents (in shares)	42,096
Forfeited (in shares)	(55,813)
Canceled (in shares)	(1,746)
Total RSUs, ending balance (in shares)	1,615,226	1,675,867
Kilroy Realty 2006 Incentive Award Plan [Member] | Vested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Settled (in shares)	(82,646)

Share-Based and Other Compen_11

Share-Based and Other Compensation - Time-Based RSUs (Details) - Time-Based Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested (in shares)	(182,219)	(214,131)	(228,095)
Nonvested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	153,005	437,216	142,101
Fair value per share on valuation date (in dollars per share)	$ 70.31	$ 64.21	$ 74.91
Vested (in shares)	(153,464)
Vested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0
Vested (in shares)	(153,464)
Total Fair Value at Vest Date	$ 12,277	$ 14,768	$ 16,735

Share-Based and Other Compen_12

Share-Based and Other Compensation - Time-Based Restricted Stock Unit Activity (Details) - Time-Based Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested (in shares)	(182,219)	(214,131)	(228,095)
Nonvested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	153,005	437,216	142,101
Fair value per share on valuation date (in dollars per share)	$ 70.31	$ 64.21	$ 74.91
Vested (in shares)	(153,464)
Vested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0
Vested (in shares)	(153,464)
Total Fair Value at Vest Date	$ 12,277	$ 14,768	$ 16,735

Share-Based and Other Compen_13

Share-Based and Other Compensation - Nonvested Restricted Stock (Details) - Restricted Stock [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Nonvested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	0
Fair value per share on valuation date (in dollars per share)	$ 0	$ 0
Vested Restricted Stock Units RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested (in shares)	(22,884)	(24,261)
Total Fair Value at Vest Date	$ 1,652	$ 1,781

Share-Based and Other Compen_14

Share-Based and Other Compensation - Share-Based Compensation Cost Recorded During the Period and Other Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 27, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 32.8	$ 35.9	$ 26.3
Share-based compensation costs	5.8	8	$ 7.3
Unrecognized compensation costs	$ 50.5
Cost not yet recognized, period for recognition	2 years 1 month 6 days
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash retirement benefit, scenario one				$ 13.2
Cash retirement benefit, scenario two				$ 16.2
Compensation expense	$ 1.5	$ 12.1

Employee Benefit Plans - Narrat

Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2007
Retirement Benefits [Abstract]
Eligibility period for 401K savings plan, period	3 months
401(k) plan, maximum participant deferral percent	60.00%
401(k) plan, employer match per dollar of participant contribution	$ 0.50
401(k) plan, maximum employer match percentage	10.00%
401(k) plan, contributions made	$ 1,600,000	$ 1,500,000	$ 1,300,000
Deferred Compensation, maximum participant deferral percent				70.00%
Deferred Compensation, maximum director fees and bonuses that may be deferred (percent)				100.00%
Deferred Compensation, mandatory Company contributions as percentage of gross monthly salary (percent)				10.00%
Deferred Compensation, liability under Plan	$ 27,000,000	$ 21,700,000

Future Minimum Rent - Future Co

Future Minimum Rent - Future Contractual Minimum Rent (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Future contractual minimum rent under operating lease
2020	$ 675,636
2021	728,736
2022	785,239
2023	769,294
2024	727,399
Thereafter	4,054,487
Total	$ 7,740,791
Future contractual minimum rent under operating lease
2019		$ 566,783
2020		632,875
2021		631,835
2022		620,684
2023		586,371
Thereafter		3,240,143
Total		$ 6,278,691

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)ground_lease	Dec. 31, 2018USD ($)
Long-term Purchase Commitment [Line Items]
Commitments for contracts and executed leases, operating and redevelopment and development properties	$ 1,000
Weighted average remaining lease term	55 years
Variable lease, cost	$ 2.9
Period after which ground lease rentals are adjusted based on fair market value and the Consumer Price Index	5 years	5 years
Annual ground lease rental obligations limit	$ 1	$ 1
Duration of ground lease prior to increase five years	5 years
Average annual percentage rent for previous five years (percent)	50.00%
Duration of ground lease prior to increase ten years	10 years
Average annual percentage rent for previous ten years (percent)	60.00%	60.00%
Ground lease fixed ground rent increase, percent	5.00%
Ten year ground lease extension option [Member]
Long-term Purchase Commitment [Line Items]
Number of extension options | ground_lease	3
Ground lease extension option term		10 years
Forty-five year ground lease extension option [Member]
Long-term Purchase Commitment [Line Items]
Number of extension options | ground_lease	1
Ground lease extension option term	45 years
Environmental matters [Member]
Long-term Purchase Commitment [Line Items]
Accrued environmental remediation liabilities	$ 80.7	$ 83.2

Commitments and Contingencies_2

Commitments and Contingencies - Minimum Commitment Under Ground Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Minimum commitment under our ground leases
2020	$ 5,641
2021	5,641
2022	5,642
2023	5,662
2024	5,662
Thereafter	286,385
Total	314,633
Present value discount	(216,233)
Ground lease liabilities	$ 98,400	$ 98,349
Minimum commitment under our ground leases
2019			$ 5,154
2020			5,154
2021			5,154
2022			5,154
2023			5,154
Thereafter			233,619
Total			$ 259,389

Fair Value Measurements and D_3

Fair Value Measurements and Disclosures - Assets and Liabilities Reported at Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair value adjustment of marketable securities and deferred compensation plan liability
Net gain (loss) on marketable securities	$ 3,885	$ (1,851)	$ 3,023
Fair value, measurements, recurring [Member] | Fair Value (Level 1) [Member]
Assets and Liabilities Reported at Fair Value
Marketable securities	$ 27,098	$ 21,779

Fair Value Measurements and D_4

Fair Value Measurements and Disclosures - Financial Instruments Disclosed at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Carrying value [Member] | Secured debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 258,593	$ 335,531
Carrying value [Member] | Unsecured debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	3,049,185	2,552,070
Carrying value [Member] | Unsecured line of credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	245,000	45,000
Fair value [Member] | Secured debt [Member] | Fair value (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	272,997	335,885
Fair value [Member] | Unsecured debt [Member] | Fair value (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	3,252,217	2,546,386
Fair value [Member] | Unsecured line of credit [Member] | Fair value (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 245,195	$ 45,058

Other Significant Events - Narr

Other Significant Events - Narrative (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)tenant	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues	$ 220,235	$ 215,525	$ 200,492	$ 201,202	$ 190,842	$ 186,562	$ 187,072	$ 182,822	$ 837,454	$ 747,298	$ 719,001
Provision for bad debts									0	5,685	3,269
Provisions for bad debts, increase (decrease)							(1,400)
Tenant one [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for bad debts							$ 7,000
Number of tenants | tenant							1
Rental [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues									826,472	$ 656,631	$ 633,896
Rental [Member] | Accounting Standards Update 2016-02 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues									2,900
Rental [Member] | Accounting Standards Update 2016-02 [Member] | Tenant one [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues									4,200
Rental [Member] | Accounting Standards Update 2016-02 [Member] | Other tenants [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues									$ (1,300)

Net Income Available to Commo_5

Net Income Available to Common Stockholders Per Share of the Company - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income attributable to Kilroy Realty Corporation									$ 195,443	$ 258,415	$ 164,612
Preferred dividends and distributions									0	0	(13,363)
Allocation to participating securities									(2,119)	(2,004)	(1,975)
Numerator for basic and diluted net income available to common stockholders									$ 193,324	$ 256,411	$ 149,274
Denominator:
Basic weighted average vested shares/units outstanding (in shares/units)									103,200,568	99,972,359	98,113,561
Effect of dilutive securities (in shares)									648,600	510,006	613,770
Diluted weighted average vested shares and common stock/ unit equivalents outstanding (in shares/units)									103,849,168	100,482,365	98,727,331
Basic earnings per share:
Net income available to common stockholders per share - basic (in dollars per share)	$ 0.68	$ 0.41	$ 0.41	$ 0.36	$ 1.59	$ 0.34	$ 0.27	$ 0.36	$ 1.87	$ 2.56	$ 1.52
Diluted earnings per share:
Net income available to common stockholders per share - diluted (in dollars per share)	$ 0.67	$ 0.41	$ 0.41	$ 0.36	$ 1.58	$ 0.33	$ 0.27	$ 0.36	$ 1.86	$ 2.55	$ 1.51

Net Income Available to Commo_6

Net Income Available to Common Unitholders Per Unit of the Operating Partnership - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income attributable to Kilroy Realty, L.P.									$ 195,443	$ 258,415	$ 164,612
Preferred dividends and distributions									0	0	(13,363)
Allocation to participating securities									(2,119)	(2,004)	(1,975)
Numerator for basic and diluted net income available to common stockholders									$ 193,324	$ 256,411	$ 149,274
Denominator:
Basic weighted average vested shares/units outstanding (in shares/units)									103,200,568	99,972,359	98,113,561
Effect of dilutive securities (in units)									648,600	510,006	613,770
Diluted weighted average vested shares and common stock/ unit equivalents outstanding (in shares/units)									103,849,168	100,482,365	98,727,331
Basic earnings per unit:
Net income available to common unitholders per unit - basic (in dollars per unit)	$ 0.68	$ 0.41	$ 0.41	$ 0.36	$ 1.59	$ 0.34	$ 0.27	$ 0.36	$ 1.87	$ 2.56	$ 1.52
Diluted earnings per unit:
Net income available to common unitholders per unit - diluted (in dollars per unit)	0.67	0.41	0.41	0.36	1.58	0.33	0.27	0.36	$ 1.86	$ 2.55	$ 1.51
Kilroy Realty L.P. [Member]
Numerator:
Net income attributable to Kilroy Realty, L.P.									$ 198,738	$ 263,210	$ 167,440
Preferred dividends and distributions									0	0	(13,363)
Allocation to participating securities									(2,119)	(2,004)	(1,975)
Numerator for basic and diluted net income available to common stockholders									$ 196,619	$ 261,206	$ 152,102
Denominator:
Basic weighted average vested shares/units outstanding (in shares/units)									105,223,975	102,025,276	100,246,567
Effect of dilutive securities (in units)									648,600	510,006	613,770
Diluted weighted average vested shares and common stock/ unit equivalents outstanding (in shares/units)									105,872,575	102,535,282	100,860,337
Basic earnings per unit:
Net income available to common unitholders per unit - basic (in dollars per unit)	0.68	0.41	0.41	0.36	1.58	0.34	0.27	0.36	$ 1.87	$ 2.56	$ 1.52
Diluted earnings per unit:
Net income available to common unitholders per unit - diluted (in dollars per unit)	$ 0.67	$ 0.41	$ 0.41	$ 0.36	$ 1.57	$ 0.33	$ 0.27	$ 0.36	$ 1.86	$ 2.55	$ 1.51

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information of the Company - Supplemental Cash Flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively	$ 43,607	$ 44,697	$ 67,336
Capitalized interest	77,666	65,627	44,757
Cash paid for amounts included in the measurement of ground lease liabilities	5,224
Cash paid for amounts included in the measurement of ground lease liabilities		4,398	4,809
NON-CASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development properties	162,654	158,626	116,089
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 3)	10,267	40,624	1,443
Tenant improvements funded directly by tenants	10,268	13,968	15,314
Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18)	96,348			$ 96,272
Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18)	98,400			$ 98,349
NON-CASH FINANCING TRANSACTIONS:
Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 13 and 28)	53,219	47,559	43,448
Exchange of common units of the Operating Partnership into shares of the Company’s common stock	$ 78	$ 1,962	$ 10,939

Supplemental Cash Flow Inform_5

Supplemental Cash Flow Information of the Company - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Roll Forward]
Cash and cash equivalents	$ 60,044	$ 51,604	$ 57,649	$ 193,418
Restricted cash	16,300	119,430	9,149	56,711
Cash and cash equivalents and restricted cash	$ 76,344	$ 171,034	$ 66,798	$ 250,129

Supplemental Cash Flow Inform_6

Supplemental Cash Flow Information of the Operating Partnership - Supplemental Cash Flow (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively	$ 43,607	$ 44,697	$ 67,336
Capitalized interest	77,666	65,627	44,757
Cash paid for amounts included in the measurement of ground lease liabilities	5,224
Cash paid for amounts included in the measurement of ground lease liabilities		4,398	4,809
NON-CASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development properties	162,654	158,626	116,089
Assumption of accrued liabilities in connection with acquisitions (Note 3)	10,267	40,624	1,443
Tenant improvements funded directly by tenants	10,268	13,968	15,314
Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18)	96,348			$ 96,272
Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18)	98,400			98,349
NON-CASH FINANCING TRANSACTIONS:
Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 14 and 28)	53,219	47,559	43,448
Kilroy Realty L.P. [Member]
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $77,666, $65,627, and $44,757 as of December 31, 2019, 2018 and 2017, respectively	43,607	44,697	67,336
Capitalized interest	77,666	65,627	44,757
Cash paid for amounts included in the measurement of ground lease liabilities	5,224
Cash paid for amounts included in the measurement of ground lease liabilities		4,398	4,809
NON-CASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development properties	162,654	158,626	116,089
Assumption of accrued liabilities in connection with acquisitions (Note 3)	10,267	40,624	1,443
Tenant improvements funded directly by tenants	10,268	13,968	15,314
Initial measurement of operating right of use ground lease assets (Notes 2, 3 and 18)	96,348			96,272
Initial measurement of operating ground lease liabilities (Notes 2, 3 and 18)	98,400			$ 98,349
NON-CASH FINANCING TRANSACTIONS:
Accrual of dividends and distributions payable to common stockholders and common unitholders (Notes 14 and 28)	$ 53,219	$ 47,559	$ 43,448

Supplemental Cash Flow Inform_7

Supplemental Cash Flow Information of the Operating Partnership - Cash and Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Roll Forward]
Cash and cash equivalents	$ 60,044	$ 51,604	$ 57,649	$ 193,418
Restricted cash	16,300	119,430	9,149	56,711
Cash and cash equivalents and restricted cash	76,344	171,034	66,798	250,129
Kilroy Realty L.P. [Member]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Roll Forward]
Cash and cash equivalents	60,044	51,604	57,649	193,418
Restricted cash	16,300	119,430	9,149	56,711
Cash and cash equivalents and restricted cash	$ 76,344	$ 171,034	$ 66,798	$ 250,129

Tax Treatment of Distribution_2

Tax Treatment of Distributions - Dividends (Details) - $ / shares	Jan. 13, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Dividends declared per common share (in dollars per share)			$ 0.375	$ 0.375	$ 1.91000	$ 1.79	$ 1.65
Dividends paid per common share (in dollars per share)	$ 0.313
Common Stock [Member]
Class of Stock [Line Items]
Dividends declared per common share (in dollars per share)				2.275	1.910	1.790	1.650
Less: Dividends declared in the current year and paid in the following year (in dollars per share)					(0.485)	(0.455)	(0.425)
Add: Dividends declared in the prior year and paid in the current year (in dollars per share)					0.455	0.425	2.275
Dividends paid per common share (in dollars per share)					$ 1.880	$ 1.760	$ 3.500
Special Dividend [Member]
Class of Stock [Line Items]
Dividends declared per common share (in dollars per share)				$ 1.90
Dividends paid per common share (in dollars per share)		$ 1.587

Tax Treatment of Distribution_3

Tax Treatment of Distributions - Dividends Tax Treatment (Details) - $ / shares	Jan. 13, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)	$ 0.313
Capital gains, federal statutory tax rate		20.00%
Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 1.880	$ 1.760	$ 3.500
Tax Treatment, Ordinary income [Member] | Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 0.939	$ 1.474	$ 1.356
Dividends paid per common share, percentage		49.95%	83.73%	70.87%
Tax Treatment, Qualified dividend [Member] | Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 0.004	$ 0.003	$ 0.002
Dividends paid per common share, percentage		0.21%	0.19%	0.11%
Tax Treatment, Return of capital [Member] | Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 0.312	$ 0.275	$ 0.344
Dividends paid per common share, percentage		16.62%	15.64%	18.00%
Tax Treatment, Capital gains [Member] | Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 0.600	$ 0.008	$ 0
Dividends paid per common share, percentage		31.93%	0.44%	0.00%
Tax Treatment, Unrecaptured section 1250 gains [Member] | Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 0.025	$ 0	$ 0.211
Dividends paid per common share, percentage		1.29%	0.00%	11.02%
Tax treatment [Member] | Common Stock [Member]
Income Tax Treatment of Dividends Paid [Line Items]
Dividends paid per common share (in dollars per share)		$ 1.880	$ 1.760	$ 1.913
Dividends paid per common share, percentage		100.00%	100.00%	100.00%

Quarterly Financial Informati_5

Quarterly Financial Information of the Company (Unaudited) - Summarized Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 220,235	$ 215,525	$ 200,492	$ 201,202	$ 190,842	$ 186,562	$ 187,072	$ 182,822	$ 837,454	$ 747,298	$ 719,001
Net income	77,922	48,298	47,215	41,794	166,890	38,310	31,755	40,971	215,229	277,926	180,615
Net income attributable to Kilroy Realty Corporation	72,500	43,846	42,194	36,903	160,220	34,400	27,549	36,246	195,443	258,415	164,612
Net income available to common stockholders	$ 72,500	$ 43,846	$ 42,194	$ 36,903	$ 160,220	$ 34,400	$ 27,549	$ 36,246	$ 195,443	$ 258,415	$ 151,249
Net income available to common stockholders per share/ unit—basic (dollars per share/ unit)	$ 0.68	$ 0.41	$ 0.41	$ 0.36	$ 1.59	$ 0.34	$ 0.27	$ 0.36	$ 1.87	$ 2.56	$ 1.52
Net income available to common stockholders per share/ unit—diluted (dollars per share/ unit)	$ 0.67	$ 0.41	$ 0.41	$ 0.36	$ 1.58	$ 0.33	$ 0.27	$ 0.36	$ 1.86	$ 2.55	$ 1.51

Quarterly Financial Informati_6

Quarterly Financial Information of the Operating Partnership (Unaudited) - Summarized Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 220,235	$ 215,525	$ 200,492	$ 201,202	$ 190,842	$ 186,562	$ 187,072	$ 182,822	$ 837,454	$ 747,298	$ 719,001
Net income	77,922	48,298	47,215	41,794	166,890	38,310	31,755	40,971	215,229	277,926	180,615
Net income attributable to the Operating Partnership	72,500	43,846	42,194	36,903	160,220	34,400	27,549	36,246	195,443	258,415	164,612
Net income available to common stockholders	$ 72,500	$ 43,846	$ 42,194	$ 36,903	$ 160,220	$ 34,400	$ 27,549	$ 36,246	$ 195,443	$ 258,415	$ 151,249
Net income available to common stockholders per share/ unit—basic (dollars per share/ unit)	$ 0.68	$ 0.41	$ 0.41	$ 0.36	$ 1.59	$ 0.34	$ 0.27	$ 0.36	$ 1.87	$ 2.56	$ 1.52
Net income available to common stockholders per share/ unit—diluted (dollars per share/ unit)	$ 0.67	$ 0.41	$ 0.41	$ 0.36	$ 1.58	$ 0.33	$ 0.27	$ 0.36	$ 1.86	$ 2.55	$ 1.51
Kilroy Realty L.P. [Member]
Effect of Fourth Quarter Events [Line Items]
Revenues	$ 220,235	$ 215,525	$ 200,492	$ 201,202	$ 190,842	$ 186,562	$ 187,072	$ 182,822	$ 837,454	$ 747,298	$ 719,001
Net income	77,922	48,298	47,215	41,794	166,890	38,310	31,755	40,971	215,229	277,926	180,615
Net income attributable to the Operating Partnership	73,740	44,589	42,901	37,508	163,309	34,993	28,015	36,893	198,738	263,210	167,440
Net income available to common stockholders	$ 73,740	$ 44,589	$ 42,901	$ 37,508	$ 163,309	$ 34,993	$ 28,015	$ 36,893	$ 198,738	$ 263,210	$ 154,077
Net income available to common stockholders per share/ unit—basic (dollars per share/ unit)	$ 0.68	$ 0.41	$ 0.41	$ 0.36	$ 1.58	$ 0.34	$ 0.27	$ 0.36	$ 1.87	$ 2.56	$ 1.52
Net income available to common stockholders per share/ unit—diluted (dollars per share/ unit)	$ 0.67	$ 0.41	$ 0.41	$ 0.36	$ 1.57	$ 0.33	$ 0.27	$ 0.36	$ 1.86	$ 2.55	$ 1.51

Subsequent Events - Narrative (

Subsequent Events - Narrative (Details) - USD ($) $ in Millions	Jan. 31, 2020	Jan. 15, 2020	Dec. 31, 2019
Kilroy Realty 2006 Incentive Award Plan [Member]
Subsequent Event [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant			400,000
Subsequent event [Member]
Subsequent Event [Line Items]
Payments of dividends		$ 53.2
Subsequent event [Member] | Kilroy Realty 2006 Incentive Award Plan [Member] | Time-Based Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member]
Subsequent Event [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	109,359
Subsequent event [Member] | Kilroy Realty 2006 Incentive Award Plan [Member] | Market measure-based Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member]
Subsequent Event [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	154,267
Recognition period	3 years

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts - Allowances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Notes receivable, valuation allowance	$ 700
Notes receivable, valuation allowance	3,600	$ 2,900
Uncollectible tenant receivables [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period (1)	4,639	2,309	$ 1,712
Balance at Beginning of Period (1)	512
Charged to Costs and Expenses	907	2,604	1,517
Recoveries (Deductions)	(248)	(274)	(920)
Balance at End of Period	1,171	4,639	2,309
Balance at End of Period		512
Allowance for deferred rent [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period (1)	3,339	3,238	1,524
Balance at Beginning of Period (1)	195
Charged to Costs and Expenses	1,357	165	1,752
Recoveries (Deductions)	0	(64)	(38)
Balance at End of Period	$ 1,552	3,339	$ 3,238
Balance at End of Period		$ 195

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation - Schedule of Real Estate and Accumulated Depreciation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)	Dec. 21, 2018ft²	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances	$ 259,502
Initial cost, land and improvements	2,472,173
Initial cost, buildings and Improvements	2,717,671
Costs capitalized subsequent to acquisition/ improvement	4,438,929
Land and improvements, gross	2,524,342
Buildings and improvements, gross	7,104,432
Land and improvements and buildings and improvements, gross	9,628,773
Accumulated depreciation	$ 1,561,361	$ 1,391,368		$ 1,264,162	$ 1,139,853
Rentable square feet | ft²	13,475,795
345 Brannan Street, San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Rentable square feet | ft²			110,050
Office Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances	$ 259,502
Initial cost, land and improvements	1,413,997
Initial cost, buildings and Improvements	2,717,671
Costs capitalized subsequent to acquisition/ improvement	3,200,975
Land and improvements, gross	1,466,166
Buildings and improvements, gross	5,866,477
Land and improvements and buildings and improvements, gross	7,332,643
Accumulated depreciation	$ 1,561,361
Rentable square feet | ft²	13,475,795
Office Building [Member] | 3077-3243 S. La Cienega Blvd., Culver City, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 150,718
Initial cost, buildings and Improvements	31,032
Costs capitalized subsequent to acquisition/ improvement	2
Land and improvements, gross	150,718
Buildings and improvements, gross	31,034
Land and improvements and buildings and improvements, gross	181,752
Accumulated depreciation	$ 1,227
Depreciation life	35 years
Rentable square feet | ft²	151,908
Office Building [Member] | 2240 E. Imperial Highway, El Segundo, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,044
Initial cost, buildings and Improvements	11,763
Costs capitalized subsequent to acquisition/ improvement	29,542
Land and improvements, gross	1,048
Buildings and improvements, gross	41,301
Land and improvements and buildings and improvements, gross	42,349
Accumulated depreciation	$ 26,943
Depreciation life	35 years
Rentable square feet | ft²	122,870
Office Building [Member] | 2250 E. Imperial Highway, El Segundo, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 2,579
Initial cost, buildings and Improvements	29,062
Costs capitalized subsequent to acquisition/ improvement	36,294
Land and improvements, gross	2,547
Buildings and improvements, gross	65,388
Land and improvements and buildings and improvements, gross	67,935
Accumulated depreciation	$ 54,789
Depreciation life	35 years
Rentable square feet | ft²	298,728
Office Building [Member] | 2260 E. Imperial Highway, El Segundo, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 2,518
Initial cost, buildings and Improvements	28,370
Costs capitalized subsequent to acquisition/ improvement	36,764
Land and improvements, gross	2,547
Buildings and improvements, gross	65,105
Land and improvements and buildings and improvements, gross	67,652
Accumulated depreciation	$ 16,320
Depreciation life	35 years
Rentable square feet | ft²	298,728
Office Building [Member] | 909 N. Pacific Coast Highway, El Segundo, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 3,577
Initial cost, buildings and Improvements	34,042
Costs capitalized subsequent to acquisition/ improvement	50,104
Land and improvements, gross	3,577
Buildings and improvements, gross	84,146
Land and improvements and buildings and improvements, gross	87,723
Accumulated depreciation	$ 41,765
Depreciation life	35 years
Rentable square feet | ft²	244,136
Office Building [Member] | 999 N. Pacific Coast Highway, El Segundo, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,407
Initial cost, buildings and Improvements	34,326
Costs capitalized subsequent to acquisition/ improvement	16,897
Land and improvements, gross	1,407
Buildings and improvements, gross	51,223
Land and improvements and buildings and improvements, gross	52,630
Accumulated depreciation	$ 25,350
Depreciation life	35 years
Rentable square feet | ft²	128,588
Office Building [Member] | 6115 W. Sunset Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,313
Initial cost, buildings and Improvements	3
Costs capitalized subsequent to acquisition/ improvement	16,436
Land and improvements, gross	2,455
Buildings and improvements, gross	15,297
Land and improvements and buildings and improvements, gross	17,752
Accumulated depreciation	$ 2,165
Depreciation life	35 years
Rentable square feet | ft²	26,105
Office Building [Member] | 6121 W. Sunset Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 11,120
Initial cost, buildings and Improvements	4,256
Costs capitalized subsequent to acquisition/ improvement	43,971
Land and improvements, gross	8,703
Buildings and improvements, gross	50,644
Land and improvements and buildings and improvements, gross	59,347
Accumulated depreciation	$ 7,262
Depreciation life	35 years
Rentable square feet | ft²	91,173
Office Building [Member] | 1525 N. Gower Street, Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,318
Initial cost, buildings and Improvements	3
Costs capitalized subsequent to acquisition/ improvement	9,641
Land and improvements, gross	1,318
Buildings and improvements, gross	9,644
Land and improvements and buildings and improvements, gross	10,962
Accumulated depreciation	$ 1,206
Depreciation life	35 years
Rentable square feet | ft²	9,610
Office Building [Member] | 1575 N. Gower Street, Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 22,153
Initial cost, buildings and Improvements	51
Costs capitalized subsequent to acquisition/ improvement	119,460
Land and improvements, gross	22,153
Buildings and improvements, gross	119,511
Land and improvements and buildings and improvements, gross	141,664
Accumulated depreciation	$ 11,813
Depreciation life	35 years
Rentable square feet | ft²	251,245
Office Building [Member] | 1500 N. El Centro Avenue, Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 9,235
Initial cost, buildings and Improvements	21
Costs capitalized subsequent to acquisition/ improvement	58,603
Land and improvements, gross	9,235
Buildings and improvements, gross	58,624
Land and improvements and buildings and improvements, gross	67,859
Accumulated depreciation	$ 6,208
Depreciation life	35 years
Rentable square feet | ft²	104,504
Office Building [Member] | 1550 N. El Centro Avenue, Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 16,970
Initial cost, buildings and Improvements	39
Costs capitalized subsequent to acquisition/ improvement	135,847
Land and improvements, gross	16,970
Buildings and improvements, gross	135,886
Land and improvements and buildings and improvements, gross	152,856
Accumulated depreciation	$ 13,895
Depreciation life	35 years
Rentable square feet | ft²	0
Office Building [Member] | 6255 W. Sunset Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 18,111
Initial cost, buildings and Improvements	60,320
Costs capitalized subsequent to acquisition/ improvement	46,112
Land and improvements, gross	18,111
Buildings and improvements, gross	106,432
Land and improvements and buildings and improvements, gross	124,543
Accumulated depreciation	$ 35,548
Depreciation life	35 years
Rentable square feet | ft²	323,920
Office Building [Member] | 3750 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	1,941
Costs capitalized subsequent to acquisition/ improvement	11,610
Land and improvements, gross	0
Buildings and improvements, gross	13,551
Land and improvements and buildings and improvements, gross	13,551
Accumulated depreciation	$ 10,822
Depreciation life	35 years
Rentable square feet | ft²	10,457
Office Building [Member] | 3760 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	17,467
Costs capitalized subsequent to acquisition/ improvement	14,902
Land and improvements, gross	0
Buildings and improvements, gross	32,369
Land and improvements and buildings and improvements, gross	32,369
Accumulated depreciation	$ 26,878
Depreciation life	35 years
Rentable square feet | ft²	165,278
Office Building [Member] | 3780 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	22,319
Costs capitalized subsequent to acquisition/ improvement	26,442
Land and improvements, gross	0
Buildings and improvements, gross	48,761
Land and improvements and buildings and improvements, gross	48,761
Accumulated depreciation	$ 39,320
Depreciation life	35 years
Rentable square feet | ft²	221,452
Office Building [Member] | 3800 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	19,408
Costs capitalized subsequent to acquisition/ improvement	21,806
Land and improvements, gross	0
Buildings and improvements, gross	41,214
Land and improvements and buildings and improvements, gross	41,214
Accumulated depreciation	$ 24,877
Depreciation life	35 years
Rentable square feet | ft²	192,476
Office Building [Member] | 3840 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	13,586
Costs capitalized subsequent to acquisition/ improvement	10,666
Land and improvements, gross	0
Buildings and improvements, gross	24,252
Land and improvements and buildings and improvements, gross	24,252
Accumulated depreciation	$ 16,162
Depreciation life	35 years
Rentable square feet | ft²	136,026
Office Building [Member] | 3880 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	9,704
Costs capitalized subsequent to acquisition/ improvement	11,463
Land and improvements, gross	0
Buildings and improvements, gross	21,167
Land and improvements and buildings and improvements, gross	21,167
Accumulated depreciation	$ 4,517
Depreciation life	35 years
Rentable square feet | ft²	96,035
Office Building [Member] | 3900 Kilroy Airport Way, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	12,615
Costs capitalized subsequent to acquisition/ improvement	12,433
Land and improvements, gross	0
Buildings and improvements, gross	25,048
Land and improvements and buildings and improvements, gross	25,048
Accumulated depreciation	$ 18,248
Depreciation life	35 years
Rentable square feet | ft²	129,893
Office Building [Member] | Kilroy Airport Center, Phase IV, Long Beach, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	4,997
Land and improvements, gross	0
Buildings and improvements, gross	4,997
Land and improvements and buildings and improvements, gross	4,997
Accumulated depreciation	$ 4,997
Depreciation life	35 years
Rentable square feet | ft²	0
Office Building [Member] | 8560 W. Sunset Blvd, West Hollywood, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 9,720
Initial cost, buildings and Improvements	50,956
Costs capitalized subsequent to acquisition/ improvement	1,587
Land and improvements, gross	9,720
Buildings and improvements, gross	52,543
Land and improvements and buildings and improvements, gross	62,263
Accumulated depreciation	$ 6,289
Depreciation life	35 years
Rentable square feet | ft²	71,875
Office Building [Member] | 8570 W. Sunset Blvd, West Hollywood, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 31,693
Initial cost, buildings and Improvements	27,974
Costs capitalized subsequent to acquisition/ improvement	4,589
Land and improvements, gross	31,693
Buildings and improvements, gross	32,563
Land and improvements and buildings and improvements, gross	64,256
Accumulated depreciation	$ 3,090
Depreciation life	35 years
Rentable square feet | ft²	43,603
Office Building [Member] | 8580 W. Sunset Blvd, West Hollywood, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 10,013
Initial cost, buildings and Improvements	3,695
Costs capitalized subsequent to acquisition/ improvement	648
Land and improvements, gross	10,013
Buildings and improvements, gross	4,343
Land and improvements and buildings and improvements, gross	14,356
Accumulated depreciation	$ 392
Depreciation life	35 years
Rentable square feet | ft²	7,126
Office Building [Member] | 8590 W. Sunset Blvd, West Hollywood, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 39,954
Initial cost, buildings and Improvements	27,884
Costs capitalized subsequent to acquisition/ improvement	5,192
Land and improvements, gross	39,954
Buildings and improvements, gross	33,076
Land and improvements and buildings and improvements, gross	73,030
Accumulated depreciation	$ 3,370
Depreciation life	35 years
Rentable square feet | ft²	56,095
Office Building [Member] | 12100 W. Olympic Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances	$ 170,000
Initial cost, land and improvements	352
Initial cost, buildings and Improvements	45,611
Costs capitalized subsequent to acquisition/ improvement	18,617
Land and improvements, gross	9,633
Buildings and improvements, gross	54,947
Land and improvements and buildings and improvements, gross	64,580
Accumulated depreciation	$ 29,197
Depreciation life	35 years
Rentable square feet | ft²	152,048
Office Building [Member] | 12200 W. Olympic Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,329
Initial cost, buildings and Improvements	35,488
Costs capitalized subsequent to acquisition/ improvement	24,224
Land and improvements, gross	3,977
Buildings and improvements, gross	60,064
Land and improvements and buildings and improvements, gross	64,041
Accumulated depreciation	$ 39,654
Depreciation life	35 years
Rentable square feet | ft²	150,832
Office Building [Member] | 12233 Olympic Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 22,100
Initial cost, buildings and Improvements	53,170
Costs capitalized subsequent to acquisition/ improvement	4,676
Land and improvements, gross	22,100
Buildings and improvements, gross	57,846
Land and improvements and buildings and improvements, gross	79,946
Accumulated depreciation	$ 14,055
Depreciation life	35 years
Rentable square feet | ft²	151,029
Office Building [Member] | 12312 W. Olympic Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 3,325
Initial cost, buildings and Improvements	12,202
Costs capitalized subsequent to acquisition/ improvement	12,346
Land and improvements, gross	3,399
Buildings and improvements, gross	24,474
Land and improvements and buildings and improvements, gross	27,873
Accumulated depreciation	$ 13,463
Depreciation life	35 years
Rentable square feet | ft²	76,644
Office Building [Member] | 1633 26th St., Santa Monica, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 2,080
Initial cost, buildings and Improvements	6,672
Costs capitalized subsequent to acquisition/ improvement	3,581
Land and improvements, gross	2,040
Buildings and improvements, gross	10,293
Land and improvements and buildings and improvements, gross	12,333
Accumulated depreciation	$ 7,177
Depreciation life	35 years
Rentable square feet | ft²	43,857
Office Building [Member] | 2100/2110 Colorado Ave., Santa Monica, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 5,474
Initial cost, buildings and Improvements	26,087
Costs capitalized subsequent to acquisition/ improvement	14,678
Land and improvements, gross	5,476
Buildings and improvements, gross	40,763
Land and improvements and buildings and improvements, gross	46,239
Accumulated depreciation	$ 25,730
Depreciation life	35 years
Rentable square feet | ft²	102,864
Office Building [Member] | 3130 Wilshire Blvd., Santa Monica, [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 8,921
Initial cost, buildings and Improvements	6,579
Costs capitalized subsequent to acquisition/ improvement	16,799
Land and improvements, gross	9,188
Buildings and improvements, gross	23,111
Land and improvements and buildings and improvements, gross	32,299
Accumulated depreciation	$ 15,989
Depreciation life	35 years
Rentable square feet | ft²	90,074
Office Building [Member] | 501 Santa Monica Blvd., Santa Monica, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,547
Initial cost, buildings and Improvements	12,044
Costs capitalized subsequent to acquisition/ improvement	15,889
Land and improvements, gross	4,551
Buildings and improvements, gross	27,929
Land and improvements and buildings and improvements, gross	32,480
Accumulated depreciation	$ 17,346
Depreciation life	35 years
Rentable square feet | ft²	76,803
Office Building [Member] | 12225 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,700
Initial cost, buildings and Improvements	9,633
Costs capitalized subsequent to acquisition/ improvement	3,714
Land and improvements, gross	1,673
Buildings and improvements, gross	13,374
Land and improvements and buildings and improvements, gross	15,047
Accumulated depreciation	$ 9,224
Depreciation life	35 years
Rentable square feet | ft²	58,401
Office Building [Member] | 12235 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,507
Initial cost, buildings and Improvements	8,543
Costs capitalized subsequent to acquisition/ improvement	9,022
Land and improvements, gross	1,540
Buildings and improvements, gross	17,532
Land and improvements and buildings and improvements, gross	19,072
Accumulated depreciation	$ 10,435
Depreciation life	35 years
Rentable square feet | ft²	53,751
Office Building [Member] | 12340 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,201
Initial cost, buildings and Improvements	13,896
Costs capitalized subsequent to acquisition/ improvement	11,660
Land and improvements, gross	4,201
Buildings and improvements, gross	25,556
Land and improvements and buildings and improvements, gross	29,757
Accumulated depreciation	$ 12,128
Depreciation life	35 years
Rentable square feet | ft²	89,272
Office Building [Member] | 12390 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 3,453
Initial cost, buildings and Improvements	11,981
Costs capitalized subsequent to acquisition/ improvement	8,804
Land and improvements, gross	3,453
Buildings and improvements, gross	20,785
Land and improvements and buildings and improvements, gross	24,238
Accumulated depreciation	$ 9,540
Depreciation life	35 years
Rentable square feet | ft²	70,140
Office Building [Member] | 12348 High Bluff Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,629
Initial cost, buildings and Improvements	3,096
Costs capitalized subsequent to acquisition/ improvement	6,323
Land and improvements, gross	1,629
Buildings and improvements, gross	9,419
Land and improvements and buildings and improvements, gross	11,048
Accumulated depreciation	$ 6,636
Depreciation life	35 years
Rentable square feet | ft²	38,806
Office Building [Member] | 12400 High Bluff Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 15,167
Initial cost, buildings and Improvements	40,497
Costs capitalized subsequent to acquisition/ improvement	14,473
Land and improvements, gross	15,167
Buildings and improvements, gross	54,970
Land and improvements and buildings and improvements, gross	70,137
Accumulated depreciation	$ 28,866
Depreciation life	35 years
Rentable square feet | ft²	209,220
Office Building [Member] | 3579 Valley Centre Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 2,167
Initial cost, buildings and Improvements	6,897
Costs capitalized subsequent to acquisition/ improvement	7,628
Land and improvements, gross	2,858
Buildings and improvements, gross	13,834
Land and improvements and buildings and improvements, gross	16,692
Accumulated depreciation	$ 10,015
Depreciation life	35 years
Rentable square feet | ft²	54,960
Office Building [Member] | 3611 Valley Centre Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,184
Initial cost, buildings and Improvements	19,352
Costs capitalized subsequent to acquisition/ improvement	19,881
Land and improvements, gross	5,259
Buildings and improvements, gross	38,158
Land and improvements and buildings and improvements, gross	43,417
Accumulated depreciation	$ 25,713
Depreciation life	35 years
Rentable square feet | ft²	129,656
Office Building [Member] | 3661 Valley Centre Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,038
Initial cost, buildings and Improvements	21,144
Costs capitalized subsequent to acquisition/ improvement	18,843
Land and improvements, gross	4,725
Buildings and improvements, gross	39,300
Land and improvements and buildings and improvements, gross	44,025
Accumulated depreciation	$ 22,291
Depreciation life	35 years
Rentable square feet | ft²	128,364
Office Building [Member] | 3721 Valley Centre Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,297
Initial cost, buildings and Improvements	18,967
Costs capitalized subsequent to acquisition/ improvement	14,705
Land and improvements, gross	4,254
Buildings and improvements, gross	33,715
Land and improvements and buildings and improvements, gross	37,969
Accumulated depreciation	$ 17,509
Depreciation life	35 years
Rentable square feet | ft²	115,193
Office Building [Member] | 3811 Valley Centre Dr., Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 3,452
Initial cost, buildings and Improvements	16,152
Costs capitalized subsequent to acquisition/ improvement	20,234
Land and improvements, gross	4,457
Buildings and improvements, gross	35,381
Land and improvements and buildings and improvements, gross	39,838
Accumulated depreciation	$ 22,848
Depreciation life	35 years
Rentable square feet | ft²	112,067
Office Building [Member] | 12770 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 9,360
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	33,708
Land and improvements, gross	9,360
Buildings and improvements, gross	33,708
Land and improvements and buildings and improvements, gross	43,068
Accumulated depreciation	$ 3,281
Depreciation life	35 years
Rentable square feet | ft²	73,032
Office Building [Member] | 12780 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 18,398
Initial cost, buildings and Improvements	54,954
Costs capitalized subsequent to acquisition/ improvement	19,637
Land and improvements, gross	18,398
Buildings and improvements, gross	74,591
Land and improvements and buildings and improvements, gross	92,989
Accumulated depreciation	$ 15,891
Depreciation life	35 years
Rentable square feet | ft²	140,591
Office Building [Member] | 12790 El Camino Real, Del Mar, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 10,252
Initial cost, buildings and Improvements	21,236
Costs capitalized subsequent to acquisition/ improvement	1,915
Land and improvements, gross	10,252
Buildings and improvements, gross	23,151
Land and improvements and buildings and improvements, gross	33,403
Accumulated depreciation	$ 5,768
Depreciation life	35 years
Rentable square feet | ft²	78,836
Office Building [Member] | 3745 Paseo Place, Del Mar, CA (Retail) [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 24,358
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	71,800
Land and improvements, gross	24,358
Buildings and improvements, gross	71,800
Land and improvements and buildings and improvements, gross	96,158
Accumulated depreciation	$ 1,683
Depreciation life	35 years
Rentable square feet | ft²	0
Office Building [Member] | 3200 Paseo Village Way, San Diego, CA (Resi Phase I) (16) [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 40,186
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	102,749
Land and improvements, gross	40,186
Buildings and improvements, gross	102,749
Land and improvements and buildings and improvements, gross	142,935
Accumulated depreciation	$ 937
Depreciation life	35 years
Rentable square feet | ft²	0
Office Building [Member] | 13280 Evening Creek Dr. South, I-15 Corridor, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 3,701
Initial cost, buildings and Improvements	8,398
Costs capitalized subsequent to acquisition/ improvement	4,729
Land and improvements, gross	3,701
Buildings and improvements, gross	13,127
Land and improvements and buildings and improvements, gross	16,828
Accumulated depreciation	$ 5,809
Depreciation life	35 years
Rentable square feet | ft²	41,196
Office Building [Member] | 13290 Evening Creek Dr. South, I-15 Corridor, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 5,229
Initial cost, buildings and Improvements	11,871
Costs capitalized subsequent to acquisition/ improvement	6,128
Land and improvements, gross	5,229
Buildings and improvements, gross	17,999
Land and improvements and buildings and improvements, gross	23,228
Accumulated depreciation	$ 6,797
Depreciation life	35 years
Rentable square feet | ft²	61,180
Office Building [Member] | 13480 Evening Creek Dr. South, I-15 Corridor, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 7,997
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	52,826
Land and improvements, gross	7,997
Buildings and improvements, gross	52,826
Land and improvements and buildings and improvements, gross	60,823
Accumulated depreciation	$ 20,167
Depreciation life	35 years
Rentable square feet | ft²	154,157
Office Building [Member] | 13500 Evening Creek Dr. South, I-15 Corridor, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 7,581
Initial cost, buildings and Improvements	35,903
Costs capitalized subsequent to acquisition/ improvement	18,106
Land and improvements, gross	7,581
Buildings and improvements, gross	54,009
Land and improvements and buildings and improvements, gross	61,590
Accumulated depreciation	$ 22,402
Depreciation life	35 years
Rentable square feet | ft²	137,658
Office Building [Member] | 13520 Evening Creek Dr. South, I-15 Corridor, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 7,580
Initial cost, buildings and Improvements	35,903
Costs capitalized subsequent to acquisition/ improvement	17,778
Land and improvements, gross	7,580
Buildings and improvements, gross	53,681
Land and improvements and buildings and improvements, gross	61,261
Accumulated depreciation	$ 24,885
Depreciation life	35 years
Rentable square feet | ft²	146,701
Office Building [Member] | 2305 Historic Decatur Rd., Point Loma, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 5,240
Initial cost, buildings and Improvements	22,220
Costs capitalized subsequent to acquisition/ improvement	7,309
Land and improvements, gross	5,240
Buildings and improvements, gross	29,529
Land and improvements and buildings and improvements, gross	34,769
Accumulated depreciation	$ 10,801
Depreciation life	35 years
Rentable square feet | ft²	107,456
Office Building [Member] | 4690 Executive Dr., University Towne Centre, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 1,623
Initial cost, buildings and Improvements	7,926
Costs capitalized subsequent to acquisition/ improvement	3,722
Land and improvements, gross	1,623
Buildings and improvements, gross	11,648
Land and improvements and buildings and improvements, gross	13,271
Accumulated depreciation	$ 7,829
Depreciation life	35 years
Rentable square feet | ft²	47,846
Office Building [Member] | Bohannon Drive 4100, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,835
Initial cost, buildings and Improvements	15,526
Costs capitalized subsequent to acquisition/ improvement	567
Land and improvements, gross	4,860
Buildings and improvements, gross	16,068
Land and improvements and buildings and improvements, gross	20,928
Accumulated depreciation	$ 4,557
Depreciation life	35 years
Rentable square feet | ft²	47,379
Office Building [Member] | Bohannon Drive 4200, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,798
Initial cost, buildings and Improvements	15,406
Costs capitalized subsequent to acquisition/ improvement	3,703
Land and improvements, gross	4,662
Buildings and improvements, gross	19,245
Land and improvements and buildings and improvements, gross	23,907
Accumulated depreciation	$ 5,788
Depreciation life	35 years
Rentable square feet | ft²	45,451
Office Building [Member] | Bohannon Drive 4300, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 6,527
Initial cost, buildings and Improvements	20,958
Costs capitalized subsequent to acquisition/ improvement	3,248
Land and improvements, gross	6,470
Buildings and improvements, gross	24,263
Land and improvements and buildings and improvements, gross	30,733
Accumulated depreciation	$ 7,803
Depreciation life	35 years
Rentable square feet | ft²	63,079
Office Building [Member] | Bohannon Drive 4400, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,798
Initial cost, buildings and Improvements	15,406
Costs capitalized subsequent to acquisition/ improvement	2,905
Land and improvements, gross	4,939
Buildings and improvements, gross	18,170
Land and improvements and buildings and improvements, gross	23,109
Accumulated depreciation	$ 5,779
Depreciation life	35 years
Rentable square feet | ft²	48,146
Office Building [Member] | Bohannon Drive 4500, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 6,527
Initial cost, buildings and Improvements	20,957
Costs capitalized subsequent to acquisition/ improvement	3,422
Land and improvements, gross	6,470
Buildings and improvements, gross	24,436
Land and improvements and buildings and improvements, gross	30,906
Accumulated depreciation	$ 6,552
Depreciation life	35 years
Rentable square feet | ft²	63,078
Office Building [Member] | Bohannon Drive 4600, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 4,798
Initial cost, buildings and Improvements	15,406
Costs capitalized subsequent to acquisition/ improvement	3,571
Land and improvements, gross	4,939
Buildings and improvements, gross	18,836
Land and improvements and buildings and improvements, gross	23,775
Accumulated depreciation	$ 5,660
Depreciation life	35 years
Rentable square feet | ft²	48,147
Office Building [Member] | Bohannon Drive 4700, Menlo Park, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 6,527
Initial cost, buildings and Improvements	20,958
Costs capitalized subsequent to acquisition/ improvement	1,488
Land and improvements, gross	6,470
Buildings and improvements, gross	22,503
Land and improvements and buildings and improvements, gross	28,973
Accumulated depreciation	$ 6,326
Depreciation life	35 years
Rentable square feet | ft²	63,078
Office Building [Member] | 1290-1300 Terra Bella Avenue, Mountain View, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 28,730
Initial cost, buildings and Improvements	27,555
Costs capitalized subsequent to acquisition/ improvement	61
Land and improvements, gross	28,730
Buildings and improvements, gross	27,616
Land and improvements and buildings and improvements, gross	56,346
Accumulated depreciation	$ 4,809
Depreciation life	35 years
Rentable square feet | ft²	114,175
Office Building [Member] | 331 Fairchild Dr., Mountain View, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 18,396
Initial cost, buildings and Improvements	17,712
Costs capitalized subsequent to acquisition/ improvement	7,962
Land and improvements, gross	18,396
Buildings and improvements, gross	25,674
Land and improvements and buildings and improvements, gross	44,070
Accumulated depreciation	$ 5,575
Depreciation life	35 years
Rentable square feet | ft²	87,147
Office Building [Member] | 680 E Middlefield Road, Mountain View, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 34,605
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	56,470
Land and improvements, gross	34,605
Buildings and improvements, gross	56,470
Land and improvements and buildings and improvements, gross	91,075
Accumulated depreciation	$ 9,813
Depreciation life	35 years
Rentable square feet | ft²	170,090
Office Building [Member] | 690 E Middlefield Road, Mountain View, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 34,755
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	56,713
Land and improvements, gross	34,755
Buildings and improvements, gross	56,713
Land and improvements and buildings and improvements, gross	91,468
Accumulated depreciation	$ 9,855
Depreciation life	35 years
Rentable square feet | ft²	170,823
Office Building [Member] | 1701 Page Mill Rd, Palo Alto, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	99,522
Costs capitalized subsequent to acquisition/ improvement	30
Land and improvements, gross	0
Buildings and improvements, gross	99,552
Land and improvements and buildings and improvements, gross	99,552
Accumulated depreciation	$ 9,002
Depreciation life	35 years
Rentable square feet | ft²	128,688
Office Building [Member] | 3150 Porter Drive, Palo Alto, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	21,715
Costs capitalized subsequent to acquisition/ improvement	4
Land and improvements, gross	0
Buildings and improvements, gross	21,719
Land and improvements and buildings and improvements, gross	21,719
Accumulated depreciation	$ 2,387
Depreciation life	35 years
Rentable square feet | ft²	36,897
Office Building [Member] | 900 Jefferson Ave., Redwood City, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 16,668
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	109,375
Land and improvements, gross	18,063
Buildings and improvements, gross	107,980
Land and improvements and buildings and improvements, gross	126,043
Accumulated depreciation	$ 15,824
Depreciation life	35 years
Rentable square feet | ft²	228,505
Office Building [Member] | 900 Middlefield Road, Redwood City, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 7,959
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	50,114
Land and improvements, gross	8,626
Buildings and improvements, gross	49,447
Land and improvements and buildings and improvements, gross	58,073
Accumulated depreciation	$ 6,941
Depreciation life	35 years
Rentable square feet | ft²	118,764
Office Building [Member] | 303 Second St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 63,550
Initial cost, buildings and Improvements	154,153
Costs capitalized subsequent to acquisition/ improvement	84,572
Land and improvements, gross	63,550
Buildings and improvements, gross	238,725
Land and improvements and buildings and improvements, gross	302,275
Accumulated depreciation	$ 83,973
Depreciation life	35 years
Rentable square feet | ft²	784,658
Office Building [Member] | 100 First St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 49,150
Initial cost, buildings and Improvements	131,238
Costs capitalized subsequent to acquisition/ improvement	64,883
Land and improvements, gross	49,150
Buildings and improvements, gross	196,121
Land and improvements and buildings and improvements, gross	245,271
Accumulated depreciation	$ 62,989
Depreciation life	35 years
Rentable square feet | ft²	467,095
Office Building [Member] | 250 Brannan St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 7,630
Initial cost, buildings and Improvements	22,770
Costs capitalized subsequent to acquisition/ improvement	9,932
Land and improvements, gross	7,630
Buildings and improvements, gross	32,702
Land and improvements and buildings and improvements, gross	40,332
Accumulated depreciation	$ 10,651
Depreciation life	35 years
Rentable square feet | ft²	100,850
Office Building [Member] | 201 Third St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 19,260
Initial cost, buildings and Improvements	84,018
Costs capitalized subsequent to acquisition/ improvement	66,962
Land and improvements, gross	19,260
Buildings and improvements, gross	150,980
Land and improvements and buildings and improvements, gross	170,240
Accumulated depreciation	$ 55,837
Depreciation life	35 years
Rentable square feet | ft²	346,538
Office Building [Member] | 301 Brannan St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 5,910
Initial cost, buildings and Improvements	22,450
Costs capitalized subsequent to acquisition/ improvement	8,174
Land and improvements, gross	5,910
Buildings and improvements, gross	30,624
Land and improvements and buildings and improvements, gross	36,534
Accumulated depreciation	$ 10,091
Depreciation life	35 years
Rentable square feet | ft²	82,834
Office Building [Member] | 360 Third St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	88,235
Costs capitalized subsequent to acquisition/ improvement	121,323
Land and improvements, gross	28,504
Buildings and improvements, gross	181,054
Land and improvements and buildings and improvements, gross	209,558
Accumulated depreciation	$ 46,907
Depreciation life	35 years
Rentable square feet | ft²	429,796
Office Building [Member] | 333 Brannan St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 18,645
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	81,016
Land and improvements, gross	18,645
Buildings and improvements, gross	81,016
Land and improvements and buildings and improvements, gross	99,661
Accumulated depreciation	$ 8,826
Depreciation life	35 years
Rentable square feet | ft²	185,602
Office Building [Member] | 350 Mission St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 52,815
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	213,450
Land and improvements, gross	52,815
Buildings and improvements, gross	213,450
Land and improvements and buildings and improvements, gross	266,265
Accumulated depreciation	$ 24,500
Depreciation life	35 years
Rentable square feet | ft²	455,340
Office Building [Member] | 100 Hooper Street, San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 78,564
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	196,251
Land and improvements, gross	88,510
Buildings and improvements, gross	186,305
Land and improvements and buildings and improvements, gross	274,815
Accumulated depreciation	$ 5,978
Depreciation life	35 years
Rentable square feet | ft²	394,340
Office Building [Member] | 345 Brannan Street, San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 29,405
Initial cost, buildings and Improvements	113,179
Costs capitalized subsequent to acquisition/ improvement	1,322
Land and improvements, gross	29,403
Buildings and improvements, gross	114,503
Land and improvements and buildings and improvements, gross	143,906
Accumulated depreciation	$ 3,697
Depreciation life	35 years
Rentable square feet | ft²	110,050
Office Building [Member] | 345 Oyster Point Blvd., South San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 13,745
Initial cost, buildings and Improvements	18,575
Costs capitalized subsequent to acquisition/ improvement	1
Land and improvements, gross	13,745
Buildings and improvements, gross	18,576
Land and improvements and buildings and improvements, gross	32,321
Accumulated depreciation	$ 1,167
Depreciation life	35 years
Rentable square feet | ft²	40,410
Office Building [Member] | 347 Oyster Point Blvd., South San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 14,071
Initial cost, buildings and Improvements	18,289
Costs capitalized subsequent to acquisition/ improvement	44
Land and improvements, gross	14,071
Buildings and improvements, gross	18,333
Land and improvements and buildings and improvements, gross	32,404
Accumulated depreciation	$ 1,150
Depreciation life	35 years
Rentable square feet | ft²	39,780
Office Building [Member] | 349 Oyster Point Blvd., South San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 23,112
Initial cost, buildings and Improvements	22,601
Costs capitalized subsequent to acquisition/ improvement	324
Land and improvements, gross	23,112
Buildings and improvements, gross	22,925
Land and improvements and buildings and improvements, gross	46,037
Accumulated depreciation	$ 1,926
Depreciation life	35 years
Rentable square feet | ft²	65,340
Office Building [Member] | 505 Mathilda Ave., Sunnyvale, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 37,843
Initial cost, buildings and Improvements	1,163
Costs capitalized subsequent to acquisition/ improvement	50,450
Land and improvements, gross	37,943
Buildings and improvements, gross	51,513
Land and improvements and buildings and improvements, gross	89,456
Accumulated depreciation	$ 7,827
Depreciation life	35 years
Rentable square feet | ft²	212,322
Office Building [Member] | 555 Mathilda Ave., Sunnyvale, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 37,843
Initial cost, buildings and Improvements	1,163
Costs capitalized subsequent to acquisition/ improvement	50,447
Land and improvements, gross	37,943
Buildings and improvements, gross	51,510
Land and improvements and buildings and improvements, gross	89,453
Accumulated depreciation	$ 7,827
Depreciation life	35 years
Rentable square feet | ft²	212,322
Office Building [Member] | 605 Mathilda Ave., Sunnyvale, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 29,014
Initial cost, buildings and Improvements	891
Costs capitalized subsequent to acquisition/ improvement	77,281
Land and improvements, gross	29,090
Buildings and improvements, gross	78,096
Land and improvements and buildings and improvements, gross	107,186
Accumulated depreciation	$ 17,289
Depreciation life	35 years
Rentable square feet | ft²	162,785
Office Building [Member] | 599 Mathilda Ave., Sunnyvale, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 13,538
Initial cost, buildings and Improvements	12,559
Costs capitalized subsequent to acquisition/ improvement	139
Land and improvements, gross	13,538
Buildings and improvements, gross	12,698
Land and improvements and buildings and improvements, gross	26,236
Accumulated depreciation	$ 4,147
Depreciation life	35 years
Rentable square feet | ft²	76,031
Office Building [Member] | 1800 Owens St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 95,388
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	428,066
Land and improvements, gross	95,388
Buildings and improvements, gross	428,066
Land and improvements and buildings and improvements, gross	523,454
Accumulated depreciation	$ 4,467
Depreciation life	35 years
Rentable square feet | ft²	0
Office Building [Member] | 601 108th Ave., Bellevue, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	214,095
Costs capitalized subsequent to acquisition/ improvement	38,536
Land and improvements, gross	0
Buildings and improvements, gross	252,631
Land and improvements and buildings and improvements, gross	252,631
Accumulated depreciation	$ 79,397
Depreciation life	35 years
Rentable square feet | ft²	488,470
Office Building [Member] | 10900 NE 4th St., Bellevue, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 25,080
Initial cost, buildings and Improvements	150,877
Costs capitalized subsequent to acquisition/ improvement	40,547
Land and improvements, gross	25,080
Buildings and improvements, gross	191,424
Land and improvements and buildings and improvements, gross	216,504
Accumulated depreciation	$ 54,159
Depreciation life	35 years
Rentable square feet | ft²	428,557
Office Building [Member] | 837 N. 34th St., Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	37,404
Costs capitalized subsequent to acquisition/ improvement	4,950
Land and improvements, gross	0
Buildings and improvements, gross	42,354
Land and improvements and buildings and improvements, gross	42,354
Accumulated depreciation	$ 11,132
Depreciation life	35 years
Rentable square feet | ft²	112,487
Office Building [Member] | 701 N. 34th St., Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	48,027
Costs capitalized subsequent to acquisition/ improvement	8,226
Land and improvements, gross	0
Buildings and improvements, gross	56,253
Land and improvements and buildings and improvements, gross	56,253
Accumulated depreciation	$ 15,982
Depreciation life	35 years
Rentable square feet | ft²	141,860
Office Building [Member] | 801 N. 34th St., Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 0
Initial cost, buildings and Improvements	58,537
Costs capitalized subsequent to acquisition/ improvement	17,222
Land and improvements, gross	0
Buildings and improvements, gross	75,759
Land and improvements and buildings and improvements, gross	75,759
Accumulated depreciation	$ 16,318
Depreciation life	35 years
Rentable square feet | ft²	169,412
Office Building [Member] | 320 Westlake Avenue North, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances	$ 89,502
Initial cost, land and improvements	14,710
Initial cost, buildings and Improvements	82,018
Costs capitalized subsequent to acquisition/ improvement	14,378
Land and improvements, gross	14,710
Buildings and improvements, gross	96,396
Land and improvements and buildings and improvements, gross	111,106
Accumulated depreciation	$ 19,817
Depreciation life	35 years
Rentable square feet | ft²	184,644
Office Building [Member] | 321 Terry Avenue North, Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 10,430
Initial cost, buildings and Improvements	60,003
Costs capitalized subsequent to acquisition/ improvement	10,321
Land and improvements, gross	10,430
Buildings and improvements, gross	70,324
Land and improvements and buildings and improvements, gross	80,754
Accumulated depreciation	$ 15,561
Depreciation life	35 years
Rentable square feet | ft²	135,755
Office Building [Member] | 401 Terry Avenue North, Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, land and improvements	$ 22,500
Initial cost, buildings and Improvements	77,046
Costs capitalized subsequent to acquisition/ improvement	13
Land and improvements, gross	22,500
Buildings and improvements, gross	77,059
Land and improvements and buildings and improvements, gross	99,559
Accumulated depreciation	$ 15,556
Depreciation life	35 years
Rentable square feet | ft²	140,605
Undeveloped land and construction in progress [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances	$ 0
Initial cost, land and improvements	1,058,176
Initial cost, buildings and Improvements	0
Costs capitalized subsequent to acquisition/ improvement	1,237,954
Land and improvements, gross	1,058,176
Buildings and improvements, gross	1,237,954
Land and improvements and buildings and improvements, gross	2,296,130
Accumulated depreciation	$ 0
Rentable square feet | ft²	0

Schedule III - Real Estate an_3

Schedule III - Real Estate and Accumulated Depreciation - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)ft²projectproperty_unitsproperty_unit
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances | $	$ 259,502
Rentable square feet	13,475,795
Investment in real estate, federal Income tax basis | $	$ 7,900,000
Investment in real estate, held in VIE | $	$ 200,000
In-process development projects - under construction [Member]
Real Estate and Accumulated Depreciation [Line Items]
Rentable square feet	2,291,000
Number of buildings | project	6
Office Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances | $	$ 259,502
Rentable square feet	13,475,795
Unamortized debt issuance expense | $	$ (900)
Office Building [Member] | 1550 N. El Centro Avenue, Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Number of building units | property_units	200
Rentable square feet	0
Office Building [Member] | W. Olympic Blvd., Los Angeles, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances | $	$ 170,000
Office Building [Member] | 320 Westlake Ave. North, WA and 321 Terry Avenue North, Lake Union, WA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Initial cost, encumbrances | $	$ 89,500
Office Building [Member] | 3745 Paseo Place, Del Mar, CA (Retail) [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Rentable square feet	0
Office Building [Member] | 3200 Paseo Village Way, San Diego, CA (Resi Phase I) (16) [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Rentable square feet	0
Number of buildings | property_unit	237
Office Building [Member] | 1800 Owens St., San Francisco, CA [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Rentable square feet	0
Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Depreciation life	35 years
Tenant Improvements [Member] | Minimum [Member]
Real Estate and Accumulated Depreciation [Line Items]
Property depreciable lives	1 year
Tenant Improvements [Member] | Maximum [Member]
Real Estate and Accumulated Depreciation [Line Items]
Property depreciable lives	20 years
Retail site [Member] | 3745 Paseo Place, Del Mar, CA (Retail) [Member] | In-process development projects - under construction [Member]
Real Estate and Accumulated Depreciation [Line Items]
Rentable square feet	96,000
Retail site [Member] | 1800 Owens St., San Francisco, CA [Member] | In-process development projects - under construction [Member]
Real Estate and Accumulated Depreciation [Line Items]
Rentable square feet	750,000

Schedule III - Real Estate an_4

Schedule III - Real Estate and Accumulated Depreciation - Historical Cost Real Estate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Total real estate held for investment, beginning of year	$ 8,426,632	$ 7,417,777	$ 7,060,754
Acquisitions	460,512	581,671	19,829
Improvements, etc.	890,654	724,016	533,939
Total additions during period	1,351,166	1,305,687	553,768
Cost of real estate sold	(120,788)	(286,623)	(191,610)
Other	(28,237)	(10,209)	(5,135)
Total deductions during period	(149,025)	(296,832)	(196,745)
Total real estate held for investment, end of year	$ 9,628,773	$ 8,426,632	$ 7,417,777

Schedule III - Real Estate an_5

Schedule III - Real Estate and Accumulated Depreciation - Accumulated Depreciation Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Accumulated depreciation, beginning of year	$ 1,391,368	$ 1,264,162	$ 1,139,853
Depreciation of real estate	211,893	198,578	190,515
Total additions during period	211,893	198,578	190,515
Write-offs due to sale	(41,655)	(71,372)	(66,206)
Properties held for sale	0	0	0
Other	(245)	0	0
Total deductions during period	(41,900)	(71,372)	(66,206)
Accumulated depreciation, end of year	$ 1,561,361	$ 1,391,368	$ 1,264,162

Uncategorized Items - a123119kr

Label	Element	Value
Accounting Standards Update 2016-02 [Member] | Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (3,146,000)