CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 507,411	$ 45,418
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of real estate assets and leasing costs	74,431	72,438
Depreciation of non-real estate furniture, fixtures and equipment	1,501	1,932
Revenue reversals for doubtful accounts (Note 9)	1,035	6,487
Non-cash amortization of share-based compensation awards	7,877	6,783
Non-cash amortization of deferred financing costs and debt discounts and premiums	794	505
Non-cash amortization of net below market rents	(1,181)	(2,586)
Gain on sale of depreciable operating properties (Note 2)	(457,288)	0
Non-cash amortization of deferred revenue related to tenant-funded tenant improvements	(4,204)	(4,420)
Straight-line rents	(17,292)	(19,995)
Amortization of right of use ground lease assets	211	203
Net change in other operating assets	1,710	7,966
Net change in other operating liabilities	29,147	8,209
Net cash provided by operating activities	144,152	122,940
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for development properties and undeveloped land	(172,325)	(167,328)
Expenditures for operating properties and other capital assets	(28,242)	(44,084)
Net proceeds received from dispositions (Note 2)	1,012,817	0
Net cash provided by (used in) investing activities	812,250	(211,412)
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments and repayments of secured debt	(1,316)	(1,266)
Financing costs	(235)	(160)
Repurchase of common stock and restricted stock units	(21,137)	(9,799)
Distributions to noncontrolling interests in consolidated property partnerships	(11,672)	(2,608)
Dividends and distributions paid to common stockholders and common unitholders	(58,594)	(52,399)
Net proceeds from issuance of common stock	0	721,794
Borrowings on unsecured revolving credit facility	0	190,000
Repayments on unsecured revolving credit facility	0	(55,000)
Net cash (used in) provided by financing activities	(92,954)	790,562
Net increase in cash and cash equivalents and restricted cash	863,448	702,090
Cash and cash equivalents and restricted cash, beginning of period	823,130	76,344
Cash and cash equivalents and restricted cash, end of period	1,686,578	778,434
Kilroy Realty L.P. [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	507,411	45,418
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of real estate assets and leasing costs	74,431	72,438
Depreciation of non-real estate furniture, fixtures and equipment	1,501	1,932
Revenue reversals for doubtful accounts (Note 9)	1,035	6,487
Non-cash amortization of share-based compensation awards	7,877	6,783
Non-cash amortization of deferred financing costs and debt discounts and premiums	794	505
Non-cash amortization of net below market rents	(1,181)	(2,586)
Gain on sale of depreciable operating properties (Note 2)	(457,288)	0
Non-cash amortization of deferred revenue related to tenant-funded tenant improvements	(4,204)	(4,420)
Straight-line rents	(17,292)	(19,995)
Amortization of right of use ground lease assets	211	203
Net change in other operating assets	1,710	7,966
Net change in other operating liabilities	29,147	8,209
Net cash provided by operating activities	144,152	122,940
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for development properties and undeveloped land	(172,325)	(167,328)
Expenditures for operating properties and other capital assets	(28,242)	(44,084)
Net proceeds received from dispositions (Note 2)	1,012,817	0
Net cash provided by (used in) investing activities	812,250	(211,412)
CASH FLOWS FROM FINANCING ACTIVITIES:
Principal payments and repayments of secured debt	(1,316)	(1,266)
Financing costs	(235)	(160)
Repurchase of common stock and restricted stock units	(21,137)	(9,799)
Distributions to noncontrolling interests in consolidated property partnerships	(11,672)	(2,608)
Dividends and distributions paid to common stockholders and common unitholders	(58,594)	(52,399)
Net proceeds from issuance of common stock	0	721,794
Borrowings on unsecured revolving credit facility	0	190,000
Repayments on unsecured revolving credit facility	0	(55,000)
Net cash (used in) provided by financing activities	(92,954)	790,562
Net increase in cash and cash equivalents and restricted cash	863,448	702,090
Cash and cash equivalents and restricted cash, beginning of period	823,130	76,344
Cash and cash equivalents and restricted cash, end of period	$ 1,686,578	$ 778,434