Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Net income	$ 875,726	$ 334,620
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	349,282	342,005
Amortization of right of use assets - operating leases	1,128	1,213
Impairment loss	0	24,038
Non-cash compensation expense	27,899	25,444
Income from unconsolidated joint ventures	(1,463)	(48,177)
Distributions of net cash flow from operations of unconsolidated joint ventures	13,382	3,890
Losses (gains) from investments in securities	893	(4,134)
Allowance for current expected credit losses	484	0
Non-cash portion of interest expense	11,483	10,900
Gains on sales of real estate	(613,932)	(781)
Change in assets and liabilities:
Tenant and other receivables, net	18,516	(11,514)
Notes receivable, net	(258)	(250)
Accrued rental income, net	(43,399)	(37,473)
Prepaid expenses and other assets	(12,057)	(9,319)
Lease liabilities - operating leases	799	780
Accounts payable and accrued expenses	(20,493)	17,458
Accrued interest payable	5,262	(78)
Other liabilities	(21,912)	(30,503)
Tenant leasing costs	(37,068)	(52,515)
Total adjustments	(321,454)	230,984
Net cash provided by operating activities	554,272	565,604
Cash flows from investing activities:
Acquisitions of real estate	(133,406)	(43,061)
Construction in progress	(247,615)	(203,259)
Building and other capital improvements	(68,386)	(79,943)
Tenant improvements	(118,903)	(115,940)
Proceeds from sales of real estate	506,337	60,398
Capital contributions to unconsolidated joint ventures	(106,168)	(50,068)
Capital distributions from unconsolidated joint ventures	54,413	105,000
Issuance of notes receivable, net	(9,800)	0
Investments in securities, net	3,006	(1,079)
Net cash used in investing activities	(120,522)	(327,952)
Cash flows from financing activities:
Repayments of mortgage notes payable	(8,477)	(9,702)
Proceeds from unsecured senior notes	1,248,125	848,428
Borrowings on unsecured line of credit	265,000	380,000
Repayments of unsecured line of credit	(265,000)	(380,000)
Payments on finance lease obligations	0	(628)
Deferred financing costs	(9,465)	(7,112)
Net proceeds from equity transactions	3,183	2,261
Dividends and distributions	(344,239)	(332,961)
Contributions from noncontrolling interests in property partnerships	5,957	12,148
Distributions to noncontrolling interests in property partnerships	(29,065)	(39,401)
Acquisition of noncontrolling interest in property partnership	0	(186,952)
Net cash provided by financing activities	866,019	286,081
Net increase (decrease) in cash and cash equivalents and cash held in escrows	1,299,769	523,733
Cash and cash equivalents and cash held in escrows, beginning of period	691,886	639,191
Cash and cash equivalents and cash held in escrows, end of period	1,991,655	1,162,924
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	644,950	543,359
Cash held in escrows, beginning of period	46,936	95,832
Cash and cash equivalents, end of period	1,691,047	1,087,001
Cash held in escrows,end of period	300,608	75,923
Supplemental disclosures:
Cash paid for interest	213,754	216,754
Interest capitalized	27,866	25,069
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(50,141)	(61,283)
Change in real estate included in accounts payable and accrued expenses	(25,461)	115,150
Real estate acquired through finance lease	0	122,563
Accrued rental income, net deconsolidated	(4,558)	0
Tenant leasing costs, net deconsolidated	(3,462)	0
Building and other capital improvements, net deconsolidated	(111,889)	0
Tenant improvements, net deconsolidated	(12,331)	0
Investment in unconsolidated joint venture recorded upon deconsolidation	347,898	0
Dividends and distributions declared but not paid	171,077	165,419
Conversions of noncontrolling interests to stockholders’ equity	26,344	1,212
Issuance of restricted securities to employees and non-employee directors	43,462	38,923
Boston Properties Limited Partnership
Net income	892,277	340,659
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	345,694	337,881
Amortization of right of use assets - operating leases	1,128	1,213
Impairment loss	0	22,272
Non-cash compensation expense	27,899	25,444
Income from unconsolidated joint ventures	(1,463)	(48,177)
Distributions of net cash flow from operations of unconsolidated joint ventures	13,382	3,890
Losses (gains) from investments in securities	893	(4,134)
Allowance for current expected credit losses	484	0
Non-cash portion of interest expense	11,483	10,900
Gains on sales of real estate	(626,895)	(930)
Change in assets and liabilities:
Tenant and other receivables, net	18,516	(11,514)
Notes receivable, net	(258)	(250)
Accrued rental income, net	(43,399)	(37,473)
Prepaid expenses and other assets	(12,057)	(9,319)
Lease liabilities - operating leases	799	780
Accounts payable and accrued expenses	(20,493)	17,458
Accrued interest payable	5,262	(78)
Other liabilities	(21,912)	(30,503)
Tenant leasing costs	(37,068)	(52,515)
Total adjustments	(338,005)	224,945
Net cash provided by operating activities	554,272	565,604
Cash flows from investing activities:
Acquisitions of real estate	(133,406)	(43,061)
Construction in progress	(247,615)	(203,259)
Building and other capital improvements	(68,386)	(79,943)
Tenant improvements	(118,903)	(115,940)
Proceeds from sales of real estate	506,337	60,398
Capital contributions to unconsolidated joint ventures	(106,168)	(50,068)
Capital distributions from unconsolidated joint ventures	54,413	105,000
Issuance of notes receivable, net	(9,800)	0
Investments in securities, net	3,006	(1,079)
Net cash used in investing activities	(120,522)	(327,952)
Cash flows from financing activities:
Repayments of mortgage notes payable	(8,477)	(9,702)
Proceeds from unsecured senior notes	1,248,125	848,428
Borrowings on unsecured line of credit	265,000	380,000
Repayments of unsecured line of credit	(265,000)	(380,000)
Payments on finance lease obligations	0	(628)
Deferred financing costs	(9,465)	(7,112)
Net proceeds from equity transactions	3,183	2,261
Dividends and distributions	(344,239)	(332,961)
Contributions from noncontrolling interests in property partnerships	5,957	12,148
Distributions to noncontrolling interests in property partnerships	(29,065)	(39,401)
Acquisition of noncontrolling interest in property partnership	0	(186,952)
Net cash provided by financing activities	866,019	286,081
Net increase (decrease) in cash and cash equivalents and cash held in escrows	1,299,769	523,733
Cash and cash equivalents and cash held in escrows, beginning of period	691,886	639,191
Cash and cash equivalents and cash held in escrows, end of period	1,991,655	1,162,924
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	644,950	543,359
Cash held in escrows, beginning of period	46,936	95,832
Cash and cash equivalents, end of period	1,691,047	1,087,001
Cash held in escrows,end of period	300,608	75,923
Supplemental disclosures:
Cash paid for interest	213,754	216,754
Interest capitalized	27,866	25,069
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(50,141)	(61,283)
Change in real estate included in accounts payable and accrued expenses	(25,461)	115,150
Real estate acquired through finance lease	0	122,563
Accrued rental income, net deconsolidated	(4,558)	0
Tenant leasing costs, net deconsolidated	(3,462)	0
Building and other capital improvements, net deconsolidated	(111,889)	0
Tenant improvements, net deconsolidated	(12,331)	0
Investment in unconsolidated joint venture recorded upon deconsolidation	347,898	0
Dividends and distributions declared but not paid	171,077	165,419
Conversions of noncontrolling interests to stockholders’ equity	26,344	1,212
Issuance Of Restricted Units To Employees And Directors	$ 43,462	$ 38,923