Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 131,159	$ 216,312
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	164,594	165,797
Amortization of right of use assets - operating leases	605	0
Impairment loss	24,038	0
Non-cash compensation expense	15,050	14,772
Income from unconsolidated joint ventures	(213)	(461)
Distributions of net cash flow from operations of unconsolidated joint ventures	2,650	847
(Gains) losses from investments in securities	(2,969)	126
Non-cash portion of interest expense	5,447	5,299
Losses (gains) on sales of real estate	905	(96,397)
Change in assets and liabilities:
Tenant and other receivables, net	(14,000)	22,790
Note receivable	(125)	0
Accrued rental income, net	(15,570)	(26,319)
Prepaid expenses and other assets	(68,554)	(66,968)
Lease liabilities - operating leases	370	0
Accounts payable and accrued expenses	258	(13,913)
Accrued interest payable	(160)	12,399
Other liabilities	(17,831)	23,089
Tenant leasing costs	(18,420)	(31,595)
Total adjustments	76,075	9,466
Net cash provided by operating activities	207,234	225,778
Cash flows from investing activities:
Acquisitions of real estate	(43,061)	0
Construction in progress	(85,632)	(150,060)
Building and other capital improvements	(32,719)	(53,550)
Tenant improvements	(54,242)	(47,157)
Proceeds from sales of real estate	20,019	116,120
Capital contributions to unconsolidated joint ventures	(26,995)	(48,823)
Investments in securities, net	(885)	(318)
Net cash used in investing activities	(223,515)	(183,788)
Cash flows from financing activities:
Repayments of mortgage notes payable	(5,645)	(5,333)
Borrowings on unsecured line of credit	50,000	260,000
Repayments of unsecured line of credit	(50,000)	(190,000)
Payments on finance lease obligations	(470)	0
Payments on capital lease obligations	0	(3)
Payments on real estate financing transactions	0	(444)
Deferred financing costs	(186)	(16)
Net proceeds from equity transactions	1,792	(723)
Dividends and distributions	(166,362)	(140,288)
Contributions from noncontrolling interests in property partnerships	4,387	15,267
Distributions to noncontrolling interests in property partnerships	(24,128)	(30,690)
Net cash used in financing activities	(190,612)	(92,230)
Net decrease in cash and cash equivalents and cash held in escrows	(206,893)	(50,240)
Cash and cash equivalents and cash held in escrows, beginning of period	639,191	505,369
Cash and cash equivalents and cash held in escrows, end of period	432,298	455,129
Reconciliation of cash and cash equivalents and cash held in escrows:
Cash and cash equivalents, beginning of period	543,359	434,767
Cash held in escrows, beginning of period	95,832	70,602
Cash and Cash Equivalents, end of period	360,091	294,571
Cash held in escrows, end of period	72,207	160,558
Supplemental disclosures:
Cash paid for interest	107,094	89,412
Interest capitalized	11,813	17,378
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(31,640)	(29,609)
Additions to real estate included in accounts payable and accrued expenses	49,689	35,245
Real estate acquired through finance lease	122,563	0
Dividends and distributions declared but not paid	165,352	139,218
Conversions of noncontrolling interests to stockholders’ equity / partners' capital	492	832
Issuance of restricted securities to employees	37,428	36,433
Boston Properties Limited Partnership
Cash flows from operating activities:
Net income	134,837	220,766
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	162,682	163,853
Amortization of right of use assets - operating leases	605	0
Impairment loss	22,272	0
Non-cash compensation expense	15,050	14,772
Income from unconsolidated joint ventures	(213)	(461)
Distributions of net cash flow from operations of unconsolidated joint ventures	2,650	847
(Gains) losses from investments in securities	(2,969)	126
Non-cash portion of interest expense	5,447	5,299
Losses (gains) on sales of real estate	905	(98,907)
Change in assets and liabilities:
Tenant and other receivables, net	(14,000)	22,790
Note receivable	(125)	0
Accrued rental income, net	(15,570)	(26,319)
Prepaid expenses and other assets	(68,554)	(66,968)
Lease liabilities - operating leases	370	0
Accounts payable and accrued expenses	258	(13,913)
Accrued interest payable	(160)	12,399
Other liabilities	(17,831)	23,089
Tenant leasing costs	(18,420)	(31,595)
Total adjustments	72,397	5,012
Net cash provided by operating activities	207,234	225,778
Cash flows from investing activities:
Acquisitions of real estate	(43,061)	0
Construction in progress	(85,632)	(150,060)
Building and other capital improvements	(32,719)	(53,550)
Tenant improvements	(54,242)	(47,157)
Proceeds from sales of real estate	20,019	116,120
Capital contributions to unconsolidated joint ventures	(26,995)	(48,823)
Investments in securities, net	(885)	(318)
Net cash used in investing activities	(223,515)	(183,788)
Cash flows from financing activities:
Repayments of mortgage notes payable	(5,645)	(5,333)
Borrowings on unsecured line of credit	50,000	260,000
Repayments of unsecured line of credit	(50,000)	(190,000)
Payments on finance lease obligations	(470)	0
Payments on capital lease obligations	0	(3)
Payments on real estate financing transactions	0	(444)
Deferred financing costs	(186)	(16)
Net proceeds from equity transactions	1,792	(723)
Dividends and distributions	(166,362)	(140,288)
Contributions from noncontrolling interests in property partnerships	4,387	15,267
Distributions to noncontrolling interests in property partnerships	(24,128)	(30,690)
Net cash used in financing activities	(190,612)	(92,230)
Net decrease in cash and cash equivalents and cash held in escrows	(206,893)	(50,240)
Cash and cash equivalents and cash held in escrows, beginning of period	639,191	505,369
Cash and cash equivalents and cash held in escrows, end of period	432,298	455,129
Reconciliation of cash and cash equivalents and cash held in escrows:
Cash and cash equivalents, beginning of period	543,359	434,767
Cash held in escrows, beginning of period	95,832	70,602
Cash and Cash Equivalents, end of period	360,091	294,571
Cash held in escrows, end of period	72,207	160,558
Supplemental disclosures:
Cash paid for interest	107,094	89,412
Interest capitalized	11,813	17,378
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(31,640)	(29,609)
Additions to real estate included in accounts payable and accrued expenses	49,689	35,245
Real estate acquired through finance lease	122,563	0
Dividends and distributions declared but not paid	165,352	139,218
Conversions of noncontrolling interests to stockholders’ equity / partners' capital	492	832
Issuance of restricted securities to employees	$ 37,428	$ 36,433