Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 376,877	$ 282,574
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	322,214	311,124
Non-cash compensation expense	23,243	19,237
Income from unconsolidated joint ventures	(1,230)	(6,192)
Distributions of net cash flow from operations of unconsolidated joint ventures	1,663	2,905
Gains from investments in securities	(379)	(1,772)
Gains from early extinguishments of debt	0	(14,354)
Non-cash portion of interest expense	10,607	(11,979)
Gains on sales of real estate	(114,689)	(3,900)
Change in assets and liabilities:
Tenant and other receivables, net	33,012	2,033
Accrued rental income, net	(45,759)	(19,348)
Prepaid expenses and other assets	(4,641)	36,223
Accounts payable and accrued expenses	(9,899)	(2,608)
Accrued interest payable	12,999	(158,761)
Other liabilities	11,571	(33,121)
Tenant leasing costs	(54,743)	(37,252)
Total adjustments	183,969	82,235
Net cash provided by operating activities	560,846	364,809
Cash flows from investing activities:
Acquisitions of real estate	0	(15,953)
Construction in progress	(380,565)	(297,747)
Building and other capital improvements	(96,730)	(100,808)
Tenant improvements	(83,982)	(107,533)
Proceeds from sales of real estate	141,249	17,049
Capital contributions to unconsolidated joint ventures	(65,250)	(41,491)
Investments in securities, net	(523)	(1,195)
Net cash used in investing activities	(485,801)	(547,678)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	2,300,000
Repayments of mortgage notes payable	(9,192)	(1,308,708)
Borrowings on unsecured line of credit	345,000	430,000
Repayments of unsecured line of credit	(390,000)	(430,000)
Proceeds from unsecured term loan	500,000	0
Repayments of mezzanine notes payable	0	(306,000)
Repayments of outside members’ notes payable	0	(70,424)
Payments on capital lease obligations	0	(548)
Payments on real estate financing transactions	(960)	(1,013)
Deposit on mortgage note payable interest rate lock	0	(23,200)
Return of deposit on mortgage note payable interest rate lock	0	23,200
Deferred financing costs	(263)	(43,635)
Debt prepayment and extinguishment costs	0	(90)
Net proceeds from equity transactions	(684)	(181)
Dividends and distributions	(280,754)	(263,221)
Contributions from noncontrolling interests in property partnerships	27,532	23,496
Distributions to noncontrolling interests in property partnerships	(44,033)	(27,115)
Net cash provided by financing activities	146,646	302,561
Net increase in cash and cash equivalents and cash held in escrows	221,691	119,692
Cash and cash equivalents and cash held in escrows, beginning of period	505,369	420,088
Cash and cash equivalents and cash held in escrows, end of period	727,060	539,780
Reconciliation of cash and cash equivalents and cash held in escrows:
Cash and cash equivalents, beginning of period	434,767	356,914
Cash held in escrows, beginning of period	70,602	63,174
Cash and Cash Equivalents, end of period	472,555	492,435
Cash held in escrows, end of period	254,505	47,345
Supplemental disclosures:
Cash paid for interest	192,898	388,045
Interest capitalized	34,999	26,628
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(78,900)	(86,135)
Additions to real estate included in accounts payable and accrued expenses	326	22,994
Real estate acquired through capital lease	0	28,962
Outside members’ notes payable contributed to noncontrolling interests in property partnerships	0	109,576
Dividends and distributions declared but not paid	139,263	130,432
Conversions of noncontrolling interests to stockholders’ equity / partners' capital	1,196	16,422
Issuance of restricted securities to employees	37,342	35,945
Boston Properties Limited Partnership
Cash flows from operating activities:
Net income	383,752	287,383
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	318,327	306,892
Non-cash compensation expense	23,243	19,237
Income from unconsolidated joint ventures	(1,230)	(6,192)
Distributions of net cash flow from operations of unconsolidated joint ventures	1,663	2,905
Gains from investments in securities	(379)	(1,772)
Gains from early extinguishments of debt	0	(14,354)
Non-cash portion of interest expense	10,607	(11,979)
Gains on sales of real estate	(117,677)	(4,477)
Change in assets and liabilities:
Tenant and other receivables, net	33,012	2,033
Accrued rental income, net	(45,759)	(19,348)
Prepaid expenses and other assets	(4,641)	36,223
Accounts payable and accrued expenses	(9,899)	(2,608)
Accrued interest payable	12,999	(158,761)
Other liabilities	11,571	(33,121)
Tenant leasing costs	(54,743)	(37,252)
Total adjustments	177,094	77,426
Net cash provided by operating activities	560,846	364,809
Cash flows from investing activities:
Acquisitions of real estate	0	(15,953)
Construction in progress	(380,565)	(297,747)
Building and other capital improvements	(96,730)	(100,808)
Tenant improvements	(83,982)	(107,533)
Proceeds from sales of real estate	141,249	17,049
Capital contributions to unconsolidated joint ventures	(65,250)	(41,491)
Investments in securities, net	(523)	(1,195)
Net cash used in investing activities	(485,801)	(547,678)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	2,300,000
Repayments of mortgage notes payable	(9,192)	(1,308,708)
Borrowings on unsecured line of credit	345,000	430,000
Repayments of unsecured line of credit	(390,000)	(430,000)
Proceeds from unsecured term loan	500,000	0
Repayments of mezzanine notes payable	0	(306,000)
Repayments of outside members’ notes payable	0	(70,424)
Payments on capital lease obligations	0	(548)
Payments on real estate financing transactions	(960)	(1,013)
Deposit on mortgage note payable interest rate lock	0	(23,200)
Return of deposit on mortgage note payable interest rate lock	0	23,200
Deferred financing costs	(263)	(43,635)
Debt prepayment and extinguishment costs	0	(90)
Net proceeds from equity transactions	(684)	(181)
Dividends and distributions	(280,754)	(263,221)
Contributions from noncontrolling interests in property partnerships	27,532	23,496
Distributions to noncontrolling interests in property partnerships	(44,033)	(27,115)
Net cash provided by financing activities	146,646	302,561
Net increase in cash and cash equivalents and cash held in escrows	221,691	119,692
Cash and cash equivalents and cash held in escrows, beginning of period	505,369	420,088
Cash and cash equivalents and cash held in escrows, end of period	727,060	539,780
Reconciliation of cash and cash equivalents and cash held in escrows:
Cash and cash equivalents, beginning of period	434,767	356,914
Cash held in escrows, beginning of period	70,602	63,174
Cash and Cash Equivalents, end of period	472,555	492,435
Cash held in escrows, end of period	254,505	47,345
Supplemental disclosures:
Cash paid for interest	192,898	388,045
Interest capitalized	34,999	26,628
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(78,900)	(85,525)
Additions to real estate included in accounts payable and accrued expenses	326	22,994
Real estate acquired through capital lease	0	28,962
Outside members’ notes payable contributed to noncontrolling interests in property partnerships	0	109,576
Dividends and distributions declared but not paid	139,263	130,432
Conversions of noncontrolling interests to stockholders’ equity / partners' capital	1,196	16,422
Issuance of restricted securities to employees	$ 37,342	$ 35,945