Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 562,481	$ 569,977	$ 799,918
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	617,547	694,403	639,542
Impairment loss	0	1,783	0
Non-cash compensation expense	35,361	32,911	29,183
Income from unconsolidated joint ventures	(11,232)	(8,074)	(22,770)
Gain on sale of investment in unconsolidated joint venture	0	(59,370)	0
Distributions of net cash flow from operations of unconsolidated joint ventures	26,858	24,955	8,469
(Gains) losses on investments in securities	(3,678)	(2,273)	653
Non-cash portion of interest expense	(1,284)	(35,052)	(42,271)
Settlement of accreted debt discount on redemption of unsecured senior notes	(1,980)	0	0
(Gains) losses from early extinguishments of debt	(13,280)	371	21,837
Gains on sales of real estate	(7,663)	(80,606)	(375,895)
Change in assets and liabilities:
Cash held in escrows	8,194	2,277	(18,284)
Tenant and other receivables, net	2,433	3,688	(46,326)
Accrued rental income, net	(58,355)	(28,127)	(73,911)
Prepaid expenses and other assets	51,425	52,923	(16,877)
Accounts payable and accrued expenses	10,482	15,666	(6,310)
Accrued interest payable	(160,521)	53,547	26,854
Other liabilities	(44,914)	(106,022)	(34,005)
Tenant leasing costs	(104,429)	(96,103)	(90,396)
Total adjustments	344,964	466,897	(507)
Net cash provided by operating activities	907,445	1,036,874	799,411
Cash flows from investing activities:
Acquisitions of real estate	(15,953)	(78,000)	0
Construction in progress	(608,404)	(500,350)	(374,664)
Building and other capital improvements	(222,482)	(150,640)	(112,755)
Tenant improvements	(205,331)	(230,298)	(144,572)
Proceeds from sales of real estate	29,810	122,750	602,600
Proceeds from sales of real estate placed in escrow	(29,810)	(122,647)	(200,612)
Proceeds from sales of real estate released from escrow	29,810	122,647	634,165
Cash placed in escrow for land sale contracts	0	0	(7,111)
Cash released from escrow for land sale contracts	0	1,596	5,312
Cash released from escrow for investing activities	9,230	6,694	0
Cash placed in escrow for investment in unconsolidated joint venture	(25,000)	0	0
Capital contributions to unconsolidated joint ventures	(109,015)	(575,795)	(38,207)
Capital distributions from unconsolidated joint ventures	251,000	20,440	24,527
Proceeds from sale of investment in unconsolidated joint venture	0	55,707	0
Investments in marketable securities	0	0	(667,335)
Investments in securities, net	(1,669)	(1,161)	(1,574)
Net cash used in investing activities	(897,814)	(1,329,057)	(280,226)
Cash flows from financing activities:
Proceeds from mortgage notes payable	2,300,000	0	0
Repayments of mortgage notes payable	(1,317,653)	(1,326,865)	(54,801)
Proceeds from unsecured senior notes	847,935	1,989,790	0
Redemption of unsecured senior notes	(848,020)	0	0
Borrowings on unsecured line of credit	580,000	25,000	0
Repayments of unsecured line of credit	(535,000)	(25,000)	0
Repayments of mezzanine notes payable	(306,000)	0	0
Repayments of outside members’ notes payable	(70,424)	0	0
Payments on capital lease obligations	(401)	(745)	(356)
Proceeds from real estate financing transaction	0	0	6,000
Payments on real estate financing transactions	(2,840)	(5,260)	(3,103)
Deposit on mortgage note payable interest rate lock	(23,200)	0	0
Return of deposit on mortgage note payable interest rate lock	23,200	0	0
Deferred financing costs	(50,705)	(16,121)	(1,510)
Net proceeds from equity transactions	241	(271)	799
Redemption of preferred units	0	0	(633)
Dividends and distributions	(526,578)	(671,626)	(1,226,199)
Contributions from noncontrolling interests in property partnerships	52,009	11,951	2,705
Acquisition of noncontrolling interest in property partnership	0	0	(108,499)
Distributions to noncontrolling interests in property partnerships	(54,342)	(55,474)	(172,949)
Net cash provided by (used in) financing activities	68,222	(74,621)	(1,558,546)
Net increase (decrease) in cash and cash equivalents	77,853	(366,804)	(1,039,361)
Cash and cash equivalents, beginning of year	356,914	723,718	1,763,079
Cash and cash equivalents, end of year	434,767	356,914	723,718
Supplemental disclosures:
Cash paid for interest	598,486	433,591	481,826
Interest capitalized	61,070	39,237	34,213
Non-cash investing and financing activities:
Write off of fully depreciated real estate	(124,891)	(206,721)	(45,455)
Change in real estate included in accounts payable and accrued expenses	27,978	(1,481)	74,985
Real estate acquired through capital lease	28,962	21,000	0
Outside members’ notes payable contributed to noncontrolling interests in property partnerships	109,576	0	0
Marketable securities transferred in connection with the legal defeasance of mortgage note payable	0	0	667,335
Mortgage note payable legally defeased	0	0	640,500
Mortgage note payable assigned in connection with the sale of real estate	0	0	116,993
Dividends and distributions declared but not paid	139,040	130,308	327,320
Conversions of noncontrolling interests to stockholders’ equity	16,916	6,461	14,343
Issuance of restricted securities to employees and directors	35,989	33,615	43,355
Boston Properties Limited Partnership
Net income	571,198	583,773	809,109
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	609,407	682,776	631,549
Impairment loss	0	1,783	0
Non-cash compensation expense	35,361	32,911	29,183
Income from unconsolidated joint ventures	(11,232)	(8,074)	(22,770)
Gain on sale of investment in unconsolidated joint venture	0	(59,370)	0
Distributions of net cash flow from operations of unconsolidated joint ventures	26,858	24,955	8,469
(Gains) losses on investments in securities	(3,678)	(2,273)	653
Non-cash portion of interest expense	(1,284)	(35,052)	(42,271)
Settlement of accreted debt discount on redemption of unsecured senior notes	(1,980)	0	0
(Gains) losses from early extinguishments of debt	(13,280)	371	21,837
Gains on sales of real estate	(8,240)	(82,775)	(377,093)
Change in assets and liabilities:
Cash held in escrows	8,194	2,277	(18,284)
Tenant and other receivables, net	2,433	3,688	(46,326)
Accrued rental income, net	(58,355)	(28,127)	(73,911)
Prepaid expenses and other assets	51,425	52,923	(16,877)
Accounts payable and accrued expenses	10,482	15,666	(6,310)
Accrued interest payable	(160,521)	53,547	26,854
Other liabilities	(44,914)	(106,022)	(34,005)
Tenant leasing costs	(104,429)	(96,103)	(90,396)
Total adjustments	336,247	453,101	(9,698)
Net cash provided by operating activities	907,445	1,036,874	799,411
Cash flows from investing activities:
Acquisitions of real estate	(15,953)	(78,000)	0
Construction in progress	(608,404)	(500,350)	(374,664)
Building and other capital improvements	(222,482)	(150,640)	(112,755)
Tenant improvements	(205,331)	(230,298)	(144,572)
Proceeds from sales of real estate	29,810	122,750	602,600
Proceeds from sales of real estate placed in escrow	(29,810)	(122,647)	(200,612)
Proceeds from sales of real estate released from escrow	29,810	122,647	634,165
Cash placed in escrow for land sale contracts	0	0	(7,111)
Cash released from escrow for land sale contracts	0	1,596	5,312
Cash released from escrow for investing activities	9,230	6,694	0
Cash placed in escrow for investment in unconsolidated joint venture	(25,000)	0	0
Capital contributions to unconsolidated joint ventures	(109,015)	(575,795)	(38,207)
Capital distributions from unconsolidated joint ventures	251,000	20,440	24,527
Proceeds from sale of investment in unconsolidated joint venture	0	55,707	0
Investments in marketable securities	0	0	(667,335)
Investments in securities, net	(1,669)	(1,161)	(1,574)
Net cash used in investing activities	(897,814)	(1,329,057)	(280,226)
Cash flows from financing activities:
Proceeds from mortgage notes payable	2,300,000	0	0
Repayments of mortgage notes payable	(1,317,653)	(1,326,865)	(54,801)
Proceeds from unsecured senior notes	847,935	1,989,790	0
Redemption of unsecured senior notes	(848,020)	0	0
Borrowings on unsecured line of credit	580,000	25,000	0
Repayments of unsecured line of credit	(535,000)	(25,000)	0
Repayments of mezzanine notes payable	(306,000)	0	0
Repayments of outside members’ notes payable	(70,424)	0	0
Payments on capital lease obligations	(401)	(745)	(356)
Proceeds from real estate financing transaction	0	0	6,000
Payments on real estate financing transactions	(2,840)	(5,260)	(3,103)
Deposit on mortgage note payable interest rate lock	(23,200)	0	0
Return of deposit on mortgage note payable interest rate lock	23,200	0	0
Deferred financing costs	(50,705)	(16,121)	(1,510)
Net proceeds from equity transactions	241	(271)	799
Redemption of preferred units	0	0	(633)
Dividends and distributions	(526,578)	(671,626)	(1,226,199)
Contributions from noncontrolling interests in property partnerships	52,009	11,951	2,705
Acquisition of noncontrolling interest in property partnership	0	0	(108,499)
Distributions to noncontrolling interests in property partnerships	(54,342)	(55,474)	(172,949)
Net cash provided by (used in) financing activities	68,222	(74,621)	(1,558,546)
Net increase (decrease) in cash and cash equivalents	77,853	(366,804)	(1,039,361)
Cash and cash equivalents, beginning of year	356,914	723,718	1,763,079
Cash and cash equivalents, end of year	434,767	356,914	723,718
Supplemental disclosures:
Cash paid for interest	598,486	433,591	481,826
Interest capitalized	61,070	39,237	34,213
Non-cash investing and financing activities:
Write off of fully depreciated real estate	(123,714)	(202,388)	(45,455)
Change in real estate included in accounts payable and accrued expenses	27,978	(1,481)	74,985
Real estate acquired through capital lease	28,962	21,000	0
Outside members’ notes payable contributed to noncontrolling interests in property partnerships	109,576	0	0
Marketable securities transferred in connection with the legal defeasance of mortgage note payable	0	0	667,335
Mortgage note payable legally defeased	0	0	640,500
Mortgage note payable assigned in connection with the sale of real estate	0	0	116,993
Dividends and distributions declared but not paid	139,040	130,308	327,320
Conversions of noncontrolling interests to stockholders’ equity	16,916	6,461	14,343
Issuance of restricted securities to employees and directors	$ 35,989	$ 33,615	$ 43,355