Boston Properties LTD Partnership 10-Q 8 Nov 13 2013 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Sep. 30, 2013	Nov. 04, 2013
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Entity Registrant Name	'BOSTON PROPERTIES LTD PARTNERSHIP	'
Amendment Flag	'false	'
Entity Central Index Key	'0001043121	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	0

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS	'	'
Real estate, at cost	$16,674,568	$13,146,993
Construction in progress	1,502,017	1,036,780
Land held for future development	295,370	271,189
Less: accumulated depreciation	-3,013,549	-2,876,983
Total real estate	15,458,406	11,577,979
Cash and cash equivalents	1,641,275	1,041,978
Cash held in escrows	53,499	55,181
Investments in securities	15,377	12,172
Tenant and other receivables (net of allowance for doubtful accounts of $1,515 and $1,960, respectively)	55,393	69,555
Related party notes receivable	0	282,491
Interest receivable from related party notes receivable	0	104,816
Accrued rental income (net of allowance of $3,382 and $1,571, respectively)	641,041	598,199
Deferred charges, net	918,798	588,235
Prepaid expenses and other assets	238,688	90,610
Investments in unconsolidated joint ventures	129,038	659,916
Total assets	19,151,515	15,081,132
Liabilities:	'	'
Mortgage notes payable	4,468,069	3,102,485
Unsecured senior notes (net of discount of $14,576 and $9,472, respectively)	5,835,424	4,639,528
Unsecured exchangeable senior notes (net of discount of $555 and $1,653, respectively)	739,536	1,170,356
Unsecured line of credit	0	0
Mezzanine notes payable	311,340	0
Related party notes payable	180,000	0
Accounts payable and accrued expenses	215,778	199,102
Distributions payable	112,470	110,488
Accrued interest payable	181,310	72,461
Other liabilities	567,464	324,613
Total liabilities	12,611,391	9,619,033
Commitments and contingencies	0	0
Noncontrolling interests:	'	'
Redeemable interest in property partnerships	98,649	97,558
Redeemable partnership units-995,997 series two preferred units outstanding (1,307,083 common units at redemption value, if converted) at September 30, 2013 and December 31, 2012, respectively	139,727	138,302
Redeemable partnership units - 360,126 and 1,221,527 series four preferred units outstanding at redemption value at September 30, 2013 and December 31, 2012	18,006	61,076
Redeemable partnership units-15,738,523 and 16,053,497 common units and 1,460,200 and 1,303,296 long term incentive units outstanding at redemption value at September 30, 2013 and December 31, 2012, respectively	1,838,543	1,836,522
Capital:	'	'
5.25% Series B cumulative redeemable preferred units, liquidation preference of $2,500 per unit, 80,000 and no units issued and outstanding at September 30, 2013 and December 31,2012, respectively	193,623	0
Boston Properties Limited Partnership partners' capital-1,695,893 and 1,689,580 general partner units and 150,694,702 and 149,911,629 limited partner units outstanding at September 30, 2013 and December 31, 2012, respectively	3,769,947	3,330,605
Noncontrolling interests in property partnerships	481,629	-1,964
Total capital	4,445,199	3,328,641
Total liabilities and capital	$19,151,515	$15,081,132

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Tenant and other receivables, allowance for doubtful accounts	$1,515	$1,960
Accrued rental income, allowance	3,382	1,571
Unsecured senior notes, discount	14,576	10,472
Unsecured exchangeable senior notes, discount	$555	$1,653
Redeemable partnership units, series two preferred units outstanding (in units)	995,997	995,997
Redeemable partnership units, common units at redemption value, if converted (in units)	1,307,083	1,307,083
Redeemable partnership units, series four preferred units outstanding (in units)	360,126	1,221,527
Redeemable partnership units, common units (in units)	15,738,523	16,053,497
Redeemable partnership units, long term incentive units outstanding at redemption value (in units)	1,460,200	1,303,296
General Partners' Capital Account, Units Outstanding (in units)	1,695,893	1,689,580
Limited Partners' Capital Account, Units Outstanding (in units)	150,694,702	149,911,629
Series B Cumulative Redeemable Preferred Stock [Member]	'	'
Series B Dividend Rate Percentage	5.25%	0.00%
Series B, Liquidation Preference Per Unit	$2,500	$0
Series B, Unitsssued	80,000	0
Series B, Units Outstanding	80,000	0

Consolidated_Statements_Of_Ope

Consolidated Statements Of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenue	'	'	'	'
Base rent	$451,866	$366,795	$1,228,429	$1,087,787
Recoveries from tenants	80,839	59,855	213,647	168,858
Parking and other	25,246	22,647	72,625	67,846
Total rental revenue	557,951	449,297	1,514,701	1,324,491
Hotel revenue	10,652	9,359	30,061	26,224
Development and management services	5,479	8,024	22,072	25,733
Total revenue	574,082	466,680	1,566,834	1,376,448
Expenses	'	'	'	'
Rental	200,350	165,693	547,212	477,249
Hotel	6,580	6,886	20,959	19,601
General and administrative	24,841	21,617	94,673	72,208
Transaction costs	766	1,140	1,744	3,252
Impairment loss	0	0	4,401	0
Depreciation and amortization	152,156	108,609	402,892	323,680
Total expenses	384,693	303,945	1,071,881	895,990
Operating income	189,389	162,735	494,953	480,458
Other income (expense)	'	'	'	'
Income from unconsolidated joint ventures	14,736	9,217	72,240	42,129
Gains on Consolidation of Joint Ventures	1,810	0	-385,991	0
Interest and other income	3,879	4,001	6,646	8,029
Gains (Losses) from investments in securities	956	587	1,872	1,202
Gains from early extinguishments of debt	-30	-5,494	122	-4,453
Interest expense	-122,173	-105,030	-325,746	-308,168
Income from continuing operations	84,947	66,016	636,078	219,197
Discontinued operations	'	'	'	'
Income from discontinued operations	1,078	1,550	5,597	5,596
Gains on sale of real estate from discontinued operations	88,565	0	88,565	38,445
Gain on forgiveness of debt from discontinued operations	0	0	20,736	0
Impairment loss from discontinued operations	0	0	-2,852	0
Net income	174,590	67,566	748,124	263,238
Net income attributable to noncontrolling interests	'	'	'	'
Noncontrolling interest in property partnerships	-3,279	458	-924	1,461
Noncontrolling interest-redeemable preferred units	-3,729	-874	-8,796	-2,440
Net income attributable to Boston Properties Limited Partnership	$174,140	$66,234	$740,252	$259,337
Basic earnings per common unit attributable to Boston Properties Limited Partnership	'	'	'	'
Income from continuing operations (in dollars per share)	$0.50	$0.38	$3.70	$1.29
Discontinued operations (in dollars per share)	$0.53	$0.01	$0.66	$0.26
Net income (in dollars per share)	$1.03	$0.39	$4.36	$1.55
Weighted average number of common units outstanding (in shares)	169,236	168,461	168,975	167,517
Diluted earnings per common unit attributable to Boston Properties Limited Partnership	'	'	'	'
Income from continuing operations (in dollars per share)	$0.50	$0.38	$3.69	$1.28
Discontinued operations (in dollars per share)	$0.52	$0.01	$0.66	$0.26
Diluted Earnings: Net income, Per Unit Amount (in dollars per share)	$1.02	$0.39	$4.35	$1.54
Weighted average number of common and common equivalent units outstanding (in shares)	169,521	169,643	169,356	168,172

Consolidated_Statements_Of_Com

Consolidated Statements Of Comprehensive Income (USD $)	3 Months Ended				9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Statement of Comprehensive Income [Abstract]	'		'		'		'
Net income	$174,590		$67,566		$748,124		$263,238
Other comprehensive income:	'		'		'		'
Amortization of interest rate contracts	629	[1]	670	[1]	1,884	[1]	1,967	[1]
Other Comprehensive Income	629		670		1,884		1,967
Comprehensive income	175,219		68,236		750,008		265,205
Comprehensive income attributable to noncontrolling interests	-450		-1,332		-7,872		-3,901
Comprehensive income attributable to Boston Properties Limited Partnership	$174,769		$66,904		$742,136		$261,304
[1]	Amounts reclassified from comprehensive income primarily to interest expense within the Company's Consolidated Statements of Operations.

Consolidated_Statements_Of_Par

Consolidated Statements Of Partners' Capital (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Increase (Decrease) in Partners' Capital [Roll Forward]	'	'
Beginning Balance	$3,330,605	$3,124,688
Contributions	196,968	249,100
Net income allocable to general and limited partner units	671,268	231,951
Distributions	-302,081	-248,014
Accumulated other comprehensive loss	1,695	1,759
Unearned compensation	3,811	3,340
Conversion of redeemable partnership units	10,406	11,236
Adjustment to reflect redeemable partnership units at redemption value	50,898	-186,130
Ending Balance	$3,963,570	$3,187,930

Consolidated_Statements_Of_Cas

Consolidated Statements Of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:	'	'
Net income	$748,124	$263,238
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation and amortization	403,957	327,355
Non-cash compensation expense	39,001	24,859
Impairment loss	4,401	0
Income from unconsolidated joint ventures	-72,240	-42,129
Gains on Consolidation of Joint Ventures	-385,991	0
Distributions of net cash flow from operations of unconsolidated joint ventures	29,607	32,359
Gains from investments in securities	-1,872	-1,202
Non-cash portion of interest expense	29,149	32,681
Settlement of accreted debt discount on repurchases of unsecured exchangeable senior notes	-56,532	-68,760
Gains from early extinguishments of debt	-264	-1,000
Gains on sale of real estate from discontinued operations	-88,565	-38,445
Gain on forgiveness of debt from discontinued operations	-20,736	0
Impairment loss from discontinued operations	2,852	0
Change in assets and liabilities:	'	'
Cash held in escrows	4,017	7,406
Tenant and other receivables, net	3,628	28,680
Accrued rental income, net	-44,636	-59,177
Prepaid expenses and other assets	-41,245	-29,925
Accounts payable and accrued expenses	9,179	3,713
Accrued interest payable	35,089	32,769
Other liabilities	-9,352	-6,939
Tenant leasing costs	-37,150	-41,797
Total adjustments	-197,703	200,448
Net cash provided by operating activities	550,421	463,686
Cash flows from investing activities:	'	'
Acquisitions of real estate	-522,900	-688,073
Construction in progress	-279,786	-238,627
Building and other capital improvements	-46,805	-32,159
Tenant improvements	-78,462	-108,100
Proceeds from sales of real estate	160,815	61,963
Cash recorded upon consolidation	79,468	0
Deposits on real estate	0	-15,000
Repayments of notes receivable, net	12,491	-1,764
Capital contributions to unconsolidated joint ventures	0	-367
Capital distributions from unconsolidated joint ventures	223,067	3,057
Investments in securities, net	-1,333	-1,042
Net cash used in investing activities	-453,445	-1,020,112
Cash flows from financing activities:	'	'
Repayments of mortgage notes payable	-96,750	-248,304
Proceeds from unsecured senior notes	1,194,753	997,790
Redemption of unsecured senior notes	0	-225,000
Redemption/Repurchase of unsecured exchangeable senior notes	-393,468	-507,434
Deferred financing costs	-15,180	-8,448
Net proceeds from preferred units issuance	193,623	0
Net proceeds from ATM stock issuances	0	247,186
Net proceeds from equity transactions	-348	216
Payments for redemption of preferred units	-43,070	-18,329
Distributions	-337,440	-278,994
Proceeds from noncontrolling interest in property partnership	6,386	0
Distributions to noncontrolling interest in property partnerships	-6,185	-2,250
Net cash provided by (used in) financing activities	502,321	-43,567
Net decrease)in cash and cash equivalents	599,297	-599,993
Cash and cash equivalents, beginning of period	1,041,978	1,823,208
Cash and cash equivalents, end of period	1,641,275	1,223,215
Supplemental disclosures:	'	'
Cash paid for interest	368,652	344,831
Interest capitalized	50,252	31,409
Non-cash investing and financing activities:	'	'
Additions to real estate included in accounts payable and accrued expenses	6,397	11,190
Real estate and related intangibles recorded upon consolidation	3,356,000	0
Debt recorded upon consolidation	2,056,000	0
Working capital recorded upon consolidation	97,847	0
Noncontrolling interest recorded upon consolidation	480,861	0
investment in unconsolidated joint venture elminated upon consolidation	361,808	0
Mortgage note payable extinguished through foreclosure	25,000	0
Real estate transferred upon foreclosure	7,508	0
Land improvements contributed by noncontrolling property partnership	4,546	0
Preferred Units Issued In Connection With Acquisition Of Real Estate	0	79,405
Distributions declared but not paid	112,470	93,461
Issuance of common stock in connection with the exchange of exchangeable senior notes	43,834	0
Conversions of redeemable partnership units to partners' capital	10,406	11,236
Conversion of redeemable preferred units to common units	0	5,852
Issuance of restricted securities to employees and directors	$30,077	$26,351

Organization

Organization	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Organization	'
	Organization
	Boston Properties Limited Partnership (the “Company”), a Delaware limited partnership, is the entity through which Boston Properties, Inc., a self-administered and self-managed real estate investment trust (“REIT”), conducts substantially all of its business and owns (either directly or through subsidiaries) substantially all of its assets. Boston Properties, Inc. is the sole general partner of the Company and at September 30, 2013 owned an approximate 89.2% (88.6% at September 30, 2012) general and limited partnership interest in the Company. Partnership interests in the Company are denominated as “common units of partnership interest” (also referred to as “OP Units”), “long term incentive units of partnership interest” (also referred to as “LTIP Units”) or “preferred units of partnership interest” (also referred to as “Preferred Units”). In addition, in February 2011 and February 2012, the Company issued LTIP Units in connection with the granting to employees of outperformance awards (also referred to as “2011 OPP Units” and “2012 OPP Units,” respectively, and collectively as “OPP Units”). In February 2013, the Company issued LTIP Units in connection with the granting to employees of 2013 MYLTIP Units (“2013 MYLTIP Units”). Because the rights, preferences and privileges of OPP Units and 2013 MYLTIP Units differ from other LTIP Units granted to employees as part of the annual compensation process, unless specifically noted otherwise, all references to LTIP Units exclude OPP Units and 2013 MYLTIP Units (See Notes 10 and 13).
	Unless specifically noted otherwise, all references to OP Units exclude units held by Boston Properties, Inc. A holder of an OP Unit may present such OP Unit to the Company for redemption at any time (subject to restrictions agreed upon at the time of issuance of OP Units to particular holders that may restrict such redemption right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, the Company is obligated to redeem such OP Unit for cash equal to the value of a share of common stock of Boston Properties, Inc. (“Common Stock”) at such time. In lieu of a cash redemption, Boston Properties, Inc. may elect to acquire such OP Unit for one share of Common Stock. Because the number of shares of Common Stock outstanding at all times equals the number of OP Units that Boston Properties, Inc. owns, one share of Common Stock is generally the economic equivalent of one OP Unit, and the quarterly distribution that may be paid to the holder of an OP Unit equals the quarterly dividend that may be paid to the holder of a share of Common Stock. An LTIP Unit is generally the economic equivalent of a share of restricted common stock of Boston Properties, Inc. LTIP Units, whether vested or not, will receive the same quarterly per unit distributions as OP Units, which equal per share dividends on Common Stock (See Note 11).
	At September 30, 2013, there were three series of Preferred Units outstanding (i.e., Series Two Preferred Units, Series Four Preferred Units and Series B Preferred Units). The Series Two Preferred Units bear a distribution that is set in accordance with an amendment to the partnership agreement of the Company. Each Series Two Preferred Unit may also be converted into approximately 1.312336 OP Units or redeemed for $50.00 of cash at the election of the holder thereof or the Company in accordance with the terms and conditions set forth in the applicable amendment to the partnership agreement. The Series Four Preferred Units are not convertible into or exchangeable for any common equity of the Company or Boston Properties, Inc., have a per unit liquidation preference of $50.00 and are entitled to receive quarterly distributions of $0.25 per unit (or an annual rate of 2.00%) (See Note 10). The Series B Preferred Units were issued to Boston Properties, Inc. on March 27, 2013 in connection with Boston Properties, Inc.'s issuance of 80,000 shares of 5.25% Series B Cumulative Redeemable Preferred Stock (the "Series B Preferred Stock"). Boston Properties, Inc. contributed the net proceeds from the offering to the Company in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock (See Note 11).
	All references herein to the Company refer to Boston Properties Limited Partnership and its consolidated subsidiaries, collectively, unless the context otherwise requires.
	Properties
	At September 30, 2013, the Company owned or had interests in a portfolio of 177 commercial real estate properties (the “Properties”) aggregating approximately 44.6 million net rentable square feet, including eight properties under construction totaling approximately 2.8 million net rentable square feet. In addition, the Company has structured parking for approximately 46,221 vehicles containing approximately 15.7 million square feet. At September 30, 2013, the Properties consist of:
	•	169 office properties, including 130 Class A office properties (including seven properties under construction) and 39 Office/Technical properties;
	•	one hotel;
	•	four retail properties; and
	•	three residential properties (including one property under construction).
	The Company owns or controls undeveloped land parcels totaling approximately 512.6 acres.
	The Company considers Class A office properties to be centrally located buildings that are professionally managed and maintained, attract high-quality tenants and command upper-tier rental rates, and that are modern structures or have been modernized to compete with newer buildings. The Company considers Office/Technical properties to be properties that support office, research and development, laboratory and other technical uses. The Company’s definitions of Class A Office and Office/Technical properties may be different than those used by other companies.

Basis_Of_Presentation_And_Summ

Basis Of Presentation And Summary Of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Basis Of Presentation And Summary Of Significant Accounting Policies	'
	Basis of Presentation and Summary of Significant Accounting Policies
	Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in the Company, nor does it have employees of its own. The Company, not Boston Properties, Inc., executes all significant business relationships. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities ("VIE"s) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.
	The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the disclosures required by accounting principles generally accepted in the United States of America for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by accounting principles generally accepted in the United States of America. These financial statements should be read in conjunction with the Company’s financial statements and notes thereto contained in the Company’s Annual Report in the Company’s Form 10-K for its fiscal year ended December 31, 2012. Certain prior year amounts have been reclassified to conform to the current year presentation. The Company has modified the presentation of expenses to operate its San Francisco and Princeton regional offices to reflect the growing activity in its San Francisco region and to have a consistent presentation across the Company. These expenses, which totaled approximately $2.0 million and $1.9 million for the three months ended September 30, 2013 and 2012, respectively, and approximately $6.1 million and $5.8 million for the nine months ended September 30, 2013 and 2012, respectively, were previously included in Rental Operating Expenses and are now included in General and Administrative Expenses for all periods presented.
	The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. The Company determines the fair value of its unsecured senior notes and unsecured exchangeable senior notes using market prices. The inputs used in determining the fair value of the Company’s unsecured senior notes and unsecured exchangeable senior notes is categorized at a level 1 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a level 2 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) if trading volumes are low. The Company determines the fair value of its mortgage notes payable using discounted cash flow analyses by discounting the spread between the future contractual interest payments and hypothetical future interest payments on mortgage debt based on current market rates for similar securities. In determining the current market rates, the Company adds its estimates of market spreads to the quoted yields on federal government treasury securities with similar maturity dates to its debt. The inputs used in determining the fair value of the Company’s mortgage notes payable are categorized at a level 3 basis (as defined in the accounting standards for Fair Value Measurements and Disclosures) due to the fact that the Company considers the rates used in the valuation techniques to be unobservable inputs.
	Because the Company’s valuations of its financial instruments are based on these types of estimates, the actual fair values of its financial instruments may differ materially if the Company’s estimates do not prove to be accurate. The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of September 30, 2013 and December 31, 2012 (in thousands):
		September 30, 2013							December 31, 2012
		Carrying				Estimated			Carrying				Estimated
		Amount				Fair Value			Amount				Fair Value
	Mortgage notes payable	$	4,468,069			$	4,592,273		$	3,102,485			$	3,256,940
	Mezzanine notes payable	311,340				311,366			—				—
	Unsecured senior notes	5,835,424				6,065,723			4,639,528				5,162,486
	Unsecured exchangeable senior notes	739,536			-1	768,019			1,170,356			-1	1,278,554
	Total	$	11,354,369			$	11,737,381		$	8,912,369			$	9,697,980
	_______________
	-1	Includes the net adjustment for the equity component allocation totaling approximately $7.4 million and $25.5 million at September 30, 2013 and December 31, 2012, respectively.
	Out-of-Period Adjustment
	During the nine months ended September 30, 2012, the Company recorded additional real estate operating expenses totaling approximately $3.2 million related to the cumulative non-cash straight-line adjustment to the ground rent expense of certain ground leases that were not previously recognized on a straight-line basis. This resulted in the overstatement of real estate operating expenses by approximately $3.2 million during the nine months ended September 30, 2012 and in the understatement of real estate operating expenses in the aggregate amount of approximately $3.2 million in previous periods. Because this adjustment was not material to the prior years’ consolidated financial statements and the impact of recording the adjustment in the then-current period was not material to the Company’s consolidated financial statements, the Company recorded the related adjustment during the nine months ended September 30, 2012.
	Revision of Prior Period Amounts
	The table below reflects selected information for the Company for the three and nine months ended September 30, 2012. The servicer of the non-recourse mortgage loan in the amount of $25.0 million collateralized by the Company's Montvale Center property located in Gaithersburg, Maryland foreclosed on the property on January 31, 2012. As a result of the foreclosure, the Company recognized a gain on forgiveness of debt during the nine months ended September 30, 2012 totaling approximately $18.4 million. Due to a procedural error of the trustee, the foreclosure sale was subsequently dismissed by the applicable court prior to ratification. As a result, the Company, as part of its Form 10-K for the fiscal year ended December 31, 2012, revised its financial statements to (1) properly reflect the property and related mortgage debt on its consolidated balance sheet at December 31, 2012, (2) reverse the gain on forgiveness of debt during the nine months ended September 30, 2012 and (3) recognize the operating activity from the property for the three and nine months ended September 30, 2012. On February 20, 2013, the subsequent foreclosure sale of Montvale Center was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.7 million during the nine months ended September 30, 2013 (See Note 3). As a result, for the three and nine months ended September 30, 2012, the activity for Montvale Center has been reclassified to discontinued operations in the consolidated statements of operations. In addition, operating results have been reclassified for the three and nine months ended September 30, 2012 as a result of the discontinued operations presentation of (1) the Company's Bedford Business Park properties which were sold on May 17, 2012, (2) the Company's 303 Almaden Boulevard property which was sold on June 28, 2013 (See Note 3) and (3) the Company's 1301 New York Avenue property which was sold on August 22, 2013 (See Note 3).
			For the three months ended September 30, 2012							For the nine months ended September 30, 2012
			As Reported				As Revised			As Reported				As Revised
			(in thousands, except for per unit amounts)
	Total revenue		$	470,904			$	466,680		$	1,389,028			$	1,376,448
	Income from continuing operations		$	68,147			$	66,016		$	225,430			$	219,197
	Discontinued operations		$	—			$	1,550		$	57,690			$	44,041
	Net income attributable to Boston Properties Limited Partnership		$	66,815			$	66,234		$	279,219			$	259,337
	Income attributable to Boston Properties Limited Partnership common unitholders per unit—basic		$	0.4			$	0.39		$	1.67			$	1.55
	Income attributable to Boston Properties Limited Partnership common unitholders per unit—diluted		$	0.39			$	0.39		$	1.66			$	1.54
	Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2013-02, "Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income" (“ASU No. 2013-02”). ASU No. 2013-02 requires an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income, but only if the amount reclassified is required to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional detail about those amounts. ASU No. 2013-02 is effective prospectively for reporting periods beginning after December 15, 2012. The Company’s adoption of ASU No. 2013-02 did not have a material impact on its consolidated financial statements.

Real_Estate_Activity_During_th

Real Estate Activity During the Nine Months Ended September 30, 2013	9 Months Ended
	Sep. 30, 2013
Real Estate [Abstract]	'
Real Estate Activity During The Nine Months Ended September 30, 2013	'
	Real Estate Activity During the Nine Months Ended September 30, 2013
	Acquisitions
	On February 6, 2013, the Company completed the acquisition of 535 Mission Street, a development site, in San Francisco, California for an aggregate purchase price of approximately $71.0 million in cash, including work completed and materials purchased to date. When completed, 535 Mission Street will consist of a 27-story, Class A office tower with approximately 307,000 net rentable square feet of office and retail space. The property is currently under development.
	On March 26, 2013, the consolidated joint venture in which the Company has a 95% interest completed the acquisition of a land parcel in San Francisco, California that will support a 60-story, 1.4 million square foot office tower known as Transbay Tower. The purchase price for the land was approximately $192.0 million. On February 7, 2013, the partner in the joint venture issued a notice that it was electing under the joint venture agreement to reduce its nominal ownership interest in the venture from 50% to 5%. On February 26, 2013, the Company issued a notice to the partner electing to proceed with the venture on that basis. As a result, the Company has a 95% nominal interest in and is consolidating the joint venture (See Note 10). The initial phase of the development consisting of building the project to grade is currently under development.
	On March 29, 2013, the Company completed the acquisition of a parcel of land located in Reston, Virginia for a purchase price of approximately $27.0 million. The land parcel is commercially zoned for 250,000 square feet of office space.
	On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from Boston Properties Office Value-Added Fund, L.P. (the "Value-Added Fund") for an aggregate net purchase price of approximately $233.1 million. Mountain View Research Park is a 16-building complex of Office/Technical properties aggregating approximately 604,000 net rentable square feet. Mountain View Technology Park is a seven-building complex of Office/Technical properties aggregating approximately 135,000 net rentable square feet. The following table summarizes the allocation of the aggregate purchase price of Mountain View Research Park and Mountain View Technology Park at the date of acquisition (in thousands).
	Land	$	126,521
	Building and improvements	82,451
	Tenant improvements	7,326
	In-place lease intangibles	23,279
	Above-market rents	843
	Below-market rents	(7,336		)
	Net assets acquired	$	233,084
	On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. 767 Fifth Avenue (the General Motors Building) is a Class A office property totaling approximately 1.8 million net rentable square feet. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that, effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Notes 5 and 10). The following table summarizes the allocation of the aggregate purchase price of 767 Fifth Avenue (the General Motors Building) at the date of consolidation on May 31, 2013 (in thousands).
	Real estate and related intangibles recorded upon consolidation
	Land	$	1,796,252
	Building and improvements	1,447,446
	Tenant improvements	85,208
	In-place lease intangibles	357,781
	Above market rents	101,897
	Below market rents	(239,641		)
	Above market assumed debt adjustments	(192,943		)
		$	3,356,000
	Debt recorded upon consolidation
	Mortgage notes payable	$	(1,300,000	)
	Mezzanine notes payable	(306,000		)
	Related party notes payable	(450,000		)	-1
		$	(2,056,000	)
	Working capital recorded upon consolidation
	Cash and cash equivalents	$	79,468
	Cash held in escrows	2,403
	Tenant and other receivables	7,104
	Prepaid expenses and other assets	4,269
	Accounts payable and accrued expenses	(2,418		)
	Accrued interest payable	(182,369		)	-2
	Other liabilities	(6,304		)
		$	(97,847	)
	Noncontrolling interest recorded upon consolidation
	Noncontrolling interests	$	(520,000	)
	Noncontrolling interests - working capital	39,139
		$	(480,861	)
	Net assets recorded upon consolidation	$	721,292
	_______________
	(1) The Company's partner loans totaling $270.0 million eliminates in consolidation.
	(2) The Company's share of the accrued interest payable on the partner loans totaling approximately $105.5 million eliminates in consolidation.
	Mountain View Research Park and Mountain View Technology Park contributed approximately $10.9 million of revenue and approximately $(0.1) million of earnings to the Company for the period from April 10, 2013 through September 30, 2013. 767 Fifth Avenue (the General Motors Building) contributed approximately $95.3 million of revenue and approximately $4.1 million of earnings to the Company for the period from May 31, 2013 through September 30, 2013.
	The accompanying unaudited pro forma information for the nine months ended September 30, 2013 and 2012 is presented as if the operating property acquisitions of (1) Mountain View Research Park and Mountain View Technology Park on April 10, 2013 and the approximately $26.5 million gain on consolidation and (2) 767 Fifth Avenue (the General Motors Building) on May 31, 2013 and the approximately $359.5 million gain on consolidation, had occurred on January 1, 2012. This unaudited pro forma information is based upon the historical consolidated financial statements of the Company and should be read in conjunction with the consolidated financial statements and notes thereto. This pro forma information does not purport to represent what the actual results of operations of the Company would have been had the above occurred, nor do they purport to predict the results of operations of future periods.
	Pro Forma (Unaudited)	Nine Months Ended September 30,
	(in thousands, except per unit data)	2013				2012
	Total revenue	$	1,688,393			$	1,602,949
	Income from continuing operations	$	234,784			$	573,170
	Net income attributable to Boston Properties Limited Partnership	$	351,549			$	633,626
	Basic earnings per unit:
	Net income per unit attributable to Boston Properties Limited Partnership	$	2.08			$	3.76
	Diluted earnings per unit:
	Net income per unit attributable to Boston Properties Limited Partnership	$	2.07			$	3.75
	Developments
	On March 22, 2013, the Company completed and fully placed in-service Two Patriots Park, a Class A office redevelopment project with approximately 256,000 net rentable square feet located in Reston, Virginia.
	On April 25, 2013, the Company commenced construction of its 601 Massachusetts Avenue development project totaling approximately 478,000 net rentable square feet located in Washington, DC.
	On June 14, 2013, the Company completed and fully placed in-service 17 Cambridge Center, a Class A office project with approximately 195,000 net rentable square feet located in Cambridge, Massachusetts.
	On July 1, 2013, the Company completed and fully placed in-service its Cambridge Center Connector project with approximately 43,000 net rentable square feet located in Cambridge, Massachusetts.
	Dispositions
	On February 20, 2013, the foreclosure sale of the Company's Montvale Center property was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.7 million. The operating results of the property through the date of ratification have been classified as discontinued operations on a historical basis for all periods presented.
On June 28, 2013, the Company completed the sale of its 303 Almaden Boulevard property located in San Jose, California for a sale price of $40.0 million. Net cash proceeds totaled approximately $39.3 million. 303 Almaden Boulevard is a Class A office property totaling approximately 158,000 net rentable square feet. Because the Company entered into the related purchase and sale agreement on March 28, 2013 and the carrying value of the property exceeded its net sale price, the Company recognized an impairment loss totaling approximately $2.9 million during the three months ended March 31, 2013. As a result, there was no loss on sale of real estate recognized during the nine months ended September 30, 2013. The impairment loss and operating results of this property have been classified as discontinued operations on a historical basis for all periods presented. The sale of this asset caused the Company to reevaluate its strategy for development of its adjacent Almaden land parcel, which can accommodate an approximately 840,000 square feet office complex.  Based on a shorter than expected hold period, the Company reduced the carrying value of the land parcel to its estimated fair market value and recognized an impairment loss of approximately $4.4 million during the three months ended March 31, 2013. The Company's estimated fair value, as measured on a non-recurring basis, was based on comparable land sales. The Company has determined that its valuation of the land falls within Level 3 of the fair value hierarchy, as it has utilized significant unobservable inputs in its assessment.
On August 22, 2013, the Company completed the sale of its 1301 New York Avenue property located in Washington, DC for a net contract sale price of approximately $121.7 million. After adjusting for outstanding lease and other transaction costs assumed by the buyer, the gross sale price was approximately $135.0 million. Net cash proceeds totaled approximately$121.5 million resulting in a gain on sale of approximately $88.6 million. 1301 New York Avenue is a Class A office property totaling approximately 201,000 net rentable square feet. The operating results of the property through the date of sale have been classified as discontinued operations on a historical basis for all periods presented.
The following table summarizes the income from discontinued operations related to 1301 New York Avenue, Montvale Center and 303 Almaden Boulevard and the related gain on sale of real estate, gain on forgiveness of debt and impairment loss for the three and nine months ended September 30, 2013 and 2012 and the gain on sale of real estate and income from discontinued operations for the nine months ended September 30, 2012 related to the Company's Bedford Business Park properties which were sold on May 17, 2012:
	For the three months ended September 30,							For the nine months ended September 30,
	2013				2012			2013			2012
	(in thousands)
Total revenue	$	1,511			$	4,882		$	10,469		$	17,940
Expenses
Operating	433				1,781			3,447			6,725
Depreciation and amortization	—				901			1,065			3,675
Total expenses	433				2,682			4,512			10,400
Operating income	1,078				2,200			5,957			7,540
Other expense
Interest expense	—				(650		)	(360		)	(1,944		)
Income from discontinued operations	$	1,078			$	1,550		$	5,597		$	5,596
Gains on sales of real estate from discontinued operations	$	88,565			$	—		$	88,565		$	38,445
Gain on forgiveness of debt from discontinued operations	$	—			$	—		$	20,736		$	—
Impairment loss from discontinued operations	$	—			$	—		$	(2,852	)	$	—

Investments_in_Unconsolidated_

Investments in Unconsolidated Joint Ventures	9 Months Ended
	Sep. 30, 2013
Investments In Unconsolidated Joint Ventures [Abstract]	'
Investments In Unconsolidated Joint Ventures	'
	Investments in Unconsolidated Joint Ventures
	The investments in unconsolidated joint ventures consist of the following at September 30, 2013:
	Entity		Properties		Nominal %
					Ownership
	Square 407 Limited Partnership		Market Square North		50	%
	The Metropolitan Square Associates LLC		Metropolitan Square		51	%
	BP/CRF 901 New York Avenue LLC		901 New York Avenue		25	%	(1)
	WP Project Developer LLC		Wisconsin Place Land and Infrastructure		33.3	%	(2)
	RBP Joint Venture LLC		N/A		50	%	(3)
	Boston Properties Office Value-Added Fund, L.P.		N/A		39.5	%	-4
	Annapolis Junction NFM, LLC		Annapolis Junction		50	%	(5)
	2 GCT Venture LLC		N/A		60	%	(6)
	540 Madison Venture LLC		540 Madison Avenue		60	%
	125 West 55th Street Venture LLC		N/A		60	%	-7
	500 North Capitol LLC		500 North Capitol Street, NW		30	%
	_______________
	-1	The Company’s economic ownership can increase based on the achievement of certain return thresholds.
	-2	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land and infrastructure of the project.
	-3	Eighth Avenue and 46th Street was sold on July 19, 2013.
	-4	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of September 30, 2013, the investment is comprised of undistributed cash.
	-5	Comprised of two buildings, one building under construction and two undeveloped land parcels.
	-6	Two Grand Central Tower was sold on October 25, 2011. As of September 30, 2013, the investment is comprised of undistributed cash.
	-7	125 West 55th Street was sold on May 30, 2013. As of September 30, 2013, the investment is comprised of undistributed cash.
	Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures at an agreed upon fair value. Under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners.
	The combined summarized balance sheets of the Company's unconsolidated joint ventures are as follows:
		September 30, 2013				December 31,
						2012
		(in thousands)
	ASSETS
	Real estate and development in process, net	$	927,890			$	4,494,971
	Other assets	158,105				673,716
	Total assets	$	1,085,995			$	5,168,687
	LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
	Mortgage and notes payable	$	748,489			$	3,039,922
	Other liabilities	21,183				792,888
	Members’/Partners’ equity	316,323				1,335,877
	Total liabilities and members’/partners’ equity	$	1,085,995			$	5,168,687
	Company’s share of equity	$	157,875			$	787,941
	Basis differentials (1)	(28,837		)		(128,025		)
	Carrying value of the Company’s investments in unconsolidated joint ventures	$	129,038			$	659,916
	_______________
	-1	This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from impairment of investments and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level.
	The combined summarized statements of operations of the Company's unconsolidated joint ventures are as follows:
		For the three months ended September 30,							For the nine months ended September 30,
		2013				2012			2013			2012
		(in thousands)
	Total revenue (1)	$	37,983			$	135,998		$	273,464		$	431,133
	Expenses
	Operating	14,963				42,298			89,826			120,451
	Depreciation and amortization	9,784				39,291			76,202			123,869
	Total expenses	24,747				81,589			166,028			244,320
	Operating income	13,236				54,409			107,436			186,813
	Other income (expense)
	Interest expense	(8,148		)		(56,521		)	(104,436		)	(167,792		)
	Losses from early extinguishments of debt	—				—			(1,677		)	—
	Income (loss) from continuing operations	5,088				(2,112		)	1,323			19,021
	Gains on sales of real estate	12,441				990			14,207			990
	Net income (loss)	$	17,529			$	(1,122	)	$	15,530		$	20,011
	Company’s share of net income (loss)	$	3,149			$	(1,420	)	$	1,974		$	10,591
	Gains on sales of real estate	11,174				—			54,501			—
	Basis differential	413				384			(1,213		)	1,282
	Elimination of inter-entity interest on partner loan	—				10,253			16,978			30,256
	Income from unconsolidated joint ventures	$	14,736			$	9,217		$	72,240		$	42,129
Gains on consolidation of joint ventures	$	(1,810	)		$	—		$	385,991		$	—
_______________
-1	Includes straight-line rent adjustments of $0.6 million and $2.2 million for the three months ended September 30, 2013 and 2012, respectively, and $7.6 million and $9.3 million for the nine months ended September 30, 2013 and 2012, respectively. Includes net below-market rent adjustments of $(0.1) million and $22.1 million for the three months ended September 30, 2013 and 2012, respectively, and $33.9 million and $70.6 million for the nine months ended September 30, 2013 and 2012, respectively. Total revenue for the nine months ended September 30, 2012 includes termination income totaling approximately $19.6 million (of which the Company's share is approximately $11.8 million) related to a lease termination with a tenant at 767 Fifth Avenue (the General Motors Building).
On February 28, 2013, a joint venture in which the Company has a 50% interest completed and fully placed in-service Annapolis Junction Building Six, a Class A office property with approximately 119,000 net rentable square feet located in Annapolis, Maryland.
On March 31, 2013, a joint venture in which the Company has a 30% interest completed and fully placed in-service 500 North Capitol Street, NW, a Class A office redevelopment project with approximately 231,000 net rentable square feet located in Washington, DC.
On April 4, 2013, a joint venture in which the Company has a 50% interest obtained construction financing collateralized by its Annapolis Junction Building Seven development project located in Annapolis, Maryland totaling $22.0 million. The construction financing bears interest at a variable rate equal to LIBOR plus 1.65% per annum and matures on April 4, 2016, with two, one-year extension options, subject to certain conditions.
On April 10, 2013, the Company acquired the Mountain View Research Park and Mountain View Technology Park properties from its Value-Added Fund for an aggregate net purchase price of approximately $233.1 million. In conjunction with the acquisition, the Value-Added Fund repaid the mortgage loans collateralized by the Mountain View Research Park and Mountain View Technology Park properties totaling approximately $90.0 million and $20.0 million, respectively, as well as the outstanding loans payable to the Company totaling approximately $8.6 million and $3.7 million, respectively. The Mountain View Research Park and Mountain View Technology Park mortgage loans bore interest at variable rates equal to LIBOR plus 2.00% per annum and LIBOR plus 2.50% per annum, respectively and were scheduled to mature on May 31, 2014 and November 22, 2014, respectively. The joint venture recognized a loss on early extinguishment of debt totaling approximately $0.4 million, of which the Company's share was approximately $0.2 million, consisting of the write-off of unamortized deferred financing costs. Prior to the acquisition, the Company's ownership interest in the properties was approximately 39.5%. As a result of the acquisition, the Company owns 100% of the properties and is accounting for them on a consolidated basis (See Note 3). The Company had previously recognized an impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on its investment of approximately $26.5 million, which includes an adjustment recognized during the three months ended September 30, 2013 totaling approximately $2.1 million and which is included within gains on consolidation of joint ventures in the Company's consolidated statements of operations.
On May 30, 2013, a joint venture in which the Company has a 60% interest completed the sale of its 125 West 55th Street property located in New York City for a sale price of $470.0 million, including the assumption by the buyer of the mortgage loan collateralized by the property totaling approximately $198.6 million. The mortgage loan bore interest at a fixed rate of 6.09% per annum and was scheduled to mature on March 10, 2020. Net cash proceeds totaled approximately $253.7 million, of which the Company's share was approximately $152.2 million, after the payment of transaction costs. 125 West 55th Street is a Class A office property totaling approximately 588,000 net rentable square feet. The Company had previously recognized an impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on sale of real estate totaling approximately $43.2 million, which is included within income from unconsolidated joint ventures in the Company's consolidated statements of operations.
On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting (See Note 3). Upon consolidation, the Company recognized a non-cash gain on its investment of approximately $359.5 million, which includes an adjustment recognized during the three months ended September 30, 2013 totaling approximately $(3.9) million and which is included within gains on consolidation of joint ventures in the Company's consolidated statements of operations.
On May 31, 2013, a joint venture in which the Company has a 30% interest refinanced its construction loan collateralized by 500 North Capitol Street, NW located in Washington, DC. The construction loan totaling approximately $90.6 million bore interest at a variable rate equal to LIBOR plus 1.65% per annum and was scheduled to mature on October 14, 2014. The joint venture recognized a loss on early extinguishment of debt totaling approximately $1.0 million, of which the Company's share was approximately $0.3 million, consisting of the write-off of unamortized deferred financing costs. The new mortgage loan totaling $105.0 million requires interest only payments at a fixed interest rate of 4.15% per annum and matures on June 6, 2023.
On June 5, 2013, a joint venture in which the Company has a 60% interest refinanced its mortgage loans collateralized by 540 Madison Avenue located in New York City. The mortgage loans aggregating approximately $118.0 million bore interest at a weighted-average fixed rate of 5.20% per annum and were scheduled to mature on July 11, 2013. The joint venture recognized a loss on early extinguishment of debt totaling approximately $0.3 million, of which the Company's share was approximately $0.2 million, related to the acceleration of the remaining balance of the historical fair value debt adjustment, which was the result of purchase accounting. The new mortgage loan totaling $120.0 million requires interest only payments at a variable rate equal to LIBOR plus 1.50% per annum and matures on June 5, 2018.
On July 19, 2013, a joint venture in which the Company has a 50% interest completed the sale of its Eighth Avenue and 46th Street project located in New York City for an imputed sale price of $45.0 million. The Eighth Avenue and 46th Street project is comprised of an assemblage of land parcels and air-rights. Net cash proceeds to the Company totaled approximately $21.8 million, after the payment of transaction costs. The joint venture had previously recognized an impairment loss on the property. As a result, the joint venture recognized a gain on sale of real estate totaling approximately $12.6 million, of which the Company's share was approximately $11.3 million. The Company's share of the gain on sale of real estate is reflective of the Company's share of the net proceeds from the imputed sale price and is included within income from unconsolidated joint ventures in the Company's consolidated statements of operations.
On September 26, 2013, a joint venture in which the Company has a 50% interest entered into a lease agreement for its Annapolis Junction Building Seven development project. Annapolis Junction Building Seven when completed will consist of a Class A office property with approximately 125,000 net rentable square feet located in Annapolis, Maryland.

Mortgage_Notes_Payable

Mortgage Notes Payable	9 Months Ended
	Sep. 30, 2013
Loans Payable [Abstract]	'
Mortgage Notes Payable	'
	Mortgage Notes Payable
	On February 5, 2013, the Company used available cash to repay the mortgage loan collateralized by its Kingstowne One property located in Alexandria, Virginia totaling approximately $17.0 million. The mortgage loan bore interest at a fixed rate of 5.96% per annum and was scheduled to mature on May 5, 2013. There was no prepayment penalty.
	On February 20, 2013, the foreclosure sale of the Company's Montvale Center property was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.7 million. The operating results of the property through the date of ratification have been classified as discontinued operations on a historical basis for all periods (See Notes 2 and 3).
	On April 1, 2013, the Company used available cash to repay the mortgage loan collateralized by its 140 Kendrick Street property located in Needham, Massachusetts totaling approximately $47.6 million. The mortgage loan bore interest at a fixed rate of 7.51% per annum and was scheduled to mature on July 1, 2013. There was no prepayment penalty. The Company recognized a gain on early extinguishment of debt totaling approximately $0.3 million related to the acceleration of the remaining balance of the historical fair value debt adjustment, which was the result of purchase accounting.
	On May 31, 2013, in conjunction with the consolidation of the Company's 767 Venture, LLC joint venture (the entity that owns 767 Fifth Avenue (the General Motors Building), the Company recorded mortgage loans collateralized by the property aggregating $1.3 billion and mezzanine loans aggregating $306.0 million. The mortgage loans require interest-only payments at a weighted-average fixed interest rate of 5.95% per annum and mature on October 7, 2017. The mezzanine loans require interest-only payments at a weighted-average fixed interest rate of 6.02% per annum and mature on October 7, 2017. The mortgage loans and mezzanine loans were recorded at their fair values aggregating approximately $1.5 billion and $311.7 million, respectively, using weighted-average effective interest rates of approximately 2.44% and 5.53% per annum, respectively. In addition, in conjunction with the consolidation, the Company recorded loans payable to the joint venture's partners totaling $450.0 million and related accrued interest payable totaling approximately $175.8 million. The partner loans bear interest at a fixed rate of 11.0% per annum and mature on June 9, 2017. The Company has eliminated in consolidation its partner loan totaling $270.0 million and its share of the related accrued interest payable. The remaining notes payable to the outside joint venture partners totaling $180.0 million have been reflected as Related Party Notes Payable on the Consolidated Balance Sheets (See Note 3).

Unsecured_Senior_Notes_Unsecur

Unsecured Senior Notes Unsecured Senior Notes	9 Months Ended
	Sep. 30, 2013
Unsecured Senior Notes [Abstract]	'
Unsecured Senior Notes	'
	6. Unsecured Senior Notes
	The following summarizes the unsecured senior notes outstanding as of September 30, 2013 (dollars in thousands):
		Coupon/		Effective		Principal			Maturity Date(2)
		Stated Rate		Rate(1)		Amount
	12 Year Unsecured Senior Notes	5.625	%	5.693	%	$	300,000		April 15, 2015
	12 Year Unsecured Senior Notes	5	%	5.194	%	250,000			June 1, 2015
	10 Year Unsecured Senior Notes	5.875	%	5.967	%	700,000			15-Oct-19
	10 Year Unsecured Senior Notes	5.625	%	5.708	%	700,000			15-Nov-20
	10 Year Unsecured Senior Notes	4.125	%	4.289	%	850,000			15-May-21
	7 Year Unsecured Senior Notes	3.7	%	3.853	%	850,000			November 15, 2018
	11 Year Unsecured Senior Notes	3.85	%	3.954	%	1,000,000			February 1, 2023
	10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
	10.5 Year Unsecured Senior Notes	3.8	%	3.916	%	700,000			February 1, 2024
	Total principal					5,850,000
	Net unamortized discount					(14,576		)
	Total					$	5,835,424
	_______________
	-1	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.
	-2	No principal amounts are due prior to maturity.
	The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At September 30, 2013, the Company was in compliance with each of these financial restrictions and requirements.
	On April 11, 2013, the Company completed a public offering of $500.0 million in aggregate principal amount of its 3.125% senior unsecured notes due 2023. The notes were priced at 99.379% of the principal amount to yield an effective rate (including financing fees) of 3.279% to maturity. The notes will mature on September 1, 2023, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $492.5 million after deducting underwriting discounts and transaction expenses.
	On June 27, 2013, the Company completed a public offering of $700.0 million in aggregate principal amount of its 3.800% senior unsecured notes due 2024. The notes were priced at 99.694% of the principal amount to yield an effective rate (including financing fees) of 3.916% to maturity. The notes will mature on February 1, 2024, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $691.9 million after deducting the underwriting discount and transaction expenses.

Unsecured_Exchangeable_Senior_

Unsecured Exchangeable Senior Notes Unsecured Exchangeable Senior Notes

9 Months Ended

Sep. 30, 2013

Unsecured Exchangeable Senior Notes [Abstract]

'

Unsecured Exchangeable Senior Notes

'

7. Unsecured Exchangeable Senior Notes

The following summarizes the unsecured exchangeable senior notes outstanding as of September 30, 2013 (dollars in thousands):

Coupon/

Effective

Exchange

Principal

First Optional

Maturity Date

Stated Rate

Rate(1)

Rate

Amount

Redemption Date by the

Company

3.625% Exchangeable Senior Notes

3.625

%

4.037

%

8.5051

-2

$

747,500

N/A

February 15, 2014

Net unamortized discount

(555

)

Adjustment for the equity component allocation, net of accumulated amortization

(7,409

)

Total

$

739,536

_______________

-1

Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs but excluding the effects of the adjustment for the equity component allocation.

-2

The initial exchange rate is 8.5051 shares per $1,000 principal amount of the notes (or an initial exchange price of approximately $117.58 per share of Boston Properties, Inc.’s common stock). In addition, the Company entered into capped call transactions with affiliates of certain of the initial purchasers, which are intended to reduce the potential dilution upon future exchange of the notes. The capped call transactions were intended to increase the effective exchange price to the Company of the notes from $117.58 to approximately $137.17 per share (subject to adjustment), representing an overall effective premium of approximately 40% over the closing price on August 13, 2008 of $97.98 per share of Boston Properties, Inc.’s common stock. The net cost of the capped call transactions was approximately $44.4 million. As of September 30, 2013, the effective exchange price was $134.14 per share.

On April 15, 2013, the Company announced that holders of its 3.75% Exchangeable Senior Notes due 2036 (the “Notes”) had the right to surrender their Notes for purchase by the Company (the “Put Right”) on May 18, 2013. On April 15, 2013, the Company also announced that it had issued a notice of redemption to the holders of the Notes to redeem, on May 18, 2013 (the “Redemption Date”), all of the Notes outstanding on the Redemption Date. In connection with the notice of redemption, holders of the Notes had the right to exchange their Notes on or prior to May 16, 2013. Notes with respect to which the Put Right was not exercised and that were not surrendered for exchange on or prior to May 16, 2013, were redeemed by the Company at a redemption price equal to 100% of the principal amount of the Notes plus accrued and unpaid interest thereon to, but excluding, the Redemption Date. Based on final information provided to the Company by the trustee for the Notes, no Notes were validly tendered and accepted for purchase in the Put Right. Pursuant to the notice of redemption, an aggregate principal amount of $990,000 of the Notes was redeemed on May 18, 2013. The remaining aggregate principal amount of $449,010,000 of the Notes was surrendered for exchange and, in addition to the repayment of the principal in cash, Boston Properties, Inc. issued an aggregate of 419,116 shares of its common stock in exchange for the Notes (See Note 11). The Company recognized a loss on early extinguishment of debt totaling approximately $0.1 million consisting of transaction costs.

Unsecured_Line_of_Credit_Notes

Unsecured Line of Credit (Notes)	9 Months Ended
	Sep. 30, 2013
Unsecured Line of Credit [Abstract]	'
Unsecured Line of Credit [Text Block]	'
	8. Unsecured Line of Credit
	On July 26, 2013, the Company amended and restated the revolving credit agreement governing the Company's Unsecured Line of Credit, which, among other things, (1) increased the total commitment from $750.0 million to $1.0 billion, (2) extended the maturity date from June 24, 2014 to July 26, 2018 and (3) reduced the per annum variable interest rates and other fees. The Company may increase the total commitment to $1.5 billion, subject to syndication of the increase and other conditions. At the Company's option, loans outstanding under the Unsecured Line of Credit will bear interest at a rate per annum equal to (1), in the case of loans denominated in Dollars, Euro or Sterling, LIBOR or, in the case of loans denominated in Canadian Dollars, CDOR, in each case, plus a margin ranging from0.925% to 1.70% based on the Company’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Administrative Agent’s prime rate, (b) the Federal Funds rate plus 0.5% or (c) LIBOR for a one month period plus 1.00%, in each case, plus a margin ranging from 0.0% to 0.70% based on the Company’s credit rating. The Unsecured Line of Credit also contains a competitive bid option that allows banks that are part of the lender consortium to bid to make loan advances to the Company at a reduced interest rate. In addition, the Company is also obligated to pay (1) in quarterly installments a facility fee on the total commitment at a rate per annum ranging from 0.125% to 0.35% based on the Company’s credit rating and (2) an annual fee on the undrawn amount of each letter of credit equal to the LIBOR margin. Based on the Company’s current credit rating, the LIBOR and CDOR margin is 1.00%, the alternate base rate margin is 0.0% and the facility fee is 0.15%. At September 30, 2013, there were no amounts outstanding on the Unsecured Line of Credit.
	The terms of the Unsecured Line of Credit require that the Company maintain a number of customary financial and other covenants on an ongoing basis, including: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments. At September 30, 2013, the Company was in compliance with each of these financial and other covenant requirements.

Commitments_And_Contingencies

Commitments And Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments And Contingencies	'
	Commitments and Contingencies
	General
	In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence. In addition, in the normal course of business, the Company guarantees to certain tenants the obligations of its subsidiaries for the payment of tenant improvement allowances and brokerage commissions in connection with their leases and limited costs arising from delays in delivery of their premises.
	The Company has letter of credit and performance obligations of approximately $13.9 million related to lender and development requirements.
	Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures. Under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners.
	In connection with the assumption of 767 Fifth Avenue's (the General Motors Building) secured loan by the Company’s consolidated joint venture, 767 Venture, LLC, the Company guaranteed the consolidated joint venture’s obligation to fund various escrows, including tenant improvements, taxes and insurance in lieu of cash deposits. As of September 30, 2013, the maximum funding obligation under the guarantee was approximately $11.4 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee.
	In connection with the mortgage financing collateralized by the Company's John Hancock Tower property located in Boston, Massachusetts, the Company has agreed to guarantee approximately $15.9 million related to its obligations to provide funds for certain tenant re-leasing costs. The mortgage financing matures on January 6, 2017.
	From time to time, the Company (or the applicable joint venture) has also agreed to guarantee portions of the principal, interest or other amounts in connection with other unconsolidated joint venture borrowings. In addition to the financial guarantees referenced above, the Company has agreed to customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) on certain of its unconsolidated joint venture loans.
	Insurance
	The Company carries insurance coverage on its properties of types and in amounts and with deductibles that it believes are in line with coverage customarily obtained by owners of similar properties. In response to the uncertainty in the insurance market following the terrorist attacks of September 11, 2001, the Federal Terrorism Risk Insurance Act (as amended, “TRIA”) was enacted in November 2002 to require regulated insurers to make available coverage for “certified” acts of terrorism (as defined by the statute). The expiration date of TRIA was extended to December 31, 2014 by the Terrorism Risk Insurance Program Reauthorization Act of 2007 (“TRIPRA”) and the Company can provide no assurance that it will be extended further. Currently, the Company’s property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism certified under TRIA other than nuclear, biological, chemical or radiological terrorism (“Terrorism Coverage”). The Company also carries $250 million of Terrorism Coverage for 601 Lexington Avenue, New York, New York (“601 Lexington Avenue”) in excess of the $1.0 billion of coverage in the Company’s property insurance program which is provided by IXP, LLC (“IXP”) as a direct insurer. Certain properties, including the General Motors Building located at 767 Fifth Avenue in New York, New York (“767 Fifth Avenue”), are currently insured in separate insurance programs. The property insurance program per occurrence limits for 767 Fifth Avenue are $1.625 billion, including Terrorism Coverage, with $1.375 billion of Terrorism Coverage in excess of $250 million being provided by NYXP, LLC (“NYXP”), as a direct insurer. The Company also currently carries nuclear, biological, chemical and radiological terrorism insurance coverage for acts of terrorism certified under TRIA (“NBCR Coverage”), which is provided by IXP as a direct insurer, for the properties in our portfolio, including 767 Fifth Avenue, but excluding certain other properties owned in joint ventures with third parties or which the Company manages. The per occurrence limit for NBCR Coverage is $1.0 billion. Under TRIA, after the payment of the required deductible and coinsurance, the additional Terrorism Coverage provided by IXP for 601 Lexington Avenue, the NBCR Coverage provided by IXP and the Terrorism Coverage provided by NYXP are backstopped by the Federal Government if the aggregate industry insured losses resulting from a certified act of terrorism exceed a “program trigger.” The program trigger is $100.0 million and the coinsurance is 15%. Under TRIPRA, if the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIPRA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if there is a change in its portfolio or for any other reason. In the event TRIPRA is not extended beyond December 31, 2014, (i) the Company will evaluate alternative approaches to secure coverage for acts of terrorism thereby potentially increasing its overall cost of insurance, (ii) if such insurance is not available at commercially reasonable rates with limits equal to its current coverage or at all, the Company may not continue to have full occurrence limit coverage for acts of terrorism, (iii) the Company may not satisfy the insurance requirements under existing or future debt financings secured by individual properties, (iv) the Company may not be able to obtain future debt financings secured by individual properties and (v) the Company may cancel the insurance policies issued by IXP for the NBCR Coverage and the additional Terrorism Coverage for 601 Lexington Avenue and by NYXP for the Terrorism Coverage for 767 Fifth Avenue. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance and maintain terrorism insurance in amounts and on terms that are commercially reasonable.
	The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes in an amount and subject to self-insurance that the Company believes are commercially reasonable. In addition, this insurance is subject to a deductible in the amount of 5% of the value of the affected property. Specifically, the Company currently carries earthquake insurance which covers its San Francisco region (excluding 680 Folsom Street and 535 Mission Street) with a $120 million per occurrence limit and a $120 million annual aggregate limit, $20 million of which is provided by IXP, as a direct insurer. The builders risk policy maintained for the development of 680 Folsom Street in San Francisco includes a $20 million per occurrence and annual aggregate limit of earthquake coverage. In addition, the builders risk policy maintained for the development of 535 Mission Street in San Francisco includes a $15 million per occurrence and annual aggregate limit of earthquake coverage. The amount of the Company’s earthquake insurance coverage may not be sufficient to cover losses from earthquakes. In addition, the amount of earthquake coverage could impact the Company’s ability to finance properties subject to earthquake risk. The Company may discontinue earthquake insurance or change the structure of its earthquake insurance program on some or all of its properties in the future if the premiums exceed the Company’s estimation of the value of the coverage.
	IXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s earthquake insurance coverage for its Greater San Francisco properties, the additional Terrorism Coverage for 601 Lexington Avenue and the Company’s NBCR Coverage. The additional Terrorism Coverage provided by IXP for 601 Lexington Avenue only applies to losses which exceed the program trigger under TRIA. NYXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s Terrorism Coverage for 767 Fifth Avenue. Currently, NYXP only insures losses which exceed the program trigger under TRIA and NYXP reinsures with a third-party insurance company any coinsurance payable under TRIA. Insofar as the Company owns IXP and NYXP, it is responsible for their liquidity and capital resources, and the accounts of IXP and NYXP are part of the Company’s consolidated financial statements. In particular, if a loss occurs which is covered by the Company’s NBCR Coverage but is less than the applicable program trigger under TRIA, IXP would be responsible for the full amount of the loss without any backstop by the Federal Government. IXP and NYXP would also be responsible for any recoupment charges by the Federal Government in the event losses are paid out and their insurance policies are maintained after the payout by the Federal Government. If the Company experiences a loss and IXP or NYXP are required to pay under their insurance policies, the Company would ultimately record the loss to the extent of the required payment. Therefore, insurance coverage provided by IXP and NYXP should not be considered as the equivalent of third-party insurance, but rather as a modified form of self-insurance. In addition, the Company has issued a guarantee to cover liabilities of IXP in the amount of $20.0 million.
	The mortgages on the Company's properties typically contain requirements concerning the financial ratings of the insurers who provide policies covering the property. The Company provides the lenders on a regular basis with the identity of the insurance companies in the Company's insurance programs. The ratings of some of the Company's insurers are below the rating requirements in some of the Company's loan agreements and the lenders for these loans could attempt to claim that an event of default has occurred under the loan. The Company believes it could obtain insurance with insurers which satisfy the rating requirements. Additionally, in the future, the Company's ability to obtain debt financing secured by individual properties, or the terms of such financing, may be adversely affected if lenders generally insist on ratings for insurers or amounts of insurance which are difficult to obtain or which result in a commercially unreasonable premium. There can be no assurance that a deficiency in the financial ratings of one or more of the Company's insurers will not have a material adverse effect on the Company.
	The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism and California earthquake risk in particular, but the Company cannot anticipate what coverage will be available on commercially reasonable terms in future policy years. There are other types of losses, such as from wars, for which the Company cannot obtain insurance at all or at a reasonable cost. With respect to such losses and losses from acts of terrorism, earthquakes or other catastrophic events, if the Company experiences a loss that is uninsured or that exceeds policy limits, the Company could lose the capital invested in the damaged properties, as well as the anticipated future revenues from those properties. Depending on the specific circumstances of each affected property, it is possible that the Company could be liable for mortgage indebtedness or other obligations related to the property. Any such loss could materially and adversely affect the Company's business and financial condition and results of operations.

Noncontrolling_Interests

Noncontrolling Interests	9 Months Ended
	Sep. 30, 2013
Noncontrolling Interest [Abstract]	'
Noncontrolling Interests	'
	Noncontrolling Interests
	Noncontrolling interests relate to the interests in the Company not owned by Boston Properties, Inc. and interests in consolidated property partnerships not wholly-owned by the Company. As of September 30, 2013, the noncontrolling interests in the Company consisted of 15,738,523 OP Units, 1,460,200 LTIP Units, 396,500 2011 OPP Units, 396,150 2012 OPP Units, 316,325 2013 MYLTIP Units, 995,997 Series Two Preferred Units (or 1,307,083 OP Units on an as converted basis) and 360,126 Series Four Preferred Units (not convertible into OP Units) held by parties other than Boston Properties, Inc.
	Noncontrolling Interest—Redeemable Interest in Property Partnership
	On October 4, 2012, the Company completed the formation of a joint venture, which owns and operates Fountain Square located in Reston, Virginia. The joint venture partner contributed the property valued at approximately $385.0 million and related mortgage indebtedness totaling approximately $211.3 million for a nominal 50% interest in the joint venture. The Company contributed cash totaling approximately $87.0 million for its nominal 50% interest, which cash was distributed to the joint venture partner. Pursuant to the joint venture agreement (i) the Company has rights to acquire the partner's nominal 50% interest and (ii) the partner has the right to cause the Company to acquire the partner's interest on January 4, 2016, in each case at a fixed price totaling approximately $102.0 million in cash. The fixed price option rights expire on January 31, 2016. The Company is consolidating this joint venture due to the Company's right to acquire the partner's nominal 50% interest. The Company initially recorded the noncontrolling interest at its acquisition-date fair value as temporary equity, due to the redemption option existing outside the control of the Company. The Company will accrete the changes in the redemption value quarterly over the period from the acquisition date to the earliest redemption date using the effective interest method.  The Company will record the accretion after the allocation of net income and distributions of cash flow to the noncontrolling interest account balance.
	The following table reflects the activity of the noncontrolling interest—redeemable interest in property partnership in the Company's Fountain Square consolidated joint venture for the nine months ended September 30, 2013 (in thousands):
	Balance at January 1, 2013	$	97,558
	Net loss	(1,523		)
	Distributions	(3,935		)
	Adjustment to reflect redeemable interest at redemption value	6,549
	Balance at September 30, 2013	$	98,649
	Noncontrolling Interest—Redeemable Preferred Units of the Company
	The Preferred Units at September 30, 2013 included 995,997 Series Two Preferred Units, which bear a preferred distribution equal to the greater of (1) the distribution which would have been paid in respect of the Series Two Preferred Unit had such Series Two Preferred Unit been converted into an OP Unit (including both regular and special distributions) or (2) 6.00% per annum on a liquidation preference of $50.00 per unit, and are convertible into OP Units at a rate of $38.10 per Preferred Unit (1.312336 OP Units for each Preferred Unit). The holders of Series Two Preferred Units have the right to require the Company to redeem all of the outstanding units for cash at the redemption price of $50.00 per unit on May 12, 2014. The holders also had the right to have 1,007,662 Series Two Preferred Units (or such lesser amount that may have been outstanding) redeemed for cash on each of May 12, 2009, May 12, 2010, May 12, 2011, May 14, 2012 and May 14, 2013, although no holder exercised such right. In May 2014, the Company's general partner also has the right, subject to certain conditions, to call for redemption all of the outstanding Series Two Preferred Units for cash or to convert into OP Units any Series Two Preferred Units that have not been previously redeemed. In the event the Company's general partner calls the Series Two Preferred Units for redemption, the holders shall have the right to convert the Series Two Preferred Units into OP Units.
	On February 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit. On May 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit. On August 15, 2013, the Company paid a distribution on its outstanding Series Two Preferred Units of $0.85302 per unit.
	Due to the redemption option and the conversion option existing outside the control of the Company, the Series Two Preferred Units are not included in Partners’ Capital and are reflected in the Consolidated Balance Sheets at an amount equivalent to the value of such units had such units been redeemed at September 30, 2013. The value of the Series Two Preferred Units, assuming all of such units had been converted and then redeemed at September 30, 2013, was approximately $139.7 million based on the closing price of Boston Properties, Inc.’s common stock of $106.90 per share on that date.
	The Preferred Units at September 30, 2013 also included 360,126 Series Four Preferred Units, which bear a preferred distribution equal to 2.00% per annum on a liquidation preference of $50.00 per unit and are not convertible into OP Units. In order to secure the performance of certain obligations by the holders, such Series Four Preferred Units are subject to forfeiture pursuant to the terms of a pledge agreement. The holders of Series Four Preferred Units have the right, at certain times and subject to certain conditions set forth in the Certificate of Designations establishing the rights, limitations and preferences of the Series Four Preferred Units, to require the Company to redeem all of their units for cash at the redemption price of $50.00 per unit. The Company also has the right, at certain times and subject to certain conditions, to redeem all of the Series Four Preferred Units for cash at the redemption price of $50.00 per unit. The Series Four Preferred Units that are subject to the security interest under the pledge agreement may not be redeemed until and unless such security interest is released. The Company's first right to redeem the Series Four Preferred Units was a 30-day period beginning on August 29, 2013. Due to the holders' redemption option existing outside the control of the Company, the Series Four Preferred Units are not included in Partners' Capital in the Company's Consolidated Balance Sheets. On August 29, 2013, Boston Properties, Inc., in its capacity as the general partner of the Company, redeemed approximately 861,400 Series Four Preferred Units for cash at the redemption price of $50.00 per unit plus accrued and unpaid distributions through the redemption date.
	On February 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. On May 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit. On August 15, 2013, the Company paid a distribution on its outstanding Series Four Preferred Units of $0.25 per unit.
	The following table reflects the activity of the noncontrolling interests—redeemable preferred units of the Company for the nine months ended September 30, 2013 and 2012 (in thousands):
	Balance at January 1, 2013	$	199,378
	Net income	3,385
	Distributions	(3,385		)
	Redemption of redeemable preferred units (Series Four Preferred Units)	(43,070		)
	Reallocation of partnership interest	1,425
	Balance at September 30, 2013	$	157,733
	Balance at January 1, 2012	$	145,484
	Issuance of redeemable preferred units (Series Four Preferred Units)	79,405
	Net income	2,440
	Distributions	(2,440		)
	Redemption of redeemable preferred units (Series Four Preferred Units)	(18,329		)
	Reallocation of partnership interest (1)	(908		)
	Balance at September 30, 2012	$	205,652
	(1) Includes the conversion of 117,407 Series Two Preferred Units into 153,605 OP Units during the nine months ended September 30, 2012.
	Noncontrolling Interest—Common Units of the Company
	During the nine months ended September 30, 2013, 336,935 OP Units were presented by the holders for redemption (including 19,589 OP Units issued upon conversion of LTIP Units) and were redeemed by Boston Properties, Inc. in exchange for an equal number of shares of Common Stock.
	At September 30, 2013, the Company had outstanding 396,500 2011 OPP Units, 396,150 2012 OPP Units and 316,325 2013 MYLTIP Units. Prior to the measurement date (January 31, 2014 for 2011 OPP Units, February 6, 2015 for 2012 OPP Units and February 4, 2016 for 2013 MYLTIP Units), holders of OPP Units and 2013 MYLTIP Units will be entitled to receive per unit distributions equal to one-tenth (10%) of the regular quarterly distributions payable on an OP Unit, but will not be entitled to receive any special distributions. After the measurement date, the number of OPP Units and 2013 MYLTIP Units, both vested and unvested, that OPP and 2013 MYLTIP award recipients have earned, if any, based on the establishment of a performance pool, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on an OP Unit.
	On January 29, 2013, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units and 2012 OPP Units in the amount of $0.065 per unit, to holders of record as of the close of business on December 31, 2012. On April 30, 2013, the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on March 29, 2013. On July 31, 2013 the Company paid a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit, and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, to holders of record as of the close of business on June 28, 2013. On September 18, 2013, Boston Properties, Inc., as general partner of the Company, declared a distribution on the OP Units and LTIP Units in the amount of $0.65 per unit and a distribution on the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units in the amount of $0.065 per unit, in each case payable on October 31, 2013 to holders of record as of the close of business on September 30, 2013.
	The following table reflects the activity of the noncontrolling interests—redeemable common units for the nine months ended September 30, 2013 and 2012 (in thousands):
	Balance at January 1, 2013	$	1,836,522
	Contributions	26,384
	Net income	74,395
	Distributions	(33,956		)
	Conversion of redeemable partnership units	(10,406		)
	Unearned compensation	(2,262		)
	Accumulated other comprehensive loss	189
	Adjustment to reflect redeemable partnership units at redemption value	(52,323		)
	Balance at September 30, 2013	$	1,838,543
	Balance at January 1, 2012	$	1,809,119
	Contributions	24,653
	Net income	27,386
	Distributions	(30,100		)
	Conversion of redeemable partnership units	(11,236		)
	Unearned compensation	(4,832		)
	Accumulated other comprehensive loss	208
	Adjustment to reflect redeemable partnership units at redemption value	187,038
	Balance at September 30, 2012	$	2,002,236
	Pursuant to the Company’s Partnership Agreement, certain limited partners in the Company have the right to redeem all or any portion of their interest for cash from the Company. However, Boston Properties, Inc. may elect to acquire the limited partner’s interest by issuing its Common Stock in exchange for the interest. The amount of cash to be paid to the limited partner if the redemption right is exercised and Boston Properties, Inc. does not elect to issue its Common Stock is based on the trading price of Boston Properties, Inc.’s common stock at that time. Due to the redemption option existing outside the control of the Company, such limited partners’ units are not included in Partners’ Capital. The value of the OP Units not owned by Boston Properties, Inc. (including LTIP Units assuming that all conditions had been met for the conversion thereof), assuming all of such units had been redeemed at September 30, 2013 was approximately $1.8 billion based on the closing price of Boston Properties, Inc.’s common stock of $106.90 per share.
	Noncontrolling Interests—Property Partnerships
	The noncontrolling interests in property partnerships consist of the outside equity interests in ventures that are consolidated with the financial results of the Company because the Company exercises control over the entities that own the properties. The equity interests in these ventures that are not owned by the Company, totaling approximately $481.6 million at September 30, 2013 and approximately $(2.0) million at December 31, 2012, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.
	On February 7, 2013, the partner in the Company's Transbay Tower joint venture issued a notice that it was electing under the joint venture agreement to reduce its nominal ownership interest in the venture from 50% to 5%. On February 26, 2013, the Company issued a notice to the partner electing to proceed with the venture on that basis. As a result, the Company has a 95% nominal interest in and is consolidating the joint venture. Under the joint venture agreement, if certain return thresholds are achieved the partner will be entitled to an additional promoted interest. Also, under the agreement, (1) the partner has the right to cause the Company to purchase the partner's interest after the defined stabilization date and (2) the Company has the right to acquire the partner's interest on the third anniversary of the stabilization date, in each case at an agreed upon purchase price or appraised value. On March 26, 2013, the consolidated joint venture completed the acquisition of a land parcel in San Francisco, California which will support a 60-story, 1.4 million square foot office tower known as Transbay Tower. The purchase price for the land was approximately $192.0 million. The joint venture has commenced construction of the initial phase of the development consisting of building the project to grade (See Note 3).
	On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue(the General Motors Building) in New York City) transferred all of their interests in the joint venture to third parties. In connection with the transfer, the Company and its new joint venture partners modified the Company's relative decision making authority and consent rights with respect to the joint venture's assets and operations. These changes resulted in the Company having sufficient financial and operating control over 767 Venture, LLC such that the Company now accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting. Upon consolidation, the Company recognized the new joint venture partners' aggregate 40% equity interest at its aggregate fair value of approximately $480.9 million within Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets (See Notes 3 and 4).
	The following table reflects the activity of the noncontrolling interests in property partnerships for the nine months ended September 30, 2013 and 2012 (in thousands):
	Balance at January 1, 2013	$	(1,964	)
	Fair value of capital recorded upon consolidation	480,861
	Capital contributions	10,932
Net income (loss)	(5,950		)
Distributions	(2,250		)
Balance at September 30, 2013	$	481,629
Balance at January 1, 2012	$	(1,063	)
Net income	1,461
Distributions	(2,250		)
Balance at September 30, 2012	$	(1,852	)

Partners_Capital

Partners' Capital	9 Months Ended
	Sep. 30, 2013
Partners' Capital [Abstract]	'
Partners' Capital	'
	Partners’ Capital
	As of September 30, 2013, Boston Properties, Inc. owned 1,695,893 general partnership units and 150,694,702 limited partnership units.
	As of September 30, 2013, approximately $305.3 million remained available for issuance under Boston Properties, Inc.'s $600 million “at the market” stock offering program.
	During the nine months ended September 30, 2013, Boston Properties, Inc. acquired 336,935 OP Units in connection with the redemption of an equal number of redeemable OP Units from third parties.
	On January 29, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on December 31, 2012. On April 30, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on March 29, 2013. On July 31, 2013, the Company paid a distribution in the amount of $0.65 per OP Unit to unitholders of record as of the close of business on June 28, 2013. On September 18, 2013, Boston Properties, Inc.'s Board of Directors declared a distribution of $0.65 per OP Unit payable on October 31, 2013 to unitholders of record as of the close of business on September 30, 2013.
	On March 27, 2013, Boston Properties, Inc. completed an underwritten public offering of 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) of its newly designated 5.25% Series B Cumulative Redeemable Preferred Stock, at a price of $2,500.00 per share ($25.00 per depositary share). The net proceeds from this offering were approximately $193.6 million, after deducting the underwriting discount and transaction expenses. Boston Properties, Inc. contributed the net proceeds to the Company in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock. Boston Properties, Inc. will pay cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share. Boston Properties, Inc. may not redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of Boston Properties, Inc.'s REIT status. On or after March 27, 2018, Boston Properties, Inc., at its option, may redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ($25.00 per depositary share), plus all accrued and unpaid dividends. The Series B Preferred Stock is not redeemable by the holders, has no maturity date and is not convertible into any other security of Boston Properties, Inc., the Company or its affiliates.
	On May 15, 2013, the Company paid a distribution on its outstanding Series B Preferred Units of $32.8125 per unit. On August 15, 2013, the Company paid a distribution on its outstanding Series B Preferred Units of $32.8125 per unit. On September 18, 2013, Boston Properties, Inc.'s Board of Directors declared a distribution of $32.8125 per unit of Series B Preferred Units payable on November 15, 2013 to shareholders of record as of the close of business on November 5, 2013.
	During the nine months ended September 30, 2013, Boston Properties, Inc. issued 419,116 shares of Common Stock in connection with the exchange by holders of the Company's 3.75% Exchangeable Senior Notes due 2036 (See Note 7). The Company issued 419,116 OP Units to Boston Properties, Inc.

Earnings_Per_Common_Unit

Earnings Per Common Unit	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings Per Common Unit	'
	Earnings Per Common Unit
	The following table provides a reconciliation of both the net income attributable to Boston Properties Limited Partnership and the number of common units used in the computation of basic earnings per common unit, which is calculated by dividing net income attributable to Boston Properties Limited Partnership by the weighted-average number of common units outstanding during the period. The terms of the Series Two Preferred Units enable the holders to obtain OP Units of Company and as a result these are considered participating securities. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc. and the Company’s LTIP Units, OPP Units and 2013 MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic earnings per common unit using the two-class method. Participating securities are included in the computation of diluted earnings per common unit using the if-converted method if the impact is dilutive.  Because the OPP Units and 2013 MYLTIP Units require Boston Properties, Inc. to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, the Company excludes such units from the diluted earnings per common unit calculation. Other potentially dilutive common units and the related impact on earnings are considered when calculating diluted earnings per common unit. Included in the number of units (the denominator) below are approximately 16,829,000 and 17,660,000 redeemable common units for the three months ended September 30, 2013 and 2012, respectively, and approximately 16,975,000 and 17,694,000 redeemable common units for the nine months ended September 30, 2013 and 2012, respectively.
		For the three months ended September 30, 2013
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	84,497		169,236	$	0.5
	Discontinued operations attributable to Boston Properties Limited Partnership	89,643			—	0.53
	Allocation of undistributed earnings to participating securities	(651		)	—	—
	Net income attributable to Boston Properties Limited Partnership	$	173,489		169,236	$	1.03
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			285	(0.01		)
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	173,489		169,521	$	1.02
		For the three months ended September 30, 2012
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	64,684		168,461	$	0.38
	Discontinued operations attributable to Boston Properties Limited Partnership	1,550			—	0.01
	Net income attributable to Boston Properties Limited Partnership	$	66,234		168,461	$	0.39
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			1,182	—
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	66,234		169,643	$	0.39
		For the nine months ended September 30, 2013
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	628,206		168,975	$	3.72
	Discontinued operations attributable to Boston Properties Limited Partnership	112,046			—	0.66
	Allocation of undistributed earnings to participating securities	(4,183		)	—	(0.02		)
	Net income attributable to Boston Properties Limited Partnership	$	736,069		168,975	$	4.36
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			381	(0.01		)
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	736,069		169,356	$	4.35
		For the nine months ended September 30, 2012
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	215,296		167,517	$	1.29
	Discontinued operations attributable to Boston Properties Limited Partnership	44,041			—	0.26
	Net income attributable to Boston Properties Limited Partnership	$	259,337		167,517	$	1.55
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			655	(0.01		)
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	259,337		168,172	$	1.54

Stock_Option_and_Incentive_Pla

Stock Option and Incentive Plan	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Stock Option and Incentive Plan	'
	Stock Option and Incentive Plan
	On January 28, 2013, Boston Properties, Inc.'s Compensation Committee approved multi-year long-term incentive program (MYLTIP) awards under Boston Properties, Inc.'s 2012 Stock Option and Incentive Plan (the "2012 Plan") to officers and employees of Boston Properties, Inc. MYLTIP awards utilize total return to shareholders ("TRS") over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.'s TRS relative to (i) the Cohen & Steers Realty Majors Portfolio Index (50% weight) and (ii) the NAREIT Office Index adjusted to exclude Boston Properties, Inc. (50% weight). Earned awards will range from zero to a maximum of approximately $30.7 million depending on Boston Properties, Inc.'s TRS relative to the two indices, with four tiers (threshold: approximately $5.1 million; target: approximately $10.2 million; high: approximately $20.5 million; exceptional: approximately $30.7 million) and linear interpolation between tiers. Earned awards measured on the basis of relative TRS performance are subject to an absolute TRS component in the form of relatively simple modifiers that (A) reduce the level of earned awards in the event Boston Properties, Inc.'s annualized TRS is less than 2% and (B) cause some awards to be earned in the event Boston Properties, Inc.'s annualized TRS is more than 10% even though on a relative basis alone Boston Properties, Inc.'s TRS would not result in any earned awards.
	Earned awards (if any) will vest 25% on February 4, 2016, 25% on February 4, 2017 and 50% on February 4, 2018, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 4, 2016, earned awards will be calculated based on TRS performance up to the date of the change of control. MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units.
	On March 11, 2013, Boston Properties, Inc. announced that Owen D. Thomas would succeed Mortimer B. Zuckerman as Boston Properties, Inc.'s Chief Executive Officer, effective April 2, 2013. On April 2, 2013, the Company issued 24,231 LTIP units, 38,926 2013 MYLTIP Units and 50,847 non-qualified stock options under the 2012 Plan to Mr. Thomas, pursuant to his employment agreement. Mr. Zuckerman will continue to serve as Executive Chairman for a transition period and thereafter is expected to continue to serve as the Non-Executive Chairman of the Board of Boston Properties, Inc.  In connection with succession planning, Boston Properties, Inc. and Mr. Zuckerman entered into a Transition Benefits Agreement. If Mr. Zuckerman remains employed by Boston Properties, Inc. through July 1, 2014, he will be entitled to receive on January 1, 2015 a lump sum cash payment of $6.7 million and an equity award with a targeted value of approximately $11.1 million. The cash payment and equity award vest one-third on each of March 10, 2013, October 1, 2013 and July 1, 2014, subject to acceleration in certain circumstances. As a result, Boston Properties, Inc. recognized approximately $2.6 million and $11.8 million of compensation expense during the three and nine months ended September 30, 2013, respectively. In addition, the agreement provides that if Mr. Zuckerman terminates his employment with Boston Properties, Inc. for any reason, voluntarily or involuntarily, he will become fully vested in any outstanding equity awards with time-based vesting. As a result, during the nine months ended September 30, 2013, Boston Properties, Inc. accelerated the remaining approximately $12.9 million of stock-based compensation expense associated with Mr. Zuckerman's unvested long-term equity awards.
	Under the Financial Accounting Standards Board's Accounting Standards Codification (“ASC”) 718 “Compensation-Stock Compensation” the MYLTIP awards granted to employees in February 2013 and granted to Mr. Thomas in April 2013 have an aggregate value of approximately $9.2 million, which amount will generally be amortized into earnings over the five-year plan period under the graded vesting method.
	During the nine months ended September 30, 2013, Boston Properties, Inc. issued 36,730 shares of restricted common stock and 252,220 non-qualified stock options and the Company issued 184,733 LTIP Units and 318,926 2013 MYLTIP Units to employees and non-employee directors under the 2012 Plan, including the amounts issued to Mr. Thomas pursuant to his employment agreement, as discussed above. Employees and directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit, OPP Unit and 2013 MYLTIP Unit. An LTIP Unit is generally the economic equivalent of a share of restricted stock in Boston Properties, Inc. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets. Grants of restricted stock and LTIP Units to employees vest in four equal annual installments. Restricted stock is measured at fair value on the date of grant based on the number of shares granted, as adjusted for forfeitures, and the closing price of Boston Properties, Inc.’s Common Stock on the date of grant as quoted on the New York Stock Exchange. Such value is recognized as an expense ratably over the corresponding employee service period. The shares of restricted stock granted during the nine months ended September 30, 2013 were valued at approximately $3.9 million ($105.30 per share weighted-average). The non-qualified stock options granted to employees in February 2013 had a weighted-average fair value on the date of grant of $18.46 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 6.0 years, a risk-free interest rate of 1.11%, an expected price volatility of 26% and an expected dividend yield of 3%. The exercise price of the options is $105.10, which was the closing price of Boston Properties, Inc.’s common stock on the date of grant. The LTIP Units granted to employees in February 2013 were valued at approximately $14.8 million ($96.33 per unit fair value) using a Monte Carlo simulation method model. The per unit fair value of each LTIP Unit granted was estimated on the date of grant using the following assumptions: an expected life of 5.7 years, a risk-free interest rate of 1.03% and an expected price volatility of 26%. As the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units under the graded vesting attribution method. Under the graded vesting attribution method, each portion of the award that vests at a different date is accounted for as a separate award and recognized over the period appropriate to that portion so that the compensation cost for each portion should be recognized in full by the time that portion vests. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Partners’ Capital in the Consolidated Balance Sheets. Aggregate stock-based compensation expense associated with restricted stock, non-qualified stock options, LTIP Units, 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units was approximately $6.2 million and $6.4 million for the three months ended September 30, 2013 and 2012, respectively, and approximately $38.1 million and $23.8 million for the nine months ended September 30, 2013 and 2012, respectively. For the three and nine months ended September 30, 2013, stock-based compensation expense includes approximately $1.6 million and $20.2 million, respectively, consisting of the acceleration of the expense of Boston Properties, Inc.’s Executive Chairman’s stock-based compensation awards and the stock-based compensation awards associated with his transition benefits agreement related to Boston Properties, Inc.'s succession planning. For the nine months ended September 30, 2012, stock-based compensation expense includes approximately $2.7 million consisting of the acceleration of vesting of Boston Properties, Inc.‘s Chief Operating Officer’s stock-based compensation awards associated with his resignation. At September 30, 2013, there was $20.2 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and $12.7 million of unrecognized compensation expense related to unvested 2011 OPP Units, 2012 OPP Units and 2013 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.8 years.

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Segment Information	'
	Segment Information
	The Company’s segments are based on the Company’s method of internal reporting which classifies its operations by both geographic area and property type. The Company’s segments by geographic area are Boston, New York, Princeton, San Francisco and Washington, DC. Segments by property type include: Class A Office, Office/Technical, Residential and Hotel.
	Asset information by segment is not reported because the Company does not use this measure to assess performance. Therefore, depreciation and amortization expense is not allocated among segments. Interest and other income, development and management services, general and administrative expenses, transaction costs, impairment loss, interest expense, depreciation and amortization expense, gains from investments in securities, gains (losses) from early extinguishments of debt, gains on consolidation of joint ventures, income from unconsolidated joint ventures, discontinued operations and noncontrolling interests are not included in Net Operating Income as internal reporting addresses these items on a corporate level.
	Net Operating Income is not a measure of operating results or cash flows from operating activities as measured by accounting principles generally accepted in the United States of America, and it is not indicative of cash available to fund cash needs and should not be considered an alternative to cash flows as a measure of liquidity. All companies may not calculate Net Operating Income in the same manner. The Company considers Net Operating Income to be an appropriate supplemental measure to net income because it helps both investors and management to understand the core operations of the Company’s properties.
	We have modified the presentation of expenses to operate our San Francisco and Princeton regional offices to reflect the growing activity in our San Francisco region and to have a consistent presentation across our company. For San Francisco these expenses, which totaled approximately $1.7 million and $1.5 million for the three months ended September 30, 2013 and 2012, respectively, and approximately $4.8 million and $4.4 million for the nine months ended September 30, 2013 and 2012, respectively, and for Princeton these expenses, which totaled approximately $0.3 million and $0.4 million for the three months ended September 30, 2013 and 2012, respectively, and approximately $1.3 million and $1.4 million for the nine months ended September 30, 2013 and 2012, respectively, were previously included in Rental Operating Expenses and are now included in General and Administrative Expenses for all periods presented.
	On May 31, 2013, the Company's two joint venture partners in 767 Venture, LLC (the entity that owns 767 Fifth Avenue (the General Motors Building) located in New York City) transferred all of their interests in the joint venture to third parties. (See Note 3). Effective as of May 31, 2013, the Company accounts for the assets, liabilities and operations of 767 Venture, LLC on a consolidated basis in its financial statements instead of under the equity method of accounting Upon consolidation, the operations for this building will be included in the New York region.
	Information by geographic area and property type (dollars in thousands):
	For the three months ended September 30, 2013:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	171,228		$	198,450		$	15,636			$	53,841			$	97,925		$	537,080
	Office/Technical	5,662			—			—				5,839				3,877			15,378
	Residential	1,125			—			—				—				4,368			5,493
	Hotel	10,652			—			—				—				—			10,652
	Total	188,667			198,450			15,636				59,680				106,170			568,603
	% of Grand Totals	33.18		%	34.9		%	2.75		%		10.5		%		18.67		%	100		%
	Rental Expenses:
	Class A Office	67,798			66,322			7,033				20,006				32,170			193,329
	Office/Technical	1,763			—			—				1,287				1,064			4,114
	Residential	466			—			—				—				2,441			2,907
	Hotel	6,580			—			—				—				—			6,580
	Total	76,607			66,322			7,033				21,293				35,675			206,930
	% of Grand Totals	37.02		%	32.05		%	3.4		%		10.29		%		17.24		%	100		%
	Net operating income	$	112,060		$	132,128		$	8,603			$	38,387			$	70,495		$	361,673
	% of Grand Totals	30.98		%	36.53		%	2.38		%		10.62		%		19.49		%	100		%
	For the three months ended September 30, 2012:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	161,479		$	120,270		$	15,234			$	52,585			$	84,447		$	434,015
	Office/Technical	5,539			—			—				148				4,099			9,786
	Residential	995			—			—				—				4,501			5,496
	Hotel	9,359			—			—				—				—			9,359
	Total	177,372			120,270			15,234				52,733				93,047			458,656
	% of Grand Totals	38.67		%	26.22		%	3.32		%		11.5		%		20.29		%	100		%
	Rental Expenses:
	Class A Office	65,261			41,088			6,790				19,530				27,419			160,088
	Office/Technical	1,758			—			—				52				941			2,751
	Residential	490			—			—				—				2,364			2,854
	Hotel	6,886			—			—				—				—			6,886
	Total	74,395			41,088			6,790				19,582				30,724			172,579
	% of Grand Totals	43.11		%	23.81		%	3.93		%		11.35		%		17.8		%	100		%
	Net operating income	$	102,977		$	79,182		$	8,444			$	33,151			$	62,323		$	286,077
	% of Grand Totals	36		%	27.68		%	2.95		%		11.59		%		21.78		%	100		%
	For the nine months ended September 30, 2013:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	497,584		$	463,851		$	46,916			$	159,843			$	289,831		$	1,458,025
	Office/Technical	16,853			—			—				11,317				11,951			40,121
	Residential	3,257			—			—				—				13,298			16,555
	Hotel	30,061			—			—				—				—			30,061
	Total	547,755			463,851			46,916				171,160				315,080			1,544,762
	% of Grand Totals	35.46		%	30.02		%	3.04		%		11.08		%		20.4		%	100		%
	Rental Expenses:
	Class A Office	196,710			156,414			21,386				58,036				95,485			528,031
	Office/Technical	5,177			—			—				2,439				3,095			10,711
	Residential	1,316			—			—				—				7,154			8,470
	Hotel	20,959			—			—				—				—			20,959
	Total	224,162			156,414			21,386				60,475				105,734			568,171
	% of Grand Totals	39.45		%	27.53		%	3.77		%		10.64		%		18.61		%	100		%
	Net operating income	$	323,593		$	307,437		$	25,530			$	110,685			$	209,346		$	976,591
% of Grand Totals	33.14		%	31.48		%	2.61		%		11.33		%		21.44		%	100		%
For the nine months ended September 30, 2012:
	Boston			New York			Princeton				San				Washington,			Total
											Francisco				DC
Rental Revenue:
Class A Office	$	460,127		$	360,515		$	45,701			$	155,353			$	258,311		$	1,280,007
Office/Technical	16,882			—			—				344				12,245			29,471
Residential	2,891			—			—				—				12,122			15,013
Hotel	26,224			—			—				—				—			26,224
Total	506,124			360,515			45,701				155,697				282,678			1,350,715
% of Grand Totals	37.47		%	26.69		%	3.38		%		11.53		%		20.93		%	100		%
Rental Expenses:
Class A Office	183,601			118,531			20,889				56,496				81,613			461,130
Office/Technical	4,910			—			—				114				2,952			7,976
Residential	1,247			—			—				—				6,896			8,143
Hotel	19,601			—			—				—				—			19,601
Total	209,359			118,531			20,889				56,610				91,461			496,850
% of Grand Totals	42.14		%	23.86		%	4.2		%		11.39		%		18.41		%	100		%
Net operating income	$	296,765		$	241,984		$	24,812			$	99,087			$	191,217		$	853,865
% of Grand Totals	34.76		%	28.34		%	2.91		%		11.6		%		22.39		%	100		%
The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership:
	Three months ended						Nine months ended September 30,
	September 30,
	2013			2012			2013					2012
Net Operating Income	$	361,673		$	286,077		$	976,591				$	853,865
Add:
Development and management services income	5,479			8,024			22,072					25,733
Income from unconsolidated joint ventures	14,736			9,217			72,240					42,129
Gains on consolidation of joint ventures	(1,810		)	—			385,991					—
Interest and other income	3,879			4,001			6,646					8,029
Gains from investments in securities	956			587			1,872					1,202
Gains (losses) from early extinguishments of debt	(30		)	(5,494		)	122					(4,453		)
Income from discontinued operations	1,078			1,550			5,597			—		5,596
Gains on sales of real estate from discontinued operations	88,565			—			88,565					38,445
Gain on forgiveness of debt from discontinued operations	—			—			20,736					—
Less:
General and administrative expense	24,841			21,617			94,673					72,208
Transaction costs	766			1,140			1,744					3,252
Depreciation and amortization expense	152,156			108,609			402,892					323,680
Interest expense	122,173			105,030			325,746					308,168
Impairment loss	—			—			4,401					—
Impairment loss from discontinued operations	—			—			2,852					—
Noncontrolling interest in property partnerships	(3,279		)	458			(924		)			1,461
Noncontrolling interest—redeemable preferred units	3,729			874			8,796					2,440
Net income attributable to Boston Properties Limited Partnership	$	174,140		$	66,234		$	740,252				$	259,337

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	On October 9, 2013, the Company completed the sale of a 45% ownership interest in its Times Square Tower property for a gross sale price of approximately $684.0 million in cash. Net cash proceeds totaled approximately $673.4 million, after the payment of transaction costs. In connection with the sale, the Company formed a joint venture with the buyer and will provide customary property management and leasing services to the joint venture. Times Square Tower is an approximately 1,246,000 net rentable square foot Class A office tower located in New York City. The Company will continue to account for the property on a consolidated basis in its financial statements and as a result will account for the transaction as an equity transaction with no gain on sale recognized in its consolidated statements of operations.
	On October 21, 2013, approximately 329,881 Series Two Preferred Units of the Company were converted by the holder thereof into 432,914 OP Units. The OP Units were subsequently presented by the holders for redemption and were redeemed by Boston Properties, Inc., as general partner of the Company, on October 29, 2013 in exchange for an equal number of shares of Common Stock.
	On October 29, 2013, the Company entered into a lease agreement as landlord with a third-party tenant for a build-to-suit project with approximately 130,000 net rentable square feet of Class A office space located in Princeton, New Jersey.
	On October 29, 2013, a joint venture in which the Company has a 50% interest exercised an option to extend the maturity date to November 17, 2014 of the construction financing collateralized by its Annapolis Junction Building Six property. The construction financing totaling approximately $14.0 million bears interest at a variable rate equal to LIBOR plus 1.65% per annum and was scheduled to mature on November 17, 2013. Annapolis Junction Building Six is a Class A office property with approximately 119,000 net rentable square feet located in Annapolis, Maryland.

Basis_Of_Presentation_And_Summ1

Basis Of Presentation And Summary Of Significant Accounting Policies Recent Accounting Pronouncement (Policies)	9 Months Ended
	Sep. 30, 2013
Recent Accounting Pronouncement [Abstract]	'
Recent Accounting Pronouncement [Policy Text Block]	'
	Recent Accounting Pronouncements
	In February 2013, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2013-02, "Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income" (“ASU No. 2013-02”). ASU No. 2013-02 requires an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income, but only if the amount reclassified is required to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures that provide additional detail about those amounts. ASU No. 2013-02 is effective prospectively for reporting periods beginning after December 15, 2012. The Company’s adoption of ASU No. 2013-02 did not have a material impact on its consolidated financial statements.

Basis_Of_Presentation_And_Summ2

Basis Of Presentation And Summary Of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Revision of prior period amounts for Montvale Center [Table Text Block]	'
	The table below reflects selected information for the Company for the three and nine months ended September 30, 2012. The servicer of the non-recourse mortgage loan in the amount of $25.0 million collateralized by the Company's Montvale Center property located in Gaithersburg, Maryland foreclosed on the property on January 31, 2012. As a result of the foreclosure, the Company recognized a gain on forgiveness of debt during the nine months ended September 30, 2012 totaling approximately $18.4 million. Due to a procedural error of the trustee, the foreclosure sale was subsequently dismissed by the applicable court prior to ratification. As a result, the Company, as part of its Form 10-K for the fiscal year ended December 31, 2012, revised its financial statements to (1) properly reflect the property and related mortgage debt on its consolidated balance sheet at December 31, 2012, (2) reverse the gain on forgiveness of debt during the nine months ended September 30, 2012 and (3) recognize the operating activity from the property for the three and nine months ended September 30, 2012. On February 20, 2013, the subsequent foreclosure sale of Montvale Center was ratified by the court. As a result of the ratification, the mortgage loan totaling $25.0 million was extinguished and the related obligations were satisfied with the transfer of the real estate resulting in the recognition of a gain on forgiveness of debt totaling approximately $20.7 million during the nine months ended September 30, 2013 (See Note 3). As a result, for the three and nine months ended September 30, 2012, the activity for Montvale Center has been reclassified to discontinued operations in the consolidated statements of operations. In addition, operating results have been reclassified for the three and nine months ended September 30, 2012 as a result of the discontinued operations presentation of (1) the Company's Bedford Business Park properties which were sold on May 17, 2012, (2) the Company's 303 Almaden Boulevard property which was sold on June 28, 2013 (See Note 3) and (3) the Company's 1301 New York Avenue property which was sold on August 22, 2013 (See Note 3).
			For the three months ended September 30, 2012							For the nine months ended September 30, 2012
			As Reported				As Revised			As Reported				As Revised
			(in thousands, except for per unit amounts)
	Total revenue		$	470,904			$	466,680		$	1,389,028			$	1,376,448
	Income from continuing operations		$	68,147			$	66,016		$	225,430			$	219,197
	Discontinued operations		$	—			$	1,550		$	57,690			$	44,041
	Net income attributable to Boston Properties Limited Partnership		$	66,815			$	66,234		$	279,219			$	259,337
	Income attributable to Boston Properties Limited Partnership common unitholders per unit—basic		$	0.4			$	0.39		$	1.67			$	1.55
	Income attributable to Boston Properties Limited Partnership common unitholders per unit—diluted		$	0.39			$	0.39		$	1.66			$	1.54
Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value	'
	The following table presents the aggregate carrying value of the Company’s indebtedness and the Company’s corresponding estimate of fair value as of September 30, 2013 and December 31, 2012 (in thousands):
		September 30, 2013							December 31, 2012
		Carrying				Estimated			Carrying				Estimated
		Amount				Fair Value			Amount				Fair Value
	Mortgage notes payable	$	4,468,069			$	4,592,273		$	3,102,485			$	3,256,940
	Mezzanine notes payable	311,340				311,366			—				—
	Unsecured senior notes	5,835,424				6,065,723			4,639,528				5,162,486
	Unsecured exchangeable senior notes	739,536			-1	768,019			1,170,356			-1	1,278,554
	Total	$	11,354,369			$	11,737,381		$	8,912,369			$	9,697,980
	_______________
	-1	Includes the net adjustment for the equity component allocation totaling approximately $7.4 million and $25.5 million at September 30, 2013 and December 31, 2012, respectively.

Real_Estate_Activity_During_th1

Real Estate Activity During the Nine Months Ended September 30, 2013 (Tables)	9 Months Ended
	Sep. 30, 2013
Business Acquisition [Line Items]	'
Business Acquisition, Pro Forma Information [Table Text Block]	'
	Pro Forma (Unaudited)	Nine Months Ended September 30,
	(in thousands, except per unit data)	2013				2012
	Total revenue	$	1,688,393			$	1,602,949
	Income from continuing operations	$	234,784			$	573,170
	Net income attributable to Boston Properties Limited Partnership	$	351,549			$	633,626
	Basic earnings per unit:
	Net income per unit attributable to Boston Properties Limited Partnership	$	2.08			$	3.76
	Diluted earnings per unit:
	Net income per unit attributable to Boston Properties Limited Partnership	$	2.07			$	3.75
Summary of the Discontinued Operations Related To Montvale Center , 303 Almaden Blvd, 1301 New York Avenue and Bedford Business Park	'
	The following table summarizes the income from discontinued operations related to 1301 New York Avenue, Montvale Center and 303 Almaden Boulevard and the related gain on sale of real estate, gain on forgiveness of debt and impairment loss for the three and nine months ended September 30, 2013 and 2012 and the gain on sale of real estate and income from discontinued operations for the nine months ended September 30, 2012 related to the Company's Bedford Business Park properties which were sold on May 17, 2012:
		For the three months ended September 30,							For the nine months ended September 30,
		2013				2012			2013			2012
		(in thousands)
	Total revenue	$	1,511			$	4,882		$	10,469		$	17,940
	Expenses
	Operating	433				1,781			3,447			6,725
	Depreciation and amortization	—				901			1,065			3,675
	Total expenses	433				2,682			4,512			10,400
	Operating income	1,078				2,200			5,957			7,540
	Other expense
	Interest expense	—				(650		)	(360		)	(1,944		)
	Income from discontinued operations	$	1,078			$	1,550		$	5,597		$	5,596
	Gains on sales of real estate from discontinued operations	$	88,565			$	—		$	88,565		$	38,445
	Gain on forgiveness of debt from discontinued operations	$	—			$	—		$	20,736		$	—
	Impairment loss from discontinued operations	$	—			$	—		$	(2,852	)	$	—
Mountain View Research And Technology Parks [Member]	'
Business Acquisition [Line Items]	'
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	'
	Land	$	126,521
	Building and improvements	82,451
	Tenant improvements	7,326
	In-place lease intangibles	23,279
	Above-market rents	843
	Below-market rents	(7,336		)
	Net assets acquired	$	233,084
767 Fifth Avenue (The GM Building) [Member]	'
Business Acquisition [Line Items]	'
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	'
	Real estate and related intangibles recorded upon consolidation
	Land	$	1,796,252
	Building and improvements	1,447,446
	Tenant improvements	85,208
	In-place lease intangibles	357,781
	Above market rents	101,897
	Below market rents	(239,641		)
	Above market assumed debt adjustments	(192,943		)
		$	3,356,000
	Debt recorded upon consolidation
	Mortgage notes payable	$	(1,300,000	)
	Mezzanine notes payable	(306,000		)
	Related party notes payable	(450,000		)	-1
		$	(2,056,000	)
	Working capital recorded upon consolidation
	Cash and cash equivalents	$	79,468
	Cash held in escrows	2,403
	Tenant and other receivables	7,104
	Prepaid expenses and other assets	4,269
	Accounts payable and accrued expenses	(2,418		)
	Accrued interest payable	(182,369		)	-2
	Other liabilities	(6,304		)
		$	(97,847	)
	Noncontrolling interest recorded upon consolidation
	Noncontrolling interests	$	(520,000	)
	Noncontrolling interests - working capital	39,139
		$	(480,861	)
	Net assets recorded upon consolidation	$	721,292
	_______________
	(1) The Company's partner loans totaling $270.0 million eliminates in consolidation.
	(2) The Company's share of the accrued interest payable on the partner loans totaling approximately $105.5 million eliminates in consolidation.

Investments_in_Unconsolidated_1

Investments in Unconsolidated Joint Ventures (Tables)	9 Months Ended
	Sep. 30, 2013
Investments In Unconsolidated Joint Ventures [Abstract]	'
Investments In Unconsolidated Joint Ventures	'
	The investments in unconsolidated joint ventures consist of the following at September 30, 2013:
	Entity		Properties		Nominal %
					Ownership
	Square 407 Limited Partnership		Market Square North		50	%
	The Metropolitan Square Associates LLC		Metropolitan Square		51	%
	BP/CRF 901 New York Avenue LLC		901 New York Avenue		25	%	(1)
	WP Project Developer LLC		Wisconsin Place Land and Infrastructure		33.3	%	(2)
	RBP Joint Venture LLC		N/A		50	%	(3)
	Boston Properties Office Value-Added Fund, L.P.		N/A		39.5	%	-4
	Annapolis Junction NFM, LLC		Annapolis Junction		50	%	(5)
	2 GCT Venture LLC		N/A		60	%	(6)
	540 Madison Venture LLC		540 Madison Avenue		60	%
	125 West 55th Street Venture LLC		N/A		60	%	-7
	500 North Capitol LLC		500 North Capitol Street, NW		30	%
	_______________
	-1	The Company’s economic ownership can increase based on the achievement of certain return thresholds.
	-2	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land and infrastructure of the project.
	-3	Eighth Avenue and 46th Street was sold on July 19, 2013.
	-4	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of September 30, 2013, the investment is comprised of undistributed cash.
	-5	Comprised of two buildings, one building under construction and two undeveloped land parcels.
	-6	Two Grand Central Tower was sold on October 25, 2011. As of September 30, 2013, the investment is comprised of undistributed cash.
	-7	125 West 55th Street was sold on May 30, 2013. As of September 30, 2013, the investment is comprised of undistributed cash
Balance Sheets Of The Unconsolidated Joint Ventures	'
	The combined summarized balance sheets of the Company's unconsolidated joint ventures are as follows:
		September 30, 2013				December 31,
						2012
		(in thousands)
	ASSETS
	Real estate and development in process, net	$	927,890			$	4,494,971
	Other assets	158,105				673,716
	Total assets	$	1,085,995			$	5,168,687
	LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
	Mortgage and notes payable	$	748,489			$	3,039,922
	Other liabilities	21,183				792,888
	Members’/Partners’ equity	316,323				1,335,877
	Total liabilities and members’/partners’ equity	$	1,085,995			$	5,168,687
	Company’s share of equity	$	157,875			$	787,941
	Basis differentials (1)	(28,837		)		(128,025		)
	Carrying value of the Company’s investments in unconsolidated joint ventures	$	129,038			$	659,916
	_______________
	-1	This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from impairment of investments and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level.
Statements Of Operations Of The Joint Ventures	'
	The combined summarized statements of operations of the Company's unconsolidated joint ventures are as follows:
		For the three months ended September 30,							For the nine months ended September 30,
		2013				2012			2013			2012
		(in thousands)
	Total revenue (1)	$	37,983			$	135,998		$	273,464		$	431,133
	Expenses
	Operating	14,963				42,298			89,826			120,451
	Depreciation and amortization	9,784				39,291			76,202			123,869
	Total expenses	24,747				81,589			166,028			244,320
	Operating income	13,236				54,409			107,436			186,813
	Other income (expense)
	Interest expense	(8,148		)		(56,521		)	(104,436		)	(167,792		)
	Losses from early extinguishments of debt	—				—			(1,677		)	—
	Income (loss) from continuing operations	5,088				(2,112		)	1,323			19,021
	Gains on sales of real estate	12,441				990			14,207			990
	Net income (loss)	$	17,529			$	(1,122	)	$	15,530		$	20,011
	Company’s share of net income (loss)	$	3,149			$	(1,420	)	$	1,974		$	10,591
	Gains on sales of real estate	11,174				—			54,501			—
	Basis differential	413				384			(1,213		)	1,282
	Elimination of inter-entity interest on partner loan	—				10,253			16,978			30,256
	Income from unconsolidated joint ventures	$	14,736			$	9,217		$	72,240		$	42,129
	Gains on consolidation of joint ventures	$	(1,810	)		$	—		$	385,991		$	—
	_______________
	-1	Includes straight-line rent adjustments of $0.6 million and $2.2 million for the three months ended September 30, 2013 and 2012, respectively, and $7.6 million and $9.3 million for the nine months ended September 30, 2013 and 2012, respectively. Includes net below-market rent adjustments of $(0.1) million and $22.1 million for the three months ended September 30, 2013 and 2012, respectively, and $33.9 million and $70.6 million for the nine months ended September 30, 2013 and 2012, respectively. Total revenue for the nine months ended September 30, 2012 includes termination income totaling approximately $19.6 million (of which the Company's share is approximately $11.8 million) related to a lease termination with a tenant at 767 Fifth Avenue (the General Motors Building).

Unsecured_Senior_Notes_Tables

Unsecured Senior Notes (Tables)	9 Months Ended
	Sep. 30, 2013
Unsecured Senior Notes [Abstract]	'
Schedule of Unsecured Senior Notes [Table Text Block]	'
	The following summarizes the unsecured senior notes outstanding as of September 30, 2013 (dollars in thousands):
		Coupon/		Effective		Principal			Maturity Date(2)
		Stated Rate		Rate(1)		Amount
	12 Year Unsecured Senior Notes	5.625	%	5.693	%	$	300,000		April 15, 2015
	12 Year Unsecured Senior Notes	5	%	5.194	%	250,000			June 1, 2015
	10 Year Unsecured Senior Notes	5.875	%	5.967	%	700,000			15-Oct-19
	10 Year Unsecured Senior Notes	5.625	%	5.708	%	700,000			15-Nov-20
	10 Year Unsecured Senior Notes	4.125	%	4.289	%	850,000			15-May-21
	7 Year Unsecured Senior Notes	3.7	%	3.853	%	850,000			November 15, 2018
	11 Year Unsecured Senior Notes	3.85	%	3.954	%	1,000,000			February 1, 2023
	10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
	10.5 Year Unsecured Senior Notes	3.8	%	3.916	%	700,000			February 1, 2024
	Total principal					5,850,000
	Net unamortized discount					(14,576		)
	Total					$	5,835,424
	_______________
	-1	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.
	-2	No principal amounts are due prior to maturity.

Unsecured_Exchangeable_Senior_1

Unsecured Exchangeable Senior Notes (Tables)

9 Months Ended

Sep. 30, 2013

Unsecured Exchangeable Senior Notes [Abstract]

'

Schedule of Unsecured Exchangeable Senior Notes

'

The following summarizes the unsecured exchangeable senior notes outstanding as of September 30, 2013 (dollars in thousands):

Coupon/

Effective

Exchange

Principal

First Optional

Maturity Date

Stated Rate

Rate(1)

Rate

Amount

Redemption Date by the

Company

3.625% Exchangeable Senior Notes

3.625

%

4.037

%

8.5051

-2

$

747,500

N/A

February 15, 2014

Net unamortized discount

(555

)

Adjustment for the equity component allocation, net of accumulated amortization

(7,409

)

Total

$

739,536

_______________

-1

Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs but excluding the effects of the adjustment for the equity component allocation.

-2

The initial exchange rate is 8.5051 shares per $1,000 principal amount of the notes (or an initial exchange price of approximately $117.58 per share of Boston Properties, Inc.’s common stock). In addition, the Company entered into capped call transactions with affiliates of certain of the initial purchasers, which are intended to reduce the potential dilution upon future exchange of the notes. The capped call transactions were intended to increase the effective exchange price to the Company of the notes from $117.58 to approximately $137.17 per share (subject to adjustment), representing an overall effective premium of approximately 40% over the closing price on August 13, 2008 of $97.98 per share of Boston Properties, Inc.’s common stock. The net cost of the capped call transactions was approximately $44.4 million. As of September 30, 2013, the effective exchange price was $134.14 per share.

Noncontrolling_Interests_Table

Noncontrolling Interests (Tables)	9 Months Ended
	Sep. 30, 2013
Noncontrolling Interest [Abstract]	'
Schedule of Redeemable Interest in Property Partnerships [Table Text Block]	'
	he following table reflects the activity of the noncontrolling interest—redeemable interest in property partnership in the Company's Fountain Square consolidated joint venture for the nine months ended September 30, 2013 (in thousands):
	Balance at January 1, 2013	$	97,558
	Net loss	(1,523		)
	Distributions	(3,935		)
	Adjustment to reflect redeemable interest at redemption value	6,549
	Balance at September 30, 2013	$	98,649
Schedule Of Series Two Preferred Units	'
	The following table reflects the activity of the noncontrolling interests—redeemable preferred units of the Company for the nine months ended September 30, 2013 and 2012 (in thousands):
	Balance at January 1, 2013	$	199,378
	Net income	3,385
	Distributions	(3,385		)
	Redemption of redeemable preferred units (Series Four Preferred Units)	(43,070		)
	Reallocation of partnership interest	1,425
	Balance at September 30, 2013	$	157,733
	Balance at January 1, 2012	$	145,484
	Issuance of redeemable preferred units (Series Four Preferred Units)	79,405
	Net income	2,440
	Distributions	(2,440		)
	Redemption of redeemable preferred units (Series Four Preferred Units)	(18,329		)
	Reallocation of partnership interest (1)	(908		)
	Balance at September 30, 2012	$	205,652
	(1) Includes the conversion of 117,407 Series Two Preferred Units into 153,605 OP Units during the nine months ended September 30, 2012.
Noncontrolling Interests-Redeemable Common Units	'
	The following table reflects the activity of the noncontrolling interests—redeemable common units for the nine months ended September 30, 2013 and 2012 (in thousands):
	Balance at January 1, 2013	$	1,836,522
	Contributions	26,384
	Net income	74,395
	Distributions	(33,956		)
	Conversion of redeemable partnership units	(10,406		)
	Unearned compensation	(2,262		)
	Accumulated other comprehensive loss	189
	Adjustment to reflect redeemable partnership units at redemption value	(52,323		)
	Balance at September 30, 2013	$	1,838,543
	Balance at January 1, 2012	$	1,809,119
	Contributions	24,653
	Net income	27,386
	Distributions	(30,100		)
	Conversion of redeemable partnership units	(11,236		)
	Unearned compensation	(4,832		)
	Accumulated other comprehensive loss	208
	Adjustment to reflect redeemable partnership units at redemption value	187,038
	Balance at September 30, 2012	$	2,002,236
Noncontrolling Interests-Property Partnerships	'
	The following table reflects the activity of the noncontrolling interests in property partnerships for the nine months ended September 30, 2013 and 2012 (in thousands):
	Balance at January 1, 2013	$	(1,964	)
	Fair value of capital recorded upon consolidation	480,861
	Capital contributions	10,932
	Net income (loss)	(5,950		)
	Distributions	(2,250		)
	Balance at September 30, 2013	$	481,629
	Balance at January 1, 2012	$	(1,063	)
	Net income	1,461
	Distributions	(2,250		)
	Balance at September 30, 2012	$	(1,852	)

Earnings_Per_Common_Unit_Table

Earnings Per Common Unit (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Computation Of Basic And Diluted Earnings Per Unit	'
	approximately 16,829,000 and 17,660,000 redeemable common units for the three months ended September 30, 2013 and 2012, respectively, and approximately 16,975,000 and 17,694,000 redeemable common units for the nine months ended September 30, 2013 and 2012, respectively.
		For the three months ended September 30, 2013
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	84,497		169,236	$	0.5
	Discontinued operations attributable to Boston Properties Limited Partnership	89,643			—	0.53
	Allocation of undistributed earnings to participating securities	(651		)	—	—
	Net income attributable to Boston Properties Limited Partnership	$	173,489		169,236	$	1.03
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			285	(0.01		)
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	173,489		169,521	$	1.02
		For the three months ended September 30, 2012
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	64,684		168,461	$	0.38
	Discontinued operations attributable to Boston Properties Limited Partnership	1,550			—	0.01
	Net income attributable to Boston Properties Limited Partnership	$	66,234		168,461	$	0.39
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			1,182	—
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	66,234		169,643	$	0.39
		For the nine months ended September 30, 2013
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	628,206		168,975	$	3.72
	Discontinued operations attributable to Boston Properties Limited Partnership	112,046			—	0.66
	Allocation of undistributed earnings to participating securities	(4,183		)	—	(0.02		)
	Net income attributable to Boston Properties Limited Partnership	$	736,069		168,975	$	4.36
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			381	(0.01		)
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	736,069		169,356	$	4.35
		For the nine months ended September 30, 2012
		Income			Units	Per Unit
		(Numerator)			(Denominator)	Amount
		(in thousands, except for per unit amounts)
	Basic Earnings:
	Income from continuing operations attributable to Boston Properties Limited Partnership	$	215,296		167,517	$	1.29
	Discontinued operations attributable to Boston Properties Limited Partnership	44,041			—	0.26
	Net income attributable to Boston Properties Limited Partnership	$	259,337		167,517	$	1.55
	Effect of Dilutive Securities:
	Stock Based Compensation and Exchangeable Senior Notes	—			655	(0.01		)
	Diluted Earnings:
	Net income attributable to Boston Properties Limited Partnership	$	259,337		168,172	$	1.54

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Schedule Of Segment Information By Geographic Area And Property Type	'
	Information by geographic area and property type (dollars in thousands):
	For the three months ended September 30, 2013:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	171,228		$	198,450		$	15,636			$	53,841			$	97,925		$	537,080
	Office/Technical	5,662			—			—				5,839				3,877			15,378
	Residential	1,125			—			—				—				4,368			5,493
	Hotel	10,652			—			—				—				—			10,652
	Total	188,667			198,450			15,636				59,680				106,170			568,603
	% of Grand Totals	33.18		%	34.9		%	2.75		%		10.5		%		18.67		%	100		%
	Rental Expenses:
	Class A Office	67,798			66,322			7,033				20,006				32,170			193,329
	Office/Technical	1,763			—			—				1,287				1,064			4,114
	Residential	466			—			—				—				2,441			2,907
	Hotel	6,580			—			—				—				—			6,580
	Total	76,607			66,322			7,033				21,293				35,675			206,930
	% of Grand Totals	37.02		%	32.05		%	3.4		%		10.29		%		17.24		%	100		%
	Net operating income	$	112,060		$	132,128		$	8,603			$	38,387			$	70,495		$	361,673
	% of Grand Totals	30.98		%	36.53		%	2.38		%		10.62		%		19.49		%	100		%
	For the three months ended September 30, 2012:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	161,479		$	120,270		$	15,234			$	52,585			$	84,447		$	434,015
	Office/Technical	5,539			—			—				148				4,099			9,786
	Residential	995			—			—				—				4,501			5,496
	Hotel	9,359			—			—				—				—			9,359
	Total	177,372			120,270			15,234				52,733				93,047			458,656
	% of Grand Totals	38.67		%	26.22		%	3.32		%		11.5		%		20.29		%	100		%
	Rental Expenses:
	Class A Office	65,261			41,088			6,790				19,530				27,419			160,088
	Office/Technical	1,758			—			—				52				941			2,751
	Residential	490			—			—				—				2,364			2,854
	Hotel	6,886			—			—				—				—			6,886
	Total	74,395			41,088			6,790				19,582				30,724			172,579
	% of Grand Totals	43.11		%	23.81		%	3.93		%		11.35		%		17.8		%	100		%
	Net operating income	$	102,977		$	79,182		$	8,444			$	33,151			$	62,323		$	286,077
	% of Grand Totals	36		%	27.68		%	2.95		%		11.59		%		21.78		%	100		%
	For the nine months ended September 30, 2013:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	497,584		$	463,851		$	46,916			$	159,843			$	289,831		$	1,458,025
	Office/Technical	16,853			—			—				11,317				11,951			40,121
	Residential	3,257			—			—				—				13,298			16,555
	Hotel	30,061			—			—				—				—			30,061
	Total	547,755			463,851			46,916				171,160				315,080			1,544,762
	% of Grand Totals	35.46		%	30.02		%	3.04		%		11.08		%		20.4		%	100		%
	Rental Expenses:
	Class A Office	196,710			156,414			21,386				58,036				95,485			528,031
	Office/Technical	5,177			—			—				2,439				3,095			10,711
	Residential	1,316			—			—				—				7,154			8,470
	Hotel	20,959			—			—				—				—			20,959
	Total	224,162			156,414			21,386				60,475				105,734			568,171
	% of Grand Totals	39.45		%	27.53		%	3.77		%		10.64		%		18.61		%	100		%
	Net operating income	$	323,593		$	307,437		$	25,530			$	110,685			$	209,346		$	976,591
	% of Grand Totals	33.14		%	31.48		%	2.61		%		11.33		%		21.44		%	100		%
	For the nine months ended September 30, 2012:
		Boston			New York			Princeton				San				Washington,			Total
												Francisco				DC
	Rental Revenue:
	Class A Office	$	460,127		$	360,515		$	45,701			$	155,353			$	258,311		$	1,280,007
Office/Technical	16,882			—			—				344				12,245			29,471
Residential	2,891			—			—				—				12,122			15,013
Hotel	26,224			—			—				—				—			26,224
Total	506,124			360,515			45,701				155,697				282,678			1,350,715
% of Grand Totals	37.47		%	26.69		%	3.38		%		11.53		%		20.93		%	100		%
Rental Expenses:
Class A Office	183,601			118,531			20,889				56,496				81,613			461,130
Office/Technical	4,910			—			—				114				2,952			7,976
Residential	1,247			—			—				—				6,896			8,143
Hotel	19,601			—			—				—				—			19,601
Total	209,359			118,531			20,889				56,610				91,461			496,850
% of Grand Totals	42.14		%	23.86		%	4.2		%		11.39		%		18.41		%	100		%
Net operating income	$	296,765		$	241,984		$	24,812			$	99,087			$	191,217		$	853,865
% of Grand Totals	34.76		%	28.34		%	2.91		%		11.6		%		22.39		%	100		%
Schedule Of Reconciliation Of Net Operating Income To Net Income	'
	The following is a reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership:
		Three months ended						Nine months ended September 30,
		September 30,
		2013			2012			2013					2012
	Net Operating Income	$	361,673		$	286,077		$	976,591				$	853,865
	Add:
	Development and management services income	5,479			8,024			22,072					25,733
	Income from unconsolidated joint ventures	14,736			9,217			72,240					42,129
	Gains on consolidation of joint ventures	(1,810		)	—			385,991					—
	Interest and other income	3,879			4,001			6,646					8,029
	Gains from investments in securities	956			587			1,872					1,202
	Gains (losses) from early extinguishments of debt	(30		)	(5,494		)	122					(4,453		)
	Income from discontinued operations	1,078			1,550			5,597			—		5,596
	Gains on sales of real estate from discontinued operations	88,565			—			88,565					38,445
	Gain on forgiveness of debt from discontinued operations	—			—			20,736					—
	Less:
	General and administrative expense	24,841			21,617			94,673					72,208
	Transaction costs	766			1,140			1,744					3,252
	Depreciation and amortization expense	152,156			108,609			402,892					323,680
	Interest expense	122,173			105,030			325,746					308,168
	Impairment loss	—			—			4,401					—
	Impairment loss from discontinued operations	—			—			2,852					—
	Noncontrolling interest in property partnerships	(3,279		)	458			(924		)			1,461
	Noncontrolling interest—redeemable preferred units	3,729			874			8,796					2,440
	Net income attributable to Boston Properties Limited Partnership	$	174,140		$	66,234		$	740,252				$	259,337

Organization_Details

Organization (Details) (USD $)

9 Months Ended

60 Months Ended

3 Months Ended

3 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Mar. 26, 2018

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Aug. 07, 2013

Y

Commercial Real Estate Properties [Member]

Total Properties Under Construction [Member]

Total Office Properties [Member]

Class A Office Properties [Member]

Office Properties Under Construction [Member]

Office/Technical Properties [Member]

Hotel Properties [Member]

Retail Properties [Member]

Residential Properties [Member]

Residential Properties Under Construction [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series Two Preferred Units [Member]

Series B Preferred Units [Member]

series four preferred units [Member]

series four preferred units [Member]

sqft

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Real_Estate_Properties

Vehicles

sqft

sqft

acre

Real Estate Properties [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

General and limited partnership interest in the operating partnership (percent)

89.20%

88.60%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Restriction on redemption of OP units from date of issuance (years)

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

One OP unit is equivalent to one share of Common Stock (in shares)

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

OP unit conversion rate (in shares)

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Series B, Units Outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

80,000

0

'

80,000

'

'

Ratio of depository shares to shares of Series B Preferred Stock

'

'

'

'

'

'

'

'

'

'

'

'

'

0.01

'

'

'

'

'

Series B, Dividend Rate, Percentage

'

'

'

'

'

'

'

'

'

'

'

'

5.25%

'

'

'

'

'

'

Preferred Units Liquidation Preference

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$50

'

$50

$50

Number of series of preferred units outstanding

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

OP Units for each Preferred Unit (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.312336

'

'

'

Number of real estate properties

'

'

177

8

169

130

7

39

1

4

3

1

'

'

'

'

'

'

'

Net Rentable Area

'

'

44,600,000

2,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of vehicles in structured parking

46,221

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Area of parking structures (in square feet)

15,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Area of undeveloped land parcels owned (in acres)

512.6

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preferred Stock Dividend Payable Per Share

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0.25

'

Series Four Preferred Units Annual Dividend Payable Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2.00%

'

Basis_Of_Presentation_And_Summ3

Basis Of Presentation And Summary Of Significant Accounting Policies (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accounting Policies [Abstract]	'	'	'	'
Reclassification between general and administrative expense and real estate operating expense	$2	$1.90	$6.10	$5.80
Misstatement of real estate operating expense	'	'	'	$3.20

Basis_Of_Presentation_And_Summ4

Basis Of Presentation And Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) (USD $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
Summary Of Significant Accounting Policies [Line Items]	'		'
Mortgage notes payable	$4,468,069		$3,102,485
Mezzanine notes payable	311,340		0
Unsecured senior notes	5,835,424		4,639,528
Unsecured exchangeable senior notes	739,536		1,170,356
Impact of accounting pronouncement	-7,409		'
Carrying Amount [Member]	'		'
Summary Of Significant Accounting Policies [Line Items]	'		'
Mortgage notes payable	4,468,069		3,102,485
Mezzanine notes payable	311,340		0
Unsecured senior notes	5,835,424		4,639,528
Unsecured exchangeable senior notes	739,536	[1]	1,170,356	[1]
Total	11,354,369		8,912,369
Estimated Fair Value [Member]	'		'
Summary Of Significant Accounting Policies [Line Items]	'		'
Mortgage notes payable	4,592,273		3,256,940
Mezzanine notes payable	311,366		0
Unsecured senior notes	6,065,723		5,162,486
Unsecured exchangeable senior notes	768,019		1,278,554
Total	11,737,381		9,697,980
ASC 470-20 Adjustment [Member]	'		'
Summary Of Significant Accounting Policies [Line Items]	'		'
Impact of accounting pronouncement	$7,400		$25,500
[1]	Includes the net adjustment for the equity component allocation totaling approximately $7.4 million and $25.5 million at SeptemberB 30, 2013 and DecemberB 31, 2012, respectively.

Basis_Of_Presentation_And_Summ5

Basis Of Presentation And Summary Of Significant Accounting Policies Revision of prior period amounts for Montvale Center (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Feb. 20, 2013	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2012
					Montvale Center [Member]	Montvale Center [Member]	As Revised [Member]	As Revised [Member]	As Reported [Member]	As Reported [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'	'	'	'
Amount of debt extinguished	'	'	'	'	'	$25,000,000	'	'	'	'
Gain on forgiveness of debt from discontinued operations	0	0	20,736,000	0	20,700,000	18,400,000	'	'	'	'
Total revenue	574,082,000	466,680,000	1,566,834,000	1,376,448,000	'	'	466,680,000	1,376,448,000	470,904,000	1,389,028,000
Income from continuing operations	84,947,000	66,016,000	636,078,000	219,197,000	'	'	66,016,000	219,197,000	68,147,000	225,430,000
Discontinued Operations	1,078,000	1,550,000	5,597,000	5,596,000	'	'	1,550,000	44,041,000	0	57,690,000
Net income attributable to Boston Properties Limited Partnership	$174,140,000	$66,234,000	$740,252,000	$259,337,000	'	'	$66,234,000	$259,337,000	$66,815,000	$279,219,000
Income attributable to Boston Properties Limited Partnership per unit-basic	$1.03	$0.39	$4.36	$1.55	'	'	$0.39	$1.55	$0.40	$1.67
Income attributable to Boston Properties Limited Partnership per unit-diluted	$1.02	$0.39	$4.35	$1.54	'	'	$0.39	$1.54	$0.39	$1.66

Real_Estate_Activity_During_th2

Real Estate Activity During the Nine Months Ended September 30, 2013 (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

9 Months Ended

3 Months Ended

6 Months Ended

0 Months Ended

4 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Apr. 25, 2013

Feb. 06, 2013

Mar. 26, 2013

Feb. 26, 2013

Feb. 07, 2013

Mar. 29, 2013

Mar. 22, 2013

Mar. 31, 2013

Mar. 28, 2013

Jun. 14, 2013

Aug. 22, 2013

Sep. 30, 2013

Feb. 20, 2013

Sep. 30, 2012

Mar. 31, 2013

Mar. 28, 2013

Sep. 30, 2013

Apr. 10, 2013

31-May-13

Sep. 30, 2013

Apr. 10, 2013

Apr. 10, 2013

Sep. 30, 2013

Siz Zero One Massachusetts Avenue [Member]

535 Mission [Member]

Transbay Tower [Member]

Transbay Tower [Member]

Transbay Tower [Member]

Reston Land Parcel [Member]

Two Patriots Park [Member]

Plaza at Almaden [Member]

Plaza at Almaden [Member]

Seventeen Cambridge Center [Member]

1301 New York Avenue [Member]

1301 New York Avenue [Member]

Montvale Center [Member]

Montvale Center [Member]

303 Almaden blvd [Member]

303 Almaden blvd [Member]

Mountain View Research And Technology Parks [Member]

Mountain View Research And Technology Parks [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

Mountain View Research [Member]

Mountain View Technology [Member]

Cambridge Center Connector [Member]

sqft

floor

floor

sqft

sqft

sqft

sqft

sqft

sqft

partners

Buildings

Buildings

sqft

sqft

sqft

sqft

sqft

sqft

Real Estate Properties [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Total revenue

$574,082,000

$466,680,000

$1,566,834,000

$1,376,448,000

'

'

'

'

'

'

'

'

'

'

'

$1,511,000

'

'

'

'

$10,900,000

'

'

$95,300,000

'

'

'

Operating income

189,389,000

162,735,000

494,953,000

480,458,000

'

'

'

'

'

'

'

'

'

'

'

1,078,000

'

'

'

'

-100,000

'

'

4,100,000

'

'

'

Number of Joint Venture Partners

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

Purchase Price

'

'

522,900,000

688,073,000

'

71,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of floors real estate

'

'

'

'

'

27

60

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments to Acquire Land

'

'

'

'

'

'

192,000,000

'

'

27,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Partners Joint Venture Ownership Percentage

'

'

'

'

'

'

'

5.00%

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net Rentable Area

'

'

'

'

478,000

307,000

1,400,000

'

'

250,000

256,000

'

840,000

195,000

201,000

'

'

'

'

158,000

'

'

1,800,000

'

604,000

135,000

43,000

Aggregate purchase price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

233,100,000

'

'

'

'

'

Impairment loss from discontinued operations

0

0

2,852,000

0

'

'

'

'

'

'

'

'

'

'

'

0

'

'

2,900,000

'

'

'

'

'

'

'

'

Ownership Percentage

'

'

'

'

'

'

95.00%

95.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40.00%

'

'

'

'

Amount of debt extinguished

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25,000,000

'

'

'

'

'

'

'

'

'

Gain on forgiveness of debt from discontinued operations attributable to Boston Properties LImited Partnership

0

0

20,736,000

0

'

'

'

'

'

'

'

'

'

'

'

0

20,700,000

18,400,000

'

'

'

'

'

'

'

'

'

Contractual Sales Price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

135,000,000

'

'

'

'

40,000,000

'

'

'

'

'

'

'

Impairment loss

0

0

4,401,000

0

'

'

'

'

'

'

'

4,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Net Contractual Sales Price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

121,700,000

'

'

'

'

'

'

'

'

'

'

'

'

Number of real estate properties

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

16

7

'

Proceeds from sales of real estate

'

'

160,815,000

61,963,000

'

'

'

'

'

'

'

'

'

'

121,500,000

'

'

'

'

'

'

'

'

'

'

'

'

Gains on sale of real estate from discontinued operations

$88,565,000

$0

$88,565,000

$38,445,000

'

'

'

'

'

'

'

'

'

'

$88,600,000

$88,565,000

'

'

'

'

'

'

'

'

'

'

'

Real_Estate_Activity_During_th3

Real Estate Activity During the Nine Months Ended September 30, 2013 Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition (Details) (USD $)	9 Months Ended			0 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Apr. 10, 2013	31-May-13		31-May-13	31-May-13
				Mountain View Research And Technology Parks [Member]	767 Fifth Avenue (The GM Building) [Member]		767 Fifth Avenue (The GM Building) [Member]	Consolidation, Eliminations [Member]
								767 Fifth Avenue (The GM Building) [Member]
Business Acquisition [Line Items]	'	'	'	'	'		'	'
Land	'	'	'	$126,521	$1,796,252		'	'
Building and improvements	'	'	'	82,451	1,447,446		'	'
Tenant improvements	'	'	'	7,326	85,208		'	'
In-place lease Intangibles	'	'	'	23,279	357,781		'	'
Above market rents	'	'	'	843	101,897		'	'
Below market rents	'	'	'	7,336	239,641		'	'
Above market assumed debt adjustments	'	'	'	'	192,943		'	'
Net assets acquired	'	'	'	233,084	'		'	'
Real estate and related intangibles recorded upon consolidation	3,356,000	0	'	'	3,356,000		'	'
Mortgage notes payable	4,468,069	'	3,102,485	'	1,300,000		'	'
Mezzanine notes payable	311,340	'	0	'	306,000		'	'
Related party notes payable	180,000	'	0	'	450,000	[1]	'	270,000
Debt recorded upon consolidation	2,056,000	0	'	'	-2,056,000		'	'
Cash and cash equivalents	79,468	0	'	'	79,468		'	'
Cash held in escrows	'	'	'	'	2,403		'	'
Tenant and other receivables	'	'	'	'	7,104		'	'
Prepaid expense and other assets	'	'	'	'	4,269		'	'
Accounts payable and accrued expenses	'	'	'	'	2,418		'	'
Accrued interest payable	181,310	'	72,461	'	182,369	[2]	'	105,500
Other liabilities	'	'	'	'	6,304		'	'
Working capital recorded upon consolidation	97,847	0	'	'	-97,847		'	'
Noncontrolling Interet	'	'	'	'	520,000		'	'
Noncontrolling Interet working capital	'	'	'	'	-39,139		'	'
Noncontrolling interest recorded upon consolidation	-480,861	0	'	'	-480,861		'	'
Net Assets Recorded Upon Consolidation	'	'	'	'	'		$721,292	'
[1]	The Company's partner loans totaling $270.0 million eliminates in consolidation.
[2]	The Company's share of the accrued interest payable on the partner loans totaling approximately $105.5 million eliminates in consolidation.

Real_Estate_Activity_During_th4

Real Estate Activity During the Nine Months Ended September 30, 2013 (Summary Of The Discontinued Operations Related to Montvale Center, 303 Almaden Blvd, 1301 New York Avenue and Beford Business Park) (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended			9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Aug. 22, 2013	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
					1301 New York Avenue [Member]	1301 New York Avenue [Member]	303 Almaden blvd [Member]	Montvale Center, 303 Almaden Blvd and Bedford Business Park [Member]	Montvale Center, 303 Almaden Blvd and Bedford Business Park [Member]	Montvale Center, 303 Almaden Blvd, 1301 New York Avenue and Bedford Business Park [Member] [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'	'	'	'	'	'	'	'
Total revenue	$574,082	$466,680	$1,566,834	$1,376,448	'	$1,511	'	$4,882	$10,469	$17,940
Expenses	'	'	'	'	'	'	'	'	'	'
Operating	'	'	'	'	'	433	'	1,781	3,447	6,725
Depreciation and amortization	152,156	108,609	402,892	323,680	'	0	'	901	1,065	3,675
Total expenses	384,693	303,945	1,071,881	895,990	'	433	'	2,682	4,512	10,400
Operating income	189,389	162,735	494,953	480,458	'	1,078	'	2,200	5,957	7,540
Other expense	'	'	'	'	'	'	'	'	'	'
Interest expense	-122,173	-105,030	-325,746	-308,168	'	0	'	-650	-360	-1,944
Income from discontinued operations	89,643	1,550	112,046	44,041	'	1,078	'	1,550	5,597	5,596
Gains on sale of real estate from discontinued operations	88,565	0	88,565	38,445	88,600	88,565	'	0	88,565	38,445
Gain on forgiveness of debt from discontinued operations attributable to Boston Properties LImited Partnership	0	0	20,736	0	'	0	'	0	'	0
Impairment loss from discontinued operations attributable to Boston Properties Limited Partnership	$0	$0	($2,852)	$0	'	$0	($2,900)	$0	'	$0

Real_Estate_Activity_During_th5

Real Estate Activity During the Nine Months Ended September 30, 2013 Business Acquistion pro forma (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended	3 Months Ended	9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	31-May-13	Sep. 30, 2013	Sep. 30, 2012
					Mountain View Research And Technology Parks [Member]	767 Fifth Avenue (The GM Building) [Member]	767 Fifth Avenue (The GM Building) [Member]	767 Fifth Avenue (The GM Building) [Member]
Business Acquisition [Line Items]	'	'	'	'	'	'	'	'
Gain on consolidation of joint ventures	($1,810)	$0	$385,991	$0	$26,500	$359,500	($3,900)	$359,500
Total Revenue	'	'	1,688,393	1,602,949	'	'	'	'
Income from continuing operations	'	'	234,784	573,170	'	'	'	'
Net income attributable to Boston Properties Limited Partnership	'	'	$351,549	$633,626	'	'	'	'
Basic earnings per share, Net income attributable to Boston Properties Limited Partnership (dollars per share)	'	'	$2.08	$3.76	'	'	'	'
Diluted earnings per share, Net income attributable to Boston Properties Limited Partnership (dollars per share	'	'	$2.07	$3.75	'	'	'	'

Investments_in_Unconsolidated_2

Investments in Unconsolidated Joint Ventures Investment in Unconsolidated Joint Ventures (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

30-May-13

Apr. 10, 2013

Sep. 30, 2013

Apr. 10, 2013

Apr. 10, 2013

Apr. 10, 2013

Feb. 28, 2013

31-May-13

Sep. 30, 2013

Oct. 29, 2013

Apr. 04, 2013

Sep. 26, 2013

Jun. 05, 2013

Jul. 19, 2013

31-May-13

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2012

Apr. 10, 2013

31-May-13

Apr. 10, 2013

Apr. 10, 2013

31-May-13

Jun. 05, 2013

Jun. 05, 2013

Apr. 10, 2013

30-May-13

Jul. 19, 2013

31-May-13

Jun. 05, 2013

Apr. 10, 2013

Sep. 30, 2013

125 West55th Street [Member]

125 West55th Street [Member]

Boston Properties Office Value-Added Fund, L.P. [Member]

Mountain View Research And Technology Parks [Member]

Mountain View Technology [Member]

Mountain View Research [Member]

Annapolis Junction Building Six [Member]

500 North Capitol [Member]

500 North Capitol [Member]

Annapolis Junction Building Seven [Member]

Annapolis Junction Building Seven [Member]

Annapolis Junction Building Seven [Member]

540 Madison Avenue [Member]

8th Avenue and 46th Street [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

Mountain View Research And Technology Parks [Member]

Mountain View Research And Technology Parks [Member]

Construction Loans [Member]

Mountain View Technology [Member]

Mountain View Research [Member]

First Mortgage [Member]

First Mortgage [Member]

Prior to refinance first mortgage loan [Member]

Company [Member]

Company [Member]

Company [Member]

Company [Member]

Company [Member]

Mountain View Research And Technology Parks [Member]

Value Added Fund [Member]

sqft

sqft

sqft

sqft

Y

sqft

partners

500 North Capitol [Member]

500 North Capitol [Member]

540 Madison Avenue [Member]

540 Madison Avenue [Member]

125 West55th Street [Member]

8th Avenue and 46th Street [Member]

Construction Loans [Member]

Prior to refinance first mortgage loan [Member]

sqft

500 North Capitol [Member]

540 Madison Avenue [Member]

Schedule of Equity Method Investments [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Description of Variable Rate Basis

'

'

'

'

'

'

'

'

'LIBOR plus 2.50%

'LIBOR plus 2.00%

'

'LIBOR plus 1.65%

'

'LIBOR plus 1.65%

'

'

'LIBOR plus 1.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity Method Investment, Ownership Percentage

'

'

'

'

'

60.00%

39.50%

[1]

'

'

'

50.00%

30.00%

30.00%

50.00%

50.00%

50.00%

60.00%

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

39.50%

'

Net Rentable Area

'

'

'

'

'

588,000

'

'

'

'

119,000

'

231,000

119,000

'

125,000

'

'

1,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Construction Loan Facility Borrowing Capacity

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$22,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Basis Spread on Variable Rate

'

'

'

'

'

'

'

'

2.50%

2.00%

'

'

'

1.65%

1.65%

'

'

'

'

'

'

'

'

1.65%

'

'

'

1.50%

'

'

'

'

'

'

'

'

Maturity date

'

'

'

'

10-Mar-20

'

'

'

22-Nov-14

31-May-14

'

'

'

17-Nov-14

4-Apr-16

'

'

'

'

'

'

'

'

14-Oct-14

'

'

6-Jun-23

5-Jun-18

11-Jul-13

'

'

'

'

'

'

'

Proceeds from Sale of Equity Method Investments

'

'

223,067,000

3,057,000

253,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

152,200,000

'

'

'

'

'

Losses from Early Extinguishment of Debt

-30,000

-5,494,000

122,000

-4,453,000

'

'

'

-400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,000,000

'

'

'

'

-300,000

-200,000

'

'

-300,000

-200,000

'

'

Number of extensions

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Extension Option (in years)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate purchase price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

233,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Repayments of Secured Debt

'

'

96,750,000

248,304,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

90,600,000

20,000,000

90,000,000

'

'

118,000,000

'

'

'

'

'

'

'

Repayments of Notes Payable

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,700,000

8,600,000

'

'

'

'

'

'

'

'

'

'

Ownerhip upon acquistion

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

Gains on Consolidation of Joint Ventures

1,810,000

0

-385,991,000

0

'

'

'

-26,500,000

'

'

'

'

'

'

'

'

'

'

-359,500,000

3,900,000

-359,500,000

-26,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

-2,100,000

Contractual Sales Price

'

'

'

'

'

470,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Carrying Value of Debt Assumed in Sale

'

'

'

'

198,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Gain on sale of real estate

'

'

'

'

43,200,000

'

'

'

'

'

'

'

'

'

'

'

'

12,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

11,300,000

'

'

'

'

Number of Joint Venture Partners

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Issuance of Secured Debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

105,000,000

120,000,000

'

'

'

'

'

'

'

'

Coupon/Stated Rate (percent)

'

'

'

'

6.09%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.15%

'

5.20%

'

'

'

'

'

'

'

Imputed Sales Price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

45,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Equity Method Investment, Net Sales Proceeds

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$21,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

[1]

The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of SeptemberB 30, 2013, the investment is comprised of undistributed cash.

Investments_in_Unconsolidated_3

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details)	9 Months Ended
	Sep. 30, 2013
Square 407 Limited Partnership [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'MarketB SquareB North
Equity Method Investment, Ownership Percentage	50.00%
The Metropolitan Square Associates LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'Metropolitan Square
Equity Method Investment, Ownership Percentage	51.00%
BP/CRF 901 New York Avenue LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'901B NewB YorkB Avenue	[1]
Equity Method Investment, Ownership Percentage	25.00%	[1]
WP Project Developer LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'Wisconsin Place Land and Infrastructure	[2]
Equity Method Investment, Ownership Percentage	33.30%	[2]
RBP Joint Venture LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'N/A	[3]
Equity Method Investment, Ownership Percentage	50.00%	[3]
Boston Properties Office Value-Added Fund, L.P. [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'N/A	[4]
Equity Method Investment, Ownership Percentage	39.50%	[4]
Annapolis Junction NFM, LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'Annapolis Junction	[5]
Equity Method Investment, Ownership Percentage	50.00%	[5]
Number of real estate properties	2
Number of buildings under construction	1
Parcels of undeveloped land	2
2 GCT Venture LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'N/A	[6]
Equity Method Investment, Ownership Percentage	60.00%	[6]
540 Madison Venture LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'540 Madison Avenue
Equity Method Investment, Ownership Percentage	60.00%
125 West 55th Street Venture LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'N/A	[7]
Equity Method Investment, Ownership Percentage	60.00%	[7]
500 North Capitol LLC [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Properties	'500 North Capitol Street, NW
Equity Method Investment, Ownership Percentage	30.00%
Entity Owning Land And Infrastructure Of Project [Member]	'
Schedule of Equity Method Investments [Line Items]	'
Equity Method Investment, Ownership Percentage	33.30%
[1]	The Companybs economic ownership can increase based on the achievement of certain return thresholds.
[2]	The Companybs wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land and infrastructure of the project.
[3]	Eighth Avenue and 46th Street was sold on JulyB 19, 2013.
[4]	The Company acquired Mountain View Research Park and Mountain View Technology Park from the Value-Added Fund on April 10, 2013 (See Note 3). As of SeptemberB 30, 2013, the investment is comprised of undistributed cash.
[5]	Comprised of two buildings, one building under construction and two undeveloped land parcels.
[6]	Two Grand Central Tower was sold on OctoberB 25, 2011. As of SeptemberB 30, 2013, the investment is comprised of undistributed cash.
[7]	125 West 55th Street was sold on MayB 30, 2013. As of SeptemberB 30, 2013, the investment is comprised of undistributed cash.

Investments_in_Unconsolidated_4

Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) (USD $)	Sep. 30, 2013		Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS	'		'
Real estate and development in process, net	$15,458,406		$11,577,979
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY	'		'
Mortgage notes payable	4,468,069		3,102,485
Other liabilities	567,464		324,613
Total liabilities and capital	19,151,515		15,081,132
Carrying value of the Company's investments in unconsolidated joint ventures	129,038		659,916
Unconsolidated Joint Ventures [Member]	'		'
ASSETS	'		'
Real estate and development in process, net	927,890		4,494,971
Other assets	158,105		673,716
Total assets	1,085,995		5,168,687
LIABILITIES AND MEMBERS'/PARTNERS' EQUITY	'		'
Mortgage notes payable	748,489		3,039,922
Other liabilities	21,183		792,888
Members'/Partners' equity	316,323		1,335,877
Total liabilities and capital	1,085,995		5,168,687
Company's share of equity	157,875		787,941
Basis differentials	-28,837	[1]	-128,025	[1]
Carrying value of the Company's investments in unconsolidated joint ventures	$129,038		$659,916
[1]	unt represents the aggregate difference between the Companybs historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from impairment of investments and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level.

Investments_in_Unconsolidated_5

Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Schedule of Equity Method Investments [Line Items]	'		'		'		'
Total revenue	$574,082,000		$466,680,000		$1,566,834,000		$1,376,448,000
Expenses	'		'		'		'
Depreciation and amortization	152,156,000		108,609,000		402,892,000		323,680,000
Total expenses	384,693,000		303,945,000		1,071,881,000		895,990,000
Operating income	189,389,000		162,735,000		494,953,000		480,458,000
Other expense	'		'		'		'
Interest expense	122,173,000		105,030,000		325,746,000		308,168,000
Losses from Early Extinguishment of Debt	-30,000		-5,494,000		122,000		-4,453,000
Income from continuing operations	84,947,000		66,016,000		636,078,000		219,197,000
Net income	174,590,000		67,566,000		748,124,000		263,238,000
Income from unconsolidated joint ventures	14,736,000		9,217,000		72,240,000		42,129,000
Gains on Consolidation of Joint Ventures	1,810,000		0		-385,991,000		0
Unconsolidated Joint Ventures [Member]	'		'		'		'
Schedule of Equity Method Investments [Line Items]	'		'		'		'
Total revenue	37,983,000	[1]	135,998,000	[1]	273,464,000	[1]	431,133,000	[1]
Expenses	'		'		'		'
Operating	14,963,000		42,298,000		89,826,000		120,451,000
Depreciation and amortization	9,784,000		39,291,000		76,202,000		123,869,000
Total expenses	24,747,000		81,589,000		166,028,000		244,320,000
Operating income	13,236,000		54,409,000		107,436,000		186,813,000
Other expense	'		'		'		'
Interest expense	8,148,000		56,521,000		104,436,000		167,792,000
Losses from Early Extinguishment of Debt	0		0		-1,677,000		0
Income from continuing operations	5,088,000		-2,112,000		1,323,000		19,021,000
Gain on sale of real estate	12,441,000		990,000		14,207,000		990,000
Net income	17,529,000		-1,122,000		15,530,000		20,011,000
Company's share of net income (loss)	3,149,000		-1,420,000		1,974,000		10,591,000
Gain on sale of real estate	11,174,000		0		54,501,000		0
Basis differential	413,000		384,000		-1,213,000		1,282,000
Elimination of inter-entity interest on partner loan	0		10,253,000		16,978,000		30,256,000
Income from unconsolidated joint ventures	14,736,000		9,217,000		72,240,000		42,129,000
Gains on Consolidation of Joint Ventures	1,810,000		0		-385,991,000		0
Straight Line Rent Adjustments	-600,000		-2,200,000		7,600,000		9,300,000
Below market rent adjustments, net	-100,000		22,100,000		33,900,000		70,600,000
Termination income	'		'		'		19,600,000
Company Share Of Termination Income	'		'		'		$11,800,000
[1]	udes straight-line rent adjustments of $0.6 million and $2.2 million for the three months ended September 30, 2013 and 2012, respectively, and $7.6 million and $9.3 million for the nine months ended September 30, 2013 and 2012, respectively. Includes net below-market rent adjustments of $(0.1) million and $22.1 million for the three months ended September 30, 2013 and 2012, respectively, and $33.9 million and $70.6 million for the nine months ended September 30, 2013 and 2012, respectively. Total revenue for the nine months ended September 30, 2012 includes termination income totaling approximately $19.6 million (of which the Company's share is approximately $11.8 million) related to a lease termination with a tenant at 767 Fifth Avenue (the General Motors Building).On Feb

Mortgage_Notes_Payable_Narrati

Mortgage Notes Payable (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

0 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Feb. 20, 2013

Sep. 30, 2012

Feb. 05, 2013

Sep. 30, 2013

31-May-13

Sep. 30, 2013

31-May-13

31-May-13

31-May-13

31-May-13

Montvale Center [Member]

Montvale Center [Member]

Kingstowne One [Member]

140 Kendrick [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

First Mortgage [Member]

Subordinated Debt [Member]

Consolidation, Eliminations [Member]

Company [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

767 Fifth Avenue (The GM Building) [Member]

Mortgage Notes Payable [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Repayments of Secured Debt

'

'

$96,750,000

$248,304,000

'

'

'

$17,000,000

$47,600,000

'

'

'

'

'

'

Coupon/Stated Rate (percent)

'

'

'

'

'

'

'

5.96%

7.51%

11.00%

'

5.95%

6.02%

'

'

Maturity date

'

'

'

'

'

'

'

5-May-13

1-Jul-13

9-Jun-17

'

7-Oct-17

7-Oct-17

'

'

Penalty For Early Repayment Of Debt

'

'

'

'

'

'

'

0

0

'

'

'

'

'

'

Amount of debt extinguished

'

'

'

'

'

'

25,000,000

'

'

'

'

'

'

'

'

Gain on forgiveness of debt from discontinued operations

0

0

20,736,000

0

'

20,700,000

18,400,000

'

'

'

'

'

'

'

'

Gains from early extinguishments of debt

-30,000

-5,494,000

122,000

-4,453,000

'

'

'

'

300,000

'

'

'

'

'

'

Indebtedness assumed

'

'

'

'

'

'

'

'

'

'

'

1,300,000,000

306,000,000

'

'

MortgageLoans Accounted For At Fair Value Upon Consolidation

'

'

'

'

'

'

'

'

'

1,500,000,000

'

'

311,700,000

'

'

Interest Rate Used To Account For Mortgage Loan At Fai rValue Upon Consolidation

'

'

'

'

'

'

'

'

'

'

'

2.44%

5.53%

'

'

Related party notes payable

180,000,000

'

180,000,000

'

0

'

'

'

'

450,000,000

'

'

'

270,000,000

180,000,000

Accrued interest payable

$181,310,000

'

$181,310,000

'

$72,461,000

'

'

'

'

'

$175,800,000

'

'

'

'

Unsecured_Senior_Notes_Unsecur1

Unsecured Senior Notes Unsecured Senior Notes (Narrative) (details) (USD $)	9 Months Ended		0 Months Ended	9 Months Ended		0 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Apr. 11, 2013	Sep. 30, 2013		Jun. 27, 2013	Sep. 30, 2013		Sep. 30, 2013
			3.279%Unsecured Senior Notes [Member]	3.279%Unsecured Senior Notes [Member]		3.916% Unsecured Senior Notes [Member]	3.916% Unsecured Senior Notes [Member]		Senior Notes [Member]
Debt Instrument [Line Items]	'	'	'	'		'	'		'
Proceeds from unsecured senior notes	$1,194,753,000	$997,790,000	$492,500,000	'		$691,900,000	'		'
Maximum Leverage Ratio	'	'	'	'		'	'		60.00%
Maximum Secured Debt Leverage Ratio	55.00%	'	'	'		'	'		50.00%
Minimum Interest Coverage Ratio	'	'	'	'		'	'		1.5
Minimum Unencumbered Asset Value Percentage Of Unsecured Debt	'	'	'	'		'	'		150.00%
Debt Instrument, Face Amount	'	'	$500,000,000	'		$700,000,000	'		'
Coupon/Stated Rate (percent)	'	'	3.13%	3.13%		3.80%	3.80%		'
Senior Notes Pricing	'	'	99.38%	'		99.69%	'		'
Effective Percentage	'	'	3.28%	3.28%	[1]	3.92%	3.92%	[1]	'
Maturity date	'	'	1-Sep-23	1-Sep-23	[2]	1-Feb-24	1-Feb-24	[2]	'
[1]	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.
[2]	No principal amounts are due prior to maturity.

Unsecured_Senior_Notes_Schedul

Unsecured Senior Notes Schedule of Unsecured Senior Notes (Details) (USD $)

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Apr. 11, 2013

Sep. 30, 2013

Jun. 27, 2013

Sep. 30, 2013

Sep. 30, 2013

In Thousands, unless otherwise specified

5.693% unsecured senior notes [Member]

5.194% Unsecured Senior Notes [Member]

5.967% unsecured Senior Notes [Member]

5.708%Unsecured Senior Notes [Member]

4.289% Unsecured Senior Notes [Member]

3.853% Unsecured Senior Notes [Member]

3.954% Unsecured Senior Notes [Member]

3.279%Unsecured Senior Notes [Member]

3.279%Unsecured Senior Notes [Member]

3.916% Unsecured Senior Notes [Member]

3.916% Unsecured Senior Notes [Member]

Senior Notes [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Coupon/Stated Rate (percent)

'

'

5.63%

5.00%

5.88%

5.63%

4.13%

3.70%

3.85%

3.13%

3.13%

3.80%

3.80%

'

Effective Percentage

'

'

5.69%

[1]

5.19%

[1]

5.97%

[1]

5.71%

[1]

4.29%

[1]

3.85%

[1]

3.95%

[1]

3.28%

3.28%

[1]

3.92%

3.92%

[1]

'

Principal Amount

'

'

$300,000

$250,000

$700,000

$700,000

$850,000

$850,000

$1,000,000

'

$500,000

'

$700,000

$5,850,000

Maturity date

'

'

15-Apr-15

[2]

1-Jun-15

[2]

15-Oct-19

[2]

15-Nov-20

[2]

15-May-21

[2]

15-Nov-18

[2]

1-Feb-23

[2]

1-Sep-23

1-Sep-23

[2]

1-Feb-24

1-Feb-24

[2]

'

Unsecured senior notes, discount

14,576

10,472

'

'

'

'

'

'

'

'

'

'

'

-14,576

Unsecured senior notes

$5,835,424

$4,639,528

'

'

'

'

'

'

'

'

'

'

'

$5,835,424

[1]

Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs.

[2]

No principal amounts are due prior to maturity.

Unsecured_Exchangeable_Senior_2

Unsecured Exchangeable Senior Notes Schedule of Unsecured Exchangeable Senior Notes (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Aug. 15, 2008	Sep. 30, 2013
				3.625% exchangeable senior notes [Member]
Debt Instrument [Line Items]	'	'	'	'
Share Price	$134.14	'	$97.98	'
Net Cost Of Capped Call Transaction	$44,400,000	'	'	'
Increment Of The Notes For Purposes Of Disclosing Initial Exchange Rate	1,000	'	'	'
Debt Instrument, Convertible, Conversion Price	$117.58	'	'	'
Initial Exchange Rate	8.5051	'	'	'
Adjusted Exchange Price Due To Capped Call	$137.17	'	'	'
Coupon/Stated Rate (percent)	'	'	'	3.63%
Effective Percentage	'	'	'	4.04%	[1]
Exchange Rate	'	'	'	8.5051	[2]
Principal Amount	'	'	'	747,500,000
Maturity date	'	'	'	15-Feb-14
Unsecured exchangeable senior notes, discount	555,000	1,653,000	'	'
Adjustment for the equity component allocation, net of accumulated amortization	-7,409,000	'	'	'
Unsecured exchangeable senior notes	$739,536,000	$1,170,356,000	'	'
Premium Over Closing Price Due To Capped Call	40.00%	'	'	'
[1]	Yield on issuance date including the effects of discounts on the notes and the amortization of financing costs but excluding the effects of the adjustment for the equity component allocation.
[2]	The initial exchange rate is 8.5051 shares per $1,000 principal amount of the notes (or an initial exchange price of approximately $117.58 per share of Boston Properties, Inc.bs common stock). In addition, the Company entered into capped call transactions with affiliates of certain of the initial purchasers, which are intended to reduce the potential dilution upon future exchange of the notes. The capped call transactions were intended to increase the effective exchange price to the Company of the notes from $117.58 to approximately $137.17 per share (subject to adjustment), representing an overall effective premium of approximately 40% over the closing price on AugustB 13, 2008 of $97.98 per share of Boston Properties, Inc.bs common stock. The net cost of the capped call transactions was approximately $44.4 million. As of SeptemberB 30, 2013, the effective exchange price was $134.14 per share.

Unsecured_Exchangeable_Senior_3

Unsecured Exchangeable Senior Notes Unsecured exchangeable Senior Notes (Narrative) (details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	18-May-13	18-May-13	18-May-13
					3.75%T Exchangeable Senior Notes [Member]	3.75%T Exchangeable Senior Notes [Member]	3.75%T Exchangeable Senior Notes [Member]
						Redeemed amount [Member]	Submitted for Exchange [Member]
Debt Instrument [Line Items]	'	'	'	'	'	'	'
Coupon/Stated Rate (percent)	'	'	'	'	3.75%	'	'
Debt Instrument, Redemption Date	'	'	'	'	18-May-13	'	'
Debt Instrument Redemption Price Principal Percentage	'	'	'	'	100.00%	'	'
Redemption of unsecured senior notes	'	'	$0	$225,000,000	'	$990,000	$449,010,000
Common Stock, Shares, Issued	'	'	'	'	419,116	'	'
Losses from Early Extinguishment of Debt	($30,000)	($5,494,000)	$122,000	($4,453,000)	($100,000)	'	'

Unsecured_Line_of_Credit_Detai

Unsecured Line of Credit (Details) (USD $)

Sep. 30, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Jul. 26, 2013

Y

Prior to Amendment [Member]

After Amendment [Member]

Alternative Base Interest Rate Calculation [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Rate Based on Current Credit Rating [Member]

Rate Based on Current Credit Rating [Member]

Rate Based on Current Credit Rating [Member]

M

After Amendment [Member]

Interest Rate Based on LIBOR or CDOR [Member]

Alternative Base Interest Rate Calculation [Member]

Interest Rate Based on LIBOR or CDOR [Member]

Alternative Base Interest Rate Calculation [Member]

Interest Rate Based on LIBOR or CDOR [Member]

Alternative Base Interest Rate Calculation [Member]

Current Rates Based on Credit Ratings [Member]

Line of Credit Facility [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Leverage Ratio Reduction Limit

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount added to LIBOR to Calculate Interest Rate

'

'

'

1.00%

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Current Borrowing Capacity

'

$750,000,000

$1,000,000,000

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Expiration Date

'

24-Jun-14

26-Jul-18

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Maximum Borrowing Capacity

'

'

'

'

'

1,500,000,000

'

'

'

'

'

'

'

'

Margin added to Calculated Interest Rate

'

'

'

'

'

'

1.70%

0.70%

'

0.93%

0.00%

1.00%

0.00%

'

Line of Credit Facility, Unused Capacity, Commitment Fee Percentage

'

'

'

'

0.35%

'

'

'

0.13%

'

'

'

'

0.15%

Amount added to Federal Funds Rate to Calculate Interest Rate

'

'

'

0.50%

'

'

'

'

'

'

'

'

'

'

LIBOR Period Used to Calculate Interest Rate (in months)

'

'

'

1

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Amount Outstanding

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

Leverage Ratio Maximum

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Leverage Ratio Maximum Increasing Limit

65.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Leverage Ratio Reduction Period, Years

1

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum Secured Debt Leverage Ratio

55.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Fixed Charge Coverage Ratio Minimum.

1.4

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum Unsecured Debt Leverage Ratio

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Unsecured Debt Leverage Ratio Maximum Increasing Limit

65.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Unsecured Debt Leverage Ratio Reduction Limit

60.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

Unsecured Debt Leverage Ratio Reduction Period, Years

1

'

'

'

'

'

'

'

'

'

'

'

'

'

Unsecured Debt Interest Coverage Ratio Minimum.

1.75

'

'

'

'

'

'

'

'

'

'

'

'

'

Commitments_And_Contingencies_

Commitments And Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies [Line Items]	'
Letter of credit and performance obligations	$13,900,000
Property insurance program per occurrence limits	1,000,000,000
Per occurrence limit for NBCR Coverage	1,000,000,000
Value of program trigger	100,000,000
Coinsurance of program trigger (percent)	15.00%
Deductible in insurance as a percentage of the value of the affected property, San Francisco (percent)	5.00%
Per occurrence limit of the earthquake insurance which covers San Francisco region	120,000,000
Annual aggregate limit of the earthquake insurance which covers San Francisco region	120,000,000
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco	20,000,000
Earthquake Coverage Included in Builders Risk Policy for 680 Folsom	20,000,000
Earthquake Coverage Included In Builders Risk Policy For 535 Mission	15,000,000
Operating partnership guarantee to cover liabilities of IXP	20,000,000
767 Venture, LLC [Member]	'
Commitments And Contingencies [Line Items]	'
Maximum funding obligation	11,400,000
Property insurance program per occurrence limits	1,625,000,000
Coverage for acts of Terrorism certified under TRIA in excess of amount provided by NYIXP, LLC, as a direct insurer	1,375,000,000
Coverage for acts of terrorism certified under TRIA in excess	250,000,000
John Hancock Tower [Member]	'
Commitments And Contingencies [Line Items]	'
Guarantee Obligation Related To Tenant Re-Leasing Costs	15,900,000
601 Lexington Avenue [Member]	'
Commitments And Contingencies [Line Items]	'
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP	$250,000,000

Noncontrolling_Interests_Narra

Noncontrolling Interests (Narrative) (Details)	Sep. 30, 2013
Noncontrolling Interests [Member]	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'
Operating Partnership (OP) Units (in shares)	15,738,523
Long-Term Incentive Plan (LTIP) Units (in shares)	1,460,200
Series Two Preferred Units (in shares)	995,997
Convertible Operating Partnership (OP) Units (in shares)	1,307,083
Series Four Preferred Units (in shares)	360,126
OPP Units Two Thousand And Eleven [Member]	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'
Outperformance awards in LTIP Units (in shares)	396,500
OPP Units Two Thousand And Twelve [Member]	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'
Outperformance awards in LTIP Units (in shares)	396,150
MYLTIP [Member]	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'
2013 MYLTIP	316,325

Noncontrolling_Interests_Redee

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) (USD $)

Sep. 30, 2013

Oct. 21, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Aug. 15, 2013

15-May-13

14-May-13

Feb. 15, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Sep. 30, 2013

Aug. 07, 2013

Sep. 30, 2013

Aug. 15, 2013

29-May-13

15-May-13

Feb. 15, 2013

Oct. 21, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

In Millions, except Share data, unless otherwise specified

Noncontrolling Interests [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

Series Two Preferred Units [Member]

series four preferred units [Member]

series four preferred units [Member]

series four preferred units [Member]

series four preferred units [Member]

series four preferred units [Member]

series four preferred units [Member]

series four preferred units [Member]

OP Units [Member]

OP Units [Member]

OP Units [Member]

Redemption Year Two Thousand Fourteen [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

D

Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Conversion of Stock, Shares Converted

'

329,881

'

117,407

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

432,914

153,605

'

'

Maximum Redeemable On Redemption Dates Preferred Units

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,007,662

Series Two Preferred Units (in shares)

995,997

'

'

'

995,997

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Liquidation preference percentage

'

'

'

'

6.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Operating Units liquidation preference (in dollars per share)

'

'

'

'

$38.10

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

OP Units for each Preferred Unit (in shares)

'

'

1.312336

'

1.312336

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Series Two Preferred Units redemption price per unit (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$50

Dates Series Two Preferred holders can require Operating Partnership to redeem their units for cash

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

12-May-14

Distributions to Series Two Preferred Units (in dollars per share)

'

'

'

'

'

$0.85

$0.85

'

$0.85

'

'

'

'

'

'

'

$0.25

'

$0.25

$0.25

'

'

'

'

Maximum portion that may be required for redemption of total

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'0.1666666667

Value of Series Two Preferred Units assuming conversion

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$139.70

'

Closing price of common stock (in dollars per share)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$106.90

'

Series Four Preferred Units (in shares)

360,126

'

'

'

'

'

'

'

'

'

'

'

'

'

'

360,126

'

'

'

'

'

'

'

'

Series Four Preferred Units Annual Dividend Payable Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

2.00%

'

2.00%

'

'

'

'

'

'

'

'

Preferred Units Liquidation Preference

'

'

$50

'

$50

'

'

'

'

'

'

'

'

$50

$50

$50

'

'

'

'

'

'

'

'

First opportunity to redeem Series Four Preferred Units (in days)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

30

'

'

'

'

'

'

Series Four Preferred Units Redeemed

'

'

'

'

'

'

'

'

'

'

'

'

'

'

861,400

'

'

'

'

'

'

'

'

'

Number Of Holders Exercises

'

'

'

'

'

'

'

0

'

0

0

0

0

'

'

'

'

'

'

'

'

'

'

'

Noncontrolling_Interests_Commo

Noncontrolling Interests (Common Units) (Narrative) (Details) (USD $)	0 Months Ended			9 Months Ended
In Billions, except Share data, unless otherwise specified	Jul. 31, 2013	Apr. 30, 2013	Jan. 29, 2013	Sep. 30, 2013	Sep. 18, 2013
OP Units [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
OP Units for redemption (in shares)	'	'	'	336,935	'
Redemption of OP units issued on conversion of LTIP Units (in shares)	'	'	'	19,589	'
Outperformance Awards LTIP Units distribution as percentage of OP Unit distribution prior to measurement date	'	'	'	10.00%	'
Distributions made to OP and LTIP units per unit (in dollars per share)	$0.65	$0.65	$0.65	'	'
Distribution paid to outperformance awards, OPP Units (in dollars per share)	$0.07	$0.07	$0.07	'	'
Distribution declared to OP and LTIP units by Boston Properties, Inc. (in dollars per share)	'	'	'	'	$0.65
Distribution declared to outperformance awards OPP Units by Boston Properties, Inc. (in dollars per share)	'	'	'	'	$0.07
Common units of operating partnership if converted value	'	'	'	$1.80	'
OPP Units Two Thousand And Eleven [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Outperformance awards in LTIP Units (in shares)	'	'	'	396,500	'
OPP Units Two Thousand And Twelve [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Outperformance awards in LTIP Units (in shares)	'	'	'	396,150	'
Quarter 4 2012 [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend shareholder of record date	'	'	'	31-Dec-12	'
Dividend payable date	'	'	'	29-Jan-13	'
Quarter 4 2012 [Member] | OP Units [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend payable date	'	'	'	29-Jan-13	'
Holders of record date	'	'	'	31-Dec-12	'
Quarter 1 2013 [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend shareholder of record date	'	'	'	29-Mar-13	'
Dividend payable date	'	'	'	30-Apr-13	'
Quarter 1 2013 [Member] | OP Units [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend payable date	'	'	'	30-Apr-13	'
Holders of record date	'	'	'	29-Mar-13	'
Quarter 2 2013 [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend shareholder of record date	'	'	'	28-Jun-13	'
Dividend payable date	'	'	'	31-Jul-13	'
Quarter 2 2013 [Member] | OP Units [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend payable date	'	'	'	31-Jul-13	'
Holders of record date	'	'	'	28-Jun-13	'
Quarter 3 2013 [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividend shareholder of record date	'	'	'	30-Sep-13	'
Dividends declared date	'	'	'	18-Sep-13	'
Dividend payable date	'	'	'	31-Oct-13	'
Quarter 3 2013 [Member] | OP Units [Member]	'	'	'	'	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'	'	'	'	'
Dividends declared date	'	'	'	18-Sep-13	'
Dividend payable date	'	'	'	31-Oct-13	'
Holders of record date	'	'	'	30-Sep-13	'

Noncontrolling_Interests_Prope

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) (USD $)	9 Months Ended			0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Mar. 26, 2013	Feb. 26, 2013	Feb. 07, 2013	31-May-13
				Transbay Tower [Member]	Transbay Tower [Member]	Transbay Tower [Member]	767 Fifth Avenue (The GM Building) [Member]
				floor			sqft
				sqft
Noncontrolling Interest [Line Items]	'	'	'	'	'	'	'
Partners Joint Venture Ownership Percentage	'	'	'	'	5.00%	50.00%	'
Ownership Percentage	'	'	'	95.00%	95.00%	'	40.00%
Number of floors real estate	'	'	'	60	'	'	'
Net Rentable Area	'	'	'	1,400,000	'	'	1,800,000
Payments to Acquire Land	'	'	'	$192,000,000	'	'	'
Noncontrolling interest recorded upon consolidation	480,861,000	0	'	'	'	'	480,861,000
Noncontrolling interests in property partnerships	$481,629,000	'	($1,964,000)	'	'	'	'

Noncontrolling_Interests_Redee1

Noncontrolling Interests (Redeemable Preferred Units) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Activity of noncontrolling interests	'	'	'	'
Net income	$3,729	$874	$8,796	$2,440
Redeemable Preferred Units [Member]	'	'	'	'
Activity of noncontrolling interests	'	'	'	'
Beginning Balance	'	'	199,378	145,484
Issuance of redeemable preferred units (Series Four Preferred Units)	'	'	'	79,405
Net income	'	'	'	2,440
Contributions On Series Two Preferred Units	'	'	3,385	'
Distributions	'	'	-3,385	-2,440
Redemption of redeemable preferred units (Series Four Preferred Units)	'	'	-43,070	-18,329
Reallocation of partnership interest	'	'	1,425	-908	[1]
Ending Balance	$157,733	$205,652	$157,733	$205,652
[1]	Includes the conversion of 117,407 Series Two Preferred Units into 153,605 OP Units during the nine months ended September 30, 2012.

Noncontrolling_Interests_Nonco

Noncontrolling Interests (Noncontrolling Interests-Redeemable Common Units) (Details) (Noncontrolling Interests [Member], USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Noncontrolling Interests [Member]	'	'
Activity of noncontrolling interests	'	'
Beginning Balance	$1,836,522	$1,809,119
Contributions	26,384	24,653
Net income	74,395	27,386
Distributions	-33,956	-30,100
Conversion of redeemable partnership units	-10,406	-11,236
Unearned compensation	-2,262	-4,832
Accumulated other comprehensive loss	189	208
Adjustments to reflect redeemable partnership units at redemption value	-52,323	187,038
Ending Balance	$1,838,543	$2,002,236

Noncontrolling_Interests_Nonco1

Noncontrolling Interests (Noncontrolling Interests-Property Partnerships) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Activity of noncontrolling interests	'	'	'	'
Beginning balance	'	'	($1,964)	'
Noncontrolling interest recorded upon consolidation	'	'	480,861	0
Capital contributions	'	'	6,386	0
Net Income (loss)	-3,279	458	-924	1,461
Ending balance	481,629	'	481,629	'
Property Partnerships [Member]	'	'	'	'
Activity of noncontrolling interests	'	'	'	'
Beginning balance	'	'	-1,964	-1,063
Noncontrolling interest recorded upon consolidation	'	'	480,861	'
Capital contributions	'	'	10,932	'
Net Income (loss)	'	'	-5,950	1,461
Distributions	'	'	-2,250	-2,250
Ending balance	$481,629	($1,852)	$481,629	($1,852)

Noncontrolling_Interests_Redee2

Noncontrolling Interests Redeemable Interest in Property Partnerships (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Redeemable Interest in Property Partnership [Abstract]	'
Beginning Balance	$97,558
Net loss	-1,523
Distributions	-3,935
Adjustment to reflect redeemable interest at redemption value	6,549
Ending Balance	$98,649

Noncontrolling_Interests_Nonco2

Noncontrolling Interests Noncontrolling interest - Reddemable interest in Property Partnerships (Details) (Fountain Square [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Oct. 04, 2012
Fountain Square [Member]	'
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]	'
Aggregate purchase price	$385
Indebtedness assumed	211.3
Ownership Percentage	50.00%
Payments to Acquire Businesses, Gross	87
Noncontrolling Interest, Ownership Percentage by Parent	50.00%
Future Fixed Price to Acquire Remaining Portion of Joint venture	$102
Fixed Price Option Expiration Date	31-Jan-16

Partners_Capital_Details

Partners' Capital (Details) (USD $)

0 Months Ended

9 Months Ended

9 Months Ended

0 Months Ended

60 Months Ended

9 Months Ended

9 Months Ended

Jul. 31, 2013

Apr. 30, 2013

Mar. 27, 2013

Jan. 29, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 18, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

15-May-13

Mar. 26, 2018

Mar. 27, 2018

Sep. 30, 2013

Sep. 18, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Mar. 27, 2018

Sep. 30, 2013

Sep. 30, 2013

ATM Program [Member]

Issued in conjunction with debt exchange for 3.75% exchangeable senior notes [Member]

Quarter 4 2012 [Member]

Quarter 1 2013 [Member]

Quarter 2 2013 [Member]

Quarter 3 2013 [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Series B Cumulative Redeemable Preferred Stock [Member]

Depository shares of Series B Cumulative Redeemable Preferred [Member]

Depository shares of Series B Cumulative Redeemable Preferred [Member]

OP Units [Member]

Quarter 2 2013 [Member]

Quarter 3 2013 [Member]

Quarter 4 2013 [Member]

Issued in conjunction with debt exchange for 3.75% exchangeable senior notes [Member]

Class of Stock [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

General partnership units (in units)

'

'

'

'

1,695,893

'

'

1,689,580

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Limited partnership units (in units)

'

'

'

'

150,694,702

'

'

149,911,629

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

At the market stock offering program, aggregate value of common stock

'

'

'

'

'

'

'

'

$600,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

At the market stock offering program remaining amount available for issuance

'

'

'

'

'

'

'

'

305,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares of its Common Stock in connection with the redemption of an equal number of OP Units (in shares)

'

'

'

'

336,935

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Dividend payable date

'

'

'

'

'

'

'

'

'

'

29-Jan-13

30-Apr-13

31-Jul-13

31-Oct-13

'

'

'

'

'

'

15-May-13

15-Aug-13

15-Nov-13

'

'

'

Dividend paid on common stock (in dollars per share)

$0.65

$0.65

'

$0.65

'

'

'

'

'

'

'

'

'

'

$32.81

'

'

'

'

'

'

'

'

'

'

'

Dividend shareholder of record date

'

'

'

'

'

'

'

'

'

'

31-Dec-12

29-Mar-13

28-Jun-13

30-Sep-13

'

'

'

'

'

'

'

'

5-Nov-13

'

'

'

Dividends payable, date declared

'

'

'

'

'

'

'

'

'

'

'

'

'

18-Sep-13

'

'

'

'

'

'

'

'

18-Sep-13

'

'

'

Dividends payable (in dollars per share)

'

'

'

'

'

'

$0.65

'

'

'

'

'

'

'

'

'

'

'

$32.81

'

'

'

'

'

'

'

Series B, Units Outstanding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

80,000

'

0

'

'

'

'

8,000,000

'

Series B, Liquidation Preference Per Unit

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$2,500

$2,500

'

$0

'

'

'

$25

$25

'

Proceeds from Issuance of Series B Preferred Stock

'

'

$193,600,000

'

$193,623,000

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Ratio of depository shares to shares of Series B Preferred Stock

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.01

'

'

'

'

'

'

'

'

Series B, Dividend Rate, Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5.25%

'

'

'

'

'

'

'

'

'

'

Shares issued in conjunction with exchange of 3.75% exchangeable senior notes

'

'

'

'

'

'

'

'

'

419,116

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

419,116

Coupon/Stated Rate (percent)

'

'

'

'

'

'

'

'

'

3.75%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Earnings_Per_Common_Unit_Detai

Earnings Per Common Unit (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Redeemable common units (in shares)	16,829,000	17,660,000	16,975,000	17,694,000
Basic Earnings:	'	'	'	'
Income from continuing operations attributable to Boston Properties Limited Partnership, Income (Numerator)	$84,497	$64,684	$628,206	$215,296
Net income attributable to Boston Properties Limited Partnership, Units (Denominator) (in shares)	169,236,000	168,461,000	168,975,000	167,517,000
Inceom (loss) from continuing operations before discontinued operations and allocation of undistributed earnings (dollars per share)	$0.50	'	$3.72	'
Discontinued operations attributable to Boston Properties Limited Partnership, Income (Numerator)	89,643	1,550	112,046	44,041
Discontinued operations attributable to Boston Properties Limited Partnership, Per Unit Amount (in dollars per share)	$0.53	$0.01	$0.66	$0.26
Net income attributable to Boston Properties Limited Partnership	174,140	66,234	740,252	259,337
Allocation of undistributed earnings to participating securities (numerator)	-651	'	-4,183	'
Allocation of undistributed earnings to participating securities (in dollars per shares)	$0	'	($0.02)	'
Net income attributable to Boston Properties Limited Partnership	173,489	'	736,069	'
Net income (in dollars per share)	$1.03	$0.39	$4.36	$1.55
Effect of Dilutive Securities:	'	'	'	'
Stock Based Compensation and Exchangeable Senior Notes, Income (Numerator)	0	0	0	0
Stock Based Compensation and Exchangeable Senior Notes, Units (Denominator) (in shares)	285,000	1,182,000	381,000	655,000
Stock Based Compensation and Exchangeable Senior Notes, Per Unit Amount (in dollars per share)	($0.01)	$0	($0.01)	($0.01)
Diluted Earnings:	'	'	'	'
Diluted Earnings: Net income attributable to Boston Properties Limited Partnership	$173,489	$66,234	$736,069	$259,337
Diluted Earnings: Net income, Units (Denominator) (in shares)	169,521,000	169,643,000	169,356,000	168,172,000
Diluted Earnings: Net income, Per Unit Amount (in dollars per share)	$1.02	$0.39	$4.35	$1.54

Stock_Option_and_Incentive_Pla1

Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

9 Months Ended

In Millions, except Share data, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Apr. 02, 2013

Sep. 30, 2013

Sep. 30, 2012

Restricted Stock [Member]

LTIP Units [Member]

MYLTIP [Member]

LTIPs And Restricted Stock [Member]

LTIPs and OPP Awards [Member]

Non Qualified Stock Options [Member]

Unvested 2011, 2012 OPP Units and 2013 MYLTIP Units [Member]

Chief Executive Officer [Member]

Board of Directors Chairman [Member]

Executive Vice President [Member]

VestingInstallments

Stock Option And Incentive Plan And Stock Purchase Plan [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Method of valuation

'

'

'

'

'

'Monte Carlo simulation method

'

'

'

'The non-qualified stock options granted during the three months ended March 31, 2013 had a weighted-average fair value on the date of grant of $18.64 per option, which was computed using the Black-Scholes option-pricing model utilizing the following weighted-average assumptions: an expected life of 6.3 years, a risk-free interest rate of 1.19%, an expected price volatility of 26% and an expected dividend yield of 3%

'

'

'

'

Shares issued (in shares)

'

'

'

'

36,730

'

'

'

'

'

'

'

'

'

Non-qualified stock options issued (in shares)

'

'

'

'

'

'

'

'

'

252,220

'

50,847

'

'

LTIP units issued (in shares)

'

'

'

'

'

184,733

'

'

'

'

'

24,231

'

'

MYLTIP units issued (in shares)

'

'

'

'

'

'

318,926

'

'

'

'

38,926

'

'

Employee and director payment per share (in dollars per share)

'

'

'

'

$0.01

'

'

'

$0.25

'

'

'

'

'

Vesting annual installments

'

'

'

'

'

'

'

4

'

'

'

'

'

'

Value of shares of common stock

'

'

'

'

$3.90

'

'

'

'

'

'

'

'

'

Employee's weighted average cost per share (in dollars per share)

'

'

'

'

$105.30

'

'

'

'

'

'

'

'

'

Weighted-average grant date fair value (in dollars per share)

'

'

'

'

'

'

'

'

'

$18.46

'

'

'

'

Expected life assumed to calculate per unit fair value per LTIP unit (in years)

'

'

'

'

'

'5 years 8 months 12 days

'

'

'

'6 years 0 months 0 days

'

'

'

'

Risk-free rate

'

'

'

'

'

1.03%

'

'

'

1.11%

'

'

'

'

Expected price volatility

'

'

'

'

'

26.00%

'

'

'

26.00%

'

'

'

'

Expected dividend rate

'

'

'

'

'

'

'

'

'

3.00%

'

'

'

'

Weighted-average exercise price (in dollars per share)

'

'

'

'

'

'

'

'

'

$105.10

'

'

'

'

Value of LTIP units issued

'

'

'

'

'

14.8

'

'

'

'

'

'

'

'

Per unit fair value weighted-average (in dollars per share)

'

'

'

'

'

$96.33

'

'

'

'

'

'

'

'

Stock-based compensation associated with restricted stock, LTIP Units, 2008 OPP Units, 2011 OPP Units, 2012 OPP Units and 2013 MYLTIPS

6.2

6.4

38.1

23.8

'

'

'

'

'

'

'

'

'

2.7

Acceleration of Stock Basec Compensation and Stock Based Compensation Associated with Transition Agreement

'

'

'

'

'

'

'

'

'

'

'

'

20.2

'

Unrecognized compensation expenses

'

'

'

'

'

'

'

$20.20

'

'

$12.70

'

'

'

Weighted-average period (in years)

'

'

'

'

'

'

'

'

'

'

'2 years 9 months 18 days

'

'

'

Stock_Option_and_Incentive_Pla2

Stock Option and Incentive Plan Stock option and incentive plan (Narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Mar. 11, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Jan. 28, 2013

Apr. 02, 2013

Sep. 30, 2013

Jul. 01, 2014

Oct. 01, 2013

Mar. 11, 2013

Mar. 10, 2013

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP Vesting 2016 [Member]

MYLTIP Vesting 2017 [Member]

MYLTIP Vesting 2018 [Member]

Chief Executive Officer [Member]

Board of Directors Chairman [Member]

Board of Directors Chairman [Member]

Board of Directors Chairman [Member]

Board of Directors Chairman [Member]

Board of Directors Chairman [Member]

indices

Cohen & Steers Realty Majors Portfolio Index [Member]

NAREIT Office Index adjusted [Member]

Minimum [Member]

Maximum [Member]

Threshold [Member]

Target [Member]

Exceptional [Member]

High [Member]

MYLTIP [Member]

MYLTIP [Member]

MYLTIP [Member]

Y

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Allocated Share-based Compensation Expense

$6,200,000

$6,400,000

$38,100,000

$23,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Non-qualified stock options issued

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

50,847

'

'

'

'

'

TRS Measurement, Years

'

'

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted Percentage of Index Used to Compare to TRS

'

'

'

'

'

'

50.00%

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Potential Awards Earned

'

'

'

'

'

'

'

'

0

30,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Indices Used to Compare TRS

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of Tiers

'

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amount of Each Tier

'

'

'

'

'

'

'

'

'

'

5,100,000

10,200,000

30,700,000

20,500,000

'

'

'

'

'

'

'

'

'

Percentage of annualized TRS for Reduction of Earned Awards

'

'

'

'

'

2.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage to Cause Some Awards to be Earned Even if on a Relative Basis it Would Not Result in any Earned Awards

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Vesting Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25.00%

25.00%

50.00%

'

'

33.33%

33.33%

'

33.33%

Vesting Date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4-Feb-16

4-Feb-17

4-Feb-18

'

'

'

'

'

'

Distributions Percent Before Measurement Date

'

'

'

'

'

10.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Value of MYLTIP Awards

'

'

'

'

'

9,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

MYLTIP Value Amortized Into Earnings, Years

'

'

'

'

'

5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash Payment Related to Transition Agreement

'

'

'

'

6,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Target Equity Award Compensation Associated with Transition Agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

11,100,000

'

Compensation Expense associated with Transition Agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

11,800,000

'

'

'

'

Acceleration of Stock Based Compensation in Association with Transition Agreement

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$12,900,000

'

'

'

'

LTIP units issued (in shares)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

24,231

'

'

'

'

'

Segment_Information_Schedule_O

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]	'	'	'	'
Interest expense	$122,173	$105,030	$325,746	$308,168
General and administrative expense	24,841	21,617	94,673	72,208
Development and management services	5,479	8,024	22,072	25,733
Rental Revenue: Class A Office	537,080	434,015	1,458,025	1,280,007
Rental Revenue: Office/Technical	15,378	9,786	40,121	29,471
Rental Revenue: Residential	5,493	5,496	16,555	15,013
Rental Revenue: Hotel	10,652	9,359	30,061	26,224
Rental Revenue Total	568,603	458,656	1,544,762	1,350,715
Total revenue	574,082	466,680	1,566,834	1,376,448
Rental Revenue: % of Grand Totals	100.00%	100.00%	100.00%	100.00%
Rental Expenses: Class A Office	193,329	160,088	528,031	461,130
Rental Expenses: Office/Technical	4,114	2,751	10,711	7,976
Rental Expenses: Residential	2,907	2,854	8,470	8,143
Rental Expenses: Hotel	6,580	6,886	20,959	19,601
Rental Expenses: Total	206,930	172,579	568,171	496,850
Rental Expenses: % Of Grand Totals	100.00%	100.00%	100.00%	100.00%
Net Operating Income	361,673	286,077	976,591	853,865
Net Operating Income: % of Grand Totals	100.00%	100.00%	100.00%	100.00%
Income from unconsolidated joint ventures	14,736	9,217	72,240	42,129
Interest and other income	3,879	4,001	6,646	8,029
Gains (Losses) from investments in securities	956	587	1,872	1,202
Gains from early extinguishments of debt	-30	-5,494	122	-4,453
Transaction costs expensed	766	1,140	1,744	3,252
Boston [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Rental Revenue: Class A Office	171,228	161,479	497,584	460,127
Rental Revenue: Office/Technical	5,662	5,539	16,853	16,882
Rental Revenue: Residential	1,125	995	3,257	2,891
Rental Revenue: Hotel	10,652	9,359	30,061	26,224
Rental Revenue Total	188,667	177,372	547,755	506,124
Rental Revenue: % of Grand Totals	33.18%	38.67%	35.46%	37.47%
Rental Expenses: Class A Office	67,798	65,261	196,710	183,601
Rental Expenses: Office/Technical	1,763	1,758	5,177	4,910
Rental Expenses: Residential	466	490	1,316	1,247
Rental Expenses: Hotel	6,580	6,886	20,959	19,601
Rental Expenses: Total	76,607	74,395	224,162	209,359
Rental Expenses: % Of Grand Totals	37.02%	43.11%	39.45%	42.14%
Net Operating Income	112,060	102,977	323,593	296,765
Net Operating Income: % of Grand Totals	30.98%	36.00%	33.14%	34.76%
New York [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Rental Revenue: Class A Office	198,450	120,270	463,851	360,515
Rental Revenue: Office/Technical	0	0	0	0
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Rental Revenue Total	198,450	120,270	463,851	360,515
Rental Revenue: % of Grand Totals	34.90%	26.22%	30.02%	26.69%
Rental Expenses: Class A Office	66,322	41,088	156,414	118,531
Rental Expenses: Office/Technical	0	0	0	0
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	66,322	41,088	156,414	118,531
Rental Expenses: % Of Grand Totals	32.05%	23.81%	27.53%	23.86%
Net Operating Income	132,128	79,182	307,437	241,984
Net Operating Income: % of Grand Totals	36.53%	27.68%	31.48%	28.34%
Princeton [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Rental Revenue: Class A Office	15,636	15,234	46,916	45,701
Rental Revenue: Office/Technical	0	0	0	0
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Rental Revenue Total	15,636	15,234	46,916	45,701
Rental Revenue: % of Grand Totals	2.75%	3.32%	3.04%	3.38%
Rental Expenses: Class A Office	7,033	6,790	21,386	20,889
Rental Expenses: Office/Technical	0	0	0	0
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	7,033	6,790	21,386	20,889
Rental Expenses: % Of Grand Totals	3.40%	3.93%	3.77%	4.20%
Net Operating Income	8,603	8,444	25,530	24,812
Net Operating Income: % of Grand Totals	2.38%	2.95%	2.61%	2.91%
San Francisco [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Rental Revenue: Class A Office	53,841	52,585	159,843	155,353
Rental Revenue: Office/Technical	5,839	148	11,317	344
Rental Revenue: Residential	0	0	0	0
Rental Revenue: Hotel	0	0	0	0
Rental Revenue Total	59,680	52,733	171,160	155,697
Rental Revenue: % of Grand Totals	10.50%	11.50%	11.08%	11.53%
Rental Expenses: Class A Office	20,006	19,530	58,036	56,496
Rental Expenses: Office/Technical	1,287	52	2,439	114
Rental Expenses: Residential	0	0	0	0
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	21,293	19,582	60,475	56,610
Rental Expenses: % Of Grand Totals	10.29%	11.35%	10.64%	11.39%
Net Operating Income	38,387	33,151	110,685	99,087
Net Operating Income: % of Grand Totals	10.62%	11.59%	11.33%	11.60%
Washington, DC [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Rental Revenue: Class A Office	97,925	84,447	289,831	258,311
Rental Revenue: Office/Technical	3,877	4,099	11,951	12,245
Rental Revenue: Residential	4,368	4,501	13,298	12,122
Rental Revenue: Hotel	0	0	0	0
Rental Revenue Total	106,170	93,047	315,080	282,678
Rental Revenue: % of Grand Totals	18.67%	20.29%	20.40%	20.93%
Rental Expenses: Class A Office	32,170	27,419	95,485	81,613
Rental Expenses: Office/Technical	1,064	941	3,095	2,952
Rental Expenses: Residential	2,441	2,364	7,154	6,896
Rental Expenses: Hotel	0	0	0	0
Rental Expenses: Total	35,675	30,724	105,734	91,461
Rental Expenses: % Of Grand Totals	17.24%	17.80%	18.61%	18.41%
Net Operating Income	70,495	62,323	209,346	191,217
Net Operating Income: % of Grand Totals	19.49%	21.78%	21.44%	22.39%
Intersegment Eliminations [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Interest expense	122,173	105,030	325,746	308,168
General and administrative expense	24,841	21,617	94,673	72,208
Development and management services	5,479	8,024	22,072	25,733
Income from unconsolidated joint ventures	14,736	9,217	72,240	42,129
Interest and other income	3,879	4,001	6,646	8,029
Gains (Losses) from investments in securities	956	587	1,872	1,202
Gains from early extinguishments of debt	-30	-5,494	122	-4,453
Transaction costs expensed	$766	$1,140	$1,744	$3,252

Segment_Information_Schedule_O1

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership	'	'	'	'
Net Operating Income	$189,389	$162,735	$494,953	$480,458
Development and management services income	5,479	8,024	22,072	25,733
Income from unconsolidated joint ventures	14,736	9,217	72,240	42,129
Gain on consolidation of joint ventures	-1,810	0	385,991	0
Interest and other income	3,879	4,001	6,646	8,029
Gains (Losses) from investments in securities	956	587	1,872	1,202
Gains from early extinguishments of debt	-30	-5,494	122	-4,453
Gains on sale of real estate from discontinued operations	88,565	0	88,565	38,445
Gain on forgiveness of debt from discontinued operations	0	0	20,736	0
General and administrative expense	24,841	21,617	94,673	72,208
Transaction costs	766	1,140	1,744	3,252
Depreciation and amortization expense	152,156	108,609	402,892	323,680
Interest expense	122,173	105,030	325,746	308,168
Impairment loss	0	0	4,401	0
Impairment loss from discontinued operations	0	0	2,852	0
Noncontrolling interest in property partnerships	-3,279	458	-924	1,461
Noncontrolling interest-redeemable preferred units	3,729	874	8,796	2,440
Net income attributable to Boston Properties Limited Partnership	174,140	66,234	740,252	259,337
Intersegment Eliminations [Member]	'	'	'	'
Reconciliation of Net Operating Income to net income attributable to Boston Properties Limited Partnership	'	'	'	'
Net Operating Income	361,673	286,077	976,591	853,865
Development and management services income	5,479	8,024	22,072	25,733
Income from unconsolidated joint ventures	14,736	9,217	72,240	42,129
Gain on consolidation of joint ventures	-1,810	0	385,991	0
Interest and other income	3,879	4,001	6,646	8,029
Gains (Losses) from investments in securities	956	587	1,872	1,202
Gains from early extinguishments of debt	-30	-5,494	122	-4,453
Income from discontinued operations	1,078	1,550	5,597	5,596
Gains on sale of real estate from discontinued operations	88,565	0	88,565	38,445
Gain on forgiveness of debt from discontinued operations	0	0	20,736	0
General and administrative expense	24,841	21,617	94,673	72,208
Transaction costs	766	1,140	1,744	3,252
Depreciation and amortization expense	152,156	108,609	402,892	323,680
Interest expense	122,173	105,030	325,746	308,168
Impairment loss	0	0	4,401	0
Impairment loss from discontinued operations	0	0	2,852	0
Noncontrolling interest in property partnerships	-3,279	458	-924	1,461
Noncontrolling interest-redeemable preferred units	3,729	874	8,796	2,440
Net income attributable to Boston Properties Limited Partnership	$174,140	$66,234	$740,252	$259,337

Segment_Information_Segment_In

Segment Information Segment Information (narrative) (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

31-May-13

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

767 Fifth Avenue (The GM Building) [Member]

Princeton [Member]

Princeton [Member]

Princeton [Member]

Princeton [Member]

San Francisco [Member]

San Francisco [Member]

San Francisco [Member]

San Francisco [Member]

partners

Segment Reporting Information [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Reclassification between general and administrative expense and real estate operating expense

$2

$1.90

$6.10

$5.80

'

$0.30

$0.40

$1.30

$1.40

$1.70

$1.50

$4.80

$4.40

Number of Joint Venture Partners

'

'

'

'

2

'

'

'

'

'

'

'

'

Subsequent_Events_Subsequent_E

Subsequent Events Subsequent Events (Details) (USD $)	Oct. 09, 2013	Oct. 29, 2013	Oct. 29, 2013	Apr. 04, 2013	Sep. 26, 2013	Oct. 21, 2013	Sep. 30, 2012	Oct. 21, 2013	Sep. 30, 2012	Oct. 29, 2013
In Millions, except Share data, unless otherwise specified	Time Square Tower [Member]	Princeton Build to Suit [Member]	Annapolis Junction Building Seven [Member]	Annapolis Junction Building Seven [Member]	Annapolis Junction Building Seven [Member]	Series Two Preferred Units [Member]	Series Two Preferred Units [Member]	OP Units [Member]	OP Units [Member]	Prior to extension [Member]
	sqft	sqft	sqft		sqft					Annapolis Junction Building Seven [Member]
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'	'	'
Debt Instrument, Description of Variable Rate Basis	'	'	'LIBOR plus 1.65%	'	'	'	'	'	'	'
Ownership Percentage	45.00%	'	'	'	'	'	'	'	'	'
Net Rentable Area	1,246,000	130,000	119,000	'	125,000	'	'	'	'	'
Conversion of Stock, Shares Converted	'	'	'	'	'	329,881	117,407	432,914	153,605	'
Contractual Sales Price	$684	'	'	'	'	'	'	'	'	'
Proceeds from sale of an interest in a real estate asset	673.4	'	'	'	'	'	'	'	'	'
Equity Method Investment, Ownership Percentage	'	'	50.00%	50.00%	50.00%	'	'	'	'	'
Maturity date	'	'	17-Nov-14	4-Apr-16	'	'	'	'	'	17-Nov-13
Construction Loan	'	'	$14	'	'	'	'	'	'	'
Debt Instrument, Basis Spread on Variable Rate	'	'	1.65%	1.65%	'	'	'	'	'	'