Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment [Table Text Block]

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:

Land improvements	25 to 40 years
Buildings and improvements	10 to 40 years
Tenant improvements	Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment	3 to 7 years

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).

	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2018	$	8,614	$	32,152
2019	7,106		27,281
2020	5,394		10,736
2021	2,988		6,399
2022	315		5,669

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).

	Acquired In-Place Lease Intangibles
2018	$	33,651
2019	27,333
2020	14,464
2021	8,777
2022	4,758

Schedule Of Future Contractual Minimum Lease Payments Under Non-Cancelable Ground Leases [Table Text Block]

The future contractual minimum lease payments to be made by the Company as of December 31, 2017, under non-cancelable ground leases which expire on various dates through 2114, are as follows:

Years Ending December 31,	(in thousands)
2018	$	11,349
2019	16,360
2020	25,552
2021	11,814
2022	8,894
Thereafter	576,315

Capital Leases in Financial Statements of Lessee Disclosure [Text Block]

The following reflects the gross amount of assets recorded under capital leases by asset class at December 31, 2017 and December 31, 2016 (in thousands):

	December 31,
	2017		2016
Buildings and improvements	$	23,636	$	23,636
Construction in progress	28,962		—
Total	$	52,598	$	23,636

The future minimum lease payments, as of December 31, 2017, related to the three capital leases, through 2036 are as follows:

Years Ending December 31,	(in thousands)
2018	$	913
2019	1,392
2020	2,097
2021	1,375
2022	930
Thereafter	74,185
Total expected minimum lease payments	80,892
Interest portion	(29,296		)
Present value of expected net minimum lease payments	$	51,596

Fair Value, by Balance Sheet Grouping [Table Text Block]

The following table presents the aggregate carrying value of the Company’s mortgage notes payable, net, mezzanine notes payable, unsecured senior notes, net and unsecured line of credit and the Company’s corresponding estimate of fair value as of December 31, 2017 and December 31, 2016 (in thousands):

	December 31, 2017				December 31, 2016
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Mortgage notes payable, net	$	2,979,281	$	3,042,920	$	2,063,087	$	2,092,237
Mezzanine notes payable	—		—		307,093		308,344
Unsecured senior notes, net	7,247,330		7,461,615		7,245,953		7,428,077
Unsecured line of credit	45,000		45,000		—		—
Total	$	10,271,611	$	10,549,535	$	9,616,133	$	9,828,658

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes, Table [Table Text Block]

The tax treatment of common dividends per share for federal income tax purposes is as follows: 

	For the year ended December 31,
	2017					2016					2015
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.86		98.29	%	$	2.76		90.51	%	$	2.34		57.97	%
Capital gain income	0.05			1.71	%	0.29			9.49	%	1.70			42.03	%
Total	$	2.91	(1)	100.00	%	$	3.05	(2)	100.00	%	$	4.04	(3)	100.00	%

_____________

(1) The fourth quarter 2017 regular quarterly dividend was $0.80 per common share of which approximately $0.47 per common share was allocable to 2017 and approximately $0.33 per common share is allocable to 2018.

(2) The fourth quarter 2016 regular quarterly dividend was $0.75 per common share of which approximately $0.56 per common share was allocable to 2016 and approximately $0.19 per common share is allocable to 2017.

(3) The fourth quarter 2015 dividend of $1.90 per common share consists of a $1.25 per common share special dividend and a $0.65 per common share regular quarterly dividend. Approximately $1.35 per common share was allocable to 2015 and approximately $0.55 per common share is allocable to 2016.

Gaap Reconciliation Of Net Income To Taxable Income, Table [Table Text Block]

The following table reconciles GAAP net income attributable to Boston Properties, Inc. to taxable income (unaudited): 

	For the year ended December 31,
	2017			2016			2015
	(in thousands)
Net income attributable to Boston Properties, Inc.	$	462,439		$	512,785		$	583,106
Straight-line rent and net “above-” and “below-market” rent adjustments	(77,801		)	(65,861		)	(92,483		)
Book/Tax differences from depreciation and amortization	142,234			235,819			307,115
Book/Tax differences from interest expense	(18,136		)	(36,223		)	(43,349		)
Book/Tax differences on gains/(losses) from capital transactions	1,123			(70,880		)	(74,482		)
Book/Tax differences from stock-based compensation	37,990			33,463			22,008
Tangible Property Regulations	(116,265		)	(104,783		)	(74,887		)
Other book/tax differences, net	33,411			(6,121		)	(15,259		)
Taxable income	$	464,995		$	498,199		$	611,769

Boston Properties Limited Partnership

Summary Of Significant Accounting Policies [Line Items]

Gaap Reconciliation Of Net Income To Taxable Income, Table [Table Text Block]

The following table reconciles GAAP net income attributable to Boston Properties Limited Partnership to taxable income (unaudited):

	For the year ended December 31,
	2017			2016			2015
	(in thousands)
Net income attributable to Boston Properties Limited Partnership	$	523,366		$	585,841		$	659,248
Straight-line rent and net “above-” and “below-market” rent adjustments	(86,773		)	(73,604		)	(103,227		)
Book/Tax differences from depreciation and amortization	144,436			245,239			329,629
Book/Tax differences from interest expense	(20,227		)	(40,481		)	(48,385		)
Book/Tax differences on gains/(losses) from capital transactions	784			(69,683		)	(67,602		)
Book/Tax differences from stock-based compensation	42,371			37,397			24,565
Tangible Property Regulations	(129,673		)	(117,102		)	(83,587		)
Other book/tax differences, net	37,607			(3,387		)	(14,561		)
Taxable income	$	511,891		$	564,220		$	696,080