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Real Estate, Number Of Properties Acquired

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Related Party Transaction, Area of Real Estate Acquired

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Amount of amortization of acquired leases acquired as part of a real property acquisition at below market lease rate with a finite life.

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Area of a real estate property.

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Amount of accumulated amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

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Amount before amortization of leases acquired as part of a real property acquisition at below market lease rate with a finite life.

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Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount before accumulated deprecation and depletion of real estate held for productive use and additions or improvements to real estate held for productive use, examples include, but are not limited to, walkways, driveways, fences, and parking lots. Excludes land held for sale.

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Amount of increase (decrease) in investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

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The number of shares issued as [noncash or part noncash] consideration for a business or asset acquired. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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The value of an asset or business acquired in a noncash (or part noncash) acquisition. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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The number of units in a real estate property owned as of the balance sheet date.

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Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

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The cash outflow from the acquisition of a piece of land, anything permanently fixed to it, including buildings, structures on it and so forth; includes real estate intended to generate income for the owner; excludes real estate acquired for use by the owner.

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Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Amount of real estate owned for income production and capital accretion potential, not otherwise specified in the existing taxonomy. Such real estate excludes that which is occupied or used in the business, for entertainment purposes, or held in inventory for specific purposes.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Real Estate Acquired - Additional Information (Detail) ft² in Thousands		1 Months Ended									3 Months Ended	12 Months Ended
	May 09, 2018 shares	Dec. 31, 2018 USD ($) ft² apartment	Sep. 30, 2018 USD ($)	May 31, 2018 USD ($) a shares	Mar. 31, 2017 USD ($)	Jan. 31, 2017 USD ($)	Aug. 31, 2016 USD ($) a	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Aug. 31, 2014 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 USD ($) ft² apartment	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Payments to acquire real estate												$ 12,883,000	$ 17,653,000	$ 15,564,000
Acquisition costs				$ 200,000										60,400
Rent expense												779,800	$ 774,700	843,300
Area of real estate property (in square feet) \| a				13,700			13,700
Number of properties acquired \| property													1
Purchase price allocated to land		$ 488,918,000										488,918,000
Purchase price allocated to buildings		1,273,275,000										1,273,275,000
Below market lease, carrying amount		24,800,000										24,800,000	$ 25,100,000
Below market lease, accumulated amortization		13,100,000										13,100,000	11,800,000
Accretion income, intangible liabilities												1,700,000	1,700,000	1,800,000
Total Purchase Price		1,948,165,000									$ 1,700,813,000	1,948,165,000	1,803,200,000	1,700,813,000	$ 1,622,710,000
Lease acquisition costs
Real Estate Properties [Line Items]
Intangible assets gross carrying amount		12,500,000										12,500,000	12,300,000
Intangible assets, accumulated amortization		8,100,000										8,100,000	7,500,000
Amortization expense												$ 1,300,000	1,100,000	1,000,000
Weighted-average amortization period												4 years 1 month 6 days
Above Market Rent
Real Estate Properties [Line Items]
Intangible assets gross carrying amount		800,000										$ 800,000	600,000
Intangible assets, accumulated amortization		100,000										100,000	39,500
Amortization expense												$ 110,500	31,600	1,500
Weighted-average amortization period												7 years 2 months 12 days
Below Market Rent
Real Estate Properties [Line Items]
Weighted-average amortization period												5 years 6 months
750 N. Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate										$ 40,000,000
Acquisition costs										$ 400,000
730 N. Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate									$ 2,800,000
Acquisition costs									$ 40,400
726 N Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate								$ 4,000,000
Acquisition costs								$ 100,000
700 N. Glebe Road
Real Estate Properties [Line Items]
Payments to acquire real estate							$ 7,200,000
Purchase price allocated to land											7,236,000			7,236,000
Purchase price allocated to buildings											0			0
Total Purchase Price											7,236,000			7,236,000
700 N. Glebe Road \| In-place Leases
Real Estate Properties [Line Items]
Intangible assets											0			0
700 N. Glebe Road \| Above Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
700 N. Glebe Road \| Below Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
Thruway Pad
Real Estate Properties [Line Items]
Payments to acquire real estate							3,100,000
Acquisition costs							$ 60,400
Purchase price allocated to land											2,196,000			2,196,000
Purchase price allocated to buildings											874,000			874,000
Total Purchase Price											3,100,000			3,100,000
Thruway Pad \| In-place Leases
Real Estate Properties [Line Items]
Intangible assets											93,000			93,000
Thruway Pad \| Above Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
Thruway Pad \| Below Market Rent
Real Estate Properties [Line Items]
Intangible assets											63,000			63,000
Beacon Center
Real Estate Properties [Line Items]
Payments to acquire real estate											22,700,000
Rent expense											60,000
Mortgage loans on real estate, period increase (decrease)											11,250,000
Southdale
Real Estate Properties [Line Items]
Payments to acquire real estate											15,300,000
Rent expense											60,000
Burtonsville Town Square
Real Estate Properties [Line Items]
Payments to acquire real estate						$ 76,400,000							76,400,000
Purchase price allocated to land													28,400,000
Purchase price allocated to buildings													45,800,000
Burtonsville Town Square \| In-place Leases
Real Estate Properties [Line Items]
Intangible assets													2,200,000
Burtonsville Town Square \| Above Market Rent
Real Estate Properties [Line Items]
Intangible assets													600,000
Burtonsville Town Square \| Below Market Rent
Real Estate Properties [Line Items]
Intangible assets													$ 600,000
2016 Acquisitions
Real Estate Properties [Line Items]
Payments to acquire real estate														10,300,000
Purchase price allocated to land											9,432,000			9,432,000
Purchase price allocated to buildings											874,000			874,000
Total Purchase Price											10,336,000			10,336,000
2016 Acquisitions \| In-place Leases
Real Estate Properties [Line Items]
Intangible assets											93,000			93,000
2016 Acquisitions \| Above Market Rent
Real Estate Properties [Line Items]
Intangible assets											0			0
2016 Acquisitions \| Below Market Rent
Real Estate Properties [Line Items]
Intangible assets											$ 63,000			$ 63,000
Olney
Real Estate Properties [Line Items]
Payments to acquire real estate					$ 3,100,000
Rent expense					$ 56,000
2018 Acquisitions
Real Estate Properties [Line Items]
Purchase price allocated to land		47,438,000										$ 47,438,000
Purchase price allocated to buildings		979,000										979,000
Total Purchase Price		49,450,000										49,450,000
2018 Acquisitions \| In-place Leases
Real Estate Properties [Line Items]
Intangible assets		886,000										886,000
2018 Acquisitions \| Above Market Rent
Real Estate Properties [Line Items]
Intangible assets		168,000										168,000
2018 Acquisitions \| Below Market Rent
Real Estate Properties [Line Items]
Intangible assets		21,000										$ 21,000
Ashbrook Marketplace
Real Estate Properties [Line Items]
Limited partnership units issued				$ 8,776,000
7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Payments to acquire real estate			$ 35,500,000
Acquisition costs			$ 700,000
Parcel Adjacent to 7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Payments to acquire real estate		$ 4,500,000
7316 Wisconsin Avenue Retail Space
Real Estate Properties [Line Items]
Area of real estate property (in acres) \| ft²		10										10
BF Saul Real Estate Investment Trust \| Ashbrook Marketplace
Real Estate Properties [Line Items]
Limited partnership units issued (in shares) \| shares	176,680			176,680
Maximum \| 7316 Wisconsin Avenue
Real Estate Properties [Line Items]
Number of units in real estate property \| apartment		325										325
Maximum \| 7316 Wisconsin Avenue Additional Apartment Units
Real Estate Properties [Line Items]
Number of units in real estate property \| apartment		40										40