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Noncontrolling Interests - Holders of Convertible Limited Partnership Units in the Operating Partnership (Details) - Noncontrolling Interests shares in Millions	3 Months Ended
	Mar. 31, 2021 shares	Mar. 31, 2020 shares
Noncontrolling Interest [Line Items]
Limited partnership units (in shares)	8.0
Limited partnership units, conversion ratio	1
Outstanding stock percent that should be acquired for rights to be exercised	39.90%
Limited partnership units convertible into shares of common stock, eligible for conversion	1.3
Fully converted partnership units and diluted weighted average shares outstanding	32.0	31.2
Partners capital account units placed In escrow	1.4
Saul Holdings Limited Partnership
Noncontrolling Interest [Line Items]
Percentage of ownership interest of noncontrolling interest	25.30%

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- Definition

Limited Partners' Capital Account, Convertible Units, Conversion Ratio

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- Definition

Limited Partners' Capital Account, Convertible Units, Eligible for Conversion

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- Definition

Minimum Outstanding Stock Percentage That Should be Acquired for Rights Issued to Become Exercisable

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- Definition

Partners' Capital Account, Units, Converted and Weighted Average Shares Outstanding, Diluted

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- Definition

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- Definition

The number of limited partner units outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187171-122770

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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