Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Income per Common Unit of the Operating Partnership - Anti-dilutive Options (Details) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Stock Option
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive options excluded from computation of earnings per share	0	0	0	0
Liberty Property Limited Partnership \| Stock Option
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive options excluded from computation of earnings per share	0	0	0	0
Common Units \| 2017 Share Repurchase Program \| Liberty Property Limited Partnership
Antidilutive Options Excluded from Computation of Earnings Per Share [Line Items]
Stock repurchased in period (in shares)	0		0		0