IDENTIFIED INTANGIBLE ASSETS AND LIABILITIES - Schedule of Estimated Annual Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired below-market leases, net of above-market leases	$ 2,300	$ 2,100	$ 6,800	$ 13,900
Below-Market Operating Lease Amortization
Reminder of 2019	2,430		2,430
2019	9,681		9,681
2020	9,605		9,605
2021	9,559		9,559
2022	9,324		9,324
2024	9,151		9,151
In-Place Leases
Amortization of Intangible Assets	2,100	$ 1,700	6,300	$ 5,700
Above-Market
Above-Market Operating Lease Amortization
Remainder of 2019	(257)		(257)
2020	(860)		(860)
2021	(495)		(495)
2022	(386)		(386)
2023	(321)		(321)
2024	(142)		(142)
In-Place Leases
Remainder of 2019	(257)		(257)
2020	(860)		(860)
2021	(495)		(495)
2022	(386)		(386)
2023	(321)		(321)
2024	(142)		(142)
Amortization
Above-Market Operating Lease Amortization
Remainder of 2019	(2,174)		(2,174)
2020	(7,595)		(7,595)
2021	(5,995)		(5,995)
2022	(4,859)		(4,859)
2023	(4,366)		(4,366)
2024	(3,732)		(3,732)
In-Place Leases
Remainder of 2019	(2,174)		(2,174)
2020	(7,595)		(7,595)
2021	(5,995)		(5,995)
2022	(4,859)		(4,859)
2023	(4,366)		(4,366)
2024	$ (3,732)		$ (3,732)

Amortization Of Acquired Below-Market Lease, Net Of Acquired Above-Market Lease

No definition available.

Name:	ue_AmortizationOfAcquiredBelowMarketLeaseNetOfAcquiredAboveMarketLease
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Below Market Lease, Net Of Above Market Lease, Amortization Income, Reminder of Fiscal Year

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetOfAboveMarketLeaseAmortizationIncomeReminderofFiscalYear
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Below Market Lease, Net Of Above Market Lease, Amortization Income, Year Five

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetOfAboveMarketLeaseAmortizationIncomeYearFive
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Below Market Lease, Net Of Above Market Lease, Amortization Income, Year Four

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetOfAboveMarketLeaseAmortizationIncomeYearFour
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Below Market Lease, Net Of Above Market Lease, Amortization Income, Year Six

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetOfAboveMarketLeaseAmortizationIncomeYearSix
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Below Market Lease, Net Of Above Market Lease, Amortization Income, Year Three

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetOfAboveMarketLeaseAmortizationIncomeYearThree
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Below Market Lease, Net Of Above Market Lease, Amortization Income, Year Two

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetOfAboveMarketLeaseAmortizationIncomeYearTwo
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Below Market Lease, Net of Above Market Lease, Amortization Income, Fiscal Year Maturity [Abstract]

+ References

No definition available.

+ Details

Name:	ue_BelowMarketLeaseNetofAboveMarketLeaseAmortizationIncomeFiscalYearMaturityAbstractAbstract
Namespace Prefix:	ue_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Finite-Lived Intangible Assets, Amortization Expense, Year Six

+ References

No definition available.

+ Details

Name:	ue_FiniteLivedIntangibleAssetsAmortizationExpenseYearSix
Namespace Prefix:	ue_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

+ Details

Name:	us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_BelowMarketLeaseNetAmortizationIncomeFiscalYearMaturityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized in the remainder of the fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsFutureAmortizationExpenseAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_AboveMarketLeasesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LeasesAcquiredInPlaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: