IDENTIFIED INTANGIBLE ASSETS AND LIABILITIES - Schedule of Estimated Annual Amortization Expense (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Below-Market Operating Lease Amortization
Reminder of 2019	$ 7,367
2019	9,703
2020	9,627
2021	9,575
2022	9,339
2024	9,167
Above-Market
Above-Market Operating Lease Amortization
Remainder of 2019	(778)
2020	(860)
2021	(495)
2022	(386)
2023	(321)
2024	(142)
In-Place Leases
Remainder of 2019	(778)
2020	(860)
2021	(495)
2022	(386)
2023	(321)
2024	(142)
In-Place Leases
Above-Market Operating Lease Amortization
Remainder of 2019	(6,565)
2020	(7,612)
2021	(6,005)
2022	(4,859)
2023	(4,366)
2024	(3,732)
In-Place Leases
Remainder of 2019	(6,565)
2020	(7,612)
2021	(6,005)
2022	(4,859)
2023	(4,366)
2024	$ (3,732)

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

No definition available.

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

- 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

- 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: