Real Estate Investments - Schedule of Properties Acquired (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Business Acquisition [Line Items]
Purchase Price	$ 179,950	$ 53,500
Debt Assumed, Net of Discounts	68,693	0
Consolidated Properties [Member]
Business Acquisition [Line Items]
Purchase Price	153,700
Debt Assumed, Net of Discounts	56,809
Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Purchase Price	26,250
Debt Assumed, Net of Discounts	11,884
Off-Market Favorable Lease [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	16,438	5,360
Off-Market Favorable Lease [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	14,033
Off-Market Favorable Lease [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	2,405
Off-Market Lease, Unfavorable [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	24,552	$ 2,175
Off-Market Lease, Unfavorable [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	19,054
Off-Market Lease, Unfavorable [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 5,498
Putnam Plaza [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	Jan. 01, 2025
Property Name	Putnam Plaza
City/State	Carmel Hamlet, NY
Ownership	100.00%
Purchase Price	$ 31,000
Debt Assumed, Net of Discounts	16,749
Putnam Plaza [Member] \| Off-Market Favorable Lease [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	4,308
Putnam Plaza [Member] \| Off-Market Lease, Unfavorable [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 460
Orange Meadows [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	Jan. 10, 2025
Property Name	Orange Meadows
City/State	Orange, CT
Ownership	100.00%
Purchase Price	$ 4,200
Debt Assumed, Net of Discounts	0
Orange Meadows [Member] \| Off-Market Favorable Lease [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	354
Orange Meadows [Member] \| Off-Market Lease, Unfavorable [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 299
Brentwood Place [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	Mar. 14, 2025
Property Name	Brentwood Place
City/State	Nashville, TN
Ownership	100.00%
Purchase Price	$ 118,500
Debt Assumed, Net of Discounts	40,060
Brentwood Place [Member] \| Off-Market Favorable Lease [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	9,371
Brentwood Place [Member] \| Off-Market Lease, Unfavorable [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 18,295
Armonk Square [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	May 12, 2025
Property Name	Armonk Square
City/State	Armonk, NY
Ownership	20.00%
Purchase Price	$ 26,250
Debt Assumed, Net of Discounts	11,884
Armonk Square [Member] \| Off-Market Favorable Lease [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	2,405
Armonk Square [Member] \| Off-Market Lease, Unfavorable [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 5,498
The Shops at Stone Bridge [Member]
Business Acquisition [Line Items]
Date Purchased		Feb. 23, 2024
Property Name		The Shops at Stone Bridge
City/State		Cheshire, CT
Ownership		100.00%
Purchase Price		$ 8,000
Debt Assumed, Net of Discounts		0
The Shops at Stone Bridge [Member] \| Off-Market Favorable Lease [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities		0
The Shops at Stone Bridge [Member] \| Off-Market Lease, Unfavorable [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities		$ 0
Compo Acres North Shopping Center [Member]
Business Acquisition [Line Items]
Date Purchased		May 03, 2024
Property Name		Compo Acres North shopping center
City/State		Westport, CT
Ownership		100.00%
Purchase Price		$ 45,500
Debt Assumed, Net of Discounts		0
Compo Acres North Shopping Center [Member] \| Off-Market Favorable Lease [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities		5,360
Compo Acres North Shopping Center [Member] \| Off-Market Lease, Unfavorable [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities		$ 2,175

Business Acquisition Location, City and State

No definition available.

Name:	reg_BusinessAcquisitionLocationCityAndState
Namespace Prefix:	reg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the acquirer obtains control of the acquiree, in YYYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 25
-Paragraph 7
-SubTopic 10
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479405/805-10-25-7

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-SubTopic 10
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 25
-Paragraph 6
-SubTopic 10
-Topic 805
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479405/805-10-25-6

+ Details

Name:	us-gaap_BusinessAcquisitionEffectiveDateOfAcquisition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-5

+ Details

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

- Definition

Name of the acquired entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

+ Details

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

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

+ Details

Name:	us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of identifiable intangible assets recognized as of the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479303/805-10-55-37

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

+ Details

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

- Definition

Amount of liabilities assumed at the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479581/805-30-50-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-13

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_ConsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_UnconsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	reg_FiniteLivedIntangibleLiabilitiesAxis=reg_OffMarketLeaseUnfavorableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=reg_PutnamPlazaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=reg_OrangeMeadowsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=reg_BrentwoodPlaceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=reg_ArmonkSquareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=reg_TheShopsAtStoneBridgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=reg_CompoAcresNorthShoppingCenterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: