Real Estate Investments - Schedule of Business Acquisitions (Details) $ in Thousands	3 Months Ended
Mar. 31, 2022 USD ($)
Business Acquisition [Line Items]
Purchase Price	$ 94,030
Debt Assumed, Net of Discounts	22,074
Consolidated Properties [Member]
Business Acquisition [Line Items]
Purchase Price	41,650
Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Purchase Price	52,380
Debt Assumed, Net of Discounts	22,074
Off-Market Favorable Lease [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	7,236
Off-Market Favorable Lease [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	2,900
Off-Market Favorable Lease [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	4,336
Off-Market Lease, Unfavorable [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	7,653
Off-Market Lease, Unfavorable [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	6,839
Off-Market Lease, Unfavorable [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 814
Glenwood Green [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	Mar. 01, 2022
Property Name	Glenwood Green
City/State	Old Bridge, NJ
Ownership	70.00%
Purchase Price	$ 11,000
Island Village [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	Mar. 31, 2022
Property Name	Island Village
City/State	Bainbridge Island, WA
Ownership	100.00%
Purchase Price	$ 30,650
Island Village [Member] \| Off-Market Favorable Lease [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	2,900
Island Village [Member] \| Off-Market Lease, Unfavorable [Member] \| Consolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 6,839
Naperville Plaza [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Date Purchased	Mar. 25, 2022
Property Name	Naperville Plaza
City/State	Naperville, IL
Ownership	20.00%
Purchase Price	$ 52,380
Debt Assumed, Net of Discounts	22,074
Naperville Plaza [Member] \| Off-Market Favorable Lease [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	4,336
Naperville Plaza [Member] \| Off-Market Lease, Unfavorable [Member] \| Unconsolidated Properties [Member]
Business Acquisition [Line Items]
Intangible Assets/Liabilities	$ 814

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 7
-URI https://asc.fasb.org/extlink&oid=123586518&loc=d3e848-128460

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=123586518&loc=d3e845-128460

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ 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

No definition available.

+ 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-URI https://asc.fasb.org/extlink&oid=123455525&loc=d3e2207-128464

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=128092470&loc=d3e4845-128472

+ 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=128092470&loc=d3e4845-128472

+ 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI https://asc.fasb.org/extlink&oid=126975305&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3213-108585

+ 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_GlenwoodGreenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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