Summary of Significant Accounting Policies - Properties in Development (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2014
Development in Process	$ 239,538,000us-gaap_DevelopmentInProcess	$ 186,450,000us-gaap_DevelopmentInProcess
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	463,537,000
Other Cost and Expense, Operating	2,300,000us-gaap_OtherCostAndExpenseOperating	528,000us-gaap_OtherCostAndExpenseOperating	1,500,000us-gaap_OtherCostAndExpenseOperating
Impairment of Real Estate	1,257,000us-gaap_ImpairmentOfRealEstate	6,000,000us-gaap_ImpairmentOfRealEstate	74,816,000us-gaap_ImpairmentOfRealEstate
Impairment Losses Related to Real Estate Partnerships	(1,300,000)	(5,880,000)
Deferred Costs, Leasing, Net	60,889,000us-gaap_DeferredCostsLeasingNet	59,027,000us-gaap_DeferredCostsLeasingNet
Deferred Finance Costs, Net	10,613,000us-gaap_DeferredFinanceCostsNet	10,936,000us-gaap_DeferredFinanceCostsNet
Deferred costs, less accumulated amortization of $73,231 and $69,224 at December 31, 2013 and 2012, respectively	71,502,000us-gaap_DeferredCosts	69,963,000us-gaap_DeferredCosts
Discontinued operations
Property, Plant and Equipment [Line Items]
Impairment of Real Estate	0	0	54,500,000
Properties in Development [Member]
Property, Plant and Equipment [Line Items]
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	1,769,000	3,495,000
Refundable deposits - development
Property, Plant and Equipment [Line Items]
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	375,000	680,000
Construction in Progress
Property, Plant and Equipment [Line Items]
Development in Process	213,526,000	158,002,000
Land Held for Future Development
Property, Plant and Equipment [Line Items]
Development in Process	$ 24,243,000	$ 24,953,000
Minimum [Member] \| Construction in Progress
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Development in Process, Percentage Leased	90.00%
Time Period In Which Anchor Has Been Open But Still Considered Construction In Process	1 year
Maximum [Member] \| Construction in Progress
Property, Plant and Equipment [Line Items]
Percentage Of Expected Costs	90.00%
Property, Plant and Equipment, Development in Process, Percentage Leased	95.00%
Time Period In Which Anchor Has Been Open But Still Considered Construction In Process	2 years
Property, Plant and Equipment, Development in Process, Period Since Start of Construction	3 years

End date of current fiscal year in the format --MM-DD.

No definition available.

Name:	dei_CurrentFiscalYearEndDate
Namespace Prefix:	dei_
Data Type:	xbrli:gMonthDayItemType
Balance Type:	na
Period Type:	duration

- Definition

This is focus fiscal year of the document report in CCYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.

+ References

No definition available.

+ Details

Name:	dei_DocumentFiscalYearFocus
Namespace Prefix:	dei_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Property, Plant and Equipment, Development in Process, Anchor Operations Period"

+ References

No definition available.

+ Details

Name:	reg_PropertyPlantAndEquipmentDevelopmentInProcessAnchorOperationsPeriod
Namespace Prefix:	reg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Property, Plant and Equipment, Development in Process, Percentage Complete

+ References

No definition available.

+ Details

Name:	reg_PropertyPlantAndEquipmentDevelopmentInProcessPercentageComplete
Namespace Prefix:	reg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Property, Plant and Equipment, Development in Process, Percentage Leased

+ References

No definition available.

+ Details

Name:	reg_PropertyPlantandEquipmentDevelopmentinProcessPercentageLeased
Namespace Prefix:	reg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Property, Plant and Equipment, Development in Process, Period Since Start of Construction

+ References

No definition available.

+ Details

Name:	reg_PropertyPlantandEquipmentDevelopmentinProcessPeriodSinceStartofConstruction
Namespace Prefix:	reg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Sum of the carrying amounts of deferred costs that are expected to be recognized as a charge against earnings in periods after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.10)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

This element represents costs incurred by the lessor that are (a) costs to originate a lease incurred in transactions with independent third parties that (i) result directly from and are essential to acquire that lease and (ii) would not have been incurred had that leasing transaction not occurred and (b) certain costs directly related to specified activities performed by the lessor for that lease. Those activities are: evaluating the prospective lessee's financial condition; evaluating and recording guarantees, collateral, and other security arrangements; negotiating lease terms; preparing and processing lease documents; and closing the transaction. This element is net of accumulated amortization.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=6748888&loc=d3e40246-112709

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 35

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6453741&loc=d3e40879-112712

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=6748888&loc=d3e40588-112709

+ Details

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

- Definition

For an unclassified balance sheet, the carrying amount (net of accumulated amortization) as of the balance sheet date of capitalized costs associated with the issuance of debt instruments (for example, legal, accounting, underwriting, printing, and registration costs) that will be charged against earnings over the life of the debt instruments to which such costs pertain.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

+ Details

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

- Definition

The current amount of expenditures for a real estate project that has not yet been completed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.10)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Impairment losses measured as the amount by which the carrying amount of the business or real estate partnerships exceeds the fair value of the business or partnership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230

+ Details

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

- Definition

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

+ References

+ Details

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

- Definition

The total amount of other operating cost and expense items that are associated with the entity's normal revenue producing operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 3

-Article 5

+ Details

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

- Details

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

- Definition

Amount of carrying costs of properties that were capitalized after acquisition, for example, but not limited to, real estate taxes and insurance for entities with a substantial portion of business acquiring and holding investment real estate. Excludes initial purchase price and improvements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 970

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-28)

-URI http://asc.fasb.org/extlink&oid=6590653&loc=d3e638233-123024

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule III)

-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

-Article 5

+ Details

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

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=reg_LandHeldForFutureDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=reg_PropertiesInDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=reg_RefundableDepositsDevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_ConstructionInProgressMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_SegmentDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: