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.

No definition available.

+ Details

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

- Definition

Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624171-113959

+ Details

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

- Definition

Amount of liability hedged in fair value hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL109999712-113959

+ Details

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

- Definition

Amount of cumulative increase (decrease) in fair value of hedged liability in fair value hedge, attributable to hedged risk.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EE
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL109999712-113959

+ Details

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

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_OperatingExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_OtherIncomeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=wbs_MortgageBankingDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_OtherContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_LongTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Financial Instruments Impact of Fair Value on Qualifying Hedges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings		$ 10,008	$ 9,571
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)		44,164
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ (10,265)	1,833	5,555
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	10,471
Interest rate derivatives [Member] \| Operating Expense [Member] \| Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	10,369	11,068	8,477
Interest rate derivatives [Member] \| Operating Expense [Member] \| Not Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	411	8,206	4,241
Interest rate derivatives [Member] \| Other Income [Member] \| Not Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	(10,676)	(6,373)	1,314
Mortgage Banking Derivatives [Member] \| Operating Expense [Member] \| Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	(776)	636	(6)
Other Contract [Member] \| Operating Expense [Member] \| Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	878	(1,696)	$ 1,100
Long-term Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Liability, Fair Value Hedge	338,811	$ 344,164
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	$ 38,811