SUBSEQUENT EVENTS (Details) - Subsequent Event $ in Millions	1 Months Ended
May 08, 2020 USD ($) Branch
Subsequent Event [Line Items]
Number of applications approved \| Branch	4,732
Loans approved for PPP	$ 971.2
COVID-19
Subsequent Event [Line Items]
Loans modified	$ 2,200.0

Amount, after troubled debt restructuring, of modified financing receivable.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsPostModificationRecordedInvestment2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Definition

Coronavirus Aid, Relief, and Economic Security (CARES) Act, Loans Approved

+ References

No definition available.

+ Details

Name:	wsfs_CoronavirusAidReliefAndEconomicSecurityCARESActLoansApproved
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Coronavirus Aid, Relief, and Economic Security (CARES) Act, Number Of Applications Approved

+ References

No definition available.

+ Details

Name:	wsfs_CoronavirusAidReliefAndEconomicSecurityCARESActNumberOfApplicationsApproved
Namespace Prefix:	wsfs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_UnusualOrInfrequentItemAxis=wsfs_COVID19Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: