BUSINESS COMBINATIONS - Narrative (Details) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended
	Jan. 01, 2022 USD ($) $ / shares shares	Mar. 31, 2022 bank	Jun. 30, 2022 USD ($)	Dec. 31, 2021 $ / shares
Business Acquisition [Line Items]
Each share of BMBC common stock was exchanged for shares of WSFS common stock (in dollars per share) | $ / shares	$ 0.90
PCD loans allowance for credit losses at acquisition			$ 26,103
Bryn Mawr Bank Corporation Acquisition
Business Acquisition [Line Items]
Number of retail banking offices | bank		22
WSFS Bank
Business Acquisition [Line Items]
Number of retail banking offices | bank		12
Trust preferred borrowings
Business Acquisition [Line Items]
Debt discount			2,500
Subordinated Debt
Business Acquisition [Line Items]
Debt premium			700
Bryn Mawr Bank Corporation Acquisition
Business Acquisition [Line Items]
Percentage of outstanding common stock acquired (in percent)	100.00%
Total consideration	$ 908,032
Number of common stock acquired (in shares) | shares	19,903,230
Share price (in dollars per share) | $ / shares				$ 50.12
Remeasurement period	1 year
Investment securities	$ 500,400
Loans and leases	3,456,748
Initial allowance on acquired PCD loans			49,600
PCD loans allowance for credit losses at acquisition			26,100
Loans purchased with no credit deterioration			23,500
Deferred income taxes	6,322
Intangible assets	73,065
Intangible assets acquired	56,100
Bryn Mawr Bank Corporation Acquisition | Other assets
Business Acquisition [Line Items]
Property and equipment classified as held for sale.			$ 13,100
Bryn Mawr Bank Corporation Acquisition | Core deposits
Business Acquisition [Line Items]
Intangible assets	$ 10,900
Useful life	10 years
Bryn Mawr Bank Corporation Acquisition | Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired	$ 53,000
Bryn Mawr Bank Corporation Acquisition | Tradename
Business Acquisition [Line Items]
Intangible assets acquired	2,900
Bryn Mawr Bank Corporation Acquisition | Non-compete agreements
Business Acquisition [Line Items]
Intangible assets acquired	$ 200
Bryn Mawr Bank Corporation Acquisition | Restricted Stock
Business Acquisition [Line Items]
Vested of restricted stock awards (in shares) | shares	226,643