BUSINESS COMBINATIONS - Narrative (Details) $ / shares in Units, $ in Thousands		3 Months Ended
	Jan. 01, 2022 USD ($) $ / shares shares	Mar. 31, 2022 USD ($) bank	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
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]
Number of retail banking offices | bank		22
WSFS Bank
Business Acquisition [Line Items]
Number of retail banking offices | bank		12
Bryn Mawr Bank Corporation Acquisition
Business Acquisition [Line Items]
Percentage of outstanding common stock acquired	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	26,103	26,100
Loans not purchased with credit deterioration		23,500
Deferred income taxes	8,433
Intangible assets	74,565
Intangible assets acquired	$ 60,400
Bryn Mawr Bank Corporation Acquisition | Other assets
Business Acquisition [Line Items]
Property and equipment classified as held for sale.		$ 11,800
Bryn Mawr Bank Corporation Acquisition | Restricted Stock
Business Acquisition [Line Items]
Vested of restricted stock awards (in shares) | shares	226,643
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	$ 57,100
Bryn Mawr Bank Corporation Acquisition | Tradename
Business Acquisition [Line Items]
Intangible assets acquired	2,800
Bryn Mawr Bank Corporation Acquisition | Non-compete agreements
Business Acquisition [Line Items]
Intangible assets acquired	$ 500