BUSINESS COMBINATIONS - Narrative (Details) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Jan. 01, 2022 USD ($) $ / shares shares	Mar. 31, 2022 bank	Dec. 31, 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
Initial allowance on acquired PCD loans			$ 26,103
BMBC
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
BMBC
Business Acquisition [Line Items]
Percentage of outstanding common stock acquired (in percent)	100.00%
Value of 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
Fair values as of the acquisition date	3,500,000
Initial allowance on acquired PCD loans			49,600
Initial allowance on acquired PCD loans			26,100
Loans purchased with no credit deterioration			23,500
Deferred income taxes	6,563
Intangible assets	73,065
Intangible assets acquired	56,100
BMBC | Other assets
Business Acquisition [Line Items]
Property and equipment classified as held for sale.			$ 7,500
BMBC | Core deposits
Business Acquisition [Line Items]
Intangible assets	$ 10,900
Useful life	10 years
BMBC | Customer relationships
Business Acquisition [Line Items]
Intangible assets acquired	$ 53,000
BMBC | Trade Names
Business Acquisition [Line Items]
Intangible assets acquired	2,900
BMBC | Non-compete agreements
Business Acquisition [Line Items]
Intangible assets acquired	$ 200
BMBC | Restricted Stock
Business Acquisition [Line Items]
Vested of restricted stock awards (in shares) | shares	226,643