STOCKHOLDERS' EQUITY AND REGULATORY CAPITAL - Narrative (Details)		3 Months Ended	12 Months Ended
	Jan. 01, 2022 USD ($)	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 $ / shares shares	Dec. 31, 2020 shares	Dec. 31, 2005 USD ($)
Capital Unit [Line Items]
Ratio of common equity Tier 1 capital to risk-weighted assets percentage		4.50%	4.50%	4.50%
Ratio of Tier 1 capital to risk-weighted assets percentage		0.1222	0.1222	0.1479
Ratio of total capital to risk-weighted assets percentage		0.1420	0.1420	0.1559
Tier 1 leverage ratio percentage		0.0979	0.0979	0.1024
Common stock outstanding, par value (in dollars per share) | $ / shares		$ 0.01	$ 0.01	$ 0.01
Coupon rate percentage		6.53%	6.53%
Cash that remains at the holding company		$ 205,800,000	$ 205,800,000
Minimum annual net income expected (as percent)		35.00%	35.00%
Junior Subordinated Debt
Capital Unit [Line Items]
Interest rate on unsecured debt percent		6.92%	6.92%
Treasury Stock
Capital Unit [Line Items]
Repurchases of common stock (in shares) | shares			4,151,117	267,309	3,950,855
Additional Stock Buyback Program
Capital Unit [Line Items]
Common stock average repurchase price (in dollars per share) | $ / shares			$ 46.78
WSFS Capital Trust III
Capital Unit [Line Items]
Pooled floating rate securities, par value						$ 2,000,000
Pooled floating rate securities issued						$ 67,000,000
Trusts
Capital Unit [Line Items]
Trust common securities owned	$ 774,000
Trusts | Junior Subordinated Debt
Capital Unit [Line Items]
Trust capital securities issued	11,700,000
Trust capital securities issued net	$ 23,400,000
LIBOR Rate
Capital Unit [Line Items]
Variable interest rate percentage		2.15%	2.15%
LIBOR Rate | WSFS Capital Trust III
Capital Unit [Line Items]
Variable interest rate percentage						1.77%
Trust preferred borrowings | LIBOR Rate | WSFS Capital Trust III
Capital Unit [Line Items]
Variable interest rate percentage						1.77%
Minimum
Capital Unit [Line Items]
Ratio of common equity Tier 1 capital to risk-weighted assets percentage		4.50%	4.50%
Ratio of Tier 1 capital to risk-weighted assets percentage		0.0600	0.0600
Ratio of total capital to risk-weighted assets percentage		0.0800	0.0800
Tier 1 leverage ratio percentage		0.0400	0.0400