CHANGE IN ACCUMULATED OTHER COMPREHENSIVE LOSS - Components of Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income taxes	$ (83,764)	$ (96,245)	$ (77,961)
Income before taxes	347,259	365,270	300,609
Reclassification out of Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to WSFS	14,926	16,609	10,822
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior service credits	(76)	(76)	(76)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Amortization of defined benefit pension plan-related items:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income taxes	60	83	35
Actuarial gains	(176)	(271)	(68)
Income before taxes	(252)	(347)	(144)
Net income attributable to WSFS	(192)	(264)	(109)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Net unrealized gains on terminated cash flow hedges:
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net unrealized losses to income during the period	0	(141)	(211)
Income taxes	0	34	51
Net income attributable to WSFS	0	(107)	(160)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Net unrealized holding losses on securities transferred between available-for-sale and held-to-maturity: | Net change in investment securities available for sale
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net unrealized losses to income during the period	19,892	22,343	14,593
Income taxes	(4,774)	(5,363)	(3,502)
Net income attributable to WSFS	$ 15,118	$ 16,980	$ 11,091