SEGMENT INFORMATION - Details of Segment Information - Statement of Financial Condition (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 580,299	$ 620,757	$ 711,372	$ 723,866
Goodwill	472,958	166,007
Other segment assets	11,219,416	6,462,106
Total assets	12,272,673	7,248,870
Capital expenditures	10,701	5,498
WSFS Bank
Segment Reporting Information [Line Items]
Cash and cash equivalents	255,440	115,147
Goodwill	452,759	145,808
Other segment assets	10,985,960	6,225,820
Total assets	11,694,159	6,486,775
Capital expenditures	9,160	4,779
Cash Connect
Segment Reporting Information [Line Items]
Cash and cash equivalents	313,964	491,863
Goodwill	0	0
Other segment assets	6,411	7,743
Total assets	320,375	499,606
Capital expenditures	1,411	375
Wealth Management
Segment Reporting Information [Line Items]
Cash and cash equivalents	10,895	13,747
Goodwill	20,199	20,199
Other segment assets	227,045	228,543
Total assets	258,139	262,489
Capital expenditures	$ 130	$ 344