SEGMENT INFORMATION - Segment Results (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Interest income	$ 75,415	$ 65,010	$ 215,179	$ 188,170
Noninterest income	41,901	32,441	124,355	92,209
Total revenue	117,316	97,451	339,534	280,379
Interest expense	12,318	8,881	33,379	24,624
Noninterest expenses	52,454	54,163	163,697	158,396
Provision for loan losses	3,716	2,896	9,864	6,901
Total expenses	68,488	65,940	206,940	189,921
Income before taxes	48,828	31,511	132,594	90,458
Income tax provision	9,893	10,942	27,569	30,382
Net income	38,935	20,569	105,025	60,076
Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	7,022	4,772	18,588	13,515
Noninterest income	2,358	1,971	7,137	6,515
Total revenue	9,380	6,743	25,725	20,030
Interest expense	7,022	4,772	18,588	13,515
Noninterest expenses	2,358	1,971	7,137	6,515
Total expenses	9,380	6,743	25,725	20,030
Operating Segments
Segment Reporting Information [Line Items]
Total revenue	126,696	104,194	365,259	300,409
Total expenses	77,868	72,683	232,665	209,951
Income before taxes	48,828	31,511	132,594	90,458
WSFS Bank
Segment Reporting Information [Line Items]
Interest income	72,836	62,748	207,725	181,670
Noninterest income	18,524	12,102	57,175	34,318
Total revenue	91,360	74,850	264,900	215,988
Interest expense	11,461	8,542	31,563	23,744
Noninterest expenses	44,922	39,546	126,862	117,288
Provision for loan losses	3,776	3,065	9,721	6,097
Total expenses	60,159	51,153	168,146	147,129
WSFS Bank | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	4,002	2,537	10,535	6,780
Noninterest income	2,122	1,721	6,449	5,791
Total revenue	6,124	4,258	16,984	12,571
Interest expense	3,020	2,235	8,053	6,735
Noninterest expenses	236	250	688	724
Total expenses	3,256	2,485	8,741	7,459
WSFS Bank | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	97,484	79,108	281,884	228,559
Total expenses	63,415	53,638	176,887	154,588
Income before taxes	34,069	25,470	104,997	73,971
Cash Connect
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Noninterest income	13,026	11,212	36,707	31,403
Total revenue	13,026	11,212	36,707	31,403
Interest expense	0	0	0	0
Noninterest expenses	8,133	7,048	23,357	19,774
Provision for loan losses	0	0	0	0
Total expenses	8,133	7,048	23,357	19,774
Cash Connect | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Noninterest income	200	213	581	611
Total revenue	200	213	581	611
Interest expense	2,885	1,856	7,460	4,843
Noninterest expenses	627	556	1,936	1,944
Total expenses	3,512	2,412	9,396	6,787
Cash Connect | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	13,226	11,425	37,288	32,014
Total expenses	11,645	9,460	32,753	26,561
Income before taxes	1,581	1,965	4,535	5,453
Wealth Management
Segment Reporting Information [Line Items]
Interest income	2,579	2,262	7,454	6,500
Noninterest income	10,351	9,127	30,473	26,488
Total revenue	12,930	11,389	37,927	32,988
Interest expense	857	339	1,816	880
Noninterest expenses	(601)	7,569	13,478	21,334
Provision for loan losses	(60)	(169)	143	804
Total expenses	196	7,739	15,437	23,018
Wealth Management | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	3,020	2,235	8,053	6,735
Noninterest income	36	37	107	113
Total revenue	3,056	2,272	8,160	6,848
Interest expense	1,117	681	3,075	1,937
Noninterest expenses	1,495	1,165	4,513	3,847
Total expenses	2,612	1,846	7,588	5,784
Wealth Management | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	15,986	13,661	46,087	39,836
Total expenses	2,808	9,585	23,025	28,802
Income before taxes	$ 13,178	$ 4,076	$ 23,062	$ 11,034