SEGMENT INFORMATION - Segment Results (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Interest income	$ 72,151	$ 62,334	$ 139,764	$ 123,160
Noninterest income	34,987	31,676	82,454	59,768
Total revenue	107,138	94,010	222,218	182,928
Interest expense	11,162	8,020	21,061	15,743
Noninterest expenses	57,831	52,727	111,243	104,233
Provision for loan losses	2,498	1,843	6,148	4,005
Total expenses	71,491	62,590	138,452	123,981
Income before taxes	35,647	31,420	83,766	58,947
Income tax provision	6,907	10,850	17,676	19,440
Net income	28,740	20,570	66,090	39,507
Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	6,235	4,682	11,566	8,743
Noninterest income	2,456	2,153	4,779	4,544
Total revenue	8,691	6,835	16,345	13,287
Interest expense	6,235	4,682	11,566	8,743
Noninterest expenses	2,456	2,153	4,779	4,544
Total expenses	8,691	6,835	16,345	13,287
Operating Segments
Segment Reporting Information [Line Items]
Total revenue	115,829	100,845	238,563	196,215
Total expenses	80,182	69,425	154,797	137,268
Income before taxes	35,647	31,420	83,766	58,947
WSFS Bank
Segment Reporting Information [Line Items]
Interest income	69,599	60,234	134,889	118,922
Noninterest income	12,045	12,049	38,651	22,216
Total revenue	81,644	72,283	173,540	141,138
Interest expense	10,599	7,739	20,102	15,202
Noninterest expenses	42,505	38,782	81,940	77,742
Provision for loan losses	2,284	1,316	5,945	3,032
Total expenses	55,388	47,837	107,987	95,976
WSFS Bank | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	3,565	2,247	6,533	4,243
Noninterest income	2,219	1,906	4,327	4,070
Total revenue	5,784	4,153	10,860	8,313
Interest expense	2,670	2,435	5,033	4,500
Noninterest expenses	237	247	452	474
Total expenses	2,907	2,682	5,485	4,974
WSFS Bank | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	87,428	76,436	184,400	149,451
Total expenses	58,295	50,519	113,472	100,950
Income before taxes	29,133	25,917	70,928	48,501
Cash Connect
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Noninterest income	12,328	10,514	23,681	20,191
Total revenue	12,328	10,514	23,681	20,191
Interest expense	0	0	0	0
Noninterest expenses	7,905	6,591	15,224	12,726
Provision for loan losses	0	0	0	0
Total expenses	7,905	6,591	15,224	12,726
Cash Connect | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Noninterest income	200	207	381	398
Total revenue	200	207	381	398
Interest expense	2,516	1,582	4,575	2,987
Noninterest expenses	637	673	1,309	1,388
Total expenses	3,153	2,255	5,884	4,375
Cash Connect | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	12,528	10,721	24,062	20,589
Total expenses	11,058	8,846	21,108	17,101
Income before taxes	1,470	1,875	2,954	3,488
Wealth Management
Segment Reporting Information [Line Items]
Interest income	2,552	2,100	4,875	4,238
Noninterest income	10,614	9,113	20,122	17,361
Total revenue	13,166	11,213	24,997	21,599
Interest expense	563	281	959	541
Noninterest expenses	7,421	7,354	14,079	13,765
Provision for loan losses	214	527	203	973
Total expenses	8,198	8,162	15,241	15,279
Wealth Management | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	2,670	2,435	5,033	4,500
Noninterest income	37	40	71	76
Total revenue	2,707	2,475	5,104	4,576
Interest expense	1,049	665	1,958	1,256
Noninterest expenses	1,582	1,233	3,018	2,682
Total expenses	2,631	1,898	4,976	3,938
Wealth Management | Operating Segments
Segment Reporting Information [Line Items]
Total revenue	15,873	13,688	30,101	26,175
Total expenses	10,829	10,060	20,217	19,217
Income before taxes	$ 5,044	$ 3,628	$ 9,884	$ 6,958