Segment Information - Details of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Interest income	$ 65,010	$ 55,337	$ 188,170	$ 156,886
Noninterest income	32,441	27,586	92,209	76,762
Total revenue	97,451	82,923	280,379	233,648
Interest expense	8,881	6,316	24,624	16,095
Noninterest expenses	54,163	51,234	158,396	139,717
Provision for loan losses	2,896	5,828	6,901	7,862
Total expenses	65,940	63,378	189,921	163,674
Income before taxes	31,511	19,545	90,458	69,974
Income tax provision	10,942	6,823	30,382	24,004
Net income	20,569	12,722	60,076	45,970
Capital expenditures	2,840	11,159	7,194	15,037
Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	4,772	3,000	13,515	8,743
Noninterest income	1,971	2,396	6,515	6,919
Total revenue	6,743	5,396	20,030	15,662
Interest expense	4,772	3,000	13,515	8,743
Noninterest expenses	1,971	2,396	6,515	6,919
Total expenses	6,743	5,396	20,030	15,662
External Customer
Segment Reporting Information [Line Items]
Total revenue	104,194	88,319	300,409	249,310
Total expenses	72,683	68,774	209,951	179,336
WSFS Bank
Segment Reporting Information [Line Items]
Interest income	62,748	53,332	181,670	150,862
Noninterest income	12,102	11,957	34,318	31,982
Total revenue	74,850	65,289	215,988	182,844
Interest expense	8,542	6,113	23,744	15,506
Noninterest expenses	39,546	40,991	117,288	109,265
Provision for loan losses	3,065	5,669	6,097	7,675
Total expenses	51,153	52,773	147,129	132,446
Income before taxes	25,470	14,004	73,971	54,154
Capital expenditures	2,688	10,900	6,611	14,346
WSFS Bank | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	2,537	1,302	6,780	3,498
Noninterest income	1,721	2,140	5,791	6,211
Total revenue	4,258	3,442	12,571	9,709
Interest expense	2,235	1,698	6,735	5,245
Noninterest expenses	250	256	724	708
Total expenses	2,485	1,954	7,459	5,953
WSFS Bank | External Customer
Segment Reporting Information [Line Items]
Total revenue	79,108	68,731	228,559	192,553
Total expenses	53,638	54,727	154,588	138,399
Cash Connect
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Noninterest income	11,212	9,369	31,403	26,437
Total revenue	11,212	9,369	31,403	26,437
Interest expense	0	0	0	0
Noninterest expenses	7,048	5,743	19,774	16,681
Provision for loan losses	0	0	0	0
Total expenses	7,048	5,743	19,774	16,681
Income before taxes	1,965	2,321	5,453	6,229
Capital expenditures	35	248	103	672
Cash Connect | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Noninterest income	213	229	611	632
Total revenue	213	229	611	632
Interest expense	1,856	790	4,843	1,973
Noninterest expenses	556	744	1,944	2,186
Total expenses	2,412	1,534	6,787	4,159
Cash Connect | External Customer
Segment Reporting Information [Line Items]
Total revenue	11,425	9,598	32,014	27,069
Total expenses	9,460	7,277	26,561	20,840
Wealth Management
Segment Reporting Information [Line Items]
Interest income	2,262	2,005	6,500	6,024
Noninterest income	9,127	6,260	26,488	18,343
Total revenue	11,389	8,265	32,988	24,367
Interest expense	339	203	880	589
Noninterest expenses	7,569	4,500	21,334	13,771
Provision for loan losses	(169)	159	804	187
Total expenses	7,739	4,862	23,018	14,547
Income before taxes	4,076	3,220	11,034	9,591
Capital expenditures	117	11	480	19
Wealth Management | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income	2,235	1,698	6,735	5,245
Noninterest income	37	27	113	76
Total revenue	2,272	1,725	6,848	5,321
Interest expense	681	512	1,937	1,525
Noninterest expenses	1,165	1,396	3,847	4,025
Total expenses	1,846	1,908	5,784	5,550
Wealth Management | External Customer
Segment Reporting Information [Line Items]
Total revenue	13,661	9,990	39,836	29,688
Total expenses	$ 9,585	$ 6,770	$ 28,802	$ 20,097