Segment Information - Details of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Interest income	$ 137,350	$ 141,262	$ 142,903	$ 99,577	$ 77,794	$ 75,415	$ 72,151	$ 67,613	$ 521,092	$ 292,973	$ 254,726
Noninterest income	41,770	62,346	42,871	41,122	38,186	41,901	34,987	47,467	188,109	162,541	124,644
Total revenue									709,201	455,514	379,370
Interest expense	19,781	20,429	19,671	16,263	13,120	12,318	11,162	9,899	76,144	46,499	33,455
Noninterest expenses	98,126	109,561	107,848	97,592	61,350	52,454	57,831	53,412	413,127	225,047	226,461
Provision for loan and lease losses	1,590	4,121	12,195	7,654	3,306	3,716	2,498	3,650	25,560	13,170	10,964
Total expenses									514,831	284,716	270,880
Income before taxes	59,623	69,497	46,060	19,190	38,204	48,828	35,647	48,119	194,370	170,798	108,490
Income tax provision	14,199	15,902	10,091	6,260	8,486	9,893	6,907	10,769	46,452	36,055	58,246
Net income	45,424	53,595	35,969	12,930	29,718	38,935	28,740	37,350	147,918	134,743	50,244
Less: Net loss attributable to noncontrolling interest	(280)	(287)	(231)	(93)	0	0	0	0	(891)	0	0
Net income attributable to WSFS	$ 45,704	$ 53,882	$ 36,200	$ 13,023	$ 29,718	$ 38,935	$ 28,740	$ 37,350	148,809	134,743	50,244
Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									29,461	26,572	18,579
Noninterest income									11,446	9,712	8,607
Total revenue									40,907	36,284	27,186
Interest expense									29,461	26,572	18,579
Noninterest expenses									11,446	9,712	8,607
Total expenses									40,907	36,284	27,186
Operating Segments
Segment Reporting Information [Line Items]
Total revenue									750,108	491,798	406,556
Total expenses									555,738	321,000	298,066
Income before taxes									194,370	170,798	108,490
WSFS Bank
Segment Reporting Information [Line Items]
Interest income									510,492	282,846	245,932
Noninterest income									92,898	70,894	45,749
Total revenue									603,390	353,740	291,681
Interest expense									71,158	43,671	32,249
Noninterest expenses									348,351	172,254	158,942
Provision for loan and lease losses									24,884	12,934	10,527
Total expenses									444,393	228,859	201,718
WSFS Bank | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									12,380	14,722	9,567
Noninterest income									9,654	8,793	7,651
Total revenue									22,034	23,515	17,218
Interest expense									17,081	11,850	9,012
Noninterest expenses									1,792	919	956
Total expenses									18,873	12,769	9,968
WSFS Bank | Operating Segments
Segment Reporting Information [Line Items]
Total revenue									625,424	377,255	308,899
Total expenses									463,266	241,628	211,686
Income before taxes									162,158	135,627	97,213
Cash Connect
Segment Reporting Information [Line Items]
Interest income									0	0	0
Noninterest income									51,143	50,679	42,641
Total revenue									51,143	50,679	42,641
Interest expense									0	0	0
Noninterest expenses									35,377	32,378	26,654
Provision for loan and lease losses									0	0	0
Total expenses									35,377	32,378	26,654
Cash Connect | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									0	0	0
Noninterest income									890	774	810
Total revenue									890	774	810
Interest expense									7,808	10,417	6,812
Noninterest expenses									2,754	2,603	2,603
Total expenses									10,562	13,020	9,415
Cash Connect | Operating Segments
Segment Reporting Information [Line Items]
Total revenue									52,033	51,453	43,451
Total expenses									45,939	45,398	36,069
Income before taxes									6,094	6,055	7,382
Wealth Management
Segment Reporting Information [Line Items]
Interest income									10,600	10,127	8,794
Noninterest income									44,068	40,968	36,254
Total revenue									54,668	51,095	45,048
Interest expense									4,986	2,828	1,206
Noninterest expenses									29,399	20,415	40,865
Provision for loan and lease losses									676	236	437
Total expenses									35,061	23,479	42,508
Wealth Management | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									17,081	11,850	9,012
Noninterest income									902	145	146
Total revenue									17,983	11,995	9,158
Interest expense									4,572	4,305	2,755
Noninterest expenses									6,900	6,190	5,048
Total expenses									11,472	10,495	7,803
Wealth Management | Operating Segments
Segment Reporting Information [Line Items]
Total revenue									72,651	63,090	54,206
Total expenses									46,533	33,974	50,311
Income before taxes									$ 26,118	$ 29,116	$ 3,895