Segment Information - Details of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Interest income	$ 131,297	$ 123,370	$ 125,883	$ 133,855	$ 137,350	$ 141,262	$ 142,903	$ 99,577	$ 514,405	$ 521,092	$ 292,973
Noninterest income	46,632	49,171	64,375	40,847	41,770	62,346	42,871	41,122	201,025	188,109	162,541
Total revenue									715,430	709,201	455,514
Interest expense	8,296	10,322	12,127	17,705	19,781	20,429	19,671	16,263	48,450	76,144	46,499
Noninterest expenses	93,373	93,540	93,435	88,496	98,126	109,561	107,848	97,592	368,844	413,127	225,047
Provision for credit losses	(936)	2,716	94,754	56,646	1,590	4,121	12,195	7,654	153,180	25,560	13,170
Total expenses									570,474	514,831	284,716
Income before taxes	77,196	65,963	(10,058)	11,855	59,623	69,497	46,060	19,190	144,956	194,370	170,798
Income tax provision	17,455	15,140	(2,247)	1,288	14,199	15,902	10,091	6,260	31,636	46,452	36,055
Net income	59,741	50,823	(7,811)	10,567	45,424	53,595	35,969	12,930	113,320	147,918	134,743
Less: Net loss attributable to noncontrolling interest	(72)	(322)	(700)	(360)	(280)	(287)	(231)	(93)	(1,454)	(891)	0
Net income attributable to WSFS	$ 59,813	$ 51,145	$ (7,111)	$ 10,927	$ 45,704	$ 53,882	$ 36,200	$ 13,023	114,774	148,809	134,743
Capital expenditures									7,159	14,198	5,500
Operating Segments
Segment Reporting Information [Line Items]
Interest income									514,405	521,092	292,973
Noninterest income									201,025	188,109	162,541
Total revenue									747,663	750,108	491,798
Interest expense									48,450	76,144	46,499
Noninterest expenses									368,844	413,127	225,047
Total expenses									602,707	555,738	321,000
Income before taxes									144,956	194,370	170,798
Capital expenditures									7,159	14,198	5,498
Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									16,528	29,461	26,572
Noninterest income									15,705	11,446	9,712
Total revenue									32,233	40,907	36,284
Interest expense									16,528	29,461	26,572
Noninterest expenses									15,705	11,446	9,712
Total expenses									32,233	40,907	36,284
WSFS Bank
Segment Reporting Information [Line Items]
Total revenue									615,843	603,390	353,740
Provision for credit losses									149,453	24,884	12,934
Total expenses									506,680	444,393	228,859
WSFS Bank | Operating Segments
Segment Reporting Information [Line Items]
Interest income									505,258	510,492	282,846
Noninterest income									110,585	92,898	70,894
Total revenue									633,811	625,424	377,255
Interest expense									46,428	71,158	43,671
Noninterest expenses									310,799	348,351	172,254
Total expenses									520,945	463,266	241,628
Income before taxes									112,866	162,158	135,627
Capital expenditures									6,499	11,806	4,779
WSFS Bank | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									4,930	12,380	14,722
Noninterest income									13,038	9,654	8,793
Total revenue									17,968	22,034	23,515
Interest expense									11,598	17,081	11,850
Noninterest expenses									2,667	1,792	919
Total expenses									14,265	18,873	12,769
Cash Connect
Segment Reporting Information [Line Items]
Total revenue									40,899	51,143	50,679
Provision for credit losses									0	0	0
Total expenses									28,421	35,377	32,378
Cash Connect | Operating Segments
Segment Reporting Information [Line Items]
Interest income									0	0	0
Noninterest income									40,899	51,143	50,679
Total revenue									42,585	52,033	51,453
Interest expense									0	0	0
Noninterest expenses									28,421	35,377	32,378
Total expenses									33,341	45,939	45,398
Income before taxes									9,244	6,094	6,055
Capital expenditures									420	2,120	375
Cash Connect | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									851	0	0
Noninterest income									835	890	774
Total revenue									1,686	890	774
Interest expense									1,580	7,808	10,417
Noninterest expenses									3,340	2,754	2,603
Total expenses									4,920	10,562	13,020
Wealth Management
Segment Reporting Information [Line Items]
Total revenue									58,688	54,668	51,095
Provision for credit losses									3,727	676	236
Total expenses									35,373	35,061	23,479
Wealth Management | Operating Segments
Segment Reporting Information [Line Items]
Interest income									9,147	10,600	10,127
Noninterest income									49,541	44,068	40,968
Total revenue									71,267	72,651	63,090
Interest expense									2,022	4,986	2,828
Noninterest expenses									29,624	29,399	20,415
Total expenses									48,421	46,533	33,974
Income before taxes									22,846	26,118	29,116
Capital expenditures									240	272	344
Wealth Management | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									10,747	17,081	11,850
Noninterest income									1,832	902	145
Total revenue									12,579	17,983	11,995
Interest expense									3,350	4,572	4,305
Noninterest expenses									9,698	6,900	6,190
Total expenses									$ 13,048	$ 11,472	$ 10,495