Segment Information - Details of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Interest income	$ 77,794	$ 75,415	$ 72,151	$ 67,613	$ 66,556	$ 65,010	$ 62,334	$ 60,826	$ 292,973	$ 254,726	$ 216,578
Noninterest income	38,186	41,901	34,987	47,467	32,435	32,441	31,676	28,092	162,541	124,644	105,061
Total revenue									455,514	379,370	321,639
Interest expense	13,120	12,318	11,162	9,899	8,831	8,881	8,020	7,723	46,499	33,455	22,833
Noninterest expenses	61,350	52,454	57,831	53,412	68,065	54,163	52,727	51,506	225,047	226,461	188,666
Provision for loan losses	3,306	3,716	2,498	3,650	4,063	2,896	1,843	2,162	13,170	10,964	12,986
Total expenses									284,716	270,880	224,485
Income before taxes	38,204	48,828	35,647	48,119	18,032	31,511	31,420	27,527	170,798	108,490	97,154
Income tax provision									36,055	58,246	33,074
Net income	$ 29,718	$ 38,935	$ 28,740	$ 37,350	$ (9,832)	$ 20,569	$ 20,570	$ 18,937	134,743	50,244	64,080
Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									26,572	18,579	12,113
Noninterest income									9,712	8,607	9,098
Total revenue									36,284	27,186	21,211
Interest expense									26,572	18,579	12,113
Noninterest expenses									9,712	8,607	9,098
Total expenses									36,284	27,186	21,211
Operating Segments
Segment Reporting Information [Line Items]
Total revenue									491,798	406,556	342,850
Total expenses									321,000	298,066	245,696
Income before taxes									170,798	108,490	97,154
WSFS Bank
Segment Reporting Information [Line Items]
Interest income									282,846	245,932	208,525
Noninterest income									70,894	45,749	42,565
Total revenue									353,740	291,681	251,090
Interest expense									43,671	32,249	22,028
Noninterest expenses									172,254	158,942	146,526
Provision for loan losses									12,934	10,527	9,370
Total expenses									228,859	201,718	177,924
WSFS Bank | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									14,722	9,567	4,963
Noninterest income									8,793	7,651	8,145
Total revenue									23,515	17,218	13,108
Interest expense									11,850	9,012	7,150
Noninterest expenses									919	956	953
Total expenses									12,769	9,968	8,103
WSFS Bank | Operating Segments
Segment Reporting Information [Line Items]
Total revenue									377,255	308,899	264,198
Total expenses									241,628	211,686	186,027
Income before taxes									135,627	97,213	78,171
Cash Connect
Segment Reporting Information [Line Items]
Interest income									0	0	0
Noninterest income									50,679	42,641	35,776
Total revenue									50,679	42,641	35,776
Interest expense									0	0	0
Noninterest expenses									32,378	26,654	22,442
Provision for loan losses									0	0	0
Total expenses									32,378	26,654	22,442
Cash Connect | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									0	0	0
Noninterest income									774	810	835
Total revenue									774	810	835
Interest expense									10,417	6,812	2,915
Noninterest expenses									2,603	2,603	2,799
Total expenses									13,020	9,415	5,714
Cash Connect | Operating Segments
Segment Reporting Information [Line Items]
Total revenue									51,453	43,451	36,611
Total expenses									45,398	36,069	28,156
Income before taxes									6,055	7,382	8,455
Wealth Management
Segment Reporting Information [Line Items]
Interest income									10,127	8,794	8,053
Noninterest income									40,968	36,254	26,720
Total revenue									51,095	45,048	34,773
Interest expense									2,828	1,206	805
Noninterest expenses									20,415	40,865	19,698
Provision for loan losses									236	437	3,616
Total expenses									23,479	42,508	24,119
Wealth Management | Inter-Segment Eliminations
Segment Reporting Information [Line Items]
Interest income									11,850	9,012	7,150
Noninterest income									145	146	118
Total revenue									11,995	9,158	7,268
Interest expense									4,305	2,755	2,048
Noninterest expenses									6,190	5,048	5,346
Total expenses									10,495	7,803	7,394
Wealth Management | Operating Segments
Segment Reporting Information [Line Items]
Total revenue									63,090	54,206	42,041
Total expenses									33,974	50,311	31,513
Income before taxes									$ 29,116	$ 3,895	$ 10,528