Quarterly Financial Summary (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Information Disclosure [Abstract]
Interest income	$ 137,350	$ 141,262	$ 142,903	$ 99,577	$ 77,794	$ 75,415	$ 72,151	$ 67,613	$ 521,092	$ 292,973	$ 254,726
Interest expense	19,781	20,429	19,671	16,263	13,120	12,318	11,162	9,899	76,144	46,499	33,455
Net interest income	117,569	120,833	123,232	83,314	64,674	63,097	60,989	57,714	444,948	246,474	221,271
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
Net interest income after provision for loan and lease losses	115,979	116,712	111,037	75,660	61,368	59,381	58,491	54,064	419,388	233,304	210,307
Noninterest income	41,770	62,346	42,871	41,122	38,186	41,901	34,987	47,467	188,109	162,541	124,644
Noninterest expenses	98,126	109,561	107,848	97,592	61,350	52,454	57,831	53,412	413,127	225,047	226,461
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
Earnings Per Share [Abstract]
Basic (in dollars per share)	$ 0.88	$ 1.02	$ 0.68	$ 0.34	$ 0.94	$ 1.22	$ 0.91	$ 1.19	$ 3.02	$ 4.27	$ 1.60
Diluted (in dollars per share)	$ 0.88	$ 1.02	$ 0.68	$ 0.33	$ 0.93	$ 1.20	$ 0.89	$ 1.16	$ 3.00	$ 4.19	$ 1.56