Parent Company Financial Information - Condensed Statements of Income (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
Income:
Unrealized gains on equity investments									$ 333	$ 21	$ 1,984
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
Expense:
Interest expense	19,781	20,429	19,671	16,263	13,120	12,318	11,162	9,899	76,144	46,499	33,455
Other operating expense	(137,350)	(141,262)	(142,903)	(99,577)	(77,794)	(75,415)	(72,151)	(67,613)	(521,092)	(292,973)	(254,726)
Net expenses	(117,569)	(120,833)	(123,232)	(83,314)	(64,674)	(63,097)	(60,989)	(57,714)	(444,948)	(246,474)	(221,271)
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
WSFS Financial Corporation
Income:
Interest income									5,589	1,591	3,167
Unrealized gains on equity investments									3,646	15,819	0
Noninterest income									240,408	28,038	20,528
Total revenue									249,643	45,448	23,695
Expense:
Interest expense									7,490	7,290	9,168
Other operating expense									259	245	996
Net expenses									7,749	7,535	10,164
Income before equity in undistributed income of subsidiaries									241,894	37,913	13,531
Equity in undistributed (loss) income of subsidiaries									(92,020)	97,626	35,722
Income before taxes									149,874	135,539	49,253
Income tax provision									1,065	796	(991)
Net income attributable to WSFS									$ 148,809	$ 134,743	$ 50,244