Parent Company Financial Information - Condensed Statements of Income (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
Income:
Unrealized gains on equity investments									$ 21	$ 1,984	$ 2,369
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
Expenses:
Interest expense	13,120	12,318	11,162	9,899	8,831	8,881	8,020	7,723	46,499	33,455	22,833
Other operating expenses	(77,794)	(75,415)	(72,151)	(67,613)	(66,556)	(65,010)	(62,334)	(60,826)	(292,973)	(254,726)	(216,578)
Net expenses	(64,674)	(63,097)	(60,989)	(57,714)	(57,725)	(56,129)	(54,314)	(53,103)	(246,474)	(221,271)	(193,745)
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	$ 8,486	$ 9,893	$ 6,907	$ 10,769	$ 27,864	$ 10,942	$ 10,850	$ 8,590	36,055	58,246	33,074
WSFS Financial Corporation
Income:
Interest income									1,591	3,167	3,402
Unrealized gains on equity investments									15,819	0	0
Noninterest income									28,038	20,528	68,498
Total revenue									45,448	23,695	71,900
Expenses:
Interest expense									7,290	9,168	7,979
Other operating expenses									245	996	747
Net expenses									7,535	10,164	8,726
Income before equity in undistributed income of subsidiaries									37,913	13,531	63,174
Equity in undistributed income (loss) of subsidiaries									97,626	35,722	(779)
Income before taxes									135,539	49,253	62,395
Income tax provision									796	(991)	(1,685)
Net income allocable to common stockholders									$ 134,743	$ 50,244	$ 64,080