Parent Company Financial Information - Condensed Statements of Cash Flows (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
Operating activities:
Net Income	$ 29,718	$ 38,935	$ 28,740	$ 37,350	$ (9,832)	$ 20,569	$ 20,570	$ 18,937	$ 134,743	$ 50,244	$ 64,080
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of equity investments, net									(3,757)	0	0
Unrealized gains on equity investments									(20,745)	0	0
(Decrease) increase in other assets									(6,297)	(2,517)	443
(Decrease) increase in other liabilities									(2,931)	7,353	3,709
Net cash provided by operating activities									135,574	130,168	80,180
Investing activities:
Sale of Visa Class B shares									6,186	0	0
Purchases of Visa Class B shares									(1,568)	(10,072)	(387)
Net cash used for investing activities									(359,910)	(388,786)	(276,593)
Financing activities:
Repayment of long-term debt									0	0	(10,000)
Issuance of common stock									11,253	3,421	1,900
Repayment of senior debt									0	(55,000)	0
Issuance of senior debt									0	0	97,849
Buy back of common stock									(31,202)	(11,752)	(14,312)
Cash dividends paid									(13,249)	(9,425)	(7,632)
Net cash provided by financing activities									121,227	160,561	457,157
(Decrease) increase in cash and cash equivalents									(103,109)	(98,057)	260,744
Cash and cash equivalents at beginning of year				723,866				821,923	723,866	821,923	561,179
Cash and cash equivalents at end of year	620,757				723,866				620,757	723,866	821,923
WSFS Financial Corporation
Operating activities:
Net Income									134,743	50,244	64,080
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed (income) loss of subsidiaries									(97,626)	(35,722)	779
Gain on sale of equity investments, net									(3,757)	0	0
Unrealized gains on equity investments									(15,088)	0	0
(Decrease) increase in other assets									2,265	1,618	133
(Decrease) increase in other liabilities									(237)	1,422	655
Net cash provided by operating activities									20,300	17,562	65,647
Investing activities:
Payments for investment in and advances to subsidiaries									0	(1,360)	(119)
Sale or repayment of investments in and advances to subsidiaries									0	1,066	1,220
Sale of Visa Class B shares									6,186	0	0
Net cash from business combinations									0	0	(57,604)
Purchases of Visa Class B shares									(51)	(10,072)	(387)
Net cash used for investing activities									6,135	(10,366)	(56,890)
Financing activities:
Repayment of long-term debt									0	0	(10,000)
Issuance of common stock									11,253	3,307	1,900
Repayment of senior debt									0	(55,000)	0
Issuance of senior debt									0	0	97,849
Buy back of common stock									(31,202)	(11,752)	(14,312)
Cash dividends paid									(13,249)	(9,425)	(7,632)
Net cash provided by financing activities									(33,198)	(72,870)	67,805
(Decrease) increase in cash and cash equivalents									(6,763)	(65,674)	76,562
Cash and cash equivalents at beginning of year				$ 37,344				$ 103,018	37,344	103,018	26,456
Cash and cash equivalents at end of year	$ 30,581				$ 37,344				$ 30,581	$ 37,344	$ 103,018