Parent Company Financial Information - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Net income attributable to WSFS	$ 59,813	$ 51,145	$ (7,111)	$ 10,927	$ 45,704	$ 53,882	$ 36,200	$ 13,023	$ 114,774	$ 148,809	$ 134,743
Adjustments to reconcile net income to net cash provided by operating activities:
Unrealized losses (gains) on equity investments									(761)	(26,175)	(20,745)
(Increase) decrease in other assets									(18,339)	(4,676)	(6,297)
Increase (decrease) in other liabilities									24,675	30,922	(2,931)
Net cash provided by operating activities									15,142	89,866	135,574
Investing activities:
Sale of Visa Class B shares									0	0	6,186
Purchases of Visa Class B shares									0	0	(1,568)
Net cash (used in) provided by investing activities									(874,944)	293,823	(359,910)
Financing activities:
Issuance of common stock and exercise of common stock options									2,032	7,755	11,253
Issuance of senior debt, net of costs									147,780	0	0
Purchase of treasury stock									(155,832)	(97,186)	(31,202)
Dividends paid									(24,369)	(22,463)	(13,249)
Net cash provided by (used in) financing activities									1,942,785	(432,694)	121,227
Increase (decrease) in cash, cash equivalents, and restricted cash									1,082,983	(49,005)	(103,109)
Cash, cash equivalents, and restricted cash at beginning of period				571,752				620,757	571,752	620,757	723,866
Cash, cash equivalents, and restricted cash at end of period	1,654,735				571,752				1,654,735	571,752	620,757
WSFS Financial Corporation
Operating activities:
Net income attributable to WSFS									114,774	148,809	134,743
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed loss (income) of subsidiaries									84,346	92,020	(97,626)
Realized gains on sale of equity investments									0	0	(3,757)
Unrealized losses (gains) on equity investments									1,617	(3,646)	(15,088)
(Increase) decrease in other assets									(4,537)	3,538	2,265
Increase (decrease) in other liabilities									7,684	6,012	(237)
Net cash provided by operating activities									203,884	246,733	20,300
Investing activities:
Sale of Visa Class B shares									0	0	6,186
Net cash for business combinations									0	(93,990)	0
Purchases of Visa Class B shares									0	0	(51)
Net cash (used in) provided by investing activities									0	(93,990)	6,135
Financing activities:
Issuance of common stock and exercise of common stock options									2,032	7,755	11,253
Issuance of senior debt, net of costs									147,780	0	0
Purchase of treasury stock									(155,832)	(97,186)	(31,202)
Dividends paid									(24,369)	(22,463)	(13,249)
Net cash provided by (used in) financing activities									(30,389)	(111,894)	(33,198)
Increase (decrease) in cash, cash equivalents, and restricted cash									173,495	40,849	(6,763)
Cash, cash equivalents, and restricted cash at beginning of period				$ 71,430				$ 30,581	71,430	30,581	37,344
Cash, cash equivalents, and restricted cash at end of period	$ 244,925				$ 71,430				$ 244,925	$ 71,430	$ 30,581