Borrowed Funds - Additional Information (Detail) - USD ($)			12 Months Ended
	Sep. 01, 2017	Jun. 13, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2005	Dec. 31, 2012
Repurchase Agreement Counterparty [Line Items]
FHLB stock			$ 19,259,000	$ 31,284,000
Purchase of federal funds			$ 158,000,000	$ 28,000,000
Federal funds rate on securities purchased (as percent)			2.52%	1.54%
Securities sold under agreements to repurchase			$ 0	$ 0
Senior debt	$ 55,000,000		98,388,000	98,171,000
Write-off of unamortized debt issuance costs	$ 700,000		0	695,000	$ 0
Senior unsecured notes, amount		$ 100,000,000
Collateralized borrowings			$ 47,900,000	$ 34,600,000
Average rates on borrowings (as percent)			0.12%	0.09%
Federal Reserve Bank of Philadelphia
Repurchase Agreement Counterparty [Line Items]
Loans pledged as collateral			$ 176,400,000	$ 222,800,000
Borrowed funds			0	0
6.25% Senior Notes Due 2019
Repurchase Agreement Counterparty [Line Items]
Interest rate on unsecured debt (as percent)	6.25%						6.25%
Write-off of unamortized debt issuance costs			$ 700,000
4.50% Senior Unsecured Notes Mature on 2026
Repurchase Agreement Counterparty [Line Items]
Interest rate on unsecured debt (as percent)		4.50%
Senior unsecured notes, percentage of principle amount to be redeemed (as percent)		100.00%
4.50% Senior Unsecured Notes Mature on 2026 | LIBOR Rate
Repurchase Agreement Counterparty [Line Items]
Variable interest rate (as percent)		3.30%
WSFS Capital Trust III
Repurchase Agreement Counterparty [Line Items]
Aggregate principal amount of Pooled Floating Rate Securities						$ 67,000,000
WSFS Capital Trust III | LIBOR Rate
Repurchase Agreement Counterparty [Line Items]
Variable interest rate (as percent)						1.77%
Federal Home Loan Bank
Repurchase Agreement Counterparty [Line Items]
Percentage of member asset value (as percent)			0.10%
Percentage of advances outstanding (as percent)			4.00%
FHLB stock			$ 19,300,000	31,300,000
Dividends from the FHLB			$ 1,500,000	$ 1,600,000
Minimum
Repurchase Agreement Counterparty [Line Items]
Interest rates on advances from FHLB (as percent)			1.50%
Maximum
Repurchase Agreement Counterparty [Line Items]
Interest rates on advances from FHLB (as percent)			2.79%