Borrowed Funds - Additional Information (Detail) - USD ($)			12 Months Ended
	Sep. 01, 2017	Jun. 13, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2005	Dec. 31, 2012
Repurchase Agreement Counterparty [Line Items]
FHLB stock			$ 31,284,000	$ 38,248,000
Purchase of federal funds			$ 28,000,000	$ 130,000,000
Federal funds rate on securities purchased			1.54%	0.79%
Senior unsecured notes, amount		$ 100,000,000
Write off of Deferred Debt Issuance Cost	$ 700,000		$ 695,000	$ 0	$ 651,000
Aggregate principal amount	$ 55,000,000		98,171,000	152,050,000
Collateralized borrowings			$ 34,600,000	$ 64,100,000
Average rates on borrowings			0.09%	0.09%
6.25% Senior Notes Due 2019
Repurchase Agreement Counterparty [Line Items]
Interest rate on unsecured debt	6.25%						6.25%
Write off of Deferred Debt Issuance Cost			$ 700,000
4.50% Senior Unsecured Notes Mature on 2026
Repurchase Agreement Counterparty [Line Items]
Interest rate on unsecured debt		4.50%
Senior unsecured notes, percentage of principle amount to be redeemed		100.00%
LIBOR Rate | 4.50% Senior Unsecured Notes Mature on 2026
Repurchase Agreement Counterparty [Line Items]
Variable interest rate			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 | Trust preferred borrowings
Repurchase Agreement Counterparty [Line Items]
Variable interest rate						1.77%
Federal Home Loan Bank
Repurchase Agreement Counterparty [Line Items]
Percentage of member asset value			0.10%
Percentage of advances outstanding			4.00%
FHLB stock			$ 31,300,000	$ 38,200,000
Dividends from the FHLB			$ 1,600,000	1,600,000
Minimum
Repurchase Agreement Counterparty [Line Items]
Interest rates on advances from FHLB			0.93606%
Maximum
Repurchase Agreement Counterparty [Line Items]
Interest rates on advances from FHLB			1.73097%
Federal Reserve Bank of Philadelphia
Repurchase Agreement Counterparty [Line Items]
Loans pledged as collateral			$ 222,800,000	$ 275,100,000
Borrowed funds			$ 0
Trust preferred borrowings | WSFS Capital Trust III | LIBOR Rate
Repurchase Agreement Counterparty [Line Items]
Variable interest rate			1.77%