Allowance for Loan Losses and Credit Quality Information - Summary of Nonaccrual and Past Due Loans (Parenthetical) (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Receivables [Abstract]
Acquired non-impaired loans	$ 354,694	$ 371,100	$ 141,716

Loans and leases receivable acquired non impaired loans.

No definition available.

Name:	wsfs_LoansAndLeasesReceivableAcquiredNonImpairedLoans
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant