Reverse Mortgage Loans - Summary of Estimated Cash Payments to Reverse Mortgagors (Detail) $ in Thousands	Sep. 30, 2015 USD ($)
Mortgage Banking [Abstract]
Remaining in 2015	$ 152
2016	538
2017	429
2018	338
2019	264
Years 2020 - 2024	624
Years 2025 - 2029	131
Years 2030 - 2034	21
Thereafter	2
Total	$ 2,499

No definition available.

Name:	us-gaap_MortgageBankingAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmount
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Remainder Of Fiscal Year

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountRemainderOfFiscalYear
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Eleven To Fifteen

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearElevenToFifteen
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Five

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearFive
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Four

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearFour
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Six To Ten

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearSixToTen
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Sixteen To Twenty

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearSixteenToTwenty
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Thereafter

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearThereafter
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Three

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearThree
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash Payments To Reverse Mortgagors Estimated Amount Year Two

+ References

No definition available.

+ Details

Name:	wsfs_CashPaymentsToReverseMortgagorsEstimatedAmountYearTwo
Namespace Prefix:	wsfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant