Summary of Significant Accounting Policies - Additional Information (Detail)			1 Months Ended	12 Months Ended
	Sep. 01, 2017 USD ($)	Jun. 13, 2016 USD ($)	May 31, 2015 $ / shares	Dec. 31, 2017 USD ($) Subsidiary secuirty $ / shares Office payment shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Mar. 31, 2015 $ / shares shares	Dec. 31, 2012 USD ($)
Accounting Policies [Line Items]
Number of office locations | Office				76
Number of unconsolidated subsidiary | Subsidiary				1
Common stock, shares authorized (in shares) | shares				65,000,000	65,000,000		65,000,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.01	$ 0.01	$ 0.01
Stock split conversion ratio			3
Number of securities are classified | secuirty				3
Minimum number of days principal or interest to be considered past due				90 days
Number of consecutive payments for borrower status to be normal, as per consistent repayment record | payment				6
Charges related to assets acquired through foreclosure				$ 300,000	$ 100,000	$ 300,000
Maturity of federal funds purchased				90 days
Settlement of realized tax position				50.00%
Reclassification due to the adoption of ASU No. 2018-02				$ 0
Write off of Deferred Debt Issuance Cost	$ 700,000			$ 695,000	0	$ 651,000
Scenario, Previously Reported
Accounting Policies [Line Items]
Common stock, shares authorized (in shares) | shares							20,000,000
Common stock, par value (in dollars per share) | $ / shares							$ 0.01
WSFS Financial Corporation
Accounting Policies [Line Items]
Number of wholly-owned subsidiaries | Subsidiary				3
Cypress
Accounting Policies [Line Items]
Assets under management				$ 901,500,000	738,500,000
West Capital
Accounting Policies [Line Items]
Assets under management				861,200,000	738,100,000
WSFS Capital Trust III
Accounting Policies [Line Items]
Amount of aggregate principal issued				67,000,000
Trust preferred securities redeemed				$ 51,500,000
Delaware
Accounting Policies [Line Items]
Number of office locations | Office				46
Pennsylvania
Accounting Policies [Line Items]
Number of office locations | Office				28
Virginia
Accounting Policies [Line Items]
Number of office locations | Office				1
Nevada
Accounting Policies [Line Items]
Number of office locations | Office				1
Senior unsecured fixed - to - floating rate notes
Accounting Policies [Line Items]
Debt instrument, face amount		$ 100,000,000
Interest rate on unsecured debt		4.50%
Redemption price, percentage		100.00%
LIBOR Rate | Senior unsecured fixed - to - floating rate notes
Accounting Policies [Line Items]
Variable interest rate		3.30%
6.25% Senior Notes Due 2019
Accounting Policies [Line Items]
Debt instrument, face amount								$ 55,000,000.0
Interest rate on unsecured debt	6.25%							6.25%
Write off of Deferred Debt Issuance Cost				$ 700,000
Accumulated Other Comprehensive (Loss) Income
Accounting Policies [Line Items]
Reclassification due to the adoption of ASU No. 2018-02				(1,660,000)
Retained Earnings
Accounting Policies [Line Items]
Reclassification due to the adoption of ASU No. 2018-02				$ 1,660,000
Computer Equipment
Accounting Policies [Line Items]
Useful life				3 years
Furniture and equipment
Accounting Policies [Line Items]
Useful life				5 years
Building Renovations
Accounting Policies [Line Items]
Useful life				10 years
Residential
Accounting Policies [Line Items]
Mortgage loans on real estate, foreclosures				$ 2,900,000	$ 3,700,000