Segment Information - Details of Segment Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Interest income	$ 42,851,000	$ 37,785,000
Noninterest income	21,095,000	18,364,000
Total revenue	63,946,000	56,149,000
Interest expense	4,034,000	3,741,000
Noninterest expenses	38,913,000	33,884,000
Provision for loan loss	786,000	2,630,000
Total expenses	43,733,000	40,255,000
Income before taxes	20,213,000	15,894,000
Income tax provision (benefit)	7,324,000	(1,017,000)
Net Income	12,889,000	16,911,000
Cash and cash equivalents	505,638,000		508,039,000
Goodwill	48,824,000		48,651,000
Other segment assets	4,392,018,000		4,296,630,000
Total assets	4,946,480,000		4,853,320,000
Capital expenditures	817,000		537,000
Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Interest income	2,318,000	2,252,000
Noninterest income	1,970,000	1,957,000
Total revenue	4,288,000	4,209,000
Interest expense	2,318,000	2,252,000
Noninterest expenses	1,970,000	1,957,000
Total expenses	4,288,000	4,209,000
External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	68,234,000	60,358,000
Total expenses	48,021,000	44,464,000
WSFS Bank [Member]
Segment Reporting Information [Line Items]
Interest income	40,823,000	35,921,000
Noninterest income	9,189,000	8,395,000
Total revenue	50,012,000	44,316,000
Interest expense	3,912,000	3,630,000
Noninterest expenses	31,079,000	27,318,000
Provision for loan loss	733,000	2,323,000
Total expenses	35,724,000	33,271,000
Income before taxes	15,310,000	11,974,000
Cash and cash equivalents	66,854,000		73,395,000
Goodwill	43,690,000		43,517,000
Other segment assets	3,824,272,000		4,107,212,000
Total assets	3,934,816,000		4,224,124,000
Capital expenditures	817,000		478,000
WSFS Bank [Member] | Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Interest income	871,000	831,000
Noninterest income	1,784,000	1,738,000
Total revenue	2,655,000	2,569,000
Interest expense	1,447,000	1,421,000
Noninterest expenses	186,000	219,000
Total expenses	1,633,000	1,640,000
WSFS Bank [Member] | External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	52,667,000	46,885,000
Total expenses	37,357,000	34,911,000
Cash Connect [Member]
Segment Reporting Information [Line Items]
Noninterest income	6,639,000	6,014,000
Total revenue	6,639,000	6,014,000
Noninterest expenses	4,175,000	3,550,000
Total expenses	4,175,000	3,550,000
Income before taxes	1,645,000	1,740,000
Cash and cash equivalents	430,888,000		431,527,000
Other segment assets	3,002,000		2,006,000
Total assets	433,890,000		433,533,000
Capital expenditures			56,000
Cash Connect [Member] | Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Noninterest income	168,000	193,000
Total revenue	168,000	193,000
Interest expense	373,000	331,000
Noninterest expenses	614,000	586,000
Total expenses	987,000	917,000
Cash Connect [Member] | External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	6,807,000	6,207,000
Total expenses	5,162,000	4,467,000
Trust & Wealth Management [Member]
Segment Reporting Information [Line Items]
Interest income	2,028,000	1,864,000
Noninterest income	5,267,000	3,955,000
Total revenue	7,295,000	5,819,000
Interest expense	122,000	111,000
Noninterest expenses	3,659,000	3,016,000
Provision for loan loss	53,000	307,000
Total expenses	3,834,000	3,434,000
Income before taxes	3,258,000	2,180,000
Cash and cash equivalents	7,896,000		3,117,000
Goodwill	5,134,000		5,134,000
Other segment assets	564,744,000		187,412,000
Total assets	577,774,000		195,663,000
Capital expenditures			3,000
Trust & Wealth Management [Member] | Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Interest income	1,447,000	1,421,000
Noninterest income	18,000	26,000
Total revenue	1,465,000	1,447,000
Interest expense	498,000	500,000
Noninterest expenses	1,170,000	1,152,000
Total expenses	1,668,000	1,652,000
Trust & Wealth Management [Member] | External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	8,760,000	7,266,000
Total expenses	$ 5,502,000	$ 5,086,000