Segment Information - Details of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Interest income	$ 44,857	$ 40,799	$ 130,763	$ 117,997
Noninterest income	21,665	20,304	65,218	58,291
Total revenue	66,522	61,103	195,981	176,288
Interest expense	3,860	4,052	11,859	11,729
Noninterest expenses	38,705	39,163	116,272	108,272
Provision for loan losses	1,453	333	6,012	3,013
Total expenses	44,018	43,548	134,143	123,014
Income before taxes	22,504	17,555	61,838	53,274
Income tax provision	8,078	6,142	22,289	12,225
Net Income	14,426	11,413	39,549	41,049
Capital expenditures	4,969	981	8,668	2,366
Cash and cash equivalents	529,037	471,301	529,037	471,301	$ 508,039	$ 484,426
Goodwill	48,787		48,787		48,651
Other segment assets	4,490,118		4,490,118		4,296,630
Total assets	5,067,942		5,067,942		4,853,320
Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Interest income	2,576	2,241	7,408	6,669
Noninterest income	2,273	1,838	6,484	5,727
Total revenue	4,849	4,079	13,892	12,396
Interest expense	2,576	2,241	7,408	6,669
Noninterest expenses	2,273	1,838	6,484	5,727
Total expenses	4,849	4,079	13,892	12,396
External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	71,371	65,182	209,873	188,684
Total expenses	48,867	47,627	148,035	135,410
WSFS Bank [Member]
Segment Reporting Information [Line Items]
Interest income	42,873	38,777	124,739	112,178
Noninterest income	8,944	9,161	27,615	26,334
Total revenue	51,817	47,938	152,354	138,512
Interest expense	3,688	3,952	11,422	11,413
Noninterest expenses	30,066	32,033	91,066	87,668
Provision for loan losses	1,345	198	5,688	2,320
Total expenses	35,099	36,183	108,176	101,401
Income before taxes	17,683	12,640	47,158	39,887
Capital expenditures	3,487	914	4,603	2,207
Cash and cash equivalents	78,209		78,209		73,395
Goodwill	43,653		43,653		43,517
Other segment assets	4,305,469		4,305,469		4,107,212
Total assets	4,427,331		4,427,331		4,224,124
WSFS Bank [Member] | Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Interest income	879	880	2,626	2,545
Noninterest income	2,028	1,602	5,810	5,041
Total revenue	2,907	2,482	8,436	7,586
Interest expense	1,697	1,361	4,782	4,124
Noninterest expenses	245	236	674	686
Total expenses	1,942	1,597	5,456	4,810
WSFS Bank [Member] | External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	54,724	50,420	160,790	146,098
Total expenses	37,041	37,780	113,632	106,211
Cash Connect [Member]
Segment Reporting Information [Line Items]
Noninterest income	7,138	6,640	20,845	18,974
Total revenue	7,138	6,640	20,845	18,974
Noninterest expenses	4,255	3,993	12,780	11,425
Total expenses	4,255	3,993	12,780	11,425
Income before taxes	2,084	1,982	5,628	5,443
Capital expenditures	1,466	67	4,036	156
Cash and cash equivalents	448,594		448,594		431,527
Other segment assets					2,006
Total assets	448,594		448,594		433,533
Cash Connect [Member] | Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Noninterest income	219	204	601	601
Total revenue	219	204	601	601
Interest expense	394	360	1,156	1,019
Noninterest expenses	624	509	1,882	1,688
Total expenses	1,018	869	3,038	2,707
Cash Connect [Member] | External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	7,357	6,844	21,446	19,575
Total expenses	5,273	4,862	15,818	14,132
Wealth Management [Member]
Segment Reporting Information [Line Items]
Interest income	1,984	2,022	6,024	5,819
Noninterest income	5,583	4,503	16,758	12,983
Total revenue	7,567	6,525	22,782	18,802
Interest expense	172	100	437	316
Noninterest expenses	4,384	3,137	12,426	9,179
Provision for loan losses	108	135	324	693
Total expenses	4,664	3,372	13,187	10,188
Income before taxes	2,737	2,933	9,052	7,944
Capital expenditures	16		29	3
Cash and cash equivalents	2,234		2,234		3,117
Goodwill	5,134		5,134		5,134
Other segment assets	184,649		184,649		187,412
Total assets	192,017		192,017		$ 195,663
Wealth Management [Member] | Inter-Segment Eliminations [Member]
Segment Reporting Information [Line Items]
Interest income	1,697	1,361	4,782	4,124
Noninterest income	26	32	73	85
Total revenue	1,723	1,393	4,855	4,209
Interest expense	485	520	1,470	1,526
Noninterest expenses	1,404	1,093	3,928	3,353
Total expenses	1,889	1,613	5,398	4,879
Wealth Management [Member] | External Customer [Member]
Segment Reporting Information [Line Items]
Total revenue	9,290	7,918	27,637	23,011
Total expenses	$ 6,553	$ 4,985	$ 18,585	$ 15,067