Segment Information - Net Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 1,654,735	$ 571,752
Goodwill	472,828	472,828	$ 166,007
Other segment assets	12,206,351	11,211,722
Total assets	14,333,914	12,256,302
WSFS Bank
Segment Reporting Information [Line Items]
Cash and cash equivalents	1,246,394	202,792
Goodwill	452,629	452,629	$ 145,808
Other segment assets	11,963,345	10,982,681
Total assets	13,662,368	11,638,102
Cash Connect
Segment Reporting Information [Line Items]
Cash and cash equivalents	397,878	357,494
Goodwill	0	0
Other segment assets	6,997	6,555
Total assets	404,875	364,049
Wealth Management
Segment Reporting Information [Line Items]
Cash and cash equivalents	10,463	11,466
Goodwill	20,199	20,199
Other segment assets	236,009	222,486
Total assets	$ 266,671	$ 254,151