Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income attributable to WSFS	$ 45,704	$ 53,882	$ 36,200	$ 13,023	$ 29,718	$ 38,935	$ 28,740	$ 37,350	$ 148,809	$ 134,743	$ 50,244
Denominator:
Weighted average shares (in shares)									49,298	31,570	31,419
Dilutive potential common shares (in shares)									256	597	884
Weighted average fully diluted shares (in shares)									49,554	32,167	32,303
Earnings per share:
Basic (in dollars per share)	$ 0.88	$ 1.02	$ 0.68	$ 0.34	$ 0.94	$ 1.22	$ 0.91	$ 1.19	$ 3.02	$ 4.27	$ 1.60
Diluted (in dollars per share)	$ 0.88	$ 1.02	$ 0.68	$ 0.33	$ 0.93	$ 1.20	$ 0.89	$ 1.16	$ 3.00	$ 4.19	$ 1.56
Outstanding common stock equivalents having no dilutive effect (in shares)									1	18	2