Stockholders' Equity and Regulatory Capital - Schedule of Capital Position (Detail) $ in Thousands	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Capital Unit [Line Items]
Total Capital (to risk-weighted assets), Consolidated Bank Capital Amount	$ 1,415,780	$ 1,394,666
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,286,150	1,345,061
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,221,150	1,280,061
Tier 1 Capital (to adjusted tangible assets), Consolidated Bank Capital Amount	$ 1,286,150	$ 1,345,061
Total Capital (to risk-weighted assets), Consolidated Bank Capital Percent	0.1376	0.1378
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	0.1250	0.1329
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	11.87%	12.65%
Tier 1 Leverage Capital (to adjusted tangible assets), Consolidated Bank Capital Percent	0.0976	0.1154
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	$ 823,355	$ 809,730
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	617,517	607,297
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	463,137	455,473
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Amount	$ 527,192	$ 466,088
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	0.0800	0.0800
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	0.0600	0.0600
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	4.50%	4.50%
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Percentage	0.0400	0.0400
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,029,194	$ 1,012,162
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	823,355	809,730
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	668,976	657,906
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 658,990	$ 582,610
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	0.1000	0.1000
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	0.0800	0.0800
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	6.50%	6.50%
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	0.0500	0.0500
WSFS Bank
Capital Unit [Line Items]
Total Capital (to risk-weighted assets), Consolidated Bank Capital Amount	$ 1,412,290	$ 1,414,791
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,283,022	1,365,186
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,283,022	1,365,186
Tier 1 Capital (to adjusted tangible assets), Consolidated Bank Capital Amount	$ 1,283,022	$ 1,365,186
Total Capital (to risk-weighted assets), Consolidated Bank Capital Percent	0.1376	0.1401
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	0.1250	0.1352
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	12.50%	13.52%
Tier 1 Leverage Capital (to adjusted tangible assets), Consolidated Bank Capital Percent	0.0974	0.1172
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	$ 821,012	$ 807,877
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	615,759	605,908
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	461,819	454,431
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Amount	$ 526,803	$ 466,003
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	0.0800	0.0800
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	0.0600	0.0600
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	4.50%	4.50%
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Percentage	0.0400	0.0400
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,026,265	$ 1,009,846
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	821,012	807,877
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	667,073	656,400
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 658,503	$ 582,504
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	0.1000	0.1000
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	0.0800	0.0800
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	6.50%	6.50%
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	0.0500	0.0500