Stockholders' Equity and Regulatory Capital - Schedule of Capital Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Capital Unit [Line Items]
Total Capital (to risk-weighted assets), Consolidated Bank Capital Amount	$ 1,394,666	$ 761,027
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,345,061	720,734
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,280,061	655,734
Tier 1 Capital (to adjusted tangible assets), Consolidated Bank Capital Amount	$ 1,345,061	$ 720,734
Total Capital (to risk-weighted assets), Consolidated Bank Capital Percent	13.78%	12.71%
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	13.29%	12.04%
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	12.65%	10.95%
Tier 1 Leverage Capital (to adjusted tangible assets), Consolidated Bank Capital Percent	11.54%	10.37%
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	$ 809,730	$ 478,980
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	607,297	359,235
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	455,473	269,426
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Amount	$ 466,088	$ 278,111
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	8.00%	8.00%
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	6.00%	6.00%
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	4.00%	4.00%
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,012,162	$ 598,724
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	809,730	478,980
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	657,906	389,171
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 582,610	$ 347,636
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	10.00%	10.00%
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	8.00%	8.00%
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	5.00%	5.00%
WSFS Bank
Capital Unit [Line Items]
Total Capital (to risk-weighted assets), Consolidated Bank Capital Amount	$ 1,414,791	$ 788,512
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,365,186	748,219
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	1,365,186	748,219
Tier 1 Capital (to adjusted tangible assets), Consolidated Bank Capital Amount	$ 1,365,186	$ 748,219
Total Capital (to risk-weighted assets), Consolidated Bank Capital Percent	14.01%	13.37%
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	13.52%	12.69%
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	13.52%	12.69%
Tier 1 Leverage Capital (to adjusted tangible assets), Consolidated Bank Capital Percent	11.72%	10.82%
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	$ 807,877	$ 471,659
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	605,908	353,744
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	454,431	265,308
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Amount	$ 466,003	$ 276,665
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	8.00%	8.00%
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Percentage	6.00%	6.00%
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	4.00%	4.00%
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,009,846	$ 589,574
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	807,877	471,659
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	656,400	383,223
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 582,504	$ 345,831
Total Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	10.00%	10.00%
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Percentage	8.00%	8.00%
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	5.00%	5.00%