Stockholders' Equity and Regulatory Capital - Schedule of Capital Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Capital Unit [Line Items]
Total Capital (to risk-weighted assets), Consolidated Bank Capital Amount	$ 761,027	$ 659,376
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	720,734	617,945
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	655,734	552,982
Tier 1 Capital (to adjusted tangible assets), Consolidated Bank Capital Amount	$ 720,734	$ 617,945
Total Capital (to risk-weighted assets), Consolidated Bank Capital Percent	12.71%	11.41%
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	12.04%	10.70%
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	10.95%	9.57%
Tier 1 Leverage Capital (to adjusted tangible assets), Consolidated Bank Capital Percent	10.37%	9.15%
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	$ 478,980	$ 462,195
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	359,235	346,646
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	269,426	259,984
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Amount	$ 278,111	$ 270,249
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	$ 598,724	$ 577,743
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	478,980	462,195
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	389,171	375,533
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 347,636	$ 337,812
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	$ 788,512	$ 695,739
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	748,219	654,308
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Amount	748,219	654,308
Tier 1 Capital (to adjusted tangible assets), Consolidated Bank Capital Amount	$ 748,219	$ 654,308
Total Capital (to risk-weighted assets), Consolidated Bank Capital Percent	13.37%	12.08%
Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	12.69%	11.36%
Common Equity Tier 1 Capital (to risk-weighted assets), Consolidated Bank Capital Percent	12.69%	11.36%
Tier 1 Leverage Capital (to adjusted tangible assets), Consolidated Bank Capital Percent	10.82%	9.73%
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	$ 471,659	$ 460,639
Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	353,744	345,480
Common Equity Tier 1 Capital (to risk-weighted assets), For Capital Adequacy Purposes Amount	265,308	259,110
Tier 1 Leverage Capital (to adjusted tangible assets), For Capital Adequacy Purposes Amount	$ 276,665	$ 269,008
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	$ 589,574	$ 575,799
Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	471,659	460,639
Common Equity Tier 1 Capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	383,223	374,270
Tier 1 Leverage Capital (to adjusted tangible assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Amount	$ 345,831	$ 336,260
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%