Employee Benefit Plans - Fair Values of the WesBanco's Pension Plan Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	$ 120,363	$ 115,061
Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	21,935	23,741
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	60,144	56,098
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	18,110	16,802
Municipal Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	2,998	3,034
Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	17,176	15,386
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	82,079	79,839
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Registered Investment Companies [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	21,935	23,741
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	60,144	56,098
Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	38,284	35,222
Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	18,110	16,802
Significant Other Observable Inputs (Level 2) [Member] | Municipal Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	2,998	3,034
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage-Backed Securities and Collateralized Mortgage Obligations of Government Agencies [Member]
Defined Benefit Plan Disclosure [Line Items]
Total defined benefit pension plan assets	$ 17,176	$ 15,386