Employee Benefit Plans - Fair Values of the Wesbanco's Pension Plan Assets (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Compensation Related Costs [Abstract]
Net assets available for benefits	$ 186.3	$ 167.9

Defined Benefit Plan Net Assets Available For Benefits.

No definition available.

Name:	wsbc_DefinedBenefitPlanNetAssetsAvailableForBenefits
Namespace Prefix:	wsbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant