Loans and the Allowance for Credit Losses - Summary of Age Analysis of Loan Categories (Parenthetical) (Detail)	6 Months Ended
Jun. 30, 2018
Receivables [Abstract]
Past due loans excluded TDRs past due and accruing	90 days

Loans 90 days or more past due and accruing interest exclude TDRs 90 days or more past due and accruing interest

No definition available.

Name:	wsbc_LoansPastDueAndAccruingInterestExcludingTdrs
Namespace Prefix:	wsbc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration