Loans and the Allowance for Credit Losses - Summary of Age Analysis of Loan Categories (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Current	$ 4,827,728	$ 4,042,825
30-59 Days Past Due	11,089	8,500
60-89 Days Past Due	6,002	9,976
90 Days or More Past Due	28,902	25,465
Total Past Due	45,993	43,941
Total Loans	4,873,721	4,086,766
90 Days or More Past Due and Accruing	1,031	2,288
Loans held for sale, current	6,064wsbc_LoansReceivableHeldForSaleCurrent	5,865wsbc_LoansReceivableHeldForSaleCurrent
Loans held for sale	6,064	5,865
Total loans, current	4,833,792wsbc_LoansReceivableNetCurrent	4,048,690wsbc_LoansReceivableNetCurrent
Total loans	4,879,785us-gaap_LoansReceivableNet	4,092,631us-gaap_LoansReceivableNet
Commercial Real Estate - Land and Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	286,883	261,356
30-59 Days Past Due		20
90 Days or More Past Due	1,192	1,267
Total Past Due	1,192	1,287
Total Loans	288,075	262,643
90 Days or More Past Due and Accruing		71
Commercial Real Estate - Improved Property [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	1,889,451	1,665,363
30-59 Days Past Due	1,093	961
60-89 Days Past Due	1,435	4,772
90 Days or More Past Due	16,890	11,721
Total Past Due	19,418	17,454
Total Loans	1,908,869	1,682,817
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	2,176,334	1,926,719
30-59 Days Past Due	1,093	981
60-89 Days Past Due	1,435	4,772
90 Days or More Past Due	18,082	12,988
Total Past Due	20,610	18,741
Total Loans	2,196,944	1,945,460
90 Days or More Past Due and Accruing		71
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	705,380	634,482
30-59 Days Past Due	916	1,834
60-89 Days Past Due	1,518	240
90 Days or More Past Due	1,807	1,854
Total Past Due	4,241	3,928
Total Loans	709,621	638,410
90 Days or More Past Due and Accruing	3	22
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	1,226,131	915,968
30-59 Days Past Due	4,981	1,237
60-89 Days Past Due	1,673	3,384
90 Days or More Past Due	6,378	8,181
Total Past Due	13,032	12,802
Total Loans	1,239,163	928,770
90 Days or More Past Due and Accruing	74	1,306
Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	357,545	325,291
30-59 Days Past Due	1,982	1,877
60-89 Days Past Due	508	895
90 Days or More Past Due	2,128	1,968
Total Past Due	4,618	4,740
Total Loans	362,163	330,031
90 Days or More Past Due and Accruing	684	570
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	362,338	240,365
30-59 Days Past Due	2,117	2,571
60-89 Days Past Due	868	685
90 Days or More Past Due	507	474
Total Past Due	3,492	3,730
Total Loans	365,830	244,095
90 Days or More Past Due and Accruing	270	319
Non-Accrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	9,209	7,562
30-59 Days Past Due	2,008	2,884
60-89 Days Past Due	2,319	5,552
90 Days or More Past Due	27,838	22,820
Total Past Due	32,165	31,256
Total Loans	41,374	38,818
TDRs Accruing Interest [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	16,536	11,016
30-59 Days Past Due	582	151
60-89 Days Past Due	179	542
90 Days or More Past Due	33	357
Total Past Due	794	1,050
Total Loans	17,330	12,066
Total Impaired [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	25,745	18,578
30-59 Days Past Due	2,590	3,035
60-89 Days Past Due	2,498	6,094
90 Days or More Past Due	27,871	23,177
Total Past Due	32,959	32,306
Total Loans	$ 58,704	$ 50,884

Financing receivables that are less than 60 days past due but more than 29 days past due.

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-Publisher FASB

-Name Accounting Standards Codification

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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