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Summary of Significant Accounting Policies (Major Customers) (Details) | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020
Dollar General [Member] |  |
Revenue, Major Customer [Line Items] |  |
Percentage of total revenue | 14.00% | 12.00%

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_EntityWideRevenueMajorCustomerLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Revenue of customers that exceed 10% of total company revenue. + References No definition available. + Details
Name: | wern_ReportablePercentageOfRevenueByCustomer
Namespace Prefix: | wern_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | srt_MajorCustomersAxis=wern_DollarGeneralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |