XML 49 R45.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Equity Compensation And Employee Benefit Plans (Narrative) (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Maximum shares of common stock | 20,000,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized |  |
Maximum annual shares awarded to employee | 500,000 wern_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberofSharesAwardedPerEmployeePerYear |  |
Shares available for granting additional awards | 7,350,177 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant |  |
Unrecognized compensation cost of non-vested equity compensation awards | $ 10,500,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized |  |
Unrecognized compensation cost of non-vested equity compensation awards expected to be recognized over a weighted average period (years) | 2 years 182 days |  |
Maximum Annual Stock Purchase Plan Contributions By Plan Participants | 20,000 wern_MaximumAnnualStockPurchasePlanContributionsByPlanParticipants |  |
Percentage Of Company Matching Contribution To Employee Stock Purchase Plan | 15.00%wern_PercentageOfContributionToEmployeeStockPurchasePlan |  |
Percentage Of Interest Accrues On Purchase Plan Contributions | 5.25%wern_PercentageOfInterestAccruesOnPurchasePlanContributions |  |
Number Of Participants In Executive Nonqualified Excess Plan | 57 wern_NumberOfParticipantsInExecutiveNonqualifiedExcessPlan |  |
Number of Options granted | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod | 0 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Stock Options |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Maximum period for exercisable options (years and days) | 10 years 0 months 1 day |  |
Stock Options | Minimum |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Vesting period (months) | 24 months |  |
Stock Options | Maximum |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Vesting period (months) | 72 months |  |
Restricted Stock |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Fair value of restricted stock awards vested | $ 5,800,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 5,500,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember | 2,200,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember
Restricted Stock | Minimum |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Vesting period (months) | 12 months |  |
Restricted Stock | Maximum |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Vesting period (months) | 84 months |  |
Performance Shares | Minimum |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Performance Awards, percentage range of target to be earned | 0.00%wern_EquityCompensationArrangementbySharebasedPaymentAwardAwardVestingPercentageEarned / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Vesting period (months) | 12 months |  |
Performance Shares | Maximum |  |  |
Equity Compensation Arrangement by Equity Compensation Award [Line Items] |  |  |
Performance Awards, percentage range of target to be earned | 133.00%wern_EquityCompensationArrangementbySharebasedPaymentAwardAwardVestingPercentageEarned / us-gaap_AwardTypeAxis = us-gaap_PerformanceSharesMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Vesting period (months) | 60 months |  |

X
- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Net number of share options (or share units) granted during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Performance Awards, percentage range of target to be earned. + References No definition available. + Details
Name: | wern_EquityCompensationArrangementbySharebasedPaymentAwardAwardVestingPercentageEarned
Namespace Prefix: | wern_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum annual amount of contributions to employee stock purchase plan made by plan participants. + References No definition available. + Details
Name: | wern_MaximumAnnualStockPurchasePlanContributionsByPlanParticipants
Namespace Prefix: | wern_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of participants in executive nonqualified excess plan (the "excess plan") + References No definition available. + Details
Name: | wern_NumberOfParticipantsInExecutiveNonqualifiedExcessPlan
Namespace Prefix: | wern_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of company matching contribution to employee stock purchase plan. + References No definition available. + Details
Name: | wern_PercentageOfContributionToEmployeeStockPurchasePlan
Namespace Prefix: | wern_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of interest paid by the company on participant purchase plan contributions until purchase is made. + References No definition available. + Details
Name: | wern_PercentageOfInterestAccruesOnPurchasePlanContributions
Namespace Prefix: | wern_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The period of time, measured from grant date, before which an equity-based award expires as specified in the award agreement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | wern_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriod
Namespace Prefix: | wern_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The maximum number of shares that can be awarded per participant per year under an employee share-based payment plan. + References No definition available. + Details
Name: | wern_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberofSharesAwardedPerEmployeePerYear
Namespace Prefix: | wern_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |