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Commitments and Contingencies - Rental Expense and Letters of Credit (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2015 | Sep. 30, 2014 | Sep. 30, 2013
Operating Lease Obligations |  |  |  |
Rental expense under operating leases with initial terms exceeding one year | $ 242,000 | $ 1,691,000 | $ 965,000 | $ 900,000
Self-insured health insurance coverage |  |  |  |
Obligations related to health insurance and self-insured workers' compensation |  |  |  |
Unused letters of credit |  | 1,767,000 |  |
Self-insured retention on workers' compensation claims |  |  |  |
Obligations related to health insurance and self-insured workers' compensation |  |  |  |
Unused letters of credit |  | $ 233,000 |  |

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- Definition Operating Lease Obligations [Line Items] + References No definition available. + Details
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- Definition Rental expense for the reporting period incurred under operating leases with initial terms exceeding one year. + References No definition available. + Details
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Namespace Prefix: | dwsn_
Data Type: | xbrli:monetaryItemType
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- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- References No definition available. + Details
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- Details
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- Details
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