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v3.21.2

Allowance for Credit Losses - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020
Credit Loss [Abstract] |  |  |  |
Accounts receivable, allowance for credit loss, incremental increase (decrease) due to COVID | $ 0.0 | $ 2.0 | $ 0.0 | $ 5.1

X
- Definition Accounts Receivable, Allowance For Credit Loss, Incremental Increase (Decrease) Due To COVID-19 + References No definition available. + Details
Name: | dxm_AccountsReceivableAllowanceForCreditLossIncrementalIncreaseDecreaseDueToCOVID19
Namespace Prefix: | dxm_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_CreditLossAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration