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Equity Share Repurchase (Policies) | 6 Months Ended
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Jun. 30, 2019
Equity [Abstract] |
Share Repurchase and Retirement [Policy Text Block] | All of the shares repurchased were treated as retirements and reduced the number of shares issued and outstanding. In addition, the Company recorded the excess of the purchase price over the par value per share as a reduction to additional paid-in capital.

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- Definition Share Repurchase and Retirement [Policy Text Block] + References No definition available. + Details
Name: | adt_ShareRepurchaseandRetirementPolicyTextBlock
Namespace Prefix: | adt_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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