Basis of Presentation and Summary of Significant Accounting Policies - Subscriber System Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gross carrying amount	$ 3,891,719	$ 3,762,905
Accumulated depreciation	(1,001,074)	(870,222)
Subscriber system assets, net	$ 2,890,645	$ 2,892,683

Aggregate accumulated depreciation of long-lived security system assets.

No definition available.

Name:	adt_SubscriberSystemAssetsAccumulatedDepreciation
Namespace Prefix:	adt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant