Basis of Presentation and Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($) payment	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segment payment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) unit	Dec. 31, 2017 USD ($)
Basis Of Presentation And Significant Accounting Policies [Line Items]
Accounts receivable, net	$ 31,800,000		$ 31,800,000		$ 16,500,000
Allowance for doubtful accounts	6,637,000		6,637,000		5,594,000	$ 5,356,000
Provision for doubtful accounts	5,700,000	$ 4,400,000	$ 11,636,000	$ 8,409,000	19,405,000
Capitalized contract costs, expected period of benefit			5 years
Equity method investments	500,000		$ 500,000		3,900,000
Amortization expenses included in interest expense			2,339,000	2,671,000
Sales commission included in accrued expenses and other liabilities	5,400,000		5,400,000		4,900,000
Other long-term obligations	28,700,000		28,700,000		$ 17,600,000
Advertising expenses incurred	17,300,000	8,600,000	$ 30,000,000	21,700,000
Uncertain income tax position, percentage			50.00%
Number of reporting units			2		2
Translation (gain) loss	(1,155,000)	1,592,000	$ (2,855,000)	3,633,000
Issued and unused letters of credit	13,900,000		$ 13,900,000		$ 13,800,000
Vivint Sky Control Panels
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of installed panels			85.00%
2GIG Sale
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of installed panels			15.00%
Other Panels
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of installed panels			1.00%
Interest Expense
Basis Of Presentation And Significant Accounting Policies [Line Items]
Amortization expenses included in interest expense	2,400,000	$ 2,700,000	$ 4,900,000	$ 5,300,000
Minimum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets			2 years
Maximum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets			10 years
Notes Payable
Basis Of Presentation And Significant Accounting Policies [Line Items]
Deferred financing costs	31,500,000		$ 31,500,000		32,400,000
Deferred financing cost, accumulated amortization	$ 59,100,000		$ 59,100,000		54,600,000
Vivint Flex Pay
Basis Of Presentation And Significant Accounting Policies [Line Items]
Number of payment options | payment	3		3
Installment loans available to qualified customers, maximum amount provided by third party	$ 4,000		$ 4,000
Vivint Flex Pay | Minimum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Installment loans available to qualified customers, annual percentage rate	0.00%		0.00%
Installment loans available to qualified customers, term			42 months
Vivint Flex Pay | Maximum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Installment loans available to qualified customers, annual percentage rate	9.99%		9.99%
Installment loans available to qualified customers, term			60 months
Subscriber Contracts | Minimum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Contract with customer, term			3 years
Subscriber Contracts | Maximum
Basis Of Presentation And Significant Accounting Policies [Line Items]
Contract with customer, term			5 years
Revolving Credit Facility
Basis Of Presentation And Significant Accounting Policies [Line Items]
Issued and unused letters of credit	$ 140,300,000		$ 140,300,000
Line of Credit | Revolving Credit Facility
Basis Of Presentation And Significant Accounting Policies [Line Items]
Deferred financing costs	1,600,000		1,600,000		2,100,000
Deferred financing cost, accumulated amortization	10,100,000		10,100,000		9,600,000
Fair Value, Inputs, Level 3
Basis Of Presentation And Significant Accounting Policies [Line Items]
Equity method investments	$ 500,000		$ 500,000		$ 700,000