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Goodwill and Intangible Assets, Net - Narrative (Details) - USD ($)		1 Months Ended	3 Months Ended
	Mar. 08, 2017	Jan. 31, 2017	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition [Line Items]
Goodwill acquired			$ 39,379,000
Goodwill impairment			0	$ 0
Amortization			1,493,000	500,000
Impairment of long-lived assets			0	$ 0
Alarm.com
Business Acquisition [Line Items]
Goodwill acquired			$ 39,379,000
Alarm.com \| ObjectVideo
Business Acquisition [Line Items]
Goodwill acquired		$ 2,700,000
Alarm.com \| Connect And Piper
Business Acquisition [Line Items]
Goodwill acquired	$ 36,700,000