Debt, Commitments and Contingencies - Legal Proceedings (Details) - Pending Litigation - patent								1 Months Ended			9 Months Ended
	May 26, 2020	Nov. 11, 2019	Oct. 22, 2019	Jul. 24, 2019	Jun. 26, 2017	Aug. 19, 2016	Jun. 02, 2015	Sep. 30, 2017	May 31, 2017	Mar. 31, 2017	Sep. 30, 2020
Vivint, Inc. vs. Alarm.com Holdings, Inc
Loss Contingencies [Line Items]
Number of patents allegedly infringed upon by the company				2	4	5	6		3	2
Number of patents under reexamination								2
Number of patents found to be unpatentable											9
Number of patents allegedly infringed by elements in solution							1
EcoFactor, Inc. vs. Alarm.com Holdings, Inc.
Loss Contingencies [Line Items]
Number of patents allegedly infringed upon by the company	4	3	3