Segment Information (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) segment	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Total revenue	$ 172,498,000	$ 151,939,000
Operating income / (loss)	15,003,000	9,867,000
Total Assets	1,114,545,000		$ 731,687,000
Amortization and depreciation	7,385,000	6,422,000
Additions to property and equipment	4,069,000	3,719,000
Alarm.com
Segment Reporting Information [Line Items]
Amortization and depreciation	7,300,000	6,400,000
Additions to property and equipment	3,500,000	2,600,000
Other
Segment Reporting Information [Line Items]
Amortization and depreciation	100,000	100,000
Additions to property and equipment	100,000	800,000
Operating Segments | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	165,532,000	144,940,000
Operating income / (loss)	17,707,000	10,817,000
Total Assets	1,148,958,000		763,925,000
Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	8,137,000	10,096,000
Operating income / (loss)	(2,853,000)	(872,000)
Total Assets	24,440,000		26,739,000
Intersegment Eliminations | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	(905,000)	(861,000)
Operating income / (loss)	153,000	41,000
Total Assets	(58,848,000)		(58,983,000)
Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Total revenue	(266,000)	(2,236,000)
Operating income / (loss)	(4,000)	$ (119,000)
Total Assets	$ (5,000)		$ 6,000
Segment Concentration Risk | Revenue | Alarm.com
Segment Reporting Information [Line Items]
Concentration risk percentage	95.00%	95.00%
SaaS and license revenue
Segment Reporting Information [Line Items]
Total revenue	$ 107,383,000	$ 91,950,000
SaaS and license revenue | Operating Segments | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	101,263,000	87,412,000
SaaS and license revenue | Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	6,120,000	4,538,000
SaaS and license revenue | Intersegment Eliminations | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	0	0
SaaS and license revenue | Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Total revenue	0	0
Hardware and other revenue
Segment Reporting Information [Line Items]
Total revenue	65,115,000	59,989,000
Hardware and other revenue | Operating Segments | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	64,269,000	57,528,000
Hardware and other revenue | Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	2,017,000	5,558,000
Hardware and other revenue | Intersegment Eliminations | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	(905,000)	(861,000)
Hardware and other revenue | Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Total revenue	(266,000)	(2,236,000)
Software license revenue | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	8,700,000	9,700,000
Software license revenue | Other
Segment Reporting Information [Line Items]
Total revenue	$ 0	$ 0