Segment Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Total revenue	$ 158,851,000	$ 127,880,000	$ 452,427,000	$ 361,875,000
Operating income / (loss)	18,056,000	12,195,000	42,917,000	35,461,000
Total Assets	698,045,000		698,045,000		$ 557,799,000
Amortization and depreciation	6,878,000	5,467,000	20,023,000	15,833,000
Additions to property and equipment			10,677,000	10,660,000
Alarm.com
Segment Reporting Information [Line Items]
Amortization and depreciation	6,700,000	5,500,000	19,800,000	15,800,000
Additions to property and equipment	4,700,000	4,700,000	11,200,000	8,500,000
Other
Segment Reporting Information [Line Items]
Amortization and depreciation	100,000	100,000	200,000	100,000
Additions to property and equipment	100,000	100,000	1,000,000.0	100,000
Operating Segments | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	150,560,000	120,970,000	428,968,000	341,343,000
Operating income / (loss)	18,810,000	12,772,000	45,427,000	37,182,000
Total Assets	729,845,000		729,845,000		589,952,000
Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	9,837,000	10,454,000	31,642,000	29,664,000
Operating income / (loss)	(889,000)	(561,000)	(2,370,000)	(1,782,000)
Total Assets	24,527,000		24,527,000		17,844,000
Intersegment Eliminations | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	(554,000)	(1,287,000)	(2,118,000)	(3,364,000)
Operating income / (loss)	189,000	62,000	246,000	71,000
Total Assets	(56,356,000)		(56,356,000)		(49,997,000)
Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Total revenue	(992,000)	(2,257,000)	(6,065,000)	(5,768,000)
Operating income / (loss)	(54,000)	$ (78,000)	(386,000)	$ (10,000)
Total Assets	$ 29,000		$ 29,000		$ 0
Segment Concentration Risk | Revenue | Alarm.com
Segment Reporting Information [Line Items]
Concentration risk percentage	94.00%	94.00%	94.00%	93.00%
Software license revenue | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	$ 9,500,000	$ 10,800,000	$ 29,000,000.0	$ 32,800,000
Software license revenue | Other
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
SaaS and license revenue
Segment Reporting Information [Line Items]
Total revenue	100,126,000	84,924,000	287,780,000	247,313,000
SaaS and license revenue | Operating Segments | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	92,834,000	79,954,000	269,168,000	233,459,000
SaaS and license revenue | Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	7,292,000	4,970,000	18,612,000	13,854,000
SaaS and license revenue | Intersegment Eliminations | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
SaaS and license revenue | Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Total revenue	0	0	0	0
Hardware and other revenue
Segment Reporting Information [Line Items]
Total revenue	58,725,000	42,956,000	164,647,000	114,562,000
Hardware and other revenue | Operating Segments | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	57,726,000	41,016,000	159,800,000	107,884,000
Hardware and other revenue | Operating Segments | Other
Segment Reporting Information [Line Items]
Total revenue	2,545,000	5,484,000	13,030,000	15,810,000
Hardware and other revenue | Intersegment Eliminations | Alarm.com
Segment Reporting Information [Line Items]
Total revenue	(554,000)	(1,287,000)	(2,118,000)	(3,364,000)
Hardware and other revenue | Intersegment Eliminations | Other
Segment Reporting Information [Line Items]
Total revenue	$ (992,000)	$ (2,257,000)	$ (6,065,000)	$ (5,768,000)