Summary of Significant Accounting Policies - Summary of Revenue from External Customers by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 4,601	$ 3,173	$ 12,901	$ 5,890
Acutus Direct
Disaggregation of Revenue [Line Items]
Total revenue	2,901	2,674	8,853	5,131
Distribution Agreements
Disaggregation of Revenue [Line Items]
Total revenue	1,700	499	4,048	759
United States | Acutus Direct
Disaggregation of Revenue [Line Items]
Total revenue	2,164	1,790	5,976	3,103
United States | Distribution Agreements
Disaggregation of Revenue [Line Items]
Total revenue	25	77	281	92
Outside the United States | Acutus Direct
Disaggregation of Revenue [Line Items]
Total revenue	737	884	2,877	2,028
Outside the United States | Distribution Agreements
Disaggregation of Revenue [Line Items]
Total revenue	$ 1,675	$ 422	$ 3,767	$ 667