Revenue - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Typical payment receipt, period post shipment			30 days
Sales-type lease, revenue	$ 0	$ 0	$ 0	$ 0	$ 700,000
Training provided with sale of system, period			180 days
Contract with customer, liability	$ 10,680,000	11,824,000	$ 10,680,000	11,824,000	11,237,000	$ 11,403,000	$ 11,779,000	$ 14,222,000
Minimum
Disaggregation of Revenue [Line Items]
Capitalized costs, expected period of benefit	2 years		2 years
Maximum
Disaggregation of Revenue [Line Items]
Capitalized costs, expected period of benefit	3 years		3 years
Sales and marketing
Disaggregation of Revenue [Line Items]
Amortization expense	$ 400,000	$ 600,000	$ 1,400,000	$ 2,000,000
Other Assets
Disaggregation of Revenue [Line Items]
Capitalized contract costs	3,800,000		$ 3,800,000		3,400,000
Service
Disaggregation of Revenue [Line Items]
Extended service contract, option one, term			1 year
Extended service contract, option two, term			2 years
Extended service contract, option three, term			3 years
Loyalty
Disaggregation of Revenue [Line Items]
Contract with customer, liability	$ 400,000		$ 400,000		$ 300,000
Skincare | Japan
Disaggregation of Revenue [Line Items]
Sale of third-party product, warranty period			90 days
Transferred over Time | Service
Disaggregation of Revenue [Line Items]
Revenue from performance obligations transferred to customers, percent	12.00%	15.00%	12.00%	17.00%