Basis of presentation and significant accounting policies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Significant Accounting Policies [Line Items]
Allowance for credit losses	$ 0	$ 0	$ 0
Inventory write-offs	681	917	1,045
Impairment of long-lived assets	0	0	0
Cost related to charitable care	$ 2,692	3,009	4,204
Expected dividend yield	0.00%
Percent of employer matching contribution	50.00%
Contributions	$ 2,375	2,083	1,967
Pension expense	2,672	2,104	1,494
Severance costs	1,735	1,594	1,466
Stockholders' equity	(362,496)	(441,170)	(410,494)	$ (476,526)
Additional paid-in capital
Significant Accounting Policies [Line Items]
Stockholders' equity	(1,353,468)	(1,222,063)	(1,099,589)	(1,111,435)
Retained earnings (accumulated deficit)
Significant Accounting Policies [Line Items]
Stockholders' equity	$ 985,503	$ 778,460	685,926	$ 631,077
Cumulative Effect, Period of Adoption, Adjustment
Significant Accounting Policies [Line Items]
Stockholders' equity			128,972
Cumulative Effect, Period of Adoption, Adjustment | Additional paid-in capital
Significant Accounting Policies [Line Items]
Stockholders' equity			132,474
Cumulative Effect, Period of Adoption, Adjustment | Retained earnings (accumulated deficit)
Significant Accounting Policies [Line Items]
Stockholders' equity			$ (3,502)
Options
Significant Accounting Policies [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Shipping and Handling
Significant Accounting Policies [Line Items]
Direct costs included in sales and marketing costs	$ 2,871	$ 3,211	$ 2,958
Minimum | Restricted Share Unit
Significant Accounting Policies [Line Items]
Stock awards granted, vesting period	2 years
Minimum | Options
Significant Accounting Policies [Line Items]
Stock awards granted, vesting period	2 years
Minimum | Field equipment under operating leases
Significant Accounting Policies [Line Items]
Property and equipment useful life	18 months
Maximum
Significant Accounting Policies [Line Items]
Employer matching contribution, percent of employees' annual salary	3.00%
Maximum | Restricted Share Unit
Significant Accounting Policies [Line Items]
Stock awards granted, vesting period	3 years
Maximum | Options
Significant Accounting Policies [Line Items]
Stock awards granted, vesting period	4 years
Maximum | Field equipment under operating leases
Significant Accounting Policies [Line Items]
Property and equipment useful life	60 months