Significant accounting policies.

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- Definition

The amount of charity care provided during the period based on the provider's direct and indirect costs of providing charity care services.

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- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

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- Definition

Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity).

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- Definition

Amount of cost for defined contribution plan.

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- Definition

Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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No definition available.

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Percentage employer matches of the employee's percentage contribution matched.

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- Definition

The adjustment to reduce the value of existing agreements that specify the lessee's rights to use the leased property. This expense is charged when the estimates of future profits generated by the leased property are reduced.

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The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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- Definition

Amount of loss from reductions in inventory due to subsequent measurement adjustments, including, but not limited to, physical deterioration, obsolescence, or changes in price levels.

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- Definition

Amount of cost (reversal of cost) for pension benefits. Excludes other postretirement benefits.

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No definition available.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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- Definition

The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Basis of presentation and significant accounting policies - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Allowance for credit losses	$ 0	$ 0	$ 0
Inventory write-offs	1,045	616	310
Impairment of long-lived assets	0	0	0
Cost related to charitable care	$ 4,204	3,653	2,847
Expected dividend yield	0.00%
Percent of employer matching contribution	50.00%
Contributions	$ 1,967	1,589	978
Pension expense	1,494	1,588	984
Severance costs	1,466	1,130	784
Stockholders' equity	410,494	476,526	217,790	$ 112,259
Additional paid-in capital
Significant Accounting Policies [Line Items]
Stockholders' equity	1,099,589	1,111,435	871,442	757,314
Retained earnings (accumulated deficit)
Significant Accounting Policies [Line Items]
Stockholders' equity	$ (685,926)	(631,077)	$ (650,885)	$ (643,655)
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
Restricted Share Unit
Significant Accounting Policies [Line Items]
Stock awards granted, vesting period	3 years
Options
Significant Accounting Policies [Line Items]
Stock awards granted, vesting period	4 years
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	$ 2,958	$ 3,224	$ 2,688
Field equipment under operating leases
Significant Accounting Policies [Line Items]
Equipment write-downs included in cost of revenue	$ 639	$ 409	$ 327
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 \| Field equipment under operating leases
Significant Accounting Policies [Line Items]
Property and equipment useful life	36 months