CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets
Accounts receivable, allowance for credit losses (in dollars)	$ 1,413	$ 1,921
Liabilities and stockholders' equity
Installment payment agreement, current portion, net of discounts	$ 18	$ 136
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	47,663,276	47,214,077
Common stock, shares outstanding	47,663,276	47,214,077
2022 Notes
Liabilities and stockholders' equity
Unamortized debt costs	$ 1,052
Unamortized debt premium noncurrent	544
Senior unsecured 2024 Notes
Liabilities and stockholders' equity
Unamortized debt costs	2,327	$ 2,961
Unamortized debt premium noncurrent	863	$ 1,142
Senior secured 2026 Notes
Liabilities and stockholders' equity
Unamortized debt costs	1,217
Unamortized debt premium noncurrent	$ 1,618

Amount of allowance for credit loss on accounts receivable, classified as current.

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