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Debt - Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 0	$ 285	$ 1,294
Interest on borrowings	200	400	1,600
Capital leases			964
Other	218	691	884
Total	476	1,355	4,911
2019 Notes
Debt Instrument [Line Items]
Amortization of debt issuance costs	0	285	1,294
Interest on borrowings	0	363	1,578
Additional interest on default	0	0	191
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Amortization of debt issuance costs	52	8	0
Interest on borrowings	202	3	0
Commitment fee	$ 4	$ 5	$ 0

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