Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following tables summarize the Company’s financial liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019 (in thousands):

	Carrying Amount as of December 31, 2020		Fair Value Measurements As of December 31, 2020
			Level 1		Level 2		Level 3
3.25% convertible senior notes due in 2023	$	34,134	$	—	$	—	$	34,134
Preferred stock derivative liability		8,062		—		—		8,062

	Carrying Amount as of December 31, 2019		Fair Value Measurements As of December 31, 2019
			Level 1		Level 2		Level 3
3.25% convertible senior notes due in 2023	$	50,753	$	—	$	—	$	50,753
Preferred stock derivative liability		5,247		—		—		5,247

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

The following table provides a reconciliation of the beginning and ending balances of liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3) (in thousands):

3.25% convertible senior notes due 2020
	2020		2019
Balance at January 1,	$	—	$	27,974
Additions		—		7,250
Loss on extinguishment of convertible senior notes		—		10,417
Extinguishment of convertible senior notes		—		(48,170	)
Change in fair value		—		2,529
Balance at December 31,	$	—	$	—

3.25% convertible senior notes due 2023
	2020			2019
Balance at January 1,	$	50,753		$	—
New issuance ($29.6 million face value)		—			37,916
New issuance ($8.0 million face value)		—			10,254
Conversion of convertible senior notes		(20,212	)		—
Change in fair value		2,265			2,583
Payment-in-kind interest		1,328			—
Balance at December 31,	$	34,134		$	50,753

Preferred stock derivative liability
	2020		2019
Balance at January 1,	$	5,247	$	—
New issuance of Series A Preferred Stock		—		4,894
Change in fair value		2,815		353
Balance at December 31,	$	8,062	$	5,247