Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2021

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 March 31, 2021 and December 31, 2020 (in thousands):

			Fair Value Measurements as of March 31, 2021
	Carrying Amount as of March 31, 2021		Level 1		Level 2		Level 3
3.25% convertible senior notes due in 2023	$	37,708	$	—	$	—	$	37,708
Preferred stock derivative liability		15,438		—		—		15,438

			Fair Value Measurements as of December 31, 2020
	Carrying Amount 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		8,063		—		—		8,063

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

The following tables provide 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 in 2023	2021			2020
Balance, January 1,	$	34,134		$	50,753
Conversion of convertible senior notes		(5,631	)		—
Change in fair value		9,047			(7,675	)
PIK interest		158			667
Balance, March 31,	$	37,708		$	43,745

Preferred stock derivative liability	2021		2020
Balance, January 1,	$	8,063	$	5,247
Change in fair value		7,375		(2,082	)
Balance, March 31,	$	15,438	$	3,165