Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Convertible Senior Notes

Convertible senior notes consist of the following (in thousands):

	December 31, 2018						December 31, 2019
	Principal/ Fair Value Amount		Debt Issuance Costs		Net Amount		Principal/ Fair Value Amount		Debt Issuance Costs		Net Amount
4.875% convertible senior notes due 2020	$	113,000	$	1,182	$	111,818	$	1,905	$	—	$	1,905
3.25% convertible senior notes due 2020 *	27,974		—		27,974		—		—		—
3.25% convertible senior notes due 2023 **	—		—		—		50,753		—		50,753
Total convertible senior notes	$	140,974	$	1,182	$	139,792	$	52,658	$	—	$	52,658

* The amounts presented for the 3.25% convertible senior notes due 2020 within the table represent the fair value as of December 31, 2018 (see Note 16 - Fair Value Measurements). The notes were extinguished on August 9, 2019 in connection with the Recapitalization Transaction (defined below).The principal amount of these notes was $29.6 million and nil as of December 31, 2018 and 2019, respectively.

** The amounts presented for the 3.25% convertible senior notes due 2023 within the table represent the fair value as of December 31, 2018 and December 31, 2019 (see Note 16 - Fair Value Measurements). The principal amount of these notes totaled nil and $37.6 million as of December 31, 2018 and 2019, respectively. Also, the amount presented excludes accrued, but unpaid, payment-in-kind interest of $0.4 million as of December 31, 2019.

Term loan consists of the following (in thousands):

	December 31, 2018						December 31, 2019
	Principal Amount**		Debt Discount/ Issuance Costs*		Net Amount		Principal Amount**		Debt Discount/ Issuance Costs*			Net Amount
Term Loan	$	—	$	—	$	—	$	134,801	$	(12,319	)	$	122,482

* The term loan was valued using the discounted cash flow method to determine the implied debt discount. The debt discount and issuance costs are being amortized over the life of the term loan.

** The amount presented excludes accrued, but unpaid, payment-in-kind interest of $1.3 million as of December 31, 2019.

Components of Convertible Senior Notes

Key components of the 4.25% convertible senior notes due 2018 consist of the following (in thousands):

	Year ended December 31,
	2017		2018		2019
Contractual interest expense	$	2,184	$	373	$	—
Amortization of debt issuance costs recognized as interest expense	844		103		—
	$	3,028	$	476	$	—

Key components of the 4.875% convertible senior notes due 2020 consist of the following (in thousands):

	Year ended December 31,
	2017		2018		2019
Contractual interest expense	$	5,509	$	5,509	$	3,370
Amortization of debt issuance costs recognized as interest expense	789		789		460
	$	6,298	$	6,298	$	3,830

Key components of the 3.25% convertible senior notes due 2020 consist of the following (in thousands):

	Year ended December 31,
	2017		2018		2019
Contractual interest expense	$	103	$	815	$	580
Amortization of debt issuance costs recognized as interest expense	—		—		—
	$	103	$	815	$	580

Key components of the 3.25% convertible senior notes due 2023 consist of the following (in thousands):

	Year ended December 31,
	2017		2018		2019
Contractual interest expense	$	—	$	—	$	899
Amortization of debt issuance costs recognized as interest expense	—		—		—
	$	—	$	—	$	899