Convertible Senior Notes (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Notes

The Notes consist of the following:

(in thousands)	December 31, 2019			December 31, 2018
Liability:
Principal	$	143,750		$	143,750
Unamortized debt discount	(23,880		)	(29,846		)
Unamortized issuance costs	(2,692		)	(3,364		)
Net carrying amount	$	117,178		$	110,540
Stockholders’ equity:
Debt discount for conversion option	$	33,350		$	33,350
Issuance costs	$	(1,136	)	$	(1,136	)
Net carrying amount	$	32,214		$	32,214

Schedule of Interest Expense Related to the Notes

Interest expense related to the Notes is as follows:

	Year ended December 31,
(in thousands)	2019		2018
Contractual interest expense	$	2,150	$	1,342
Amortization of debt discount	5,966		3,504
Amortization of issuance costs	673		395
Total interest expense	$	8,789	$	5,241

Schedule of Net Impact on Stockholders' Equity of Components of Convertible Debt

The net impact to the Company’s stockholders' equity, included in additional paid-in capital, of the above components of the Notes is as follows:

(in thousands)	December 31, 2019
Conversion option	$	33,350
Purchase of capped calls	$	(8,907	)
Issuance costs	$	(1,136	)
Total	$	23,307