Liabilities (Tables)

6 Months Ended

Jun. 30, 2020

Liabilities

Schedule of accrued expenses and other current liabilities

	June 30,		December 31,
	2020		2019
	(in thousands)
Payroll and related benefits	$	21,267	$	15,174
Warranty		5,518		7,067
Operating lease liabilities		4,104		4,196
Interest		3,750		4,321
Professional fees		1,171		2,443
Sales, use, and other taxes		2,533		811
Restructuring liability		1,233		2,841
Other		2,730		4,390
Total	$	42,306	$	41,243

Schedule of changes in product warranty reserves

		(in thousands)
Balance - December 31, 2019	$	7,067
Warranties issued		1,614
Consumption of reserves		(3,280)
Changes in estimate		117
Balance - June 30, 2020	$	5,518

Schedule of restructuring accrual activities

	(in thousands)
Balance - December 31, 2019	$	2,841
Provision		1,097
Payments		(2,705)
Balance - June 30, 2020	$	1,233

Schedule of changes in deferred revenue

	(in thousands)
Balance - December 31, 2019	$	28,249
Deferral of revenue		6,180
Recognition of previously deferred revenue		(16,054)
Balance - June 30, 2020	$	18,375

Schedule of carrying value of Convertible Senior Notes

		June 30, 2020						December 31, 2019
		2023 Notes		2027 Notes		Total		2023 Notes		2027 Notes		Total
		(in thousands)
Principal amount	$	256,695	$	125,000	$	381,695	$	345,000	$	—	$	345,000
Unamortized debt discount		(25,816)		(33,773)		(59,589)		(40,820)		—		(40,820)
Unamortized transaction costs		(2,601)		(2,191)		(4,792)		(4,112)		—		(4,112)
Net carrying value	$	228,278	$	89,036	$	317,314	$	300,068	$	—	$	300,068

Schedule of interest expense related to Convertible Senior Notes

	Three months ended June 30,				Six months ended June 30,
	2020		2019		2020		2019
	(in thousands)
Cash Interest Expense
Coupon interest expense - 2023 Notes	$	2,070	$	2,329	$	4,399	$	4,658
Coupon interest expense - 2027 Notes		573		—		573		—
Non-cash Interest Expense
Amortization of debt discount - 2023 Notes		2,729		2,851		5,746		5,650
Amortization of debt discount - 2027 Notes		425		—		425		—
Amortization of transaction costs - 2023 Notes		275		287		579		569
Amortization of transaction costs - 2027 Notes		28		—		28		—
Total Interest Expense	$	6,100	$	5,467	$	11,750	$	10,877