Liabilities (Tables)

3 Months Ended

Mar. 31, 2019

Liabilities

Schedule of accrued expenses and other current liabilities

	March 31,		December 31,
	2019		2018
	(in thousands)
Payroll and related benefits	$	17,722	$	20,486
Warranty		7,226		7,852
Operating lease liabilities		4,797		—
Interest		1,992		4,321
Professional fees		3,059		2,897
Sales, use, and other taxes		1,256		2,670
Restructuring liability		1,720		2,213
Other		6,268		6,011
Total	$	44,040	$	46,450

Schedule of changes in product warranty reserves

	(in thousands)
Balance - December 31, 2018	$	7,852
Warranties issued		1,427
Consumption of reserves		(1,978)
Changes in estimate		(75)
Balance - March 31, 2019	$	7,226

Schedule of restructuring accrual activities

	Personnel		Facility
	Severance and		Related Costs
	Related Costs		and Other		Total
	(in thousands)
Balance - December 31, 2018	$	2,143	$	70	$	2,213
Provision		1,320		110		1,430
Payments		(1,743)		(180)		(1,923)
Balance - March 31, 2019	$	1,720	$	—	$	1,720

Schedule of changes in deferred revenue

	(in thousands)
Balance - December 31, 2018	$	44,415
Deferral of revenue		792
Recognition of previously deferred revenue		(2,887)
Balance - March 31, 2019	$	42,320

Schedule of carrying value of Convertible Senior Notes

	March 31,		December 31,
	2019		2018
	(in thousands)
Principal amount	$	345,000	$	345,000
Unamortized debt discount		(49,537)		(52,336)
Unamortized transaction costs		(4,990)		(5,272)
Net carrying value	$	290,473	$	287,392

Schedule of interest expense related to Convertible Senior Notes

	Three months ended March 31,
	2019		2018
	(in thousands)
Cash Interest Expense
Coupon interest expense	$	2,329	$	2,329
Non-Cash Interest Expense
Amortization of debt discount		2,799		2,598
Amortization of transaction costs		282		261
Total Interest Expense	$	5,410	$	5,188