Liabilities (Tables)

3 Months Ended

Mar. 31, 2018

Liabilities

Schedule of accrued expenses and other current liabilities

	March 31,		December 31,
	2018		2017
	(in thousands)
Payroll and related benefits	$	30,890	$	32,996
Warranty	6,455		6,532
Interest	2,148		4,430
Professional fees	3,654		3,942
Merger consideration payable	2,662		2,662
Sales, use, and other taxes	1,493		2,144
Restructuring liability	1,390		1,520
Other	5,605		3,842
Total	$	54,297	$	58,068

Schedule of changes in product warranty reserves

	(in thousands)
Balance - December 31, 2017	$	6,532
Warranties issued	1,647
Consumption of reserves	(1,908		)
Changes in estimate	184
Balance - March 31, 2018	$	6,455

Schedule of restructuring accrual activities

	Personnel
	Severance and			Facility
	Related Costs			Related Costs			Total
	(in thousands)
Balance - December 31, 2017	$	1,520		$	—		$	1,520
Provision	655			1,868			2,523
Payments	(785		)	(1,868		)	(2,653		)
Balance - March 31, 2018	$	1,390		$	—		$	1,390

Schedule of changes in deferred revenue

	(in thousands)
Balance - December 31, 2017	$	70,536
Deferral of revenue	5,360
Recognition of unearned revenue	(27,100		)
Balance - March 31, 2018	$	48,796

Schedule of carrying value of Convertible Senior Notes

	March 31,			December 31,
	2018			2017
	(in thousands)
Principal amount	$	345,000		$	345,000
Unamortized debt discount	(60,424		)	(63,022		)
Unamortized transaction costs	(6,087		)	(6,348		)
Net carrying value	$	278,489		$	275,630

Summary of interest expense related to Convertible Senior Notes

	Three months		Three months
	ended March 31,		ended March 31,
	2018		2017
	(in thousands)
Cash Interest Expense
Coupon interest expense	$	2,329	$	1,915
Non-Cash Interest Expense
Amortization of debt discount	2,598		1,985
Amortization of transaction costs	261		200
Total Interest Expense	$	5,188	$	4,100