Debt (Tables)

6 Months Ended

Jun. 30, 2018

Debt

Summary of information about the equity and liability components of the convertible senior notes

The carrying amount of the Notes consisted of the following (in thousands):

	June 30,  2018			December 30,  2017
Liability component
Principal	$	400,000		$	400,000
Unamortized debt discount	(44,979		)	(50,499		)
Unamortized debt issuance costs	(6,788		)	(7,622		)
Net carrying amount	$	348,233		$	341,879
Equity component
Net carrying amount	$	57,735		$	57,735

Schedule of components of interest expense

Interest expense related to the Notes was comprised of the following (in thousands):

	Three Months Ended				Six Months Ended
	June 30, 2018		July 1, 2017		June 30, 2018		July 1, 2017
Contractual interest expense	$	1,375	$	1,375	$	2,765	$	1,757
Amortization of debt discount	2,767		2,640		5,520		3,395
Amortization of debt issuance costs	418		398		834		512
	$	4,560	$	4,413	$	9,119	$	5,664