Debt (Tables)

9 Months Ended

Sep. 28, 2019

Debt Disclosure [Abstract]

Components of Convertible Senior Notes

The net carrying amounts of the debt obligation were as follows (in thousands):

	September 28, 2019			December 29, 2018
Principal	$	402,500		$	402,500
Unamortized discount (1)	(114,219		)	(127,264		)
Unamortized issuance cost (1)	(7,456		)	(8,307		)
Net carrying amount	$	280,825		$	266,929

⁽¹⁾ 

Unamortized debt conversion discount and issuance costs will be amortized over the remaining life of the 2024 Notes, which is approximately 60 months.

Interest Expense Recognized Related To Notes

The following table sets forth total interest expense recognized related to the 2024 Notes (in thousands): 

	Three Months Ended		Nine Months Ended
	September 28, 2019		September 28, 2019
Contractual interest expense	$	2,138	$	6,415
Amortization of debt issuance costs	290		851
Amortization of debt discount	4,456		13,045
Total interest expense	$	6,884	$	20,311

The following table sets forth total interest expense recognized related to the 2018 Notes (in thousands): 

	Three Months Ended		Nine Months Ended
	September 29, 2018		September 29, 2018
Contractual interest expense	—		1,094
Amortization of debt issuance costs	—		402
Amortization of debt discount	—		4,671
Total interest expense	$	—	$	6,167