Debt Tables (Tables)

12 Months Ended

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Maturities of Long-term Debt [Table Text Block]

As of December 31, 2017, the aggregate contractual maturities of long-term borrowings for the Term Loan are as follows (dollars in thousands):

Fiscal year:
2018	$	12,250
2019	18,375
2020	24,500
2021	24,500
2022	165,375
Total	$	245,000

Schedule of Long-term Debt Instruments

The following table summarizes information about the equity and liability components of the Convertible Senior Notes (dollars in thousands). The fair values of the respective notes outstanding were measured based on quoted market prices:

	December 31,
	2017			2016
Principal amount of Convertible Senior Notes outstanding	$	167,314		$	167,314
Unamortized discount of liability component	(15,356		)	(20,221		)
Unamortized deferred issuance costs	(2,090		)	(2,753		)
Net carrying amount of liability component	149,868			144,340
Less: current portion	—			—
Long-term debt	$	149,868		$	144,340
Carrying value of equity component, net of issuance costs	$	29,211		$	29,211
Fair value of outstanding Convertible Senior Notes	$	257,245		$	165,223
Remaining amortization period of discount on the liability component	3 years			4 years