Financing Arrangements (Tables)

9 Months Ended

Sep. 30, 2017

Debt Instrument [Line Items]

Schedule of Convertible Debt Interest Expense [Table Text Block]

During the three and nine months endedSeptember 30, 2017 and 2016, the Company recognized interest cost on the Notes as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Contractual interest cost based on 3.25% of the principal amount per annum	$	2,032	$	2,032	$	6,096	$	4,063
Amortization of debt discount	2,722		2,458		7,964		4,854
Total interest cost	$	4,754	$	4,490	$	14,060	$	8,917

Convertible Debt [Table Text Block]

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

	September 30, 2017			December 31, 2016
Liability component:
Principal amount	$	250,000		$	250,000
Less: debt discount	(63,041		)	(71,005		)
Net carrying amount of liability component	$	186,959		$	178,995
Net carrying amount of equity component	$	67,014		$	67,014