Convertible debt (Tables)

3 Months Ended

Mar. 31, 2016

Debt Disclosure [Abstract]

Convertible Debt [Table Text Block]

The Senior Notes consist of the following (in thousands):

	March 31, 2016			December 31, 2015
Liability component:
Principal	$	143,750		$	143,750
Less: debt discount and issuance cost, net of amortization	(26,322		)	(27,890		)
Net carrying amount	$	117,428		$	115,860
Equity component (1)	$	28,714		$	28,714

(1) Recorded in the consolidated balance sheet within additional paid-in capital, net of $1.2 million issuance cost in equity.

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

	Three Months Ended March 31,
	2016		2015
2.0% coupon	$	719	$	719
Amortization of debt issuance costs	204		195
Amortization of debt discount	1,364		1,271
Total	$	2,287	$	2,185