Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2015

Debt Obligations [Abstract]

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

The following table reflects the net carrying value of the Notes as of December 31, 2015 and 2014:

	December 31,
	2015		2014
Convertible senior notes	$	60,000	$	60,000
Less: Unamortized interest discount	1,893		5,227
Net carrying value of convertible senior notes	$	58,107	$	54,773

Interest cost recognized on the convertible senior notes [Table Text Block]

The following table presents the amount of interest cost recognized relating to the Notes during the years ended December 31, 2015, 2014 and 2013.

	December 31,
	2015		2014		2013
Contractual interest coupon	$	2,250	$	2,250	$	2,250
Amortization of interest discount	3,334		3,022		2,740
Amortization of debt issuance costs	432		363		303
Total interest cost recognized	$	6,016	$	5,635	$	5,293