Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2016

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, 2016 and 2015:

	December 31,
	2016		2015
Convertible senior notes	$	—	$	60,000
Less: Unamortized interest discount	—		1,893
Less: Unamortized debt issuance costs	—		261
Net carrying value of convertible senior notes	$	—	$	57,846

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, 2016, 2015 and 2014.

	December 31,
	2016		2015		2014
Contractual interest coupon	$	1,186	$	2,250	$	2,250
Amortization of interest discount	1,893		3,334		3,022
Amortization of debt issuance costs	261		432		363
Total interest cost recognized	$	3,340	$	6,016	$	5,635