Debt Obligations - (Tables)

6 Months Ended

Jun. 30, 2013

Debt Obligations [Abstract]

Schedule of carrying value of convertible senior notes [Table Text Block]

The following table reflects the net carrying value of the Notes:

	June 30, 2013		December 31, 2012
Convertible senior notes	$	60,000	$	60,000
Less: Unamortized interest discount	9,653		10,990
Net carrying value of convertible senior notes	$	50,347	$	49,010

Schedule of interest cost recognized on convertible senior notes [Table Text Block]

The following table presents the amount of interest cost recognized relating to the Notes during the three and six months endedJune 30, 2013 and June 30, 2012.

	Three Months Ended				Six Months Ended
	June 30, 2013		June 30, 2012		June 30, 2013		June 30, 2012
Contractual interest coupon	$	562	$	562	$	1,124	$	1,125
Amortization of interest discount	670		608		1,337		1,213
Amortization of debt issuance costs	73		60		145		119
Total interest cost recognized	$	1,305	$	1,230	$	2,606	$	2,457