Debt Obligations - (Tables)

3 Months Ended

Mar. 31, 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:

	March 31, 2013		December 31, 2012
Convertible senior notes	$	60,000	$	60,000
Less: Unamortized interest discount	10,323		10,990
Net carrying value of convertible senior notes	$	49,677	$	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 months endedMarch 31, 2013.

	Three Months Ended
	March 31, 2013		March 31, 2012
Contractual interest coupon	$	562	$	563
Amortization of interest discount	667		605
Amortization of debt issuance costs	72		59
Total interest cost recognized	$	1,301	$	1,227