Debt (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Summary of interest expense related to the Convertible Notes
Stated amount at 3.5% coupon rate	$ 1,258	$ 1,258
Amortization of discount	1,626	1,442
Amortization of deferred financing costs	87	77
Convertible Notes interest expense, Net	$ 2,971	$ 2,777