Debt and Commitments (Details 3) (Convertible Debt [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Instrument [Line Items]
Interest expense on convertible notes	$ 1,777	$ 4,269	$ 4,089
Coupon [Member] | 3.375% Convertible Notes [Member]
Debt Instrument [Line Items]
Interest expense on convertible notes	1,046	1,878	1,878
Debt discount amortization [Member] | 3.375% Convertible Notes [Member]
Debt Instrument [Line Items]
Interest expense on convertible notes	$ 731	$ 2,391	$ 2,211