Debt - 2010 Convertible Notes (Details Textual) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017
Debt Instrument [Line Items]
Convertible notes cash paid		$ 34,771
Senior Subordinated Convertible Notes 2010
Debt Instrument [Line Items]
Convertible notes cash paid	$ 34,800
Settlement of conversion obligation by common shares delivered from treasury stock	694,240
Settlement of conversion obligation in excess of par value	$ 28,800