Convertible 3.75% Senior Notes (Details 2) - USD ($) $ in Thousands		1 Months Ended	5 Months Ended	12 Months Ended
	May 20, 2015	Dec. 31, 2014	May 20, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 16, 2014
Reclassification of derivative liability to equity	$ 18,300			$ 0	$ 18,256	$ 0
Convertible debt
Initial Measurement		$ 41,400			$ 0	$ 41,400	$ 43,700
Decrease in Fair Value		$ 2,300	$ 23,144
Reclassification of derivative liability to equity	$ 18,256