Convertible 3.75% Senior Notes (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Debt discount amortization	$ 2,057	$ 1,809
Amortization of deferred financing costs	224	197
Convertible Notes Payable
Debt Instrument [Line Items]
Interest Expense at 3.75% coupon rate	1,348	1,347
Debt discount amortization	2,057	1,809
Amortization of deferred financing costs	224	197
Total interest expense	$ 3,629	$ 3,353
Stated interest rate	3.75%	3.75%	3.75%