Convertible 3.75% Senior Notes (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	[1]
Debt Instrument [Line Items]
Debt discount amortization			$ 4,183	$ 3,678
Amortization of deferred financing costs			456	400
Convertible Notes Payable
Debt Instrument [Line Items]
Interest Expense at 3.75% coupon rate	$ 1,347	$ 1,348	2,695	2,695
Debt discount amortization	2,126	1,868	4,183	3,677
Amortization of deferred financing costs	232	204	456	401
Total interest expense	$ 3,705	$ 3,420	$ 7,334	$ 6,773
Stated interest rate	3.75%	3.75%	3.75%	3.75%	3.75%

[1] Derived from the audited December 31, 2016 financial statements