Convertible 3.75% Senior Notes (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	[1]
Debt Instrument [Line Items]
Debt discount amortization			$ 6,376	$ 5,606
Amortization of deferred financing costs			695	611
Convertible Notes Payable
Debt Instrument [Line Items]
Interest Expense at 3.75% coupon rate	$ 1,348	$ 1,348	4,043	4,043
Debt discount amortization	2,193	1,929	6,376	5,606
Amortization of deferred financing costs	239	210	695	611
Total interest expense	$ 3,780	$ 3,487	$ 11,114	$ 10,260
Stated interest rate	3.75%	3.75%	3.75%	3.75%	3.75%

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