Convertible 3.75% Senior Notes (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt discount amortization	$ 7,599	$ 6,680	$ 261
Amortization of deferred financing costs	828	1,132	107
Convertible Notes Payable
Debt Instrument [Line Items]
Interest Expense at 3.75% coupon rate	5,391	5,391	225
Debt discount amortization	7,599	6,680	261
Amortization of deferred financing costs	828	728	28
Total interest expense	$ 13,818	$ 12,799	$ 514