Convertible 3.75% Senior Notes (Details 2) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Debt Instrument [Line Items]
Interest Expense at 3.75% coupon rate		$ 0	$ 1,348
Debt discount amortization		1,809	1,590
Amortization of deferred financing costs		197	195
Convertible Notes Payable [Member]
Debt Instrument [Line Items]
Interest Expense at 3.75% coupon rate		1,347	1,348
Debt discount amortization		1,809	1,590
Amortization of deferred financing costs		197	173
Total interest expense	[1]	$ 3,353	$ 3,111

[1] Included within "Interest and other expense, net" on the Consolidated Statements of Operations