- Components of Interest Expense (Details) - 2016 Convertible Senior Notes - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
2016 Notes:
Amortization of the discount on the liability component	$ 2,064	$ 1,859
Cash interest related to the contractual interest coupon	887	845
Total	2,951	2,704
Amortization of debt discount (premium), interest costs capitalized	100	200
Interest expense, debt, excluding amortization, interest costs capitalized	$ 0	$ 100