Slicers (applies to each fact value in each table cell)

Reporting Entity [Axis]

0001084048 (http://www.sec.gov/CIK)

Long-term Debt, Unclassified [Abstract]	Period [Axis]
	2016-01-01 - 2016-12-31
Long-term Debt, Unclassified [Abstract]
Convertible Debt [Table Text Block]	The following table provides additional information related to our Convertible Notes (in thousands):   2016   2015 Additional paid-in capital $ 37,700   $ 37,700 Principal amount of Convertible Notes $ 402,500   $ 402,500 Unamortized discount of the liability component 40,356   48,064 Carrying amount of debt issuance costs 7,002   8,219 Net carrying amount of Convertible Notes $ 355,142   $ 346,217
Interest Expense Related To Convertible Notes [Table Text Block]	The following table provides the components of interest expense related to our Convertible Notes (in thousands):   2016   2015   2014 Cash interest expense (coupon interest expense) $ 13,081   $ 13,081   $ 6,980 Non-cash amortization of discount on Convertible Notes 7,707   7,274   3,712 Amortization of debt issuance costs 1,217   1,109   551 Total interest expense related to Convertible Notes $ 22,005   $ 21,464   $ 11,243
Schedule of Long-term Debt Instruments [Table Text Block]	Long-term debt as of December 31, 2016 and 2015 consists of the following (in thousands):     2016   2015 Senior Notes $ 247,359   $ 246,750 Convertible Notes 362,144   354,436 Less: Deferred issuance costs(1) (7,757 )   (9,149 ) Total long-term debt $ 601,746   $ 592,037 Less: Current portion —   — Total long-term debt, less current portion $ 601,746   $ 592,037
Schedule of Maturities of Long-term Debt [Table Text Block]	At December 31, 2016, future principal payments for debt were as follows (in thousands): Years Ended December 31,   2017 $ — 2018 — 2019 — 2020 250,000 2021 402,500 Thereafter —   $ 652,500