Current and Long-Term Debt - Convertible Notes Interest Expense (Details) - Convertible Senior Notes 1.00 percent due December 2020 - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Long-Term Debt
Cash interest per contractual coupon rate	$ 288	$ 719	$ 1,693	$ 2,157
Amortization of note discount	1,214	2,854	7,112	8,450
Amortization of debt issuance costs	97	216	558	633
Total interest expense related to Convertible Notes	$ 1,599	$ 3,789	$ 9,363	$ 11,240

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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