Current and Long-Term Debt - Convertible Notes Interest (Details) - Convertible Notes - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest Expense, Debt [Abstract]
Cash interest per contractual coupon rate	$ 1,885	$ 2,875	$ 2,875
Amortization of note discount	7,921	11,341	10,762
Amortization of debt issuance costs	623	855	772
Total interest expense related to Convertible Notes	$ 10,429	$ 15,071	$ 14,409