Long-Term Debt - Convertible Senior Notes Due 2023 (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Aug. 14, 2020 USD ($)	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Repurchase amount	$ 183,200
Gain on extinguishment of long-term debt		$ 9,239	$ 0	$ 9,239	$ (18)
Unamortized debt discount		47,562		47,562
Interest expense		$ 8,007	7,694	$ 22,580	23,635
Convertible Senior Notes Maturing September 2023
Debt Instrument [Line Items]
Interest rate (as a percent)		4.125%		4.125%
Frequency of periodic payment				semi-annually
Maturity date				Sep. 15, 2023
Initial conversion ratio				0.1056133
Initial conversion price per share (in dollars per share) | $ / shares		$ 9.47		$ 9.47
Redemption price as a percentage of principal amount				100.00%
Minimum percentage in aggregate principal amount		25.00%		25.00%
Repurchased principal amount	95,000
Repurchase amount	94,100
Reacquisition of debt component	78,200
Gain on extinguishment of long-term debt	5,900
Unamortized debt discount		$ 2,869		$ 2,869		$ 14,500
Reacquisition of equity component	$ 15,900
Carrying amount of equity component		4,200		4,200		20,100
Carrying amount of equity component, net of tax		$ 3,600		$ 3,600		$ 15,900
Effective interest rate (as a percent)		7.80%		7.80%
Interest expense		$ 1,300	$ 2,100	$ 5,600	$ 6,300