Long-Term Debt - Maturities Of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Aug. 14, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Less than one year	$ 73,560
One to two years	70,062
Two to three years	38,333
Three to four years	8,749
Four to five years	9,186
Over five years	214,645
Gross debt	414,535
Unamortized debt discounts	(47,562)
Unamortized debt issuance costs	(10,027)
Total debt	356,946
Less: current maturities	(73,401)		$ (99,731)
Long-term debt	283,545		306,122
Term Loan Maturing December 2021
Debt Instrument [Line Items]
Less than one year	3,500
One to two years	27,125
Two to three years	0
Three to four years	0
Four to five years	0
Over five years	0
Gross debt	30,625		33,250
Unamortized debt discounts	0
Unamortized debt issuance costs	(239)
Total debt	30,386
Less: current maturities	(3,500)
Long-term debt	26,886
Convertible Senior Notes Maturing May 2022
Debt Instrument [Line Items]
Less than one year	0
One to two years	35,000
Two to three years	0
Three to four years	0
Four to five years	0
Over five years	0
Gross debt	35,000		125,000
Unamortized debt discounts	(1,560)		(8,000)
Unamortized debt issuance costs	(235)
Total debt	33,205
Less: current maturities	0
Long-term debt	33,205
Convertible Senior Notes Maturing September 2023
Debt Instrument [Line Items]
Less than one year	0
One to two years	0
Two to three years	30,000
Three to four years	0
Four to five years	0
Over five years	0
Gross debt	30,000		125,000
Unamortized debt discounts	(2,869)		(14,500)
Unamortized debt issuance costs	(462)
Total debt	26,669
Less: current maturities	0
Long-term debt	26,669
Convertible Senior Notes Maturing February 2026
Debt Instrument [Line Items]
Less than one year	0
One to two years	0
Two to three years	0
Three to four years	0
Four to five years	0
Over five years	200,000
Gross debt	200,000	$ 200,000	0
Unamortized debt discounts	(43,133)
Unamortized debt issuance costs	(5,761)
Total debt	151,106
Less: current maturities	0
Long-term debt	151,106
MARAD Debt Maturing February 2027
Debt Instrument [Line Items]
Less than one year	7,560
One to two years	7,937
Two to three years	8,333
Three to four years	8,749
Four to five years	9,186
Over five years	14,645
Gross debt	56,410		63,610
Unamortized debt discounts	0
Unamortized debt issuance costs	(3,171)
Total debt	53,239
Less: current maturities	(7,560)
Long-term debt	45,679
Nordea Q5000 Loan Maturing January 2021
Debt Instrument [Line Items]
Less than one year	62,500
One to two years	0
Two to three years	0
Three to four years	0
Four to five years	0
Over five years	0
Gross debt	62,500		$ 89,286
Unamortized debt discounts	0
Unamortized debt issuance costs	(159)
Total debt	62,341
Less: current maturities	(62,341)
Long-term debt	$ 0