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Long-Term Debt - Schedule Of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Nov. 01, 2016	Dec. 31, 2015	Mar. 31, 2012
Debt Instrument [Line Items]
Carrying value	$ 657,024
Unamortized debt discounts	(19,094)
Unamortized debt issuance costs	(11,963)		$ (11,993)
Total debt	625,967		749,335
Less current maturities	(67,571)		(71,640)
Long-term debt	558,396		677,695
Term Loan Maturing June 2018 [Member]
Debt Instrument [Line Items]
Carrying value	192,258		255,000
Unamortized debt discounts	0
Unamortized debt issuance costs	(1,391)
Less current maturities	(25,634)
Long-term debt	165,233
Convertible Senior Notes Maturing May 2022 [Member]
Debt Instrument [Line Items]
Carrying value	125,000	$ 125,000	0
Unamortized debt discounts	(16,513)	$ (16,900)
Unamortized debt issuance costs	(2,790)
Less current maturities	0
Long-term debt	105,697
Convertible Senior Notes Maturing March 2032 [Member]
Debt Instrument [Line Items]
Carrying value	60,115		200,000	$ 200,000
Unamortized debt discounts	(2,581)		(14,963)	$ (35,400)
Unamortized debt issuance costs	(231)
Less current maturities	0
Long-term debt	57,303
MARAD Debt Maturing February 2027 [Member]
Debt Instrument [Line Items]
Carrying value	83,222		89,148
Unamortized debt discounts	0
Unamortized debt issuance costs	(5,001)
Less current maturities	(6,222)
Long-term debt	71,999
Nordea Q5000 Loan Maturing April 2020 [Member]
Debt Instrument [Line Items]
Carrying value	196,429		$ 232,143
Unamortized debt discounts	0
Unamortized debt issuance costs	(2,550)
Less current maturities	(35,715)
Long-term debt	$ 158,164