Condensed Consolidated Statements Of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Statement of Cash Flows [Abstract]
Net income (loss)	$ (8,478)	$ 18,141
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	65,567	56,512
Goodwill impairment	6,689	0
Amortization of debt discounts	3,316	3,070
Amortization of debt issuance costs	1,619	1,896
Share-based compensation	4,245	6,501
Deferred income taxes	(7,098)	845
Equity in losses of investment	22	69
Gain on disposition of assets, net	(473)	0
Loss on extinguishment of long-term debt	0	18
Unrealized gain on derivative contracts, net	(601)	(1,740)
Unrealized foreign currency loss	10,433	(568)
Changes in operating assets and liabilities:
Accounts receivable, net	(44,698)	(30,656)
Income tax receivable	(19,078)	(3,122)
Other current assets	(23,751)	(2,957)
Accounts payable and accrued liabilities	35,219	665
Other, net	16,891	16,113
Net cash provided by operating activities	6,042	32,561
Cash flows from investing activities:
Capital expenditures	(17,579)	(27,458)
STL acquisition, net	0	(4,081)
Proceeds from sale of assets	498	2,525
Net cash used in investing activities	(17,081)	(29,014)
Cash flows from financing activities:
Proceeds from term loan	0	35,000
Repayment of term loans	(1,750)	(33,692)
Repayment of Nordea Q5000 Loan	(17,858)	(17,857)
Repayment of MARAD Debt	(3,556)	(3,387)
Debt issuance costs	(310)	(1,485)
Payments related to tax withholding for share-based compensation	(5,150)	(1,329)
Proceeds from issuance of ESPP shares	475	281
Net cash used in financing activities	(28,149)	(22,469)
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(2,879)	605
Net decrease in cash and cash equivalents and restricted cash	(42,067)	(18,317)
Cash and cash equivalents and restricted cash:
Balance, beginning of year	262,561	279,459
Balance, end of period	$ 220,494	$ 261,142