Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 20,084	$ 57,697	$ 28,598
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	133,709	112,720	110,522
Goodwill impairment	6,689	0	0
Amortization of debt discounts	6,964	6,261	5,735
Amortization of debt issuance costs	3,177	3,600	3,592
Share-based compensation	8,568	11,469	9,925
Deferred income taxes	(3,883)	3,485	(2,430)
Equity in (earnings) losses of investment	(216)	(1,439)	3,918
Gain on disposition of assets, net	(889)	0	(146)
(Gain) loss on extinguishment of long-term debt	(9,239)	18	1,183
Unrealized gain on derivative contracts, net	(601)	(3,383)	(2,324)
Unrealized foreign currency (gain) loss	(2,665)	(628)	1,466
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	(8,419)	(3,050)	20,920
Income tax receivable, net of income tax payable	(22,124)	(4,456)	964
Other current assets	(28,664)	25,383	(9,904)
Accounts payable and accrued liabilities	10,830	(31,265)	(1,818)
Other, net	(14,521)	(6,743)	26,543
Net cash provided by operating activities	98,800	169,669	196,744
Cash flows from investing activities:
Capital expenditures	(20,244)	(140,854)	(137,083)
STL acquisition, net	0	(4,081)	0
Proceeds from sale of assets	963	2,550	25
Other	0	0	1,044
Net cash used in investing activities	(19,281)	(142,385)	(136,014)
Cash flows from financing activities:
Proceeds from convertible senior notes	200,000	0	125,000
Repayment of convertible senior notes	(183,150)	0	(60,365)
Proceeds from term loan	0	35,000	0
Repayment of term loans	(3,500)	(35,442)	(63,807)
Repayment of Nordea Q5000 Loan	(35,714)	(35,714)	(35,714)
Repayment of MARAD Debt	(7,200)	(6,858)	(6,532)
Capped call transactions	(10,625)	0	0
Debt issuance costs	(7,747)	(1,586)	(3,867)
Payments related to tax withholding for share-based compensation	(5,264)	(1,680)	(1,407)
Proceeds from issuance of ESPP shares	622	462	506
Net cash used in financing activities	(52,578)	(45,818)	(46,186)
Effect of exchange rate changes on cash and cash equivalents and restricted cash	1,818	1,636	(1,677)
Net increase (decrease) in cash and cash equivalents and restricted cash	28,759	(16,898)	12,867
Cash and cash equivalents and restricted cash:
Balance, beginning of year	262,561	279,459	266,592
Balance, end of year	$ 291,320	$ 262,561	$ 279,459