Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 57,697	$ 28,598	$ 30,052
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	112,720	110,522	108,745
Amortization of debt discounts	6,261	5,735	4,688
Amortization of debt issuance costs	3,600	3,592	6,154
Share-based compensation	11,469	9,925	10,877
Deferred income taxes	3,485	(2,430)	(54,585)
Equity in (earnings) losses of investment	(1,439)	3,918	2,368
(Gain) loss on disposition of assets, net	0	(146)	39
Loss on extinguishment of long-term debt	18	1,183	397
Unrealized gain on derivative contracts, net	(3,383)	(2,324)	(4,423)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	(3,050)	20,920	(28,424)
Other current assets	25,383	(9,904)	(15,680)
Income tax payable, net of income tax receivable	(4,456)	964	3,949
Accounts payable and accrued liabilities	(31,893)	(352)	33,381
Other, net	6,743	(26,543)	45,900
Net cash provided by operating activities	169,669	196,744	51,638
Cash flows from investing activities:
Capital expenditures	(140,854)	(137,083)	(231,127)
STL acquisition, net	(4,081)	0	0
Proceeds from sale of assets	2,550	25	10,000
Other	0	1,044	0
Net cash used in investing activities	(142,385)	(136,014)	(221,127)
Cash flows from financing activities:
Issuance of convertible senior notes	0	125,000	0
Redemption of convertible senior notes	0	(60,365)	0
Proceeds from term loans	35,000	0	100,000
Repayment of term loans	(35,442)	(63,807)	(194,758)
Repayment of Nordea Q5000 Loan	(35,714)	(35,714)	(35,715)
Repayment of MARAD Debt	(6,858)	(6,532)	(6,222)
Debt issuance costs	(1,586)	(3,867)	(3,717)
Net proceeds from issuance of common stock	0	0	219,504
Payments related to tax withholding for share-based compensation	(1,680)	(1,407)	(2,042)
Proceeds from issuance of ESPP shares	462	506	432
Net cash provided by (used in) financing activities	(45,818)	(46,186)	77,482
Effect of exchange rate changes on cash and cash equivalents and restricted cash	1,636	(1,677)	1,952
Net increase (decrease) in cash and cash equivalents and restricted cash	(16,898)	12,867	(90,055)
Cash and cash equivalents and restricted cash:
Balance, beginning of year	279,459	266,592	356,647
Balance, end of year	$ 262,561	$ 279,459	$ 266,592