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 (loss)	$ 18,748	$ 11,552	$ (7,529)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,769	20,768	17,351
Amortization of National Geographic fee	2,907	2,907	2,907
Amortization of deferred financing costs and other, net	1,875	1,909	2,226
Amortization of right-to-use lease assets	95
Stock-based compensation	3,573	4,405	10,627
Deferred income taxes	1,486	343	8,336
(Gain) loss on foreign currency	(94)	2,175	(1,144)
Write-off of unamortized issuance costs related to debt refinancing		359
Loss on write-off of assets		129
Changes in operating assets and liabilities
Marine operating supplies and inventories	(1,557)	70	(1,036)
Prepaid expenses and other current assets	(8,250)	(716)	575
Lease liabilities	164
Unearned passenger revenues	15,336	11,134	20,709
Other long-term assets	(5,071)	(698)	136
Other long-term liabilities	2,764	(129)	3
Accounts payable and accrued expenses	4,838	2,149	(243)
Net cash provided by operating activities	62,583	56,357	52,918
Cash Flows From Investing Activities
Purchases of property and equipment	(96,002)	(54,345)	(80,485)
Loan issuance	(4,083)
Net cash used in investing activities	(100,085)	(54,345)	(80,485)
Cash Flows From Financing Activities
Proceeds from long-term debt	30,476	200,000
Repayments of long-term debt	(2,000)	(171,625)	(1,750)
Payment of deferred financing costs	(2,372)	(6,490)	(418)
Repurchase under stock-based compensation plans and related tax impacts	(1,786)	(4,510)	(5,034)
Warrants exercised	314
Repurchase of warrants and common stock	(23)	(854)	(6,192)
Net cash provided by (used in) financing activities	24,609	16,521	(13,394)
Effect of exchange rate changes on cash		118	30
Net (decrease) increase in cash, cash equivalents and restricted cash	(12,893)	18,651	(40,931)
Cash, cash equivalents and restricted cash at beginning of period	122,151	103,500	144,431
Cash, cash equivalents and restricted cash at end of period	109,258	122,151	103,500
Supplemental disclosures of cash flow information:
Interest	14,330	13,391	10,478
Income taxes	1,171	522	965
Non-cash investing and financing activities:
Additional paid-in capital exercise proceeds of option shares	225	1,682	1,682
Additional paid-in capital exchange proceeds used for option shares	(225)	(1,682)	(1,682)
Non-cash deemed dividend to warrant holders	$ 2,654