Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	*Basis of Presentation* The accompanying unaudited condensed consolidated financial statements and footnotes have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding unaudited interim financial information and include the accounts and transactions of the Company. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the Company’s financial statements for the periods presented. Operating results for the periods presented are not necessarily indicative of the results of operations to be expected for the full year due to seasonality and other factors. Certain information and footnote disclosures normally included in the consolidated financial statements in accordance with U.S. GAAP have been omitted in accordance with the rules and regulations of the SEC for interim reporting. All intercompany balances and transactions have been eliminated in these unaudited condensed consolidated financial statements. These unaudited condensed consolidated financial statements and footnotes should be read in conjunction with the audited consolidated financial statements and accompanying notes thereto for the year ended December 31, 2020 contained in the Company’s Annual Report on Form 10-K filed with the SEC on March 12, 2021 (the “2020 Annual Report”). There have been no significant changes to the Company’s accounting policies from those disclosed in the 2020 Annual Report.
Return to Operations, Policy [Policy Text Block]	*Return to Fleet Operations* The Company resumed ship operations in June 2021 and as of November 2, 2021 had eight of its ten vessels providing expeditions to guests. During June 2021, the Company launched three ships in Alaska and another in the Galapagos, and during the third quarter the Company resumed operations on the majority of its remaining vessels with additional ships operating in Alaska, the Galapagos, Iceland and the Pacific Northwest. The Company continues to work with local authorities on plans to operate in additional geographies, such as Antarctica, during the remainder of the year and early 2022. As the COVID-19 virus effects travel restrictions in various locations around the world, the Company also continues to work with its guests to reschedule travel plans and refund payments or issue future travel certificates, as applicable, for those expeditions and trips that the Company is not able to operate. The Company believes there are a variety of strategic advantages that enable it to deploy its ships safely and quickly, while mitigating the risk of COVID-19 as travel restrictions are lifted. The most notable is the size of its owned and operated vessels which range from 48 to 148 passengers, allowing for a highly controlled environment that includes stringent cleaning protocols. The small nature of the Company’s ships also allows it to efficiently and effectively test its guests and crew prior to boarding. Additionally, all guests age 12 and older, crew and staff are required to be fully vaccinated and the majority of expeditions take place in remote locations where human interactions are limited, so there is less opportunity for external influence. While the Company’s ships were not in operations, the majority of the fleet was being maintained with minimally required crew on-board to ensure they complied with all necessary regulations and could be fully put back into service quickly as needed. Ahead of launching each ship, crew levels were increased as necessary to prepare each vessel for operations as well as for crew training and vaccinations. The Company’s offices primarily remain closed, and most employees are working remotely to maintain general business operations, to provide assistance to existing and potential guests and to maintain information technology systems. The Company continues to adhere to the comprehensive plan it implemented in March 2020 to mitigate the impact of COVID-19 and preserve and enhance its liquidity position. Prior to resuming operations, this plan employed a variety of cost reduction and cash preservation measures including significantly reducing ship and land-based expedition costs such as capital expenditures, crew payroll, land costs, fuel and food, and meaningfully reducing general and administrative expenses through reduced payroll and the elimination of all non-essential travel, office expenses and discretionary spending. The Company also accessed available capital under existing debt facilities and through the issuance of preferred stock. With the majority of operations resuming, operating costs are ramping back up, but given the continued uncertainty around COVID-19 and given that guest counts have not yet returned to traditional levels, the Company continues to minimize expenditures as appropriate.
Balance Sheet and Liquidity, Policy [Policy Text Block]	*Balance Sheet and Liquidity* As of September 30, 2021, the Company had $155.6 million in unrestricted cash and $29.5 million in restricted cash primarily related to deposits on future travel originating from U.S. ports and credit card reserves. During August 2021, the Company received a $21.0 million grant under the Coronavirus Economic Relief for Transportation Services (“CERTS”) Act, which provided grants to eligible motorcoach, school bus, passenger vessel, and pilotage companies, see Note 4 — Financial Statement Details for additional information. As of September 30, 2021, the Company had a total debt position of $561.8 million and was in compliance with all of its debt covenants. During September 2021, the Company drew down $46.2 million under its second export credit agreement in conjunction with its final payment upon delivery of the National Geographic Resolution. In April 2021 the Company drew down $15.5 million under the second export credit agreement in conjunction with its fourth installment payment for the vessel. During June 2021, the Company amended its export credit agreements to, among other things, extend the deferral of scheduled amortization payments of the first export credit facility through December 2021 in the aggregate amount of $15.7 million, extend the waiver of its total net leverage ratio covenant through March 31, 2022, increase the interest rate spreads of the export credit facilities by 50 basis points and annualize EBITDA used in its covenant calculation through December 31, 2022. The deferred principal payments will amortize quarterly over three years starting in March 2022. Certain other covenants continue to be more restrictive during the extended covenant waiver period. During April 2021, the Company amended its term loan and revolving credit facilities to, among other things, extend the waiver of its total net leverage ratio covenant through March 31, 2022, annualize EBITDA used in its covenant calculation through December 31, 2022 and increase the interest rate spreads of the term loan, excluding the Main Street Loan, and the revolving credit facility by an additional 50 basis points. Certain other covenants continue to be more restrictive during the extended covenant waiver period. Given the dynamic and unpredictable nature of the COVID-19 pandemic, the Company cannot reasonably estimate the potential impacts the pandemic will have on its financial condition, results of operations, cash flows, plans and growth for the foreseeable future. It is unknown when full travel restrictions and various remaining border closures will be lifted and what the demand for expedition travel will be once restrictions are no longer in place. Based on the actions taken to date by the Company, its planned and anticipated actions and its current forecast, the Company believes that it can meet its obligations for the next 12 months from November 2, 2021, the date of this Quarterly Report on Form 10-Q.
New Accounting Pronouncements, Policy [Policy Text Block]	*Recently Adopted Accounting Pronouncements* In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes. The amendments of this ASU are intended to simplify the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company adopted this ASU as required, and it has not had, nor is it expected to have, a material impact to the Company’s financial statements. *Recent Accounting Pronouncements* In March 2020, the FASB issued ASU 2020-4, Reference Rate Reform (Topic 848)—Facilitation of the Effects of Reference Rate Reform on Financial Reporting. The guidance of this ASU is designed to provide relief from the accounting analysis and impacts that may otherwise be required for modifications to agreements (e.g., loans, debt securities, derivatives, borrowings) necessitated by reference rate reform. It also provides optional expedients to enable companies to continue to apply hedge accounting to certain hedging relationships impacted by reference rate reform. Application of the guidance is optional, is only available in certain situations, and is only available for companies to apply until December 31, 2022. The Company is currently reviewing its agreements impacted by the reference rate reform and does not expect this ASU to have a material impact to the Company’s financial statements. In August 2020, the FASB issued ASU 2020-06, Debt–Debt with conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40)—Accounting for Convertible Instruments and Contracts in an Entity's Own Equity. The amendments in this ASU address issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. The amendments reduce the number of accounting models for convertible debt instruments and convertible preferred stock, and address convertible instruments with conversion features, as well as other items. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. The Company will adopt this ASU as required and does not expect it to have a material impact to the Company’s financial statements.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2021

Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements and footnotes have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (the “SEC”) regarding unaudited interim financial information and include the accounts and transactions of the Company. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the Company’s financial statements for the periods presented. Operating results for the periods presented are not necessarily indicative of the results of operations to be expected for the full year due to seasonality and other factors. Certain information and footnote disclosures normally included in the consolidated financial statements in accordance with U.S. GAAP have been omitted in accordance with the rules and regulations of the SEC for interim reporting. All intercompany balances and transactions have been eliminated in these unaudited condensed consolidated financial statements. These unaudited condensed consolidated financial statements and footnotes should be read in conjunction with the audited consolidated financial statements and accompanying notes thereto for the year ended December 31, 2020 contained in the Company’s Annual Report on Form 10-K filed with the SEC on March 12, 2021 (the “2020 Annual Report”).

There have been no significant changes to the Company’s accounting policies from those disclosed in the 2020 Annual Report.

Return to Operations, Policy [Policy Text Block]

Return to Fleet Operations

The Company resumed ship operations in June 2021 and as of November 2, 2021 had eight of its ten vessels providing expeditions to guests. During June 2021, the Company launched three ships in Alaska and another in the Galapagos, and during the third quarter the Company resumed operations on the majority of its remaining vessels with additional ships operating in Alaska, the Galapagos, Iceland and the Pacific Northwest. The Company continues to work with local authorities on plans to operate in additional geographies, such as Antarctica, during the remainder of the year and early 2022. As the COVID-19 virus effects travel restrictions in various locations around the world, the Company also continues to work with its guests to reschedule travel plans and refund payments or issue future travel certificates, as applicable, for those expeditions and trips that the Company is not able to operate.

The Company believes there are a variety of strategic advantages that enable it to deploy its ships safely and quickly, while mitigating the risk of COVID-19 as travel restrictions are lifted. The most notable is the size of its owned and operated vessels which range from 48 to 148 passengers, allowing for a highly controlled environment that includes stringent cleaning protocols. The small nature of the Company’s ships also allows it to efficiently and effectively test its guests and crew prior to boarding. Additionally, all guests age 12 and older, crew and staff are required to be fully vaccinated and the majority of expeditions take place in remote locations where human interactions are limited, so there is less opportunity for external influence.

While the Company’s ships were not in operations, the majority of the fleet was being maintained with minimally required crew on-board to ensure they complied with all necessary regulations and could be fully put back into service quickly as needed. Ahead of launching each ship, crew levels were increased as necessary to prepare each vessel for operations as well as for crew training and vaccinations. The Company’s offices primarily remain closed, and most employees are working remotely to maintain general business operations, to provide assistance to existing and potential guests and to maintain information technology systems.

The Company continues to adhere to the comprehensive plan it implemented in March 2020 to mitigate the impact of COVID-19 and preserve and enhance its liquidity position. Prior to resuming operations, this plan employed a variety of cost reduction and cash preservation measures including significantly reducing ship and land-based expedition costs such as capital expenditures, crew payroll, land costs, fuel and food, and meaningfully reducing general and administrative expenses through reduced payroll and the elimination of all non-essential travel, office expenses and discretionary spending. The Company also accessed available capital under existing debt facilities and through the issuance of preferred stock. With the majority of operations resuming, operating costs are ramping back up, but given the continued uncertainty around COVID-19 and given that guest counts have not yet returned to traditional levels, the Company continues to minimize expenditures as appropriate.

Balance Sheet and Liquidity, Policy [Policy Text Block]

Balance Sheet and Liquidity

As of September 30, 2021, the Company had $155.6 million in unrestricted cash and $29.5 million in restricted cash primarily related to deposits on future travel originating from U.S. ports and credit card reserves. During August 2021, the Company received a $21.0 million grant under the Coronavirus Economic Relief for Transportation Services (“CERTS”) Act, which provided grants to eligible motorcoach, school bus, passenger vessel, and pilotage companies, see Note 4 — Financial Statement Details for additional information.

As of September 30, 2021, the Company had a total debt position of $561.8 million and was in compliance with all of its debt covenants.

During September 2021, the Company drew down $46.2 million under its second export credit agreement in conjunction with its final payment upon delivery of the National Geographic Resolution. In April 2021 the Company drew down $15.5 million under the second export credit agreement in conjunction with its fourth installment payment for the vessel.

During June 2021, the Company amended its export credit agreements to, among other things, extend the deferral of scheduled amortization payments of the first export credit facility through December 2021 in the aggregate amount of $15.7 million, extend the waiver of its total net leverage ratio covenant through March 31, 2022, increase the interest rate spreads of the export credit facilities by 50 basis points and annualize EBITDA used in its covenant calculation through December 31, 2022. The deferred principal payments will amortize quarterly over three years starting in March 2022. Certain other covenants continue to be more restrictive during the extended covenant waiver period.

During April 2021, the Company amended its term loan and revolving credit facilities to, among other things, extend the waiver of its total net leverage ratio covenant through March 31, 2022, annualize EBITDA used in its covenant calculation through December 31, 2022 and increase the interest rate spreads of the term loan, excluding the Main Street Loan, and the revolving credit facility by an additional 50 basis points. Certain other covenants continue to be more restrictive during the extended covenant waiver period.

Given the dynamic and unpredictable nature of the COVID-19 pandemic, the Company cannot reasonably estimate the potential impacts the pandemic will have on its financial condition, results of operations, cash flows, plans and growth for the foreseeable future. It is unknown when full travel restrictions and various remaining border closures will be lifted and what the demand for expedition travel will be once restrictions are no longer in place. Based on the actions taken to date by the Company, its planned and anticipated actions and its current forecast, the Company believes that it can meet its obligations for the next 12 months from November 2, 2021, the date of this Quarterly Report on Form 10-Q.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Adopted Accounting Pronouncements

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes. The amendments of this ASU are intended to simplify the accounting for income taxes by removing certain exceptions to the general principles in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending existing guidance. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The Company adopted this ASU as required, and it has not had, nor is it expected to have, a material impact to the Company’s financial statements.

Recent Accounting Pronouncements

In March 2020, the FASB issued ASU 2020-4, Reference Rate Reform (Topic 848)—Facilitation of the Effects of Reference Rate Reform on Financial Reporting. The guidance of this ASU is designed to provide relief from the accounting analysis and impacts that may otherwise be required for modifications to agreements (e.g., loans, debt securities, derivatives, borrowings) necessitated by reference rate reform. It also provides optional expedients to enable companies to continue to apply hedge accounting to certain hedging relationships impacted by reference rate reform. Application of the guidance is optional, is only available in certain situations, and is only available for companies to apply until December 31, 2022. The Company is currently reviewing its agreements impacted by the reference rate reform and does not expect this ASU to have a material impact to the Company’s financial statements.

In August 2020, the FASB issued ASU 2020-06, Debt–Debt with conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity's Own Equity (Subtopic 815-40)—Accounting for Convertible Instruments and Contracts in an Entity's Own Equity. The amendments in this ASU address issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. The amendments reduce the number of accounting models for convertible debt instruments and convertible preferred stock, and address convertible instruments with conversion features, as well as other items. This ASU is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. The Company will adopt this ASU as required and does not expect it to have a material impact to the Company’s financial statements.