Summary of Significant Accounting Policies (Details Textual)
$ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Mar. 31, 2018

USD ($)

Operatingsegments

Reportablesegments

$ / shares

Mar. 31, 2017

$ / shares

Dec. 31, 2017

USD ($)

Summary of Significant Accounting Policies (Textual)

Number of vessels, description

The Company operates two vessels year-round in the Galápagos National Park in Ecuador: the National Geographic Endeavour II with 95 berths and the National Geographic Islander with 47 berths. In order to operate these vessels within the park, the Company is required to have in its possession cupos (licenses) sufficient to cover the total available berths on each vessel.

Cash held in financial institutions

$ 6.7

$ 4.1

Credit card deposits

1.5

Unrecognized tax benefits

0.4

Additional tax expense

12.7

Contract liabilities

45.6

$ 40.3

$ 38.3

2015 Long-Term Incentive Plan [Member]

Summary of Significant Accounting Policies (Textual)

Issuance of maximum shares of common stock approved by Board of directors and stockholders | shares

2,500,000

Options to purchase an aggregate shares of common stock | shares

220,000

Weighted average exercise price per share | $ / shares

$ 9.63

Warrant [Member]

Summary of Significant Accounting Policies (Textual)

Anti-dilutive excluded potential common shares | shares

10,088,074

10,673,015

Warrants to purchase common stock at price | $ / shares

$ 11.50

Warrants expiration date

Jul. 08, 2020

Tradenames [Member]

Summary of Significant Accounting Policies (Textual)

Number of operating segments | Operatingsegments

Number of reportable segments | Reportablesegments

Intangibles, estimated useful life

15 years

Customer lists [Member]

Summary of Significant Accounting Policies (Textual)

Intangibles, estimated useful life

5 years

- Definition

Expiration date of warrants held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column A

Summary of Significant Accounting Policies (Details Textual) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) Operatingsegments Reportablesegments $ / shares shares	Mar. 31, 2017 $ / shares shares	Dec. 31, 2017 USD ($)
Summary of Significant Accounting Policies (Textual)
Number of vessels, description	The Company operates two vessels year-round in the Galápagos National Park in Ecuador: the National Geographic Endeavour II with 95 berths and the National Geographic Islander with 47 berths. In order to operate these vessels within the park, the Company is required to have in its possession cupos (licenses) sufficient to cover the total available berths on each vessel.
Cash held in financial institutions	$ 6.7		$ 4.1
Credit card deposits	1.5		1.5
Unrecognized tax benefits	0.4		0.4
Additional tax expense			12.7
Contract liabilities	45.6		$ 40.3
Revenues related to our contract liabilities	$ 38.3
2015 Long-Term Incentive Plan [Member]
Summary of Significant Accounting Policies (Textual)
Issuance of maximum shares of common stock approved by Board of directors and stockholders \| shares	2,500,000
Options to purchase an aggregate shares of common stock \| shares	220,000
Weighted average exercise price per share \| $ / shares	$ 9.63
Warrant [Member]
Summary of Significant Accounting Policies (Textual)
Anti-dilutive excluded potential common shares \| shares	10,088,074	10,673,015
Warrants to purchase common stock at price \| $ / shares	$ 11.50	$ 11.50
Warrants expiration date	Jul. 08, 2020	Jul. 08, 2020
Tradenames [Member]
Summary of Significant Accounting Policies (Textual)
Number of operating segments \| Operatingsegments	2
Number of reportable segments \| Reportablesegments	2
Intangibles, estimated useful life	15 years
Customer lists [Member]
Summary of Significant Accounting Policies (Textual)
Intangibles, estimated useful life	5 years