NCL (NCLC) 10-K 26 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 16, 2021	Jun. 30, 2020
Document And Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	333-128780
Entity Registrant Name	NCL CORPORATION LTD.
Entity Incorporation, State or Country Code	D0
Entity Tax Identification Number	20-0470163
Entity Address, Address Line One	7665 Corporate Center Drive
Entity Address, City or Town	Miami
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33126
City Area Code	305
Local Phone Number	436-4000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	Yes
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 0
Entity Common Stock Shares Outstanding		31,164,004
Entity Central Index Key	0001318742
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue
Total revenue	$ 1,279,908	$ 6,462,376	$ 6,055,126
Cruise operating expense
Payroll and related	521,301	924,157	881,606
Fuel	264,712	409,602	392,685
Total cruise operating expense	1,693,061	3,663,261	3,377,076
Other operating expense
Marketing, general and administrative	743,259	972,214	893,067
Depreciation and amortization	717,840	646,188	561,060
Impairment loss	1,607,797
Total other operating expense	3,068,896	1,618,402	1,454,127
Operating income (loss)	(3,482,049)	1,180,713	1,223,923
Non-operating income (expense)
Interest expense, net	(520,063)	(272,867)	(270,404)
Other income (expense), net	(984,501)	6,155	20,653
Total non-operating income (expense)	(1,504,564)	(266,712)	(249,751)
Net income (loss) before income taxes	(4,986,613)	914,001	974,172
Income tax benefit (expense)	(21,570)	27,205	(7,982)
Net income (loss)	(5,008,183)	941,206	966,190
Commissions transportation and other
Cruise operating expense
Total cruise operating expense	380,710	1,120,886	998,948
Passenger ticket
Revenue
Total revenue	867,110	4,517,393	4,259,815
Onboard and other
Revenue
Total revenue	412,798	1,944,983	1,795,311
Cruise operating expense
Total cruise operating expense	85,678	394,673	348,656
Food
Cruise operating expense
Total cruise operating expense	65,369	222,602	216,031
Other
Cruise operating expense
Total cruise operating expense	$ 375,291	$ 591,341	$ 539,150

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (5,008,183)	$ 941,206	$ 966,190
Other comprehensive income (loss):
Shipboard Retirement Plan	345	(1,930)	2,697
Cash flow hedges:
Net unrealized loss	(51,642)	(123,015)	(161,214)
Amount realized and reclassified into earnings	106,670	(8,898)	(30,096)
Total other comprehensive income (loss)	55,373	(133,843)	(188,613)
Total comprehensive income (loss)	$ (4,952,810)	$ 807,363	$ 777,577

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 3,299,340	$ 231,239
Accounts receivable, net	20,578	75,109
Inventories	82,381	95,427
Prepaid expenses and other assets	147,556	306,616
Total current assets	3,549,855	708,391
Property and equipment, net	13,411,226	13,135,337
Goodwill	98,134	1,388,931
Trade names	500,525	817,525
Other long-term assets	831,888	612,864
Total assets	18,391,628	16,663,048
Current liabilities:
Current portion of long-term debt	124,885	746,358
Accounts payable	83,136	100,777
Accrued expenses and other liabilities	596,717	782,665
Due to NCLH	37,790	35,044
Advance ticket sales	1,109,826	1,954,980
Total current liabilities	1,952,354	3,619,824
Long-term debt	10,128,754	6,055,335
Exchangeable notes	2,691,720
Other long-term liabilities	447,492	526,089
Total liabilities	15,220,320	10,201,248
Commitments and contingencies (Note 13)
Shareholders' equity:
Ordinary shares, $0.0012 par value; 40,000,000 shares authorized; 31,164,004 shares issued and outstanding at December 31, 2020 and December 31, 2019	37	37
Additional paid-in capital	5,721,725	4,061,330
Accumulated other comprehensive income (loss)	(241,830)	(297,203)
Retained earnings (deficit)	(2,308,624)	2,697,636
Total shareholders' equity	3,171,308	6,461,800
Total liabilities and shareholders' equity	$ 18,391,628	$ 16,663,048

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Ordinary shares, par value (in dollars per share)	$ 0.0012	$ 0.0012
Ordinary shares, authorized	40,000,000	40,000,000
Ordinary shares, issued	31,164,004	31,164,004
Ordinary shares, outstanding	31,164,004	31,164,004
Series A-1
Preferred stock, par value per share	$ 1,000
Preferred stock, shares authorized	2,000,000
Preferred shares, issued	0
Preferred shares, outstanding	0
Series A-2
Preferred stock, par value per share	$ 1,000
Preferred stock, shares authorized	2,000,000
Preferred shares, issued	0
Preferred shares, outstanding	0
Series A-3
Preferred stock, par value per share	$ 1,000
Preferred stock, shares authorized	1,000,000
Preferred shares, issued	0
Preferred shares, outstanding	0

Consolidated Statements of Cash

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 (loss)	$ (5,008,183)	$ 941,206	$ 966,190
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization expense	789,656	647,102	566,972
Impairment loss	1,607,797
Deferred income taxes, net	13,592	(25,861)	1,598
Loss on derivatives	930,113
Loss on extinguishment of debt	10,480	13,397	6,346
Provision for bad debts and inventory obsolescence	31,756	3,884	5,570
Gain on involuntary conversion of assets	(1,496)	(4,152)
Share-based compensation expense	111,297	95,055	115,983
Payment-in-kind interest premium	19,349
Net foreign currency adjustments	8,584	(1,934)	(5,537)
Changes in operating assets and liabilities:
Accounts receivable, net	30,797	(14,104)	(15,886)
Inventories	10,555	(6,155)	(9,052)
Prepaid expenses and other assets	(83,100)	(74,101)	(29,550)
Accounts payable	(21,419)	(58,635)	106,503
Accrued expenses and other liabilities	(193,666)	(25,751)	113,278
Advance ticket sales	(811,846)	347,376	262,603
Net cash provided by (used in) operating activities	(2,555,734)	1,837,327	2,085,018
Cash flows from investing activities
Additions to property and equipment, net	(946,545)	(1,637,170)	(1,566,796)
Cash received on settlement of derivatives		289	64,796
Cash paid on settlement of derivatives	(31,520)	(47,085)	(1,719)
Other	2,703	3,774	1,011
Net cash used in investing activities	(975,362)	(1,680,192)	(1,502,708)
Cash flows from financing activities
Repayments of long-term debt	(892,481)	(3,806,732)	(1,716,244)
Proceeds from long-term debt	6,075,090	4,122,297	1,904,865
Dividends		(341,000)	(637,500)
Due to NCLH, net	2,746	(15,350)	(11,338)
Contribution from NCLH	1,564,505	3,500	7,000
Net share settlement of restricted share units	(15,407)	(20,939)	(13,855)
Early redemption premium	(1,376)	(6,829)	(5,154)
Deferred financing fees	(133,880)	(23,262)	(118,422)
Net cash provided by (used in) financing activities	6,599,197	(88,315)	(590,648)
Net increase (decrease) in cash and cash equivalents	3,068,101	68,820	(8,338)
Cash and cash equivalents at beginning of period	231,239	162,419	170,757
Cash and cash equivalents at end of period	$ 3,299,340	$ 231,239	$ 162,419

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Ordinary Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Deficit)	Total
Balance at Dec. 31, 2017	$ 37	$ 3,874,586	$ 25,253	$ 1,768,728	$ 5,668,604
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation		115,983			115,983
Net share settlement of restricted share units		(13,855)			(13,855)
Contribution from NCLH		7,000			7,000
Other comprehensive income (loss), net | Accounting Standards Update 2017-12 [Member]			(188,601)		(188,601)
Other comprehensive income (loss), net					(188,613)
Dividends				(637,500)	(637,500)
Net income (loss)				966,190	966,190
Balance at Dec. 31, 2018	37	3,983,714	(163,360)	2,097,430	5,917,821
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative change in accounting policy | Accounting Standards Update 2017-12 [Member]			(12)	12
Share-based compensation		95,055			95,055
Net share settlement of restricted share units		(20,939)			(20,939)
Contribution from NCLH		3,500			3,500
Other comprehensive income (loss), net			(133,843)		(133,843)
Dividends				(341,000)	(341,000)
Net income (loss)				941,206	941,206
Balance at Dec. 31, 2019	37	4,061,330	(297,203)	2,697,636	6,461,800
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation		111,297			111,297
Net share settlement of restricted share units		(15,407)			(15,407)
Contribution from NCLH		1,564,505			1,564,505
Other comprehensive income (loss), net			55,373		55,373
Net income (loss)				(5,008,183)	(5,008,183)
Balance at Dec. 31, 2020	$ 37	$ 5,721,725	$ (241,830)	(2,308,624)	3,171,308
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative change in accounting policy | Accounting Standards Update 2016-13 [Member]				$ 1,923	$ 1,923

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	1. Description of Business We are a leading global cruise company which operates the Norwegian Cruise Line, Oceania Cruises and Regent Seven Seas Cruises brands. As of December 31, 2020, we had 28 ships with approximately 59,150 Berths and had orders for nine additional ships to be delivered through 2027. We have one Explorer Class Ship on order for delivery in 2023. We have two Allura Class Ships on order for delivery in 2023 and 2025.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Liquidity and Management’s Plan Due to the continued spread of COVID-19, growing travel restrictions and limited access to ports around the world, in March 2020, the Company implemented a voluntary suspension of all cruise voyages across its three brands. As of the date of this filing and through at least May 31, 2021, all cruise voyages remain suspended. Significant events affecting travel, including COVID-19, typically have an impact on demand for cruise vacations, with the full extent of the impact generally determined by the length of time the event influences travel decisions. We believe the ongoing effects of COVID-19 on our operations and global bookings have had, and will continue to have, a significant impact on our financial results and liquidity, and such negative impact may continue well beyond the containment of the pandemic. We continue to expect a gradual phased relaunch of our ships after the voyage suspension period, with our ships initially operating at reduced occupancy levels. The timing for bringing our ships back to service and the percentage of our fleet in service will depend on a number of factors including, but not limited to, the duration and extent of the COVID-19 pandemic, further resurgences and new variants of COVID-19, the availability, distribution, and efficacy of vaccines and therapeutics for COVID-19, our ability to comply with governmental regulations, port availability, travel restrictions, bans and advisories, and our ability to re-staff our ships and implement new health and safety protocols. The estimation of our future cash flow projections includes numerous assumptions that are subject to various risks and uncertainties. Upon the relaunch of cruise voyages, our principal assumptions for future cash flow projections include: ● Expected gradual phased relaunch at reduced occupancy levels; ● Forecasted cash collections primarily upon completion of future voyages and the payment of cash refunds for any further cancellations, in accordance with the terms of our credit card processing agreements (see Note 13 - “Commitments and Contingencies”); and ● Expected incremental expenses for resumption of cruise voyages, including the maintenance of and compliance with additional health and safety protocols. Due to the unknown duration and extent of the COVID-19 pandemic, travel restrictions, bans and advisories, uncertainties around our ability to comply with governmental regulations, the potential unavailability of ports and/or destinations, voyage cancellations and timing of redeployments, and a general impact on consumer sentiment regarding cruise travel, we cannot predict when we will relaunch voyages or when our full fleet will be back in service at historical occupancy levels. Until we are able to begin our phased relaunch, our projected liquidity requirements reflect our principal assumptions surrounding ongoing operating costs during the suspension of cruise voyages, as well as liquidity requirements for financing costs and necessary capital expenditures, and our ability to continue to implement cash conservation strategies, including, but not limited to: ● Moving our ships to minimum manning levels, which we expect would result in further reductions in crew payroll costs, fuel consumption, and maintenance costs; ● Further reductions in general operating expenses; and ● Further reductions in discretionary capital expenditures including cancellation or reduction in scope of certain Dry-docks. Subsequent to December 31, 2020 further actions, including debt principal payment deferrals and deferral of ship milestone payments, were taken to bolster our financial condition. See Note 8 – “Long-Term Debt” and Note 13 - “Commitments and Contingencies” disclosure for further information. We cannot make assurances that our assumptions used to estimate our liquidity requirements may not change because we have never experienced a complete cessation of our cruise voyages. Accordingly, the full effect of our suspension of cruise voyages on our financial performance and financial condition cannot be quantified at this time. We have made reasonable estimates and judgments of the impact of COVID-19 within our financial statements and there may be material changes to those estimates in future periods. We expect to report a net loss for at least the quarter ending March 31, 2021, and likely expect to report a net loss until we are able to resume voyages, including for the year ending December 31, 2021. Based on these actions and assumptions regarding the impact of COVID-19, and considering our available liquidity including cash and cash equivalents of $3.3 billion at December 31, 2020, we have concluded that after implementing the above cash conservation strategies, we have sufficient liquidity to satisfy our obligations for at least the next twelve months even in the event we do not resume cruise voyages during that period. Subsequent to the liquidity assessment period (twelve months from the issuance of these financial statements), the Company will require additional liquidity to meet ongoing obligations, including debt amortization payments and ship milestone payments, of approximately $560 million that are due in April 2022, in order to maintain its minimum liquidity covenant requirements. The Company plans to take additional steps following the issuance of these financial statements to increase its liquidity, which may include additional debt and/or equity financing and potential further renegotiations of its debt amortization payments, newbuild payments and covenants. The extent of these actions to increase the Company’s liquidity will be dependent in part on the timing of the resumption of cruise voyages, which is uncertain. There can be no assurances that the Company will be successful in generating the additional liquidity necessary to meet its obligations beyond twelve months from the issuance of these financial statements on terms acceptable to the Company or at all. If the Company is unable to maintain or renegotiate its minimum liquidity covenant requirements, it could have a significant adverse effect on the Company’s business, financial condition and operating results. Basis of Presentation Our consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America and contain all normal recurring adjustments necessary for a fair presentation of the results for the periods presented. Estimates are required for the preparation of consolidated financial statements in accordance with generally accepted accounting principles and actual results could differ from these estimates. All significant intercompany accounts and transactions are eliminated in consolidation. Cash and Cash Equivalents Cash and cash equivalents are stated at cost and include cash and investments with original maturities of three months or less at acquisition and also include amounts due from credit card processors that are not subject to holdbacks. Accounts Receivable, Net Accounts receivable are shown net of an allowance for credit losses of $35.4 million and $10.6 million as of December 31, 2020 and 2019, respectively. Inventories Inventories mainly consist of provisions, supplies and fuel and are carried at the lower of cost or net realizable value using the first-in, first-out method of accounting. Advertising Costs Advertising costs are expensed as incurred except for those that result in tangible assets, including brochures, which are treated as prepaid expenses and charged to expense as consumed. Advertising costs of $0.9 million and $5.9 million as of December 31, 2020 and 2019, respectively, are included in prepaid expenses and other assets. Expenses related to advertising costs totaled $216.5 million, $400.6 million and $327.3 million for the years ended December 31, 2020, 2019 and 2018, respectively. Property and Equipment, Net Property and equipment are recorded at cost. Ship improvement costs that we believe add value to our ships are capitalized to the ship and depreciated over the shorter of the improvements’ estimated useful lives or the remaining useful life of the ship while costs of repairs and maintenance, including Dry-dock costs, are charged to expense as incurred. During ship construction, certain interest is capitalized as a cost of the ship. Gains or losses on the sale of property and equipment are recorded as a component of operating income (expense) in our consolidated statements of operations. The useful lives of ship improvements are estimated based on the economic lives of the new components. In addition, to determine the useful lives of the ship or ship components, we consider the impact of the historical useful lives of similar assets, manufacturer recommended lives and anticipated changes in technological conditions. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, after a 15% reduction for the estimated residual values of ships as follows: ​ ​ ​ ​ ​ Useful Life Ships 30 years Computer hardware and software 3 Other property and equipment 3 Leasehold improvements Shorter of lease term or asset life Ship improvements Shorter of asset life or life of the ship ​ Long-lived assets are reviewed for impairment, based on estimated future undiscounted cash flows, whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Assets are grouped and evaluated at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other groups of assets. For ship impairment analyses, the lowest level for which identifiable cash flows are largely independent of other assets and liabilities is each individual ship. We consider historical performance and future estimated results in our evaluation of potential impairment and then compare the carrying amount of the asset to the estimated future cash flows expected to result from the use of the asset. If the carrying amount of the asset exceeds estimated expected undiscounted future cash flows, we measure the amount of the impairment by comparing the carrying amount of the asset to its estimated fair value. We estimate fair value based on the best information available utilizing estimates, judgments and projections as necessary. Our estimate of fair value is generally measured by discounting expected future cash flows at discount rates commensurate with the associated risk. Goodwill and Trade Names Goodwill represents the excess of cost over the estimated fair value of net assets acquired. Goodwill and other indefinite-lived assets, principally trade names, are reviewed for impairment on December 31 or earlier if there is an event or change in circumstances that would indicate that the carrying value of these assets may not be fully recoverable. We use the Step 0 Test which allows us to first assess qualitative factors to determine whether it is more likely than not (i.e., more than 50%) that the estimated fair value of a reporting unit is less than its carrying value. For trade names we also provide a qualitative assessment to determine if there is any indication of impairment. In order to make this evaluation, we consider the following circumstances as well as others: ● Changes in general macroeconomic conditions such as a deterioration in general economic conditions; limitations on accessing capital; fluctuations in foreign exchange rates; or other developments in equity and credit markets; ● Changes in industry and market conditions such as a deterioration in the environment in which an entity operates; an increased competitive environment; a decline in market-dependent multiples or metrics (in both absolute terms and relative to peers); a change in the market for an entity’s products or services; or a regulatory or political development; ● Changes in cost factors that have a negative effect on earnings and cash flows; ● Decline in overall financial performance (for both actual and expected performance); ● Entity and reporting unit specific events such as changes in management, key personnel, strategy, or customers; litigation; or a change in the composition or carrying amount of net assets; and ● Decline in share price (in both absolute terms and relative to peers). We also may conduct a quantitative assessment comparing the estimated fair value of each reporting unit to its carrying value, including goodwill. This is called the Step 1 Test which uses discounted future cash flows and other market data to determine the estimated fair value of the reporting units. Our discounted cash flow valuation reflects our principal assumptions of 1) forecasted future operating results and growth rates, which have been prepared under multiple scenarios and are probability weighted, 2) forecasted capital expenditures for fleet growth and ship improvements and 3) a weighted average cost of capital of market participants. Historically, our Step 1 Test consisted of a combined approach using discounted future cash flows and market multiples to determine the estimated fair value of the reporting units. However, beginning with the Step 1 Test performed as of March 31, 2020 as a result of triggering events, the market multiples were used solely as a corroboratory approach given the impact of COVID-19 on the current year’s results, as of the valuation date, as well as prospective results including the lack of any guidance provided, which were not available for our peers. We believe that this approach is the most representative method to estimate fair value as it utilizes expectations of long-term growth as well as current market conditions. For the trade names, we use the relief from royalty method, which uses the same forecasts and discount rates from the discounted cash flow valuation in the goodwill assessment along with a trade name royalty rate assumption. ​ We have concluded that our business has three reporting units. Each brand, Oceania Cruises, Regent Seven Seas and Norwegian, constitutes a business for which discrete financial information is available and management regularly reviews the operating results and, therefore, each brand is considered an operating segment. During the year ended December 31, 2020, we recognized a goodwill impairment loss of $1.3 billion based on the impairment test performed as of March 31, 2020. See Note 4 – “Goodwill and Intangible Assets” for additional information. As of December 31, 2020, there was $98.1 million of goodwill remaining for the Regent Seven Seas reporting unit. We also recognized an impairment loss for our Oceania Cruises and Regent Seven Seas Cruises trade names in an aggregate amount of $317.0 million based on the March 31, 2020 impairment test, with $500.5 million remaining as of December 31, 2020. For our 2020 annual goodwill and trade name impairment evaluations, we elected to perform quantitative testing. Based on the results of the Step 1 Tests at December 31, 2020, we determined there was no further impairment of goodwill because the estimated fair value of the Regent Seven Seas reporting unit substantially exceeded the carrying value. We also determined there was no impairment to our trade names. We believe that we have made reasonable estimates and judgments. However, a change in our estimated future operating cash flows may result in a decline in estimated fair value in future periods, which may result in a need to recognize additional impairment charges. Revenue and Expense Recognition Deposits on advance ticket sales are deferred when received and are subsequently recognized as revenue ratably during the voyage sailing days as services are rendered over time on the ship. Cancellation fees are recognized in passenger ticket revenue in the month of the cancellation. Goods and services associated with onboard revenue are generally provided at a point in time and revenue is recognized when the performance obligation is satisfied. A receivable is recognized for onboard goods and services rendered when the voyage is not completed before the end of the period. All associated direct costs of a voyage are recognized as incurred in cruise operating expenses. Disaggregation of Revenue Revenue and cash flows are affected by economic factors in various geographical regions. Revenues by destination consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 ​ 2018 North America ​ $ 960,258 ​ $ 3,807,576 ​ $ 3,543,282 Europe ​ 27,602 ​ 1,666,751 ​ 1,462,698 Asia-Pacific ​ 152,976 ​ 500,842 ​ 721,404 Other ​ 139,072 ​ 487,207 ​ 327,742 Total revenue ​ $ 1,279,908 ​ $ 6,462,376 ​ $ 6,055,126 ​ Segment Reporting We have concluded that our business has a single reportable segment. Each brand, Norwegian, Oceania Cruises and Regent, constitutes a business for which discrete financial information is available and management regularly reviews the brand level operating results and, therefore, each brand is considered an operating segment. Our operating segments have similar economic and qualitative characteristics, including similar long-term margins and similar products and services; therefore, we aggregate all of the operating segments into one reportable segment. Although we sell cruises on an international basis, our passenger ticket revenue is primarily attributed to U.S.-sourced guests who make reservations in the U.S. Revenue attributable to U.S.-sourced guests was 83%, 81% and 77% for the years ended December 31, 2020, 2019 and 2018, respectively. No other individual country’s revenues exceeded 10% in any of our last three years. Substantially all of our long-lived assets are located outside of the U.S. and consist primarily of our ships. We had 19 ships with Bahamas registry with a carrying value of $9.9 billion as of December 31, 2020 and $10.2 billion as of December 31, 2019. We had eight ships with Marshall Island registry with a carrying value of $2.4 billion as of December 31, 2020 and seven ships with Marshall Island registry with a carrying value of $1.9 billion as of December 31, 2019. We also had one ship with U.S. registry with a carrying value of $0.3 billion as of December 31, 2020 and 2019. Debt Issuance Costs Debt issuance costs related to a recognized debt liability are presented in the consolidated balance sheets as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. For line of credit arrangements and for those debt facilities not fully drawn we defer and present debt issuance costs as an asset. These deferred issuance costs are amortized over the life of the loan. The amortization of deferred financing fees is included in depreciation and amortization expense in the consolidated statements of cash flows; however, for purposes of the consolidated statements of operations it is included in interest expense, net. Payment-in-Kind Interest Payment-in-kind interest is recognized at the stated rate. On the contractual interest payment date, the related par value is recognized at its fair value with any difference between the carrying amount of the accrued interest and the fair value of the new debt recognized as an adjustment in interest expense, net. The amount of fair value that is attributable to a debt conversion option is bifurcated and recognized within exchangeable notes. In December 2020, we recognized a $19.3 million premium for payment-in-kind interest. Foreign Currency The majority of our transactions are settled in U.S. dollars. Gains or losses resulting from transactions denominated in other currencies are recognized in other income (expense), net at each balance sheet date. We recognized a loss of $15.9 million, a loss of $7.0 million and a gain of $19.8 million for the years ended December 31, 2020, 2019 and 2018, respectively. Derivative Instruments and Hedging Activity We enter into derivative contracts to reduce our exposure to fluctuations in foreign currency exchange rates, interest rates and fuel prices. The criteria used to determine whether a transaction qualifies for hedge accounting treatment includes the correlation between fluctuations in the fair value of the hedged item and the fair value of the related derivative instrument and its effectiveness as a hedge. As the derivative is marked to fair value, we elected an accounting policy to net the fair value of our derivatives when a master netting arrangement exists with our counterparties. A derivative instrument that hedges a forecasted transaction or the variability of cash flows related to a recognized asset or liability may be designated as a cash flow hedge. Changes in fair value of derivative instruments that are designated as cash flow hedges are recorded as a component of accumulated other comprehensive income (loss) until the underlying hedged transactions are recognized in earnings. To the extent that an instrument is not effective as a hedge or is no longer probable of occurring, gains and losses are recognized in other income (expense), net in our consolidated statements of operations. Realized gains and losses related to our effective fuel hedges are recognized in fuel expense. For presentation in our consolidated statements of cash flows, we have elected to classify the cash flows from our cash flow hedges in the same category as the cash flows from the items being hedged. Concentrations of Credit Risk We monitor concentrations of credit risk associated with financial and other institutions with which we conduct significant business. Credit risk, including but not limited to counterparty non-performance under derivative instruments, our Revolving Loan Facility and new ship progress payment guarantees, is not considered significant, as we primarily conduct business with large, well-established financial institutions and insurance companies that we have well-established relationships with and that have credit risks acceptable to us or the credit risk is spread out among a large number of creditors. We do not anticipate non-performance by any of our significant counterparties. Insurance We use a combination of insurance and self-insurance for a number of risks including claims related to crew and guests, hull and machinery, war risk, workers’ compensation, property damage, employee healthcare and general liability. Liabilities associated with certain of these risks, including crew and passenger claims, are estimated actuarially based upon known facts, historical trends and a reasonable estimate of future expenses. While we believe these accruals are adequate, the ultimate losses incurred may differ from those recorded. Income Taxes Deferred tax assets and liabilities are calculated in accordance with the liability method. Deferred taxes are recorded using the currently enacted tax rates that apply in the periods that the differences are expected to reverse. Deferred taxes are not discounted. We provide a valuation allowance on deferred tax assets when it is more likely than not that such assets will not be realized. With respect to acquired deferred tax assets, changes within the measurement period that result from new information about facts and circumstances that existed at the acquisition date shall be recognized through a corresponding adjustment to goodwill. Subsequent to the measurement period, all other changes shall be reported as a reduction or increase to income tax expense in our consolidated statements of operations. Share-Based Compensation We recognize expense for our share-based compensation awards using a fair-value-based method. Share-based compensation expense is recognized over the requisite service period for awards that are based on a service period and not contingent upon any future performance. We refer you to Note 11 – “Employee Benefits and Share-Based Compensation.” Recently Issued Accounting Guidance In August 2020, the Financial Accounting Standards Board (“FASB”) issued ASU No. 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 feature on the Private Exchangeable Notes (as defined and discussed in Note 8 – “Long-Term Debt”) which is included in additional paid-in-capital will be reclassified to long-term debt. Any related interest which has been recognized will be adjusted through retained earnings. Additional disclosures will be added as necessary. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”), which provided guidance to alleviate the burden in accounting for reference rate reform by allowing certain expedients and exceptions in applying GAAP to contracts, hedging relationships and other transactions impacted by reference rate reform. The provisions apply only to those transactions that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform. Adoption of the provisions of ASU 2020-04 are optional and are effective from March 12, 2020 through December 31, 2022. We are currently evaluating the impact of ASU 2020-04 on our consolidated financial statements.

Revenue and Expense from Contra

Revenue and Expense from Contracts with Customers	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenue and Expense from Contracts with Customers	3. Revenue and Expense from Contracts with Customers Nature of Goods and Services We offer our guests a multitude of cruise fare options when booking a cruise. Our cruise ticket prices generally include cruise fare and a wide variety of onboard activities and amenities, meals, entertainment and port fees and taxes. In some instances, cruise ticket prices include round-trip airfare to and from the port of embarkation, complimentary beverages, unlimited shore excursions, free internet, pre-cruise hotel packages, and on some of the exotic itineraries, pre- or post-land packages. Prices vary depending on the particular cruise itinerary, stateroom category selected and the time of year that the voyage takes place. Passenger ticket revenue also includes full ship charters as well as port fees and taxes. During the voyage, we generate onboard and other revenue for additional products and services which are not included in the cruise fare, including casino operations, certain food and beverage, gift shop purchases, spa services, photo services, Wi-Fi services and other similar items. Food and beverage, casino operations, photo services and shore excursions are generally managed directly by us while retail shops, spa services, art auctions and internet services may be managed through contracts with third-party concessionaires. These contracts generally entitle us to a percentage of the gross sales derived from these concessions, which is recognized on a net basis. While some onboard goods and services may be prepaid prior to the voyage, we utilize point-of-sale systems for discrete purchases made onboard. Certain of our product offerings are bundled and we allocate the value of the bundled goods and services between passenger ticket revenue and onboard and other revenue based upon the relative standalone selling prices of those goods and services. Timing of Satisfaction of Performance Obligations and Significant Payment Terms The payment terms and cancellation policies vary by brand, stateroom category, length of voyage, and country of purchase. A deposit for a future booking is required at or soon after the time of booking. Final payment is generally due between 120 days and 180 days before the voyage; however, the Company has modified its final payment schedule for all voyages on Regent Seven Seas Cruises through July 31, 2021 and for all voyages on Oceania Cruises and the majority of bookings for voyages on Norwegian Cruise Line through October 31, 2021 which requires payment 60 days prior to embarkation. Deposits on advance ticket sales are deferred when received and include amounts that are refundable. Deferred amounts are subsequently recognized as revenue ratably during the voyage sailing days as services are rendered over time on the ship. Deposits are generally cancellable and refundable prior to sailing, but may be subject to penalties, depending on the timing of cancellation. Historically, the inception of substantive cancellation penalties generally coincided with the dates that final payment is due, and penalties generally increased as the voyage sail date approaches. In 2020, the Company’s brands launched new cancellation policies to permit its guests to cancel cruises booked within certain windows for specified time periods which are not part of the Company’s temporary suspension of voyages up to 15 days prior to departure. Cancellation fees are recognized in passenger ticket revenue in the month of the cancellation. Goods and services associated with onboard revenue are generally provided at a point in time and revenue is recognized when the performance obligation is satisfied. Onboard goods and services rendered may be paid at disembarkation. A receivable is recognized for onboard goods and services rendered when the voyage is not completed before the end of the period. Cruises that are reserved under full ship charter agreements are subject to the payment terms of the specific agreement and may be either cancelable or non-cancelable. Deposits received on charter voyages are deferred when received and included in advance ticket sales. Deferred amounts are subsequently recognized as revenue ratably over the voyage sailing dates. Contract Balances Receivables from customers are included within accounts receivables, net. As of December 31, 2020 and 2019, our receivables from customers were $1.0 million and $15.3 million, respectively. Contract liabilities represent the Company’s obligation to transfer goods and services to a customer. A customer deposit held for a future cruise is generally considered a contract liability only when final payment is both due and paid by the customer and is usually recognized in earnings within 180 days of becoming a contract. Other deposits held and included within advance ticket sales or other long-term liabilities are not considered contract liabilities as they are largely cancelable and refundable. Additionally, future cruise credits are not considered contract liabilities. Our contract liabilities are included within advance ticket sales. As of December 31, 2020, our contract liabilities were $23.1 million. Of the amounts included within advance ticket sales, the vast majority of deposits held was refundable in accordance with our cancellation policies and it is uncertain to what extent guests may request refunds. Refunds payable to guests are included in accounts payable. As of December 31, 2019, our contract liabilities were $1.4 billion. Approximately $0.9 billion of the December 31, 2019 contract liability balance has been recognized in revenue for the year ended December 31, 2020. The revenue recognized in the years ended December 31, 2019 and 2018 that was included in contract liabilities as of the beginning of each respective period was $1.2 billion and $1.0 billion, respectively. Our revenue is seasonal based on demand for cruises, which has historically been strongest during the Northern Hemisphere’s summer months; however, our cruise voyages were completely suspended during the last nine months of 2020 due to the COVID-19 pandemic and such suspension has been extended through May 31, 2021. As a result of COVID-19, including the issuance of future cruise credits for suspended voyages in 2020, the suspension of voyages through May 31, 2021 and modifications to our payment and cancellation policies, there has been a significant decline in the contract liability balance as of December 31, 2020. Practical Expedients and Exemptions We do not disclose information about remaining performance obligations that have original expected durations of one year or less. We recognize revenue in an amount that corresponds directly with the value to the customer of our performance completed to date. Variable consideration, which will be determined based on a future rate and passenger count, is excluded from the disclosure and these amounts are not material. These variable non-disclosed contractual amounts relate to non-cancelable charter agreements and a leasing arrangement with a certain port, both of which are long-term in nature. Amounts that are fixed in nature due to the application of minimum guarantees are also not material and are not disclosed. Contract Costs Management generally expects that incremental commissions and credit card fees paid as a result of obtaining ticket contracts are recoverable; therefore, we recognize these amounts as assets when they are paid prior to the voyage. Costs of air tickets, port taxes and other fees that fulfill future performance obligations are also considered recoverable and are recorded as assets. Costs incurred to obtain customers were $41.3 million and $143.5 million as of December 31, 2020 and 2019, respectively. Costs to fulfill contracts with customers were $5.5 million and $49.7 million as of December 31, 2020 and 2019, respectively. Both costs to obtain and fulfill contracts with customers are recognized within prepaid expenses and other assets. Incremental commissions, credit card fees, air ticket costs, and port taxes and fees are recognized ratably over the voyage sailing dates, concurrent with associated revenue, and are primarily in commissions, transportation and other expense. For cruise vacations that had been cancelled by us due to COVID-19, approximately $171.5 million in costs to obtain these contracts, consisting of protected commissions, including those paid to employees, and credit card fees, were recognized in earnings during the year ended December 31, 2020.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	4. Goodwill and Intangible Assets We evaluate goodwill and trade names for impairment annually or more frequently when an event occurs or circumstances change that indicates the carrying value of a reporting unit may not be recoverable. In March 2020, the Company announced a voluntary suspension of all cruise voyages for its three brands, which has subsequently been extended through May 31, 2021. Due to the temporary suspension of voyages and decline in our stock price, we performed interim goodwill and trade name impairment tests as of March 31, 2020. We refer you to Note 10 – “Fair Value Measurements and Derivatives” for information on our valuation assumptions. The changes in the carrying amount of goodwill for each reporting unit for the year ended December 31, 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reporting Unit ​ ​ ​ ​ ​ Norwegian ​ ​ ​ Regent ​ ​ ​ ​ Cruise ​ Oceania ​ Seven Seas ​ Total ​ ​ Line Cruises Cruises Goodwill Balance, December 31, 2019 $ 403,805 ​ $ 523,026 ​ $ 462,100 ​ $ 1,388,931 Impairment loss ​ (403,805) ​ (523,026) ​ (363,966) ​ (1,290,797) Balance, December 31, 2020 ​ $ — ​ $ — ​ $ 98,134 ​ $ 98,134 ​ We also impaired our trade names for Oceania Cruises and Regent Seven Seas Cruises by $170.0 million and $147.0 million, respectively. Following these impairments, the carrying value of our trade names was $500.5 million, which consists of $207.5 million for Norwegian Cruise Line, $140.0 million for Oceania Cruises and $153.0 million for Regent Seven Seas Cruises. The gross carrying amounts of intangible assets included within other long-term assets, the related accumulated amortization, the net carrying amounts and the weighted-average amortization periods of the Company’s intangible assets are listed in the following tables (in thousands, except amortization period): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ Gross Carrying ​ Accumulated ​ Net Carrying ​ Amortization ​ ​ Amount ​ Amortization ​ Amount Period (Years) Customer relationships ​ $ 120,000 ​ $ (120,000) ​ $ — 6.0 License ​ 750 ​ (406) ​ 344 10.0 Total intangible assets subject to amortization ​ $ 120,750 ​ $ (120,406) ​ $ 344 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ Gross Carrying ​ Accumulated ​ Net Carrying ​ Amortization ​ ​ Amount ​ Amortization ​ Amount Period (Years) Customer relationships ​ $ 120,000 ​ $ (110,169) ​ $ 9,831 6.0 Licenses ​ 750 ​ (331) ​ 419 10.0 Total intangible assets subject to amortization ​ $ 120,750 ​ $ (110,500) ​ $ 10,250 ​ The aggregate amortization expense is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 ​ 2018 Amortization expense ​ $ 9,906 ​ $ 18,488 ​ $ 26,163 ​ The following table sets forth the Company’s estimated aggregate amortization expense for each of the five years below (in thousands): ​ ​ ​ ​ ​ ​ Amortization Year ended December 31, ​ Expense 2021 ​ $ 75 2022 ​ ​ 75 2023 ​ ​ 75 2024 ​ ​ 75 2025 ​ ​ 44 ​

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	5 . Leases On January 1, 2019, we adopted ASU No. 2016-02, Leases (“Topic 842”). Topic 842 supersedes the lease accounting requirements in Accounting Standards Codification (“ASC”) 840—Leases. In August 2018, the FASB issued ASU 2018-11, Targeted Improvements to Topic 842, which included an option to apply the new leases standard at the adoption date using a modified retrospective approach, which the Company elected. Nature of Leases We have finance leases for certain ship equipment and a corporate office. We have operating leases for port facilities, corporate offices, warehouses, and certain equipment. Many of our leases include both lease and non-lease components. We have adopted the practical expedient which allows us to combine lease and non-lease components by class of asset. We have applied this expedient for office leases, port facilities, and certain equipment. The components of lease expense and revenue were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ Year Ended ​ December 31, 2020 December 31, 2019 Operating lease expense $ 19,406 $ 31,596 Variable lease expense ​ 9,705 ​ 14,284 Short-term lease expense ​ 11,076 ​ 50,832 Finance lease cost: ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ 1,924 ​ 1,765 Interest on lease liabilities ​ 1,072 ​ 1,239 Operating lease revenue ​ 173 ​ 446 Sublease income ​ 1,616 ​ 1,615 ​ Total expense under non-cancelable operating leases, primarily for offices, motor vehicles and office equipment was $16.9 million for the year ended December 31, 2018 under the previous lease accounting standard (ASC 840). ​ Lease balances were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance Sheet location December 31, 2020 December 31, 2019 Operating leases ​ ​ ​ ​ ​ ​ ​ Right-of-use assets Other long-term assets $ 209,037 $ 236,604 Current operating lease liabilities Accrued expenses and other liabilities ​ 17,700 ​ 39,126 Non-current operating lease liabilities Other long-term liabilities ​ 185,414 ​ 207,243 ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance leases ​ ​ ​ ​ ​ ​ ​ ​ Right-of-use assets Property and equipment, net ​ 11,948 ​ 13,873 Current finance lease liabilities Current portion of long-term debt ​ 5,143 ​ 6,419 Non-current finance lease liabilities Long-term debt ​ 4,648 ​ 8,812 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental cash flow and non-cash information related to leases was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended Year Ended ​ December 31, 2020 December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ Operating cash outflows from operating leases $ 70,555 $ 75,539 Operating cash outflows from finance leases ​ 898 ​ 1,051 Financing cash outflows from finance leases ​ 4,078 ​ 2,826 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease obligations: ​ ​ ​ ​ ​ Operating leases ​ 823 ​ 24,834 Finance leases ​ ​ — ​ 705 ​ Other supplemental information related to leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ Year Ended ​ ​ December 31, 2020 December 31, 2019 ​ Weighted average remaining lease term (years) - operating leases ​ 7.36 ​ 8.30 ​ Weighted average remaining lease term (years) - finance leases ​ 2.89 ​ ​ 3.65 ​ Weighted average discount rate - operating leases ​ ​ 3.96 % ​ 3.76 % Weighted average discount rate - finance leases ​ ​ 7.75 % ​ 7.47 % ​ As of December 31, 2020, maturities of lease liabilities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Finance ​ leases leases 2021 $ 27,371 ​ $ 4,891 ​ 2022 ​ ​ 32,105 ​ 3,910 ​ 2023 ​ ​ 31,866 ​ 683 ​ 2024 ​ ​ 32,065 ​ 630 ​ 2025 ​ ​ 31,827 ​ 544 ​ Thereafter ​ ​ 80,951 ​ 38 ​ Total ​ ​ 236,185 ​ ​ 10,696 ​ Less: Present value discount ​ ​ (33,071) ​ ​ (905) ​ Present value of lease liabilities $ 203,114 ​ $ 9,791 ​ ​ Significant Assumptions and Judgments in Applying Topic 842 and Practical Expedients Elected Our leases contain both fixed and variable payments. Fixed payments and variable lease payments that depend on a rate or index are included in the calculation of the right-of-use asset. Other variable payments are excluded from the calculation unless there is an unavoidable fixed minimum cost related to those payments such as a minimum annual guarantee. Our lease assets are amortized on a straight-line basis except for our rights to use port facilities. The expenses related to port facilities are amortized based on passenger counts as this basis represents the pattern in which the economic benefit is derived from the right to use the underlying asset. For non-consecutive lease terms, which relate to our rights to use certain port facilities, the term of the lease is based on the number of days on which we have the right to use a specified asset. We have adopted the practical expedient to exclude leases with terms of less than one year from being included on the balance sheet. Lease expense for agreements that are short-term are disclosed below and include both fixed and variable payments. Certain leases include one or more options to extend or terminate and are primarily in five-year increments. Lease extensions and terminations, including auto-renewing lease terms, were only included in the calculation of the right-of-use asset to the extent that the right to renew or terminate was at the option of the lessor only or where there was a more than insignificant penalty for termination. As our leases do not have a readily determinable implicit rate, we used our weighted average cost of debt to determine the net present value of the lease payments at the adoption date. Our weighted average cost of debt is similar to the incremental borrowing rate we would have obtained if we had borrowed collateralized debt over the lease term to purchase the asset, and the rate was adjusted for longer term leases. We have also adopted the practical expedient which allows us, by class of asset, to not separate lease and non-lease components when we are the lessor in the underlying transaction, the transactions would otherwise be accounted for under ASC 606–Revenue Recognition and the non-lease components are the predominant components of the agreements. We have applied this practical expedient to transactions with cruise passengers and concession service providers related to the use of our ships. We refer you to Note 3 – “Revenue and Expense from Contracts with Customers.” Impact of COVID-19 In April 2020, the FASB issued interpretive guidance relating to the accounting for lease concessions provided as a result of COVID-19. In this guidance, entities can elect not to apply lease modification accounting with respect to such lease concessions and instead, treat the concession as if it was a part of the existing contract. The Company has elected to not evaluate leases under the lease modification accounting framework for concessions that result from effects of the COVID-19 pandemic. In relation to our rights to use port facilities, we have elected the approach consistent with resolving a contingency, which allows us to remeasure the lease liability and recognize the amount of change in the lease liability as an adjustment to the carrying amount of the associated right-of-use asset. As of December 31, 2020, our port facilities were remeasured with a downward adjustment of $17.7 million to both other long-term assets and accrued expenses and other liabilities. Another $2.1 million was reclassified from accrued expenses and other liabilities to other long-term assets as a result of contractual extensions. As the full amount of the concession will not be determinable until the force majeure period under the related arrangements has ended, further remeasurements will be required. During the contingency period, we are recognizing lease expense for these port facilities as incurred. ​ Leases That Have Not Yet Commenced ​ We have multiple agreements that have been executed where the lease term has not commenced as of December 31, 2020. These are primarily related to our rights to use certain port facilities which were under construction during 2020. Although we may have provided design input, construction management services, or advances related to these assets, we have determined that we did not control these assets during the period of construction. As of December 31, 2020, these agreements are under force majeure and are now not expected to commence until the second or third quarter of 2021. These port facilities have undiscounted minimum annual guarantees of approximately $1.2 billion of passenger fees.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Accumulated Other Comprehensive Income (Loss)	6. Accumulated Other Comprehensive Income (Loss) Accumulated other comprehensive income (loss) was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ ​ ​ ​ Change ​ ​ Accumulated ​ Change ​ Related to ​ ​ Other ​ Related to ​ Shipboard ​ Comprehensive Cash Flow ​ Retirement ​ ​ ​ Income (Loss) ​ Hedges ​ Plan ​ Accumulated other comprehensive income (loss) at beginning of period ​ $ (297,203) ​ $ (290,009) $ (7,194) Current period other comprehensive loss before reclassifications ​ (51,704) ​ (51,642) (62) Amounts reclassified into earnings ​ 107,077 ​ 106,670 (1) 407 (2) Accumulated other comprehensive income (loss) at end of period ​ $ (241,830) ​ $ (234,981) (3) $ (6,849) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ ​ ​ ​ ​ Change ​ ​ Accumulated ​ Change ​ Related to ​ ​ Other ​ Related to ​ Shipboard ​ ​ Comprehensive ​ Cash Flow ​ Retirement ​ ​ Income (Loss) ​ Hedges ​ Plan ​ Accumulated other comprehensive income (loss) at beginning of period ​ $ (163,360) ​ $ (158,096) ​ $ (5,264) ​ Current period other comprehensive loss before reclassifications ​ (125,323) ​ (123,015) (2,308) ​ Amounts reclassified into earnings ​ (8,520) ​ (8,898) (1) 378 (2) Accumulated other comprehensive income (loss) at end of period ​ $ (297,203) ​ $ (290,009) $ (7,194) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2018 ​ ​ ​ ​ ​ Change ​ ​ Accumulated ​ Change ​ Related to ​ ​ Other ​ Related to ​ Shipboard ​ ​ Comprehensive ​ Cash Flow ​ Retirement ​ ​ Income (Loss) ​ Hedges ​ ​ Plan ​ Accumulated other comprehensive income (loss) at beginning of period ​ $ 25,253 ​ $ 33,214 $ (7,961) Current period other comprehensive income (loss) before reclassifications ​ (158,943) ​ (161,214) 2,271 Amounts reclassified into earnings ​ (29,670) ​ (30,096) (1) 426 (2) Accumulated other comprehensive income (loss) at end of period ​ $ (163,360) ​ $ (158,096) $ (5,264) (1) We refer you to Note 10 – “Fair Value Measurements and Derivatives” in these notes to consolidated financial statements for the affected line items in the consolidated statements of operations. (2) Amortization of prior-service cost and actuarial loss reclassified to other income (expense), net. (3) Includes $62.7 million of loss expected to be reclassified into earnings in the next 12 months.

Property and Equipment, net

Property and Equipment, net	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment, Net [Abstract]
Property and Equipment, net	7. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Ships ​ $ 14,528,133 ​ $ 14,154,578 Ships improvements ​ 2,109,015 ​ 1,865,272 Ships under construction ​ 376,062 ​ 387,749 Land and land improvements ​ 58,370 ​ 38,375 Other ​ 765,739 ​ 672,975 ​ ​ 17,837,319 ​ 17,118,949 Less: accumulated depreciation ​ (4,426,093) ​ (3,983,612) Property and equipment, net ​ $ 13,411,226 ​ $ 13,135,337 ​ The increase in ships was primarily due to the addition of Seven Seas Splendor. The Company capitalized approximately $341.5 million of costs associated with ship improvements. In 2020, one ship had significant improvements that extended the weighted average useful life of the vessel. Accordingly, we have updated our estimate of both its useful life and residual value based on the new weighted average useful life of its current components. The impact of the change in estimate is accounted for on a prospective basis and is not material. Fully depreciated assets on the vessel were also removed from the ship and ship improvement’s cost and accumulated depreciation. Depreciation expense for the years ended December 31, 2020, 2019 and 2018 was $707.9 million, $627.7 million and $534.9 million, respectively. Repairs and maintenance expenses including Dry-dock expenses were $129.9 million, $199.7 million and $199.5 million for the years ended December 31, 2020, 2019 and 2018, respectively, and were recorded within other cruise operating expense. Ships under construction include progress payments to the shipyard, planning and design fees and other associated costs. Capitalized interest costs which were primarily associated with the construction or revitalization of ships amounted to $25.2 million, $32.9 million and $30.4 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2020
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	8. Long-Term Debt Long-term debt consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest Rate ​ ​ ​ Balance ​ ​ December 31, ​ Maturities ​ December 31, ​ 2020 2019 Through 2020 2019 ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) $875.0 million senior secured Revolving Loan Facility 1.90 % — ​ 2024 ​ $ 875,000 ​ $ — $75.0 million revolving credit line ​ — ​ 2.75 % 2020 ​ ​ — ​ ​ 75,000 Term Loan A Facility 1.93 % 3.06 % 2024 ​ 1,536,417 ​ 1,565,512 $400.0 million L. Catterton exchangeable notes (1) ​ 7.00 % — ​ 2026 ​ ​ 638,185 ​ ​ — $862.5 million 6.000% exchangeable notes (2) ​ 6.00 % — ​ 2024 ​ ​ 1,444,889 ​ ​ — $450.0 million 5.375% exchangeable notes (3) ​ 5.38 % — ​ 2025 ​ ​ 608,645 ​ ​ — $675.0 million 12.25% senior secured notes (4) ​ 12.25 % — ​ 2024 ​ ​ 650,178 ​ ​ — $750.0 million 10.25% senior secured notes ​ 10.25 % — ​ 2026 ​ ​ 739,295 ​ ​ — $850.0 million 5.875% senior unsecured notes ​ 5.88 % — ​ 2026 ​ ​ 837,659 ​ ​ — $565.0 million 3.625% senior unsecured notes ​ 3.63 % 3.63 % 2024 ​ ​ 560,019 ​ ​ 558,781 $260 million Norwegian Jewel term loan 1.52 % 2.54 % 2022 ​ 221,718 ​ 221,860 $230 million Pride of America term loan ​ 1.15 % 2.81 % 2022 ​ ​ 229,558 ​ ​ 229,621 €529.8 million Breakaway one loan (5) 1.15 % 2.84 % 2025 ​ 307,529 ​ 305,969 €529.8 million Breakaway two loan (5) 3.90 % 4.10 % 2026 ​ 343,214 ​ 370,531 €590.5 million Breakaway three loan (5) 2.83 % 2.98 % 2027 ​ 481,085 ​ 478,665 €729.9 million Breakaway four loan (5) 2.85 % 2.98 % 2029 ​ 633,699 ​ 630,088 €710.8 million Seahawk 1 term loan (5) 3.69 % 3.92 % 2030 ​ 695,843 ​ 692,150 €748.7 million Seahawk 2 term loan (5) 3.71 % 3.92 % 2031 ​ 860,212 ​ 856,188 Leonardo newbuild one loan 2.68 % 2.68 % 2034 ​ 95,563 ​ 48,009 Leonardo newbuild two loan 2.77 % 2.77 % 2035 ​ 48,009 ​ 48,009 Leonardo newbuild three loan 1.22 % 1.22 % 2036 ​ 46,519 ​ 42,700 Leonardo newbuild four loan 1.31 % 1.31 % 2037 ​ 46,519 ​ 42,700 Splendor newbuild loan 2.97 % — ​ 2032 ​ 402,177 ​ — Explorer newbuild loan 3.39 % 3.43 % 2028 ​ 251,634 ​ 242,449 Marina newbuild loan 1.03 % 2.75 % 2025 ​ 134,821 ​ 156,319 Riviera newbuild loan 0.96 % 2.48 % 2024 ​ 203,038 ​ 202,233 Term loan - newbuild related ​ 2.50 % — ​ 2021 ​ ​ 26,387 ​ ​ — Finance lease and license obligations Various ​ Various ​ 2028 ​ 27,547 ​ 34,909 Total debt ​ 12,945,359 ​ 6,801,693 Less: current portion of long-term debt ​ (124,885) ​ (746,358) Total long-term debt ​ $ 12,820,474 ​ $ 6,055,335 (1) Includes a conversion option of $623.2 million and related debt discount of $399.4 million as of December 31, 2020. (2) Includes a conversion option of $921.0 million and related debt discount of $309.8 million as of December 31, 2020. (3) Includes a conversion option of $311.9 million and related debt discount of $142.4 million as of December 31, 2020. (4) Includes original issue discount of $5.9 million as of December 31, 2020. (5) Currently U.S. dollar-denominated. ​ Credit Facilities In March 2020, NCLC had borrowed the full amount of $875 million under its existing Revolving Loan Facility maturing on January 2, 2024. In March 2020, NCLC entered into a $675 million revolving credit facility maturing on March 4, 2021, with JPMorgan Chase LIBOR plus a margin of 0.80% extended the maturity date of the revolving facility commitments under the Epic Credit Facility to March 3, 2022. The revolving facility loans accrued interest at a per annum rate based on LIBOR plus a margin of 1.75% in the case of Eurocurrency loans or at a per annum rate based on the base rate plus a margin of 0.75% in the case of base rate loans. The Epic Credit Facility was repaid in July 2020 and terminated as discussed below. In July 2020, NCLC entered into a EUR 31.2 million loan facility for newbuild related payments. The facility bears interest at a rate of 2.5% per annum. As of December 31, 2020, EUR 21.6 million was drawn under this facility and now matures on April 15, 2022. ​ Modifications ​ In April 2020, NCLC amended an aggregate amount of $386 million of export credit backed facilities that finance Norwegian Breakaway, Norwegian Getaway, Norwegian Escape, Norwegian Joy, Norwegian Bliss and Norwegian Encore to incorporate the terms of a 12-month debt holiday initiative offered to the cruise industry by Euler Hermes Aktiengesellschaft (“Hermes”), the official export credit agency of Germany. The debt holiday was initiated to provide interim debt service and financial covenant relief for borrowers during the current global COVID-19 pandemic with respect to their Hermes guaranteed financings. The amended agreements provide that, among other things, (a) amortization payments due from April 1, 2020 to March 31, 2021 (the “Deferral Period”) on the loans will be deferred and (b) the principal amounts so deferred will constitute separate tranches of loans under the facilities. The separate tranches of loans will accrue interest at a floating rate per annum based on six-month LIBOR plus a margin as follows: ​ ​ ​ ​ ​ ​ ​ Margin ​ €529.8 million Breakaway one loan (Norwegian Breakaway) ​ 0.90 % €529.8 million Breakaway two loan (Norwegian Getaway) ​ 1.20 % €590.5 million Breakaway three loan (Norwegian Escape) ​ 1.50 % €729.9 million Breakaway four loan (Norwegian Joy) ​ 1.50 % €710.8 million Seahawk 1 term loan (Norwegian Bliss) ​ 1.00 % €748.7 million Seahawk 2 term loan (Norwegian Encore) ​ 1.00 % ​ After the end of the Deferral Period, the deferred amounts will amortize in eight equal semiannual installments. See “—2021 Debt Modifications” below for amendments to these facilities subsequent to December 31, 2020. ​ Also, in April 2020, NCLC amended its $230 million credit agreement, dated as of January 10, 2019, with Nordea Bank ABP, New York Branch, as administrative agent, and certain other lenders. The amendment extends the maturity date of the term loan to January 10, 2022. From January 10, 2021 to January 10, 2022, the loan shall accrue interest at a per annum rate based on LIBOR plus a margin of 1.75% in the case of Eurocurrency loans or at a per annum rate based on the base rate plus a margin of 0.75% in the case of base rate loans. ​ In May 2020, NCLC amended its $260 million credit agreement, dated as of May 15, 2019, with Bank of America, N.A., as administrative agent and collateral agent, and certain other lenders. The amendment provides that (a) amortization payments due through May 1, 2021 will be deferred following the consummation of certain debt and equity financings, which resulted in aggregate gross proceeds greater than the amount required for the extension and (b) the principal amount so deferred will constitute a separate tranche of loans under the facility (the “Deferred Jewel Loans”). The Deferred Jewel Loans will accrue interest at a per annum rate based on LIBOR plus a margin of 2.50% in the case of Eurocurrency loans or at a per annum rate based on the base rate plus a margin of 1.50% in the case of base rate loans. After the end of the deferral period, the deferred loan payments will amortize in an aggregate principal amount equal to 25% per annum in semiannual installments, and in the case of such payment due on the maturity date, an amount equal to the then unpaid principal amount of the Deferred Jewel Loans outstanding. NCLC entered into a Fifth Amended and Restated Credit Agreement, dated as of May 8, 2020 (the “Fifth ARCA”), with a subsidiary of NCLC, as co-borrower and JPMorgan Chase Bank, N.A., as administrative agent, and lenders holding 87.57% of the term loans outstanding (the “Fifth ARCA Deferring Lenders”). This revised facility provides that, among other things, (a) amortization payments due within the first year after effectiveness on the loans under the Term Loan A Facility held by the Fifth ARCA Deferring Lenders will be deferred and (b) the principal amount so deferred will constitute a separate tranche of loans (the “Deferred Term Loan A”). The Deferred Term Loan A will accrue interest (x) in the case of Eurocurrency loans, at a per annum rate based on LIBOR plus a margin of 2.50% or (y) in the case of base rate loans, at a per annum rate based on the base rate plus a margin of 1.50%. After the end of the deferral period, the Deferred Term Loan A will amortize in an aggregate principal amount equal to 25% per annum of the Deferred Term Loan A, in quarterly installments, and in the case of such payment due on the maturity date, an amount equal to the then unpaid principal amount of the Deferred Term Loan A outstanding . The Term Loan A Facility (other than the Deferred Term Loan A) that is held by the Fifth ARCA Deferring Lenders shall constitute a separate class of loans (the “Term Loan A-1”), with the same terms as the Term Loan A Facility under the Fourth Amended and Restated Credit Agreement, except that the amortization payments on the Term Loan A-1 shall be deferred during the deferral period. The portion of the Term Loan A Facility that is held by lenders other than the Fifth ARCA Deferring Lenders shall constitute a separate class of loans (the “Legacy Term Loan A”) with the same terms as the Term Loan A Facility under the Fourth Amended and Restated Credit Agreement. See “—2021 Debt Modifications” below for amendments to this facility subsequent to December 31, 2020. In June 2020, NCLC amended the credit facilities secured by Seven Seas Explorer, Seven Seas Splendor, Riviera, Marina, Leonardo One and Leonardo Two to defer amortization with respect to certain of the debt outstanding under the agreements (the “Supplemental Agreements”). The amendments for the Seven Seas Explorer, Seven Seas Splendor, Riviera, Marina, Leonardo One and Leonardo Two facilities summarized below provide $156 million of incremental liquidity to the Company through March 2021 and are subject to certain customary conditions. The Supplemental Agreements of Seven Seas Explorer, Seven Seas Splendor, Riviera, and Marina provide that, among other things, (a) amortization payments due during the Deferral Period on the loans will be deferred and (b) the principal amount so deferred will constitute a separate tranche of loans (the “Deferred Loans”). The Deferred Loans will accrue interest at a floating rate per annum based on six-month LIBOR plus a margin as follows: ​ ​ ​ ​ ​ ​ ​ Margin ​ Explorer newbuild loan ​ 2.80 % Splendor newbuild loan ​ 1.75 % Marina newbuild loan ​ 0.55 % Riviera newbuild loan ​ 0.55 % ​ ​ After the end of the Deferral Period, the Deferred Loans will amortize in an aggregate principal amount equal to 25% per annum of the Deferred Loans, in semiannual installments. Consistent with our amendments to our Hermes-backed credit facilities described above, the Supplemental Agreements provide financial covenant relief and additional restrictions on restricted payments and certain other covenants were added. See “—2021 Debt Modifications” below for amendments to these facilities subsequent to December 31, 2020. The above modifications resulted in aggregate modification costs of $17.3 million and a loss on extinguishment of debt of $5.0 million, which are recognized in interest expense, net for the year ended December 31, 2020. Secured Notes In May 2020, NCLC conducted a private offering of $675.0 million aggregate principal amount of 12.25% senior secured notes due May 15, 2024 (the “2024 Senior Secured Notes”) at 99% original issue discount. The 2024 Senior Secured Notes pay interest at 12.25% per annum, semiannually on May 15 and November 15 of each year, to holders of record at the close of business on the immediately preceding May 1 and November 1, respectively. NCLC may redeem the 2024 Senior Secured Notes, in whole or part, at any time prior to February 15, 2024, at a price equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date and a “make-whole premium.” NCLC may redeem the 2024 Senior Secured Notes, in whole or in part, on or after February 15, 2024, at a price equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date. At any time and from time to time prior to February 15, 2022, NCLC may choose to redeem up to 35% of the aggregate principal amount of the 2024 Senior Secured Notes with the net proceeds of certain equity offerings, subject to certain restrictions, at a redemption price equal to 112.25% of the principal amount of the 2024 Senior Secured Notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date, so long as at least 65% of the aggregate principal amount of the 2024 Senior Secured Notes issued remains outstanding following such redemption. The 2024 Senior Secured Notes are secured by first-priority interests in, among other things and subject to certain agreed security principles, shares of capital stock in certain subsidiary guarantors, two of our vessels, our material intellectual property and two islands that we use in the operations of our cruise business. The 2024 Senior Secured Notes are also guaranteed by our subsidiaries that own the property that secures the 2024 Senior Secured Notes as well as certain additional subsidiaries whose assets do not secure the 2024 Senior Secured Notes. In July 2020, NCLC conducted a private offering of $750.0 million aggregate principal amount of 10.25% senior secured notes due February 1, 2026 (the “2026 Senior Secured Notes”). The 2026 Senior Secured Notes pay interest at 10.25% per annum, semiannually on February 1 and August 1 of each year, to holders of record at the close of business on the immediately preceding January 15 and July 15, respectively. NCLC may redeem the 2026 Senior Secured Notes, in whole or part, at any time prior to August 1, 2023, at a price equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date and a “make-whole premium.” NCLC may redeem the 2026 Senior Secured Notes, in whole or in part, on or after August 1, 2023, at the redemption prices set forth in the indenture for the 2026 Senior Secures Notes plus accrued and unpaid interest to, but excluding, the redemption date. At any time and from time to time prior to August 1, 2023, NCLC may choose to redeem up to 35% of the aggregate principal amount of the 2026 Senior Secured Notes with the net proceeds of certain equity offerings, subject to certain restrictions, at a redemption price equal to 110.25% of the principal amount of the 2026 Senior Secured Notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date, so long as at least 65% of the aggregate principal amount of the 2026 Senior Secured Notes issued remains outstanding following such redemption. NCLC used a portion of the proceeds from the offering of the 2026 Senior Secured Notes to repay the $675 million principal amount plus accrued and unpaid interest outstanding under the Epic Credit Facility, which was secured by the Norwegian Epic. Following the termination of the Epic Credit Facility, the vessel owned and operated by Norwegian Epic, Ltd. was released as collateral, thereby enabling the 2026 Senior Secured Notes and certain of the related guarantees to be secured by a first-priority security interest in, among other things and subject to certain agreed security principles, the Norwegian Epic. The repayment and termination of the Epic Credit Facility resulted in a loss on extinguishment of $5.5 million, which was recognized in interest expense, net for the year ended December 31, 2020. The indentures governing the 2024 Senior Secured Notes and 2026 Senior Secured Notes include requirements that, among other things and subject to a number of qualifications and exceptions, restrict the ability of NCLC and its restricted subsidiaries, as applicable, to (i) incur or guarantee additional indebtedness; (ii) pay dividends or distributions on, or redeem or repurchase, equity interests and make other restricted payments; (iii) make investments; (iv) consummate certain asset sales; (v) engage in certain transactions with affiliates; (vi) grant or assume certain liens; and (vii) consolidate, merge or transfer all or substantially all of their assets. Exchangeable Notes In May 2020, NCLC conducted a private offering of $862.5 million aggregate principal amount of 6.00% exchangeable senior notes due May 15, 2024 (the “2024 Exchangeable Notes”). The 2024 Exchangeable Notes are guaranteed by NCLH on a senior basis. Holders may exchange their 2024 Exchangeable Notes at their option into redeemable preference shares of NCLC. Upon exchange, the preference shares will be immediately and automatically exchanged, for each $1,000 principal amount of exchanged 2024 Exchangeable Notes, into a number of NCLH’s ordinary shares based on the exchange rate. The exchange rate will initially be 72.7273 ordinary shares per $1,000 principal amount of 2024 Exchangeable Notes (equivalent to an initial exchange price of approximately $13.75 per ordinary share). The maximum exchange rate is 89.4454 and reflects potential adjustments to the initial exchange rate, which would only be made in the event of certain make-whole fundamental changes or tax redemption events. The exchange rate referred to above is also subject to adjustment for any stock split, stock dividend or similar transaction. The 2024 Exchangeable Notes pay interest at Also in May 2020, NCLH and NCLC entered into an investment agreement with an affiliate of L Catterton (the “Private Investor”), pursuant to which NCLC agreed to sell and issue to the Private Investor (the “Private Exchangeable Notes Transaction”) up to $400 million in aggregate principal amount of exchangeable senior notes due June 1, 2026 (the “Private Exchangeable Notes”). The Private Exchangeable Notes Transaction closed on May 28, 2020. The Private Exchangeable Notes accrue interest at a rate of 7.0% per annum for the first year post-issuance (which will accrete to the principal amount), 4.5% per annum interest (which will accrete to the principal amount) plus 3.0% per annum cash interest for the following four years and 7.5% per annum in cash interest for the final year prior to maturity. The Private Investor has certain registration rights in respect of NCLH’s ordinary shares underlying the Private Exchangeable Notes and is subject to certain customary transfer, voting and standstill restrictions. The Private Exchangeable Notes are guaranteed by NCLH on a senior basis. Holders may exchange their Private Exchangeable Notes at their option into redeemable preference shares of NCLC. Upon exchange, the preference shares will be immediately and automatically exchanged, for each $1,000 principal amount of exchanged Private Exchangeable Notes, into a number of NCLH’s ordinary shares based on the exchange rate. The exchange rate will initially be approximately 82.6446 ordinary shares per $1,000 principal amount of Private Exchangeable Notes (equivalent to an initial exchange price of $12.10 per ordinary share). The maximum exchange rate is 90.9090 and reflects potential adjustments to the initial exchange rate, which would only be made in the event of certain make-whole fundamental changes or tax redemption events. The exchange rate referred to above is also subject to adjustment for any stock split, stock dividend or similar transaction. NCLC has the right to redeem all or a portion of the Private Exchange Notes at any time after the third anniversary of the issuance date at a price equal to 100% of the accreted principal amount thereof if the market closing price of NCLH’s ordinary shares has been at least 250% of the per share price implied by the exchange rate then in effect for at least 20 trading days during any 30 consecutive trading day period. In July 2020, NCLC conducted a private offering of $450.0 million aggregate principal amount of 5.375% exchangeable senior notes due August 1, 2025 (the “2025 Exchangeable Notes”). The 2025 Exchangeable Notes are guaranteed by NCLH on a senior basis. Holders may exchange their 2025 Exchangeable Notes at their option into redeemable preference shares of NCLC. Upon exchange, the preference shares will be immediately and automatically exchanged, for each $1,000 principal amount of exchanged 2025 Exchangeable Notes, into a number of NCLH’s ordinary shares based on the exchange rate. The exchange rate will initially be 53.3333 ordinary shares per $1,000 principal amount of 2025 Exchangeable Notes (equivalent to an initial exchange price of approximately $18.75 per ordinary share). The maximum exchange rate is 66.6666 and reflects potential adjustments to the initial exchange rate, which would only be made in the event of certain make-whole fundamental changes or tax redemption events. The exchange rate referred to above is also subject to adjustment for any stock split, stock dividend or similar transaction. The 2025 Exchangeable Notes pay interest at The 2024 Exchangeable Notes, 2025 Exchangeable Notes and Private Exchangeable Notes contain equity conversion options with a value of $1.9 billion as of December 31, 2020, which have been bifurcated from the debt host contracts. We refer you to Note 10 – “Fair Value Measurements and Derivatives” for further information. The net carrying amounts of the liability components of our exchangeable notes consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 Principal amount ​ $ 1,726,811 Less: Unamortized debt discount, including deferred financing fees ​ ​ (891,236) Net carrying value ​ $ 835,575 ​ The remaining period over which the unamortized debt discount will be recognized as non-cash interest expense is 3.4 years, 4.6 years and 5.4 years for the 2024 Exchangeable Notes, 2025 Exchangeable Notes and Private Exchangeable Notes, respectively. The following table presents the interest expense recognized related to the exchangeable notes (in thousands): ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2020 Interest expense, including amortization of debt discounts and coupon interest ​ $ 130,949 ​ The effective interest rate is 22.78% and 15.89% for the 2024 Exchangeable Notes and 2025 Exchangeable Notes, respectively. The share price of NCLH, to which the value of the conversion option is indexed, had increased significantly between the execution of the agreement for the Private Exchangeable Notes and the date of issuance. As a result, the fair value of the conversion option at issuance exceeded the net proceeds received, and the carrying value of the note recognized was zero, which created an effective interest rate that was not measurable. The excess of the fair value over the net proceeds received was recognized as a loss within other income (expense), net. As the associated financing costs would create a negative carrying value for the note, they were charged to expense in other income (expense), net. Unsecured Notes In December 2020, NCLC conducted a private offering of $850.0 million aggregate principal amount of 5.875% senior secured notes due March 15, 2026 (the “2026 Senior Unsecured Notes”). The 2026 Senior Unsecured Notes pay interest at 5.875% per annum, semiannually on March 15 and September 15 of each year, commencing on March 15, 2021, to holders of record at the close of business on the immediately preceding March 1 and September 1, respectively. NCLC may redeem the 2026 Senior Unsecured Notes, in whole or part, at any time prior to December 15, 2025, at a price equal to 100% of the principal amount of the notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date and a “make-whole premium.” NCLC may redeem the 2026 Senior Unsecured Notes, in whole or in part, on or after December 15, 2025, at a price equal to 100% of the principal amount of the notes plus accrued and unpaid interest to, but excluding, the redemption date. At any time and from time to time prior to December 15, 2022, NCLC may choose to redeem up to 40% of the aggregate principal amount of the 2026 Senior Unsecured Notes with the net proceeds of certain equity offerings, subject to certain restrictions, at a redemption price equal to 105.875% of the principal amount of the 2026 Senior Unsecured Notes redeemed plus accrued and unpaid interest to, but excluding, the redemption date, so long as at least 60% of the aggregate principal amount of the 2026 Senior Unsecured Notes issued remains outstanding following such redemption. The indenture governing the 2026 Senior Unsecured Notes includes requirements that, among other things and subject to a number of qualifications and exceptions, restrict the ability of NCLC and its restricted subsidiaries, as applicable, to (i) incur or guarantee additional indebtedness; (ii) pay dividends or distributions on, or redeem or repurchase, equity interests and make other restricted payments; (iii) make investments; (iv) consummate certain asset sales; (v) engage in certain transactions with affiliates; (vi) grant or assume certain liens; and (vii) consolidate, merge or transfer all or substantially all of their assets. 2021 Modifications On January 29, 2021, NCLC entered into an amendment agreement (the “First Amendment”), which amends the Fifth ARCA (as amended by the First Amendment, the “Senior Secured Credit Facility”). The First Amendment provides that, among other things, (a) amortization payments due between the First Amendment effective date and prior to June 30, 2022 (the “First Amendment Deferral Period”) on the Legacy Term Loan A and Term Loan A-1 held by lenders that have consented to such deferral (the “First Amendment Deferring Lenders”) are deferred and such deferred principal amount constitutes a separate tranche of loans (the “Deferred Term Loan A-1”) and (b) the Deferred Term Loan A loans of First Amendment Deferring Lenders were converted into Deferred Term Loan A-1 loans. The Legacy Term Loan A and Term Loan A-1 that were held by the First Amendment Deferring Lenders (other than amounts converted into the Deferred Term Loan A-1) constitute a separate tranche of loans (the “Term Loan A-2”), with the same terms as the Legacy Term Loan A and Term Loan A-1 under the Fifth ARCA, except that amortization payments on the Term Loan A-2 shall be deferred during the First Amendment Deferral Period and thereafter such Term Loan A-2 will amortize in an aggregate principal amount equal to approximately 5.88% per annum and the interest rate for Term Loan A-2 shall be modified as described below. The Deferred Term Loan A-1 will accrue interest (x) in the case of Eurocurrency loans, at a per annum rate based on LIBOR plus a margin of 2.50% or (y) in the case of base rate loans, at a per annum rate based on the base rate plus a margin of 1.50%. After the end of the First Amendment Deferral Period, the Deferred Term Loan A-1 will amortize in an aggregate principal amount equal to 25% per annum of the Deferred Term Loan A-1 outstanding immediately after the consummation of the First Amendment, in quarterly installments, and in the case of such payment due on the maturity date, an amount equal to the then unpaid principal amount of the Deferred Term Loan A-1 outstanding. The Legacy Term Loan A, Term Loan A-1 and Deferred Term Loan A that were held by lenders other than the First Amendment Deferring Lenders constitute separate classes of loans and were unchanged. The First Amendment resulted in deferred amortization payments aggregating approximately $70 million prior to June 30, 2022. The First Amendment provides that, (a) from the First Amendment effective date to and including December 31, 2022 (the “Covenant Relief Period”) the testing of the loan to value, debt to capitalization and EBITDA to debt service covenants under the Senior Secured Credit Facility will be suspended and the free liquidity test will be replaced by a covenant to maintain at least $200 million in free liquidity, certified on a monthly basis. During the Covenant Relief Period the interest rate for Term Loan A-2 and revolving loans held by Lenders that consented to the First Amendment will be LIBOR plus 2.00% (or base rate plus 1.00%) with decreases subject to a leverage-based pricing grid. The First Amendment also makes certain other changes to the Senior Secured Credit Facility, including tightening certain of the baskets applicable to our ability make certain asset dispositions, investments and restricted payments. In addition, in February 2021, NCLC amended all of its export-credit backed facilities to defer amortization payments aggregating approximately $680 million through March 31, 2022 and/or make certain changes in respect of covenants and undertakings contained therein. The facilities that finance Norwegian Breakaway, Norwegian Getaway, Norwegian Escape, Norwegian Joy, Norwegian Bliss, Norwegian Encore, Seven Seas Explorer, Seven Seas Splendor, Riviera and Marina were amended to provide that, among other things, (a) amortization payments due from April 1, 2021 to March 31, 2022 (the “Second Deferral Period”) on the loans will be deferred and (b) the principal amounts so deferred will constitute separate tranches of loans under the facilities. The separate tranches of loans will accrue interest at a floating rate per annum based on six-month LIBOR plus a margin as follows: ​ ​ ​ ​ ​ ​ ​ Margin ​ €529.8 million Breakaway one loan (Norwegian Breakaway) ​ 1.10 % €529.8 million Breakaway two loan (Norwegian Getaway) ​ 1.40 % €590.5 million Breakaway three loan (Norwegian Escape) ​ 1.50 % €729.9 million Breakaway four loan (Norwegian Joy) ​ 1.50 % €710.8 million Seahawk 1 term loan (Norwegian Bliss) ​ 1.20 % €748.7 million Seahawk 2 term loan (Norwegian Encore) ​ 1.20 % Explorer newbuild loan ​ 3.00 % Splendor newbuild loan ​ 1.95 % Marina newbuild loan ​ 0.75 % Riviera newbuild loan ​ 0.75 % ​ After the end of the Second Deferral Period, the deferred loans will amortize in an aggregate principal amount equal to 20% per annum of the deferred loans, in semiannual installments. In addition, all of NCLC’s export-credit backed facilities were amended to provide that, from the effective date of the amendments to and including December 31, 2022, certain of the financial covenants under such facilities will be suspended and the free liquidity test will be replaced by a covenant to maintain at least $200 million in free liquidity. The amendments also made certain other changes to the facilities, including imposing further restrictions on NCLC’s ability to incur debt, create security, issue equity and make dividends and other distributions. Interest Expense Interest expense, net for the year ended December 31, 2020 was $520.1 million which included $42.2 million of amortization of deferred financing fees and a $27.8 million loss on extinguishment and modification of debt. Interest expense, net for the year ended December 31, 2019 was $272.9 million which included $27.5 million of amortization of deferred financing fees and a $16.7 million loss on extinguishment of debt. Interest expense, net for the year ended December 31, 2018 was $270.4 million which included $31.4 million of amortization of deferred financing fees and a $6.3 million loss on extinguishment and modification of debt. Debt Repayments As a result of the aforementioned executed amendments, we have reclassified $671.1 million of debt which was originally classified as a current liability based on the contractual maturities outstanding at December 31, 2020 to long-term debt. The following are scheduled principal repayments on long-term debt, including finance lease obligations, as of December 31, 2020 for each of the next five years (in thousands): ​ ​ ​ ​ ​ Year Amount 2021 ​ $ 124,829 2022 ​ 1,192,923 2023 ​ 917,893 2024 ​ 5,051,867 2025 ​ 1,045,773 Thereafter ​ 3,818,798 Total ​ $ 12,152,083 ​ We had an accrued interest liability of $101.9 million and $33.3 million as of December 31, 2020 and 2019, respectively. ​ Debt Covenants At December 31, 2020, we were in compliance with all of our debt covenants. Subsequent to December 31, 2020, we have received certain financial and other debt covenant waivers through December 31, 2022 and added new free liquidity requirements. If we do not continue to remain in compliance with our covenants, including following the expiration of any current waivers, we would have to seek additional amendments to our covenants. However, no assurances can be made that such amendments would be approved by our lenders. Generally, if an event of default under any debt agreement occurs, then pursuant to cross default and/or cross acceleration clauses, substantially all of our outstanding debt and derivative contract payables could become due, and all

Related Party Disclosures

Related Party Disclosures	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Disclosures	9. Related Party Disclosures NCLC, as issuer, NCLH, as guarantor, and U.S. Bank National Association, as trustee are all parties to an indenture, dated May 28, 2020 (the “Indenture”) related to the Private Exchangeable Notes, which are currently held by the Private Investor. The terms of the Indenture are more fully described under Note 8 — “Long-Term Debt”. Based on the initial exchange rate, the Private Investor beneficially owned over 10% of NCLH’s outstanding ordinary shares as of December 31, 2020. The initial exchange rate in the Private Exchangeable Notes may be adjusted in the event of certain make-whole fundamental changes or tax redemption events (each, as described in the Indenture), but the maximum number of NCLH ordinary shares issuable upon an exchange in the event of such an adjustment would not exceed 46,577,947 . The Private Exchangeable Notes also contain certain anti-dilution provisions that could subject the exchange rate to additional adjustment if certain events occur. NCLH, NCLC and the Private Investor also entered into an investor rights agreement dated May 28, 2020 (the “Investor Rights Agreement”) which provides that, among other things, the Private Investor is entitled to nominate one person who will be appointed to the board of directors of NCLH until the first date on which the Private Investor no longer beneficially owns in the aggregate at least 50% of the number of NCLH’s ordinary shares issuable upon exchange of the Private Exchangeable Notes beneficially owned by the Private Investor in the aggregate as of May 28, 2020 (subject to certain adjustments). The Investor Rights Agreement also provides for customary registration rights for the Private Investor and its affiliates, including demand and piggyback registration rights, contains customary transfer restrictions and provides that the Private Investor and its affiliates are subject to a voting agreement with respect to certain matters during a specified period of time.

Fair Value Measurements and Der

Fair Value Measurements and Derivatives	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements and Derivatives	10. Fair Value Measurements and Derivatives Fair value is defined as the price at which an orderly transaction to sell an asset or to transfer a liability would take place between market participants at the measurement date under current market conditions (that is, an exit price at the measurement date from the perspective of a market participant that holds the asset or owes the liability). Fair Value Hierarchy The following hierarchy for inputs used in measuring fair value should maximize the use of observable inputs and minimize the use of unobservable inputs by requiring that the most observable inputs be used when available: Level 1 — Quoted prices in active markets for identical assets or liabilities that are accessible at the measurement dates. Level 2 — Significant other observable inputs that are used by market participants in pricing the asset or liability based on market data obtained from independent sources. Level 3 — Significant unobservable inputs we believe market participants would use in pricing the asset or liability based on the best information available. Derivatives We are exposed to market risk attributable to changes in interest rates, foreign currency exchange rates and fuel prices. We attempt to minimize these risks through a combination of our normal operating and financing activities and through the use of derivatives. We assess whether derivatives used in hedging transactions are “highly effective” in offsetting changes in the cash flow of our hedged forecasted transactions. We use regression analysis for this hedge relationship and high effectiveness is achieved when a statistically valid relationship reflects a high degree of offset and correlation between the fair values of the derivative and the hedged forecasted transaction. Cash flows from the derivatives are classified in the same category as the cash flows from the underlying hedged transaction. If it is determined that the hedged forecasted transaction is no longer probable of occurring, then the amount recognized in accumulated other comprehensive income (loss) is released to earnings. There are no amounts excluded from the assessment of hedge effectiveness and there are no credit-risk-related contingent features in our derivative agreements. We monitor concentrations of credit risk associated with financial and other institutions with which we conduct significant business. Credit risk, including but not limited to counterparty non-performance under derivatives, is not considered significant, as we primarily conduct business with large, well-established financial institutions with which we have established relationships, and which have credit risks acceptable to us, or the credit risk is spread out among many creditors. We do not anticipate non-performance by any of our significant counterparties. As of December 31, 2020, we had fuel swaps, which are used to mitigate the financial impact of volatility of fuel prices pertaining to approximately 596 thousand metric tons of our projected fuel purchases, maturing through December 31, 2023 . Beginning in July 2020, our fuel swaps designated as hedges for heavy fuel oil failed the effectiveness tests required for recognition within accumulated other comprehensive income (loss). As a result, the change in fair value related to these fuel swaps have been recognized in other income (expense), net for July through September of 2020. On November 1, 2020, the approximately 197 thousand metric tons of fuel hedges for heavy fuel oil maturing through December 31, 2022 were dedesignated as cash flow hedges. As of December 31, 2020, we had fuel swaps which were not designated as cash flow hedges. Due to a decrease in forecasted fuel consumption resulting from voyage cancellations due to COVID-19, we released into earnings fuel hedges of approximately 89 thousand metric tons of fuel as these forecasted transactions were no longer probable of occurring. The agreements mature through September 30, 2021 . As of December 31, 2020, we had foreign currency forward contracts, matured foreign currency options and matured foreign currency collars which are used to mitigate the financial impact of volatility in foreign currency exchange rates related to our ship construction contracts denominated in euros. The notional amount of our foreign currency forward contracts was €1.9 billion, or $2.3 billion based on the euro/U.S. dollar exchange rate as of December 31, 2020. As of December 31, 2020, we had interest rate swaps and collars which are used to hedge our exposure to interest rate movements and manage our interest expense. The notional amount of our outstanding debt associated with the interest rate swaps and collars was $0.7 billion as of December 31, 2020. As of December 31, 2020, we had conversion options embedded in our exchangeable notes. The notional amounts of our outstanding options as of December 31, 2020 were 62.7 million, 24.0 million and 34.2 million NCLH shares for the 2024 Exchangeable Notes, 2025 Exchangeable Notes and Private Exchangeable Notes, respectively. The derivatives measured at fair value and the respective location in the consolidated balance sheets includes the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets ​ Liabilities ​ ​ ​ ​ ​ December 31, ​ December 31, ​ December 31, ​ December 31, ​ ​ Balance Sheet Location 2020 2019 2020 2019 ​ Derivative Contracts Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ ​ ​ ​ Other long-term assets ​ $ — ​ $ 277 ​ $ — ​ $ — ​ ​ Accrued expenses and other liabilities ​ — ​ 2,300 ​ 35,973 ​ 18,257 ​ ​ Other long-term liabilities ​ — ​ 683 ​ 28,947 ​ 17,763 ​ Foreign currency contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prepaid expenses and other assets ​ 5,779 ​ — ​ — ​ — ​ ​ Other long-term assets ​ 43,250 ​ — ​ — ​ — ​ ​ Accrued expenses and other liabilities ​ — ​ — ​ 14,778 ​ 33,475 ​ ​ Other long-term liabilities ​ 6,821 ​ 169 ​ 44,938 ​ 118,500 ​ Interest rate contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accrued expenses and other liabilities ​ — ​ — ​ 6,776 ​ 2,178 ​ ​ ​ Other long-term liabilities ​ ​ — ​ ​ — ​ ​ 452 ​ ​ 1,861 ​ Total derivatives designated as hedging instruments ​ ​ ​ $ 55,850 ​ $ 3,429 ​ $ 131,864 ​ $ 192,034 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivative Contracts Not Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ Accrued expenses and other liabilities ​ $ 546 ​ $ — ​ $ 6,732 ​ $ — ​ ​ ​ Other long-term liabilities ​ ​ — ​ ​ — ​ ​ 3,534 ​ ​ — ​ Debt conversion options Exchangeable notes ​ ​ — ​ ​ — ​ ​ 1,856,145 ​ ​ — ​ Total derivatives not designated as hedging instruments ​ ​ ​ $ 546 ​ $ — ​ $ 1,866,411 ​ $ — ​ Total derivatives ​ ​ ​ $ 56,396 ​ $ 3,429 ​ $ 1,998,275 ​ $ 192,034 ​ ​ The fair values of swap and forward contracts are determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets. The Company determines the value of options and collars utilizing option pricing models based on inputs that are either readily available in public markets or can be derived from information available in publicly quoted markets. The option pricing models used by the Company are industry standard models for valuing options and are used by the broker/dealer community. The inputs to the option pricing models are the option strike prices, underlying prices, risk-free rates of interest, time to expiration, and both historical and implied volatilities. The fair values of option contracts consider both the intrinsic value and any remaining time value associated with those derivatives that have not yet settled. The Company also considers counterparty credit risk and its own credit risk in its determination of all estimated fair values. Our derivatives and financial instruments were categorized as Level 2 in the fair value hierarchy, and we had no derivatives or financial instruments categorized as Level 1 or Level 3. Our derivative contracts include rights of offset with our counterparties. We have elected to net certain assets and liabilities within counterparties when the rights of offset exist. We are not required to post cash collateral related to our derivative instruments. The gross and net amounts recognized within assets and liabilities include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Gross ​ ​ ​ ​ Gross ​ Amounts ​ Total Net ​ Amounts ​ ​ ​ December 31, 2020 ​ Amounts ​ Offset ​ Amounts ​ Not Offset ​ Net Amounts Assets ​ $ 49,029 ​ $ — ​ $ 49,029 ​ $ (49,029) ​ $ — Liabilities ​ ​ 1,998,275 ​ ​ (7,367) ​ ​ 1,990,908 ​ ​ (1,913,496) ​ ​ 77,412 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Gross ​ ​ ​ ​ Gross ​ Amounts ​ Total Net ​ Amounts ​ ​ ​ December 31, 2019 ​ Amounts ​ Offset ​ Amounts ​ Not Offset ​ Net Amounts Assets ​ $ 277 ​ $ — ​ $ 277 ​ $ — ​ $ 277 Liabilities ​ ​ 192,034 ​ ​ (3,152) ​ ​ 188,882 ​ ​ (149,863) ​ ​ 39,019 ​ The effects of cash flow hedge accounting on accumulated other comprehensive income (loss) include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Location of Gain ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Loss) Reclassified ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ from Accumulated ​ Amount of Gain (Loss) Reclassified ​ Amount of Gain (Loss) ​ Other Comprehensive ​ from Accumulated Other ​ Recognized in Other ​ Income (Loss) into ​ Comprehensive Derivatives Comprehensive Income ​ Income ​ Income (Loss) into Income ​ Year Ended December 31, ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 ​ 2020 2019 2018 Fuel contracts $ (157,669) ​ $ 46,154 ​ $ (52,949) ​ Fuel ​ $ (45,488) ​ $ 14,093 ​ $ 34,410 Fuel contracts ​ — ​ ​ — ​ ​ — ​ Other income (expense), net ​ ​ (49,653) ​ — ​ — Foreign currency contracts 116,496 ​ (163,197) ​ (108,911) ​ Depreciation and amortization ​ (4,929) ​ (3,062) ​ (3,463) Interest rate contracts (10,469) ​ (5,972) ​ 646 ​ Interest expense, net ​ (6,600) ​ (2,133) ​ (851) Total gain (loss) recognized in other comprehensive income $ (51,642) ​ $ (123,015) ​ $ (161,214) ​ ​ $ (106,670) ​ $ 8,898 ​ $ 30,096 ​ The effects of cash flow hedge accounting on the consolidated statements of operations include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ ​ ​ Depreciation ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and ​ Interest ​ Other Income ​ ​ Fuel Amortization Expense, net (Expense), net Total amounts of income and expense line items presented in the consolidated statements of operations in which the effects of cash flow hedges are recorded ​ $ 264,712 ​ $ 717,840 ​ $ 520,063 ​ ​ (984,501) ​ ​ ​ ​ ​ ​ ​ Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into income ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ (45,488) ​ ​ — ​ ​ — ​ ​ — Foreign currency contracts ​ ​ — ​ ​ (4,929) ​ ​ — ​ ​ — Interest rate contracts ​ ​ — ​ ​ — ​ ​ (6,600) ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss reclassified from accumulated other comprehensive income (loss) into income as a result that a forecasted transaction is no longer probable of occurring ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ — ​ ​ — ​ ​ — ​ ​ (49,653) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of gain recognized in income as a result of failing effectiveness tests ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,507 ​ ​ The effects of cash flow hedge accounting on the consolidated statements of operations include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ Year Ended December 31, 2018 ​ ​ ​ ​ ​ Depreciation ​ ​ ​ ​ ​ ​ Depreciation ​ ​ ​ ​ ​ ​ ​ and ​ Interest ​ ​ ​ ​ and ​ Interest ​ Fuel Amortization Expense, net Fuel Amortization Expense, net Total amounts of income and expense line items presented in the consolidated statements of operations in which the effects of cash flow hedges are recorded ​ $ 409,602 ​ $ 646,188 ​ $ 272,867 ​ $ 392,685 ​ $ 561,060 ​ $ 270,404 ​ ​ ​ ​ ​ ​ ​ Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into income ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ 14,093 ​ ​ — ​ ​ — ​ ​ 34,410 ​ ​ — ​ ​ — Foreign currency contracts ​ ​ — ​ ​ (3,062) ​ ​ — ​ ​ — ​ ​ (3,463) ​ ​ — Interest rate contracts ​ ​ — ​ ​ — ​ ​ (2,133) ​ ​ — ​ ​ — ​ ​ (851) ​ The effects of derivatives not designated as hedging instruments on the consolidated statements of operations include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of Gain (Loss) Recognized in Income ​ ​ ​ Year Ended December 31, ​ Location of Gain (Loss) 2020 2019 2018 Derivatives not designated as hedging instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts Other income (expense), net ​ $ 20,932 ​ $ — ​ $ — Debt conversion options Other income (expense), net ​ ​ (938,614) ​ ​ — ​ ​ — ​ Long-Term Debt As of December 31, 2020 and 2019, the fair value of our long-term debt, including the current portion, was $14,197.8 million and $6,957.8 million, respectively, which was $1,047.0 million higher and $31.3 million higher, respectively, than the carrying values, excluding deferred financing costs. The difference between the fair value and carrying value of our long-term debt is due to our fixed and variable rate debt obligations carrying interest rates that are above or below market rates at the measurement dates. The fair value of our long-term revolving and term loan facilities was calculated based on estimated rates for the same or similar instruments with similar terms and remaining maturities. The fair value of our exchangeable notes considers observable risk-free rates; credit spreads of the same or similar instruments; and share prices, tenors, and historical and implied volatilities which are sourced from observable market data. The inputs are considered to be Level 2 in the fair value hierarchy. Market risk associated with our long-term variable rate debt is the potential increase in interest expense from an increase in interest rates or from an increase in share values. Non-Recurring Measurements of Non-Financial Assets Goodwill and trade names are nonfinancial instruments that are measured at fair value on a non-recurring basis. In January 2017, the FASB issued ASU No. 2017 04, Intangibles—Goodwill and Other (Topic 350) — Simplifying the Test for Goodwill Impairment, which simplifies the test for goodwill impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measured a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The guidance was adopted with an effective date of January 1, 2020, and therefore, our interim goodwill impairment tests as of March 31, 2020 were performed using only a Step 1 test. The Step 1 Test used discounted future cash flows and other market data to determine the estimated fair value of the reporting units at March 31, 2020, which are all considered Level 3 inputs. Our discounted cash flow valuation reflected our principal assumptions of 1) forecasted future operating results and growth rates, which have been prepared under multiple scenarios and are probability weighted, 2) forecasted capital expenditures for fleet growth and ship improvements and 3) a weighted average cost of capital of market participants. Historically, our Step 1 Test consisted of a combined approach using discounted future cash flows and market multiples to determine the estimated fair value of the reporting units. However, beginning with the Step 1 Test performed as of March 31, 2020 as a result of triggering events, the market multiples were used solely as a corroboratory approach given the impact of COVID-19 on the current year’s results, as of the valuation date, as well as prospective results including the lack of any guidance provided, which were not available for our peers. We concluded that this approach is the most representative method to estimate fair value as it utilizes expectations of long-term growth as well as current market conditions. For the trade names, we used the relief from royalty method, which uses the same forecasts and discount rates from the discounted cash flow valuation in the goodwill assessment along with a trade name royalty rate assumption. We believe that we made reasonable estimates and judgments. As of December 31, 2020, our annual review supports the carrying value of these assets; however, a change in our estimated future operating cash flows may result in a decline in estimated fair value in future periods, which may result in a need to recognize additional impairment charges. Other The carrying amounts reported in the consolidated balance sheets of all other financial assets and liabilities approximate fair value.

Employee Benefits and Share-Bas

Employee Benefits and Share-Based Compensation	12 Months Ended
	Dec. 31, 2020
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Benefits and Share-Based Compensation	11. Employee Benefits and Share-Based Compensation Amended and Restated 2013 Performance Incentive Plan In January 2013, NCLH adopted the 2013 Performance Incentive Plan, which provided for the issuance of up to 15,035,106 of NCLH’s ordinary shares pursuant to awards granted under the plan, with no more than 5,000,000 shares being granted to one individual in any calendar year. In May 2016, the plan was amended and restated (“Restated 2013 Plan”) pursuant to approval from the Board of Directors and NCLH’s shareholders. Among other things, under the Restated 2013 Plan, the number of NCLH’s ordinary shares that may be delivered pursuant to all awards granted under the plan was increased by an additional 12,430,000 shares to a new maximum aggregate limit of 27,465,106 shares. Additionally, the expiration date of the Restated 2013 Plan was extended to March 30, 2026. Share options under the plan are granted with an exercise price equal to the closing market price of NCLH shares at the date of grant. The vesting period for time-based options is typically set at three , four or five years with a contractual life ranging from seven to 10 years . The vesting period for time-based and performance-based restricted share units is generally three years . Forfeited awards will be available for subsequent awards under the Restated 2013 Plan. NCLH Share Option Awards There were no time-based share option awards granted for the years ended December 31, 2020, 2019 and 2018 or performance-based share option awards granted The estimated fair value of the share options is amortized over the requisite service period using the straight-line method. The assumptions used within the option-pricing model for the performance-based awards are as follows: ​ ​ ​ ​ 2018 Dividend yield —% Expected share price volatility 31.50% - 32.20% Risk-free interest rate 2.48% - 2.58% Expected term 3.72 - 4.22 years ​ Expected volatility was determined based on the historical share prices in our industry. The risk-free rate was based on U.S. Treasury zero coupon issues with a remaining term equal to the expected option term at grant date. The expected term was calculated under the simplified method. The following table sets forth a summary of option activity under NCLH’s Restated 2013 Plan for the period presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Number of Share Option Awards ​ Weighted-Average Exercise Price ​ Average ​ Aggregate ​ Time- Performance- Market- Time- Performance- Market- Contractual Intrinsic ​ ​ Based ​ Based ​ Based ​ Based ​ Based ​ Based ​ Term ​ Value ​ ​ Awards ​ Awards ​ Awards ​ Awards ​ Awards ​ Awards ​ (years) ​ (in thousands) Outstanding as of January 1, 2020 4,918,554 115,489 208,333 ​ $ 51.84 ​ $ 59.11 ​ $ 59.43 5.42 ​ $ 33,413 Exercised (48,221) ​ (906) — ​ ​ 44.38 ​ ​ 19.00 ​ ​ — ​ Forfeited and cancelled (345,126) ​ — — ​ ​ 51.24 ​ ​ — ​ ​ — ​ Outstanding as of December 31, 2020 4,525,207 114,583 208,333 ​ $ 51.96 ​ $ 59.43 ​ $ 59.43 4.42 ​ $ — Vested and expected to vest as of December 31, 2020 4,525,207 114,583 — ​ $ 51.96 ​ $ 59.43 ​ $ — 4.42 ​ $ — Exercisable as of December 31, 2020 4,525,207 114,583 — ​ $ 51.96 ​ $ 59.43 ​ $ — 4.42 ​ $ — ​ The weighted-average grant-date fair value of performance-based options granted (or where a grant date had not been previously established, the fair value recognized) during the year ended December 31, 2018 was $15.20. The total intrinsic value of share options exercised during 2020, 2019 and 2018 was $0.6 million, $13.3 million and $16.7 million, respectively, and total cash received by the Company from exercises was $2.2 million, $28.3 million and $25.8 million, respectively. As of December 31, 2020, there was no unrecognized compensation cost, related to options granted under our share-based incentive plans. Restricted Share Unit (“RSU”) Awards On July 27, 2020, NCLH granted 2.5 million time-based RSU awards to our employees, which vest on July 27, 2022. Additionally, on July 27, 2020, NCLH granted 0.3 million performance-based RSU awards to certain members of our management team, which vest upon the achievement of certain non-financial performance hurdles and generally require continued employment through July 27, 2022. On March 2, 2020, NCLH granted to certain employees 2.4 million time-based RSU awards which vest equally over three years . Also on March 2, 2020, NCLH granted to certain members of our management team 0.6 million performance-based RSU awards, which vest upon the achievement of certain pre-established performance targets and which amount assumes the maximum level of achievement. The fair value of the time-based and performance-based RSUs is equal to the closing market price of NCLH shares at the date of grant. The performance-based RSUs awarded to certain members of our management team are subject to performance conditions such that the number of shares that ultimately vest depends on the Adjusted EPS and Adjusted ROIC achieved by the Company during the performance period compared to targets established at the award date or other non-financial targets. Although the terms of the performance-based RSU awards provide the compensation committee with the discretion to make certain adjustments to the performance calculation, a mutual understanding of the key terms and conditions of these awards has been ascertained. NCLH remeasures the probability and the cumulative share-based compensation expense of the awards each reporting period until vesting or forfeiture occurs. The following table sets forth a summary of RSU activity for the period presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Weighted- Number of Weighted- Number of Weighted- ​ ​ Time-Based ​ Average Grant ​ Performance- ​ Average Grant ​ Market- ​ Average Grant ​ ​ Awards ​ Date Fair Value ​ Based Awards ​ Date Fair Value ​ Based Awards ​ Date Fair Value Non-vested as of January 1, 2020 ​ 3,245,625 ​ $ 54.94 ​ 1,129,396 ​ $ 56.09 ​ 50,000 ​ $ 59.43 Granted 5,380,123 ​ ​ 23.69 945,598 (1) ​ 27.75 — ​ ​ — Vested (1,610,315) ​ ​ 54.01 (192,523) ​ ​ 56.27 — ​ ​ — Forfeited or expired (351,508) ​ ​ 43.53 (317,287) ​ ​ 53.72 — ​ ​ — Non-vested as of December 31, 2020 6,663,925 ​ $ 30.54 1,565,184 ​ $ 39.42 50,000 ​ $ 59.43 Non-vested and expected to vest as of December 31, 2020 ​ 6,663,925 ​ $ 30.54 981,098 ​ $ 41.71 — ​ $ — (1) Number of performance-based RSU awards included assumes maximum achievement of performance targets. As of December 31, 2020, there were total unrecognized compensation costs related to non-vested time-based, non-vested performance-based and market-based RSUs of $127.8 million, $6.1 million and $0, respectively. The costs are expected to be recognized over a weighted-average period of 1.7 years, 1.0 years and 0 years , respectively, for the time-based, performance-based and market-based RSUs. Taxes paid pursuant to net share settlements in 2020, 2019 and 2018 were $15.4 million, $20.9 million and $13.9 million, respectively. Employee Stock Purchase Plan (“ESPP”) In April 2014, NCLH’s shareholders approved the ESPP. The purpose of the ESPP is to provide eligible employees with an opportunity to purchase NCLH’s ordinary shares at a favorable price and upon favorable terms in consideration of the participating employees’ continued services. A maximum of 2,000,000 of NCLH’s ordinary shares may be purchased under the ESPP. To be eligible to participate in an offering period, on the grant date of that period, an individual must be customarily employed by the Company or a participating subsidiary for more than twenty hours per week and for more than five months per calendar year. Participation in the ESPP is also subject to certain limitations. The ESPP is considered to be compensatory based on: a) the 15% purchase price discount and b) the look-back purchase price feature. Since the plan is compensatory, compensation expense must be recorded in the consolidated statements of operations on a straight-line basis over the six-month withholding period. As of December 31, 2020 and 2019, we had a liability for payroll withholdings received of $1.4 million and $2.1 million, respectively. The compensation expense recognized for share-based compensation for the periods presented include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Classification of expense 2020 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payroll and related (1) ​ $ 21,190 ​ $ 17,597 ​ $ 15,629 Marketing, general and administrative (2) ​ 90,107 ​ 77,458 ​ 100,354 Total share-based compensation expense ​ $ 111,297 ​ $ 95,055 ​ $ 115,983 (1) Amounts relate to equity granted to certain of our shipboard officers. (2) Amounts relate to equity granted to certain of our corporate employees. Employee Benefit Plans We offer annual incentive bonuses pursuant to our Restated 2013 Plan for our executive officers and other key employees. Bonuses under the plan become earned and payable based on NCLH’s performance during the applicable performance period and the individual’s continued employment. Company performance criteria include the attainment of certain financial targets and other strategic objectives. Certain employees are employed pursuant to agreements that provide for severance payments. Severance is generally only payable upon an involuntary termination of the employment by us without cause or a termination by the employee for good reason. Severance generally includes a series of cash payments based on the employee’s base salary and our payment of the employee’s continued medical benefits for the applicable severance period. We maintain a 401(k) Plan for our shoreside employees, including our executive officers. Participants may contribute up to 100% of eligible compensation each pay period, subject to certain limitations. In the past, we made matching contributions equal to 100% of the first 3% and 50% of amounts greater than 3% to and including 10% of each participant’s contributions subject to certain limitations. In addition, we may make discretionary supplemental contributions to the 401(k) Plan, which shall be allocated pro rata to each eligible participant based on the compensation of the participant relative to the total compensation of all participants. Our matching contributions are vested according to a five-year schedule. Due to the COVID-19 pandemic, we paused our matching contributions under the 401(k) Plan until further notice. The 401(k) Plan is subject to the provisions of ERISA and is intended to be qualified under section 401(a) of the U.S. Internal Revenue Code (the “Code”). Our matching contributions are reduced by amounts forfeited by those employees who leave the 401(k) Plan prior to vesting fully in the matching contributions. Forfeited contributions of $0.2 million, $0.2 million and $0.3 million were utilized in the years ended December 31, 2020, 2019 and 2018, respectively. We recorded total expenses related to the above 401(k) Plan of $2.8 million, $9.1 million and $9.3 million for the years ended December 31, 2020, 2019 and 2018, respectively. Effective January 2009, we implemented the Shipboard Retirement Plan which computes benefits based on years of service, subject to eligibility requirements. The Shipboard Retirement Plan is unfunded with no plan assets. The current portion of the projected benefit obligation of $0.9 million was included in accrued expenses and other liabilities as of December 31, 2020 and 2019, and $30.7 million and $27.8 million was included in other long-term liabilities in our consolidated balance sheets as of December 31, 2020 and 2019, respectively. The amounts related to the Shipboard Retirement Plan were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of or for the Year Ended December 31, ​ 2020 2019 2018 Pension expense: ​ ​ ​ Service cost ​ $ 2,665 ​ $ 2,135 ​ $ 2,167 Interest cost ​ 895 ​ 1,001 ​ 857 Amortization of prior service cost ​ 378 ​ 378 ​ 378 Amortization of actuarial loss ​ 29 ​ — ​ 51 Total pension expense ​ $ 3,967 ​ $ 3,514 ​ $ 3,453 Change in projected benefit obligation: ​ ​ ​ Projected benefit obligation at beginning of year ​ $ 28,695 ​ $ 24,318 ​ $ 24,587 Service cost ​ 2,665 ​ 2,135 ​ 2,167 Interest cost ​ 895 ​ 1,001 ​ 857 Actuarial (gain) loss ​ 62 ​ 2,308 ​ (2,271) Direct benefit payments ​ (698) ​ (1,067) ​ (1,022) Projected benefit obligation at end of year ​ $ 31,619 ​ $ 28,695 ​ $ 24,318 Amounts recognized in the consolidated balance sheets: ​ ​ ​ Projected benefit obligation ​ $ 31,619 ​ $ 28,695 ​ $ 24,318 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended December 31, ​ 2020 2019 2018 Amounts recognized in accumulated other comprehensive income (loss): ​ ​ ​ Prior service cost ​ $ (3,403) ​ $ (3,781) ​ $ (4,159) Accumulated actuarial loss ​ (3,446) ​ (3,413) ​ (1,105) Accumulated other comprehensive income (loss) ​ $ (6,849) ​ $ (7,194) ​ $ (5,264) ​ The discount rates used in the net periodic benefit cost calculation for the years ended December 31, 2020, 2019 and 2018 were 3.2%, 4.2% and 3.6%, respectively, and the actuarial loss is amortized over 18.57 years. The discount rate is used to measure and recognize obligations, including adjustments to other comprehensive income (loss), and to determine expense during the periods. It is determined by using bond indices which reflect yields on a broad maturity and industry universe of high-quality corporate bonds. The pension benefits expected to be paid in each of the next five years and in aggregate for the five years thereafter are as follows (in thousands): ​ ​ ​ ​ Year Amount 2021 ​ $ 918 2022 ​ ​ 989 2023 ​ ​ 1,118 2024 ​ ​ 1,224 2025 ​ ​ 1,339 Next five years ​ ​ 11,004 ​

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes We are incorporated in Bermuda. Under current Bermuda law, we are not subject to tax on income and capital gains. We have received from the Minister of Finance under The Exempted Undertakings Tax Protection Act 1966, as amended, an assurance that, in the event that Bermuda enacts legislation imposing tax computed on profits, income, any capital asset, gain or appreciation, or any tax in the nature of estate duty or inheritance, then the imposition of any such tax shall not be applicable to us or to any of our operations or shares, debentures or other obligations, until March 31, 2035. For the taxable years ended 2020, 2019 and 2018, NCLC was treated as a disregarded entity for U.S. federal income tax purposes and will be going forward. Two of NCLC’s subsidiaries file a U.S. federal income tax return. The components of net income before income taxes consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Bermuda ​ $ — ​ $ — ​ $ — Foreign - Other ​ (4,986,613) ​ ​ 914,001 ​ ​ 974,172 Net income (loss) before income taxes ​ $ (4,986,613) ​ $ 914,001 ​ $ 974,172 ​ The components of the provision for income taxes consisted of the following benefit (expense) (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Current: ​ ​ ​ Bermuda ​ $ — ​ $ — ​ $ — United States ​ (326) ​ 837 ​ (836) Foreign - Other ​ (5,502) ​ (6,294) ​ (5,371) Total current: ​ (5,828) ​ (5,457) ​ (6,207) Deferred: ​ ​ ​ Bermuda ​ — ​ — ​ — United States ​ (15,613) ​ 32,315 ​ (2,001) Foreign - Other ​ (129) ​ 347 ​ 226 Total deferred: ​ (15,742) ​ 32,662 ​ (1,775) Income tax benefit (expense) ​ $ (21,570) ​ $ 27,205 ​ $ (7,982) ​ Our reconciliation of income tax expense computed by applying our Bermuda statutory rate and reported income tax benefit (expense) was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Tax at Bermuda statutory rate ​ $ — ​ $ — ​ $ — Foreign income taxes at different rates ​ 17,051 ​ (9,819) ​ (11,119) Tax contingencies ​ (626) ​ (206) ​ (6) Return to provision adjustments ​ 9 ​ 1,538 ​ 3,055 Benefit (expense) from change in tax rate ​ — ​ (7) ​ 88 Valuation allowance ​ (38,004) ​ 35,699 ​ — Income tax benefit (expense) ​ $ (21,570) ​ $ 27,205 ​ $ (7,982) ​ Deferred tax assets and liabilities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2020 2019 Deferred tax assets: ​ ​ ​ Loss carryforwards ​ $ 77,093 ​ $ 54,122 Other ​ 4,561 ​ 2,356 Valuation allowance ​ (42,876) ​ (5,847) Total net deferred assets ​ 38,778 ​ 50,631 Deferred tax liabilities: ​ ​ Property and equipment ​ (36,463) ​ (34,724) Total deferred tax liabilities ​ (36,463) ​ (34,724) Net deferred tax asset (liability) ​ $ 2,315 ​ $ 15,907 ​ We have U.S. net operating loss carryforwards of $352.9 million and $238.8 million for the years ended December 31, 2020 and 2019, respectively, which begin to expire in 2030, a portion of which relate to Prestige discussed further below. We evaluate our deferred tax assets each period to determine if a valuation allowance is required based on whether it is more likely than not that some portion of the deferred tax assets would not be realized. The ultimate realization of these deferred tax assets is dependent upon the generation of sufficient taxable income during future periods. We conduct our evaluation by considering all available positive and negative evidence. This evaluation considers, among other factors, historical operating results, forecasts of future profitability, the duration of statutory carryforward periods, and the outlooks for the cruise industry and broader economy. Based on the weight of available evidence, we have recorded a valuation allowance during the fourth quarter of 2020 in the amount of $39.6 million with respect to the U.S. net deferred tax assets in one of our U.S. and several of our foreign subsidiaries. Included above are deferred tax assets associated with our operations in Norway for which we have provided a full valuation allowance. We have Norway net operating loss carryforwards of $13.4 million and $13.3 million for the years ended December 31, 2020 and 2019, respectively, which can be carried forward indefinitely. Included above are deferred tax assets associated with our branch operations in the U.K. for which we have provided a full valuation allowance. We had U.K. net operating loss carryforwards of $5.5 million for the year ended December 31, 2019; however, there are no outstanding net loss carryforwards as of December 31, 2020. Included above are deferred tax assets associated with Prestige. We have U.S. net operating loss carryforwards of $155.0 million and $145.0 million for the years ended December 31, 2020 and 2019, respectively, which begin to expire in 2030 . Utilization of the Prestige net operating loss carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred previously and/or that could occur in the future, as provided by Section 382 of the Internal Revenue Code of 1986 (“Section 382”). Ownership changes may limit the amount of net operating loss carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period. If we have experienced an ownership change, utilization of Prestige’s net operating loss carryforwards would be subject to an annual limitation under Section 382. Any limitation may result in expiration of a portion of the net operating loss carryforwards before utilization. Subsequent ownership changes could further impact the limitation in future years. We implemented certain tax restructuring strategies that created our ability to utilize the net operating loss carryforwards of Prestige, for which we had previously provided a full valuation allowance. During the first quarter of 2019, we completed a Section 382 study that determined the amount of the Prestige net operations loss carryforwards that could be utilized against future taxable income resulting in a tax benefit of The following is a tabular reconciliation of the total amounts of unrecognized tax benefits (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2020 2019 Unrecognized tax benefits, beginning of the year ​ $ 732 ​ $ 532 Gross increases in tax positions from prior periods ​ 620 ​ 200 Unrecognized tax benefits, end of year ​ $ 1,352 ​ $ 732 ​ If the $1.4 million of unrecognized tax benefits at December 31, 2020 were recognized, our effective tax rate would be minimally affected. We believe that there will not be a significant increase or decrease to the tax positions within 12 months of the reporting date. We recognize interest and penalties related to unrecognized tax benefits in income tax benefit (expense). We file income tax returns in the U.S. federal jurisdiction, various U.S. state jurisdictions and foreign jurisdictions. We are generally no longer subject to U.S. federal, state and local, or non-U.S. income tax examinations by authorities for years prior to 2017, except for years in which NOLs generated prior to 2017 are utilized. Due to our international structure as well as the existence of international tax treaties that exempt taxation on certain activities, the repatriation of earnings from our subsidiaries would have no tax impact. We derive our income from the international operation of ships. We are engaged in a trade or business in the U.S. and receive income from sources within the U.S. Under Section 883, certain foreign corporations are exempt from U. S. federal income or branch profits tax on U.S.-source income derived from or incidental to the international operation of ships. Applicable U.S. treasury regulations provide that a foreign corporation will qualify for the benefits of Section 883 if, in relevant part: (i) the foreign country in which the corporation is organized grants an equivalent exemption for income from the international operation of ships to corporations organized in the U.S., and (ii) the foreign corporation has one or more classes of stock that are “primarily and regularly traded on an established securities market” in the U.S. or another qualifying country. We believe that we qualify for the benefits of Section 883 because we are incorporated in qualifying countries and our ordinary shares are primarily and regularly traded on an established securities market in the U.S.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies Ship Construction Contracts For the Norwegian brand, Project Leonardo will introduce six additional ships, each ranging from approximately 140,000 to 156,300 Gross Tons with approximately 3,300 to 3,550 Berths, with expected delivery dates from 2022 through 2027. For the Regent brand, we have one Explorer Class Ship on order to be delivered in 2023 For the Oceania Cruises brand, we have orders for two Allura Class Ships to be delivered in 2023 and 2025. Each of the Allura Class Ships will be approximately 67,000 Gross Tons and 1,200 Berths. The impacts of COVID-19 on the shipyards where our ships are under construction (or will be constructed) have resulted in some delays in expected ship deliveries, and the impacts of COVID-19 could result in additional delays in ship deliveries in the future, which may be prolonged. The combined contract prices of the nine ships on order for delivery was approximately €7.1 billion, or $8.7 billion based on the euro/U.S. dollar exchange rate as of December 31, 2020. We have obtained export credit financing for the ships on order which is expected to fund approximately 80% of each contract price, subject to certain conditions. We do not anticipate any contractual breaches or cancellation to occur. However, if any such events were to occur, it could result in, among other things, the forfeiture of prior deposits or payments made by us and potential claims and impairment losses which may materially impact our business, financial condition and results of operations. As of December 31, 2020, minimum annual payments for non-cancelable ship construction contracts with initial or remaining terms in excess of one year were as follows (in thousands): ​ ​ ​ ​ ​ Year Amount 2021 ​ $ 463,549 2022 ​ 1,118,430 2023 ​ 2,168,127 2024 ​ 1,092,766 2025 ​ 1,758,314 Thereafter ​ 1,870,807 Total minimum annual payments ​ $ 8,471,993 ​ Subsequent to December 31, 2020, $194.1 million of payments anticipated in 2021 have been deferred and we have a memorandum of agreement in place to finance another $35.2 million. Port Facility Commitments As of December 31, 2020, future commitments to pay for usage of certain port facilities were as follows (in thousands): ​ ​ ​ ​ ​ Year Amount 2021 ​ $ 71,691 2022 ​ 71,296 2023 ​ 71,460 2024 ​ 75,822 2025 ​ 70,132 Thereafter ​ 1,707,376 Total port facility future commitments ​ $ 2,067,777 ​ Our port facilities agreements generally include force majeure provisions that may alleviate an unspecified amount of obligations under minimum guarantees during the COVID-19 pandemic. In 2020, the Company provided the required notice that such provisions were being enacted. Customary practice is to prorate these obligations for the annual period impacted. Other Commitments The FMC requires evidence of financial responsibility for those offering transportation on passenger ships operating out of U.S. ports to indemnify passengers in the event of non-performance of the transportation. Accordingly, each of our three brands are required to maintain a $32.0 million third-party performance guarantee in respect of liabilities for non-performance of transportation and other obligations to passengers. The guarantee requirements are subject to additional consumer price index-based adjustments. In addition, our brands have a legal requirement to maintain security guarantees based on cruise business originated from the U.K., and we are required to establish financial responsibility by certain jurisdictions to meet liability in the event of non-performance of our obligations to passengers from those jurisdictions. As of December 31, 2020, we have in place approximately From time to time, various other regulatory and legislative changes have been or may in the future be proposed that may have an effect on our operations in the U.S. and the cruise industry in general. Litigation Class Actions On March 12, 2020, a class action complaint, Eric Douglas v. Norwegian Cruise Lines, Frank J. Del Rio and Mark A. Kempa, Case No. 1:20-CV-21107, was filed in the United States District Court for the Southern District of Florida, naming the Company, Frank J. Del Rio, the Company’s President and Chief Executive Officer, and Mark A. Kempa, the Company’s Executive Vice President and Chief Financial Officer, as defendants. Subsequently, two similar class action complaints were also filed in the United States District Court for the Southern District of Florida naming the same defendants. On July 31, 2020, a consolidated amended class action complaint was filed by lead plaintiff’s counsel. The complaint asserts claims, purportedly brought on behalf of a class of shareholders, under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, and Rule 10b-5 promulgated thereunder, and allege that the Company made false and misleading statements to the market and customers about COVID-19. The complaint seeks unspecified damages and an award of costs and expenses, including reasonable attorneys’ fees, on behalf of a purported class of purchasers of our ordinary shares between February 20, 2020 and March 10, 2020. We believe that the allegations contained in the complaint are without merit and intend to defend the complaint vigorously. We cannot predict at this point the length of time that this action will be ongoing or the liability, if any, which may arise therefrom. In addition, in March 2020 the Florida Attorney General announced an investigation related to the Company’s marketing during the COVID-19 pandemic. Following the announcement of the investigation by the Florida Attorney General, we received notifications from other attorneys general and governmental agencies that they are conducting similar investigations. The Company is cooperating with these ongoing investigations, the outcomes of which cannot be predicted at this time. Helms-Burton Act On August 27, 2019, two lawsuits were filed against Norwegian Cruise Line Holdings Ltd. in the United States District Court for the Southern District of Florida under Title III of the Cuban Liberty and Solidarity (Libertad) Act of 1996, also known as the Helms-Burton Act. The complaint filed by Havana Docks Corporation alleges it holds an interest in the Havana Cruise Port Terminal and the complaint filed by Javier Garcia-Bengochea alleges that he holds an interest in the Port of Santiago, Cuba, both of which were expropriated by the Cuban Government. The complaints further allege that the Company “trafficked” in those properties by embarking and disembarking passengers at these facilities. The plaintiffs seek all available statutory remedies, including the value of the expropriated property, plus interest, treble damages, attorneys’ fees and costs. On January 7, 2020, the United States District Court for the Southern District of Florida dismissed the claim by Havana Docks Corporation. On April 14, 2020, the district court granted Havana Docks Corporation’s motion to reconsider and vacated its order dismissing the claim, allowing Havana Docks Corporation to file an amended complaint on April 16, 2020. On April 24, 2020, we filed a motion seeking permission to appeal the district court’s order which was subsequently denied. On September 1, 2020, the Court entered an order staying all case deadlines and administratively closed the Garcia-Bengochea matter pending the outcome of the appeal in a related case brought by the same plaintiff. We believe we have meritorious defenses to the claims and intend to vigorously defend these matters. As of December 31, 2020, we are unable to reasonably estimate any potential contingent loss from these matters. ​ Other ​ In the normal course of our business, various other claims and lawsuits have been filed or are pending against us. Most of these claims and lawsuits are covered by insurance and, accordingly, the maximum amount of our liability is typically limited to our deductible amount. Nonetheless, the ultimate outcome of these claims and lawsuits that are not covered by insurance cannot be determined at this time. We have evaluated our overall exposure with respect to all of our threatened and pending litigation and, to the extent required, we have accrued amounts for all estimable probable losses associated with our deemed exposure. We are currently unable to estimate any other potential contingent losses beyond those accrued, as discovery is not complete nor is adequate information available to estimate such range of loss or potential recovery. However, based on our current knowledge, we do not believe that the aggregate amount or range of reasonably possible losses with respect to these matters will be material to our consolidated results of operations, financial condition or cash flows. We intend to vigorously defend our legal position on all claims and, to the extent necessary, seek recovery. ​ Other Contingencies The Company also has agreements with its credit card processors that govern approximately $1.0 billion at December 31, 2020 in advance ticket sales that have been received by the Company relating to future voyages. These agreements allow the credit card processors to require under certain circumstances, including the existence of a material adverse change, excessive chargebacks and other triggering events, that the Company maintain a reserve which would be satisfied by posting collateral. Although the agreements vary, these requirements may generally be satisfied either through a percentage of customer payments withheld or providing cash funds directly to the card processor. Any cash reserve or collateral requested could be increased or decreased. As of December 31, 2020, we had a reserve of approximately $200 million with a credit card processor recognized in other long-term assets, and in January 2021, we provided additional cash collateral of $250 million. Additionally, we are required to fund all refunds until further notice and 100% of incoming advance ticket sales deposits with this credit card processor will be withheld and are not expected to be released until the credit card processor’s exposure is fully collateralized. As of December 31, 2020, the exposure was approximately $780 million. The reserve shortfall of approximately $330 million, after taking into effect the January additional collateral provided, will decrease as refunds are funded, cruises are provided and amounts withheld by the credit card processor are allocated to the reserve rather than remitted to the Company. We may be required to find new credit card processors, pledge additional collateral and/or post cash reserves or take other actions that may further reduce our liquidity.

Other Income (Expense), Net

Other Income (Expense), Net	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Other Income (Expense), Net	14. Other Income (Expense), Net Other income (expense), net was expense of $984.5 million, income of $6.2 million, and income of $20.7 million for the years ended December 31, 2020, 2019 and 2018, respectively. In 2020, the expense was primarily due to losses from conversion options

Concentration Risk

Concentration Risk	12 Months Ended
	Dec. 31, 2020
Risks and Uncertainties [Abstract]
Concentration Risk	15. Concentration Risk We contract with a single vendor to provide many of our hotel and restaurant services including both food and labor costs. We incurred expenses of $59.0 million, $153.6 million and $153.7 million for the years ended December 31, 2020, 2019 and 2018, respectively, which are recorded in payroll and related in our consolidated statements of operations.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	16. Supplemental Cash Flow Information For the year ended December 31, 2020, we had non-cash investing activities related to property and equipment of $17.7 million. Additionally, we received seller financing related to the acquisition of property and equipment resulting in both non-cash investing and financing activities of $11.9 million. For the year ended December 31, 2020, we paid income taxes of $2.9 million and interest and related fees, net of capitalized interest, of $447.9 million. For the year ended December 31, 2019, we had non-cash investing activities related to property and equipment of $8.2 million For the year ended December 31, 2019, we paid income taxes of $8.7 million and interest and related fees, net of capitalized interest, of $291.2 million. For the year ended December 31, 2018, we had non-cash investing activities in connection with property and equipment of $39.7 million and net foreign currency adjustments of $5.5 million related to euro-denominated debt related to the financing of two of our Project Leonardo ships. For the year ended December 31, 2018, we paid income taxes of $10.0 million and interest and related fees, net of capitalized interest, of $350.4 million.

Quarterly Selected Financial Da

Quarterly Selected Financial Data (Unaudited) (in thousands)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Selected Financial Data (Unaudited) (in thousands)	17. Quarterly Selected Financial Data (Unaudited) (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ First Quarter ​ Second Quarter ​ Third Quarter ​ Fourth Quarter ​ 2020 2019 2020 2019 2020 2019 2020 2019 Total revenue ​ $ 1,246,882 ​ $ 1,403,630 ​ $ 16,929 ​ $ 1,664,277 ​ $ 6,518 ​ $ 1,913,851 ​ $ 9,579 ​ $ 1,480,618 Operating income (loss) ​ $ (1,823,279) ​ $ 158,904 ​ $ (594,537) ​ $ 309,594 ​ $ (517,478) ​ $ 512,337 ​ $ (546,755) ​ $ 199,878 Net income (loss) ​ $ (1,882,266) ​ $ 119,404 ​ $ (951,065) ​ $ 243,276 ​ $ (758,152) ​ $ 455,309 ​ $ (1,416,700) ​ $ 123,217 ​ The seasonality of the North American cruise industry generally results in the greatest demand for cruises during the Northern Hemisphere’s summer months; however, our cruise voyages were completely suspended during the last nine months of 2020 due to the COVID-19 pandemic.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	18. Subsequent Events In January and February 2021, both NCLH and NCLC undertook a number of actions related to debt financing, which resulted in a reclassification of debt from short-term to long-term as of December 31, 2020, and are described in Note 8 – “Long-Term Debt”.

Schedule II Valuation and Quali

Schedule II Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II Valuation and Qualifying Accounts	NCL Corporation Ltd. Schedule II Valuation and Qualifying Accounts (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Additions ​ ​ ​ ​ ​ ​ ​ ​ ​ Charged to ​ ​ ​ ​ ​ ​ ​ ​ Balance ​ costs and ​ Charged to ​ ​ ​ ​ Balance Description ​ 12/31/17 ​ expenses ​ other accounts ​ Deductions (a) ​ 12/31/18 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation allowance on deferred tax assets ​ $ 42,154 ​ $ — ​ $ 276 ​ $ (506) ​ $ 41,924 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Charged to ​ ​ ​ ​ ​ ​ ​ ​ Balance ​ costs and ​ Charged to ​ ​ ​ ​ Balance Description ​ 12/31/18 ​ expenses ​ other accounts ​ Deductions (a) ​ 12/31/19 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation allowance on deferred tax assets ​ $ 41,924 ​ $ — ​ $ — ​ $ (36,077) ​ $ 5,847 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Charged to Charged to ​ ​ ​ ​ ​ ​ Balance ​ costs and ​ other ​ ​ ​ ​ Balance Description ​ 12/31/19 ​ expenses ​ accounts (b) ​ Deductions (a) ​ 12/31/20 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Valuation allowance on deferred tax assets ​ $ 5,847 ​ $ — ​ $ 38,150 ​ $ (1,121) ​ $ 42,876 (a) Amount relates to (i) utilization of deferred tax assets, (ii) revaluation of deferred tax assets from their functional currency to U.S. dollars and (iii) reversal of valuation allowances. (b) Amount relates to a valuation allowance on net U.S. deferred tax assets.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Liquidity and Management’s Plan Due to the continued spread of COVID-19, growing travel restrictions and limited access to ports around the world, in March 2020, the Company implemented a voluntary suspension of all cruise voyages across its three brands. As of the date of this filing and through at least May 31, 2021, all cruise voyages remain suspended. Significant events affecting travel, including COVID-19, typically have an impact on demand for cruise vacations, with the full extent of the impact generally determined by the length of time the event influences travel decisions. We believe the ongoing effects of COVID-19 on our operations and global bookings have had, and will continue to have, a significant impact on our financial results and liquidity, and such negative impact may continue well beyond the containment of the pandemic. We continue to expect a gradual phased relaunch of our ships after the voyage suspension period, with our ships initially operating at reduced occupancy levels. The timing for bringing our ships back to service and the percentage of our fleet in service will depend on a number of factors including, but not limited to, the duration and extent of the COVID-19 pandemic, further resurgences and new variants of COVID-19, the availability, distribution, and efficacy of vaccines and therapeutics for COVID-19, our ability to comply with governmental regulations, port availability, travel restrictions, bans and advisories, and our ability to re-staff our ships and implement new health and safety protocols. The estimation of our future cash flow projections includes numerous assumptions that are subject to various risks and uncertainties. Upon the relaunch of cruise voyages, our principal assumptions for future cash flow projections include: ● Expected gradual phased relaunch at reduced occupancy levels; ● Forecasted cash collections primarily upon completion of future voyages and the payment of cash refunds for any further cancellations, in accordance with the terms of our credit card processing agreements (see Note 13 - “Commitments and Contingencies”); and ● Expected incremental expenses for resumption of cruise voyages, including the maintenance of and compliance with additional health and safety protocols. Due to the unknown duration and extent of the COVID-19 pandemic, travel restrictions, bans and advisories, uncertainties around our ability to comply with governmental regulations, the potential unavailability of ports and/or destinations, voyage cancellations and timing of redeployments, and a general impact on consumer sentiment regarding cruise travel, we cannot predict when we will relaunch voyages or when our full fleet will be back in service at historical occupancy levels. Until we are able to begin our phased relaunch, our projected liquidity requirements reflect our principal assumptions surrounding ongoing operating costs during the suspension of cruise voyages, as well as liquidity requirements for financing costs and necessary capital expenditures, and our ability to continue to implement cash conservation strategies, including, but not limited to: ● Moving our ships to minimum manning levels, which we expect would result in further reductions in crew payroll costs, fuel consumption, and maintenance costs; ● Further reductions in general operating expenses; and ● Further reductions in discretionary capital expenditures including cancellation or reduction in scope of certain Dry-docks. Subsequent to December 31, 2020 further actions, including debt principal payment deferrals and deferral of ship milestone payments, were taken to bolster our financial condition. See Note 8 – “Long-Term Debt” and Note 13 - “Commitments and Contingencies” disclosure for further information. We cannot make assurances that our assumptions used to estimate our liquidity requirements may not change because we have never experienced a complete cessation of our cruise voyages. Accordingly, the full effect of our suspension of cruise voyages on our financial performance and financial condition cannot be quantified at this time. We have made reasonable estimates and judgments of the impact of COVID-19 within our financial statements and there may be material changes to those estimates in future periods. We expect to report a net loss for at least the quarter ending March 31, 2021, and likely expect to report a net loss until we are able to resume voyages, including for the year ending December 31, 2021. Based on these actions and assumptions regarding the impact of COVID-19, and considering our available liquidity including cash and cash equivalents of $3.3 billion at December 31, 2020, we have concluded that after implementing the above cash conservation strategies, we have sufficient liquidity to satisfy our obligations for at least the next twelve months even in the event we do not resume cruise voyages during that period. Subsequent to the liquidity assessment period (twelve months from the issuance of these financial statements), the Company will require additional liquidity to meet ongoing obligations, including debt amortization payments and ship milestone payments, of approximately $560 million that are due in April 2022, in order to maintain its minimum liquidity covenant requirements. The Company plans to take additional steps following the issuance of these financial statements to increase its liquidity, which may include additional debt and/or equity financing and potential further renegotiations of its debt amortization payments, newbuild payments and covenants. The extent of these actions to increase the Company’s liquidity will be dependent in part on the timing of the resumption of cruise voyages, which is uncertain. There can be no assurances that the Company will be successful in generating the additional liquidity necessary to meet its obligations beyond twelve months from the issuance of these financial statements on terms acceptable to the Company or at all. If the Company is unable to maintain or renegotiate its minimum liquidity covenant requirements, it could have a significant adverse effect on the Company’s business, financial condition and operating results. Basis of Presentation Our consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America and contain all normal recurring adjustments necessary for a fair presentation of the results for the periods presented. Estimates are required for the preparation of consolidated financial statements in accordance with generally accepted accounting principles and actual results could differ from these estimates. All significant intercompany accounts and transactions are eliminated in consolidation.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents are stated at cost and include cash and investments with original maturities of three months or less at acquisition and also include amounts due from credit card processors that are not subject to holdbacks.
Accounts Receivable, Net	Accounts Receivable, Net Accounts receivable are shown net of an allowance for credit losses of $35.4 million and $10.6 million as of December 31, 2020 and 2019, respectively.
Inventories	Inventories Inventories mainly consist of provisions, supplies and fuel and are carried at the lower of cost or net realizable value using the first-in, first-out method of accounting.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred except for those that result in tangible assets, including brochures, which are treated as prepaid expenses and charged to expense as consumed. Advertising costs of $0.9 million and $5.9 million as of December 31, 2020 and 2019, respectively, are included in prepaid expenses and other assets. Expenses related to advertising costs totaled $216.5 million, $400.6 million and $327.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are recorded at cost. Ship improvement costs that we believe add value to our ships are capitalized to the ship and depreciated over the shorter of the improvements’ estimated useful lives or the remaining useful life of the ship while costs of repairs and maintenance, including Dry-dock costs, are charged to expense as incurred. During ship construction, certain interest is capitalized as a cost of the ship. Gains or losses on the sale of property and equipment are recorded as a component of operating income (expense) in our consolidated statements of operations. The useful lives of ship improvements are estimated based on the economic lives of the new components. In addition, to determine the useful lives of the ship or ship components, we consider the impact of the historical useful lives of similar assets, manufacturer recommended lives and anticipated changes in technological conditions. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, after a 15% reduction for the estimated residual values of ships as follows: ​ ​ ​ ​ ​ Useful Life Ships 30 years Computer hardware and software 3 Other property and equipment 3 Leasehold improvements Shorter of lease term or asset life Ship improvements Shorter of asset life or life of the ship ​ Long-lived assets are reviewed for impairment, based on estimated future undiscounted cash flows, whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Assets are grouped and evaluated at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other groups of assets. For ship impairment analyses, the lowest level for which identifiable cash flows are largely independent of other assets and liabilities is each individual ship. We consider historical performance and future estimated results in our evaluation of potential impairment and then compare the carrying amount of the asset to the estimated future cash flows expected to result from the use of the asset. If the carrying amount of the asset exceeds estimated expected undiscounted future cash flows, we measure the amount of the impairment by comparing the carrying amount of the asset to its estimated fair value. We estimate fair value based on the best information available utilizing estimates, judgments and projections as necessary. Our estimate of fair value is generally measured by discounting expected future cash flows at discount rates commensurate with the associated risk.
Goodwill and Trade Names	Goodwill and Trade Names Goodwill represents the excess of cost over the estimated fair value of net assets acquired. Goodwill and other indefinite-lived assets, principally trade names, are reviewed for impairment on December 31 or earlier if there is an event or change in circumstances that would indicate that the carrying value of these assets may not be fully recoverable. We use the Step 0 Test which allows us to first assess qualitative factors to determine whether it is more likely than not (i.e., more than 50%) that the estimated fair value of a reporting unit is less than its carrying value. For trade names we also provide a qualitative assessment to determine if there is any indication of impairment. In order to make this evaluation, we consider the following circumstances as well as others: ● Changes in general macroeconomic conditions such as a deterioration in general economic conditions; limitations on accessing capital; fluctuations in foreign exchange rates; or other developments in equity and credit markets; ● Changes in industry and market conditions such as a deterioration in the environment in which an entity operates; an increased competitive environment; a decline in market-dependent multiples or metrics (in both absolute terms and relative to peers); a change in the market for an entity’s products or services; or a regulatory or political development; ● Changes in cost factors that have a negative effect on earnings and cash flows; ● Decline in overall financial performance (for both actual and expected performance); ● Entity and reporting unit specific events such as changes in management, key personnel, strategy, or customers; litigation; or a change in the composition or carrying amount of net assets; and ● Decline in share price (in both absolute terms and relative to peers). We also may conduct a quantitative assessment comparing the estimated fair value of each reporting unit to its carrying value, including goodwill. This is called the Step 1 Test which uses discounted future cash flows and other market data to determine the estimated fair value of the reporting units. Our discounted cash flow valuation reflects our principal assumptions of 1) forecasted future operating results and growth rates, which have been prepared under multiple scenarios and are probability weighted, 2) forecasted capital expenditures for fleet growth and ship improvements and 3) a weighted average cost of capital of market participants. Historically, our Step 1 Test consisted of a combined approach using discounted future cash flows and market multiples to determine the estimated fair value of the reporting units. However, beginning with the Step 1 Test performed as of March 31, 2020 as a result of triggering events, the market multiples were used solely as a corroboratory approach given the impact of COVID-19 on the current year’s results, as of the valuation date, as well as prospective results including the lack of any guidance provided, which were not available for our peers. We believe that this approach is the most representative method to estimate fair value as it utilizes expectations of long-term growth as well as current market conditions. For the trade names, we use the relief from royalty method, which uses the same forecasts and discount rates from the discounted cash flow valuation in the goodwill assessment along with a trade name royalty rate assumption. ​ We have concluded that our business has three reporting units. Each brand, Oceania Cruises, Regent Seven Seas and Norwegian, constitutes a business for which discrete financial information is available and management regularly reviews the operating results and, therefore, each brand is considered an operating segment. During the year ended December 31, 2020, we recognized a goodwill impairment loss of $1.3 billion based on the impairment test performed as of March 31, 2020. See Note 4 – “Goodwill and Intangible Assets” for additional information. As of December 31, 2020, there was $98.1 million of goodwill remaining for the Regent Seven Seas reporting unit. We also recognized an impairment loss for our Oceania Cruises and Regent Seven Seas Cruises trade names in an aggregate amount of $317.0 million based on the March 31, 2020 impairment test, with $500.5 million remaining as of December 31, 2020. For our 2020 annual goodwill and trade name impairment evaluations, we elected to perform quantitative testing. Based on the results of the Step 1 Tests at December 31, 2020, we determined there was no further impairment of goodwill because the estimated fair value of the Regent Seven Seas reporting unit substantially exceeded the carrying value. We also determined there was no impairment to our trade names. We believe that we have made reasonable estimates and judgments. However, a change in our estimated future operating cash flows may result in a decline in estimated fair value in future periods, which may result in a need to recognize additional impairment charges.
Revenue and Expense Recognition	Revenue and Expense Recognition Deposits on advance ticket sales are deferred when received and are subsequently recognized as revenue ratably during the voyage sailing days as services are rendered over time on the ship. Cancellation fees are recognized in passenger ticket revenue in the month of the cancellation. Goods and services associated with onboard revenue are generally provided at a point in time and revenue is recognized when the performance obligation is satisfied. A receivable is recognized for onboard goods and services rendered when the voyage is not completed before the end of the period. All associated direct costs of a voyage are recognized as incurred in cruise operating expenses.
Disaggregation of Revenue	Disaggregation of Revenue Revenue and cash flows are affected by economic factors in various geographical regions. Revenues by destination consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 ​ 2018 North America ​ $ 960,258 ​ $ 3,807,576 ​ $ 3,543,282 Europe ​ 27,602 ​ 1,666,751 ​ 1,462,698 Asia-Pacific ​ 152,976 ​ 500,842 ​ 721,404 Other ​ 139,072 ​ 487,207 ​ 327,742 Total revenue ​ $ 1,279,908 ​ $ 6,462,376 ​ $ 6,055,126 ​
Segment Reporting	Segment Reporting We have concluded that our business has a single reportable segment. Each brand, Norwegian, Oceania Cruises and Regent, constitutes a business for which discrete financial information is available and management regularly reviews the brand level operating results and, therefore, each brand is considered an operating segment. Our operating segments have similar economic and qualitative characteristics, including similar long-term margins and similar products and services; therefore, we aggregate all of the operating segments into one reportable segment. Although we sell cruises on an international basis, our passenger ticket revenue is primarily attributed to U.S.-sourced guests who make reservations in the U.S. Revenue attributable to U.S.-sourced guests was 83%, 81% and 77% for the years ended December 31, 2020, 2019 and 2018, respectively. No other individual country’s revenues exceeded 10% in any of our last three years. Substantially all of our long-lived assets are located outside of the U.S. and consist primarily of our ships. We had 19 ships with Bahamas registry with a carrying value of $9.9 billion as of December 31, 2020 and $10.2 billion as of December 31, 2019. We had eight ships with Marshall Island registry with a carrying value of $2.4 billion as of December 31, 2020 and seven ships with Marshall Island registry with a carrying value of $1.9 billion as of December 31, 2019. We also had one ship with U.S. registry with a carrying value of $0.3 billion as of December 31, 2020 and 2019.
Debt Issuance Costs	Debt Issuance Costs Debt issuance costs related to a recognized debt liability are presented in the consolidated balance sheets as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. For line of credit arrangements and for those debt facilities not fully drawn we defer and present debt issuance costs as an asset. These deferred issuance costs are amortized over the life of the loan. The amortization of deferred financing fees is included in depreciation and amortization expense in the consolidated statements of cash flows; however, for purposes of the consolidated statements of operations it is included in interest expense, net.
Payment-in-Kind Interest	Payment-in-Kind Interest Payment-in-kind interest is recognized at the stated rate. On the contractual interest payment date, the related par value is recognized at its fair value with any difference between the carrying amount of the accrued interest and the fair value of the new debt recognized as an adjustment in interest expense, net. The amount of fair value that is attributable to a debt conversion option is bifurcated and recognized within exchangeable notes. In December 2020, we recognized a $19.3 million premium for payment-in-kind interest.
Foreign Currency	Foreign Currency The majority of our transactions are settled in U.S. dollars. Gains or losses resulting from transactions denominated in other currencies are recognized in other income (expense), net at each balance sheet date. We recognized a loss of $15.9 million, a loss of $7.0 million and a gain of $19.8 million for the years ended December 31, 2020, 2019 and 2018, respectively.
Derivative Instruments and Hedging Activity	Derivative Instruments and Hedging Activity We enter into derivative contracts to reduce our exposure to fluctuations in foreign currency exchange rates, interest rates and fuel prices. The criteria used to determine whether a transaction qualifies for hedge accounting treatment includes the correlation between fluctuations in the fair value of the hedged item and the fair value of the related derivative instrument and its effectiveness as a hedge. As the derivative is marked to fair value, we elected an accounting policy to net the fair value of our derivatives when a master netting arrangement exists with our counterparties. A derivative instrument that hedges a forecasted transaction or the variability of cash flows related to a recognized asset or liability may be designated as a cash flow hedge. Changes in fair value of derivative instruments that are designated as cash flow hedges are recorded as a component of accumulated other comprehensive income (loss) until the underlying hedged transactions are recognized in earnings. To the extent that an instrument is not effective as a hedge or is no longer probable of occurring, gains and losses are recognized in other income (expense), net in our consolidated statements of operations. Realized gains and losses related to our effective fuel hedges are recognized in fuel expense. For presentation in our consolidated statements of cash flows, we have elected to classify the cash flows from our cash flow hedges in the same category as the cash flows from the items being hedged.
Concentrations of Credit Risk	Concentrations of Credit Risk We monitor concentrations of credit risk associated with financial and other institutions with which we conduct significant business. Credit risk, including but not limited to counterparty non-performance under derivative instruments, our Revolving Loan Facility and new ship progress payment guarantees, is not considered significant, as we primarily conduct business with large, well-established financial institutions and insurance companies that we have well-established relationships with and that have credit risks acceptable to us or the credit risk is spread out among a large number of creditors. We do not anticipate non-performance by any of our significant counterparties.
Insurance	Insurance We use a combination of insurance and self-insurance for a number of risks including claims related to crew and guests, hull and machinery, war risk, workers’ compensation, property damage, employee healthcare and general liability. Liabilities associated with certain of these risks, including crew and passenger claims, are estimated actuarially based upon known facts, historical trends and a reasonable estimate of future expenses. While we believe these accruals are adequate, the ultimate losses incurred may differ from those recorded.
Income Taxes	Income Taxes Deferred tax assets and liabilities are calculated in accordance with the liability method. Deferred taxes are recorded using the currently enacted tax rates that apply in the periods that the differences are expected to reverse. Deferred taxes are not discounted. We provide a valuation allowance on deferred tax assets when it is more likely than not that such assets will not be realized. With respect to acquired deferred tax assets, changes within the measurement period that result from new information about facts and circumstances that existed at the acquisition date shall be recognized through a corresponding adjustment to goodwill. Subsequent to the measurement period, all other changes shall be reported as a reduction or increase to income tax expense in our consolidated statements of operations.
Share-Based Compensation	Share-Based Compensation We recognize expense for our share-based compensation awards using a fair-value-based method. Share-based compensation expense is recognized over the requisite service period for awards that are based on a service period and not contingent upon any future performance. We refer you to Note 11 – “Employee Benefits and Share-Based Compensation.”
Recently Issued Accounting Guidance	Recently Issued Accounting Guidance In August 2020, the Financial Accounting Standards Board (“FASB”) issued ASU No. 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 feature on the Private Exchangeable Notes (as defined and discussed in Note 8 – “Long-Term Debt”) which is included in additional paid-in-capital will be reclassified to long-term debt. Any related interest which has been recognized will be adjusted through retained earnings. Additional disclosures will be added as necessary. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting (“ASU 2020-04”), which provided guidance to alleviate the burden in accounting for reference rate reform by allowing certain expedients and exceptions in applying GAAP to contracts, hedging relationships and other transactions impacted by reference rate reform. The provisions apply only to those transactions that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform. Adoption of the provisions of ASU 2020-04 are optional and are effective from March 12, 2020 through December 31, 2022. We are currently evaluating the impact of ASU 2020-04 on our consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of estimated residual values of ships	​ ​ ​ ​ ​ Useful Life Ships 30 years Computer hardware and software 3 Other property and equipment 3 Leasehold improvements Shorter of lease term or asset life Ship improvements Shorter of asset life or life of the ship ​
Schedule of revenues by destination	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 ​ 2018 North America ​ $ 960,258 ​ $ 3,807,576 ​ $ 3,543,282 Europe ​ 27,602 ​ 1,666,751 ​ 1,462,698 Asia-Pacific ​ 152,976 ​ 500,842 ​ 721,404 Other ​ 139,072 ​ 487,207 ​ 327,742 Total revenue ​ $ 1,279,908 ​ $ 6,462,376 ​ $ 6,055,126 ​

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Intangible Assets Disclosure [Abstract]
Schedule of goodwill	The changes in the carrying amount of goodwill for each reporting unit for the year ended December 31, 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Reporting Unit ​ ​ ​ ​ ​ Norwegian ​ ​ ​ Regent ​ ​ ​ ​ Cruise ​ Oceania ​ Seven Seas ​ Total ​ ​ Line Cruises Cruises Goodwill Balance, December 31, 2019 $ 403,805 ​ $ 523,026 ​ $ 462,100 ​ $ 1,388,931 Impairment loss ​ (403,805) ​ (523,026) ​ (363,966) ​ (1,290,797) Balance, December 31, 2020 ​ $ — ​ $ — ​ $ 98,134 ​ $ 98,134
Schedule of gross carrying amounts included within goodwill and intangible assets, related accumulated amortization and the weighted-average amortization periods of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2020 ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ Gross Carrying ​ Accumulated ​ Net Carrying ​ Amortization ​ ​ Amount ​ Amortization ​ Amount Period (Years) Customer relationships ​ $ 120,000 ​ $ (120,000) ​ $ — 6.0 License ​ 750 ​ (406) ​ 344 10.0 Total intangible assets subject to amortization ​ $ 120,750 ​ $ (120,406) ​ $ 344 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2019 ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Average ​ ​ Gross Carrying ​ Accumulated ​ Net Carrying ​ Amortization ​ ​ Amount ​ Amortization ​ Amount Period (Years) Customer relationships ​ $ 120,000 ​ $ (110,169) ​ $ 9,831 6.0 Licenses ​ 750 ​ (331) ​ 419 10.0 Total intangible assets subject to amortization ​ $ 120,750 ​ $ (110,500) ​ $ 10,250 ​
Schedule of aggregate amortization expense for intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 ​ 2018 Amortization expense ​ $ 9,906 ​ $ 18,488 ​ $ 26,163 ​
Schedule of estimated aggregate amortization expense	​ ​ ​ ​ ​ ​ Amortization Year ended December 31, ​ Expense 2021 ​ $ 75 2022 ​ ​ 75 2023 ​ ​ 75 2024 ​ ​ 75 2025 ​ ​ 44

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Schedule of components of lease expense and revenue	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ Year Ended ​ December 31, 2020 December 31, 2019 Operating lease expense $ 19,406 $ 31,596 Variable lease expense ​ 9,705 ​ 14,284 Short-term lease expense ​ 11,076 ​ 50,832 Finance lease cost: ​ ​ ​ ​ ​ ​ Amortization of right-of-use assets ​ 1,924 ​ 1,765 Interest on lease liabilities ​ 1,072 ​ 1,239 Operating lease revenue ​ 173 ​ 446 Sublease income ​ 1,616 ​ 1,615
Schedule of lease balances	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance Sheet location December 31, 2020 December 31, 2019 Operating leases ​ ​ ​ ​ ​ ​ ​ Right-of-use assets Other long-term assets $ 209,037 $ 236,604 Current operating lease liabilities Accrued expenses and other liabilities ​ 17,700 ​ 39,126 Non-current operating lease liabilities Other long-term liabilities ​ 185,414 ​ 207,243 ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance leases ​ ​ ​ ​ ​ ​ ​ ​ Right-of-use assets Property and equipment, net ​ 11,948 ​ 13,873 Current finance lease liabilities Current portion of long-term debt ​ 5,143 ​ 6,419 Non-current finance lease liabilities Long-term debt ​ 4,648 ​ 8,812
Supplemental information related to leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Supplemental cash flow and non-cash information related to leases was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended Year Ended ​ December 31, 2020 December 31, 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ Operating cash outflows from operating leases $ 70,555 $ 75,539 Operating cash outflows from finance leases ​ 898 ​ 1,051 Financing cash outflows from finance leases ​ 4,078 ​ 2,826 ​ ​ ​ ​ ​ ​ Right-of-use assets obtained in exchange for lease obligations: ​ ​ ​ ​ ​ Operating leases ​ 823 ​ 24,834 Finance leases ​ ​ — ​ 705
Schedule of maturities of operating lease liabilities	As of December 31, 2020, maturities of lease liabilities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Finance ​ leases leases 2021 $ 27,371 ​ $ 4,891 ​ 2022 ​ ​ 32,105 ​ 3,910 ​ 2023 ​ ​ 31,866 ​ 683 ​ 2024 ​ ​ 32,065 ​ 630 ​ 2025 ​ ​ 31,827 ​ 544 ​ Thereafter ​ ​ 80,951 ​ 38 ​ Total ​ ​ 236,185 ​ ​ 10,696 ​ Less: Present value discount ​ ​ (33,071) ​ ​ (905) ​ Present value of lease liabilities $ 203,114 ​ $ 9,791 ​
Schedule of maturities of finance lease liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating ​ Finance ​ leases leases 2021 $ 27,371 ​ $ 4,891 ​ 2022 ​ ​ 32,105 ​ 3,910 ​ 2023 ​ ​ 31,866 ​ 683 ​ 2024 ​ ​ 32,065 ​ 630 ​ 2025 ​ ​ 31,827 ​ 544 ​ Thereafter ​ ​ 80,951 ​ 38 ​ Total ​ ​ 236,185 ​ ​ 10,696 ​ Less: Present value discount ​ ​ (33,071) ​ ​ (905) ​ Present value of lease liabilities $ 203,114 ​ $ 9,791 ​
Schedule of weighted average remaining lease terms and discount rates for leases	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended ​ Year Ended ​ ​ December 31, 2020 December 31, 2019 ​ Weighted average remaining lease term (years) - operating leases ​ 7.36 ​ 8.30 ​ Weighted average remaining lease term (years) - finance leases ​ 2.89 ​ ​ 3.65 ​ Weighted average discount rate - operating leases ​ ​ 3.96 % ​ 3.76 % Weighted average discount rate - finance leases ​ ​ 7.75 % ​ 7.47 %

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Schedule of accumulated other comprehensive income (loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ ​ ​ ​ Change ​ ​ Accumulated ​ Change ​ Related to ​ ​ Other ​ Related to ​ Shipboard ​ Comprehensive Cash Flow ​ Retirement ​ ​ ​ Income (Loss) ​ Hedges ​ Plan ​ Accumulated other comprehensive income (loss) at beginning of period ​ $ (297,203) ​ $ (290,009) $ (7,194) Current period other comprehensive loss before reclassifications ​ (51,704) ​ (51,642) (62) Amounts reclassified into earnings ​ 107,077 ​ 106,670 (1) 407 (2) Accumulated other comprehensive income (loss) at end of period ​ $ (241,830) ​ $ (234,981) (3) $ (6,849) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ ​ ​ ​ ​ Change ​ ​ Accumulated ​ Change ​ Related to ​ ​ Other ​ Related to ​ Shipboard ​ ​ Comprehensive ​ Cash Flow ​ Retirement ​ ​ Income (Loss) ​ Hedges ​ Plan ​ Accumulated other comprehensive income (loss) at beginning of period ​ $ (163,360) ​ $ (158,096) ​ $ (5,264) ​ Current period other comprehensive loss before reclassifications ​ (125,323) ​ (123,015) (2,308) ​ Amounts reclassified into earnings ​ (8,520) ​ (8,898) (1) 378 (2) Accumulated other comprehensive income (loss) at end of period ​ $ (297,203) ​ $ (290,009) $ (7,194) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2018 ​ ​ ​ ​ ​ Change ​ ​ Accumulated ​ Change ​ Related to ​ ​ Other ​ Related to ​ Shipboard ​ ​ Comprehensive ​ Cash Flow ​ Retirement ​ ​ Income (Loss) ​ Hedges ​ ​ Plan ​ Accumulated other comprehensive income (loss) at beginning of period ​ $ 25,253 ​ $ 33,214 $ (7,961) Current period other comprehensive income (loss) before reclassifications ​ (158,943) ​ (161,214) 2,271 Amounts reclassified into earnings ​ (29,670) ​ (30,096) (1) 426 (2) Accumulated other comprehensive income (loss) at end of period ​ $ (163,360) ​ $ (158,096) $ (5,264) (1) We refer you to Note 10 – “Fair Value Measurements and Derivatives” in these notes to consolidated financial statements for the affected line items in the consolidated statements of operations. (2) Amortization of prior-service cost and actuarial loss reclassified to other income (expense), net. (3) Includes $62.7 million of loss expected to be reclassified into earnings in the next 12 months.

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of property and equipment, net	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 2019 Ships ​ $ 14,528,133 ​ $ 14,154,578 Ships improvements ​ 2,109,015 ​ 1,865,272 Ships under construction ​ 376,062 ​ 387,749 Land and land improvements ​ 58,370 ​ 38,375 Other ​ 765,739 ​ 672,975 ​ ​ 17,837,319 ​ 17,118,949 Less: accumulated depreciation ​ (4,426,093) ​ (3,983,612) Property and equipment, net ​ $ 13,411,226 ​ $ 13,135,337

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Schedule of long-term debt	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Interest Rate ​ ​ ​ Balance ​ ​ December 31, ​ Maturities ​ December 31, ​ 2020 2019 Through 2020 2019 ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) $875.0 million senior secured Revolving Loan Facility 1.90 % — ​ 2024 ​ $ 875,000 ​ $ — $75.0 million revolving credit line ​ — ​ 2.75 % 2020 ​ ​ — ​ ​ 75,000 Term Loan A Facility 1.93 % 3.06 % 2024 ​ 1,536,417 ​ 1,565,512 $400.0 million L. Catterton exchangeable notes (1) ​ 7.00 % — ​ 2026 ​ ​ 638,185 ​ ​ — $862.5 million 6.000% exchangeable notes (2) ​ 6.00 % — ​ 2024 ​ ​ 1,444,889 ​ ​ — $450.0 million 5.375% exchangeable notes (3) ​ 5.38 % — ​ 2025 ​ ​ 608,645 ​ ​ — $675.0 million 12.25% senior secured notes (4) ​ 12.25 % — ​ 2024 ​ ​ 650,178 ​ ​ — $750.0 million 10.25% senior secured notes ​ 10.25 % — ​ 2026 ​ ​ 739,295 ​ ​ — $850.0 million 5.875% senior unsecured notes ​ 5.88 % — ​ 2026 ​ ​ 837,659 ​ ​ — $565.0 million 3.625% senior unsecured notes ​ 3.63 % 3.63 % 2024 ​ ​ 560,019 ​ ​ 558,781 $260 million Norwegian Jewel term loan 1.52 % 2.54 % 2022 ​ 221,718 ​ 221,860 $230 million Pride of America term loan ​ 1.15 % 2.81 % 2022 ​ ​ 229,558 ​ ​ 229,621 €529.8 million Breakaway one loan (5) 1.15 % 2.84 % 2025 ​ 307,529 ​ 305,969 €529.8 million Breakaway two loan (5) 3.90 % 4.10 % 2026 ​ 343,214 ​ 370,531 €590.5 million Breakaway three loan (5) 2.83 % 2.98 % 2027 ​ 481,085 ​ 478,665 €729.9 million Breakaway four loan (5) 2.85 % 2.98 % 2029 ​ 633,699 ​ 630,088 €710.8 million Seahawk 1 term loan (5) 3.69 % 3.92 % 2030 ​ 695,843 ​ 692,150 €748.7 million Seahawk 2 term loan (5) 3.71 % 3.92 % 2031 ​ 860,212 ​ 856,188 Leonardo newbuild one loan 2.68 % 2.68 % 2034 ​ 95,563 ​ 48,009 Leonardo newbuild two loan 2.77 % 2.77 % 2035 ​ 48,009 ​ 48,009 Leonardo newbuild three loan 1.22 % 1.22 % 2036 ​ 46,519 ​ 42,700 Leonardo newbuild four loan 1.31 % 1.31 % 2037 ​ 46,519 ​ 42,700 Splendor newbuild loan 2.97 % — ​ 2032 ​ 402,177 ​ — Explorer newbuild loan 3.39 % 3.43 % 2028 ​ 251,634 ​ 242,449 Marina newbuild loan 1.03 % 2.75 % 2025 ​ 134,821 ​ 156,319 Riviera newbuild loan 0.96 % 2.48 % 2024 ​ 203,038 ​ 202,233 Term loan - newbuild related ​ 2.50 % — ​ 2021 ​ ​ 26,387 ​ ​ — Finance lease and license obligations Various ​ Various ​ 2028 ​ 27,547 ​ 34,909 Total debt ​ 12,945,359 ​ 6,801,693 Less: current portion of long-term debt ​ (124,885) ​ (746,358) Total long-term debt ​ $ 12,820,474 ​ $ 6,055,335 (1) Includes a conversion option of $623.2 million and related debt discount of $399.4 million as of December 31, 2020. (2) Includes a conversion option of $921.0 million and related debt discount of $309.8 million as of December 31, 2020. (3) Includes a conversion option of $311.9 million and related debt discount of $142.4 million as of December 31, 2020. (4) Includes original issue discount of $5.9 million as of December 31, 2020. (5) Currently U.S. dollar-denominated. ​
Schedule of debt instrument interest rate	​ ​ ​ ​ ​ ​ ​ Margin ​ €529.8 million Breakaway one loan (Norwegian Breakaway) ​ 0.90 % €529.8 million Breakaway two loan (Norwegian Getaway) ​ 1.20 % €590.5 million Breakaway three loan (Norwegian Escape) ​ 1.50 % €729.9 million Breakaway four loan (Norwegian Joy) ​ 1.50 % €710.8 million Seahawk 1 term loan (Norwegian Bliss) ​ 1.00 % €748.7 million Seahawk 2 term loan (Norwegian Encore) ​ 1.00 % ​ ​ ​ ​ ​ ​ ​ Margin ​ €529.8 million Breakaway one loan (Norwegian Breakaway) ​ 1.10 % €529.8 million Breakaway two loan (Norwegian Getaway) ​ 1.40 % €590.5 million Breakaway three loan (Norwegian Escape) ​ 1.50 % €729.9 million Breakaway four loan (Norwegian Joy) ​ 1.50 % €710.8 million Seahawk 1 term loan (Norwegian Bliss) ​ 1.20 % €748.7 million Seahawk 2 term loan (Norwegian Encore) ​ 1.20 % Explorer newbuild loan ​ 3.00 % Splendor newbuild loan ​ 1.95 % Marina newbuild loan ​ 0.75 % Riviera newbuild loan ​ 0.75 %
Schedule of deferred loans	​ ​ ​ ​ ​ ​ ​ Margin ​ Explorer newbuild loan ​ 2.80 % Splendor newbuild loan ​ 1.75 % Marina newbuild loan ​ 0.55 % Riviera newbuild loan ​ 0.55 %
Schedule of liability components of exchangeable notes	The net carrying amounts of the liability components of our exchangeable notes consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ December 31, ​ 2020 Principal amount ​ $ 1,726,811 Less: Unamortized debt discount, including deferred financing fees ​ ​ (891,236) Net carrying value ​ $ 835,575
Schedule of interest expense related to exchangeable notes	The following table presents the interest expense recognized related to the exchangeable notes (in thousands): ​ ​ ​ ​ ​ ​ Year Ended ​ ​ December 31, 2020 Interest expense, including amortization of debt discounts and coupon interest ​ $ 130,949
Schedule of principal repayments on long-term debt including finance lease obligations	The following are scheduled principal repayments on long-term debt, including finance lease obligations, as of December 31, 2020 for each of the next five years (in thousands): ​ ​ ​ ​ ​ Year Amount 2021 ​ $ 124,829 2022 ​ 1,192,923 2023 ​ 917,893 2024 ​ 5,051,867 2025 ​ 1,045,773 Thereafter ​ 3,818,798 Total ​ $ 12,152,083

Fair Value Measurements and D_2

Fair Value Measurements and Derivatives (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of derivatives measured at fair value and disclosed by balance sheet location	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets ​ Liabilities ​ ​ ​ ​ ​ December 31, ​ December 31, ​ December 31, ​ December 31, ​ ​ Balance Sheet Location 2020 2019 2020 2019 ​ Derivative Contracts Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ ​ ​ ​ Other long-term assets ​ $ — ​ $ 277 ​ $ — ​ $ — ​ ​ Accrued expenses and other liabilities ​ — ​ 2,300 ​ 35,973 ​ 18,257 ​ ​ Other long-term liabilities ​ — ​ 683 ​ 28,947 ​ 17,763 ​ Foreign currency contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Prepaid expenses and other assets ​ 5,779 ​ — ​ — ​ — ​ ​ Other long-term assets ​ 43,250 ​ — ​ — ​ — ​ ​ Accrued expenses and other liabilities ​ — ​ — ​ 14,778 ​ 33,475 ​ ​ Other long-term liabilities ​ 6,821 ​ 169 ​ 44,938 ​ 118,500 ​ Interest rate contracts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Accrued expenses and other liabilities ​ — ​ — ​ 6,776 ​ 2,178 ​ ​ ​ Other long-term liabilities ​ ​ — ​ ​ — ​ ​ 452 ​ ​ 1,861 ​ Total derivatives designated as hedging instruments ​ ​ ​ $ 55,850 ​ $ 3,429 ​ $ 131,864 ​ $ 192,034 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Derivative Contracts Not Designated as Hedging Instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ Accrued expenses and other liabilities ​ $ 546 ​ $ — ​ $ 6,732 ​ $ — ​ ​ ​ Other long-term liabilities ​ ​ — ​ ​ — ​ ​ 3,534 ​ ​ — ​ Debt conversion options Exchangeable notes ​ ​ — ​ ​ — ​ ​ 1,856,145 ​ ​ — ​ Total derivatives not designated as hedging instruments ​ ​ ​ $ 546 ​ $ — ​ $ 1,866,411 ​ $ — ​ Total derivatives ​ ​ ​ $ 56,396 ​ $ 3,429 ​ $ 1,998,275 ​ $ 192,034 ​ ​
Schedule of gross and net amounts recognized within assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Gross ​ ​ ​ ​ Gross ​ Amounts ​ Total Net ​ Amounts ​ ​ ​ December 31, 2020 ​ Amounts ​ Offset ​ Amounts ​ Not Offset ​ Net Amounts Assets ​ $ 49,029 ​ $ — ​ $ 49,029 ​ $ (49,029) ​ $ — Liabilities ​ ​ 1,998,275 ​ ​ (7,367) ​ ​ 1,990,908 ​ ​ (1,913,496) ​ ​ 77,412 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ ​ Gross ​ ​ ​ ​ Gross ​ Amounts ​ Total Net ​ Amounts ​ ​ ​ December 31, 2019 ​ Amounts ​ Offset ​ Amounts ​ Not Offset ​ Net Amounts Assets ​ $ 277 ​ $ — ​ $ 277 ​ $ — ​ $ 277 Liabilities ​ ​ 192,034 ​ ​ (3,152) ​ ​ 188,882 ​ ​ (149,863) ​ ​ 39,019 ​
Schedule of cash flow hedges included in accumulated other comprehensive income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Location of Gain ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (Loss) Reclassified ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ from Accumulated ​ Amount of Gain (Loss) Reclassified ​ Amount of Gain (Loss) ​ Other Comprehensive ​ from Accumulated Other ​ Recognized in Other ​ Income (Loss) into ​ Comprehensive Derivatives Comprehensive Income ​ Income ​ Income (Loss) into Income ​ Year Ended December 31, ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 ​ 2020 2019 2018 Fuel contracts $ (157,669) ​ $ 46,154 ​ $ (52,949) ​ Fuel ​ $ (45,488) ​ $ 14,093 ​ $ 34,410 Fuel contracts ​ — ​ ​ — ​ ​ — ​ Other income (expense), net ​ ​ (49,653) ​ — ​ — Foreign currency contracts 116,496 ​ (163,197) ​ (108,911) ​ Depreciation and amortization ​ (4,929) ​ (3,062) ​ (3,463) Interest rate contracts (10,469) ​ (5,972) ​ 646 ​ Interest expense, net ​ (6,600) ​ (2,133) ​ (851) Total gain (loss) recognized in other comprehensive income $ (51,642) ​ $ (123,015) ​ $ (161,214) ​ ​ $ (106,670) ​ $ 8,898 ​ $ 30,096
Schedule of effects of derivatives designated as cash flow hedges	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2020 ​ ​ ​ ​ Depreciation ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ and ​ Interest ​ Other Income ​ ​ Fuel Amortization Expense, net (Expense), net Total amounts of income and expense line items presented in the consolidated statements of operations in which the effects of cash flow hedges are recorded ​ $ 264,712 ​ $ 717,840 ​ $ 520,063 ​ ​ (984,501) ​ ​ ​ ​ ​ ​ ​ Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into income ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ (45,488) ​ ​ — ​ ​ — ​ ​ — Foreign currency contracts ​ ​ — ​ ​ (4,929) ​ ​ — ​ ​ — Interest rate contracts ​ ​ — ​ ​ — ​ ​ (6,600) ​ ​ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of loss reclassified from accumulated other comprehensive income (loss) into income as a result that a forecasted transaction is no longer probable of occurring ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ — ​ ​ — ​ ​ — ​ ​ (49,653) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of gain recognized in income as a result of failing effectiveness tests ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ — ​ ​ — ​ ​ — ​ ​ 5,507 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2019 ​ Year Ended December 31, 2018 ​ ​ ​ ​ ​ Depreciation ​ ​ ​ ​ ​ ​ Depreciation ​ ​ ​ ​ ​ ​ ​ and ​ Interest ​ ​ ​ ​ and ​ Interest ​ Fuel Amortization Expense, net Fuel Amortization Expense, net Total amounts of income and expense line items presented in the consolidated statements of operations in which the effects of cash flow hedges are recorded ​ $ 409,602 ​ $ 646,188 ​ $ 272,867 ​ $ 392,685 ​ $ 561,060 ​ $ 270,404 ​ ​ ​ ​ ​ ​ ​ Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) into income ​ ​ ​ ​ ​ ​ Fuel contracts ​ ​ 14,093 ​ ​ — ​ ​ — ​ ​ 34,410 ​ ​ — ​ ​ — Foreign currency contracts ​ ​ — ​ ​ (3,062) ​ ​ — ​ ​ — ​ ​ (3,463) ​ ​ — Interest rate contracts ​ ​ — ​ ​ — ​ ​ (2,133) ​ ​ — ​ ​ — ​ ​ (851)
Schedule of effects of derivatives not designated as cash flow hedges	The effects of derivatives not designated as hedging instruments on the consolidated statements of operations include the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amount of Gain (Loss) Recognized in Income ​ ​ ​ Year Ended December 31, ​ Location of Gain (Loss) 2020 2019 2018 Derivatives not designated as hedging instruments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fuel contracts Other income (expense), net ​ $ 20,932 ​ $ — ​ $ — Debt conversion options Other income (expense), net ​ ​ (938,614) ​ ​ — ​ ​ —

Employee Benefits and Share-B_2

Employee Benefits and Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of summary of option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Number of Share Option Awards ​ Weighted-Average Exercise Price ​ Average ​ Aggregate ​ Time- Performance- Market- Time- Performance- Market- Contractual Intrinsic ​ ​ Based ​ Based ​ Based ​ Based ​ Based ​ Based ​ Term ​ Value ​ ​ Awards ​ Awards ​ Awards ​ Awards ​ Awards ​ Awards ​ (years) ​ (in thousands) Outstanding as of January 1, 2020 4,918,554 115,489 208,333 ​ $ 51.84 ​ $ 59.11 ​ $ 59.43 5.42 ​ $ 33,413 Exercised (48,221) ​ (906) — ​ ​ 44.38 ​ ​ 19.00 ​ ​ — ​ Forfeited and cancelled (345,126) ​ — — ​ ​ 51.24 ​ ​ — ​ ​ — ​ Outstanding as of December 31, 2020 4,525,207 114,583 208,333 ​ $ 51.96 ​ $ 59.43 ​ $ 59.43 4.42 ​ $ — Vested and expected to vest as of December 31, 2020 4,525,207 114,583 — ​ $ 51.96 ​ $ 59.43 ​ $ — 4.42 ​ $ — Exercisable as of December 31, 2020 4,525,207 114,583 — ​ $ 51.96 ​ $ 59.43 ​ $ — 4.42 ​ $ —
Schedule of summary of restricted share unit activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Weighted- Number of Weighted- Number of Weighted- ​ ​ Time-Based ​ Average Grant ​ Performance- ​ Average Grant ​ Market- ​ Average Grant ​ ​ Awards ​ Date Fair Value ​ Based Awards ​ Date Fair Value ​ Based Awards ​ Date Fair Value Non-vested as of January 1, 2020 ​ 3,245,625 ​ $ 54.94 ​ 1,129,396 ​ $ 56.09 ​ 50,000 ​ $ 59.43 Granted 5,380,123 ​ ​ 23.69 945,598 (1) ​ 27.75 — ​ ​ — Vested (1,610,315) ​ ​ 54.01 (192,523) ​ ​ 56.27 — ​ ​ — Forfeited or expired (351,508) ​ ​ 43.53 (317,287) ​ ​ 53.72 — ​ ​ — Non-vested as of December 31, 2020 6,663,925 ​ $ 30.54 1,565,184 ​ $ 39.42 50,000 ​ $ 59.43 Non-vested and expected to vest as of December 31, 2020 ​ 6,663,925 ​ $ 30.54 981,098 ​ $ 41.71 — ​ $ — (1) Number of performance-based RSU awards included assumes maximum achievement of performance targets.
Schedule of compensation expense recognized for share-based compensation	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, Classification of expense 2020 2019 2018 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Payroll and related (1) ​ $ 21,190 ​ $ 17,597 ​ $ 15,629 Marketing, general and administrative (2) ​ 90,107 ​ 77,458 ​ 100,354 Total share-based compensation expense ​ $ 111,297 ​ $ 95,055 ​ $ 115,983
Schedule of amounts related to the Shipboard Retirement Plan	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of or for the Year Ended December 31, ​ 2020 2019 2018 Pension expense: ​ ​ ​ Service cost ​ $ 2,665 ​ $ 2,135 ​ $ 2,167 Interest cost ​ 895 ​ 1,001 ​ 857 Amortization of prior service cost ​ 378 ​ 378 ​ 378 Amortization of actuarial loss ​ 29 ​ — ​ 51 Total pension expense ​ $ 3,967 ​ $ 3,514 ​ $ 3,453 Change in projected benefit obligation: ​ ​ ​ Projected benefit obligation at beginning of year ​ $ 28,695 ​ $ 24,318 ​ $ 24,587 Service cost ​ 2,665 ​ 2,135 ​ 2,167 Interest cost ​ 895 ​ 1,001 ​ 857 Actuarial (gain) loss ​ 62 ​ 2,308 ​ (2,271) Direct benefit payments ​ (698) ​ (1,067) ​ (1,022) Projected benefit obligation at end of year ​ $ 31,619 ​ $ 28,695 ​ $ 24,318 Amounts recognized in the consolidated balance sheets: ​ ​ ​ Projected benefit obligation ​ $ 31,619 ​ $ 28,695 ​ $ 24,318 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the Year Ended December 31, ​ 2020 2019 2018 Amounts recognized in accumulated other comprehensive income (loss): ​ ​ ​ Prior service cost ​ $ (3,403) ​ $ (3,781) ​ $ (4,159) Accumulated actuarial loss ​ (3,446) ​ (3,413) ​ (1,105) Accumulated other comprehensive income (loss) ​ $ (6,849) ​ $ (7,194) ​ $ (5,264)
Schedule of pension benefits expected to be paid in each of the next five years and in aggregate for the five years thereafter	​ ​ ​ ​ Year Amount 2021 ​ $ 918 2022 ​ ​ 989 2023 ​ ​ 1,118 2024 ​ ​ 1,224 2025 ​ ​ 1,339 Next five years ​ ​ 11,004
Performance-Based Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule of assumptions used within the option-pricing model	​ ​ ​ ​ 2018 Dividend yield —% Expected share price volatility 31.50% - 32.20% Risk-free interest rate 2.48% - 2.58% Expected term 3.72 - 4.22 years ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of components of net income before income taxes	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Bermuda ​ $ — ​ $ — ​ $ — Foreign - Other ​ (4,986,613) ​ ​ 914,001 ​ ​ 974,172 Net income (loss) before income taxes ​ $ (4,986,613) ​ $ 914,001 ​ $ 974,172 ​
Schedule of components of the provision for income taxes	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Current: ​ ​ ​ Bermuda ​ $ — ​ $ — ​ $ — United States ​ (326) ​ 837 ​ (836) Foreign - Other ​ (5,502) ​ (6,294) ​ (5,371) Total current: ​ (5,828) ​ (5,457) ​ (6,207) Deferred: ​ ​ ​ Bermuda ​ — ​ — ​ — United States ​ (15,613) ​ 32,315 ​ (2,001) Foreign - Other ​ (129) ​ 347 ​ 226 Total deferred: ​ (15,742) ​ 32,662 ​ (1,775) Income tax benefit (expense) ​ $ (21,570) ​ $ 27,205 ​ $ (7,982) ​
Schedule of reconciliation of income tax benefit (expense)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, ​ 2020 2019 2018 Tax at Bermuda statutory rate ​ $ — ​ $ — ​ $ — Foreign income taxes at different rates ​ 17,051 ​ (9,819) ​ (11,119) Tax contingencies ​ (626) ​ (206) ​ (6) Return to provision adjustments ​ 9 ​ 1,538 ​ 3,055 Benefit (expense) from change in tax rate ​ — ​ (7) ​ 88 Valuation allowance ​ (38,004) ​ 35,699 ​ — Income tax benefit (expense) ​ $ (21,570) ​ $ 27,205 ​ $ (7,982) ​
Schedule of deferred tax assets and liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2020 2019 Deferred tax assets: ​ ​ ​ Loss carryforwards ​ $ 77,093 ​ $ 54,122 Other ​ 4,561 ​ 2,356 Valuation allowance ​ (42,876) ​ (5,847) Total net deferred assets ​ 38,778 ​ 50,631 Deferred tax liabilities: ​ ​ Property and equipment ​ (36,463) ​ (34,724) Total deferred tax liabilities ​ (36,463) ​ (34,724) Net deferred tax asset (liability) ​ $ 2,315 ​ $ 15,907 ​
Schedule of reconciliation of the total amounts of unrecognized tax benefits	​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ 2020 2019 Unrecognized tax benefits, beginning of the year ​ $ 732 ​ $ 532 Gross increases in tax positions from prior periods ​ 620 ​ 200 Unrecognized tax benefits, end of year ​ $ 1,352 ​ $ 732 ​

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Ship Construction Contracts
Schedule of other commitments	​ ​ ​ ​ ​ Year Amount 2021 ​ $ 463,549 2022 ​ 1,118,430 2023 ​ 2,168,127 2024 ​ 1,092,766 2025 ​ 1,758,314 Thereafter ​ 1,870,807 Total minimum annual payments ​ $ 8,471,993 ​
Port Facility Commitments
Schedule of other commitments	​ ​ ​ ​ ​ Year Amount 2021 ​ $ 71,691 2022 ​ 71,296 2023 ​ 71,460 2024 ​ 75,822 2025 ​ 70,132 Thereafter ​ 1,707,376 Total port facility future commitments ​ $ 2,067,777

Quarterly Selected Financial _2

Quarterly Selected Financial Data (Unaudited) (in thousands) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ First Quarter ​ Second Quarter ​ Third Quarter ​ Fourth Quarter ​ 2020 2019 2020 2019 2020 2019 2020 2019 Total revenue ​ $ 1,246,882 ​ $ 1,403,630 ​ $ 16,929 ​ $ 1,664,277 ​ $ 6,518 ​ $ 1,913,851 ​ $ 9,579 ​ $ 1,480,618 Operating income (loss) ​ $ (1,823,279) ​ $ 158,904 ​ $ (594,537) ​ $ 309,594 ​ $ (517,478) ​ $ 512,337 ​ $ (546,755) ​ $ 199,878 Net income (loss) ​ $ (1,882,266) ​ $ 119,404 ​ $ (951,065) ​ $ 243,276 ​ $ (758,152) ​ $ 455,309 ​ $ (1,416,700) ​ $ 123,217

Description of Busines (Details

Description of Busines (Details)	Dec. 31, 2020item
Description Of Business And Organization [Line Items]
Number of cruise ships	28
Capacity of ship, berths	59,150
Number of additional ships	9
Ship to be delivered in 2023
Description Of Business And Organization [Line Items]
Number of additional ships	1
Ships launching period in 2023 through 2025
Description Of Business And Organization [Line Items]
Number of additional ships	2
Ships launching period in 2027
Description Of Business And Organization [Line Items]
Number of additional ships	9
Increased number of berths	83,000
Ships launching period in 2027 | Project Leonardo
Description Of Business And Organization [Line Items]
Number of additional ships	6

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Liquidity and Management's Plan (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2020USD ($)	Dec. 31, 2020USD ($)item	Apr. 30, 2022USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Oct. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Number of reporting units | item		3
Cash and cash equivalents		$ 3,299,340			$ 231,239		$ 162,419	$ 170,757
Substantial Doubt about Going Concern, within One Year [true false]		false
Subsequent Event
Debt Instrument [Line Items]
Additional liquidity to meet ongoing obligations			$ 560,000
$875 Million Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Revolving credit line amount		$ 875,000			$ 875,000
$675 million senior secured revolving credit facility
Debt Instrument [Line Items]
Amount outstanding				$ 675,000
Revolving credit line amount				675,000		$ 675,000
Repayment of Epic credit facility	$ 675,000
Fourth Amended and Restated Credit Agreement | Revolving Loan Facility | $875 Million Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Amount outstanding				$ 875,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Estimated Useful Lives of Assets (Details)	12 Months Ended
	Dec. 31, 2020
Ships
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	30 years
Computer hardware and software | Minimum
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Computer hardware and software | Maximum
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	10 years
Other property and equipment | Minimum
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Other property and equipment | Maximum
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	40 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	Shorter of lease term or asset life
Ship Improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, useful life	Shorter of asset life or life of the ship

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Revenues by Destination (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Significant Accounting Policies [Line Items]
Total revenue	$ 9,579	$ 6,518	$ 16,929	$ 1,246,882	$ 1,480,618	$ 1,913,851	$ 1,664,277	$ 1,403,630	$ 1,279,908	$ 6,462,376	$ 6,055,126
North America
Schedule Of Significant Accounting Policies [Line Items]
Total revenue									960,258	3,807,576	3,543,282
Europe
Schedule Of Significant Accounting Policies [Line Items]
Total revenue									27,602	1,666,751	1,462,698
Asia-Pacific
Schedule Of Significant Accounting Policies [Line Items]
Total revenue									152,976	500,842	721,404
Other
Schedule Of Significant Accounting Policies [Line Items]
Total revenue									$ 139,072	$ 487,207	$ 327,742

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2020USD ($)item	Dec. 31, 2020USD ($)itemsegment	Dec. 31, 2019USD ($)item	Dec. 31, 2018USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Allowance for credit losses	$ 35,400	$ 35,400	$ 10,600
Advertising costs included in prepaid expenses and other assets	$ 900	900	5,900
Expenses related to advertising costs		$ 216,500	400,600	$ 327,300
Reduction in estimated residual values, percentage	15.00%	15.00%
Number of reporting units | item		3
Impairment of goodwill		$ 1,290,797
Goodwill	$ 98,134	98,134	1,388,931
Trade names	$ 500,525	$ 500,525	817,525
Number of reportable segments | segment		1
Number of cruise ships | item	28	28
Ship, carrying value	$ 13,411,226	$ 13,411,226	13,135,337
Paid-in-kind interest	19,300	19,349
Foreign currency transaction (gains) loss		15,900	7,000	$ 19,800
Trade names
Schedule Of Significant Accounting Policies [Line Items]
Impairment of trade names		0
Trade names	500,500	500,500
Regent
Schedule Of Significant Accounting Policies [Line Items]
Goodwill	$ 98,100	98,100
Regent Seven Seas And Oceania Cruises | Trade names
Schedule Of Significant Accounting Policies [Line Items]
Impairment of trade names		$ 317,000
Bahamas registry | Ships
Schedule Of Significant Accounting Policies [Line Items]
Number of cruise ships | item	19	19
Ship, carrying value	$ 9,900,000	$ 9,900,000	$ 10,200,000
Marshall Island registry | Ships
Schedule Of Significant Accounting Policies [Line Items]
Number of cruise ships | item	8	8	7
Ship, carrying value	$ 2,400,000	$ 2,400,000	$ 1,900,000
U.S | Ships
Schedule Of Significant Accounting Policies [Line Items]
Number of cruise ships | item	1	1	1
Ship, carrying value	$ 300,000	$ 300,000	$ 300,000
Revenue
Schedule Of Significant Accounting Policies [Line Items]
Concentration risk, benchmark		No other individual country’s revenues exceeded 10% in any of our last three years.	No other individual country’s revenues exceeded 10% in any of our last three years.	No other individual country’s revenues exceeded 10% in any of our last three years.
Revenue | U.S | Passenger ticket
Schedule Of Significant Accounting Policies [Line Items]
Percentage of revenue attributable to U.S.- sourced passengers		83.00%	81.00%	77.00%

Revenue and Expense from Cont_2

Revenue and Expense from Contracts with Customers (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)itemsegment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Capacity of ship, berths | item	59,150
Period for final payment prior to embarkation	60 days
Number of days prior to departure the cruises booked can be cancelled	15 days
Receivables from customers included in accounts receivable, net	$ 1	$ 15.3
Number of reportable segments | segment	1
Contract costs incurred to obtain customers	$ 41.3	143.5
Contract costs to fulfill contracts with customers	5.5	49.7
Advanced ticket sales	23.1	1,400
Revenue recognized included in contract liabilty	900	$ 1,200	$ 1,000
Cost to obtain the contract	$ 171.5

Revenue and Expense from Cont_3

Revenue and Expense from Contracts with Customers - Remaining Performance Obligation (Details)	Dec. 31, 2020
Minimum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-05-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	120 days
Maximum | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	180 days

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Goodwill [Roll Forward]
Balance, December 31, 2019	$ 1,388,931
Impairment loss	(1,290,797)
Balance, March 31, 2020	98,134
Norwegian Cruise Line
Goodwill [Roll Forward]
Balance, December 31, 2019	403,805
Impairment loss	(403,805)
Oceania Cruises
Goodwill [Roll Forward]
Balance, December 31, 2019	523,026
Impairment loss	(523,026)
Regent Seven Seas Cruises
Goodwill [Roll Forward]
Balance, December 31, 2019	462,100
Impairment loss	(363,966)
Balance, March 31, 2020	$ 98,134

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Gross Carrying Amount	$ 120,750	$ 120,750
Intangible assets subject to amortization, Accumulated Amortization	(120,406)	(110,500)
Intangible assets subject to amortization, Net Carrying Amount	344	10,250
Customer relationship
Finite-Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Gross Carrying Amount	120,000	120,000
Intangible assets subject to amortization, Accumulated Amortization	$ (120,000)	(110,169)
Intangible assets subject to amortization, Net Carrying Amount		$ 9,831
Weighted-Average Amortization Period (Years)	6 years	6 years
Licenses
Finite-Lived Intangible Assets [Line Items]
Intangible assets subject to amortization, Gross Carrying Amount	$ 750	$ 750
Intangible assets subject to amortization, Accumulated Amortization	(406)	(331)
Intangible assets subject to amortization, Net Carrying Amount	$ 344	$ 419
Weighted-Average Amortization Period (Years)	10 years	10 years

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets Disclosure [Abstract]
Amortization expense	$ 9,906	$ 18,488	$ 26,163

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Future Estimated Amortization Expense (Details) $ in Thousands	Dec. 31, 2020USD ($)
Amortization Expense
2021	$ 75
2022	75
2023	75
2024	75
2025	$ 44

Goodwill and Intangible Asset_6

Goodwill and Intangible Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)item	Dec. 31, 2019USD ($)
Schedule Of Intangible Assets [Line Items]
Number of reporting units | item	3
Goodwill	$ 98,134	$ 1,388,931
Trade names
Schedule Of Intangible Assets [Line Items]
Impairment of trade names	0
Norwegian Cruise Line
Schedule Of Intangible Assets [Line Items]
Goodwill		403,805
Oceania Cruises
Schedule Of Intangible Assets [Line Items]
Goodwill		523,026
Oceania Cruises | Trade names
Schedule Of Intangible Assets [Line Items]
Impairment of trade names	170,000
Regent Seven Seas Cruises
Schedule Of Intangible Assets [Line Items]
Goodwill	98,134	$ 462,100
Regent Seven Seas Cruises | Trade names
Schedule Of Intangible Assets [Line Items]
Impairment of trade names	147,000
Trade names
Schedule Of Intangible Assets [Line Items]
Carrying values	500,500
Trade names | Norwegian Cruise Line
Schedule Of Intangible Assets [Line Items]
Carrying values	207,500
Trade names | Oceania Cruises
Schedule Of Intangible Assets [Line Items]
Carrying values	140,000
Trade names | Regent Seven Seas Cruises
Schedule Of Intangible Assets [Line Items]
Carrying values	$ 153,000

Leases - Components of Lease Ex

Leases - Components of Lease Expense and Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease expense	$ 19,406	$ 31,596
Variable lease expense	9,705	14,284
Short-term lease expense	11,076	50,832
Finance lease cost:
Amortization of right-to-use assets	1,924	1,765
Interest on lease liabilities	1,072	1,239
Operating lease revenue	173	446
Sublease income	$ 1,616	$ 1,615

Leases - Lease Balances (Detail

Leases - Lease Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other long-term assets
Operating leases
Right-of-use assets	$ 209,037	$ 236,604
Accrued expenses and other liabilities
Operating leases
Current operating lease liabilities	17,700	39,126
Other long-term liabilities
Operating leases
Non-current operating lease liabilities	185,414	207,243
Property and equipment, net
Finance leases
Right-of-use assets	11,948	13,873
Current portion of long-term debt
Finance leases
Current finance lease liabilities	5,143	6,419
Long-term debt
Finance leases
Non-current finance lease liabilities	$ 4,648	$ 8,812

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow and Non-Cash Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows from operating leases	$ 70,555	$ 75,539
Operating cash outflows from finance leases	898	1,051
Financing cash outflows from finance leases	4,078	2,826
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$ 823	24,834
Finance leases		$ 705

Leases - Other Supplemental Inf

Leases - Other Supplemental Information (Details)	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Weighted average remaining lease term (years) - operating leases	7 years 4 months 9 days	8 years 3 months 18 days
Weighted average remaining lease term (years) - finance leases	2 years 10 months 20 days	3 years 7 months 24 days
Weighted average discount rate - operating leases	3.96%	3.76%
Weighted average discount rate - finance leases	7.75%	7.47%

Leases - Maturities of Lease Li

Leases - Maturities of Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Operating leases
2021	$ 27,371
2022	32,105
2023	31,866
2024	32,065
2025	31,827
Thereafter	80,951
Total	236,185
Less: Present value discount	(33,071)
Present value of lease liabilities	203,114
Finance leases
2021	4,891
2022	3,910
2023	683
2024	630
2025	544
Thereafter	38
Total	10,696
Less: Present value discount	(905)
Present value of lease liabilities	$ 9,791

Leases (Details)

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Liability, Statement of Financial Position [Extensible List]	nclc:AccruedLiabilitiesAndOtherLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent		nclc:AccruedLiabilitiesAndOtherLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent
Operating lease liability	$ 203,114
Lessee, Operating Lease, Existence of Option to Extend [true false]	true
Renewal term	5 years
Downward adjustment on leased assets	$ 17,700
Reclassification of liability	2,100
Undiscounted minimum annual guarantees	$ 1,200,000
Expense under non-cancelable operating leases		$ 16,900

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of period	$ (297,203)	$ (163,360)	$ 25,253
Current period other comprehensive income (loss) before reclassifications	(51,704)	(125,323)	(158,943)
Amounts reclassified into earnings	107,077	(8,520)	(29,670)
Accumulated other comprehensive income (loss) at end of period	(241,830)	(297,203)	(163,360)
Amount of loss expected to be reclassified into earnings	(62,700)
Change Related to Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of period	(290,009)	(158,096)	33,214
Current period other comprehensive income (loss) before reclassifications	(51,642)	(123,015)	(161,214)
Amounts reclassified into earnings	106,670	(8,898)	(30,096)
Accumulated other comprehensive income (loss) at end of period	(234,981)	(290,009)	(158,096)
Change Related to Shipboard Retirement Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) at beginning of period	(7,194)	(5,264)	(7,961)
Current period other comprehensive income (loss) before reclassifications	(62)	(2,308)	2,271
Amounts reclassified into earnings	407	378	426
Accumulated other comprehensive income (loss) at end of period	$ (6,849)	$ (7,194)	$ (5,264)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) (Parentheticals) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Statement Of Income And Comprehensive Income [Abstract]
Gain (loss) expected to be reclassified into earnings in next 12 months	$ (62.7)

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 17,837,319	$ 17,118,949
Less: accumulated depreciation	(4,426,093)	(3,983,612)
Property and equipment, net	13,411,226	13,135,337
Ships
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	14,528,133	14,154,578
Ships improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	2,109,015	1,865,272
Ships under construction
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	376,062	387,749
Land and land improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	58,370	38,375
Other property and equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, gross	$ 765,739	$ 672,975

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 707.9	$ 627.7	$ 534.9
Repairs and maintenance expenses including Dry-docking expenses	129.9	199.7	199.5
Interest costs associated with construction of ship	25.2	$ 32.9	$ 30.4
Ships improvements
Property, Plant and Equipment [Line Items]
Costs associated with ship improvements	$ 341.5

Long-Term Debt - Summary of Lon

Long-Term Debt - Summary of Long-Term Debt (Details) $ in Thousands, € in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)	Jul. 31, 2020	May 31, 2020USD ($)	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Extended maturity year	2028
Finance lease and license obligations	$ 27,547				$ 34,909
Long-term debt	835,575
Total debt	12,945,359				6,801,693
Less: current portion of long-term debt	(124,885)				(746,358)
Total long-term debt	$ 12,820,474				$ 6,055,335
$875 Million Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Interest Rate	1.90%	1.90%
Extended maturity year	2024
Long-term debt	$ 875,000
$75.0 Million Revolving Credit Line
Debt Instrument [Line Items]
Interest Rate					2.75%
Extended maturity year	2020
Long-term debt					$ 75,000
New Term Loan A Facility
Debt Instrument [Line Items]
Interest Rate	1.93%	1.93%			3.06%
Extended maturity year	2024
Long-term debt	$ 1,536,417				$ 1,565,512
$400.0 million L. Catterton exchangeable notes
Debt Instrument [Line Items]
Interest Rate	7.00%	7.00%
Extended maturity year	2026
Long-term debt	$ 638,185
$862.5 million 6.000% exchangeable notes
Debt Instrument [Line Items]
Interest Rate	6.00%	6.00%		6.00%
Extended maturity year	2024
Long-term debt	$ 1,444,889
$450.0 million 5.375% exchangeable notes
Debt Instrument [Line Items]
Interest Rate	5.38%	5.38%	5.375%
Extended maturity year	2025
Long-term debt	$ 608,645
$675.0 million 12.25% senior secured notes
Debt Instrument [Line Items]
Interest Rate	12.25%	12.25%		12.25%
Extended maturity year	2024
Long-term debt	$ 650,178			$ 675,000
$750.0 million 10.25% senior secured notes
Debt Instrument [Line Items]
Interest Rate	10.25%	10.25%	10.25%
Extended maturity year	2026
Long-term debt	$ 739,295
Unsecured Notes
Debt Instrument [Line Items]
Interest Rate	5.88%	5.88%
Extended maturity year	2026
Long-term debt	$ 837,659
$565.0 Million 3.625% Senior Unsecured Notes
Debt Instrument [Line Items]
Interest Rate	3.63%	3.63%			3.63%
Extended maturity year	2024
Long-term debt	$ 560,019				$ 558,781
$260 Million Norwegian Jewel Term Loan
Debt Instrument [Line Items]
Interest Rate	1.52%	1.52%			2.54%
Extended maturity year	2022
Long-term debt	$ 221,718				$ 221,860
$230 Million Pride of America Term Loan
Debt Instrument [Line Items]
Interest Rate	1.15%	1.15%			2.81%
Extended maturity year	2022
Long-term debt	$ 229,558				$ 229,621
EUR 529.8 million Breakaway one loan
Debt Instrument [Line Items]
Interest Rate	1.15%	1.15%			2.84%
Extended maturity year	2025
Long-term debt	$ 307,529				$ 305,969
EUR 529.8 million Breakaway two loan
Debt Instrument [Line Items]
Interest Rate	3.90%	3.90%			4.10%
Extended maturity year	2026
Long-term debt	$ 343,214				$ 370,531
EUR 590.5 million Breakaway three loan
Debt Instrument [Line Items]
Interest Rate	2.83%	2.83%			2.98%
Extended maturity year	2027
Long-term debt	$ 481,085				$ 478,665
EUR 729.9 million Breakaway four loan
Debt Instrument [Line Items]
Interest Rate	2.85%	2.85%			2.98%
Extended maturity year	2029
Long-term debt	$ 633,699				$ 630,088
EUR 710.8 Million Seahawk 1 Term Loan
Debt Instrument [Line Items]
Interest Rate	3.69%	3.69%			3.92%
Extended maturity year	2030
Long-term debt	$ 695,843				$ 692,150
EUR 748.7 Million Seahawk 2 Term Loan
Debt Instrument [Line Items]
Interest Rate	3.71%	3.71%			3.92%
Extended maturity year	2031
Long-term debt	$ 860,212				$ 856,188
Leonardo Newbuild One Loan
Debt Instrument [Line Items]
Interest Rate	2.68%	2.68%			2.68%
Extended maturity year	2034
Long-term debt	$ 95,563				$ 48,009
Leonardo Newbuild Two Loan
Debt Instrument [Line Items]
Interest Rate	2.77%	2.77%			2.77%
Extended maturity year	2035
Long-term debt	$ 48,009				$ 48,009
Leonardo Newbuild Three Loan
Debt Instrument [Line Items]
Interest Rate	1.22%	1.22%			1.22%
Extended maturity year	2036
Long-term debt	$ 46,519				$ 42,700
Leonardo Newbuild Four Loan
Debt Instrument [Line Items]
Interest Rate	1.31%	1.31%			1.31%
Extended maturity year	2037
Long-term debt	$ 46,519				$ 42,700
Splendor Newbuild Loan
Debt Instrument [Line Items]
Interest Rate	2.97%	2.97%
Extended maturity year	2032
Long-term debt	$ 402,177
Explorer Newbuild Loan
Debt Instrument [Line Items]
Interest Rate	3.39%	3.39%			3.43%
Extended maturity year	2028
Long-term debt	$ 251,634				$ 242,449
Marina Newbuild Loan
Debt Instrument [Line Items]
Interest Rate	1.03%	1.03%			2.75%
Extended maturity year	2025
Long-term debt	$ 134,821				$ 156,319
Riviera Newbuild Loan
Debt Instrument [Line Items]
Interest Rate	0.96%	0.96%			2.48%
Extended maturity year	2024
Long-term debt	$ 203,038				$ 202,233
Term loan - newbuild related
Debt Instrument [Line Items]
Interest Rate	2.50%	2.50%	2.50%
Extended maturity year	2021
Long-term debt	$ 26,387	€ 21.6

Long-Term Debt - Summary of L_2

Long-Term Debt - Summary of Long-Term Debt (Parentheticals) (Details) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2020EUR (€)	Jul. 31, 2020USD ($)	May 31, 2020USD ($)	Apr. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019EUR (€)	Oct. 31, 2019USD ($)
$875 Million Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 875	$ 875
$75.0 Million Revolving Credit Line
Debt Instrument [Line Items]
Maximum borrowing capacity	75	75
$400.0 million L. Catterton exchangeable notes
Debt Instrument [Line Items]
Term loan amount	400				$ 400
Value of equity conversion options	623.2
Original issue discount	399.4
$862.5 million 6.000% exchangeable notes
Debt Instrument [Line Items]
Term loan amount	862.5				862.5
Value of equity conversion options	921
Original issue discount	$ 309.8
Interest rate	6.00%
$450.0 million 5.375% exchangeable notes
Debt Instrument [Line Items]
Term loan amount	$ 450			$ 450
Value of equity conversion options	311.9
Original issue discount	$ 142.4
Interest rate	5.375%
$675.0 million 12.25% senior secured notes
Debt Instrument [Line Items]
Term loan amount	$ 675
Original issue discount	$ 5.9
Interest rate	12.25%
$675 million senior secured revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity							$ 675		$ 675
$750.0 million 10.25% senior secured notes
Debt Instrument [Line Items]
Term loan amount	$ 750			$ 750
Interest rate	10.25%
Unsecured Notes
Debt Instrument [Line Items]
Term loan amount	$ 850
Interest rate	5.875%
$565.0 Million 3.625% Senior Unsecured Notes
Debt Instrument [Line Items]
Term loan amount	$ 565	$ 565
Interest rate	3.625%	3.625%
$260 Million Norwegian Jewel Term Loan
Debt Instrument [Line Items]
Term loan amount	$ 260	$ 260			$ 260
$230 Million Pride of America Term Loan
Debt Instrument [Line Items]
Term loan amount	$ 230					$ 230
EUR 529.8 million Breakaway one loan
Debt Instrument [Line Items]
Term loan amount | €			€ 529.8					€ 529.8
EUR 529.8 million Breakaway two loan
Debt Instrument [Line Items]
Term loan amount | €			529.8					529.8
EUR 590.5 million Breakaway three loan
Debt Instrument [Line Items]
Term loan amount | €			590.5					590.5
EUR 729.9 million Breakaway four loan
Debt Instrument [Line Items]
Term loan amount | €			729.9					729.9
EUR 710.8 Million Seahawk 1 Term Loan
Debt Instrument [Line Items]
Term loan amount | €			710.8					710.8
EUR 748.7 Million Seahawk 2 Term Loan
Debt Instrument [Line Items]
Term loan amount | €			€ 748.7					€ 748.7

Long-Term Debt (Details)

Long-Term Debt (Details) $ / shares in Units, € in Millions	Jan. 29, 2021USD ($)	May 08, 2020USD ($)	Apr. 20, 2020	Jan. 10, 2019USD ($)	Feb. 28, 2021USD ($)	Dec. 31, 2020USD ($)	Jul. 31, 2020USD ($)$ / shares	Jun. 30, 2020USD ($)	May 31, 2020USD ($)$ / shares	Apr. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Aug. 27, 2019item	Dec. 31, 2020USD ($)installment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020EUR (€)	Jul. 31, 2020EUR (€)	Dec. 31, 2019EUR (€)	Oct. 31, 2019USD ($)
Debt Instrument [Line Items]
Principal amount outstanding						$ 835,575,000							$ 835,575,000
Loss on extinguishment of debt		$ 5,000,000											10,480,000	$ 13,397,000	$ 6,346,000
Debt modification cost													$ 17,300,000
Number of trading days													20 days
Number of consecutive trading days													30 days
Long-term debt, reclassified						671,100,000							$ 671,100,000
Redemption price as a percentage of face amount													100.00%
Number of lawsuits filed | item												2
Interest expense, net													$ 520,100,000	272,900,000	270,400,000
Amortization of deferred financing costs													42,200,000	27,500,000	31,400,000
Loss on extinguishment of debt													27,800,000	16,700,000	$ 6,300,000
Accrued interest liability						101,900,000							$ 101,900,000	33,300,000
Minimum
Debt Instrument [Line Items]
Share price percentage on debt instrument													250.00%
Term Loan | Nordea Bank ABP
Debt Instrument [Line Items]
Principal amount				$ 230,000,000
Term Loan | LIBOR | Nordea Bank ABP
Debt Instrument [Line Items]
Description of variable rate basis				LIBOR
$875 Million Senior Secured Revolving Loan Facility
Debt Instrument [Line Items]
Principal amount outstanding						$ 875,000,000							$ 875,000,000
Interest rate						1.90%							1.90%			1.90%
Maximum borrowing capacity						$ 875,000,000							$ 875,000,000	875,000,000
$875 Million Senior Secured Revolving Loan Facility | Fourth Amended and Restated Credit Agreement | Revolving Loan Facility
Debt Instrument [Line Items]
Revolving Loan Facility											$ 875,000,000
New Term Loan A Facility
Debt Instrument [Line Items]
Principal amount outstanding						$ 1,536,417,000							$ 1,536,417,000	$ 1,565,512,000
Interest rate						1.93%							1.93%	3.06%		1.93%		3.06%
Export Credit Backed Securities
Debt Instrument [Line Items]
Principal amount outstanding										$ 386,000,000
Debt holiday period										12 months
Number of installments for amortization | installment													8
EUR 529.8 million Breakaway one loan
Debt Instrument [Line Items]
Principal amount | €																€ 529.8		€ 529.8
Principal amount outstanding						$ 307,529,000							$ 307,529,000	$ 305,969,000
Basis spread on variable rate			0.90%
Interest rate						1.15%							1.15%	2.84%		1.15%		2.84%
EUR 529.8 million Breakaway two loan
Debt Instrument [Line Items]
Principal amount | €																€ 529.8		€ 529.8
Principal amount outstanding						$ 343,214,000							$ 343,214,000	$ 370,531,000
Basis spread on variable rate			1.20%
Interest rate						3.90%							3.90%	4.10%		3.90%		4.10%
EUR 590.5 million Breakaway three loan
Debt Instrument [Line Items]
Principal amount | €																€ 590.5		€ 590.5
Principal amount outstanding						$ 481,085,000							$ 481,085,000	$ 478,665,000
Basis spread on variable rate			1.50%
Interest rate						2.83%							2.83%	2.98%		2.83%		2.98%
EUR 729.9 million Breakaway four loan
Debt Instrument [Line Items]
Principal amount | €																€ 729.9		€ 729.9
Principal amount outstanding						$ 633,699,000							$ 633,699,000	$ 630,088,000
Basis spread on variable rate			1.50%
Interest rate						2.85%							2.85%	2.98%		2.85%		2.98%
EUR 710.8 Million Seahawk 1 Term Loan
Debt Instrument [Line Items]
Principal amount | €																€ 710.8		€ 710.8
Principal amount outstanding						$ 695,843,000							$ 695,843,000	$ 692,150,000
Basis spread on variable rate			1.00%
Interest rate						3.69%							3.69%	3.92%		3.69%		3.92%
EUR 748.7 Million Seahawk 2 Term Loan
Debt Instrument [Line Items]
Principal amount | €																€ 748.7		€ 748.7
Principal amount outstanding						$ 860,212,000							$ 860,212,000	$ 856,188,000
Basis spread on variable rate			1.00%
Interest rate						3.71%							3.71%	3.92%		3.71%		3.92%
$230 Million Pride of America Term Loan
Debt Instrument [Line Items]
Principal amount						$ 230,000,000				$ 230,000,000			$ 230,000,000
Principal amount outstanding						$ 229,558,000							$ 229,558,000	$ 229,621,000
Interest rate						1.15%							1.15%	2.81%		1.15%		2.81%
$230 Million Pride of America Term Loan | Base rate loans
Debt Instrument [Line Items]
Basis spread on variable rate										0.75%
$230 Million Pride of America Term Loan | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate										1.75%
$675 million senior secured revolving credit facility
Debt Instrument [Line Items]
Revolving Loan Facility											675,000,000
Repayment of Epic credit facility							$ 675,000,000
Maximum borrowing capacity											$ 675,000,000								$ 675,000,000
$675 million senior secured revolving credit facility | Interest expense, net
Debt Instrument [Line Items]
Loss on extinguishment of debt													$ 5,500,000
$675 million senior secured revolving credit facility | Eurocurrency loans
Debt Instrument [Line Items]
Basis spread on variable rate											1.75%
$675 million senior secured revolving credit facility | Base rate loans
Debt Instrument [Line Items]
Basis spread on variable rate											0.75%
$675 million senior secured revolving credit facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate											0.80%
$260 Million Norwegian Jewel Term Loan
Debt Instrument [Line Items]
Principal amount						$ 260,000,000			$ 260,000,000				260,000,000	$ 260,000,000
Principal amount outstanding						$ 221,718,000							$ 221,718,000	$ 221,860,000
Interest rate						1.52%							1.52%	2.54%		1.52%		2.54%
Annual debt repayment rate									25
$260 Million Norwegian Jewel Term Loan | Eurocurrency loans
Debt Instrument [Line Items]
Basis spread on variable rate									2.50%
$260 Million Norwegian Jewel Term Loan | Base rate loans
Debt Instrument [Line Items]
Basis spread on variable rate									1.50%
$675.0 million 12.25% senior secured notes
Debt Instrument [Line Items]
Principal amount						$ 675,000,000							$ 675,000,000
Principal amount outstanding						$ 650,178,000			$ 675,000,000				$ 650,178,000
Percentage of threshold, after percentage									65.00%
Percentage of principal amount of debt redeemed									35.00%
Original issue discount and private offering percent									99.00%
Interest rate						12.25%			12.25%				12.25%			12.25%
Interest rate													12.25%
$675.0 million 12.25% senior secured notes | Debt Redemption Prior to February 15, 2024
Debt Instrument [Line Items]
Redemption price as a percentage of face amount									100.00%
$675.0 million 12.25% senior secured notes | Debt Redemption on or After February 15, 2024
Debt Instrument [Line Items]
Redemption price as a percentage of face amount									100.00%
$675.0 million 12.25% senior secured notes | Debt Redemption Prior to February 15, 2022
Debt Instrument [Line Items]
Redemption price as a percentage of face amount									112.25%
$750.0 million 10.25% senior secured notes
Debt Instrument [Line Items]
Principal amount						$ 750,000,000	$ 750,000,000						$ 750,000,000
Principal amount outstanding						$ 739,295,000							$ 739,295,000
Percentage of threshold, after percentage							65.00%
Percentage of principal amount of debt redeemed							35.00%
Interest rate						10.25%	10.25%						10.25%			10.25%	10.25%
Interest rate													10.25%
$750.0 million 10.25% senior secured notes | Debt Redemption On Or Prior To August 1, 2023
Debt Instrument [Line Items]
Redemption price as a percentage of face amount							110.25%
$750.0 million 10.25% senior secured notes | Debt Redemption Prior To August 1, 2023
Debt Instrument [Line Items]
Redemption price as a percentage of face amount							100.00%
Unsecured Notes
Debt Instrument [Line Items]
Principal amount						$ 850,000,000							$ 850,000,000
Principal amount outstanding						$ 837,659,000							$ 837,659,000
Interest rate						5.88%							5.88%			5.88%
Interest rate													5.875%
$862.5 million 6.000% exchangeable notes
Debt Instrument [Line Items]
Principal amount						$ 862,500,000			$ 862,500,000				$ 862,500,000
Principal amount outstanding						1,444,889,000							$ 1,444,889,000
Debt instrument amount									$ 1,000
Remaining discount amortization period													3 years 4 months 24 days
Value of equity conversion options						$ 921,000,000							$ 921,000,000
Interest rate						6.00%			6.00%				6.00%			6.00%
Effective interest rate						22.78%							22.78%			22.78%
Ordinary share exchange rate									72.7273
Initial exchange price | $ / shares									$ 13.75
Interest rate													6.00%
$862.5 million 6.000% exchangeable notes | Maximum
Debt Instrument [Line Items]
Ordinary share exchange rate									89.4454
$450.0 million 5.375% exchangeable notes
Debt Instrument [Line Items]
Principal amount						$ 450,000,000	$ 450,000,000						$ 450,000,000
Principal amount outstanding						608,645,000							$ 608,645,000
Debt instrument amount							$ 1,000
Remaining discount amortization period													4 years 7 months 6 days
Value of equity conversion options						$ 311,900,000							$ 311,900,000
Interest rate						5.38%	5.375%						5.38%			5.38%	5.375%
Effective interest rate						15.89%							15.89%			15.89%
Ordinary share exchange rate							53.3333
Initial exchange price | $ / shares							$ 18.75
Interest rate													5.375%
$450.0 million 5.375% exchangeable notes | Maximum
Debt Instrument [Line Items]
Ordinary share exchange rate							66.6666
Exchangeable Notes 2024 and Exchangeable Notes 2025 and Private Exchangeable Notes
Debt Instrument [Line Items]
Value of equity conversion options						$ 1,900,000,000							$ 1,900,000,000
$400.0 million L. Catterton exchangeable notes
Debt Instrument [Line Items]
Principal amount						400,000,000			$ 400,000,000				400,000,000
Principal amount outstanding						638,185,000							$ 638,185,000
Debt instrument amount									$ 1,000
Remaining discount amortization period													5 years 4 months 24 days
Value of equity conversion options						$ 623,200,000							$ 623,200,000
Interest rate						7.00%							7.00%			7.00%
Ordinary share exchange rate									82.6446
Initial exchange price | $ / shares									$ 12.10
$400.0 million L. Catterton exchangeable notes | Maximum
Debt Instrument [Line Items]
Ordinary share exchange rate									90.9090
$400.0 million L. Catterton exchangeable notes | Debt Instrument First Year Post Issuance
Debt Instrument [Line Items]
Interest rate									7.00%
Deferred Loans | Supplemental Agreements
Debt Instrument [Line Items]
Annual debt repayment rate								25
Deferred Term A Loans | Fifth Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Percentage of outstanding loans held by lender		87.57%
Annual debt repayment rate		25
Deferred Term A Loans | Fifth Amended and Restated Credit Agreement | Eurocurrency loans
Debt Instrument [Line Items]
Basis spread on variable rate		2.50%
Deferred Term A Loans | Fifth Amended and Restated Credit Agreement | Base rate loans
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Deferred Term A Loans | Supplemental Agreements
Debt Instrument [Line Items]
Principal amount outstanding								$ 156,000,000
Explorer Newbuild Loan
Debt Instrument [Line Items]
Principal amount outstanding						$ 251,634,000							$ 251,634,000	$ 242,449,000
Interest rate						3.39%							3.39%	3.43%		3.39%		3.43%
Explorer Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate								2.80%
Splendor Newbuild Loan
Debt Instrument [Line Items]
Principal amount outstanding						$ 402,177,000							$ 402,177,000
Interest rate						2.97%							2.97%			2.97%
Splendor Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate								1.75%
Marina Newbuild Loan
Debt Instrument [Line Items]
Principal amount outstanding						$ 134,821,000							$ 134,821,000	$ 156,319,000
Interest rate						1.03%							1.03%	2.75%		1.03%		2.75%
Marina Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate								0.55%
Riviera Newbuild Loan
Debt Instrument [Line Items]
Principal amount outstanding						$ 203,038,000							$ 203,038,000	$ 202,233,000
Interest rate						0.96%							0.96%	2.48%		0.96%		2.48%
Riviera Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate								0.55%
Term loan - newbuild related
Debt Instrument [Line Items]
Principal amount | €																	€ 31.2
Principal amount outstanding						$ 26,387,000							$ 26,387,000			€ 21.6
Interest rate						2.50%	2.50%						2.50%			2.50%	2.50%
5.875% senior unsecured notes | Unsecured Notes
Debt Instrument [Line Items]
Principal amount						$ 850,000,000							$ 850,000,000
Percentage of threshold, after percentage						60.00%
Percentage of principal amount of debt redeemed						40.00%
Interest rate						5.875%
5.875% senior unsecured notes | Debt Redemption Prior To December 15, 2025 | Unsecured Notes
Debt Instrument [Line Items]
Redemption price as a percentage of face amount						100.00%
5.875% senior unsecured notes | Debt Redemption On Or After December 15, 2025 | Unsecured Notes
Debt Instrument [Line Items]
Redemption price as a percentage of face amount						100.00%
5.875% senior unsecured notes | Debt Redemption Prior To December 15, 2022 | Unsecured Notes
Debt Instrument [Line Items]
Redemption price as a percentage of face amount						105.875%
Subsequent Event | First Amendment
Debt Instrument [Line Items]
Covenant, minimum liquidity	$ 200,000,000
Subsequent Event | Second Deferral Period [Member]
Debt Instrument [Line Items]
Annual debt repayment rate					20
Subsequent Event | Covenant Relief Period December 31, 2022 | First Amendment | Base rate loans
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Subsequent Event | Covenant Relief Period December 31, 2022 | First Amendment | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
Subsequent Event | EUR 529.8 million Breakaway one loan
Debt Instrument [Line Items]
Principal amount					$ 529,800,000
Subsequent Event | EUR 529.8 million Breakaway one loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.10%
Subsequent Event | EUR 529.8 million Breakaway two loan
Debt Instrument [Line Items]
Principal amount					$ 529,800,000
Subsequent Event | EUR 529.8 million Breakaway two loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.40%
Subsequent Event | EUR 590.5 million Breakaway three loan
Debt Instrument [Line Items]
Principal amount					$ 590,500,000
Subsequent Event | EUR 590.5 million Breakaway three loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.50%
Subsequent Event | EUR 729.9 million Breakaway four loan
Debt Instrument [Line Items]
Principal amount					$ 729,900,000
Subsequent Event | EUR 729.9 million Breakaway four loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.50%
Subsequent Event | EUR 710.8 Million Seahawk 1 Term Loan
Debt Instrument [Line Items]
Principal amount					$ 710,800,000
Subsequent Event | EUR 710.8 Million Seahawk 1 Term Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.20%
Subsequent Event | EUR 748.7 Million Seahawk 2 Term Loan
Debt Instrument [Line Items]
Principal amount					$ 748,700,000
Subsequent Event | EUR 748.7 Million Seahawk 2 Term Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.20%
Subsequent Event | Deferred Loans
Debt Instrument [Line Items]
Deferred amortization payments					$ 680,000,000
Covenant, minimum liquidity	$ 200,000,000
Subsequent Event | Explorer Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					3.00%
Subsequent Event | Splendor Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					1.95%
Subsequent Event | Marina Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					0.75%
Subsequent Event | Riviera Newbuild Loan | Six months LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate					0.75%
Subsequent Event | Deferred Term A-1 Loans | First Amendment
Debt Instrument [Line Items]
Annual debt repayment rate	25
Subsequent Event | Deferred Term A-1 Loans | Eurocurrency loans | First Amendment | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
Subsequent Event | Deferred Term A-1 Loans | Base rate loans | First Amendment
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
Subsequent Event | Term A-2 Loans | First Amendment
Debt Instrument [Line Items]
Annual debt repayment rate	5.88
Subsequent Event | Deferred Term Loan A-1 And Term Loan A-2 | First Amendment
Debt Instrument [Line Items]
Deferred amortization payments	$ 70,000,000
Accrete to principle | $400.0 million L. Catterton exchangeable notes | Debt Instrument Four Years Following First Year Post Issuance
Debt Instrument [Line Items]
Interest rate									4.50%
Cash interest | $400.0 million L. Catterton exchangeable notes | Debt Instrument Four Years Following First Year Post Issuance
Debt Instrument [Line Items]
Interest rate									3.00%
Cash interest | $400.0 million L. Catterton exchangeable notes | Debt Instrument Final Year Prior To Maturity
Debt Instrument [Line Items]
Interest rate									7.50%

Long-Term Debt - Liability Comp

Long-Term Debt - Liability Components of Exchangeable Notes (Details) $ in Thousands	Dec. 31, 2020USD ($)
Long-term Debt, Unclassified [Abstract]
Principal amount	$ 1,726,811
Less: Unamortized debt discount, including deferred financing fees	(891,236)
Net carrying value	$ 835,575

Long-Term Debt - Interest Expen

Long-Term Debt - Interest Expense Related to the Exchangeable Notes (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Long-term Debt, Unclassified [Abstract]
Interest expense, including amortization of debt discounts and coupon interest	$ 130,949

Long-Term Debt - Summary of Sch

Long-Term Debt - Summary of Scheduled Principal Repayments on Long-Term Debt Including Finance Lease Obligations (Details) $ in Thousands	Dec. 31, 2020USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
2021	$ 124,829
2022	1,192,923
2023	917,893
2024	5,051,867
2025	1,045,773
Thereafter	3,818,798
Total	$ 12,152,083

Related Party Disclosures (Deta

Related Party Disclosures (Details) - shares	May 28, 2020	Dec. 31, 2020
$400.0 million L. Catterton exchangeable notes | Maximum
Related Party Transaction [Line Items]
Shares issuable upon exchange	46,577,947
L Catterton [Member]
Related Party Transaction [Line Items]
Beneficial ownership		10.00%
L Catterton [Member] | Minimum
Related Party Transaction [Line Items]
Investor ownership threshold	50.00%

Fair Value Measurements and D_3

Fair Value Measurements and Derivatives - Derivatives Measured at Fair Value and Discloses Balance Sheet Location (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	$ 49,029	$ 277
Derivative liabilities, fair value	1,998,275	192,034
Derivatives
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	56,396	3,429
Derivative liabilities, fair value	1,998,275	192,034
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	55,850	3,429
Derivative liabilities, fair value	131,864	192,034
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	546
Derivative liabilities, fair value	1,866,411
Fuel swaps | Designated as Hedging Instrument | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets, fair value		277
Fuel swaps | Designated as Hedging Instrument | Accrued expenses and other liabilities
Derivatives, Fair Value [Line Items]
Derivative assets, fair value		2,300
Derivative liabilities, fair value	35,973	18,257
Fuel swaps | Designated as Hedging Instrument | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative assets, fair value		683
Derivative liabilities, fair value	28,947	17,763
Fuel swaps | Not Designated as Hedging Instrument | Accrued expenses and other liabilities
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	546
Derivative liabilities, fair value	6,732
Fuel swaps | Not Designated as Hedging Instrument | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	3,534
Foreign Currency Forward Contracts | Designated as Hedging Instrument | Prepaid expenses and other assets
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	5,779
Foreign Currency Forward Contracts | Designated as Hedging Instrument | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	43,250
Foreign Currency Forward Contracts | Designated as Hedging Instrument | Accrued expenses and other liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	14,778	33,475
Foreign Currency Forward Contracts | Designated as Hedging Instrument | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative assets, fair value	6,821	169
Derivative liabilities, fair value	44,938	118,500
Interest rate contracts | Designated as Hedging Instrument | Accrued expenses and other liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	6,776	2,178
Interest rate contracts | Designated as Hedging Instrument | Other long-term liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	452	$ 1,861
Debt Conversion Options | Not Designated as Hedging Instrument | Exchangeable Notes
Derivatives, Fair Value [Line Items]
Derivative liabilities, fair value	$ 1,856,145

Fair Value Measurements and D_4

Fair Value Measurements and Derivatives - Amounts Recognized within Assets and Liabilities Based on Right of Offset (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Gross Amounts, Assets	$ 49,029	$ 277
Total Net Amounts, Assets	49,029	277
Gross Amounts Not Offset, Assets	(49,029)
Net Amounts, Assets		277
Gross Amounts, Liabilities	1,998,275	192,034
Gross Amounts Offset, Liabilities	(7,367)	(3,152)
Total Net Amounts, Liabilities	1,990,908	188,882
Gross Amount Not Offset, Liabilities	(1,913,496)	(149,863)
Net Amounts, Liabilities	$ 77,412	$ 39,019

Fair Value Measurements and D_5

Fair Value Measurements and Derivatives - Effects of Derivatives Designated as Cash Flow Hedges (Details) - Cash Flow Hedging - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	$ (51,642)	$ (123,015)	$ (161,214)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(106,670)	8,898	30,096
Fuel
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(45,488)	14,093	34,410
Depreciation and amortization
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(4,929)	(3,062)	(3,463)
Interest expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(6,600)	(2,133)	(851)
Other Income (Expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(49,653)
Fuel swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	(157,669)	46,154	(52,949)
Fuel swaps | Fuel
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(45,488)	14,093	34,410
Foreign Currency Forward Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	116,496	(163,197)	(108,911)
Foreign Currency Forward Contracts | Depreciation and amortization
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(4,929)	(3,062)	(3,463)
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	(10,469)	(5,972)	646
Interest rate contracts | Interest expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	$ (6,600)	$ (2,133)	$ (851)

Fair Value Measurements and D_6

Fair Value Measurements and Derivatives - Effects of Cash Flow Hedge Accounting on Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Fuel	$ 264,712	$ 409,602	$ 392,685
Depreciation and amortization	717,840	646,188	561,060
Interest expense, net	520,063	272,867	270,404
Other income (expense), net	(984,501)	6,155	20,653
Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Fuel	264,712	409,602	392,685
Depreciation and amortization	717,840	646,188	561,060
Interest expense, net	520,063	272,867	270,404
Other income (expense), net	(984,501)
Amount of Gain (Loss) Recognized in Other Comprehensive Income	(51,642)	(123,015)	(161,214)
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(106,670)	8,898	30,096
Cash Flow Hedging | Fuel
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(45,488)	14,093	34,410
Cash Flow Hedging | Depreciation and amortization
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(4,929)	(3,062)	(3,463)
Cash Flow Hedging | Interest expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(6,600)	(2,133)	(851)
Cash Flow Hedging | Other Income (Expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(49,653)
Cash Flow Hedging | Fuel swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	(157,669)	46,154	(52,949)
Cash Flow Hedging | Fuel swaps | Fuel
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(45,488)	14,093	34,410
Cash Flow Hedging | Fuel swaps | Other Income (Expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from accumulated other comprehensive income (loss) into income as a result that a forecasted transaction is no longer probable of occurring	(49,653)
Amount of gain recognized in income as a result of failing effectiveness tests	5,507
Cash Flow Hedging | Foreign Currency Forward Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	116,496	(163,197)	(108,911)
Cash Flow Hedging | Foreign Currency Forward Contracts | Depreciation and amortization
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	(4,929)	(3,062)	(3,463)
Cash Flow Hedging | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Other Comprehensive Income	(10,469)	(5,972)	646
Cash Flow Hedging | Interest rate contracts | Interest expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income (Loss) into Income	$ (6,600)	$ (2,133)	$ (851)

Fair Value Measurements and D_7

Fair Value Measurements and Derivatives - Effects of Derivatives Not Designated as Hedging Instruments (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Not Designated as Hedging Instrument | Fuel swaps | Other Income (Expense), net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ 20,932

Fair Value Measurements and D_8

Fair Value Measurements and Derivatives (Details) T in Thousands, $ in Millions, € in Billions	12 Months Ended
	Dec. 31, 2020EUR (€)T	Dec. 31, 2020USD ($)T	Nov. 01, 2020T	Dec. 31, 2019USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt		$ 14,197.8		$ 6,957.8
Fair value of long-term debt in excess of carrying value		$ 1,047		$ 31.3
Fuel Swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative maturing date	Dec. 31, 2023
Projected fuel purchases | T	596	596
Interest rate contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notional amount of derivatives		$ 700
Foreign Currency Forward Contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notional amount of derivatives	€ 1.9	$ 2,300
Not Designated as Hedging Instrument | Fuel Swaps
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative maturing date	Sep. 30, 2021
Projected fuel purchases | T	89	89
Not Designated as Hedging Instrument | Fuel Hedge
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative maturing date	Dec. 31, 2022
Projected fuel purchases | T			197
NCLH | $862.5 million 6.000% exchangeable notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notional amount of derivatives		$ 62.7
NCLH | $450.0 million 5.375% exchangeable notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notional amount of derivatives		24
NCLH | $400.0 million L. Catterton exchangeable notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notional amount of derivatives		$ 34.2

Employee Benefits and Share-B_3

Employee Benefits and Share-Based Compensation - Summary of Assumptions Used Within Option-Pricing Model (Details) - Performance-Based Options	12 Months Ended
	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%
Expected stock price volatility, minimum	31.50%
Expected stock price volatility, maximum	32.20%
Risk-free interest rate, minimum	2.48%
Risk-free interest rate, maximum	2.58%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	3 years 8 months 19 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	4 years 2 months 19 days

Employee Benefits and Share-B_4

Employee Benefits and Share-Based Compensation - Summary of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Weighted-Average Contractual Term (Years)
Outstanding as of December 31, 2019	4 years 5 months 1 day	5 years 5 months 1 day
Vested and expected to vest as of December 31, 2019	4 years 5 months 1 day
Exercisable as of December 31, 2019	4 years 5 months 1 day
Aggregate Intrinsic Value
Outstanding as of December 31, 2019	$ 0	$ 33,413
Vested and expected to vest as of December 31, 2019	0
Exercisable as of December 31, 2019	$ 0
Time-Based Awards
Number of Share Option Awards
Outstanding as of January 1, 2019	4,918,554
Exercised	(48,221)
Forfeited and cancelled	(345,126)
Outstanding as of December 31, 2019	4,525,207	4,918,554
Vested and expected to vest as of December 31, 2019	4,525,207
Exercisable as of December 31, 2019	4,525,207
Weighted-Average Exercise Price
Outstanding as of January 1, 2019	$ 51.84
Exercised	44.38
Forfeited and cancelled	51.24
Outstanding as of December 31, 2019	51.96	$ 51.84
Vested and expected to vest as of December 31, 2019	51.96
Exercisable as of December 31, 2019	$ 51.96
Performance-Based Options
Number of Share Option Awards
Outstanding as of January 1, 2019	115,489
Granted	0
Exercised	(906)
Outstanding as of December 31, 2019	114,583	115,489
Vested and expected to vest as of December 31, 2019	114,583
Exercisable as of December 31, 2019	114,583
Weighted-Average Exercise Price
Outstanding as of January 1, 2019	$ 59.11
Exercised	19
Outstanding as of December 31, 2019	59.43	$ 59.11
Vested and expected to vest as of December 31, 2019	59.43
Exercisable as of December 31, 2019	$ 59.43
Market-Based Awards
Number of Share Option Awards
Outstanding as of January 1, 2019	208,333
Exercised	0
Forfeited and cancelled	0
Outstanding as of December 31, 2019	208,333	208,333
Vested and expected to vest as of December 31, 2019	0
Exercisable as of December 31, 2019	0
Weighted-Average Exercise Price
Outstanding as of January 1, 2019	$ 59.43
Exercised	0
Forfeited and cancelled	0
Outstanding as of December 31, 2019	59.43	$ 59.43
Vested and expected to vest as of December 31, 2019	0
Exercisable as of December 31, 2019	$ 0

Employee Benefits and Share-B_5

Employee Benefits and Share-Based Compensation - Summary of Restricted Share Units (Details) - Restricted Share Units - NCLH	12 Months Ended
	Dec. 31, 2020$ / sharesshares
Time-Based Awards
Number of Restricted Share
Non-vested as of January 1, 2019 | shares	3,245,625
Restricted share unit awards granted | shares	5,380,123
Vested | shares	(1,610,315)
Forfeited or expired | shares	(351,508)
Non-vested as of December 31, 2019 | shares	6,663,925
Non-vested and expected to vest as of December 31, 2019 | shares	6,663,925
Weighted-Average Grant-Date Fair Value
Non-vested as of January 1, 2019 | $ / shares	$ 54.94
Granted | $ / shares	23.69
Vested | $ / shares	54.01
Forfeited or expired | $ / shares	43.53
Non-vested as of December 31, 2019 | $ / shares	30.54
Non-vested and expected to vest as of December 31, 2019 | $ / shares	$ 30.54
Performance-Based RSU Awards
Number of Restricted Share
Non-vested as of January 1, 2019 | shares	1,129,396
Restricted share unit awards granted | shares	945,598
Vested | shares	(192,523)
Forfeited or expired | shares	(317,287)
Non-vested as of December 31, 2019 | shares	1,565,184
Non-vested and expected to vest as of December 31, 2019 | shares	981,098
Weighted-Average Grant-Date Fair Value
Non-vested as of January 1, 2019 | $ / shares	$ 56.09
Granted | $ / shares	27.75
Vested | $ / shares	56.27
Forfeited or expired | $ / shares	53.72
Non-vested as of December 31, 2019 | $ / shares	39.42
Non-vested and expected to vest as of December 31, 2019 | $ / shares	$ 41.71
Market-Based RSUs
Number of Restricted Share
Non-vested as of January 1, 2019 | shares	50,000
Restricted share unit awards granted | shares	0
Vested | shares	0
Forfeited or expired | shares	0
Non-vested as of December 31, 2019 | shares	50,000
Non-vested and expected to vest as of December 31, 2019 | shares	0
Weighted-Average Grant-Date Fair Value
Non-vested as of January 1, 2019 | $ / shares	$ 59.43
Granted | $ / shares	0
Vested | $ / shares	0
Forfeited or expired | $ / shares	0
Non-vested as of December 31, 2019 | $ / shares	59.43
Non-vested and expected to vest as of December 31, 2019 | $ / shares	$ 0

Employee Benefits and Share-B_6

Employee Benefits and Share-Based Compensation - Summary of Compensation Expense Recognized for Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 111,297	$ 95,055	$ 115,983
Payroll and related
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	21,190	17,597	15,629
Marketing, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 90,107	$ 77,458	$ 100,354

Employee Benefits and Share-B_7

Employee Benefits and Share-Based Compensation - Amounts Related to Shipboard Retirement Plan (Details) - Shipboard Retirement Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension expense:
Service cost	$ 2,665	$ 2,135	$ 2,167
Interest cost	895	1,001	857
Amortization of prior service cost	378	378	378
Amortization of actuarial loss	29		51
Total pension expense	3,967	3,514	3,453
Change in projected benefit obligation:
Projected benefit obligation at beginning of year	28,695	24,318	24,587
Service cost	2,665	2,135	2,167
Interest cost	895	1,001	857
Actuarial gain (loss)	62	2,308	(2,271)
Direct benefit payments	(698)	(1,067)	(1,022)
Projected benefit obligation at end of year	31,619	28,695	24,318
Amounts recognized in the consolidated balance sheets:
Projected benefit obligation	31,619	28,695	24,318
Amounts recognized in accumulated other comprehensive income (loss):
Prior service cost	(3,403)	(3,781)	(4,159)
Accumulated actuarial loss	(3,446)	(3,413)	(1,105)
Accumulated other comprehensive income (loss)	$ (6,849)	$ (7,194)	$ (5,264)

Employee Benefits and Share-B_8

Employee Benefits and Share-Based Compensation - Pension Benefits Expected to be Paid (Details) $ in Thousands	Dec. 31, 2020USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
2021	$ 918
2022	989
2023	1,118
2024	1,224
2025	1,339
Next five years	$ 11,004

Employee Benefits and Share-B_9

Employee Benefits and Share-Based Compensation (Details) - USD ($)	Jul. 27, 2020	Mar. 02, 2020	May 31, 2016	Jan. 31, 2013	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised					$ 600,000	$ 13,300,000	$ 16,700,000
Proceeds from the exercise of share options					2,200,000	28,300,000	25,800,000
Unrecognized compensation cost					0
Payments related to tax withholding for share-based compensation					$ 15,407,000	$ 20,939,000	$ 13,855,000
Time-Based Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share option awards granted					0	0	0
Time-Based Options | Restated 2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of share-based awards vesting period			The vesting period for time-based options is typically set at three, four or five years with a contractual life ranging from seven to 10 years.
Performance-Based Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share option awards granted					0
Weighted-average grant-date fair value of options granted							$ 15.20
Performance-Based Options | Restricted Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to restricted share unit awards					$ 6,100,000
Weighted-average period for recognition of unrecognized compensation expense					1 year
Market-Based Option Awards | Restricted Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to restricted share unit awards					$ 0
Weighted-average period for recognition of unrecognized compensation expense					0 years
Time-Based Awards | Employee | Awarded on July 27, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share unit awards granted	2,500,000
Time-Based Awards | Restricted Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to restricted share unit awards					$ 127,800,000
Weighted-average period for recognition of unrecognized compensation expense					1 year 8 months 12 days
Performance-Based RSU Awards | Members of management team | Awarded on July 27, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share unit awards granted	300,000
Performance-Based RSU Awards | Members of management team | Awarded on March 2, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share unit awards granted		600,000
Restricted Share Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based award, vesting period					3 years
NCLH | Restated 2013 Performance Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares authorized				15,035,106
Maximum number of shares that can be granted to one individual				5,000,000
Number of additional shares authorized			12,430,000
Maximum number of shares that can be granted			27,465,106
NCLH | Time-Based Options | Restated 2013 Performance Incentive Plan | Employee | Option Vesting Period, Three Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based award, vesting period			3 years
NCLH | Time-Based Options | Restated 2013 Performance Incentive Plan | Employee | Option Vesting Period, Four Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based award, vesting period			4 years
NCLH | Time-Based Options | Restated 2013 Performance Incentive Plan | Employee | Option Vesting Period, Five Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based award, vesting period			5 years
NCLH | Time-Based Options | Restated 2013 Performance Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of shares granted			7 years
NCLH | Time-Based Options | Restated 2013 Performance Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of shares granted			10 years
NCLH | Time-Based Awards | Employee | Awarded on March 2, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share unit awards granted		2,400,000
Share-based award, vesting period		3 years

Employee Benefits and Share-_10

Employee Benefits and Share-Based Compensation 2 (Details) - USD ($) $ in Thousands	Mar. 02, 2020	Apr. 30, 2014	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Share-based compensation expense			$ 111,297	$ 95,055	$ 115,983
Maximum percentage of employee eligible compensation that may be contributed towards 401(k) Plan			100.00%
Forfeited contributions utilized			$ 200	$ 200	$ 300
Discount rates used in net periodic benefit cost calculation			3.20%	4.20%	3.60%
Amortization period of actuarial loss			18 years 6 months 25 days
Employee Stock Purchase Plan
Defined Benefit Plan Disclosure [Line Items]
Recorded expenses related to 401(k) Plan			$ 2,800	$ 9,100	$ 9,300
Percentage of purchase price discount		15.00%
Accrued payroll liability			$ 1,400	2,100
Employee Stock Purchase Plan | Maximum
Defined Benefit Plan Disclosure [Line Items]
Share options and ordinary shares, authorized		2,000,000
First 3% of each participant's contributions
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution percent			100.00%
Defined contribution plan, percentage of employee contribution			3.00%
Greater than 3% of each participants contribution
Defined Benefit Plan Disclosure [Line Items]
Employer matching contribution percent			50.00%
Greater than 3% of each participants contribution | Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, percentage of employee contribution			3.00%
Greater than 3% of each participants contribution | Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, percentage of employee contribution			10.00%
Shipboard Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Plan assets			$ 0
Projected benefit obligation included in accrued expenses and other liabilities			900
Projected benefit obligation included in other long-term liabilities			$ 30,700	$ 27,800
NCLH | Time-Based Awards | Employee | Awarded on March 2, 2020
Defined Benefit Plan Disclosure [Line Items]
Share-based award, vesting period	3 years

Income Taxes - Components of Ne

Income Taxes - Components of Net Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Components Of Net Income Before Income Taxes [Line Items]
Net income (loss) before income taxes	$ (4,986,613)	$ 914,001	$ 974,172
Bermuda
Components Of Net Income Before Income Taxes [Line Items]
Net income (loss) before income taxes	0	0	0
Foreign - Other
Components Of Net Income Before Income Taxes [Line Items]
Net income (loss) before income taxes	$ (4,986,613)	$ 914,001	$ 974,172

Income Taxes - Components of th

Income Taxes - Components of the Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
United States	$ (326)	$ 837	$ (836)
Total current:	(5,828)	(5,457)	(6,207)
Deferred:
United States	(15,613)	32,315	(2,001)
Total deferred:	(15,742)	32,662	(1,775)
Income tax benefit (expense)	(21,570)	27,205	(7,982)
Bermuda
Current:
Foreign	0	0	0
Deferred:
Foreign	0	0	0
Foreign - Other
Current:
Foreign	(5,502)	(6,294)	(5,371)
Deferred:
Foreign	$ (129)	$ 347	$ 226

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense Computed by Applying our Bermuda Statutory Rate and Reported Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Tax at Bermuda statutory rate	$ 0	$ 0	$ 0
Foreign income taxes at different rates	17,051	(9,819)	(11,119)
Tax contingencies	(626)	(206)	(6)
Return to provision adjustments	9	1,538	3,055
Benefit (expense) from change in tax rate	0	(7)	88
Valuation allowance	(38,004)	35,699	0
Income tax benefit (expense)	$ (21,570)	$ 27,205	$ (7,982)

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Loss carryforwards	$ 77,093	$ 54,122
Other	4,561	2,356
Valuation allowance	(42,876)	(5,847)
Total net deferred assets	38,778	50,631
Deferred tax liabilities:
Property and equipment	(36,463)	(34,724)
Total deferred tax liabilities	(36,463)	(34,724)
Net deferred tax asset (liability)	$ 2,315	$ 15,907

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of the Total Amounts of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning of the year	$ 732	$ 532
Gross increases in tax positions from prior periods	620	200
Unrecognized tax benefits, end of year	$ 1,352	$ 732

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Valuation allowance	$ 42,876	$ 5,847
Unrecognized tax benefits	1,352	732		$ 532
Tax benefit connection with the reversal of substantially all of valuation allowance on net operating loss carryforwards			$ 35,700
Prestige Cruises International Inc
Income Taxes [Line Items]
Net operating loss carryforwards	$ 155,000	145,000
U.S. federal and state net operating loss carryforwards, expiration year	2030
Operating loss carryforwards increase in ownership percentage	50.00%
Operating loss carryforwards, expiration period	3 years
Tax benefit connection with the reversal of substantially all of valuation allowance on net operating loss carryforwards	$ 30,000
NORWAY
Income Taxes [Line Items]
Net operating loss carryforwards	13,400	13,300
U.K
Income Taxes [Line Items]
Net operating loss carryforwards	0	5,500
U.S
Income Taxes [Line Items]
Valuation allowance	39,600
NCLC
Income Taxes [Line Items]
Net operating loss carryforwards	$ 352,900	$ 238,800
U.S. federal and state net operating loss carryforwards, expiration year	2030

Commitments and Contingencies_2

Commitments and Contingencies (Details) € in Millions, £ in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Aug. 27, 2019item	Dec. 31, 2020USD ($)	Dec. 31, 2020EUR (€)item	Dec. 31, 2020USD ($)item	Dec. 31, 2020GBP (£)item
Commitments and Contingencies Disclosure [Line Items]
Number of cruise ships			28	28	28
Number of additional ships			9	9	9
Capacity of ship, berths			59,150	59,150	59,150
Advance ticket sales with credit card processor | $				$ 1,000
Reserves maintained credit card processor | $				200
Cash collateral provided for credit card processors | $				250
Percentage of funding of incoming advance ticket sale deposit		100.00%
Exposure amount of credit card processor | $				$ 780
Amount of shortfall in credit card processor reserve | $		$ 330
Number of lawsuits filed	2
Ship to be delivered in 2023
Commitments and Contingencies Disclosure [Line Items]
Number of additional ships			1	1	1
Ships launching period in 2022 through 2027 | Project Leonardo
Commitments and Contingencies Disclosure [Line Items]
Number of additional ships			6	6	6
Ship Construction Contracts
Commitments and Contingencies Disclosure [Line Items]
Aggregate contract price of new ships based on the euro/U.S. dollar exchange rate			€ 7,100	$ 8,700
Export credit facility financing as percentage of contract price			80.00%	80.00%	80.00%
Ship Construction Contracts | Ship order delivery in 2022 and 2025
Commitments and Contingencies Disclosure [Line Items]
Number of additional ships			2	2	2
Capacity of ship, tons			67,000	67,000	67,000
Capacity of ship, berths			1,200	1,200	1,200
Ship Construction Contracts | Ship order delivery in winter 2020 | Explorer Class Ship And Seas Splendor
Commitments and Contingencies Disclosure [Line Items]
Capacity of ship, tons			55,000	55,000	55,000
Capacity of ship, berths			750	750	750
Ship Construction Contracts | Ships launching period in 2022 through 2027 | Project Leonardo | Minimum
Commitments and Contingencies Disclosure [Line Items]
Capacity of ship, tons			140,000	140,000	140,000
Capacity of ship, berths			3,300	3,300	3,300
Ship Construction Contracts | Ships launching period in 2022 through 2027 | Project Leonardo | Maximum
Commitments and Contingencies Disclosure [Line Items]
Capacity of ship, tons			156,300	156,300	156,300
Capacity of ship, berths			3,550	3,550	3,550
Other Commitments
Commitments and Contingencies Disclosure [Line Items]
Performance guarantee required to be maintained | $				$ 32
Security guarantee | £					£ 39.3
Consumer coverage | €			€ 48.3
Amount of cash to secure financial security | $		$ 30.5

Commitments and Contingencies -

Commitments and Contingencies - Minimum Annual Payments for Non-Cancelable Ship Construction Contracts (Details) - Ship Construction Contracts - USD ($) $ in Thousands	Feb. 27, 2021	Dec. 31, 2020
Other Commitments [Line Items]
2021		$ 463,549
2022		1,118,430
2023		2,168,127
2024		1,092,766
2025		1,758,314
Thereafter		1,870,807
Total		$ 8,471,993
Payments deferred	$ 194,100
Financing commitment	$ 35,200

Commitments and Contingencies_3

Commitments and Contingencies - Future Commitments to Pay for Usage of Port Facilities (Details) - Port Facility Commitments $ in Thousands	Dec. 31, 2020USD ($)
Other Commitments [Line Items]
2021	$ 71,691
2022	71,296
2023	71,460
2024	75,822
2025	70,132
Thereafter	1,707,376
Total	$ 2,067,777

Other Income (Expense), Net (De

Other Income (Expense), Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Income and Expenses [Abstract]
Other income (expense), net	$ (984,501)	$ 6,155	$ 20,653

Concentration Risk (Details)

Concentration Risk (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplier Concentration Risk
Concentration Risk [Line Items]
Expenses incurred on hotel and restaurant services	$ 59	$ 153.6	$ 153.7

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Non-cash investing activity in connection with property and equipment	$ 17.7
Non-cash investing activity in connection with property and equipment, seller financing	11.9	$ 8.2	$ 39.7
Income taxes paid	2.9	8.7	10
Interest and related fees	$ 447.9	$ 291.2	$ 350.4

Quarterly Selected Financial _3

Quarterly Selected Financial Data (Unaudited) (in thousands) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 9,579	$ 6,518	$ 16,929	$ 1,246,882	$ 1,480,618	$ 1,913,851	$ 1,664,277	$ 1,403,630	$ 1,279,908	$ 6,462,376	$ 6,055,126
Operating income	(546,755)	(517,478)	(594,537)	(1,823,279)	199,878	512,337	309,594	158,904	(3,482,049)	1,180,713	1,223,923
Net income (loss)	$ (1,416,700)	$ (758,152)	$ (951,065)	$ (1,882,266)	$ 123,217	$ 455,309	$ 243,276	$ 119,404	$ (5,008,183)	$ 941,206	$ 966,190

Schedule II Valuation and Qua_2

Schedule II Valuation and Qualifying Accounts (Details) - Valuation allowance on deferred tax assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance	$ 5,847	$ 41,924	$ 42,154
Additions Charged to other accounts	38,150		276
Deductions	(1,121)	(36,077)	(506)
Balance	$ 42,876	$ 5,847	$ 41,924