Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Nov. 30, 2017
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Presentation These Consolidated Financial Statements are presented in United States dollars and have been prepared in accordance with accounting principles generally accepted in the United States (US GAAP). References in these Consolidated Financial Statements and Notes to $ refer to United States dollars and C$ to Canadian dollars. Dollar amounts are in thousands, except for per share amounts.
Use of Estimates, Policy [Policy Text Block]	Use of estimates The preparation of the Company’s Consolidated Financial Statements in accordance with US GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements and the reported amounts of expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions include: investments in affiliates; mineral properties; income taxes; and share-based compensation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances. Actual results could differ from the amounts estimated in these Consolidated Financial Statements.
Consolidation, Policy [Policy Text Block]	Principles of consolidation The Company’s Consolidated Financial Statements include NOVAGOLD RESOURCES INC. and its wholly-owned subsidiaries. The Company’s wholly-owned subsidiaries include NOVAGOLD Canada Inc., Copper Canyon Resources Ltd., NOVAGOLD U.S. Holdings Inc., NOVAGOLD Resources Alaska Inc., NOVAGOLD USA, Inc., and AGC Resources Inc. All inter-company transactions and balances are eliminated on consolidation. The functional currency for the Company’s Canadian operations is the Canadian dollar and the functional currency for the Company’s U.S. operations is the U.S. dollar. Therefore, gains and losses on U.S. dollar denominated transactions and the effect of translating U.S. dollar denominated balances of Canadian operations are recorded in net loss. The effects of translating the Company’s Canadian operations from the Canadian dollar to the U.S. dollar are recorded in Other comprehensive income (loss).
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and cash equivalents Cash and cash equivalents consists of cash balances and highly liquid investments with original maturities of three months or less that are considered to be cash equivalents. Cash equivalents are held for the purpose of meeting short-term cash commitments rather than for investment or other purposes. Restricted cash is excluded from cash and cash equivalents and is included in other long-term assets.
Term Deposits, Policy [Policy Text Block]	Term deposits The Company’s term deposits are classified as held to maturity and recorded at cost. Term deposits are held at Chartered Canadian banks with original maturities of 12 months or less. The term deposits are not traded in an active market.
Equity Method Investments [Policy Text Block]	Investment in affiliates Investments in unconsolidated ventures over which the Company has the ability to exercise significant influence, but does not control, are accounted for under the equity method and include the Company’s investments in the Donlin Gold and Galore Creek projects. The Company identified Donlin Gold LLC and Galore Creek Partnership as Variable Interest Entities (VIEs) as these entities are dependent on funding from their owners. All funding, ownership, voting rights and power to exercise control is shared equally on a 50/50 basis between the owners of each VIE. Therefore, the Company has determined that it is not the primary beneficiary of either VIE. The Company’s maximum exposure to loss is its equity investments in Donlin Gold LLC and Galore Creek Partnership, and amounts receivable from Galore Creek Partnership. The equity method is a basis of accounting for investments whereby the investment is initially recorded at cost and the carrying value is adjusted thereafter to include the investor’s pro rata share of post-acquisition earnings or losses of the investee, as computed by the consolidation method. Cash funding increases the carrying value of the investment. Profit distributions received or receivable from an investee reduce the carrying value of the investment. Donlin Gold LLC and Galore Creek Partnership are non-publicly traded equity investees owning exploration and development projects. Therefore, the Company assesses whether there has been a potential impairment triggering event for other-than-temporary impairment by testing the underlying assets of the equity investee for recoverability and assessing whether there has been a change in the development plan or strategy for the project. If the underlying assets are not recoverable, the Company will record an impairment charge equal to the difference between the carrying amount of the investee and its fair value.
Mineral Properties, Policy [Policy Text Block]	Mineral properties Mineral property expenditures are expensed as incurred except for expenditures associated with the acquisition of mineral property assets through a business combination or asset acquisition. The Company reviews and evaluates its mineral properties for impairment when events or changes in circumstances indicate that the related carrying amounts may not be recoverable. An impairment is considered to exist if the total estimated future cash flows on an undiscounted basis are less than the carrying amount of the assets. An impairment loss is measured and recorded based on the estimated fair value which may be determined using a discounted cash flow model.
Income Tax, Policy [Policy Text Block]	Income taxes The Company accounts for income taxes using the liability method, recognizing certain temporary differences between the financial reporting basis of the Company’s liabilities and assets and the related income tax basis for such liabilities and assets. This method generates deferred income tax liabilities and assets for the Company, as measured by the statutory tax rates in effect. The Company derives its deferred income tax charge or benefit by recording the change in deferred income tax liabilities and asset balances for the year. The Company’s deferred income tax assets include certain future tax benefits. The Company records a valuation allowance against any portion of those deferred income tax assets when it believes, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred income tax asset will not be realized.
Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]	Share-based payments The Company records share-based compensation awards exchanged for employee services at fair value on the date of the grant and expenses the awards in the consolidated statement of loss over the requisite employee service period. The fair values of stock options are determined using a Black-Scholes option pricing model. The fair values of PSUs are determined using a Monte Carlo valuation model. The Company's estimates may be impacted by certain variables including, but not limited to, stock price volatility, employee stock option exercise behaviors, additional stock option grants, estimates of forfeitures, the Company's performance and the Company’s performance in relation to its peers.
Earnings Per Share, Policy [Policy Text Block]	Net income (loss) per common share Basic and diluted income (loss) per share are presented for Net income (loss). Basic income (loss) per share is computed by dividing Net income (loss) by the weighted-average number of outstanding common shares for the period. Diluted income per share reflects the potential dilution that could occur if securities or other contracts that may require the issuance of common shares in the future were converted. Diluted income per share is computed by increasing the weighted-average number of outstanding common shares to include the additional common shares that would be outstanding after conversion and adjusting net income for changes that would result from the conversion. Only those securities or other contracts that result in a reduction in earnings per share are included in the calculation.
Reclassification, Policy [Policy Text Block]	Reclassifications The Company adopted Accounting Standard Update (ASU) No. 2016 - 09, which requires the classification of withholding tax on share-based compensation as a financing activity on the consolidated statement of cash flows. Refer to Recently adopted accounting pronouncements for further details.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently adopted accounting pronouncements Compensation—Stock Compensation In March 2016, ASU No. 2016 - 09 was issued related to stock-based compensation. The new guidance simplifies the accounting for stock-based compensation transactions, including income tax consequences, classification of awards as either equity or liabilities, classification of cash payments related to tax withholdings on behalf of employees on the consolidated statements of cash flows, and accounting for forfeitures. This update is effective in fiscal years, including interim periods, beginning after December 15, 2016. The Company adopted this guidance as of December 1, 2016, and reclassified $( 4,275 ) and $( 827 ) from Net cash used in operating activities to Net cash used in financing activities for the years ended November 30, 2016 and 2015, respectively. Accordingly the statements of cash flows for these years have been denoted as ‘revised.’ Adoption of this guidance had no other impact on the consolidated financial statements or disclosures. Recently issued accounting pronouncements Compensation—Stock Compensation In May 2017, ASU No. 2017 - 09 was issued to provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. The amendments will be applied prospectively to an award modified on or after the adoption date. The Company adopted this new guidance effective December 1, 2017, and does not expect it to have a material impact on the consolidated financial statements or disclosures. Restricted Cash In November 2016, ASU No. 2016 - 18 was issued related to the inclusion of restricted cash in the statement of cash flows. This new guidance requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents and restricted cash. This update is effective in fiscal years, including interim periods, beginning after December 15, 2017 and early adoption is permitted. The adoption of this guidance will result in the inclusion of the restricted cash balances within the overall cash balance and removal of the changes in restricted cash activity. Furthermore, the Company will be required to reconcile cash and cash equivalents and restricted cash reported within the consolidated balance sheets to the total shown in the consolidated statements of cash flows. The Company anticipates adopting this new guidance effective December 1, 2018, and does not expect it to have a material impact on the consolidated financial statements or disclosures. Classification of Certain Cash Receipts and Cash Payments In August 2016, ASU No. 2016 - 15 was issued related to the statement of cash flows. The new guidance will require the Company to make an accounting policy election to classify distributions received from equity method investees (Donlin Gold LLC and Galore Creek Partnership) using a cumulative earnings approach or a nature of the distribution approach. The election will affect the classification of future distributions on the statement of cash flows as cash inflows from operating activities or investing activities. The new guidance is effective for the Company’s fiscal year and interim periods beginning December 1, 2018, and early adoption is permitted. The Company has evaluated this guidance and does not expect it to have a material impact on the consolidated financial statements or disclosures. The Company anticipates retrospectively adopting the new guidance effective December 1, 2018. Leases In February 2016, ASU No. 2016 - 02 was issued related to leases, which was further amended in September 2017 by ASU No. 2017 - 13. The new guidance amends the recognition of lease assets and lease liabilities by lessees for those leases classified as operating leases and amends disclosure requirements associated with leasing arrangements. The new guidance is effective for the Company’s fiscal year beginning December 1, 2019. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. Adpoption of this guidance is not expected to materially increase the assets and liabilities of the Company. Classification and Measurement of Financial Instruments In January 2016, ASU No. 2016 - 01 was issued to amend the guidance on the classification and measurement of financial instruments. The new guidance requires entities to measure equity investments that do not result in consolidation and are not accounted for under the equity method at fair value and recognize any changes in fair value in net income. The new guidance also amends certain disclosure requirements associated with the fair value of financial instruments. The new guidance is effective for the Company’s fiscal year beginning December 1, 2018. Early adoption is not permitted. The Company expects the updated guidance to result in a reclassification of unrealized gains and losses on equity investments from accumulated other comprehensive income (loss) to accumulated deficit in the consolidated balance sheets upon adoption.