Note 9 - Debt, Credit Facility and Leases (Details Textual) $ in Thousands, $ in Millions					12 Months Ended
	Feb. 16, 2026	Jul. 21, 2022	Jul. 09, 2020 CAD ($)	Mar. 19, 2020 USD ($)	Feb. 15, 2026	Feb. 15, 2025	Dec. 31, 2024 USD ($)	Feb. 15, 2024	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021	May 03, 2024 USD ($)	Jul. 09, 2020 USD ($) Contract	Jul. 09, 2020 CAD ($) Contract	Feb. 19, 2020 USD ($)
Proceeds from issuance of long-term debt							$ 279,000		$ 239,000	$ 25,000
Finance lease liability							21,912		26,800
Finance lease liability, current							8,200		9,800
Finance lease liability, noncurrent							13,700		17,000
Finance lease right-of-use asset							14,000		20,300
Finance lease right-of-use asset, amortization							7,900		12,600	7,100
Finance lease, interest expense							900		$ 900	$ 900
Finance lease, liability, payment, due							24,135
Finance lease, liability, undiscounted excess amount							$ 2,223
Finance lease, weighted average remaining lease term (year)							1 year 8 months 12 days		2 years 2 months 12 days
Finance lease, weighted average discount rate, percent							9.70%		9.90%
Finance lease, liability, statement of financial position [Extensible Enumeration]										Finance lease liability	Finance lease liability
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]							Liabilities		Liabilities
Finance lease, right-of-use asset, statement of financial position [Extensible Enumeration]							Properties, plants, equipment and mine development, net		Properties, plants, equipment and mine development, net
Operating Lease, Liability, Statement of Financial Position [Extensible Enumeration]							Liabilities, Current		Liabilities, Current	Operating lease liability	Operating lease liability
Operating lease liability							$ 7,995		$ 8,600
Operating lease liability, current							900		800
Operating lease liability, noncurrent							7,100		7,800
Operating lease right-of-use asset							7,544		8,349
Operating lease expense							$ 3,800		$ 3,100	$ 3,100
Operating lease, weighted average remaining lease term (year)							7 years 3 months 18 days		9 years 9 months 18 days
Operating lease, weighted average discount rate, percent							5.70%		6.50%
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]							Liabilities, Current		Liabilities, Current
Operating lease, liability, statement of financial position [Extensible Enumeration]							Total current liabilities		Total current liabilities	Operating lease liability	Operating lease liability
New Credit Agreement [Member]
Line of credit facility, maximum borrowing capacity							$ 195,800
Long-term line of credit							6,200		$ 6,900
Proceeds from lines of credit							$ 23,000		128,000
New Credit Agreement [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of credit facility, maximum borrowing capacity												$ 150,000
Line of credit facility, commitment fee percentage		0.45%
New Credit Agreement [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Line of credit facility, maximum borrowing capacity												$ 225,000
Line of credit facility, commitment fee percentage		0.7875%
New Credit Agreement [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt instrument, basis spread on variable rate							2.00%
New Credit Agreement [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Debt instrument, basis spread on variable rate							3.50%
New Credit Agreement [Member] | Base Rate [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt instrument, basis spread on variable rate							1.00%
Debt instrument, basis spread on variable rate, applicable margin		1.00%
New Credit Agreement [Member] | Base Rate [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Debt instrument, basis spread on variable rate							2.50%
New Credit Agreement [Member] | Fed Funds Effective Rate Overnight Index Swap Rate [Member] | Revolving Credit Facility [Member]
Debt instrument, basis spread on variable rate		0.50%
New Credit Agreement [Member] | Leverage Ratio Applicable Margin [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Debt instrument, participation fee, percent		2.00%
New Credit Agreement [Member] | Leverage Ratio Applicable Margin [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Debt instrument, participation fee, percent		3.50%
Senior Notes [Member]
Long-term debt balance							$ 495,184		$ 636,000
Senior Notes [Member] | The 2028 Senior Notes [Member]
Debt instrument, interest rate, stated percentage							7.25%		7.25%						7.25%
Debt instrument, face amount															$ 475,000
Underwriting discount on senior notes															1.16%
Debt instrument, unamortized discount															$ 5,500
Debt instrument, redemption price, percentage								105.438%
Debt instrument, redemption price, percentage, net of cash proceeds of equity offerings											35.00%
Debt instrument, redemption price, percentage, including accrued and unpaid interest											101.00%
Long-term debt balance							$ 472,184		$ 471,270
Senior Notes [Member] | The 2028 Senior Notes [Member] | Forecast [Member]
Debt instrument, redemption price, percentage	100.00%				101.813%	103.625%
Senior Notes [Member] | The 2021 Senior Notes [Member]
Proceeds from issuance of long-term debt				$ 469,500
Previously outstanding				6.875%
Interest expense debt							$ 35,400		$ 34,400	$ 35,400
Senior Notes [Member] | IQ Notes [Member]
Debt instrument, interest rate, stated percentage							7.25%		7.25%				6.515%	6.515%
Debt instrument, face amount													$ 36,800	$ 50.0
Interest expense debt							$ 2,200		$ 2,300	$ 2,300
Debt instrument, unamortized premium, percentage of principal													103.65%	103.65%
Debt instrument, unamortized premium														$ 1.8
Debt instrument, effective annual yield													5.74%	5.74%
Long-term debt balance							0		$ 36,730					$ 48.2
Debt instrument, number of issuance installments | Contract													4	4
Proceeds from issuance of debt			$ 12.5
Payments of debt issuance costs			$ 0.6
Debt instrument, covenant, investment over next four years														$ 100.0
Senior Notes [Member] | New Credit Agreement [Member]
Letters of credit, drawn amount							$ 225,000