Note 9 - Redeemable, Convertible Preferred Stock (Details Textual) - USD ($)					1 Months Ended	3 Months Ended				12 Months Ended
	Mar. 30, 2021	Feb. 26, 2021	Feb. 25, 2021	Nov. 15, 2016	Jul. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Temporary Equity [Line Items]
Net proceeds from Series A Preferred Stock										$ 99,000,000
Payments for repurchase of preferred stock										$ 100,000,000
Preferred stock, No Par Value										$ 0	$ 0	$ 0
Series A Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Net proceeds from Series A Preferred Stock				$ 198,000,000
Series A Redeemable Preferred Stock [Member] | Purchase Agreement [Member]
Temporary Equity [Line Items]
Preferred stock, number of shares issued				2,000,000
Percentage of cash dividend payable on preferred stock				5.50%
Gross proceeds from issuance of shares				$ 200,000,000
Preferred stock, liquidation preference per share				$ 100
Purchase agreement date				Nov. 07, 2016
Series A Preferred Stock [Member]
Temporary Equity [Line Items]
Percentage of cash dividend payable on preferred stock				5.50%
Preferred stock, redemption price per share				$ 100
Stock repurchased		1,000,000
Common stock price equal or exceeds preferred stock conversion price percentage				125.00%
Preferred stock conversion description				The Company had the right to convert Series A Preferred Stock into Common Stock at any time after the second anniversary of the initial issuance if the closing price of the Common Stock equaled or exceeded 125 percent of the then-effective conversion price for 45 trading days within a period of 60 consecutive trading days, with the last trading day of such 60 day period ending on the trading day immediately preceding the business day on which the Company issues a press release announcing the mandatory conversion.
Net proceeds received to derivative liability				$ 43,000,000
Carrying value of preferred stock at issuance				155,000,000
Gross proceeds from preferred stock				200,000,000
Fair value of derivative liability				43,000,000
Transaction costs				$ 2,000,000
Preferred stock, redemption date				Nov. 15, 2021
Preferred stock prior to extinguishment carrying value including fair value of embedded derivative liability		$ 203,000,000
Temporary equity deemed preferred stock dividends		$ 8,000,000
Dividends					$ 11,000,000	$ 0	$ 0	$ 0	$ 0
Series A Preferred Stock [Member] | Purchase Agreement [Member]
Temporary Equity [Line Items]
Initial conversion rate of preferred stock to common stock				5.7471
Initial conversion price of preferred stock per share of common stock				$ 17.40
Series A Preferred Stock [Member] | Repurchase and Exchange Agreement [Member]
Temporary Equity [Line Items]
Stock repurchased		1,000,000
Payments for repurchase of preferred stock		$ 100,641,667
Stock exchanged during period shares		1,000,000
Dividends paid		$ 641,667
Series B Preferred Stock [Member]
Temporary Equity [Line Items]
Percentage of cash dividend payable on preferred stock			4.00%
Preferred stock, liquidation preference per share			$ 100
Preferred stock, redemption price per share										$ 100
Preferred stock conversion description										The Company will have the right to cause the mandatory conversion of the Series B Preferred Stock into shares of Common Stock at any time after the initial issuance of the Series B Preferred Stock if the closing price of the Common Stock has equaled or exceeded $14.50 (subject to adjustment in the same manner as the conversion price) for 45 trading days within a period of 60 consecutive trading days.
Carrying value of preferred stock at issuance		93,000,000
Fair value of derivative liability		1,000,000
Transaction costs		$ 1,000,000
Preferred stock, redemption date		May 28, 2026
Temporary equity fair value of preferred stock at the time of issuance		$ 95,000,000
Common stock price equal or exceeds preferred stock conversion price		$ 14.50
Fair value allocated to derivative liability										$ 1,000,000
Series B Preferred Stock [Member] | Other Long-Term Liabilities [Member]
Temporary Equity [Line Items]
Fair value of derivative liability										$ 1,000,000
Series B Preferred Stock [Member] | Purchase Agreement [Member]
Temporary Equity [Line Items]
Initial conversion rate of preferred stock to common stock		9.5238
Initial conversion price of preferred stock per share of common stock		$ 10.50
Series B Preferred Stock [Member] | Repurchase and Exchange Agreement [Member]
Temporary Equity [Line Items]
Percentage of cash dividend payable on preferred stock		4.00%
Preferred stock, number of shares issued		1,000,000
Preferred stock, No Par Value
Temporary equity exchange basis		one-for-one
Series C Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock, redemption price per share			100
Preferred stock conversion description										The Company will have the right to cause the mandatory conversion of the Series C Preferred Stock into shares of Common Stock (i) at any time after February 26, 2023 if the closing price of the Common Stock has equaled or exceeded 200% of the then-effective conversion price for 45 trading days within a period of 60 consecutive trading days, or (ii) at any time after February 26, 2024 if the closing price of the Common Stock has equaled or exceeded 150% of the then-effective conversion price for 45 trading days within a period of 60 consecutive trading days.
Net proceeds received to derivative liability		$ 2,000,000
Carrying value of preferred stock at issuance		97,000,000
Fair value of derivative liability		2,000,000
Transaction costs		$ 1,000,000
Preferred Stock Right To Extend Redemption Date Term		2 years
Series C Preferred Stock [Member] | After February 26, 2023 [Member]
Temporary Equity [Line Items]
Common stock price equal or exceeds preferred stock conversion price percentage										200.00%
Series C Preferred Stock [Member] | After February 26, 2024 [Member]
Temporary Equity [Line Items]
Common stock price equal or exceeds preferred stock conversion price percentage										150.00%
Series C Preferred Stock [Member] | Other Long-Term Liabilities [Member]
Temporary Equity [Line Items]
Fair value of derivative liability										$ 2,000,000
Series C Preferred Stock [Member] | Purchase Agreement [Member]
Temporary Equity [Line Items]
Preferred stock, number of shares issued	250,000	750,000
Preferred stock, liquidation preference per share			100
Purchase agreement date		Feb. 26, 2021
Preferred stock, No Par Value
Initial conversion price of preferred stock per share of common stock			$ 10
Gross proceeds from preferred stock	$ 25,000,000	$ 75,000,000
Preferred stock, redemption date			May 28, 2026
Preferred stock, number of shares issued		1,000,000
Gross proceeds owed on issuance of preferred stock		$ 100,000,000
Percentage of in-kind dividend payable on preferred stock			5.00%
Series C Preferred Stock [Member] | Dividend and Other Rights [Member]
Temporary Equity [Line Items]
Percentage of in-kind dividend payable on preferred stock			5.00%
Preferred stock, liquidation preference			$ 100