Note 14 - Capital Stock - Share Repurchase Programs (Level 4) $ / shares in Units, $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018 $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Feb. 13, 2020 USD ($)	Aug. 14, 2019 USD ($)	Mar. 20, 2019 USD ($)	Aug. 16, 2018 USD ($)	Aug. 09, 2017 USD ($)
3Q19 Repurchase Program
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 200.0
Stock Repurchased During Period, Shares | shares			2,195,661
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares			$ 22.79
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 150.0
1Q20 Repurchase Program
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 275.0
Total of 3Q19 and 1Q20 Repurchase Programs
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 475.0
Stock Repurchased During Period, Shares | shares		11,036,248
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares		$ 20.51
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 198.9
3Q18 Repurchase Program
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount							$ 100.0
1Q19 Repurchase Program
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 150.0
Total of 3Q18 and 1Q19 Repurchase Programs
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 250.0
Stock Repurchased During Period, Shares | shares			11,258,574
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares			$ 22.22
Percent of Reduction in Shares Outstanding			0.053
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 0.0
3Q17 Repurchase Program
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount								$ 50.0
Stock Repurchased During Period, Shares | shares	3,022,856
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares	$ 16.56