Note 20 - Incentive Plans (Details Textual) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement, Expense		$ 20.2	$ 18.2	$ 21.6
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total		$ 33.8
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition		2 years 9 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		1.1
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		0	0	0
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit		$ 13.05	$ 24.12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term		2 years 1 month 6 days
Proceeds from Stock Options Exercised		$ 3.9	$ 0.6	$ 1.5
Common Stock, Shares, Issued, Total		431,814,951	421,388,879
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		5.00%
Defined Contribution Plan, Cost		$ 2.2	$ 2.2	2.1
Employee [Member]
Severance Costs		$ 2.6	$ 3.8	$ 5.5
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 18.03	$ 14.72	$ 25.04
Dividend, Share-based Payment Arrangement, Shares		$ 3.0	$ 2.8	$ 2.4
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 22.00	$ 15.40	$ 23.35
Common Stock, Shares, Issued, Total		104,551	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	[1]	0.00%	0.00%	0.00%

[1] Total Shareholder Returns, as used in the performance share awards computation, are measured based on cumulative dividend stock prices, as such a zero percent dividend yield is utilized.