Note 13 - Capital Stock Share Repurchase Program (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2019 $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) $ / shares shares	Nov. 01, 2019 USD ($)	Aug. 14, 2019 USD ($)	Mar. 20, 2019 USD ($)	Aug. 16, 2018 USD ($)
3Q18 Repurchase Program
Capital Stock [Line Items]
Stock Repurchase Program, Authorized Amount							$ 100.0
1Q19 Repurchase Program
Capital Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 150.0
Total of 3Q18 and 1Q19 Repurchase Programs
Capital Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 250.0
Stock Repurchased During Period, Shares | shares		2,241,568	11,258,574
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares		$ 23.43	$ 22.22
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 0.0	$ 0.0
Percent of Reduction in Shares Outstanding		0.053	0.053
3Q19 Repurchase Program
Capital Stock [Line Items]
Stock Repurchase Program, Authorized Amount					$ 200.0
Stock Repurchased During Period, Shares | shares		1,104,786
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares		$ 22.64
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 175.0	$ 175.0
Subsequent Event | 3Q19 Repurchase Program
Capital Stock [Line Items]
Stock Repurchased During Period, Shares | shares	1,090,875
Accelerated Share Repurchases, Final Price Paid Per Share | $ / shares	$ 22.93
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 150.0