Note 17 - Stock-based Compensation - Options and SARS Outstanding (Details) shares in Thousands	Dec. 31, 2019 $ / shares shares
Number of SARs outstanding (in shares)	641
SARs exercisable (in shares)	439
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 25.06
Stock Options and Stock Appreciation Rights SARs Expiring in 2020 [Member]
Number of SARs outstanding (in shares)	3
SARs exercisable (in shares)	3
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 14.02
Stock Options and Stock Appreciation Rights SARs Expiring in 2021 [Member]
Number of SARs outstanding (in shares)	27
SARs exercisable (in shares)	27
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 15.88
Stock Options and Stock Appreciation Rights SARs Expiring in 2022 [Member]
Number of SARs outstanding (in shares)	108
SARs exercisable (in shares)	108
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 15.25
Stock Options and Stock Appreciation Rights SARs Expiring in 2023 [Member]
Number of SARs outstanding (in shares)	80
SARs exercisable (in shares)	80
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 15.26
Stock Options and Stock Appreciation Rights SARs Expiring in 2024 [Member]
Number of SARs outstanding (in shares)	73
SARs exercisable (in shares)	73
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 19.37
Stock Options and Stock Appreciation Rights SARs Expiring in 2025 [Member]
Number of SARs outstanding (in shares)	63
SARs exercisable (in shares)	49
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 23.00
Stock Options and Stock Appreciation Rights SARs Expiring in 2026 [Member]
Number of SARs outstanding (in shares)	88
SARs exercisable (in shares)	55
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 25.84
Stock Appreciation Rights SARs Expiring in 2027 [Member]
Number of SARs outstanding (in shares)	46
SARs exercisable (in shares)	21
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 40.00
Stock Appreciation Rights SARs Expiring in 2028 [Member]
Number of SARs outstanding (in shares)	100
SARs exercisable (in shares)	23
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 37.75
Stock Appreciation Rights SARs Expiring in 2029 [Member]
Number of SARs outstanding (in shares)	53
SARs exercisable (in shares)	0
Weighted average exercise price of SARs outstanding (in dollars per share) | $ / shares	$ 37.01