Note 12 - Share-based Compensation - Summary of Significant Assumptions for Share-based Compensation Awards (Details) - $ / shares		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Risk free interest rate
Expected award (Year)		5 years
Stock Appreciation Rights (SARs) [Member]
Exercise price
Exercise price (in dollars per share)		$ 16.35	$ 18.66	$ 7.36
Market price
Market price (in dollars per share)		$ 16.35	$ 18.66	$ 7.36
Risk free interest rate
Risk free interest rate	[1]	1.30%	1.50%	1.50%
Expected award (Year)	[2]	5 years
Expected volatility
Expected volatility	[3]	36.50%	34.90%	42.50%
Expected dividend yield
Exoected dividend yield	[4]	2.00%	1.60%	3.70%
Employee Stock Option [Member] | Minimum [Member]
Exercise price
Exercise price (in dollars per share)		$ 16.35	$ 16.78	$ 7.36
Market price
Market price (in dollars per share)		$ 16.35	$ 16.78	$ 7.36
Risk free interest rate
Risk free interest rate	[1]	1.10%	1.50%	1.50%
Expected award (Year)	[2]	5 years
Expected volatility
Expected volatility	[3]	36.50%	34.90%	37.30%
Expected dividend yield
Exoected dividend yield	[4]	1.80%	1.60%	2.90%
Employee Stock Option [Member] | Maximum [Member]
Exercise price
Exercise price (in dollars per share)		$ 18.55	$ 18.66	$ 10.38
Market price
Market price (in dollars per share)		$ 18.55	$ 18.66	$ 10.38
Risk free interest rate
Risk free interest rate	[1]	1.80%	2.10%	2.60%
Expected award (Year)	[2]	10 years
Expected volatility
Expected volatility	[3]	40.30%	39.00%	42.50%
Expected dividend yield
Exoected dividend yield	[4]	2.10%	1.90%	3.70%

[1] The risk-free interest rate is based on the yield of a U.S. treasury bond with a similar maturity as the expected life of the awards.

[2] The expected life in years for awards granted was based on the historical exercise patterns experienced by the Company when the award is made.

[3] The determination of expected stock price volatility for awards granted in each of the two years ended December 31, was based on historical Superior common stock prices over a period commensurate with the expected life.

[4] The dividend yield assumption is based on the history and expectation of the Company's dividend payouts.