Note 1 - Summary of Signficant Interim Accounting Policies - Significant Assumptions for Share-based Compensation Awards (Details) - $ / shares		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stock Appreciation Rights (SARs) [Member]
Exercise price (in dollars per share)		$ 16.35	$ 18.66	$ 16.35	$ 18.66
Market price (in dollars per share)				$ 16.35	$ 18.66
Risk free interest rate	[1]			1.30%	1.50%
Expected award life (years)	[2]			5 years
Expected volatility	[3]			36.50%	34.90%
Expected dividend yield	[4]			2.00%	1.60%
Employee Stock Option [Member] | Minimum [Member]
Exercise price (in dollars per share)		16.35	16.78	$ 16.35	$ 16.78
Market price (in dollars per share)				$ 16.35	$ 16.78
Risk free interest rate	[1]			1.10%	1.50%
Expected award life (years)	[2]			5 years
Expected volatility	[3]			36.50%	34.90%
Expected dividend yield	[4]			1.80%	1.60%
Employee Stock Option [Member] | Maximum [Member]
Exercise price (in dollars per share)		18.55	18.66	$ 18.55	$ 18.66
Market price (in dollars per share)				$ 18.55	$ 18.66
Risk free interest rate	[1]			1.80%	2.10%
Expected award life (years)	[2]			10 years
Expected volatility	[3]			40.30%	39.00%
Expected dividend yield	[4]			2.10%	1.90%
Employee Stock Option [Member]
Exercise price (in dollars per share)		16.47	17.40	$ 16.47	$ 17.40
Market price (in dollars per share)		$ 16.47	$ 17.40
Risk free interest rate	[1]	1.10%	1.60%
Expected award life (years)	[2]	5 years
Expected volatility	[3]	37.10%	36.80%
Expected dividend yield	[4]	2.10%	1.90%

[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 three and nine-month periods ended September 30, 2016 and 2015, was based on historical prices of Superior's common stock 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.