Note 1 - Significant Assumptions for Share-based Compensation Awards (Details) - $ / shares		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock Appreciation Rights (SARs) [Member]
Exercise price (in dollars per share)		$ 18.66	$ 7.36	$ 18.66	$ 7.36
Market price (in dollars per share)				$ 18.66	$ 7.36
Risk free interest rate	[1]			1.50%	1.50%
Expected award life (years) (2)	[2]			5 years
Expected volatility	[3]			34.90%	42.50%
Expected dividend yield	[4]			1.60%	3.70%
Employee Stock Option [Member] | Minimum [Member]
Exercise price (in dollars per share)		16.78	7.36	$ 16.78	$ 7.36
Market price (in dollars per share)				$ 16.78	$ 7.36
Risk free interest rate	[1]			1.50%	1.50%
Expected award life (years) (2)	[2]			5 years
Expected volatility	[3]			34.90%	37.30%
Expected dividend yield	[4]			1.60%	2.90%
Employee Stock Option [Member] | Maximum [Member]
Exercise price (in dollars per share)		18.66	10.38	$ 18.66	$ 10.38
Market price (in dollars per share)				$ 18.66	$ 10.38
Risk free interest rate	[1]			2.10%	2.60%
Expected award life (years) (2)	[2]			10 years
Expected volatility	[3]			39.00%	42.50%
Expected dividend yield	[4]			1.90%	3.70%
Employee Stock Option [Member]
Exercise price (in dollars per share)		17.40	10.38	$ 17.40	$ 10.38
Market price (in dollars per share)		$ 17.40	$ 10.38
Risk free interest rate	[1]	1.60%	1.80%
Expected award life (years) (2)	[2]	5 years
Expected volatility	[3]	36.80%	37.40%
Expected dividend yield	[4]	1.90%	2.90%

[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 ending September 30, 2015 and 2014 was based on historical common stock prices for the Company 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.