Note 4 - Share-Based Compensation (Detail) - Stock Options Valuation Assumptions	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Minimum [Member]
Expected dividend yield at date of grant	2.63%	2.35%
Expected stock price volatility	29.10%	28.70%
Risk-free interest rate	0.56%	1.87%
Expected life of options (in years)	4 years	4 years
Maximum [Member]
Expected dividend yield at date of grant	3.98%	2.55%
Expected stock price volatility	31.70%	32.00%
Risk-free interest rate	1.15%	2.14%
Expected life of options (in years)	6 years	6 years