Note 1 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Schedule of Estimated Useful Lives of Assets

Depreciation and amortization are calculated principally on an accelerated or straight-line basis over the estimated useful lives of the assets, or the shorter of the estimated useful life or lease term for leasehold improvements, as follows:

Buildings	10 to 39 years
Furniture and equipment	3 to 15 years
Leasehold improvements	5 to 30 years

Assumptions Used in Option Pricing Model

Year ended December 31,	2017			2016			2015
Risk free interest rate		1.48	%		1.14	%		1.06	%
Dividend yield		3.19	%		3.78	%		3.86	%
Volatility		17.9	%		22.6	%		26.7	%
Expected life (years)		4.2			4.2			5.0