XML 77 R64.htm IDEA: XBRL DOCUMENT v3.7.0.1
Note 10 - Stock-based Compensation - Stock Option Valuation Assumptions (Details)
12 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2015
Risk-free interest rate 1.22%    
Expected option life (years) (Year) 5 years    
Dividend yield 0.55% 0.70% 0.90%
Minimum [Member]      
Volatility 32.05% 27.10% 24.40%
Risk-free interest rate   1.90%
Expected option life (years) (Year)   6 years
Maximum [Member]      
Volatility 33.76% 30.20% 27.10%
Risk-free interest rate   2.30%
Expected option life (years) (Year)   8 years