Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Details Textual)

v3.19.1
Stockholders' Equity (Details Textual)
 1 Months Ended 12 Months Ended
Apr. 23, 2019
$ / shares
Feb. 28, 2019
class_of_stock
$ / shares
Feb. 28, 2018
$ / shares
Feb. 28, 2017
$ / shares
Class of Stock [Line Items]        
Number of classes of common stock with a material number of shares outstanding | class_of_stock   2    
Class B Convertible Common Stock [Member]        
Class of Stock [Line Items]        
Common stock, conversion features   convertible into shares of Class A Common Stock on a one-to-one basis    
Common stock, voting rights   ten votes per share    
Cash dividends declared per common share   $ 2.68 $ 1.88 $ 1.44
Class B Convertible Common Stock [Member] | Subsequent Event [Member]        
Class of Stock [Line Items]        
Cash dividends declared per common share $ 0.68      
Class A Common Stock [Member]        
Class of Stock [Line Items]        
Common stock, voting rights   one vote per share    
Common stock, dividend rights   10.00%    
Cash dividends declared per common share   $ 2.96 $ 2.08 $ 1.60
Class A Common Stock [Member] | Subsequent Event [Member]        
Class of Stock [Line Items]        
Cash dividends declared per common share 0.75      
Class 1 Common Stock [Member]        
Class of Stock [Line Items]        
Common stock, conversion features   convertible into shares of Class A Common Stock on a one-to-one basis    
Common stock, voting rights   generally have no voting rights    
Class 1 Common Stock [Member] | Subsequent Event [Member]        
Class of Stock [Line Items]        
Cash dividends declared per common share $ 0.68