Consolidated Statements of Shareholders' Equity (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common Stock [Member] | Common Class A [Member]
Shares of treasury stock purchased (in shares)	163,268	65,131	11,445
Shares of common stock issued for the exercise of stock options (in shares)	43,983	140,595	155,253
Dividends declared per common share (in dollars per share)	$ 0.62	$ 0.06	$ 0.05
Issuance of restricted common shares, net of forfeitures (in shares)	73,168	50,038
Common Stock [Member] | Common Class B [Member]
Shares of treasury stock purchased (in shares)	4,239	4,317	1,908
Shares of common stock issued for the exercise of stock options (in shares)	7,330	23,432	31,876
Dividends declared per common share (in dollars per share)	$ 3.72	$ 0.36	$ 0.31
Issuance of restricted common shares, net of forfeitures (in shares)	12,194	8,340
Common Class A [Member]
Shares of common stock issued for the exercise of stock options (in shares)	43,983
Common Class B [Member]
Shares of common stock issued for the exercise of stock options (in shares)	7,330