Consolidated Statements of Changes in Equity (Parentheticals) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Treasury Stock repurchased, shares	61,920	71,506	34,759
Class A Common Stock [Member]
Stock issued for stock compensation, shares	348,818	458,565	266,542
Common Stock [Member] | Class A Common Stock [Member]
Settlement of deferred stock awards, shares	17,661	78,088
Stock Issued During Period, Shares, New Issues	4,000,000
Stock issued during period, shares	238,201
Common Stock [Member] | Class A Common Stock [Member] | Conversion of Class B Common Stock to Class A Common Stock [Member]
Conversion of shares to Class A Common Stock, shares	57,000	35,000	227,347
Common Stock [Member] | Class A Common Stock [Member] | Common stock and TEUs [Member]
Conversion of shares to Class A Common Stock, shares			3,539,240