Unaudited Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Common Class A
Common stock, par value	$ 1	$ 1	$ 1
Common stock, shares outstanding	6,356,996	6,770,689	6,803,999
Common Class B
Common stock, par value	$ 1	$ 1	$ 1
Common stock, convertible conversion ratio	1	1	1
Common stock, shares outstanding	1,581,406	1,582,310	1,590,311