Unaudited Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Common Class A
Common stock, par value	$ 1	$ 1
Common stock, shares outstanding	6,756,482	6,770,689
Common Class B
Common stock, par value	$ 1	$ 1
Common stock, convertible conversion ratio	1	1
Common stock, shares outstanding	1,582,155	1,582,310