Unaudited Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Common Class A
Common stock, par value	$ 1	$ 1	$ 1
Common stock, shares outstanding	6,454,764	6,770,689	6,799,142
Common Class B
Common stock, par value	$ 1	$ 1	$ 1
Common stock, convertible conversion ratio	1	1	1
Common stock, shares outstanding	1,581,835	1,582,310	1,590,421