Unaudited Condensed Consolidated Balance Sheets (Parenthetical)	Sep. 30, 2016 $ / shares shares	Dec. 31, 2015 $ / shares shares	Sep. 30, 2015 $ / shares shares
Shares Outstanding Class A
Common stock, par value (in dollars per share) | $ / shares	$ 1	$ 1	$ 1
Common stock, shares outstanding (in shares) | shares	5,205,293	5,265,446	5,276,963
Shares Outstanding Class B
Common stock, par value (in dollars per share) | $ / shares	$ 1	$ 1	$ 1
Common stock, convertible conversion ratio	1	1	1
Common stock, shares outstanding (in shares) | shares	1,571,215	1,571,727	1,572,027