Unaudited Condensed Consolidated Balance Sheets (Parenthetical)	Jun. 30, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares	Jun. 30, 2016 $ / 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	5,266,268	5,207,955	5,240,777
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	1,570,448	1,570,915	1,571,518