Unaudited Condensed Consolidated Balance Sheets (Parenthetical)	Mar. 31, 2018 $ / shares shares	Dec. 31, 2017 $ / shares shares
Shares Outstanding Class A
Common stock, par value (in dollars per share) | $ / shares	$ 1	$ 1
Common stock, shares outstanding (in shares) | shares	5,369,326	5,282,106
Shares Outstanding Class B
Common stock, par value (in dollars per share) | $ / shares	$ 1	$ 1
Common stock, convertible conversion ratio	1	1
Common stock, shares outstanding (in shares) | shares	1,569,746	1,570,146