CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Treasury stock, common shares (shares)	352,161	352,161
Common Stock
Common stock, par value (USD per share)	$ 1	$ 1	$ 1
Common stock, shares authorized (shares)	50,000,000	50,000,000
Common stock, shares issued (shares)	23,783,440	22,643,255
Common stock, shares outstanding (shares)	23,431,279	22,291,094
Class B Common Stock
Common stock, par value (USD per share)	$ 1	$ 1	$ 1
Common stock, shares authorized (shares)	0	1,500,000
Common stock, shares issued (shares)	0	1,050,012
Common stock, shares outstanding (shares)	0	1,050,012