Schedule I - Financial Information of the Registrant (Parent Company) - Balance Sheets (Additional Information) (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value (in usd per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	51,500,000	51,500,000
Common stock, shares issued (in shares)	24,061,568	24,071,508
Common stock, shares outstanding (in shares)	23,709,407	23,719,347
Treasury stock, common shares (in shares)	352,161	352,161
Parent Company
Condensed Balance Sheet Statements, Captions [Line Items]
Common stock, par value (in usd per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	51,500,000	51,500,000
Common stock, shares issued (in shares)	24,061,568	24,071,508
Common stock, shares outstanding (in shares)	23,709,407	23,719,347
Treasury stock, common shares (in shares)	352,161	352,161