Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Condensed Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts	$ 6.9	$ 6.2
Common stock stated value per share	$ 20.00	$ 20.00
Authorized	50,000,000	50,000,000
Issued to voting trustees	19,211,186	18,665,064
Issued to shareholders	3,979,239	3,872,159
In treasury, at cost	(503,492)	(62,700)
Outstanding Common Stock	22,686,933	22,474,523