Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Consolidated Balance Sheets [Abstract]
Allowance for doubtful accounts	$ 9.1	$ 6.9
Common stock stated value per share	$ 20.00	$ 20.00
Authorized	50,000,000	50,000,000
Issued to voting trustees	18,956,496	18,755,472
Issued to shareholders	3,929,845	3,905,994
In treasury, at cost	(53,108)	(57,047)
Outstanding Common Stock	22,833,233	22,604,419
Common shares subscribed	1,056,109	1,052,817
Less subscripton receivable	(1,056,109)	(1,052,817)