Consolidated Balance Sheets (Parenthetical) - USD ($) $ / shares in Millions, $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Allowances for accounts receivable	$ 19.1	$ 20.3
Preferred stock, no par value (Class I & Class II Preferred stock)	$ 0.0	$ 0.0
Preferred stock, shares issued (Class I & Class II Preferred stock)	0	0
Common stock, no par value	$ 0.0	$ 0.0
Company common stock shares authorized	200,000,000	200,000,000
Common stock, shares issued	98,375,135	98,375,135
Treasury shares	21,267,889	20,672,133
Preferred Class A [Member]
Preferred stock, shares authorized (Class I & Class II Preferred stock)	10,000,000	10,000,000
Preferred Class B [Member]
Preferred stock, shares authorized (Class I & Class II Preferred stock)	10,000,000	10,000,000