Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowances, accounts and notes receivable	$ 0.0	$ 6.3
Accumulated depreciation	$ 824.3	$ 778.5
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued		0
Preferred stock, shares outstanding		0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	87,170,197	87,170,197
Treasury stock, shares	48,575,901	47,312,248