Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 0.8	$ 0.9
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Common Stock, Shares Authorized	200,000,000	200,000,000
Common Stock, Shares, Issued	129,665,899	153,348,542
Common Stock, Shares, Outstanding	111,945,021	136,933,191
Preferred Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Preferred Stock, Shares Authorized	15,000,000	15,000,000
Preferred Stock, Shares Issued	0	0
Treasury Stock, Shares	17,720,878	16,525,351