Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 1.0	$ 1.0
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	153,147,190	152,979,708
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	9,041,733	9,995,456