Retirement Benefits (Details 6) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	$ 5.4	$ 4.8
Current liabilities	(5.5)	(5.1)
Noncurrent liabilities	(673.6)	(731.5)
Total amount recognized	(673.7)	(731.8)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	0.0	0.0
Current liabilities	(30.9)	(32.7)
Noncurrent liabilities	(326.7)	(312.5)
Total amount recognized	$ (357.6)	$ (345.2)