Pre-tax Amounts Recorded in AOCI (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	$ (230.6)	$ (237.4)
Net prior service credit	(1.2)	(0.1)
Total amounts recorded	(231.8)	(237.5)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net actuarial gain (loss)	31.3	(13.5)
Net prior service credit	6.2	7.2
Total amounts recorded	$ 37.5	$ (6.3)