Overview, Basis of Presentation and Recently Issued Authoritative Accounting Guidance (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets	$ 30.4
Lease liability	30.9
Retained earnings	641.3		$ 603.3
Pension and Other Postretirement Plans
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of new accounting standard	$ (11.5)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets		$ 30.0
Lease liability		$ 30.0