New Accounting Pronouncements New Accounting Pronouncements - Leases (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 154.5
Operating Lease, Liability	166.1
Retained earnings	7,617.0		$ 7,692.9
Current finance lease liabilities	34.5
Non-current finance lease liabilities	$ 60.0
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 154.0
Operating Lease, Liability		164.0
Retained earnings		32.0
Current finance lease liabilities		3.0
Non-current finance lease liabilities		$ 82.0