Description of Business and Summary of Significant Accounting Policies Description of Business and Summary of Significant Accounting Policies (Recent Accounting Pronouncements) (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 Liabilities	$ 346.0
Operating Lease Assets	$ 333.1		$ 0.0
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease Liabilities		$ 358.1
Operating Lease Assets		$ 344.6