Recent Accounting Pronouncements (Schedule of Prospective Adoption of New Accounting Pronouncements) (Details) - Accounting Standards Update 2018-02 $ in Millions	Dec. 31, 2017 USD ($)	[1]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0.0
Retained Deficit
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 9.5

[1] See Note 2, "Recent Accounting Pronouncements," for additional information.