New Accounting Pronouncements (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Jan. 01, 2019
Retained Earnings | Accounting Standards Update 2018-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassifications due to adoption of accounting standard		$ 6.5
Other Nonoperating Income (Expense) | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassifications due to adoption of accounting standard	$ (0.6)	$ (1.8)
Forecast | Accounting Standards Update 2018-11
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets			$ 50.0
Lease liabilities			$ 60.0