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Employee Benefit Plans and Other Postretirement Benefit Plans Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2016
Mar. 31, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Pension Plan, Liabilities, Noncurrent   $ 103.4 $ 103.1
Other Postretirement Defined Benefit Plan, Liabilities, Noncurrent   $ 545.7 $ 559.0
Scenario, Forecast [Member] | Other Postretirement Benefit Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plans, Estimated Future Employer Contributions in Current Fiscal Year $ 16.0