XML 63 R53.htm IDEA: XBRL DOCUMENT v3.7.0.1
Employee Benefit Plans and Other Postretirement Benefit Plans Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Mar. 31, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Pension Plan, Liabilities, Noncurrent   $ 111.0 $ 113.5
Other Postretirement Defined Benefit Plan, Liabilities, Noncurrent   $ 543.6 $ 542.6
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