Employee Benefit Plans (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) pension_plan	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) pension_plan	Sep. 30, 2017 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Cost	$ 2.7	$ 2.0	$ 8.8	$ 7.4
Number Of Company Sponsored Union Pension Plans | pension_plan	2		2
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 31.7		$ 31.7
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 0.6		$ 0.6