Employee Benefit Plans and Other Postretirement Benefits - Schedule of Effects of One-Percentage Point Change in Assumed Health Care Cost Trends on Postretirement Benefits (Details) - Postretirement Plans $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Effect on postretirement benefit obligation, 1-Percentage Point Decrease	$ (0.6)
Effect on postretirement benefit obligation, 1-Percentage Point Increase	0.6
Effect on net postretirement benefit cost, 1-Percentage Point Increase	$ 0.1