Related Party Transactions (Details) - Director [Member] - Methvin Company [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party	$ 4.6	$ 4.3	$ 8.4	$ 8.4
Accounts Receivable, Related Parties, Current	$ 2.0		$ 2.0		$ 1.6