Revenue from Contracts with Customers - Accounts Receivable Reserve for Doubtful Accounts (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance as of beginning of fiscal year	$ 6.0	$ 5.9
Expense to increase the reserve	0.3	0.7
Write-off of uncollectible accounts	(1.3)	(0.4)
Balance as of period end	$ 5.0	$ 6.2