Schedule II (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Trade Accounts Receivable [Member]
Valuation and Qualifying Accounts and Reserves [Roll Forward]
Balance at Beginning of Period		$ 0.9	$ 1.7	$ 2.1
Additions, Charged to Income		2.7	(0.1)	0.9
Additions, Other Charges		0.0	0.0	0.0
Deductions from Reserves	[1]	1.1	0.7	1.3
Balance at End of Period		2.5	0.9	1.7
Finance Receivables – Long-Term [Member]
Valuation and Qualifying Accounts and Reserves [Roll Forward]
Balance at Beginning of Period		0.0	0.0	0.0
Additions, Charged to Income		0.0	0.0	0.0
Additions, Other Charges		0.0	0.0	0.0
Deductions from Reserves	[1]	0.0	0.0	0.0
Balance at End of Period		0.0	0.0	0.0
Deferred Tax Assets [Member]
Valuation and Qualifying Accounts and Reserves [Roll Forward]
Balance at Beginning of Period		70.0	66.5	60.0
Additions, Charged to Income		(0.1)	3.5	6.5
Additions, Other Charges		0.0	0.0	0.0
Deductions from Reserves	[1]	0.0	0.0	0.0
Balance at End of Period		$ 69.9	$ 70.0	$ 66.5

[1] Includes uncollectible accounts written-off.