Schedule II (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Trade Accounts Receivable [Member]
Valuation and Qualifying Accounts and Reserves [Line Items]
Balance at Beginning of Period	$ 1.1		$ 1.0		$ 0.9
Additions, Charged to Income	1.8		1.3		1.0
Additions, Other Charges	0		0		0
Deductions from Reserves	1.8	[1]	1.2	[1]	0.9	[1]
Balance at End of Period	1.1		1.1		1.0
Finance Receivables - Long-Term [Member]
Valuation and Qualifying Accounts and Reserves [Line Items]
Balance at Beginning of Period	0.6		0.6		0.6
Additions, Charged to Income	0		0		0
Additions, Other Charges	0		0		0
Deductions from Reserves	0	[1]	0	[1]	0	[1]
Balance at End of Period	0.6		0.6		0.6
Deferred Tax Assets [Member]
Valuation and Qualifying Accounts and Reserves [Line Items]
Balance at Beginning of Period	8.0		2.4		0.4
Additions, Charged to Income	14.1		5.6		2.0
Additions, Other Charges	0		0		0
Deductions from Reserves	0	[1]	0	[1]	0	[1]
Balance at End of Period	$ 22.1		$ 8.0		$ 2.4

[1] Includes uncollectible accounts written off.