Significant Accounting Policies - Allowance for Doubtful Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at Beginning of year	$ 1.6	$ 1.7	$ 1.4
Provision for bad debt	0.1	0.2	0.9
Write-offs and Other	(0.4)	(0.3)	(0.6)
Balance at End of Year	$ 1.3	$ 1.6	$ 1.7