Accounts Receivable, Net of Allowance (Schedule of Activity, Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Rollforward]
Allowance for doubtful accounts at beginning of year	$ 15.7	$ 11.3
Provision for doubtful accounts	1.8	6.1
Amounts charged against the allowance	(3.6)	(1.7)
Allowance for doubtful accounts at end of year	$ 13.9	$ 15.7