Other Consolidated Balance Sheet Accounts Detail (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of year	$ 9.4	$ 10.9	$ 9.6
Net additions charged to operations	2.2	1.1	2.0
Less: Write-offs and adjustments	(0.8)	(2.6)	(0.7)
Balance, end of year	10.8	9.4	10.9
Other Receivables, Net, Current [Abstract]
Vendor receivables, net	46.0	46.0
Insurance recoverables, current	1.4	5.3
Other	14.1	7.7
Total other receivables, net	61.5	59.0
Deposits and Prepayments [Abstract]
Deposits	4.3	4.9
Prepaid taxes	4.1	4.3
Vendor prepayments	20.7	26.4
Racking allowances, current	6.4	7.9
Other prepayments	8.2	9.5
Total deposits and prepayments	43.7	53.0
Other Assets, Noncurrent [Abstract]
Insurance recoverables	16.6	17.2
Debt issuance costs	0.8	1.1
Insurance deposits	4.0	3.7
Racking allowances, net	5.5	4.9
Other assets	4.2	6.2
Total other non-current assets, net	31.1	33.1
Accrued Liabilities, Current [Abstract]
Accrued payroll, retirement and other benefits	32.5	25.8
Claims liabilities, current	10.4	12.9
Accrued customer incentives payable	18.2	18.5
Indirect taxes	7.2	5.9
Vendor advances	5.1	5.3
Other accrued expenses	20.0	19.7
Total accrued liabilities	$ 93.4	$ 88.1