Operations and Significant Accounting Policies - Accounts Receivable (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Apr. 03, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade accounts receivable	$ 86.8	$ 77.1
European Roll Coated Aluminum | U.K.
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, direct write off	$ 1.2