Segment information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Revenue and Operating Profit [Line Items]
Revenues	$ 977.4	$ 940.7
Operating profit	16.2	46.7
Capital expenditures	34.1	33.5
Depreciation and amortization	44.5	41.0
Total assets	2,651.0		2,553.9
Unconsolidated Equity Affiliates held by International Segment [Abstract]
Carrying value of investments at year end	91.1
International [Member]
Segment Revenue and Operating Profit [Line Items]
Revenues	741.8	704.3
Operating profit	35.6	65.2
North America [Member]
Segment Revenue and Operating Profit [Line Items]
Revenues	235.6	236.4
Operating profit	(2.4)	5.8
Segment operating profit [Member]
Segment Revenue and Operating Profit [Line Items]
Operating profit	33.2	71.0
Non Segment [Member]
Segment Revenue and Operating Profit [Line Items]
Operating profit	$ (17.0)	$ (24.3)

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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