All Identifiable Assets in each Geographic Area (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 5,106.4	[1]	$ 3,837.3	[1]	$ 3,418.0	[1]
Domestic
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	3,817.0		3,128.6
Foreign
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 1,289.4		$ 708.7

[1] Corporate assets (including cash and cash equivalents) of $599.4, $304.6 and $123.8 at December 31, 2012, 2011 and 2010, respectively, have been allocated to the above segments in a manner consistent with our corporate expense allocations. Prior year amounts have been restated to reflect this revised allocation methodology.