All Identifiable Assets in Each Geographic Area (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 3,837.3	[1]	$ 3,418.0	[1]	$ 2,840.1	[1]
Domestic
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	3,128.6		2,705.7
Foreign
Segment Reporting, Asset Reconciling Item [Line Items]
Identifiable assets	$ 708.7		$ 712.3

[1] Corporate assets (including cash and cash equivalents) of $304.6, $123.8 and $144.6 at December 31, 2011, 2010 and 2009, respectively, have been allocated to the above segments based on each segment's respective percentage of total assets.