Additions to Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Acquired Finite-Lived Intangible Assets [Line Items]
Amount	$ 36.4	$ 19.9
Customer Relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Amount	29.9	14.7
Weighted Average Amortization Period	6 years 1 month 6 days	13 years 10 months 24 days
Trade Names
Acquired Finite-Lived Intangible Assets [Line Items]
Amount	3.5	1.1
Weighted Average Amortization Period	1 year 8 months 12 days	3 years 6 months
Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Amount	$ 3.0	$ 4.1
Weighted Average Amortization Period	4 years 3 months 18 days	4 years 6 months