Long-Term Debt (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Senior Credit Facility Due August 2012
Debt Instrument [Line Items]
Interest rate %	1.10%	1.10%
Long-term debt, Variable rate debt	Libor + 62.5 bps and base rate	Libor + 62.5 bps and base rate
Long-term debt borrowing capacity	$ 850.0	$ 850.0
Term Loan
Debt Instrument [Line Items]
Long-term debt, face amount	215.0	215.0
Private Placement Notes 5.64 Percent, Due In 2015
Debt Instrument [Line Items]
Long-term debt, face amount	100.0	100.0
Interest rate %	5.64%	5.64%
Private Placement Notes 3.89 Percent, due in 2017
Debt Instrument [Line Items]
Long-term debt, face amount	175.0	175.0
Interest rate %	3.89%	3.89%
Private Placement Notes 4.47 Percent, due in 2020
Debt Instrument [Line Items]
Long-term debt, face amount	$ 225.0	$ 225.0
Interest rate %	4.47%	4.47%
Acquisition Notes Weighted Average Rate of 3.2 Percent And Weighted Average Maturity Of 5.6 years
Debt Instrument [Line Items]
Debt, maturity years	5.6	5.6
Interest rate %	3.20%	3.20%
Foreign Bank Debt Weighted Average Rate 6.9 Percent and Weighted Average Maturity of 2.5 Years
Debt Instrument [Line Items]
Debt, maturity years	2.5	2.5
Interest rate %	6.90%	6.90%