Long-Term Debt (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
$1 billion revolver weighted average rate 1.74%, due in 2016
Debt Instrument [Line Items]
Interest rate %	1.74%	1.74%
Maximum borrowing capacity of line of credit facility	$ 1,000	$ 1,000
$100 million Private Placement notes 5.64%, due in 2015
Debt Instrument [Line Items]
Long-term debt, face amount	100.0	100.0
Interest rate %	5.64%	5.64%
$175 million Private Placement notes 3.89%, due in 2017
Debt Instrument [Line Items]
Long-term debt, face amount	175.0	175.0
Interest rate %	3.89%	3.89%
$225 million Private Placement notes 4.47%, 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 2.91% and weighted average maturity of 4.0 years
Debt Instrument [Line Items]
Debt, maturity period	4 years	4 years
Interest rate %	2.91%	2.91%
Foreign bank debt weighted average rate 6.9% and Weighted average maturity of 2.3 years
Debt Instrument [Line Items]
Debt, maturity period	2 years 110 days	2 years 110 days
Interest rate %	6.90%	6.90%