Long-Term Debt (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Debt Instrument [Line Items]
Long-term debt	$ 1,384,639	$ 1,105,628
Less: current portion	100,526	91,406
Total	1,284,113	1,014,222
Obligations under capital leases
Debt Instrument [Line Items]
Long-term debt	4,679	6,330
Line of Credit
Debt Instrument [Line Items]
Long-term debt	527,884	175,407
$215 million term loan
Debt Instrument [Line Items]
Long-term debt	0	80,969
$100 million Private Placement notes 5.64%, due in 2015
Debt Instrument [Line Items]
Long-term debt	100,000	100,000
$175 million Private Placement notes 3.89%, due in 2017
Debt Instrument [Line Items]
Long-term debt	175,000	175,000
$225 million Private Placement notes 4.47%, due in 2020
Debt Instrument [Line Items]
Long-term debt	225,000	225,000
Acquisition notes weighted average rate of 2.95% and weighted average maturity of 4.3 years
Debt Instrument [Line Items]
Long-term debt	240,138	251,489
Foreign bank debt weighted average rate 6.73% and Weighted average maturity of 2.2 years
Debt Instrument [Line Items]
Long-term debt	$ 111,938	$ 91,433