Debt (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	$ 389,040	$ 343,332
Borrowings under lines of credit and overdrafts	1,840	12,364
Total debt, net of unamortized discounts	385,841	346,052
Less current maturities	(2,380)	(12,904)
Long-term debt	383,461	333,148
Convertible Debt [Member] | 3.375% Convertible Notes [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	55,636	55,636
Debt Instrument, Fair Value Disclosure	60,615	59,038
Debt Instrument, Unamortized Discount	(4,250)	(5,333)
Convertible notes stated interest rate	3.375%
Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	331,400	281,900
Debt Instrument, Fair Value Disclosure	325,370	270,288
Line of credit facility, maximum borrowing capacity	500,000
Lines of Credit and Overdrafts [Member]
Debt Instrument [Line Items]
Debt Instrument, Fair Value Disclosure	1,840	12,364
Borrowings under lines of credit and overdrafts	1,840	12,364
Foreign Bank Borrowings [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	1,215	1,485
Debt Instrument, Fair Value Disclosure	1,215	1,642
Lines of Credit [Member]
Debt Instrument [Line Items]
Borrowings under lines of credit and overdrafts		12,000
Line of credit facility, maximum borrowing capacity	15,000
Line of Credit Facility, Interest Rate at Period End		2.17%
Repayment period	7 days
Bank Overdrafts [Member]
Debt Instrument [Line Items]
Borrowings under lines of credit and overdrafts	$ 1,840	$ 364
Repayment period	2 days
Minimum [Member] | Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument basis spread on LIBOR	1.10%
Maximum [Member] | Revolving Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument basis spread on LIBOR	1.70%