Commitments and Contingencies Available Lines of Credit, Outstanding Standby Letter of Credits, and Bonds (Details) (USD $) In Thousands	Jun. 30, 2011		Dec. 31, 2010
Line of Credit Facility [Line Items]
Unsecured Surety Bonds In Force	$ 133,352		$ 120,109
Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of credit	315,000	[1]	240,000	[1]
Standby letters of credit issued and outstanding	(39,970)	[1]	(43,540)	[1]
Net available for additional borrowings and lines of credit	275,030	[1]	196,460	[1]
Unsecured Multicurrency Revolving Lines of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit	74,685		49,122
Standby letters of credit issued and outstanding	(32,329)		(21,784)
Short-term borrowings	(264)	[2]	(66)	[2]
Net available for additional borrowings and lines of credit	$ 42,092		$ 27,272

[1] See Note 6 for details regarding our credit facility, which is secured.

[2] Short-term borrowings are included in “Other current liabilities” on the Consolidated Balance Sheets.