Commitments and Contingencies Available Lines of Credit, Outstanding Standby Letter of Credits, and Bonds (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit		$ 500,000
Line of Credit Facility, Remaining capacity to support letters of credit	[1]	253,426
Credit Facility [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit	[1]	500,000	$ 660,000
Long-term borrowings	[1]	(151,837)	(91,469)
Standby LOCs issued and outstanding	[1]	(46,574)	(50,399)
Net available for additional borrowings and LOCs	[1]		449,601
Unsecured Multicurrency Revolving Lines of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit		97,989	106,855
Standby LOCs issued and outstanding		(31,122)	(28,636)
Short-term borrowings(2)	[2]	(3,884)	(4,282)
Net available for additional borrowings and LOCs		62,983	73,937
Surety Bond [Member]
Line of Credit Facility [Line Items]
Unsecured surety bonds in force		87,558	116,306
Line of Credit [Member]
Line of Credit Facility [Line Items]
Long-term borrowings		(151,837)	(91,469)
Net available for additional borrowings and LOCs	[1]	$ 301,589	$ 518,132

[1] Refer to Note 7 for details regarding our secured credit facilities.

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