Commitments and Contingencies Available Lines of Credit, Outstanding Standby Letter of Credits, and Bonds (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Jun. 23, 2015
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],[2]	$ 203,897
Credit Facility [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit	[2]	500,000	$ 500,000
Long-term borrowings	[2]	(97,167)	(151,837)
Standby LOCs issued and outstanding	[2]	(46,103)	(46,574)
Net available for additional borrowings and LOCs	[1],[2]		253,426
Unsecured Multicurrency Revolving Lines of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit		91,809	97,989
Standby LOCs issued and outstanding		(21,734)	(31,122)
Short-term borrowings(2)	[3]	(69)	(3,884)
Net available for additional borrowings and LOCs		70,006	62,983
Surety Bond [Member]
Line of Credit Facility [Line Items]
Unsecured surety bonds in force		48,221	87,558
Line of Credit [Member]
Line of Credit Facility [Line Items]
Long-term borrowings		(97,167)	(151,837)
Net available for additional borrowings and LOCs	[2]	$ 356,730	$ 301,589

[1] During the year ended December 31, 2016, as a result of entering into the first and second amendments to the 2015 credit facility, the maximum limit available for additional standby LOCs under sub-facility was reduced from $300 million to $250 million.

[2] Refer to Note 6 for details regarding our secured credit facilities.

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