Commitments and Contingencies Available Lines of Credit, Outstanding Standby Letter of Credits, and Bonds (Details) - USD ($) $ in Thousands		Jan. 05, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 23, 2015
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit		$ 500,000			$ 500,000
Credit Facility [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit	[1]		$ 500,000	$ 500,000
Long-term borrowings	[1]		(125,414)	(97,167)
Standby LOCs issued and outstanding	[1]		(31,881)	(46,103)
Net available for additional borrowings and LOCs	[1]		218,119	203,897
Unsecured Multicurrency Revolving Lines of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit			110,477	91,809
Standby LOCs issued and outstanding			(21,030)	(21,734)
Short-term borrowings(2)	[2]		(916)	(69)
Net available for additional borrowings and LOCs			88,531	70,006
Surety Bond [Member]
Line of Credit Facility [Line Items]
Unsecured surety bonds in force			51,344	48,221
Line of Credit [Member]
Line of Credit Facility [Line Items]
Long-term borrowings			(125,414)	(97,167)
Net available for additional borrowings and LOCs	[1]		$ 342,705	$ 356,730

[1] Refer to Note 6 and Note 19 for details regarding our secured credit facilities, including the refinancing of the 2015 credit facility.

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