Commitments and Contingencies Available Lines of Credit, Outstanding Standby Letter of Credits, and Bonds (Details) - USD ($) $ in Thousands		Jun. 13, 2016	Mar. 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, Capacity remaining to support letters of credit	[1]		$ 254,072	$ 253,426
Credit Facility [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit	[2]		500,000	500,000
Long-term Line of Credit	[2]		132,572	151,837
Letters of Credit Outstanding, Amount	[2]		45,928	46,574
Unsecured Multicurrency Revolving Lines of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit			100,424	97,989
Letters of Credit Outstanding, Amount			26,392	31,122
Short-term borrowings(2)	[3]		(1,373)	(3,884)
Line of Credit Facility, Remaining Borrowing Capacity			72,659	62,983
Surety Bond [Member]
Line of Credit Facility [Line Items]
Unsecured surety bonds in force			131,617	87,558
Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit			300,000
Line of Credit Facility, Remaining Borrowing Capacity			254,100
Line of Credit [Member]
Line of Credit Facility [Line Items]
Long-term Line of Credit			132,572	151,837
Line of Credit Facility, Remaining Borrowing Capacity	[2]		$ 321,500	$ 301,589
Subsequent Event [Member] | Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Multicurrency revolving line of credit		$ 250,000
Line of Credit Facility, Remaining Borrowing Capacity		$ 204,100

[1] Subsequent to March 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.