Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total long-term debt	$ 3,590,105	$ 3,834,959
Current portion of long-term debt	484,754	677,345
Long-term debt	3,105,351	3,157,614
Term loan facilities | September 2015 Term Loan Agreement
Debt Instrument [Line Items]
Total long-term debt	916,657	1,247,167
Senior Notes | 1.875% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	774,688	759,151
Senior Notes | 3.00% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	248,385	248,274
Senior Notes | 4.15% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	420,775	420,654
Senior Notes | 4.50% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	347,168	347,018
Senior Notes | 5.45% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	345,571	345,532
Commercial Paper
Debt Instrument [Line Items]
Total long-term debt	478,140	351,349
Fixed Rate Foreign Borrowings
Debt Instrument [Line Items]
Total long-term debt	1,010	995
Variable-rate foreign bank loans
Debt Instrument [Line Items]
Total long-term debt	41,114	77,452
Variable-rate domestic bank loans
Debt Instrument [Line Items]
Total long-term debt	0	20,479
Capital Lease Obligations
Debt Instrument [Line Items]
Total long-term debt	16,583	16,807
Other long-term debt
Debt Instrument [Line Items]
Total long-term debt	$ 14	$ 81