Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Total long-term debt	$ 3,852,019	$ 2,934,131
Current portion of long-term debt	677,345	711,096
Long-term debt	3,174,674	2,223,035
Term loan facilities | September 2015 Term Loan Agreement
Debt Instrument [Line Items]
Total long-term debt	1,250,000	0
Senior Notes | 1.875% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	763,946	844,315
Senior Notes | 3.00% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	249,756	249,694
Senior Notes | 4.15% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	423,706	423,561
Senior Notes | 4.50% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	348,443	348,129
Senior Notes | 5.10% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	0	324,997
Senior Notes | 5.45% Senior Notes
Debt Instrument [Line Items]
Total long-term debt	349,005	348,971
Commercial Paper
Debt Instrument [Line Items]
Total long-term debt	351,349	367,178
Fixed Rate Foreign Borrowings
Debt Instrument [Line Items]
Total long-term debt	995	1,958
Variable-rate foreign bank loans
Debt Instrument [Line Items]
Total long-term debt	77,452	25,139
Variable-rate domestic bank loans
Debt Instrument [Line Items]
Total long-term debt	20,479	0
Capital Lease Obligations
Debt Instrument [Line Items]
Total long-term debt	16,807	0
Other long-term debt
Debt Instrument [Line Items]
Total long-term debt	$ 81	$ 189