v3.21.2
FINANCIAL INSTRUMENTS - Assets and liabilities carried at fair value measured on a recurring basis (Details) - USD ($)
$ in Thousands
Sep. 30, 2021
Dec. 31, 2020
Recurring    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Mutual funds $ 26,220 $ 26,850
Corporate bonds 649,536 611,184
Marketable securities 254 253
Derivative instruments - Assets 1,890 353
Total assets measured at fair value 677,900 638,640
Derivative instruments - Liability 847 1,505
Total liabilities measured at fair value 847 1,505
Recurring | Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Mutual funds 26,220 26,850
Marketable securities 254 253
Total assets measured at fair value 26,474 27,103
Recurring | Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Corporate bonds 649,536 611,184
Derivative instruments - Assets 1,890 353
Total assets measured at fair value 651,426 611,537
Derivative instruments - Liability 847 1,505
Total liabilities measured at fair value 847 1,505
Fair Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Marketable securities 254 253
Derivative instruments - Assets 1,890 353
Derivative instruments - Liability $ 847 $ 1,505