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FINANCIAL INSTRUMENTS - Available-for-Sale Debt Securities in a Continuous Unrealized Loss Position (Details) - USD ($)
$ in Millions
Mar. 31, 2023
Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]    
Unrealized losses less than 12 months, fair value $ 241.0 $ 1,510.4
Unrealized losses less than 12 months, gross unrealized losses (3.1) (49.1)
Unrealized losses more than 12 months, fair value 4,176.7 3,538.3
Unrealized losses more than 12 months, gross unrealized losses (147.0) (149.4)
Total unrealized losses, fair value 4,417.7 5,048.7
Total unrealized losses, gross unrealized losses (150.1) (198.5)
U.S. treasuries    
Debt Securities, Available-for-sale [Line Items]    
Unrealized losses less than 12 months, fair value 71.7 731.7
Unrealized losses less than 12 months, gross unrealized losses (0.8) (26.0)
Unrealized losses more than 12 months, fair value 2,137.6 1,886.9
Unrealized losses more than 12 months, gross unrealized losses (68.9) (70.6)
Total unrealized losses, fair value 2,209.3 2,618.6
Total unrealized losses, gross unrealized losses (69.7) (96.6)
Corporate debt securities    
Debt Securities, Available-for-sale [Line Items]    
Unrealized losses less than 12 months, fair value 159.6 631.4
Unrealized losses less than 12 months, gross unrealized losses (2.0) (17.6)
Unrealized losses more than 12 months, fair value 1,550.3 1,221.9
Unrealized losses more than 12 months, gross unrealized losses (58.3) (58.4)
Total unrealized losses, fair value 1,709.9 1,853.3
Total unrealized losses, gross unrealized losses (60.3) (76.0)
U.S. government agencies    
Debt Securities, Available-for-sale [Line Items]    
Unrealized losses less than 12 months, fair value 9.7 102.7
Unrealized losses less than 12 months, gross unrealized losses (0.3) (4.4)
Unrealized losses more than 12 months, fair value 375.4 324.6
Unrealized losses more than 12 months, gross unrealized losses (15.0) (15.5)
Total unrealized losses, fair value 385.1 427.3
Total unrealized losses, gross unrealized losses (15.3) (19.9)
Municipal securities    
Debt Securities, Available-for-sale [Line Items]    
Unrealized losses less than 12 months, fair value 0.0 44.6
Unrealized losses less than 12 months, gross unrealized losses 0.0 (1.1)
Unrealized losses more than 12 months, fair value 113.4 104.9
Unrealized losses more than 12 months, gross unrealized losses (4.8) (4.9)
Total unrealized losses, fair value 113.4 149.5
Total unrealized losses, gross unrealized losses $ (4.8) $ (6.0)