Quarterly report pursuant to Section 13 or 15(d)

Short-term and Long-term Investments, Restricted Deposits - Fair Value of Available-For-Sale Investments with Gross Unrealized Losses by Investment Type and Length of Time (Details)

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Short-term and Long-term Investments, Restricted Deposits - Fair Value of Available-For-Sale Investments with Gross Unrealized Losses by Investment Type and Length of Time (Details) - USD ($)
$ in Millions
Mar. 31, 2021
Dec. 31, 2020
Unrealized Losses    
Less Than 12 Months $ (93) $ (16)
12 Months or More (6) (2)
Fair Value    
Fair Value, Less Than 12 Months 4,453 1,699
Fair Value, 12 Months or More 226 144
Corporate securities    
Unrealized Losses    
Less Than 12 Months (61) (7)
12 Months or More (3) (1)
Fair Value    
Fair Value, Less Than 12 Months 2,711 953
Fair Value, 12 Months or More 100 24
Municipal securities    
Unrealized Losses    
Less Than 12 Months (13) (2)
12 Months or More (1) 0
Fair Value    
Fair Value, Less Than 12 Months 759 238
Fair Value, 12 Months or More 13 0
Asset-backed securities    
Unrealized Losses    
Less Than 12 Months (1) (2)
12 Months or More (1) (1)
Fair Value    
Fair Value, Less Than 12 Months 296 302
Fair Value, 12 Months or More 58 105
Residential mortgage-backed securities    
Unrealized Losses    
Less Than 12 Months (8) 0
12 Months or More 0 0
Fair Value    
Fair Value, Less Than 12 Months 442 59
Fair Value, 12 Months or More 2 2
Commercial mortgage-backed securities    
Unrealized Losses    
Less Than 12 Months (10) (5)
12 Months or More (1) 0
Fair Value    
Fair Value, Less Than 12 Months 245 147
Fair Value, 12 Months or More $ 53 $ 13