v3.21.2
Financial Instruments (Gross Unrealized Losses and Fair Values for Investments in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
Jun. 30, 2021
Dec. 31, 2020
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value $ 34,455 $ 8,444
Less than 12 Months, Unrealized Loss (106) (15)
12 Months or Greater, Fair Value 174 245
12 Months or Greater, Unrealized Loss (1) (2)
Total Fair Value 34,629 8,689
Total Unrealized Loss (107) (17)
Government bonds    
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 19,730 5,516
Less than 12 Months, Unrealized Loss (50) (9)
12 Months or Greater, Fair Value 0 3
12 Months or Greater, Unrealized Loss 0 0
Total Fair Value 19,730 5,519
Total Unrealized Loss (50) (9)
Corporate debt securities    
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 9,681 1,999
Less than 12 Months, Unrealized Loss (24) (1)
12 Months or Greater, Fair Value 0 0
12 Months or Greater, Unrealized Loss 0 0
Total Fair Value 9,681 1,999
Total Unrealized Loss (24) (1)
Mortgage-backed and asset-backed securities    
Investments, Unrealized Loss Position [Line Items]    
Less than 12 Months, Fair Value 5,044 929
Less than 12 Months, Unrealized Loss (32) (5)
12 Months or Greater, Fair Value 174 242
12 Months or Greater, Unrealized Loss (1) (2)
Total Fair Value 5,218 1,171
Total Unrealized Loss $ (33) $ (7)