| Schedule of Fair Value Measurements |
The following table summarizes our fair value measurements at December 31, 2019 and 2018, respectively, for financial assets measured at fair value on a recurring basis: | | | | | | | | | | | | | | | | | | | | Fair Value Measurements Using | | Fair Value | | Quoted Prices
in Active
Markets
(Level 1) | | Other
Observable
Inputs
(Level 2) | | Unobservable
Inputs
(Level 3) | | (in millions) | December 31, 2019 | | | | | | | | Cash equivalents | $ | 3,660 |
| | $ | 3,660 |
| | $ | — |
| | $ | — |
| Debt securities: | | | | | | | | U.S. Treasury and other U.S. government corporations and agencies: | | | | | | | | U.S. Treasury and agency obligations | 354 |
| | — |
| | 354 |
| | — |
| Mortgage-backed securities | 3,710 |
| | — |
| | 3,710 |
| | — |
| Tax-exempt municipal securities | 1,463 |
| | — |
| | 1,463 |
| | — |
| Mortgage-backed securities: | | | | | | | | Commercial | 804 |
| | — |
| | 804 |
| | — |
| Asset-backed securities | 1,093 |
| | — |
| | 1,093 |
| | — |
| Corporate debt securities | 3,947 |
| | — |
| | 3,947 |
| | — |
| Total debt securities | 11,371 |
| | — |
| | 11,371 |
| | — |
| Common stock | 7 |
| | 7 |
| | — |
| | — |
| Total invested assets | $ | 15,038 |
| | $ | 3,667 |
| | $ | 11,371 |
| | $ | — |
| December 31, 2018 | | | | | | | | Cash equivalents | $ | 2,024 |
| | $ | 2,024 |
| | $ | — |
| | $ | — |
| Debt securities: | | | | | | | | U.S. Treasury and other U.S. government corporations and agencies: | | | | | | | | U.S. Treasury and agency obligations | 417 |
| | — |
| | 417 |
| | — |
| Mortgage-backed securities | 2,544 |
| | — |
| | 2,544 |
| | — |
| Tax-exempt municipal securities | 2,771 |
| | — |
| | 2,771 |
| | — |
| Mortgage-backed securities: | | | | | | | | Residential | 55 |
| | — |
| | 55 |
| | — |
| Commercial | 523 |
| | — |
| | 523 |
| | — |
| Asset-backed securities | 985 |
| | — |
| | 985 |
| | — |
| Corporate debt securities | 3,142 |
| | — |
| | 3,142 |
| | — |
| Total debt securities | 10,437 |
| | — |
| | 10,437 |
| | — |
| Total invested assets | $ | 12,461 |
| | $ | 2,024 |
| | $ | 10,437 |
| | $ | — |
|
|