Fair Value - Supplemental Information Regarding Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions |
Dec. 31, 2021 |
Dec. 31, 2020 |
---|---|---|
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | $ 179 | $ 105 |
Gross Unrealized Gains | 1 | 5 |
Gross Unrealized Losses | (2) | |
Estimated Fair Value | 178 | 110 |
Government | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 83 | 48 |
Gross Unrealized Gains | 1 | 2 |
Gross Unrealized Losses | (1) | |
Estimated Fair Value | 83 | 50 |
Corporate | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 62 | 38 |
Gross Unrealized Gains | 2 | |
Gross Unrealized Losses | (1) | |
Estimated Fair Value | 61 | 40 |
Mortgage and Asset-Backed Securities | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 34 | 19 |
Gross Unrealized Gains | 1 | |
Estimated Fair Value | $ 34 | $ 20 |