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Fair Value Measurements - Fair Value of Investment Assets (Details) - USD ($) $ in Millions | Jun. 30, 2022 | Dec. 31, 2021 | Jun. 30, 2021
--- | --- | --- | ---
Fair Value |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | $ 161 | $ 164 |
Carrying Value |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Total investments at amortized cost | 163 |  | $ 156
Level 1 | Fair Value |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 87 |  | 75
Level 1 | Fair Value | Fixed Income Mutual Funds |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 87 |  | 75
Level 1 | Fair Value | Corporate Bonds |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 0 |  | 0
Level 1 | Fair Value | Government Securities |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 0 |  | 0
Level 2 | Fair Value |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 74 |  | 89
Level 2 | Fair Value | Fixed Income Mutual Funds |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 0 |  | 0
Level 2 | Fair Value | Corporate Bonds |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 52 |  | 63
Level 2 | Fair Value | Government Securities |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 22 |  | 26
Total | Fair Value |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 161 |  | 164
Total | Fair Value | Fixed Income Mutual Funds |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 87 |  | 75
Total | Fair Value | Corporate Bonds |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | 52 |  | 63
Total | Fair Value | Government Securities |  |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |  |
Commercial Paper | $ 22 |  | $ 26

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