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Investments - (Tables) | 3 Months Ended
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Mar. 31, 2020
Investments, Debt and Equity Securities [Abstract] |
Amortized Cost, Gross Unrealized Gains and Losses, Fair Values of Investments | The amortized cost, gross unrealized gains, gross unrealized losses, and fair values of our AFS investments as of March 31, 2020 and December 31, 2019 are presented below.
| March 31, 2020 |  | December 31, 2019
(in millions) | Amortized Cost | Gross Unrealized Gains | Gross Unrealized Losses | Fair Value |  | Amortized Cost | Gross Unrealized Gains | Gross Unrealized Losses | Fair Value
Asset-backed securities | $ | 30 |  | $ | — |  | $ | — |  | $ | 30 |  |  | $ | 30 |  | $ | — |  | $ | — |  | $ | 30 |
Corporate bonds | 126 |  | 1 |  | (1 | ) | 126 |  |  | 123 |  | 1 |  | — |  | 124 |
U.S. government agencies and government- sponsored agencies | 24 |  | 1 |  | — |  | 25 |  |  | 14 |  | — |  | — |  | 14 |
U.S. treasuries | 239 |  | 5 |  | — |  | 244 |  |  | 163 |  | — |  | — |  | 163 |
Certificate of deposit | 1 |  | — |  | — |  | 1 |  |  | 1 |  | — |  | — |  | 1 |
Other debt securities | 8 |  | — |  | — |  | 8 |  |  | 10 |  | — |  | — |  | 10 |
Total | $ | 428 |  | $ | 7 |  | $ | (1 | ) | $ | 434 |  |  | $ | 341 |  | $ | 1 |  | $ | — |  | $ | 342 |
Fair Value of Debt Investments by Contractual Maturity | The fair value of debt investments by contractual maturity are shown below:
(in millions) | March 31, 2020
One year or less | $ | 94 |
Over one year through five years | 310 |
Over five years through ten years | 9 |
Over ten years | 21 |
Total fair value | $ | 434 |
Proceeds from available-for-sale securities | The gross proceeds from sales and maturities of AFS securities for the three months ended March 31, 2020 and March 31, 2019 are presented below. We had immaterial gross realized gains and losses from sales of investments for the three months ended March 31, 2020 and March 31, 2019.
| Three Months Ended March 31,
(in millions) | 2020 | 2019
Gross proceeds from sales | $ | 40 |  | $ | 14 |
Gross proceeds from maturities | 27 |  | 17 |
Total | $ | 67 |  | $ | 31 |

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- Definition Debt Securities, Available-For-Sale, And Equity Securities, FV-NI [Table Text Block] + References No definition available. + Details
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- Definition Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -URI http://asc.fasb.org/topic&trid=2196928 + Details
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- Definition Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments. + References No definition available. + Details
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