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Earnings Per Share - Narrative (Details) shares in Millions |  | 1 Months Ended | 12 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 17, 2019 USD ($) shares | Dec. 31, 2020 USD ($) shares | Dec. 31, 2020 USD ($) shares | Dec. 31, 2019 USD ($) shares | Dec. 31, 2018 USD ($) agreement shares | Oct. 21, 2020 USD ($) | Sep. 30, 2019 shares | Aug. 31, 2019 USD ($) | Jan. 31, 2019 USD ($) | Feb. 28, 2018 USD ($) | Oct. 31, 2017 USD ($)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share repurchase program, remaining amount |  | $ 5,900,000,000 | $ 5,900,000,000 |  |  |  |  |  |  |  |
Number of shares repurchased (in shares) | shares |  |  | 13.0 | 48.0 | 72.0 |  |  |  |  |  |
Amount of shares repurchased |  |  | $ 867,000,000 | $ 3,373,000,000 | $ 4,671,000,000 |  |  |  |  |  |
January 2019 program |  |  |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share repurchase program authorized amount |  |  |  |  |  |  |  |  | $ 5,000,000,000 |  |
Share repurchase program, remaining amount |  | $ 889,000,000 | 889,000,000 |  |  |  |  |  |  |  |
Number of shares repurchased (in shares) | shares |  | 1.1 |  |  |  |  |  |  |  |  |
Accelerated share repurchase program payment |  | $ 100,000,000 | $ 100,000,000 |  |  |  |  | $ 250,000,000 |  |  |
Accelerated share repurchase program initial shares received (in shares) | shares |  |  |  |  |  |  | 4.0 |  |  |  |
January 2019 program | Affiliated Entity | MR Argent Advisor LLC |  |  |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of shares repurchased (in shares) | shares | 4.7 |  |  |  |  |  |  |  |  |  |
Amount of shares repurchased | $ 319,000,000 |  |  |  |  |  |  |  |  |  |
October 2020 program |  |  |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share repurchase program authorized amount |  |  |  |  |  | $ 5,000,000,000 |  |  |  |  |
October 2017 program |  |  |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |  |  |
Share repurchase program authorized amount |  |  |  |  |  |  |  |  |  | $ 5,000,000,000 | $ 1,500,000,000
Number of shares repurchased (in shares) | shares |  |  |  |  | 22.0 |  |  |  |  |  |
Accelerated share repurchase program payment |  |  |  |  | $ 1,500,000,000 |  |  |  |  |  |
Number of accelerated share repurchase agreements entered into by the Company | agreement |  |  |  |  | 4 |  |  |  |  |  |

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