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Earnings Per Share - Narrative (Details) shares in Thousands | 1 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Feb. 28, 2018 USD ($) | Jul. 31, 2017 USD ($) | Dec. 31, 2018 USD ($) agreement shares | Dec. 31, 2017 shares | Dec. 30, 2016 shares | Jan. 16, 2019 USD ($) | Oct. 25, 2017 USD ($) | Apr. 30, 2017 USD ($) | Apr. 30, 2015 USD ($)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Number of shares received under accelerate share repurchase agreements (in shares) | shares |  |  | 72,000 | 39,000 | 38,000 |  |  |  |
2018 |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Number of accelerated share repurchase agreements entered into by the Company | agreement |  |  | 4 |  |  |  |  |  |
Amount paid under accelerated share repurchase agreements |  |  | $ 1,500,000,000 |  |  |  |  |  |
Number of shares received under accelerate share repurchase agreements (in shares) | shares |  |  | 22,000 |  |  |  |  |  |
Share Repurchase Program April 2015 |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Share repurchase program |  |  |  |  |  |  |  |  | $ 2,000,000,000
Share Repurchase Program April 2017 |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Share repurchase program |  |  |  |  |  |  |  | $ 1,000,000,000 |
Share repurchase program, additional authorized amount |  | $ 500,000,000 |  |  |  |  |  |  |
Share Repurchase Program October 2017 |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Share repurchase program | $ 5,000,000,000 |  |  |  |  |  | $ 1,500,000,000.0 |  |
Share repurchase program, additional authorized amount | $ 1,500,000,000 |  |  |  |  |  |  |  |
Share Repurchase Program January 2019 | Subsequent Event |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Share repurchase program |  |  |  |  |  | $ 5,000,000,000 |  |  |
Stock Options |  |  |  |  |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |  |  |  |  |  |  |  |
Antidilutive securities (in shares) | shares |  |  | 479 | 7,600 | 2,800 |  |  |  |

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