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Employee Benefits - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Tax Adjustments, Settlements, and Unusual Provisions | $ 114 |  |  |
Share-based Compensation Expense |  | $ 636 | $ 845 | $ 649
Stock Issued During Period, Value, Employee Stock Purchase Plan |  | 90 | 91 | 83
Deferred Compensation Arrangement with Individual, Compensation Expense |  | $ 110 | 91 | 74
Fair Value of Deferred Compensation Plan, Liabilities |  |  | 124 |
2004 Equity Incentive Plan [Member] | Common Stock [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized | 309 | 309 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 79 | 79 |  |
Stock Option |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period |  | 10 years |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value |  | $ 209 | $ 412 | $ 337
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value |  | $ 12.15 | $ 17.03 | $ 38.78
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount | $ 85 | $ 85 |  |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition |  | 2 years 1 month 6 days |  |
Stock Option | Minimum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 3 years |  |
Stock Option | Maximum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 4 years |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Granted |  | $ 64.31 | 77.98 | 73.56
Restricted Stock Units (RSUs) [Member] | Minimum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 3 years |  |
Restricted Stock Units (RSUs) [Member] | Maximum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 4 years |  |
Performance Shares |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Granted |  | $ 68.30 | $ 88.76 | $ 74.42
Performance Shares | Minimum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Other than Options, Pay-out Percentage | 0.00% | 0.00% |  |
Performance Shares | Maximum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Other than Options, Pay-out Percentage | 200.00% | 200.00% |  |
Restricted Stock and Performance Share Awards [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount | $ 802 | $ 802 |  |
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition |  | 2 years 2 months 12 days |  |
Employee Stock Purchase Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 9 | 9 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent |  | 85.00% |  |
Issuances under employee stock purchase plan, Shares |  | 2 |  |
Stock Issued During Period, Value, Employee Stock Purchase Plan |  | $ 90 |  |
Common Stock, Capital Shares Reserved for Future Issuance | 79 | 79 |  |
Deferred compensation plan | Level 1 | Fair Value, Recurring [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Marketable equity securities | $ 171 | $ 171 | $ 124 |
Fair Value at Grant Date [Member] | Restricted Stock and Performance Share Awards [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Total fair value of vested stock awards as of vesting date |  | 450 | 481 | $ 329
Fair Value at Vesting Date [Member] | Restricted Stock and Performance Share Awards [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Total fair value of vested stock awards as of vesting date |  | $ 372 | $ 446 | $ 288

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