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Employee Benefits - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Expense | $ 649 | $ 380 | $ 382
Stock Issued During Period, Value, Employee Stock Purchase Plan | 83 | 84 | 86
Deferred Compensation Arrangement with Individual, Compensation Expense | 74 | 69 | 47
Fair Value of Deferred Compensation Plan, Liabilities | $ 116 | 84 |
2004 Equity Incentive Plan [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 |  |
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 | 243 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant | 98 |  |
Share Based Compensation Expense [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Other Inventory, Capitalized Costs, Gross | $ 11 | 9 | 8
Inventories [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount | $ 17 | 15 | 13
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 | $ 337 | $ 452 | $ 1,100
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value | $ 38.78 | $ 20.04 | $ 29.73
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 413 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 5 months 15 days |  |
Stock Option | Prior to 2011 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 5 years |  |
Stock Option | Starting in 2011 [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] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 1 year |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 31 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 1 year 3 months 25 days |  |
Granted | $ 74.42 | $ 71.60 | $ 61.71
Total grant date fair value of stock awards vested | $ 4 | $ 33 | $ 76
Total fair value of vested stock awards as of vesting date | 3 | 45 | 160
Share-based Compensation Expense | $ 24 | $ 20 | $ 40
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% |  |
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% |  |
Restricted Stock Units |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Weighted average grant date fair value of RSUs granted | $ 73.56 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 4 years |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 810 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition | 2 years 7 months 20 days |  |
Granted | $ 69.57 | $ 84.51 | $ 103.19
Total grant date fair value of stock awards vested | $ 325 | $ 284 | $ 249
Total fair value of vested stock awards as of vesting date | $ 285 | $ 408 | $ 666
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 | 12 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent | 85.00% |  |
Issuances under employee stock purchase plan, Shares | 1 |  |
Stock Issued During Period, Value, Employee Stock Purchase Plan | $ 83 |  |
Common Stock, Capital Shares Reserved for Future Issuance | 79 |  |

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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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