Share-Based Payments (Compensation Cost Recognized and Related Income Tax Benefit for Stock Options, Restricted Stock Shares, Restricted Stock Units, and Performance Share Awards) (Details) - USD ($) $ 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] | |||
| Total Compensation Cost Recognized | $ 263 | $ 202 | $ 164 |
| Income Tax Benefit | 97 | 75 | 62 |
| Employee stock options | |||
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
| Total Compensation Cost Recognized | 12 | 19 | 21 |
| Income Tax Benefit | 5 | 7 | 8 |
| Employee restricted stock units | |||
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
| Total Compensation Cost Recognized | 142 | 126 | 111 |
| Income Tax Benefit | 51 | 47 | 42 |
| Employee performance shares and performance units | |||
| Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
| Total Compensation Cost Recognized | 109 | 57 | 32 |
| Income Tax Benefit | $ 41 | $ 21 | $ 12 |