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Stock-based Compensation (Schedule of Stock Option Exercises) (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Stock Option Aggregate Disclosures [Abstract] |  |
Intrinsic value of stock options exercised | $ 48 | $ 138
Cash received from option exercises | 33 | 72
Treasury shares repurchased for employee payroll taxes | (8) | (22)
Tax benefit realized from option exercises | 11 | 34
Aggregate grant-date fair value of stock options vested | $ 14 | $ 15

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- Definition Amount of tax benefit from exercise of option under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=116856206&loc=SL79508275-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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