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Supplemental Disclosures (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |
Deferred and contingent purchase consideration from prior years' acquisition | $ 136 | $ 98 | $ 49
Deferred purchase consideration from prior years' acquisitions | 55 | 54 | 36
Contingent purchase consideration from prior years' acquisitions | 81 | 44 | 13
Net charge for adjustments related to acquisitions | 3 | 9 | 45
Payment of contingent consideration | 27 | 42 | 34
Non-cash issuance of common stock | 88 | 73 | 72
Stock-based compensation expense, equity awards | 149 | 109 | 88
Effective income tax rate reconciliation, share-based compensation, excess tax benefit, amount | $ 79 |  |
Adjustments to additional paid in capital, income tax benefit from share-based compensation |  | 44 | $ 53
Putnam |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |
Cash used in operating activities, discontinued operations |  | $ 82 |

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