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Acquisitions (Pro-Forma Information) (Details) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 | Jun. 30, 2017 | Jun. 30, 2018 | Jun. 30, 2017
Business Combinations [Abstract] |  |  |  |
Revenue | $ 3,748 | $ 3,539 | $ 7,770 | $ 7,098
Net income attributable to the Company | $ 532 | $ 503 | $ 1,225 | $ 1,072
Basic net income per share: |  |  |  |
Basic net income per share attributable to the Company (in dollars per share) | $ 1.05 | $ 0.98 | $ 2.41 | $ 2.08
Diluted net income per share: |  |  |  |
Diluted net income per share attributable to the Company (in dollars per share) | $ 1.04 | $ 0.97 | $ 2.39 | $ 2.06

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