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Business Combinations - Summary of Unaudited Pro Forma Historical Results (Detail) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Business Combinations [Abstract] |  |
Total revenues | $ 7,125.5 | $ 6,572.4
Net earnings attributable to controlling interests | $ 646.1 | $ 496.4
Basic earnings per share | $ 3.53 | $ 2.74
Diluted earnings per share | $ 3.46 | $ 2.71

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