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Business Combinations - Summary of Unaudited Pro Forma Historical Results (Detail) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Business Combinations [Abstract] |  |
Total revenues | $ 1,839.5 | $ 1,653.7
Net earnings attributable to controlling interests | $ 273.8 | $ 229.3
Basic net earnings per share | $ 1.51 | $ 1.28
Diluted net earnings per share | $ 1.48 | $ 1.27

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