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Business Combinations - Summary of Unaudited Pro Forma Historical Results (Detail) - USD ($) $ / shares in Units, $ in Millions | 3 Months Ended | 9 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Business Combinations [Abstract] |  |  |  |
Total revenues | $ 1,589.3 | $ 1,517.5 | $ 4,600.0 | $ 4,317.2
Net earnings attributable to controlling interests | $ 130.1 | $ 123.4 | $ 359.8 | $ 320.4
Basic net earnings per share | $ 0.72 | $ 0.69 | $ 2.00 | $ 1.80
Diluted net earnings per share | $ 0.71 | $ 0.69 | $ 1.98 | $ 1.79

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