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Investment in Kronos Worldwide, Inc. - Additional Information (Detail) - Kronos - USD ($) $ / shares in Units, shares in Millions, $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
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Schedule Of Equity Method Investments [Line Items] |  |
Number of shares owned | 35.2 | 35.2
Aggregate market value | $ 471.9 | $ 405.7
Quoted market price per share | $ 13.40 | $ 11.52

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