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Marketable Securities - Schedule of Marketable Securities (Detail) - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015
--- | --- | ---
Schedule Of Available For Sale Securities [Line Items] |  |
Market value | $ 33,058 | $ 19,260
Level 1 | Valhi Inc | Common stock |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Market value | 33,058 | 19,260
Cost basis | 24,347 | 24,347
Unrealized loss |  | $ (5,087)
Unrealized gain | $ 8,711 |

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