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Stockholder's Equity - Additional Information (Detail) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2014 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Class Of Stock [Line Items] |  |  |  |
Dividends paid | $ 0 |  |  |
NL |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Common stock awarded to board of directors |  | 14,000 | 9,000 | 9,000
Shares available for award |  | 163,000 |  |
NL | Maximum |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Aggregate of common stock awarded to directors |  | 200,000 |  |
CompX |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Shares available for award |  | 173,000 |  |
CompX | Maximum |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Aggregate of common stock awarded to directors |  | 200,000 |  |
Kronos |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Shares available for award |  | 163,500 |  |
Kronos | Maximum |  |  |  |
Class Of Stock [Line Items] |  |  |  |
Aggregate of common stock awarded to directors |  | 200,000 |  |

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