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 | |||