Employee Benefit Plans - Additional Information (Detail) - USD ($)
$ in Millions |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Compensation And Retirement Disclosure [Abstract] |
|
|
|
|
| Defined contribution pension plans |
|
$ 2.5
|
$ 2.4
|
$ 2.1
|
| CMRT |
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|
|
| Compensation And Retirement Disclosure [Abstract] |
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| Average annual rate of return (including the CMRT's investment in TIMET common stock) |
|
|
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14.00%
|
| Percentage of assets valued using observable inputs from level one or level two |
|
81.00%
|
80.00%
|
|
| Defined Benefit Pension Plans |
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|
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| Compensation And Retirement Disclosure [Abstract] |
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| Expected contributions to Defined Benefit Plans in Next Fiscal Year |
|
$ 0.7
|
|
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| Actuarial losses expected to be recognized as a component of net period cost in next fiscal year |
|
$ 1.5
|
|
|
| Weighted-average rate determining the actuarial present value of benefit obligation |
|
4.00%
|
3.80%
|
|
| Long-term return on plan assets |
|
7.20%
|
7.20%
|
9.20%
|
| Weighted average discount rate, periodic benefit cost |
|
3.80%
|
4.50%
|
3.70%
|
| Defined Benefit Pension Plans | CMRT |
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| Compensation And Retirement Disclosure [Abstract] |
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| Long-term return on plan assets |
|
|
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10.00%
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| Long-term return on plan assets next twelve months |
|
|
7.50%
|
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| OPEB |
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|
|
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| Compensation And Retirement Disclosure [Abstract] |
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| Expected contributions to Defined Benefit Plans in Next Fiscal Year |
|
$ 0.5
|
|
|
| Weighted-average rate determining the actuarial present value of benefit obligation |
|
3.20%
|
3.00%
|
|
| Eligible age for health care benefits |
|
65 years
|
|
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| Weighted average discount rate, periodic benefit cost |
|
3.00%
|
3.20%
|
2.50%
|
| OPEB | Scenario Forecast |
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| Compensation And Retirement Disclosure [Abstract] |
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| Actuarial losses expected to be recognized as a component of net period cost in next fiscal year |
$ 0.2
|
|
|
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| Prior service credit |
$ 0.5
|
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