Stock-Based Compensation Plans - Changes in Company's Common Stock Price During Reporting Period (Detail) - Stock Based Compensation Expense [Member] - $ / shares |
12 Months Ended | ||
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Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |||
| Common stock price at beginning of period | $ 26.72 | $ 29.14 | $ 33.25 |
| Common stock price at end of period | 32.61 | 26.72 | 29.14 |
| Increase (decrease) in stock price | $ 5.89 | $ (2.42) | $ (4.11) |
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- Definition Increase decrease in common stock price. No definition available.
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Price of a single share of a number of saleable stocks of a company. No definition available.
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- Details
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