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Earnings Per Share - Additional Information (Detail) (Employee Stock Option [Member])
In Millions, unless otherwise specified |
3 Months Ended | |
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Mar. 31, 2015
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Mar. 31, 2014
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Employee Stock Option [Member]
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| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
| Number of common stock excluded from calculation of diluted EPS | 0.4 | 0.2 |