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Derivative Financial Instruments and Hedging Transactions - Additional Information (Detail) (USD $)
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12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Derivative Instruments and Hedging Activities Disclosure [Abstract] | |||
| Gain or loss from derivatives designated as fair value hedges | $ 128,000 | $ 16,000 | $ 0 |