Property, Plant and Equipment, Net - 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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Property Plant and Equipment Useful Life and Values [Abstract] | |||
Depreciation expense | $ 2,562,000 | $ 1,528,000 | $ 1,074,000 |