Summary of Changes in Outstanding Options (Detail)	3 Months Ended
Mar. 31, 2015
Number of Shares
Number of Options, Outstanding at December 31, 2014	153,764
Number of Options, Exercised	(56,152)
Number of Options, Outstanding at March 31, 2015	97,612

Number of share options (or share units) exercised during the current period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Period Type:	duration