Summary of Changes in Outstanding Options (Detail)	9 Months Ended
Sep. 30, 2015 shares
Number of Shares
Number of Options, Outstanding at December 31, 2014	153,764
Number of Options, Exercised	(113,352)
Number of Options, Outstanding at September 30, 2015	40,412

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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