Stock Option Activity (Detail) (CAD) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at December 31, 2011, Shares	284
Stock options awarded, Shares	385
Options exercised, Shares
Options forfeited or expired, Shares	(25)
Outstanding at June 30, 2012	644
Exercisable at June 30, 2012	259
Balance at December 31, 2011, Weighted average exercise price	20.47
Stock options awarded, Weighted average exercise price	6.47
Options exercised, Weighted average exercise price
Options forfeited or expired, Weighted average exercise price	29.95
Outstanding at June 30, 2012, Weighted average exercise price	11.73
Exercisable at June 30, 2012, Weighted average exercise price	19.56

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

+ References

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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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

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