Share Capital - Deferred Share Units - Additional Information 3 (Detail) (USD $)	9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2014 Deferred Share Units [Member] Installment	Dec. 31, 2013 Deferred Share Units [Member]	Sep. 30, 2014 Directors Deferred Share Units [Member]	Sep. 30, 2013 Directors Deferred Share Units [Member]	Sep. 30, 2014 Directors Deferred Share Units [Member]	Sep. 30, 2013 Directors Deferred Share Units [Member]
Class of Stock [Line Items]
Deferred share units vesting period expressed in number of monthly installments	36
Cash payments under the DDSU Plan			$ 0	$ 0	$ 0	$ 0
Shares, vested	85,556	47,056
Shares, unvested	68,444	106,944