Securities (Details) CAD in Thousands, $ in Thousands	Oct. 25, 2013 CAD time_deposit	Apr. 30, 2016 USD ($)	Oct. 28, 2015 CAD	Apr. 25, 2015 USD ($)	Oct. 24, 2014 CAD
Schedule of Held-to-maturity Securities [Line Items]
Number of time deposits | time_deposit	3
Total principal amount	CAD 110,000		CAD 65,000		CAD 45,000
Short-term investments		$ 0		$ 53,372	CAD 45,436
Maturity value of time deposits			CAD 67,031
Short-term Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Total principal amount | $				$ 53,372