XML 146 R94.htm IDEA: XBRL DOCUMENT v3.8.0.1
Pension and other post-retirement benefits - components of net pension and other benefit expense (Details) - CAD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Disclosure of benefit plans [line items]    
Defined benefit expense $ 5,208 $ 5,128
Defined contribution pension expense 15,929 17,716
Employee benefit expense 431,559 487,349
Pension plans [member]    
Disclosure of benefit plans [line items]    
Current service cost 1,544 1,634
Interest income or cost 1,490 1,439
Administration cost 2 2
Defined benefit expense 3,036 3,075
Defined contribution pension expense 15,929 17,716
Employee benefit expense 18,965 20,791
Amount of actuarial losses (gains) recognized in other comprehensive income    
Actuarial loss (gain) 6,243 2,282
Return on assets excluding interest income 2 127
Total actuarial losses (gains) recognized in other comprehensive income 6,245 2,409
Other Benefit Plans [Member]    
Disclosure of benefit plans [line items]    
Current service cost 1,227 1,153
Interest income or cost 945 900
Administration cost 0 0
Defined benefit expense 2,172 2,053
Defined contribution pension expense 0 0
Employee benefit expense 2,172 2,053
Amount of actuarial losses (gains) recognized in other comprehensive income    
Actuarial loss (gain) 2,126 534
Return on assets excluding interest income 0 0
Total actuarial losses (gains) recognized in other comprehensive income $ 2,126 $ 534