employee future benefits - Disaggregation of defined benefit pension (Details) - Pension plans - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Defined benefit pension plans - funded status overview
PBSR prior year interim estimate of solvency position		$ 375
PBSR composite weighted average discount rate	2.90%	2.50%
Hypothetical basis points decrease in PBSR composite weighted average discount rate (as a per cent)	0.25%	0.25%
Decrease in the PBSR solvency position with hypothetical decrease of 25 basis points in the composite weighted average discount rate	$ 297	$ 330
Minimum
Defined benefit pension plans - funded status overview
PBSR interim solvency ratio	106.00%	95.00%
PBSR annual solvency ratio		94.00%
PBSR interim three-year solvency ratio	99.00%	97.00%
PBSR annual three-year solvency ratio		96.00%
Maximum
Defined benefit pension plans - funded status overview
PBSR interim solvency ratio	122.00%	109.00%
PBSR annual solvency ratio		108.00%
PBSR interim three-year solvency ratio	113.00%	109.00%
PBSR annual three-year solvency ratio		108.00%
Present value of the defined benefit obligations
Defined benefit pension plans - funded status overview
Defined benefit obligations - Difference between actual results and estimated plan assumptions	$ (456)	$ (67)
Mortality rate
Defined benefit pension plans - funded status overview
Defined benefit obligations - Difference between actual results and estimated plan assumptions	$ 375

The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in demographic assumptions that result in remeasurements of the net defined benefit liability (asset). Demographic assumptions deal with matters such as: (a) mortality; (b) rates of employee turnover, disability and early retirement; (c) the proportion of plan members with dependants who will be eligible for benefits; (d) the proportion of plan members who will select each form of payment option available under the plan terms; and (e) claim rates under medical plans. [Refer: Net defined benefit liability (asset)]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2021-01-01
-Paragraph 141
-Subparagraph c
-Clause ii
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-URIDate 2021-03-24

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

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The annual solvency ratios in the calculation of annual solvency position required by Pension Benefits Standards Regulations, 1985.

+ References

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The annual three-year solvency ratios in the calculation of annual solvency position required by Pension Benefits Standards Regulations, 1985.

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The composite weighted average discount rate in the calculation of solvency position required by Pension Benefits Standards Regulations, 1985.

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- Definition

The amount of prior year interim solvency position as required by Pension Benefits Standards Regulations, 1985 (PBSR).

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The decrease in solvency position that would have been caused by hypothetical basis points decrease in the composite weighted average discount rate in the calculation of solvency position required by Pension Benefits Standards Regulations, 1985.

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- Definition

The hypothetical basis points decrease in the composite weighted average discount rate in the calculation of solvency position required by Pension Benefits Standards Regulations, 1985.

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- Definition

The interim estimated solvency ratios in the calculation of interim solvency position required by Pension Benefits Standards Regulations, 1985.

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The interim estimated three-year solvency ratios in the calculation of interim solvency position required by Pension Benefits Standards Regulations, 1985.

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