PENSION AND OTHER POSTRETIREMENT BENEFITS PENSION AND OTHER POSTRETIREMENT BENEFITS - AMOUNT RECOGNIZED IN EXCESS OF ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - CAD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Canada
Pension and Other Postretirement Benefit Disclosures
Projected benefit obligations	$ 1,481	$ 1,422
Accumulated benefit obligations	1,361	1,299
Fair value of plan assets	1,087	1,064
United States
Pension and Other Postretirement Benefit Disclosures
Projected benefit obligations	103	1,214
Accumulated benefit obligations	98	1,179
Fair value of plan assets	$ 0	$ 1,045

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Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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