COMMITMENTS AND CONTINGENCIES - COMMITMENTS (Details) $ in Millions	Dec. 31, 2020 CAD ($)
Annual debt maturities
Total	$ 65,358
Less than 1 year	2,942
2 years	10,062
3 years	2,565
4 years	7,990
5 years	5,011
Thereafter	36,788
Interest obligations
Total	34,799
Less than 1 year	2,417
2 years	2,332
3 years	2,193
4 years	2,037
5 years	1,881
Thereafter	23,939
Purchase of services, pipe and other materials, including transportation
Total	9,206
Less than 1 year	3,124
2 years	1,436
3 years	762
4 years	783
5 years	560
Thereafter	2,541
Maintenance agreements
Total	454
Less than 1 year	61
2 years	59
3 years	29
4 years	28
5 years	27
Thereafter	250
Right-of-ways commitments
Total	1,173
Less than 1 year	31
2 years	38
3 years	38
4 years	38
5 years	38
Thereafter	990
Total
Total	110,990
Less than 1 year	8,575
2 years	13,927
3 years	5,587
4 years	10,876
5 years	7,517
Thereafter	$ 64,508