QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - CAD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 12,470	$ 11,466	$ 10,948	$ 12,187	$ 10,008	$ 9,110	$ 7,956	$ 12,013	$ 47,071	$ 39,087	$ 50,069
Operating income	2,053	1,388	1,816	2,548	2,251	2,095	2,098	1,513	7,805	7,957	8,260
Earnings/(loss)	1,965	814	1,521	2,014	1,899	1,104	1,777	(1,364)	6,314	3,416	5,827
Earnings/(loss) attributable to controlling interests	1,933	780	1,484	1,992	1,871	1,084	1,741	(1,333)	6,189	3,363	5,705
Earnings/(loss) attributable to common shareholders	$ 1,840	$ 682	$ 1,394	$ 1,900	$ 1,775	$ 990	$ 1,647	$ (1,429)	$ 5,816	$ 2,983	$ 5,322
Earnings/(loss) per common share
Earnings/(loss) per common share attributable to common shareholders (in CAD per share)	$ 0.91	$ 0.34	$ 0.69	$ 0.94	$ 0.88	$ 0.49	$ 0.82	$ (0.71)	$ 2.87	$ 1.48	$ 2.64
Diluted earnings/(loss) per common share attributable to common shareholders (in CAD per share)	$ 0.91	$ 0.34	$ 0.69	$ 0.94	$ 0.88	$ 0.49	$ 0.82	$ (0.71)	$ 2.87	$ 1.48	$ 2.63