Stock-Based Compensation - Summary of Activity Related to Employee PSUs (Detail) - Performance Share Unit Plan [Member] $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023 CAD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Units, Outstanding as of December 31, 2022 | shares	176
Number of Units, Granted including DRIP | shares	73
Number of Units, Exercised | shares	(70)
Number of Units, Forfeited | shares	(5)
Number of Units, Transferred | shares	(31)	[1]
Number of Units, Outstanding as of December 31, 2023 | shares	143
Weighted Average Grant Date Fair Value, Outstanding as of December 31, 2022 | $ / shares	$ 56.21
Weighted Average Grant Date Fair Value, Granted including DRIP | $ / shares	52.83
Weighted Average Grant Date Fair Value, Exercised | $ / shares	54.62
Weighted Average Grant Date Fair Value, Forfeited | $ / shares	54.72
Weighted Average Grant Date Fair Value, Transferred | $ / shares	56.17	[1]
Weighted Average Grant Date Fair Value, Outstanding as of December 31, 2023 | $ / shares	$ 55.32
Aggregate Intrinsic Value, Outstanding as of December 31, 2022 | $	$ 9
Aggregate Intrinsic Value, Granted including DRIP | $	4
Aggregate Intrinsic Value, Exercised | $	4
Aggregate Intrinsic Value, Forfeited | $	0
Aggregate Intrinsic Value, Transferred | $	2	[1]
Aggregate Intrinsic Value, Outstanding as of December 31, 2023 | $	$ 7

[1] This amount includes 38,197 units transferred to PGS upon their separation from TEC on January 1, 2023.