financing costs (Details) - CAD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Interest expense
Long-term debt, excluding lease liabilities - gross	$ 298	$ 270	$ 595	$ 533
Interest expense on long-term debt, excluding lease liabilities - capitalized	(4)	(1)	(4)	(3)
Long-term debt, excluding lease liabilities	294	269	591	530
Lease liabilities	40	31	80	59
Short-term borrowings and other	9	9	10	12
Accretion on provisions	7	7	15	15
Total	350	316	696	616
Employee defined benefit plans net interest	2	2	4	4
Foreign exchange	3		(6)	4
Unrealized changes in virtual power purchase agreements forward element	37	7	103	26
Total	392	325	797	650
Interest income	(10)	(2)	(21)	(7)
Net	382	323	776	643
Net interest cost			673	616	$ 1,329	$ 1,084
Interest expense on long-term debt, excluding lease liabilities - capitalized	(4)	(1)	(4)	(3)
Employee defined benefit plans net interest	2	2	4	4
Unrealized changes in virtual power purchase agreements forward element	$ 37	$ 7	$ 103	$ 26
Composite interest rate on long-term debt, excluding lease liabilities (as a percent)			5.30%	3.10%

The weighted average of interest and other costs that an entity incurs in connection with the borrowing of funds applicable to the borrowings of the entity that are outstanding during the period, other than borrowings made specifically for the purpose of obtaining a qualifying asset. [Refer: Weighted average [member]; Borrowings]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 23
-IssueDate 2023-01-01
-Paragraph 26
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=23&code=ifrs-tx-2023-en-r&anchor=para_26_b&doctype=Standard
-URIDate 2023-03-23