Consolidated statement of cash flows - CAD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net income (loss)		$ 366	$ (526)	$ 758	$ (714)
Adjustments for non-cash items:
Depreciation and depletion		450	413	944	866
Impairment of intangible assets (note 11)					20
(Gain) loss on asset sales (note 3)		(24)	(10)	(27)	(17)
Inventory write-down to current market value (note 11)			(281)
Deferred income taxes and other		76	(242)	136	(199)
Changes in operating assets and liabilities:
Accounts receivable		(775)	(310)	(1,244)	833
Inventories, materials, supplies and prepaid expenses		58	117	(101)	(82)
Income taxes payable		21	(2)	42	(106)
Accounts payable and accrued liabilities		655	(46)	1,239	(1,074)
All other items - net	[1]	25	71	150	80
Cash flows from (used in) operating activities		852	(816)	1,897	(393)
Investing activities
Additions to property, plant and equipment		(241)	(205)	(408)	(515)
Proceeds from asset sales (note 3)		35	40	42	49
Loans to equity companies - net		(1)	(7)	12	(14)
Cash flows from (used in) investing activities		(207)	(172)	(354)	(480)
Financing activities
Short-term debt - net		0	0	(36)	0
Reduction in finance lease obligations (note 6)		(4)	(5)	(8)	(12)
Dividends paid		(161)	(162)	(323)	(326)
Common shares purchased (note 9)		(1,171)	0	(1,171)	(274)
Cash flows from (used in) financing activities		(1,336)	(167)	(1,538)	(612)
Increase (decrease) in cash		(691)	(1,155)	5	(1,485)
Cash at beginning of period		1,467	1,388	771	1,718
Cash at end of period	[2]	$ 776	$ 233	$ 776	$ 233

[1] Included contributions to registered pension plans. (42) (41) (70) (100)

[2] Cash is composed of cash in bank and cash equivalents at cost. Cash equivalents are all highly liquid securities with maturity of three months or less when purchased.