Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure of employee benefits [text block] [Abstract]

Schedule of expenses included on consolidated statements of income and consolidated statements of comprehensive income

For the year ended December 31, 2021	Pension Plans									Other Post-employment Benefit Plans
	Canadian			US			Total			Canadian		US			Total
Consolidated statements of income
Operating expenses	$	7,893		$	74		$	7,967		$	166	$	—		$	166
Interest expense	$	743		$	53		$	796		$	552	$	92		$	644
Consolidated statements of comprehensive income
Actuarial (gains) losses on employee benefit plans	$	(55,582	)	$	(798	)	$	(56,380	)	$	987	$	(29	)	$	958

	Canadian Pension Plans		Other Post-employment Benefit Plans
For the year ended December 31, 2020			Canadian		US		Total
Consolidated statements of income
Operating expenses	$	7,188	$	145	$	—	$	145
Interest expense	$	423	$	618	$	128	$	746
Consolidated statements of comprehensive income
Actuarial losses on employee benefit plans	$	11,390	$	1,686	$	617	$	2,303

	Canadian Pension Plans			Other Post-employment Benefit Plans
For the year ended December 31, 2019				Canadian		US		Total
Consolidated statements of income
Operating expenses	$	6,198		$	116	$	—	$	116
Interest expense	$	524		$	665	$	150	$	815
Consolidated statements of comprehensive income
Actuarial (gains) losses on employee benefit plans	$	(3,325	)	$	1,533	$	658	$	2,191

Schedule of balance sheet obligations, distributed between pension and other post-employment benefits

As at December 31,	2021		2020
Included in other long-term liabilities
Pension benefits	$	17,927	$	22,070
Other post-employment benefits		27,294		25,914
Accrued benefit liabilities (Note 23)	$	45,221	$	47,984
Included in other long-term assets
Pension benefits (Note 15)	$	30,105	$	—

Schedule of funded statuses of the benefit plans and accrued benefit liabilities balance

	Pension Plans								Other Post-employment Benefit Plans
As at December 31, 2021	Canadian			US		Total			Canadian		US		Total
Present value of funded obligations	$	348,526		$	72,906	$	421,432		$	—	$	—	$	—
Fair value of plan assets		(379,740)			(54,979)		(434,719)			—		—		—
		(31,214	)		17,927		(13,287	)		—		—		—
Present value of unfunded obligations		1,109			—		1,109			22,429		4,865		27,294
(Pension benefits) accrued benefit liabilities	$	(30,105	)	$	17,927	$	(12,178	)	$	22,429	$	4,865	$	27,294

	Pension Plans								Other Post-employment Benefit Plans
As at December 31, 2020	Canadian			US		Total			Canadian		US		Total
Present value of funded obligations	$	375,222		$	—	$	375,222		$	—	$	—	$	—
Fair value of plan assets		(354,385	)		—		(354,385	)		—		—		—
		20,837			—		20,837			—		—		—
Present value of unfunded obligations		1,233			—		1,233			21,403		4,511		25,914
Accrued benefit liabilities	$	22,070		$	—	$	22,070		$	21,403	$	4,511	$	25,914

Schedule of changes in benefit obligations and fair value of plan assets

	Pension Plans									Other Post-employment Benefit Plans
As at December 31, 2021	Canadian			US			Total			Canadian			US			Total
Change in benefits obligations
Benefit obligation, January 1, 2021	$	376,455		$	—		$	376,455		$	21,403		$	4,511		$	25,914
Initial balance from transaction		—			74,113			74,113			—			646			646
Current service cost		7,462			74			7,536			166			—			166
Interest expense		9,872			235			10,107			552			92			644
Remeasurements
Actuarial gains arising from plan experience		(556	)		(70	)		(626	)		4,895			246			5,141
Actuarial gains from change in demographic assumptions		—			—			—			—			(1	)		(1	)
Actuarial gains from changes in financial assumptions		(33,099	)		(942	)		(34,041	)		(3,908	)		(274	)		(4,182	)
Benefits paid		(11,067	)		(488	)		(11,555	)		(590	)		(388	)		(978	)
Contributions by plan participants		1,001			1			1,002			—			—			—
Foreign exchange & other		(433	)		(17	)		(450	)		(89	)		33			(56	)
Benefit obligation, December 31, 2021		349,635			72,906			422,541			22,429			4,865			27,294
Change in fair value of plan assets
Fair value of plan assets, January 1, 2021		(354,385	)		—			(354,385	)		—			—			—
Initial balance from Transaction		—			(55,511	)		(55,511	)		—			—			—
Contributions by plan participants		(1,001	)		(1	)		(1,002	)		—			—			—
Contributions by employer		(4,796	)		—			(4,796	)		590			388			978
Interest income		(9,129	)		(182	)		(9,311	)		—			—			—
Benefits paid		11,067			488			11,555			(590	)		(388	)		(978	)
Remeasurements
Return on plan assets, excluding interest income		(21,927	)		214			(21,713	)		—			—			—
Administrative costs		431			—			431			—			—			—
Foreign exchange & other		—			13			13			—			—			—
Fair value of plan assets, December 31, 2021		(379,740	)		(54,979	)		(434,719	)		—			—			—
(Pension benefits) accrued benefit liabilities, December 31, 2021	$	(30,105	)	$	17,927		$	(12,178	)	$	22,429		$	4,865		$	27,294

As at December 31, 2020	Canadian Pension Plans			Other Post-employment Benefit Plans
				Canadian			US			Total
Change in benefits obligations
Benefit obligation, January 1, 2020	$	332,823		$	19,399		$	4,109		$	23,508
Current service cost		6,695			145			—			145
Interest expense		10,723			618			128			746
Remeasurements
Actuarial gains arising from plan experience		2,212			—			184			184
Actuarial gains from change in demographic assumptions		—			—			11			11
Actuarial gains from changes in financial assumptions		33,278			1,735			373			2,108
Benefits paid		(10,294	)		(494	)		(232	)		(726	)
Contributions by plan participants		1,018			—			—			—
Foreign exchange		—			—			(62	)		(62	)
Benefit obligation, December 31, 2020		376,455			21,403			4,511			25,914
Change in fair value of plan assets
Fair value of plan assets, January 1, 2020		(324,257	)		—			—			—
Contributions by plan participants		(1,018	)		—			—			—
Contributions by employer		(5,497	)		(494	)		(232	)		(726	)
Interest income		(10,300	)		—			—			—
Benefits paid		10,294			494			232			726
Remeasurements
Return on plan assets, excluding interest income		(24,100	)		—			—			—
Administrative costs		493			—			—			—
Fair value of plan assets, December 31, 2020		(354,385	)		—			—			—
Accrued benefit liabilities, December 31, 2020	$	22,070		$	21,403		$	4,511		$	25,914

Schedule of estimated future benefit payments for defined benefit pension plans and other post-employment benefit plans

	Pension Plans		Other Post-employment Benefit Plans
2022	$	15,169	$	1,056
2023	$	15,361	$	1,072
2024	$	16,416	$	1,222
2025	$	17,244	$	1,263
2026	$	18,232	$	1,298
2027 to 2031	$	101,879	$	7,121

Schedule of significant assumptions adopted in measuring pension and other benefit obligations

As at December 31,	2021		2020
Equity securities
Canada	22.8	%	22.9	%
United States	19.3	%	19.7	%
International (other than United States)	13.5	%	14.3	%
Fixed income instruments
Canada	42.3	%	41.0	%
Cash and cash equivalents	2.1	%	2.1	%

As at December 31,	2021
Equity securities
United States	33.4	%
International	22.8	%
Fixed income instruments
United States	29.9	%
Canada	0.4	%
International	4.8	%
Other investments
United States	4.4	%
International	4.3	%

Schedule of impact on defined benefit obligation from one percent increase or decrease change in assumptions used

	Canadian	US	Canadian
As at December 31,	2021	2021	2020
Actuarial benefit obligation
Discount rate	3.20%	2.85%	2.60	%
Benefit costs for the year ended
Discount rate	2.80%	2.75%	3.20	%
Future salary growth	2.50%	N/A	2.50	%

Schedule of other post-employment benefit plans

	Canadian		US
As at December 31,	2021	2020	2021	2020
Benefit costs for the year ended
Discount rate	3.20%	3.20%	2.50% to 2.85%	2.95	%
Health care cost trend rate	3.49% to 5.49%	3.49% to 5.49%	N/A	N/A
Other medical trend rates	4.00% to 4.56%	4.00% to 4.56%	N/A	N/A

Schedule of impact on defined benefit obligation from one percent increase or decrease change in assumptions

	Canadian						US
As at December 31, 2021	1% increase			1% decrease			1% increase			1% decrease
Discount rate	$	(45,732	)	$	58,488		$	(8,418	)	$	10,317
Future salary growth	$	8,606		$	(6,839	)		N/A			N/A

	Canadian
As at December 31, 2020	1% increase			1% decrease
Discount rate	$	(53,058	)	$	67,549
Future salary growth	$	10,423		$	(9,165	)

	Canadian						US
As at December 31, 2021	1% increase			1% decrease			1% increase			1% decrease
Discount rate	$	(2,961	)	$	3,734		$	(408	)	$	474
Medical and dental trend rates	$	2,216		$	(1,826	)		N/A			N/A

	Canadian						US
As at December 31, 2020	1% increase			1% decrease			1% increase			1% decrease
Discount rate	$	(3,067	)	$	3,860		$	(419	)	$	491
Medical and dental trend rates	$	2,222		$	(1,839	)		N/A			N/A