Pension and other PostRetirement Benefits (Tables)

12 Months Ended

Dec. 31, 2017

PENSIONS AND OTHER POST RETIREMENT BENEFITS

Schedule of defined benefit obligations and funded status

			Pension Benefits				Other Post-Retirement Benefits
($ millions)			2017		2016		2017		2016
Change in benefit obligation
	Benefit obligation at beginning of year		6 280		4 611		587		502
	Obligations acquired through acquisition of COS (note 7)		—		1 352		—		73
	Current service costs		193		189		14		13
	Plan participants' contributions		14		14		—		—
	Benefits paid		(294	)	(272	)	(21	)	(21	)
	Interest costs		236		238		22		23
	Disposal (note 36)		(69	)	—		(9	)	—
	Foreign exchange		(2	)	(46	)	(1	)	(1	)
	Settlements		7		8		—		—
	Actuarial remeasurement:
		Experience loss (gain) arising on plan liabilities	2		7		(12	)	(5	)
		Actuarial (gain) loss arising from changes in demographic assumptions	(4	)	8		(9	)	(1	)
		Actuarial loss arising from changes in financial assumptions	354		171		26		4
Benefit obligation at end of year			6 717		6 280		597		587
Change in plan assets
	Fair value of plan assets at beginning of year		5 356		4 040		—		—
	Assets acquired through acquisition of COS (note 7)		—		1 060		—		—
	Employer contributions		160		165		—		—
	Plan participants' contributions		14		14		—		—
	Benefits paid		(269	)	(249	)	—		—
	Disposal (note 36)		(71	)	—		—		—
	Foreign exchange		(3	)	(37	)	—		—
	Settlements		7		8		—		—
	Administrative costs		(2	)	(2	)	—		—
	Income on plan assets		200		202		—		—
	Actuarial remeasurement:
		Return on plan assets greater than discount rate	407		155		—		—
Fair value of plan assets at end of year			5 799		5 356		—		—
Net unfunded obligation			918		924		597		587

Schedule of defined benefit plan expenses

		Pension Benefits		Other Post-Retirement Benefits
($ millions)		2017	2016	2017	2016
Analysis of amount charged to earnings:
	Current service costs	193	189	14	13
	Interest costs	36	36	22	23
Defined benefit plans expense		229	225	36	36
Defined contribution plans expense		74	76	—	—
Total benefit plans expense charged to earnings		303	301	36	36

Components of defined benefit costs recognized in Other Comprehensive Income:

	Pension Benefits				Other Post-Retirement Benefits
($ millions)	2017		2016		2017		2016
Return on plan assets (excluding amounts included in net interest expense)	(407	)	(155	)	—		—
Experience loss (gain) arising on plan liabilities	2		7		(12	)	(5	)
Actuarial loss arising from changes in financial assumptions	354		171		26		4
Actuarial (gain) loss arising from changes in demographic assumptions	(4	)	8		(9	)	(1	)
Actuarial (gain) loss recognized in other comprehensive income	(55	)	31		5		(2	)

Schedule of weighted average actuarial assumptions

	Pension Benefits		Other Post-Retirement Benefits
(%)	Dec 31 2017	Dec 31 2016	Dec 31 2017	Dec 31 2016
Discount rate	3.40	3.90	3.40	3.80
Rate of compensation increase	3.00	3.20	3.00	3.00

Schedule of changes in assumed assumptions

		Pension Benefits
($ millions)		Increase		Decrease
1% change in discount rate
	Effect on the aggregate service and interest costs	(19	)	24
	Effect on the benefits obligations	(859	)	1 107

		Other Post-Retirement Benefits
($ millions)		Increase		Decrease
1% change in discount rate
	Effect on the benefits obligations	(72	)	89
1% change in health care cost
	Effect on the aggregate service and interest costs	1		(1	)
	Effect on the benefits obligations	30		(25	)

Schedule of weighted average pension plan asset allocations based on market value

The company's weighted average pension plan asset allocations, based on market values as at December 31, are as follows:

(%)		2017	2016
Equities, comprised of:
	– Canada	18	19
	– United States	19	23
	– Foreign	19	17
		56	59
Fixed income, comprised of:
	– Canada	39	39
Real estate, comprised of:
	– Canada	5	2
Total		100	100