Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

INCOME TAXES.

Income Tax (Recovery) Expense

($ millions)		2017		2016
Current:
	Current year	1 150		222
	Adjustments to current income tax of prior years	59		(69	)
Deferred:
	Origination of temporary differences	425		(313	)
	Adjustments in respect of deferred income tax of prior years	(70	)	67
	Changes in tax rates and legislation	(106	)	(190	)
	Recognition of previously unrecognized deferred tax assets	—		(76	)
		1 458		(359	)

Reconciliation of Effective Tax Rate

($ millions)		2017		2016
Earnings before income tax		5 916		86
Canadian statutory tax rate		27.01%		27.00%
Statutory tax		1 598		23
Add (deduct) the tax effect of:
	Non-taxable component of capital gains	(90	)	(60	)
	Share-based compensation and other permanent items	(1	)	19
	Assessments and adjustments	(11	)	(2	)
	Impact of income tax rate and legislative changes	(106	)	(190	)
	Foreign tax rate differential	180		(28	)
	Non-taxable component of dispositions	(41	)	—
	Tax gains for which no deferred income tax asset was recognized	(51	)	(50	)
	Recognition of deferred income tax asset previously unrecognized	—		(76	)
	Other	(20	)	5
		1 458		(359	)

Deferred Income Tax Balances

	Net Earnings (Loss)				Consolidated Balance Sheets(1)
($ millions)	2017		2016		Dec 31 2017		Dec 31 2016
Property, plant and equipment	157		(864	)	14 252		13 864
Decommissioning and restoration provision	19		342		(1 910	)	(1 701	)
Employee retirement benefit plans	(5	)	(23	)	(639	)	(648	)
Tax loss carry-forwards	—		(10	)	(109	)	(109	)
Partnership deferral reserve	—		(78	)	—		—
Foreign exchange and other	78		121		(161	)	(226	)
	249		(512	)	11 433		11 180

(1) The current and non-current portion of the deferred income tax liability and asset are as follows:

($ millions)	Dec 31 2017		Dec 31 2016
Deferred income tax liability expected to reverse within 12 months	93		195
Deferred income tax asset expected to reverse within 12 months	(27	)	(21	)
Deferred income tax liability expected to reverse after 12 months	11 440		11 048
Deferred income tax asset expected to reverse after 12 months	(73	)	(42	)
Net deferred income tax liability	11 433		11 180

Change in Deferred Income Tax Balances

($ millions)	2017		2016
Beginning of year	11 180		9 919
Recognized in deferred income tax expense	249		(512	)
Recognized in other comprehensive income	19		(5	)
Recognized in equity	—		(26	)
Acquisition	—		2 054
Foreign exchange, disposition and other	(15	)	(179	)
Reclassified to assets held for sale (notes 36 and 37)	—		(71	)
End of year	11 433		11 180

Deferred Tax in Shareholders' Equity

		Year ended December 31
($ millions)		2017		2016
Deferred Tax in Other Comprehensive (Loss) Income
	Actuarial (gain) loss on employment retirement benefit plans	(19	)	5
Deferred Tax in Equity
	Common share issuance	—		26
		(19	)	31