Income Taxes - Summary of Provision for Income Taxes (Detail) - CAD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Current
Current taxes on profits for the year	$ 697	$ 1,009
Adjustments for current taxes of prior periods	(6)	(15)
Total current taxes	691	994
Deferred
Origination and reversal of temporary differences	686	436
Adjustments to deferred taxes of prior periods	(16)	23
Tax losses not recognized (recognition of previously unrecognized losses)	4	(9)
Effect due to tax legislative changes		(19)
Total deferred taxes	674	431
Provision for income taxes	$ 1,365	$ 1,425

Adjustments of tax expense (income) recognised in the period for current tax of prior periods.

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Adjustments of tax expense (income) recognised in the period for the deferred tax of prior periods.

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The amount of income taxes payable (recoverable) in respect of the taxable profit (tax loss) for a period.

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The amount of current tax expense (income) and adjustments for the current tax of prior periods. [Refer: Current tax expense (income); Adjustments for current tax of prior periods]

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The amount of tax expense (income) relating to changes in deferred tax liabilities and deferred tax assets. [Refer: Deferred tax assets; Deferred tax liabilities]

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The amount of deferred tax expense or income relating to the creation or reversal of temporary differences. [Refer: Temporary differences [member]; Deferred tax expense (income)]

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The amount of deferred tax expense or income relating to tax rate changes or the imposition of new taxes. [Refer: Deferred tax expense (income)]

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The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

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