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Income Taxes - Aggregate Current and Deferred Income Tax Charged to Equity (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Net impact related to cash flow hedges	$ (12)	$ (108)	$ 51
Net impact related to net investment hedges	0	(7)	16
Net actuarial gains (losses)	5	(4)	4
Income tax expense reported in equity	$ (7)	$ (119)	$ 71

X

- Definition

The aggregate current and deferred tax relating to particular items that are charged or credited directly to equity, for example: (a) an adjustment to the opening balance of retained earnings resulting from either a change in accounting policy that is applied retrospectively or the correction of an error; and (b) amounts arising on initial recognition of the equity component of a compound financial instrument. [Refer: Deferred tax relating to items credited (charged) directly to equity; Retained earnings; Financial instruments, class [member]]

+ References

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X

- Definition

The amount of income tax relating to amounts recognised in other comprehensive income in relation to cash flow hedges. [Refer: Cash flow hedges [member]; Other comprehensive income]

+ References

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- Definition

The amount of income tax relating to amounts recognised in other comprehensive income in relation to remeasurements of defined benefit plans. [Refer: Other comprehensive income; Reserve of remeasurements of defined benefit plans; Defined benefit plans [member]]

+ References

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- Definition

Income Taxes [Abstract]

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- Definition

Income tax relating to hedges of investments in equity instruments

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