income taxes (Tables)

6 Months Ended

Jun. 30, 2018

income taxes

Schedule of composition of income tax expenses

	Three months						Six months
Periods ended June 30 (millions)	2018			2017			2018			2017
				(adjusted – Note 2(c))						(adjusted – Note 2(c))
Current income tax expense
For the current reporting period	$	139		$	120		$	283		$	183
Adjustments recognized in the current period for income taxes of prior periods	(8		)	(73		)	(8		)	(79		)
	131			47			275			104
Deferred income tax expense (recovery)
Arising from the origination and reversal of temporary differences	6			25			13			105
Adjustments recognized in the current period for income taxes of prior periods	8			72			8			78
	14			97			21			183
	$	145		$	144		$	296		$	287

Schedule of reconciliation of income tax expense and effective income tax rate

Periods ended June 30 ($ in millions)	2018					2017
						(adjusted – Note 2(c))
THREE MONTH
Income taxes computed at applicable statutory rates	$	147		27.2	%	$	145		26.9	%
Adjustments recognized in the current period for income taxes of prior periods	—			—		(1		)	(0.2	)
Other	(2		)	(0.5	)	—			—
Income tax expense per Consolidated statements of income and other comprehensive income	$	145		26.7	%	$	144		26.7	%
SIX-MONTH
Income taxes computed at applicable statutory rates	$	299		27.1	%	$	295		26.7	%
Adjustments recognized in the current period for income taxes of prior periods	—			—		(1		)	(0.1	)
Other	(3		)	(0.4	)	(7		)	(0.7	)
Income tax expense per Consolidated statements of income and other comprehensive income	$	296		26.7	%	$	287		25.9	%