10 income taxes


	Three months				Six months
Periods ended June 30 (millions)	2019		2018		2019		2018
Current income tax expense
For the current reporting period	$	71	$	139	$	197	$	283
Adjustments recognized in the current period for income taxes of prior periods		(1)		(8)		(1)		(8)
		70		131		196		275
Deferred income tax expense
Arising from the origination and reversal of temporary differences		83		6		114		13
Revaluation of deferred income tax liability to reflect future income tax rates		(121)		—		(121)		—
Adjustments recognized in the current period for income taxes of prior periods		(1)		8		(1)		8
		(39)		14		(8)		21
	$	31	$	145	$	188	$	296

Our income tax expense and effective income tax rate differ from those calculated by applying the applicable statutory rates for the following reasons:


Three-month periods ended June 30 ($ in millions)	2019				2018
Income taxes computed at applicable statutory rates	$	147	26.7	%	$	147	27.2	%
Revaluation of deferred income tax liability to reflect future income tax rates		(121)	(22.0)			—	—
Adjustments recognized in the current period for income taxes of prior periods		(2)	(0.3)			—	—
Other		7	1.2			(2)	(0.5)
Income tax expense per Consolidated statements of income and other comprehensive income	$	31	5.6	%	$	145	26.7	%

Six-month periods ended June 30 ($ in millions)	2019				2018
Income taxes computed at applicable statutory rates	$	308	26.9	%	$	299	27.1	%
Revaluation of deferred income tax liability to reflect future income tax rates		(121)	(10.6)			—	—
Adjustments recognized in the current period for income taxes of prior periods		(2)	(0.2)			—	—
Other		3	0.3			(3)	(0.4)
Income tax expense per Consolidated statements of income and other comprehensive income	$	188	16.4	%	$	296	26.7	%