Other Comprehensive Income (Tables)

3 Months Ended

Mar. 31, 2018

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Other comprehensive income (loss) on a pre-tax and after-tax basis

Components of other comprehensive income (loss) on a pre-tax and after-tax basis
($ in millions)	Three months ended March 31,
	2018									2017
	Pre-tax			Tax			After-tax			Pre-tax			Tax			After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$	(740	)	$	155		$	(585	)	$	444		$	(155	)	$	289
Less: reclassification adjustment of realized capital gains and losses	(25		)	5			(20		)	132			(46		)	86
Unrealized net capital gains and losses	(715		)	150			(565		)	312			(109		)	203
Unrealized foreign currency translation adjustments	(5		)	1			(4		)	(5		)	2			(3		)
Unrecognized pension and other postretirement benefit cost arising during the period	3			(1		)	2			—			—			—
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	(26		)	5			(21		)	(29		)	10			(19		)
Unrecognized pension and other postretirement benefit cost	29			(6		)	23			29			(10		)	19
Other comprehensive (loss) income	$	(691	)	$	145		$	(546	)	$	336		$	(117	)	$	219