Other Comprehensive Income (Tables)

12 Months Ended

Dec. 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
	For the years ended December 31,
($ in millions)	2018								2017									2016
	Pre-tax			Tax		After-tax			Pre-tax			Tax			After-tax			Pre-tax			Tax			After-tax
Unrealized net holding gains and losses arising during the period, net of related offsets	$	(1,142	)	$	241	$	(901	)	$	866		$	(304	)	$	562		$	486		$	(170	)	$	316
Less: reclassification adjustment of realized capital gains and losses	(186		)	39		(147		)	374			(131		)	243			(180		)	63			(117		)
Unrealized net capital gains and losses	(956		)	202		(754		)	492			(173		)	319			666			(233		)	433
Unrealized foreign currency translation adjustments	(70		)	15		(55		)	72			(25		)	47			15			(5		)	10
Unrecognized pension and other postretirement benefit cost arising during the period	(464		)	99		(365		)	232			(79		)	153			(263		)	94			(169		)
Less: reclassification adjustment of net periodic cost recognized in operating costs and expenses	(280		)	59		(221		)	(237		)	83			(154		)	(100		)	35			(65		)
Unrecognized pension and other postretirement benefit cost	(184		)	40		(144		)	469			(162		)	307			(163		)	59			(104		)
Other comprehensive (loss) income	$	(1,210	)	$	257	$	(953	)	$	1,033		$	(360	)	$	673		$	518		$	(179	)	$	339