Income Taxes (Unaudited) (Tables)

9 Months Ended

Sep. 30, 2018

Income Tax Disclosure [Abstract]

Schedule of Income Tax Expense and Effective Income Tax Rates

	Three Months Ended September 30						Nine Months Ended September 30
$ in millions	2018			2017			2018			2017
Federal and foreign income tax expense	$	93		$	139		$	385		$	534
Effective income tax rate	7.5		%	17.8		%	13.0		%	22.4		%