Income Taxes (Unaudited) (Tables)

9 Months Ended

Sep. 30, 2017

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	2017			2016			2017			2016
Federal and foreign income tax expense	$	140		$	167		$	528		$	500
Effective income tax rate	17.8		%	21.7		%	22.3		%	23.0		%