Quarterly Results (unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Quarterly results

	First Quarter				Second Quarter				Third Quarter				Fourth Quarter
($ in millions, except per share data)	2020		2019		2020		2019		2020		2019		2020		2019
Revenues	$	10,076	$	10,990	$	11,197	$	11,144	$	11,500	$	11,069	$	12,018	$	11,472
Net income (loss) applicable to common shareholders	513		1,261		1,224		821		1,126		889		2,598		1,707
Earnings per common share - Basic	1.62		3.79		3.90		2.47		3.62		2.71		8.54		5.32
Earnings per common share - Diluted	1.59		3.74		3.86		2.44		3.58		2.67		8.45		5.23