Earnings Per Common Share (EPS) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Basic and diluted:
Net income		$ 1,550	$ 1,634
Preferred dividends		(21)	(21)
Net Income Loss Available to Common Shareholders		1,529	1,613
Earnings allocated to participating share awards		(11)	(13)
Net Income Attributable to Common Shareholders		$ 1,518	$ 1,600
Denominator:
Basic		841	859
Add: Weighted-average stock options		2	2
Diluted		843	861
Earnings Per Common Share, Basic (Note 15) [Abstract]
Net income attributable to common shareholders	[1]	$ 1.81	$ 1.86
Earnings Per Common Share, Diluted (Note 15) [Abstract]
Net income attributable to common shareholders	[1]	$ 1.8	$ 1.86
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per Share, amount		900,000	600,000

[1] Represents net income less (i) earnings allocated to participating share awards of $ 11 million and $ 13 million for the three months ended March 31 , 2019 and 2018 , respectively, and (ii) dividends on preferred shares of $ 21 million for both the three months ended March 31 , 2019 and 2018 .