Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Class A Common Stock	Class B Common Stock	Series A	Series B	Series C	Preferred Stock	Preferred Stock Series B	Preferred Stock Series C	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid in Capital	Additional Paid in Capital Class A Common Stock	Retained Earnings	Retained Earnings Class A Common Stock	Retained Earnings Class B Common Stock	Retained Earnings Series A	Retained Earnings Series B	Retained Earnings Series C	Accumulated Other Comprehensive Loss
Beginning balance, shareholders' equity at Dec. 31, 2021	$ 4,738						$ 340			$ 9	$ 1	$ 0		$ 4,378						$ 10
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	841													841
Other comprehensive loss, net of tax	(739)																			(739)
Issued in CIT Merger:	5,279				$ 334	$ 207		$ 334	$ 207	6		5,273
Stock based compensation	74											74
Repurchased shares of Class A common stock		$ (842)								(1)			$ (841)
Cash dividends declared		(21)	$ (2)												$ (21)	$ (2)
Preferred stock dividends declared:				$ (14)	(14)	(8)											$ (14)	$ (14)	$ (8)
Ending balance, shareholders' equity at Sep. 30, 2022	9,833						881			14	1	4,506		5,160						(729)
Beginning balance, shareholders' equity at Jun. 30, 2022	10,642						881			15	1	5,345		4,865						(465)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	315													315
Other comprehensive loss, net of tax	(264)																			(264)
Stock based compensation	2											2
Repurchased shares of Class A common stock		(842)								(1)			$ (841)
Cash dividends declared		(7)	(1)												(7)	(1)
Preferred stock dividends declared:				(5)	(5)	(2)											(5)	(5)	(2)
Ending balance, shareholders' equity at Sep. 30, 2022	9,833						881			14	1	4,506		5,160						(729)
Beginning balance, shareholders' equity at Dec. 31, 2022	9,662						881			14	1	4,109		5,392						(735)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	10,952													10,952
Other comprehensive loss, net of tax	(145)																			(145)
Stock based compensation	(3)											(3)
Cash dividends declared		(31)	$ (2)												(31)	$ (2)
Preferred stock dividends declared:				(14)	(22)	(8)											(14)	(22)	(8)
Ending balance, shareholders' equity at Sep. 30, 2023	20,389						881			14	1	4,106		16,267						(880)
Beginning balance, shareholders' equity at Jun. 30, 2023	19,771						881			14	1	4,106		15,541						(772)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	752													752
Other comprehensive loss, net of tax	(108)																			(108)
Cash dividends declared		$ (10)													$ (10)
Preferred stock dividends declared:				$ (5)	$ (8)	$ (3)											$ (5)	$ (8)	$ (3)
Ending balance, shareholders' equity at Sep. 30, 2023	$ 20,389						$ 881			$ 14	$ 1	$ 4,106		$ 16,267						$ (880)