Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Class A Common Stock	Class B Common Stock	Series A Preferred Stock	Series B Preferred Stock	Series C Preferred Stock	Preferred Stock	Preferred Stock Series B Preferred Stock	Preferred Stock Series C Preferred Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid in Capital	Retained Earnings	Retained Earnings Class A Common Stock	Retained Earnings Class B Common Stock	Retained Earnings Series A Preferred Stock	Retained Earnings Series B Preferred Stock	Retained Earnings Series C Preferred Stock	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	526												526
Other comprehensive loss, net of tax	(475)																		(475)
Stock based compensation	72											72
Cash dividends declared		$ (14)	$ (1)											$ (14)	$ (1)
Preferred stock dividends declared				$ (9)	$ (9)	$ (6)										$ (9)	$ (9)	$ (6)
Issued in CIT Merger:	5,279				334	207		$ 334	$ 207	6		5,273
Ending balance, shareholders' equity at Jun. 30, 2022	10,642						881			15	1	5,345	4,865						(465)
Beginning balance, shareholders' equity at Mar. 31, 2022	10,570						881			15	1	5,344	4,634						(305)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	255												255
Other comprehensive loss, net of tax	(160)																		(160)
Stock based compensation	1											1
Cash dividends declared		(7)	0											(7)	0
Preferred stock dividends declared				(5)	(9)	(3)										(5)	(9)	(3)
Ending balance, shareholders' equity at Jun. 30, 2022	10,642						881			15	1	5,345	4,865						(465)
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	10,200												10,200
Other comprehensive loss, net of tax	(37)																		(37)
Stock based compensation	(3)											(3)
Cash dividends declared		(20)	(2)											(20)	(2)
Preferred stock dividends declared				(9)	(14)	(6)										(9)	(14)	(6)
Ending balance, shareholders' equity at Jun. 30, 2023	19,771						881			14	1	4,106	15,541						(772)
Beginning balance, shareholders' equity at Mar. 31, 2023	19,216						881			14	1	4,104	14,885						(669)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	682												682
Other comprehensive loss, net of tax	(103)																		(103)
Stock based compensation	2											2
Cash dividends declared		$ (10)	$ (1)											$ (10)	$ (1)
Preferred stock dividends declared				$ (5)	$ (7)	$ (3)										$ (5)	$ (7)	$ (3)
Ending balance, shareholders' equity at Jun. 30, 2023	$ 19,771						$ 881			$ 14	$ 1	$ 4,106	$ 15,541						$ (772)