INVESTMENT SECURITIES - Gross Unrealized Losses and Fair Values of Securities (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Fair Value
Less than 12 months	$ 4,225	$ 4,990
12 months or more	8,950	2,547
Total	13,175	7,537
Gross Unrealized Losses
Less than 12 months	(389)	(94)
12 months or more	(1,517)	(67)
Total	(1,906)	(161)
U.S. Treasury and agency obligations
Fair Value
Less than 12 months	146	201
12 months or more	380	355
Total	526	556
Gross Unrealized Losses
Less than 12 months	(6)	(3)
12 months or more	(52)	(7)
Total	(58)	(10)
Mortgage-backed securities
Fair Value
Less than 12 months	1,114	2,082
12 months or more	1,802	556
Total	2,916	2,638
Gross Unrealized Losses
Less than 12 months	(131)	(49)
12 months or more	(419)	(20)
Total	(550)	(69)
Tax-exempt municipal securities
Fair Value
Less than 12 months	79	68
12 months or more	625	34
Total	704	102
Gross Unrealized Losses
Less than 12 months	(3)	(1)
12 months or more	(51)	(1)
Total	(54)	(2)
Residential
Fair Value
Less than 12 months	127	358
12 months or more	277	8
Total	404	366
Gross Unrealized Losses
Less than 12 months	(15)	(6)
12 months or more	(63)	0
Total	(78)	(6)
Commercial
Fair Value
Less than 12 months	252	295
12 months or more	1,156	400
Total	1,408	695
Gross Unrealized Losses
Less than 12 months	(13)	(4)
12 months or more	(141)	(7)
Total	(154)	(11)
Asset-backed securities
Fair Value
Less than 12 months	598	530
12 months or more	1,226	425
Total	1,824	955
Gross Unrealized Losses
Less than 12 months	(30)	(3)
12 months or more	(51)	(1)
Total	(81)	(4)
Corporate debt securities
Fair Value
Less than 12 months	1,909	1,456
12 months or more	3,484	769
Total	5,393	2,225
Gross Unrealized Losses
Less than 12 months	(191)	(28)
12 months or more	(740)	(31)
Total	$ (931)	$ (59)