Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
INTEREST INCOME
Loans		$ 1,524	$ 1,576	$ 3,062	$ 3,052
Loans held for sale		8	17	22	30
Securities available for sale		259	194	491	388
Held-to-maturity securities		73	81	148	155
Trading account assets		16	15	30	27
Short-term investments		192	111	334	153
Other investments		16	16	33	29
Total interest income		2,088	2,010	4,120	3,834
INTEREST EXPENSE
Deposits		817	531	1,599	881
Federal funds purchased and securities sold under repurchase agreements		1	48	2	70
Bank notes and other short-term borrowings		51	104	97	182
Long-term debt		332	349	660	624
Total interest expense		1,201	1,032	2,358	1,757
NET INTEREST INCOME		887	978	1,762	2,077
Provision for credit losses		100	167	201	306
Net interest income after provision for credit losses		787	811	1,561	1,771
NONINTEREST INCOME
Trust and investment services income		139	126	275	254
Investment banking and debt placement fees		126	120	296	265
Cards and payments income		85	85	162	166
Service charges on deposit accounts		66	69	129	136
Corporate services income		68	86	137	162
Commercial mortgage servicing fees		61	50	117	96
Corporate-owned life insurance income		34	32	66	61
Consumer mortgage income		16	14	30	25
Operating lease income and other leasing gains		21	23	45	48
Other income		11	4	17	4
Total noninterest income		627	609	1,274	1,217
NONINTEREST EXPENSE
Personnel		636	622	1,310	1,323
Net occupancy		66	65	133	135
Computer processing		101	95	203	187
Business services and professional fees		37	41	78	86
Equipment		20	22	40	44
Operating lease expense		17	21	34	41
Marketing		21	29	40	50
Other expense		181	181	384	386
Total noninterest expense		1,079	1,076	2,222	2,252
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES		335	344	613	736
Income taxes		62	58	121	139
INCOME (LOSS) FROM CONTINUING OPERATIONS		273	286	492	597
Income (loss) from discontinued operations		1	1	1	2
NET INCOME (LOSS)		274	287	493	599
Less: Net income (loss) attributable to noncontrolling interests		0	0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO KEY		274	287	493	599
Income (loss) from continuing operations attributable to Key common shareholders		237	250	420	525
Net income (loss) attributable to Key common shareholders		$ 238	$ 251	$ 421	$ 527
Per Common Share:
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		$ 0.25	$ 0.27	$ 0.45	$ 0.57
Income (loss) from discontinued operations, net of taxes (in usd per share)		0	0	0	0
Net income (loss) attributable to Key common shareholders (in usd per share)	[1]	0.25	0.27	0.45	0.57
Per Common Share — assuming dilution:
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		0.25	0.27	0.45	0.56
Income (loss) from discontinued operations, net of taxes (in usd per share)		0	0	0	0
Net income (loss) attributable to Key common shareholders (in usd per share)	[1]	$ 0.25	$ 0.27	$ 0.45	$ 0.57
Weighted-average Common Shares outstanding (in shares)		931,726	926,741	930,776	926,807
Effect of Common Share options and other stock awards (in shares)		6,761	3,713	7,040	5,513
Weighted-average Common Shares and potential Common Shares outstanding (in shares)	[2]	938,487	930,454	937,816	932,320

[1] EPS may not foot due to rounding.

[2] Assumes conversion of Common Share options and other stock awards and/or convertible preferred stock, as applicable.