Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
INTEREST INCOME
Loans		$ 882	$ 927	$ 2,659	$ 2,933
Loans held for sale		13	18	35	58
Securities available for sale		135	115	398	365
Held-to-maturity securities		43	53	133	171
Trading account assets		4	3	14	16
Short-term investments		9	1	20	14
Other investments		1	2	5	3
Total interest income		1,087	1,119	3,264	3,560
INTEREST EXPENSE
Deposits		15	54	52	319
Federal funds purchased and securities sold under repurchase agreements		0	0	0	6
Bank notes and other short-term borrowings		2	1	6	11
Long-term debt		54	64	168	225
Total interest expense		71	119	226	561
NET INTEREST INCOME		1,016	1,000	3,038	2,999
Provision for credit losses		(107)	160	(422)	1,001
Net interest income after provision for credit losses		1,123	840	3,460	1,998
NONINTEREST INCOME
Trust and investment services income		129	128	395	384
Investment banking and debt placement fees		235	146	614	418
Service charges on deposit accounts		91	77	247	229
Operating lease income and other leasing gains		37	38	111	128
Corporate services income		69	51	188	165
Cards and payments income		111	114	329	271
Corporate-owned life insurance income		33	30	94	101
Consumer mortgage income		33	51	106	133
Commercial mortgage servicing fees		34	18	112	48
Other income	[1]	25	28	89	(27)
Total noninterest income		797	681	2,285	1,850
NONINTEREST EXPENSE
Personnel		640	588	1,887	1,675
Net occupancy		74	76	225	223
Computer processing		67	59	211	170
Business services and professional fees		56	49	157	142
Equipment		25	25	75	74
Operating lease expense		30	33	95	103
Marketing		32	22	89	67
Intangible asset amortization		15	15	44	50
Other expense		173	170	476	477
Total noninterest expense		1,112	1,037	3,259	2,981
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES		808	484	2,486	867
Income taxes		165	60	501	113
INCOME (LOSS) FROM CONTINUING OPERATIONS		643	424	1,985	754
Income (loss) from discontinued operations		2	4	11	7
NET INCOME (LOSS)		645	428	1,996	761
Less: Net income (loss) attributable to noncontrolling interests		0	0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO KEY		645	428	1,996	761
Income (loss) from continuing operations attributable to Key common shareholders		616	397	1,905	674
Net income (loss) attributable to Key common shareholders		$ 618	$ 401	$ 1,916	$ 681
Per Common Share:
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		$ 0.65	$ 0.41	$ 1.99	$ 0.70
Income (loss) from discontinued operations, net of taxes (in usd per share)		0	0	0.01	0.01
Net income (loss) attributable to Key common shareholders (in usd per share)	[2]	0.66	0.41	2.00	0.70
Per Common Share — assuming dilution:
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		0.65	0.41	1.98	0.69
Income (loss) from discontinued operations, net of taxes (in usd per share)		0	0	0.01	0.01
Net income (loss) attributable to Key common shareholders (in usd per share)	[2]	0.65	0.41	1.99	0.70
Cash dividends declared per common share (in usd per share)		$ 0.185	$ 0.185	$ 0.555	$ 0.555
Weighted-average common shares outstanding (000) (in shares)		942,446	967,804	955,069	967,632
Effect of common share options and other stock awards (in shares)		10,077	6,184	9,712	6,648
Weighted-average common shares and potential common shares outstanding (in shares)	[3]	952,523	973,988	964,781	974,280

[1] For the three and nine months ended September 30, 2021, net securities gains (losses) totaled less than $1 million. For the three months ended September 30, 2021 and September 30, 2020, we did not have any impairment losses related to securities. For the three months ended September 30, 2020, we had no net securities gains (losses). For the nine months ended September 30, 2020, net securities gains (losses) totaled $4 million.

[2] EPS may not foot due to rounding.

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