Line of Business Results (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Financial Information of Business Groups

Year ended December 31,	Key Community Bank									Key Corporate Bank
dollars in millions	2017			2016			2015			2017			2016			2015
SUMMARY OF OPERATIONS
Net interest income (TE)	$	2,643		$	1,953		$	1,487		$	1,190		$	1,049		$	886
Noninterest income	1,200			925			788			1,147			1,013			926
Total revenue (TE) (a)	3,843			2,878			2,275			2,337			2,062			1,812
Provision for credit losses	209			143			90			20			127			83
Depreciation and amortization expense	116			76			56			96			60			43
Other noninterest expense	2,486			2,077			1,723			1,161			1,071			945
Income (loss) from continuing operations before income taxes (TE)	1,032			582			406			1,060			804			741
Allocated income taxes (benefit) and TE adjustments	383			217			151			246			178			196
Income (loss) from continuing operations	649			365			255			814			626			545
Income (loss) from discontinued operations, net of taxes	—			—			—			—			—			—
Net income (loss)	649			365			255			814			626			545
Less: Net income (loss) attributable to noncontrolling interests	—			—			—			—			(2		)	1
Net income (loss) attributable to Key	$	649		$	365		$	255		$	814		$	628		$	544
AVERAGE BALANCES (b)
Loans and leases	$	47,383		$	37,620		$	30,834		$	37,732		$	31,929		$	25,865
Total assets (a)	51,433			40,300			32,948			44,521			37,801			31,541
Deposits	79,669			63,873			51,163			21,318			20,783			19,043
OTHER FINANCIAL DATA
Expenditures for additions to long-lived assets (a), (b)	$	2,438		$	1,478		$	75		$	559		$	340		$	16
Net loan charge-offs (b)	166			114			92			40			83			40
Return on average allocated equity (b)	13.59		%	10.62		%	9.42		%	28.69		%	26.80		%	28.91		%
Return on average allocated equity	13.59			10.62			9.42			28.69			26.80			28.91
Average full-time equivalent employees (c)	10,924			8,936			7,520			2,407			2,244			2,100

(a) Substantially all revenue generated by our major business segments is derived from clients that reside in the United States. Substantially all long-lived assets, including premises and equipment, capitalized software, and goodwill held by our major business segments, are located in the United States.

(b) From continuing operations.

(c) The number of average full-time equivalent employees was not adjusted for discontinued operations.

Other Segments									Total Segments									Reconciling Items									Key
2017			2016			2015			2017			2016			2015			2017			2016			2015			2017			2016			2015
$	(23	)	$	(45	)	$	(8	)	$	3,810		$	2,957		$	2,365		$	20		$	(4	)	$	11		$	3,830		$	2,953		$	2,376
151			151			183			2,498			2,089			1,897			(20		)	(18		)	(17		)	2,478			2,071			1,880
128			106			175			6,308			5,046			4,262			—			(22		)	(6		)	6,308			5,024			4,256
—			(4		)	(8		)	229			266			165			—			—			1			229			266			166
3			4			8			215			140			107			169			163			148			384			303			255
39			35			46			3,686			3,183			2,714			28			270			(129		)	3,714			3,453			2,585
86			71			129			2,178			1,457			1,276			(197		)	(455		)	(26		)	1,981			1,002			1,250
(42		)	(20		)	1			587			375			348			103			(162		)	(17		)	690			213			331
128			91			128			1,591			1,082			928			(300		)	(293		)	(9		)	1,291			789			919
—			—			—			—			—			—			7			1			1			7			1			1
128			91			128			1,591			1,082			928			(293		)	(292		)	(8		)	1,298			790			920
3			2			3			3			—			4			(1		)	(1		)	—			2			(1		)	4
$	125		$	89		$	125		$	1,588		$	1,082		$	924		$	(292	)	$	(291	)	$	(8	)	$	1,296		$	791		$	916
$	1,225		$	1,486		$	1,852		$	86,340		$	71,035		$	58,551		$	25		$	113		$	43		$	86,365		$	71,148		$	58,594
37,079			31,934			26,935			133,033			110,035			91,424			686			2,502			602			133,719			112,537			92,026
1,988			1,213			467			102,975			85,869			70,673			(29		)	483			(43		)	102,946			86,352			70,630
$	19		—			—			$	3,016		$	1,818		$	91		$	81		$	116		$	49		$	3,097		$	1,934		$	139
1			$	7		$	9		207			204			141			1			1			1			208			205			142
86.81		%	52.66		%	58.96		%	20.47		%	18.19		%	19.25		%	(4.00		)%	(4.36		)%	(.15		)%	8.47		%	6.25		%	8.61		%
86.81			52.66			58.96			20.47			18.19			19.25			(3.91		)	(4.34		)	(.14		)	8.51			6.25			8.62
2			5			14			13,333			11,185			9,634			5,082			4,515			3,849			18,415			15,700			13,483