KeyCorp (KEY) 10-Q 2 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018
Document And Entity Information [Abstract]
Entity Registrant Name	KEYCORP /NEW/
Trading Symbol	KEY
Entity Central Index Key	91,576
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,052,036,090

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
ASSETS
Cash and due from banks		$ 784	$ 671
Short-term investments		2,646	4,447
Trading account assets		833	836
Securities available for sale		17,367	18,139
Held-to-maturity securities (fair value: $11,735 and $11,565)		12,277	11,830
Other investments		709	726
Loans, net of unearned income of $684 and $736		88,222	86,405
Less: Allowance for loan and lease losses		(887)	(877)
Net loans		87,335	85,528
Loans held for sale	[1]	1,418	1,107
Premises and equipment		892	930
Operating lease assets		903	821
Goodwill		2,516	2,538
Other intangible assets		361	416
Corporate-owned life insurance		4,147	4,132
Accrued income and other assets		4,382	4,237
Discontinued assets		1,222	1,340
Total assets		137,792	137,698
Deposits in domestic offices:
NOW and money market deposit accounts		55,059	53,627
Savings deposits		6,199	6,296
Certificates of deposit ($100,000 or more)		7,547	6,849
Other time deposits		4,943	4,798
Total interest-bearing deposits		73,748	71,570
Noninterest-bearing deposits		30,800	33,665
Total deposits		104,548	105,235
Federal funds purchased and securities sold under repurchase agreements		1,667	377
Bank notes and other short-term borrowings		639	634
Accrued expense and other liabilities		1,983	2,094
Long-term debt		13,853	14,333
Total liabilities		122,690	122,673
EQUITY
Preferred stock		1,025	1,025
Common Shares, $1 par value; authorized 1,400,000,000 shares; issued 1,256,702,081, and 1,256,702,081 shares		1,257	1,257
Capital surplus		6,315	6,335
Retained earnings		10,970	10,335
Treasury stock, at cost (197,757,926 and 187,617,832 shares)		(3,382)	(3,150)
Accumulated other comprehensive income (loss)		(1,085)	(779)
Key shareholders’ equity		15,100	15,023
Noncontrolling interests		2	2
Total equity		15,102	15,025
Total liabilities and equity		$ 137,792	$ 137,698
[1]	Total loans held for sale include real estate — residential mortgage loans held for sale at fair value of $58 million at June 30, 2018 , and $71 million at December 31, 2017

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Held-to-maturity securities, fair value	$ 11,735,000,000	$ 11,565,000,000
Unearned income on loans	684,000,000	736,000,000
Loans held for sale	0	0
Aggregate amount of certificates of deposit, denominations	$ 100,000,000,000	$ 100,000,000,000
Common shares, par value (in usd per share)	$ 1	$ 1
Common shares, shares authorized (in shares)	1,400,000,000	1,400,000,000
Common shares, shares issued (in shares)	1,256,702,081	1,256,702,081
Treasury stock, shares (in shares)	197,757,926	187,617,832
Residential Mortgage [Member]
Loans held for sale	$ 58,000,000	$ 71,000,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
INTEREST INCOME
Loans		$ 1,000	$ 948	$ 1,940	$ 1,825
Loans held for sale		16	9	28	22
Securities available for sale		97	90	192	185
Held-to-maturity securities		72	55	141	106
Trading account assets		7	7	14	14
Short-term investments		8	5	16	8
Other investments		5	3	11	7
Total interest income		1,205	1,117	2,342	2,167
INTEREST EXPENSE
Deposits		112	66	203	124
Federal funds purchased and securities sold under repurchase agreements		5	0	9	1
Bank notes and other short-term borrowings		7	4	13	9
Long-term debt		102	74	194	142
Total interest expense		226	144	419	276
NET INTEREST INCOME		979	973	1,923	1,891
Provision for credit losses		64	66	125	129
Net interest income after provision for credit losses		915	907	1,798	1,762
NONINTEREST INCOME
Trust and investment services income		128	134	261	269
Investment banking and debt placement fees		155	135	298	262
Service charges on deposit accounts		91	90	180	177
Operating lease income and other leasing gains		(6)	30	26	53
Corporate services income		61	55	123	109
Cards and payments income		71	70	133	135
Corporate-owned life insurance income		32	33	64	63
Consumer mortgage income		7	6	14	12
Mortgage servicing fees		22	15	42	33
Other income	[1]	99	85	120	117
Total noninterest income		660	653	1,261	1,230
NONINTEREST EXPENSE
Personnel		586	553	1,180	1,110
Net occupancy		79	78	157	165
Computer processing		51	55	103	115
Business services and professional fees		51	45	92	91
Equipment		26	27	52	54
Operating lease expense		30	21	57	40
Marketing		26	30	51	51
FDIC assessment		21	21	42	41
Intangible asset amortization		25	22	54	44
OREO expense, net		0	3	2	5
Other expense		98	140	209	292
Total noninterest expense		993	995	1,999	2,008
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES		582	565	1,060	984
Income taxes		103	158	165	252
INCOME (LOSS) FROM CONTINUING OPERATIONS		479	407	895	732
Income (loss) from discontinued operations		3	5	5	5
NET INCOME (LOSS)		482	412	900	737
Less: Net income (loss) attributable to noncontrolling interests		0	0	0	1
NET INCOME (LOSS) ATTRIBUTABLE TO KEY		482	412	900	736
Income (loss) from continuing operations attributable to Key common shareholders		464	393	866	689
Net income (loss) attributable to Key common shareholders		$ 467	$ 398	$ 871	$ 694
Per Common Share:
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		$ 0.44	$ 0.36	$ 0.82	$ 0.64
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)	[2]	0.44	0.37	0.82	0.64
Per Common Share — assuming dilution:
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		0.44	0.36	0.81	0.63
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)	[2]	0.44	0.36	0.81	0.63
Cash dividends declared per common share (in usd per share)		$ 0.12	$ 0.095	$ 0.225	$ 0.180
Weighted-average common shares outstanding (in shares)		1,052,652	1,076,203	1,054,378	1,083,486
Effect of common share options and other stock awards (in shares)		13,141	16,836	14,561	15,808
Weighted-average common shares and potential common shares outstanding (in shares)	[3]	1,065,793	1,093,039	1,068,939	1,099,294
[1]	For the three months ended June 30, 2018 , net securities gains totaled less than $1 million. For the three months ended June 30, 2017 , net securities gains totaled $1 million. For the three months ended June 30, 2018 , and June 30, 2017
[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.

Consolidated Statements of Inc5

Consolidated Statements of Income (Parenthetical) - USD ($)	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Net securities gains (losses) (less than)	$ 1,000,000	$ 1,000,000
Impaired losses related to securities	$ 0	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 482	$ 412	$ 900	$ 737
Other comprehensive income (loss), net of tax:
Net unrealized gains (losses) on securities available for sale, net of income taxes of ($20), $20, ($67), and $24	(66)	34	(216)	40
Net unrealized gains (losses) on derivative financial instruments, net of income taxes of ($4), $4, ($24), and ($11)	(17)	7	(80)	(17)
Foreign currency translation adjustments, net of income taxes of $3, $3, $3, and $4	(14)	6	(16)	7
Net pension and postretirement benefit costs, net of income taxes of $1, $1, $2, and $3	3	1	6	5
Total other comprehensive income (loss), net of tax	(94)	48	(306)	35
Comprehensive income (loss)	388	460	594	772
Less: Comprehensive income attributable to noncontrolling interests	0	0	0	1
Comprehensive income (loss) attributable to Key	$ 388	$ 460	$ 594	$ 771

Consolidated Statements of Com7

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Income taxes effect on net unrealized (losses) gains on securities available for sale	$ (20)	$ 20	$ (67)	$ 24
Income taxes effect on net unrealized gains (losses) on derivative financial instruments	(4)	4	(24)	(11)
Income taxes effect on foreign currency translation adjustments	3	3	3	4
Income taxes effect on net pension and postretirement benefit costs	$ 1	$ 1	$ 2	$ 3

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Millions		Total	Series D Preferred Stock [Member]	Series E Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Retained Earnings [Member]Series A Preferred Stock [Member]	Retained Earnings [Member]Series C Preferred Stock [Member]	Retained Earnings [Member]Series D Preferred Stock [Member]	Retained Earnings [Member]Series E Preferred Stock [Member]	Treasury Stock, at Cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Beginning Balance, Preferred Shares at Dec. 31, 2016					17,421,000
Beginning Balance, Common Shares at Dec. 31, 2016						1,079,314,000
Beginning Balance at Dec. 31, 2016					$ 1,665	$ 1,257	$ 6,385	$ 9,378					$ (2,904)	$ (541)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		$ 737						736							1
Other comprehensive income (loss)		35												35
Deferred compensation							7
Cash dividends declared on common shares								(194)
Cash dividends declared on preferred stock									$ (6)	$ (7)	$ (13)	$ (16)
Open market common share repurchases (in shares)						(10,602,000)
Open market Common Share repurchases													(196)
Employee equity compensation program common share repurchase (in shares)						(3,143,000)
Employee equity compensation program Common Share repurchases													(59)
Series A Preferred Stock exchanged for common shares (in shares)					2,900,000	20,568,000
Series A Preferred Stock exchanged for common shares					$ (290)		(49)						338
Redemption of Series C Preferred Stock (in shares)					(14,000,000)
Redemption of Series C Preferred Stock		350			$ 350
Common shares reissued (returned) for stock options and other employee benefit plans, shares						6,602,000
Series A Preferred Stock exchanged for Common Shares							(33)						110
Net contribution from (distribution to) noncontrolling interests															1
Ending Balance, Preferred Shares at Jun. 30, 2017					521,000
Ending Balance, Common Shares at Jun. 30, 2017						1,092,739,000
Ending Balance at Jun. 30, 2017					$ 1,025	$ 1,257	6,310	9,878					(2,711)	(506)	2
Beginning Balance at Mar. 31, 2017														(554)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		412
Other comprehensive income (loss)		48
Ending Balance, Preferred Shares at Jun. 30, 2017					521,000
Ending Balance, Common Shares at Jun. 30, 2017						1,092,739,000
Ending Balance at Jun. 30, 2017					$ 1,025	$ 1,257	6,310	9,878					(2,711)	(506)	2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect from changes in accounting principle	[1]							(2)
Beginning Balance, Preferred Shares at Dec. 31, 2017			21,000	500,000	521,000
Beginning Balance, Common Shares at Dec. 31, 2017						1,069,084,000
Beginning Balance at Dec. 31, 2017		15,025			$ 1,025	$ 1,257	6,335	10,335					(3,150)	(779)	2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other reclassification of AOCI		(5)						5
Net income (loss)		900						900							0
Other comprehensive income (loss)		(306)												(306)
Deferred compensation							12
Cash dividends declared on common shares								(239)
Cash dividends declared on preferred stock											$ (13)	$ (16)
Open market common share repurchases (in shares)						(13,438,000)
Open market Common Share repurchases													(279)
Employee equity compensation program common share repurchase (in shares)						(2,221,000)
Employee equity compensation program Common Share repurchases													(46)
Redemption of Series C Preferred Stock		0
Common shares reissued (returned) for stock options and other employee benefit plans, shares						5,519,000
Series A Preferred Stock exchanged for Common Shares							(32)						93
Ending Balance, Preferred Shares at Jun. 30, 2018			21,000	500,000	521,000
Ending Balance, Common Shares at Jun. 30, 2018						1,058,944,000
Ending Balance at Jun. 30, 2018		15,102			$ 1,025	$ 1,257	6,315	10,970					(3,382)	(1,085)	2
Beginning Balance at Mar. 31, 2018														(991)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other reclassification of AOCI		(5)
Net income (loss)		482
Other comprehensive income (loss)		(94)
Ending Balance, Preferred Shares at Jun. 30, 2018			21,000	500,000	521,000
Ending Balance, Common Shares at Jun. 30, 2018						1,058,944,000
Ending Balance at Jun. 30, 2018		$ 15,102			$ 1,025	$ 1,257	$ 6,315	$ 10,970					$ (3,382)	$ (1,085)	$ 2
[1]	Includes the impact of implementing ASU 2014-09, ASU 2016-01, and ASU 2017-12.

Consolidated Statements of Cha9

Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash dividends declared on common shares (in usd per share)	$ 0.225	$ 0.180
Series A Preferred Stock [Member]
Cash dividends declared on Preferred Stock (in usd per share)		1.9375
Series C Preferred Stock [Member]
Cash dividends declared on Preferred Stock (in usd per share)		0.539063
Series D Preferred Stock [Member]
Cash dividends declared on Preferred Stock (in usd per share)	25	25
Series E Preferred Stock [Member]
Cash dividends declared on Preferred Stock (in usd per share)	$ 0.765626	$ 0.778386

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
OPERATING ACTIVITIES
Net income (loss)	$ 900	$ 737
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Provision for credit losses	125	129
Depreciation and amortization expense, net	195	198
Accretion of acquired loans	22	133
Increase in cash surrender value of corporate-owned life insurance	(56)	(56)
Stock-based compensation expense	53	51
FDIC reimbursement (payments), net of FDIC expense	2	(2)
Deferred income taxes (benefit)	17	212
Proceeds from sales of loans held for sale	5,703	4,881
Originations of loans held for sale, net of repayments	(5,944)	(5,435)
Net losses (gains) on sales of loans held for sale	(89)	(74)
Net losses (gains) and writedown on OREO	2	2
Net losses (gains) on leased equipment	(37)	(9)
Net securities losses (gains)	0	(1)
Net losses (gains) on sales of fixed assets	4	14
Net decrease (increase) in trading account assets	3	(214)
Gain on sale of Key Insurance & Benefits, Inc.	(78)	0
Other operating activities, net	(414)	(1,155)
NET CASH PROVIDED BY (USED IN) OPERATING ACTIVITIES	408	(589)
INVESTING ACTIVITIES
Cash received (used) in acquisitions, net of cash acquired	0	(74)
Proceeds from sale of Key Insurance & Benefits Services, Inc.	119	0
Net decrease (increase) in short-term investments, excluding acquisitions	1,801	253
Purchases of securities available for sale	(1,167)	(723)
Proceeds from sales of securities available for sale	0	915
Proceeds from prepayments and maturities of securities available for sale	1,640	2,036
Proceeds from prepayments and maturities of held-to-maturity securities	797	890
Purchases of held-to-maturity securities	(1,242)	(1,297)
Purchases of other investments	(6)	(69)
Proceeds from sales of other investments	22	70
Proceeds from prepayments and maturities of other investments	2	2
Net decrease (increase) in loans, excluding acquisitions, sales and transfers	(2,044)	(832)
Proceeds from sales of portfolio loans	99	77
Proceeds from corporate-owned life insurance	41	25
Purchases of premises, equipment, and software	(36)	(24)
Proceeds from sales of premises and equipment	1	0
Proceeds from sales of OREO	14	19
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	41	1,268
FINANCING ACTIVITIES
Net increase (decrease) in deposits, excluding acquisitions	(687)	(1,266)
Net increase (decrease) in short-term borrowings	1,295	394
Net proceeds from issuance of long-term debt	1,758	950
Payments on long-term debt	(2,123)	(17)
Open market Common Share repurchases	(279)	(196)
Employee equity compensation program Common Share repurchases	(46)	(59)
Redemption of Preferred Stock Series C	0	(350)
Net proceeds from reissuance of Common Shares	14	25
Cash dividends paid	(268)	(236)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	(336)	(755)
NET INCREASE (DECREASE) IN CASH AND DUE FROM BANKS	113	(76)
CASH AND DUE FROM BANKS AT BEGINNING OF PERIOD	671	677
CASH AND DUE FROM BANKS AT END OF PERIOD	784	601
Additional disclosures relative to cash flows:
Interest paid	389	281
Income taxes paid (refunded)	14	60
Noncash items:
Reduction of secured borrowing and related collateral	15	21
Loans transferred to portfolio from held for sale	21	19
Loans transferred to (from) held for sale from portfolio	(3)	29
Loans transferred to OREO	$ 9	$ 19

Basis of Presentation and Accou

Basis of Presentation and Accounting Policies	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Accounting Policies	1. Basis of Presentation and Accounting Policies The consolidated financial statements include the accounts of KeyCorp and its subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. Some previously reported amounts have been reclassified to conform to current reporting practices. The consolidated financial statements include any voting rights entities in which we have a controlling financial interest. In accordance with the applicable accounting guidance for consolidations, we consolidate a VIE if we have: (i) a variable interest in the entity; (ii) the power to direct activities of the VIE that most significantly affect the entity’s economic performance; and (iii) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE (i.e., we are considered to be the primary beneficiary). Variable interests can include equity interests, subordinated debt, derivative contracts, leases, service agreements, guarantees, standby letters of credit, loan commitments, and other contracts, agreements, and financial instruments. See Note 9 (“ Variable Interest Entities ”) for information on our involvement with VIEs. We use the equity method to account for unconsolidated investments in voting rights entities or VIEs if we have significant influence over the entity’s operating and financing decisions (usually defined as a voting or economic interest of 20% to 50% , but not controlling). Unconsolidated investments in voting rights entities or VIEs in which we have a voting or economic interest of less than 20% are carried at the cost measurement alternative or at fair value. Investments held by our registered broker-dealer and investment company subsidiaries (principal investing entities and Real Estate Capital line of business) are carried at fair value. We believe that the unaudited consolidated interim financial statements reflect all adjustments of a normal recurring nature and disclosures that are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim period are not necessarily indicative of the results of operations to be expected for the full year. The interim financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in our 2017 Form 10-K. In preparing these financial statements, subsequent events were evaluated through the time the financial statements were issued. Financial statements are considered issued when they are widely distributed to all shareholders and other financial statement users or filed with the SEC. Accounting Guidance Adopted in 2018 Standard Date of Adoption Description Effect on Financial Statements or Other Significant Matters ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ASU 2015-14, Deferral of Effective Date ASU 2016-08, Principal versus Agent Considerations ASU 2016-10, Identifying Performance Obligations and Licensing ASU 2016-11, Rescission of SEC Guidance because of Accounting Standard Updates 2014-09 and 2014-16 pursuant to Staff Announcements at the March 3, 2016 EITF Meeting ASU 2016-12, Narrow-scope Improvements and Practical Expedients ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers January 1, 2018 These ASUs supersede the revenue recognition guidance in ASC 605, Revenue Recognition, and most industry-specific guidance. The core principle of these ASUs is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. These ASUs can be implemented using a retrospective method, or a cumulative-effect approach to new contracts and existing contracts with performance obligations as of the effective date. On January 1, 2018, we adopted ASC 606, Revenue from Contracts with Customers (ASC 606), using the modified retrospective method for those contracts which were not completed as of that date. Results for reporting periods beginning January 1, 2018, are presented under ASC 606. As allowed under the new guidance, the comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. As a result of adopting ASC 606, we changed the timing of recognition for revenues related to insurance commissions, securities underwriting, and deposit account maintenance fees, however, those changes did not have a material impact on our consolidated financial statements, results of operations, equity, or cash flows as of the adoption date or for the six months ended June 30, 2018. The presentation of underwriting costs and reimbursed out-of-pocket expenses related to underwriting and M&A advisory services was changed from net to gross within the income statement as Key acts as the principal in the transactions. Securities underwriting revenue is recorded within "investment banking and debt placement fees" and underwriting costs and reimbursed out-of-pocket expenses within "other expense" on the income statement. Additionally, because Key acts as an agent, certain credit and debit card reward costs and certain card network costs were changed from a gross presentation to net within "cards and payment income" on the income statement. Credit and debit card reward costs and card network costs were recorded as "other expense" on the income statement in prior periods. These changes in presentation did not have a material impact on our consolidated financial statements for the six months ended June 30, 2018. ASC 606 requires quantitative disclosure of the allocation of the transaction price to the remaining performance obligations when those amounts are expected to be recognized as revenue. However, the standard provides exemptions from this disclosure for (i) contracts with an original expected length of one year or less and (ii) contracts for which we recognize revenue at the amount to which we have the right to invoice for services provided. Most of our revenue subject to ASC 606 fits into one of these exemptions, or is immaterial. We elected to use the optional exemption to not disclose the aggregate amount of the transaction price to remaining performance obligations. ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities January 1, 2018 The ASU amends ASC Topic 815, Derivatives and Hedging , to simplify the requirements for hedge accounting and facilitate financial reporting that more closely aligns with an entity’s risk management activities. Key amendments include: eliminating the requirement to separately measure and report hedge ineffectiveness, requiring changes in the value of the hedging instrument to be presented in the same income statement line as the earnings effect of the hedged item, and the ability to measure the hedged item based on the benchmark interest rate component of the total contractual coupon for fair value hedges. Additional disclosures are also required for reporting periods subsequent to the date of adoption. The guidance should be implemented on a modified retrospective basis to existing hedge relationships as of the adoption date. On January 1, 2018, we adopted this ASU using a modified retrospective basis. Accordingly, our financial statements for the quarter ended June 30, 2018, include an immaterial cumulative-effect adjustment to decrease opening retained earnings to reflect the application of the new guidance as of January 1, 2018. The primary impact to Key at adoption was the election to measure the change in fair value of hedged items in fair value hedges on the basis of the benchmark interest rate component of contractual coupon cash flows. This change has resulted in a reduction of hedge ineffectiveness for impacted fair value hedges. Instruments designated as hedges are recorded at fair value and included in “accrued income and other assets” or “accrued expense and other liabilities” on the balance sheet. Under the revised guidance, the change in the fair value of an instrument designated as a fair value hedge is recorded in earnings at the same time and in the same income statement line as the offsetting change in the fair value of the hedged item. For cash flow hedges, the change in the fair value of an instrument designated as a cash flow hedge is initially recorded in AOCI on the balance sheet. This amount is subsequently reclassified into income when the hedged transaction affects earnings and is presented in the same income statement line item as the earnings effect of the hedged item. Standard Date of Adoption Description Effect on Financial Statements or Other Significant Matters ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities January 1, 2018 The ASU amends ASC Topic 825, Financial Instruments-Overall, and requires equity investments, except those accounted for under the equity method of accounting or consolidated, to be measured at fair value with changes recognized in net income. If there is no readily determinable fair value, the guidance allows entities the ability to measure investments at cost less impairment, whereby impairment is based on a qualitative assessment. The guidance eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost and changes the presentation of financial assets and financial liabilities on the balance sheet or in the footnotes. If an entity has elected the fair value option to measure liabilities, the new accounting guidance requires the portion of the change in the fair value of a liability resulting from credit risk to be presented in OCI. With the exception of disclosure requirements that will be adopted prospectively, the ASU must be adopted on a modified retrospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments January 1, 2018 The ASU amends ASC Topic 230, Statement of Cash Flows , and clarifies how cash receipts and cash payments in certain transactions should be presented and classified in the statement of cash flows. These specific transactions include, but are not limited to, debt prepayment or extinguishment costs, contingent considerations made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, and distributions from equity method investees. This guidance also clarifies that in instances of cash flows with multiple aspects that cannot be separately identified, classification should be based on the activity that is likely to be the predominant source of or use of cash flow. The guidance should be implemented using a retrospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-01, Clarifying the Definition of a Business January 1, 2018 The ASU amends Topic 805, Business Combinations, and clarifies the definition of a business and removes the requirement for a market participant to consider whether it could replace missing elements in an integrated set of assets and activities. The guidance states that if substantially all of the fair value of the assets acquired or disposed of is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The guidance should be implemented using a prospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-05, Other Income- Gains and Losses from the Derecognition of Nonfinancial Assets January 1, 2018 The ASU amends ASC Topic 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets to clarify the scope of the Topic by clarifying the definition of the term "in substance nonfinancial asset" and also adding guidance for partial sales of nonfinancial assets. Under the new guidance, an entity will derecognize a nonfinancial asset when it does not have or ceases to have a controlling interest in the legal entity that holds the asset and when control of the asset has transferred in accordance with ASC 606. The ASU can be adopted on a retrospective or modified retrospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost January 1, 2018 The ASU amends ASC Topic 715, Compensation - Retirement Benefits , and requires service costs to be included in the same line item as certain other compensation costs related to services rendered by employees. We record compensation costs under personnel expense on the income statement. Other elements of net benefit cost should be presented separately. The guidance should be implemented on a retrospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-09, Scope of Modification Accounting January 1, 2018 The ASU amends ASC Topic 718, Compensation - Stock Compensation , and clarifies when changes to terms and conditions for share-based payment awards should be accounted for as modifications. Under the new guidance, entities should apply the modification guidance unless the fair value of the modified award is the same as the fair value of the original award immediately before modification, the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before modification, and the classification of the modified award (as equity or liability instrument) is the same as the classification of the original award immediately before modification. The guidance should be applied on a prospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations.

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings Per Common Share	2. Earnings Per Common Share Basic earnings per share is the amount of earnings (adjusted for dividends declared on our preferred stock) available to each Common Share outstanding during the reporting periods. Diluted earnings per share is the amount of earnings available to each Common Share outstanding during the reporting periods adjusted to include the effects of potentially dilutive Common Shares. Potentially dilutive Common Shares include stock options and other stock-based awards. Potentially dilutive Common Shares are excluded from the computation of diluted earnings per share in the periods where the effect would be antidilutive. Our basic and diluted earnings per Common Share are calculated as follows: Three months ended June 30, Six months ended June 30, dollars in millions, except per share amounts 2018 2017 2018 2017 EARNINGS Income (loss) from continuing operations $ 479 $ 407 $ 895 $ 732 Less: Net income (loss) attributable to noncontrolling interests — — — 1 Income (loss) from continuing operations attributable to Key 479 407 895 731 Less: Dividends on Preferred Stock 15 14 29 42 Income (loss) from continuing operations attributable to Key common shareholders 464 393 866 689 Income (loss) from discontinued operations, net of taxes 3 5 5 5 Net income (loss) attributable to Key common shareholders $ 467 $ 398 $ 871 $ 694 WEIGHTED-AVERAGE COMMON SHARES Weighted-average common shares outstanding (000) 1,052,652 1,076,203 1,054,378 1,083,486 Effect of Common Share options and other stock awards 13,141 16,836 14,561 15,808 Weighted-average Common Shares and potential Common Shares outstanding (000) (a) 1,065,793 1,093,039 1,068,939 1,099,294 EARNINGS PER COMMON SHARE Income (loss) from continuing operations attributable to Key common shareholders $ .44 $ .36 $ .82 $ .64 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) attributable to Key common shareholders (b) .44 .37 .82 .64 Income (loss) from continuing operations attributable to Key common shareholders — assuming dilution $ .44 $ .36 $ .81 $ .63 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) attributable to Key common shareholders — assuming dilution (b) .44 .36 .81 .63 (a) Assumes conversion of Common Share options and other stock awards and/or convertible preferred stock, as applicable. (b)

Loan Portfolio

Loan Portfolio	6 Months Ended
	Jun. 30, 2018
Loans Receivables [Abstract]
Loan Portfolio	3. Loan Portfolio in millions June 30, 2018 December 31, 2017 Commercial and industrial (a) $ 44,569 $ 41,859 Commercial real estate: Commercial mortgage 14,162 14,088 Construction 1,736 1,960 Total commercial real estate loans 15,898 16,048 Commercial lease financing (b) 4,509 4,826 Total commercial loans 64,976 62,733 Residential — prime loans: Real estate — residential mortgage 5,452 5,483 Home equity loans 11,519 12,028 Total residential — prime loans 16,971 17,511 Consumer direct loans 1,785 1,794 Credit cards 1,094 1,106 Consumer indirect loans 3,396 3,261 Total consumer loans 23,246 23,672 Total loans (c) $ 88,222 $ 86,405 (a) Loan balances include $128 million and $119 million of commercial credit card balances at June 30, 2018 , and December 31, 2017 , respectively. (b) Commercial lease financing includes receivables held as collateral for a secured borrowing of $16 million and $24 million at June 30, 2018 , and December 31, 2017 , respectively. Principal reductions are based on the cash payments received from these related receivables. Additional information pertaining to this secured borrowing is included in Note 20 (“ Long-Term Debt ”) beginning on page 174 of our 2017 Form 10-K. (c) Total loans exclude loans of $1.2 billion at June 30, 2018 , and $1.3 billion at December 31, 2017

Asset Quality

Asset Quality	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Asset Quality	4. Asset Quality We assess the credit quality of the loan portfolio by monitoring net credit losses, levels of nonperforming assets, delinquencies, and credit quality ratings as defined by management. Credit Quality Indicators The prevalent risk characteristic for both commercial and consumer loans is the risk of loss arising from an obligor’s inability or failure to meet contractual payment or performance terms. Evaluation of this risk is stratified and monitored by the loan risk rating grades assigned for the commercial loan portfolios and the refreshed FICO score assigned for the consumer loan portfolios. Most extensions of credit are subject to loan grading or scoring. Loan grades are assigned at the time of origination, verified by credit risk management, and periodically re-evaluated thereafter. This risk rating methodology blends our judgment with quantitative modeling. Commercial loans generally are assigned two internal risk ratings. The first rating reflects the probability that the borrower will default on an obligation; the second rating reflects expected recovery rates on the credit facility. Default probability is determined based on, among other factors, the financial strength of the borrower, an assessment of the borrower’s management, the borrower’s competitive position within its industry sector, and our view of industry risk in the context of the general economic outlook. Types of exposure, transaction structure, and collateral, including credit risk mitigants, affect the expected recovery assessment. Commercial Credit Exposure — Excluding PCI Credit Risk Profile by Creditworthiness Category (a), (b) Commercial and industrial RE — Commercial RE — Construction Commercial lease Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, RATING 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 Pass $ 42,517 $ 39,833 $ 13,368 $ 13,328 $ 1,682 $ 1,894 $ 4,420 $ 4,730 $ 61,987 $ 59,785 Criticized (Accruing) 1,817 1,790 540 482 49 38 68 90 2,474 2,400 Criticized (Nonaccruing) 178 153 42 30 2 2 21 6 243 191 Total $ 44,512 $ 41,776 $ 13,950 $ 13,840 $ 1,733 $ 1,934 $ 4,509 $ 4,826 $ 64,704 $ 62,376 (a) Credit quality indicators are updated on an ongoing basis and reflect credit quality information as of the dates indicated. (b) The term criticized refers to those loans that are internally classified by Key as special mention or worse, which are asset quality categories defined by regulatory authorities. These assets have an elevated level of risk and may have a high probability of default or total loss. Pass rated refers to all loans not classified as criticized. Consumer Credit Exposure — Excluding PCI Non-PCI Loans by Refreshed FICO Score (a) Residential — Prime Consumer direct loans Credit cards Consumer indirect loans Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, FICO SCORE 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 750 and above $ 10,004 $ 10,226 $ 517 $ 519 $ 482 $ 477 $ 1,493 $ 1,472 $ 12,496 $ 12,694 660 to 749 4,871 5,181 673 690 502 508 1,181 1,184 7,227 7,563 Less than 660 1,564 1,519 211 225 110 121 503 529 2,388 2,394 No Score 179 208 380 356 — — 219 76 778 640 Total $ 16,618 $ 17,134 $ 1,781 $ 1,790 $ 1,094 $ 1,106 $ 3,396 $ 3,261 $ 22,889 $ 23,291 (a) Borrower FICO scores provide information about the credit quality of our consumer loan portfolio as they provide an indication as to the likelihood that a debtor will repay its debts. The scores are obtained from a nationally recognized consumer rating agency and are presented in the above table at the dates indicated. Commercial Credit Exposure — PCI Credit Risk Profile by Creditworthiness Category (a), (b) Commercial and Industrial RE — Commercial RE — Construction Commercial Lease Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, RATING 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 Pass $ 25 $ 41 $ 140 $ 153 $ 3 $ 26 — — $ 168 $ 220 Criticized 32 42 72 95 — — — — 104 137 Total $ 57 $ 83 $ 212 $ 248 $ 3 $ 26 — — $ 272 $ 357 (a) Credit quality indicators are updated on an ongoing basis and reflect credit quality information as of the dates indicated. (b) The term “criticized” refers to those loans that are internally classified by Key as special mention or worse, which are asset quality categories defined by regulatory authorities. These assets have an elevated level of risk and may have a high probability of default or total loss. Pass rated refers to all loans not classified as criticized. Consumer Credit Exposure — PCI PCI Loans by Refreshed FICO Score (a) Residential — Prime Consumer direct loans Credit cards Consumer indirect loans Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, FICO SCORE 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 750 and above $ 142 $ 149 $ 1 — — — — — $ 143 $ 149 660 to 749 102 117 1 $ 2 — — — — 103 119 Less than 660 107 105 2 2 — — — — 109 107 No Score 2 6 — — — — — — 2 6 Total $ 353 $ 377 $ 4 $ 4 — — — — $ 357 $ 381 (a) Borrower FICO scores provide information about the credit quality of our consumer loan portfolio as they provide an indication as to the likelihood that a debtor will repay its debts. The scores are obtained from a nationally recognized consumer rating agency and are presented in the above table at the dates indicated. Nonperforming and Past Due Loans Our policies for determining past due loans, placing loans on nonaccrual, applying payments on nonaccrual loans, and resuming accrual of interest for our commercial and consumer loan portfolios are disclosed in Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Nonperforming Loans” beginning on page 101 of our 2017 Form 10-K. The following aging analysis of past due and current loans as of June 30, 2018 , and December 31, 2017 , provides further information regarding Key’s credit exposure. Aging Analysis of Loan Portfolio (a) June 30, 2018 Current 30-59 Days Past Due (b) 60-89 Days Past Due (b) 90 and Greater Days Past Due (b) Non-performing Loans Total Past Due and Non-performing Loans Purchased Credit Impaired Total Loans (c), (d) in millions LOAN TYPE Commercial and industrial $ 44,137 $ 129 $ 40 $ 28 $ 178 $ 375 $ 57 $ 44,569 Commercial real estate: Commercial mortgage 13,740 38 100 30 42 210 212 14,162 Construction 1,719 2 1 9 2 14 3 1,736 Total commercial real estate loans 15,459 40 101 39 44 224 215 15,898 Commercial lease financing 4,467 15 2 4 21 42 — 4,509 Total commercial loans $ 64,063 $ 184 $ 143 $ 71 $ 243 $ 641 $ 272 $ 64,976 Real estate — residential mortgage $ 5,039 $ 11 $ 8 $ 6 $ 55 $ 80 $ 333 $ 5,452 Home equity loans 11,235 25 9 8 222 264 20 11,519 Consumer direct loans 1,759 8 4 6 4 22 4 1,785 Credit cards 1,073 5 4 10 2 21 — 1,094 Consumer indirect loans 3,347 23 5 2 19 49 — 3,396 Total consumer loans $ 22,453 $ 72 $ 30 $ 32 $ 302 $ 436 $ 357 $ 23,246 Total loans $ 86,516 $ 256 $ 173 $ 103 $ 545 $ 1,077 $ 629 $ 88,222 (a) Amounts in table represent recorded investment and exclude loans held for sale. Recorded investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. (b) Past due loan amounts exclude PCI, even if contractually past due (or if we do not expect to collect principal or interest in full based on the original contractual terms), as we are currently accreting income over the remaining term of the loans. (c) Net of unearned income, net deferred loan fees and costs, and unamortized discounts and premiums. (d) Future accretable yield related to PCI loans is not included in the analysis of the loan portfolio. December 31, 2017 Current 30-59 Days Past Due (b) 60-89 Days Past Due (b) 90 and Greater Days Past Due (b) Non-performing Loans Total Past Due and Non-performing Loans Purchased Credit Impaired Total Loans (c), (d) in millions LOAN TYPE Commercial and industrial $ 41,444 $ 111 $ 34 $ 34 $ 153 $ 332 83 $ 41,859 Commercial real estate: Commercial mortgage 13,750 26 13 21 30 90 248 14,088 Construction 1,919 4 9 — 2 15 26 1,960 Total commercial real estate loans 15,669 30 22 21 32 105 274 16,048 Commercial lease financing 4,791 23 4 2 6 35 — 4,826 Total commercial loans $ 61,904 $ 164 $ 60 $ 57 $ 191 $ 472 357 $ 62,733 Real estate — residential mortgage $ 5,043 $ 16 $ 7 $ 4 $ 58 $ 85 $ 355 $ 5,483 Home equity loans 11,721 32 15 9 229 285 22 12,028 Consumer direct loans 1,768 9 4 5 4 22 4 1,794 Credit cards 1,081 7 5 11 2 25 — 1,106 Consumer indirect loans 3,199 33 7 3 19 62 — 3,261 Total consumer loans $ 22,812 $ 97 $ 38 $ 32 $ 312 $ 479 $ 381 $ 23,672 Total loans $ 84,716 $ 261 $ 98 $ 89 $ 503 $ 951 $ 738 $ 86,405 (a) Amounts in table represent recorded investment and exclude loans held for sale. Recorded investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. (b) Past due loan amounts exclude PCI, even if contractually past due (or if we do not expect to collect principal or interest in full based on the original contractual terms), as we are currently accreting income over the remaining term of the loans. (c) Net of unearned income, net deferred loan fees and costs, and unamortized discounts and premiums. (d) Future accretable yield related to purchased credit impaired loans is not included in the analysis of the loan portfolio. At June 30, 2018 , the approximate carrying amount of our commercial nonperforming loans outstanding represented 71% of their original contractual amount owed, total nonperforming loans outstanding represented 79% of their original contractual amount owed, and nonperforming assets in total were carried at 79% of their original contractual amount owed. Nonperforming loans and loans held for sale reduced expected interest income by $7 million and $14 million for the three and six months ended June 30, 2018 , respectively, and $6 million and $12 million for the three and six months ended June 30, 2017 , respectively. The following tables set forth a further breakdown of individually impaired loans as of June 30, 2018 , and December 31, 2017 : June 30, 2018 December 31, 2017 Recorded Investment (a) Unpaid Principal Balance (b) Specific Allowance Recorded Investment (a) Unpaid Principal Balance (b) Specific Allowance in millions With no related allowance recorded: Commercial and industrial $ 123 $ 154 — $ 126 $ 153 — Commercial real estate: Commercial mortgage 20 25 — 12 18 — Total commercial real estate loans 20 25 — 12 18 — Total commercial loans 143 179 — 138 171 — Real estate — residential mortgage 16 24 — 17 17 — Home equity loans 51 59 — 56 56 — Consumer indirect loans 2 4 — 2 2 — Total consumer loans 69 87 — 75 75 — Total loans with no related allowance recorded 212 266 — 213 246 — With an allowance recorded: Commercial and industrial 64 94 $ 7 10 28 $ 6 Total commercial loans 64 94 7 10 28 6 Real estate — residential mortgage 32 52 4 32 32 5 Home equity loans 74 80 10 61 61 9 Consumer direct loans 4 4 — 4 4 — Credit cards 3 3 — 2 2 — Consumer indirect loans 33 33 3 32 32 3 Total consumer loans 146 172 17 131 131 17 Total loans with an allowance recorded 210 266 24 141 159 23 Total $ 422 $ 532 $ 24 $ 354 $ 405 $ 23 (a) The Recorded Investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. This amount is a component of total loans on our Consolidated Balance Sheet. (b) The Unpaid Principal Balance represents the customer’s legal obligation to us. The following table sets forth a further breakdown of the average individually impaired loans reported by Key: Average Recorded Investment (a) Three Months Ended June 30, Six Months Ended June 30, in millions 2018 2017 2018 2017 Commercial and industrial $ 178 $ 201 $ 161 $ 225 Commercial real estate: Commercial mortgage 16 15 16 10 Construction — — — — Total commercial real estate loans 16 15 16 10 Total commercial loans 194 216 177 235 Real estate — residential mortgage 49 50 49 50 Home equity loans 124 122 121 122 Consumer direct loans 4 3 4 3 Credit cards 3 3 3 3 Consumer indirect loans 35 34 34 32 Total consumer loans 215 212 211 210 Total $ 409 $ 428 $ 388 $ 445 (a) The Recorded Investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. This amount is a component of total loans on our Consolidated Balance Sheet. Interest income recognized on the outstanding balances of accruing impaired loans totaled $3 million and $5 million for the three and six months ended June 30, 2018 , respectively, and $3 million and $6 million for the three and six months ended June 30, 2017 , respectively. TDRs We classify loan modifications as TDRs when a borrower is experiencing financial difficulties and we have granted a concession without commensurate financial, structural, or legal consideration. An acquired loan may only be classified as a TDR if a modification meeting the above TDR criteria is performed after the acquisition date. PCI loans cannot be classified as TDRs. All commercial and consumer loan TDRs, regardless of size, are individually evaluated for impairment to determine the probable loss content and are assigned a specific loan allowance. This designation has the effect of moving the loan from the general reserve methodology (i.e., collectively evaluated) to the specific reserve methodology (i.e., individually evaluated) and may impact the ALLL through a charge-off or increased loan loss provision. These components affect the ultimate allowance level. As TDRs are individually evaluated for impairment under the specific reserve methodology, subsequent defaults do not generally have a significant additional impact on the ALLL. Commitments outstanding to lend additional funds to borrowers whose loan terms have been modified in TDRs are $4 million and $2 million at June 30, 2018 , and December 31, 2017 , respectively. Our loan modifications are handled on a case-by-case basis and are negotiated to achieve mutually agreeable terms that maximize loan collectability and meet the borrower’s financial needs. The consumer TDR other concession category primarily includes those borrowers’ debts that are discharged through bankruptcy and have not been formally re-affirmed. At June 30, 2018 , and December 31, 2017 , the recorded investment of consumer residential mortgage loans in the process of foreclosure was approximately $146 million and $142 million , respectively. At June 30, 2018 , and December 31, 2017 , we had $26 million and $31 million , respectively, of OREO which included the carrying value of foreclosed residential real estate of approximately $23 million and $26 million , respectively. The following table shows the post-modification outstanding recorded investment by concession type for our commercial and consumer accruing and nonaccruing TDRs that occurred during the periods indicated: Three Months Ended June 30, Six Months Ended June 30, in millions 2018 2017 2018 2017 Commercial loans: Forgiveness of principal $ 5 — $ 5 — Extension of Maturity Date 14 $ 15 15 $ 17 Payment or Covenant Modification/Deferment 20 11 20 35 Bankruptcy Plan Modification 7 29 7 29 Total $ 46 $ 55 $ 47 $ 81 Consumer loans: Interest rate reduction $ 10 $ 4 $ 18 $ 7 Forgiveness of principal — — — — Other 9 4 21 17 Total $ 19 $ 8 $ 39 $ 24 Total commercial and consumer TDRs $ 65 $ 63 $ 86 $ 105 The following table summarizes the change in the post-modification outstanding recorded investment of our accruing and nonaccruing TDRs during the periods indicated: Three Months Ended June 30, Six Months Ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of the period $ 317 $ 302 $ 317 $ 280 Additions 54 67 75 114 Payments (22 ) (33 ) (41 ) (47 ) Charge-offs (2 ) (3 ) (4 ) (14 ) Balance at end of period (a) $ 347 $ 333 $ 347 $ 333 A further breakdown of TDRs included in nonperforming loans by loan category for the periods indicated are as follows: June 30, 2018 December 31, 2017 Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment dollars in millions LOAN TYPE Nonperforming: Commercial and industrial 44 $ 106 $ 86 20 $ 109 $ 86 Commercial real estate: Commercial mortgage 6 13 9 8 16 12 Total commercial real estate loans 6 13 9 8 16 12 Total commercial loans 50 119 95 28 125 98 Real estate — residential mortgage 264 18 17 308 18 18 Home equity loans 1,072 60 57 1,025 64 57 Consumer direct loans 119 2 2 114 2 2 Credit cards 252 1 1 322 2 1 Consumer indirect loans 878 16 12 825 16 13 Total consumer loans 2,585 97 89 2,594 102 91 Total nonperforming TDRs 2,635 216 184 2,622 227 189 Prior-year accruing: (a) Commercial and industrial 18 54 37 4 30 13 Commercial real estate Commercial mortgage — — — — — — Total commercial real estate loans — — — — — — Total commercial loans 18 54 37 4 30 13 Real estate — residential mortgage 517 37 32 484 31 31 Home equity loans 1,440 85 68 1,276 75 59 Consumer direct loans 82 4 3 48 3 2 Credit cards 513 3 1 430 1 1 Consumer indirect loans 501 35 22 320 31 22 Total consumer loans 3,053 164 126 2,558 141 115 Total prior-year accruing TDRs 3,071 218 163 2,562 171 128 Total TDRs 5,706 $ 434 $ 347 5,184 $ 398 $ 317 (a) All TDRs that were restructured prior to January 1, 2018 , and January 1, 2017 , and are fully accruing. Commercial loan TDRs are considered defaulted when principal and interest payments are 90 days past due. Consumer loan TDRs are considered defaulted when principal and interest payments are more than 60 days past due. During the three months ended June 30, 2018 , there were no commercial loan TDRs and 55 consumer loan TDRs with a combined recorded investment of $1 million that experienced payment defaults after modifications resulting in TDR status during 2017 . During the three months ended June 30, 2017 , there were no commercial loan TDRs and 52 consumer loan TDRs with a combined recorded investment of $2 million that experienced payment defaults after modifications resulting in TDR status during 2016 . During the six months ended June 30, 2018 , there were no commercial loan TDRs and 96 consumer loan TDRs with a combined recorded investment of $2 million that experienced payment defaults after modifications resulting in TDR status during 2017 . During the six months ended June 30, 2017 , there were no commercial loan TDRs and 55 consumer loan TDRs with a combined recorded investment of $2 million that experienced payment defaults after modifications resulting in TDR status during 2016 . ALLL and Liability for Credit Losses on Unfunded Lending-Related Commitments We determine the appropriate level of the ALLL on at least a quarterly basis. The methodology is described in Note 1 (“Summary of Significant Accounting Policies”) under the heading “Allowance for Loan and Lease Losses” beginning on page 102 of our 2017 Form 10-K. The ALLL on the acquired non-impaired loan portfolio is estimated using the same methodology as the originated portfolio, however, the estimated ALLL is compared to the remaining accretable yield to determine if an ALLL must be recorded. For PCI loans, Key estimates cash flows expected to be collected quarterly. Decreases in expected cash flows are recognized as impairment through a provision for loan and lease losses and an increase in the ALLL. There was less than $1 million of provision for loan and lease losses on PCI loans during the six months ended June 30, 2018 , and a credit of $3 million during the three months ended June 30, 2018 . There was $4 million of provision for loan and lease losses on PCI loans during the six months ended June 30, 2017 , and less than $1 million of provision for loan and lease losses on PCI loans during the three months ended June 30, 2017 . There was $3 million of provision for loan and lease losses on PCI loans during the twelve months ended December 31, 2017 . The ALLL at June 30, 2018 , represents our best estimate of the incurred credit losses inherent in the loan portfolio at that date. The changes in the ALLL by loan category for the periods indicated are as follows: Three months ended June 30, 2018 : in millions March 31, 2018 Provision Charge-offs Recoveries June 30, 2018 Commercial and Industrial $ 533 $ 41 $ (39 ) $ 7 $ 542 Commercial real estate: Real estate — commercial mortgage 136 4 (2 ) 1 139 Real estate — construction 33 (5 ) — — 28 Total commercial real estate loans 169 (1 ) (2 ) 1 167 Commercial lease financing 40 4 (4 ) — 40 Total commercial loans 742 44 (45 ) 8 749 Real estate — residential mortgage 9 1 — — 10 Home equity loans 38 2 (6 ) 3 37 Consumer direct loans 27 6 (9 ) 2 26 Credit cards 45 11 (12 ) 2 46 Consumer indirect loans 20 2 (7 ) 4 19 Total consumer loans 139 22 (34 ) 11 138 Total ALLL — continuing operations 881 66 (a) (79 ) 19 887 Discontinued operations 16 — (3 ) 1 14 Total ALLL — including discontinued operations $ 897 $ 66 $ (82 ) $ 20 $ 901 (a) Excludes a credit for losses on lending-related commitments of $2 million . Three months ended June 30, 2017 : in millions March 31, 2017 Provision Charge-offs Recoveries June 30, 2017 Commercial and Industrial $ 512 $ 54 $ (40 ) $ 2 $ 528 Commercial real estate: Real estate — commercial mortgage 146 1 (3 ) — 144 Real estate — construction 29 (1 ) — — 28 Total commercial real estate loans 175 — (3 ) — 172 Commercial lease financing 40 1 (1 ) — 40 Total commercial loans 727 55 (44 ) 2 740 Real estate — residential mortgage 18 (6 ) (4 ) 1 9 Home equity loans 53 (7 ) (9 ) 5 42 Consumer direct loans 24 7 (8 ) 2 25 Credit cards 38 16 (12 ) 2 44 Consumer indirect loans 10 1 (5 ) 4 10 Total consumer loans 143 11 (38 ) 14 130 Total ALLL — continuing operations 870 66 (82 ) 16 870 Discontinued operations 23 — (4 ) 2 21 Total ALLL — including discontinued operations $ 893 $ 66 $ (86 ) $ 18 $ 891 Six months ended June 30, 2018 : in millions December 31, 2017 Provision Charge-offs Recoveries June 30, 2018 Commercial and Industrial 529 $ 76 $ (76 ) $ 13 $ 542 Commercial real estate: Real estate — commercial mortgage 133 8 (3 ) 1 139 Real estate — construction 30 (3 ) — 1 28 Total commercial real estate loans 163 5 (3 ) 2 167 Commercial lease financing 43 1 (5 ) 1 40 Total commercial loans 735 82 (84 ) 16 749 Real estate — residential mortgage 7 4 (1 ) — 10 Home equity loans 43 (2 ) (10 ) 6 37 Consumer direct loans 28 11 (17 ) 4 26 Credit cards 44 23 (24 ) 3 46 Consumer indirect loans 20 6 (15 ) 8 19 Total consumer loans 142 42 (67 ) 21 138 Total ALLL — continuing operations 877 124 (a) (151 ) 37 887 Discontinued operations 16 2 (7 ) 3 14 Total ALLL — including discontinued operations $ 893 $ 126 $ (158 ) $ 40 $ 901 (a) Excludes a provision for losses on lending-related commitments of $1 million . Six months ended June 30, 2017 : in millions December 31, 2016 Provision Charge-offs Recoveries June 30, 2017 Commercial and Industrial $ 508 $ 85 $ (72 ) $ 7 $ 528 Commercial real estate: Real estate — commercial mortgage 144 3 (3 ) — 144 Real estate — construction 22 5 — 1 28 Total commercial real estate loans 166 8 (3 ) 1 172 Commercial lease financing 42 4 (8 ) 2 40 Total commercial loans 716 97 (83 ) 10 740 Real estate — residential mortgage 17 (9 ) (2 ) 3 9 Home equity loans 54 (3 ) (17 ) 8 42 Consumer direct loans 24 16 (18 ) 3 25 Credit cards 38 26 (23 ) 3 44 Consumer indirect loans 9 9 (16 ) 8 10 Total consumer loans 142 39 (76 ) 25 130 Total ALLL — continuing operations 858 136 (a) (159 ) 35 870 Discontinued operations 24 3 (10 ) 4 21 Total ALLL — including discontinued operations $ 882 $ 139 $ (169 ) $ 39 $ 891 (a) Excludes a credit for losses on lending-related commitments of $7 million . A breakdown of the individual and collective ALLL and the corresponding loan balances as of June 30, 2018 , follows: Allowance Outstanding June 30, 2018 Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired Loans Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired in millions Commercial and industrial $ 7 $ 533 $ 2 $ 44,569 $ 187 $ 44,325 $ 57 Commercial real estate: Commercial mortgage — 136 3 14,162 20 13,930 212 Construction — 28 — 1,736 — 1,733 3 Total commercial real estate loans — 164 3 15,898 20 15,663 215 Commercial lease financing — 40 — 4,509 — 4,509 — Total commercial loans 7 737 5 64,976 207 64,497 272 Real estate — residential mortgage 4 5 1 5,452 48 5,071 333 Home equity loans 10 26 1 11,519 125 11,374 20 Consumer direct loans — 26 — 1,785 4 1,777 4 Credit cards — 46 — 1,094 3 1,091 — Consumer indirect loans 3 16 — 3,396 35 3,361 — Total consumer loans 17 119 2 23,246 215 22,674 357 Total ALLL — continuing operations 24 856 7 88,222 422 87,171 629 Discontinued operations 3 11 — 1,194 (a) 21 1,173 (a) — Total ALLL — including discontinued operations $ 27 $ 867 $ 7 $ 89,416 $ 443 $ 88,344 $ 629 (a) Amount includes $2 million of loans carried at fair value that are excluded from ALLL consideration. A breakdown of the individual and collective ALLL and the corresponding loan balances as of December 31, 2017 , follows: Allowance Outstanding December 31, 2017 Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired Loans Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired in millions Commercial and Industrial $ 6 $ 520 $ 3 $ 41,859 $ 136 $ 41,640 $ 83 Commercial real estate: Commercial mortgage — 131 2 14,088 12 13,828 248 Construction — 30 — 1,960 — 1,934 26 Total commercial real estate loans — 161 2 16,048 12 15,762 274 Commercial lease financing — 43 — 4,826 — 4,826 — Total commercial loans 6 724 5 62,733 148 62,228 357 Real estate — residential mortgage 5 2 — 5,483 49 5,079 355 Home equity loans 9 33 1 12,028 117 11,889 22 Consumer direct loans — 28 — 1,794 4 1,786 4 Credit cards — 44 — 1,106 2 1,104 — Consumer indirect loans 3 17 — 3,261 34 3,227 — Total consumer loans 17 124 1 23,672 206 23,085 381 Total ALLL — continuing operations 23 848 6 86,405 354 85,313 738 Discontinued operations 3 13 — 1,314 (a) 21 1,293 (a) — Total ALLL — including discontinued operations $ 26 $ 861 $ 6 $ 87,719 $ 375 $ 86,606 $ 738 (a) Amount includes $2 million of loans carried at fair value that are excluded from ALLL consideration. The liability for credit losses inherent in unfunded lending-related commitments, such as letters of credit and unfunded loan commitments, is included in “accrued expense and other liabilities” on the balance sheet. We establish the amount of this reserve by considering both historical trends and current market conditions quarterly, or more often if deemed necessary. Changes in the liability for credit losses on unfunded lending-related commitments are summarized as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of period $ 60 $ 48 $ 57 $ 55 Provision (credit) for losses on lending-related commitments (2 ) — 1 (7 ) Balance at end of period $ 58 $ 48 $ 58 $ 48 PCI Loans Purchased loans that have evidence of deterioration in credit quality since origination and for which it is probable, at acquisition, that all contractually required payments will not be collected are deemed PCI. Our policies for determining, recording payments on, and derecognizing PCI loans are disclosed in Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Purchased Loans” beginning on page 107 of our 2017 Form 10-K. We have PCI loans from two separate acquisitions, one in 2012 and one in 2016. The following tables present the roll-forward of the accretable yield and the beginning and ending outstanding unpaid principal balance and carrying amount of all PCI loans for the three and six months ended June 30, 2018 , and the twelve months ended December 31, 2017 . Three Months Ended June 30, Six Months Ended June 30, 2018 2018 in millions Accretable Yield Carrying Amount Outstanding Unpaid Principal Balance Accretable Yield Carrying Amount Outstanding Unpaid Principal Balance Balance at beginning of period $ 132 $ 812 $ 930 $ 131 $ 738 $ 803 Additions — — Accretion (11 ) (23 ) Net reclassifications from nonaccretable to accretable 6 28 Payments received, net (6 ) (15 ) Disposals — — Balance at end of period $ 121 $ 622 $ 669 $ 121 $ 622 $ 669 Twelve Months Ended December 31, 2017 in millions Accretable Yield Carrying Amount Outstanding Unpaid Principal Balance Balance at beginning of period $ 197 $ 865 $ 1,002 Additions (32 ) Accretion (44 ) Net reclassifications from nonaccretable to accretable 15 Payments received, net (4 ) Disposals (1 ) Balance at end of period $ 131 $ 738 $ 803

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	5. Fair Value Measurements Fair Value Determination In accordance with GAAP, Key measures certain assets and liabilities at fair value. Fair value is defined as the price to sell an asset or transfer a liability in orderly transaction between market participants in our principal market. Additional information regarding our accounting policies for determining fair value is provided in Note 7 (“ Fair Value Measurements ”) and Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Fair Value Measurements” of our 2017 Form 10-K. Assets and Liabilities Measured at Fair Value on a Recurring Basis Certain assets and liabilities are measured at fair value on a recurring basis in accordance with GAAP. The following tables present these assets and liabilities at June 30, 2018 , and December 31, 2017 . June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total in millions ASSETS MEASURED ON A RECURRING BASIS Trading account assets: U.S. Treasury, agencies and corporations — $ 537 — $ 537 — 615 — 615 States and political subdivisions — 36 — 36 — 37 — 37 Other mortgage-backed securities — 137 — 137 — 104 — 104 Other securities — 107 — 107 — 65 — 65 Total trading account securities — 817 — 817 — 821 — 821 Commercial loans — 16 — 16 — 15 — 15 Total trading account assets — 833 — 833 — 836 — 836 Securities available for sale: U.S. Treasury, agencies and corporations — 146 — 146 — 157 — 157 States and political subdivisions — 7 — 7 — 9 — 9 Agency residential collateralized mortgage obligations — 13,894 — 13,894 — 14,660 — 14,660 Agency residential mortgage-backed securities — 1,367 — 1,367 — 1,439 — 1,439 Agency commercial mortgage-backed securities — 1,933 — 1,933 — 1,854 — 1,854 Other securities — — $ 20 20 — — 20 20 Total securities available for sale — 17,347 20 17,367 — 18,119 20 18,139 Other investments: Principal investments: Direct — — 13 13 — — 13 13 Indirect (measured at NAV) (a) — — — 109 — — — 124 Total principal investments — — 13 122 — — 13 137 Equity investments: Direct — — 7 7 — 4 3 7 Direct (measured at NAV) (a) — — — 1 — — — — Total equity investments — — 7 8 — 4 3 7 Total other investments — — 20 130 — 4 16 144 Loans, net of unearned income — — 3 3 — — 2 2 Loans held for sale — 58 — 58 — 70 1 71 Derivative assets: Interest rate — 338 5 343 — 713 9 722 Foreign exchange $ 84 32 — 116 $ 100 $ 30 $ — $ 130 Commodity — 494 — 494 — 255 — 255 Credit — — — — — — 1 1 Other — 1 3 4 — 1 3 4 Derivative assets 84 865 8 957 100 999 13 1,112 Netting adjustments (b) — — — (219 ) — — — (443 ) Total derivative assets 84 865 8 738 100 999 13 669 Accrued income and other assets — — — — — — — — Total assets on a recurring basis at fair value $ 84 $ 19,103 $ 51 $ 19,129 $ 100 $ 20,028 $ 52 $ 19,861 LIABILITIES MEASURED ON A RECURRING BASIS Bank notes and other short-term borrowings: Short positions $ 6 $ 633 — $ 639 $ 72 $ 562 $ — $ 634 Derivative liabilities: Interest rate — 423 — 423 — 520 — 520 Foreign exchange 73 30 — 103 98 26 — 124 Commodity — 484 — 484 — 246 — 246 Credit — 3 9 12 — 4 — 4 Other — 2 — 2 — 13 — 13 Derivative liabilities 73 942 9 1,024 98 809 — 907 Netting adjustments (b) — — — (598 ) — — — (616 ) Total derivative liabilities 73 942 9 426 98 809 — 291 Accrued expense and other liabilities — — — — — — — — Total liabilities on a recurring basis at fair value $ 79 $ 1,575 9 $ 1,065 $ 170 $ 1,371 $ — $ 925 (a) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheet. (b) Netting adjustments represent the amounts recorded to convert our derivative assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The net basis takes into account the impact of bilateral collateral and master netting agreements that allow us to settle all derivative contracts with a single counterparty on a net basis and to offset the net derivative position with the related cash collateral. Total derivative assets and liabilities include these netting adjustments. Qualitative Disclosures of Valuation Techniques The following describes the valuation techniques and significant inputs for Level 2 and Level 3 assets and liabilities: Securities (trading account assets and available for sale) . We own several types of securities, requiring a range of valuation methods: • Level 2 securities include municipal bonds, bonds backed by the U.S. government, corporate bonds, agency residential and CMBS, securities issued by the U.S. Treasury, money markets, and certain agency and corporate CMOs. Fair value is determined using pricing models (either by a third-party pricing service or internally) or quoted prices of similar securities. • Our Level 3 instruments consist principally of debt securities. The securities are valued using a cash flow analysis of the associated private company issuers based on internal models or a third party valuation service. We also employ a market approach that utilizes revenue multiples of comparable companies. We reference guideline public companies with growth prospects, margin, and risks that are comparable to the subject companies. The valuations of the securities are negatively affected by projected net losses of the associated private companies and positively affected by projected net gains. The valuations provided by the third-party pricing service are based on observable market inputs, which include benchmark yields, reported trades, issuer spreads, benchmark securities, bids, offers, and reference data obtained from market research publications. Inputs used by the third-party pricing service in valuing CMOs and other mortgage-backed securities also include new issue data, monthly payment information, whole loan collateral performance, and “To Be Announced” prices. We validate the pricing methodologies utilized by our third-party pricing service to ensure that the fair value determination is consistent with the applicable accounting guidance. This includes comparing the actual inputs used by our third-party pricing service to comparable inputs for similar securities and comparing the fair values to prices from other independent sources for the same and similar securities. Commercial loans (trading account assets) . Commercial loans recorded as trading account assets are valued based on market spreads since there is an active market for similar assets. Bid and ask prices are received from multiple loan dealers and valuations reflect prices within the bid-ask spread that are most representative of fair value for the respective loans. The price point used within the bid/ask spread is further validated using an independent, third party service provider. Principal investments . Principal investments consist of investments in equity and debt instruments made by our principal investing entities. They include direct investments (investments made in a particular company) and indirect investments (investments made through funds that include other investors). In most cases, quoted market prices are not available for our direct investments, and we must estimate the fair value based on operating performance, market multiples for comparable businesses, and unique facts and circumstances related to each individual investment. Indirect investments are valued using a methodology that is consistent with accounting guidance allowing us to estimate fair value based upon net asset value per share (or its equivalent, such as member units or an ownership interest in partners’ capital to which a proportionate share of net assets is attributed). The following table presents the fair value of our direct and indirect principal investments and related unfunded commitments at June 30, 2018 , as well as financial support provided for the three and six months ended June 30, 2018 , and June 30, 2017 . Financial support provided Three months ended June 30, Six months ended June 30, June 30, 2018 2018 2017 2018 2017 in millions Fair Value Unfunded Commitments Funded Commitments Funded Other Funded Commitments Funded Other Funded Commitments Funded Other Funded Commitments Funded Other INVESTMENT TYPE Direct investments (a) $ 13 — — — — — — — — $ — Indirect investments (measured at NAV) 109 $ 28 — — $ — — $ 1 — $ 1 — Total $ 122 $ 28 — — $ — — $ 1 — $ 1 $ — (a) Our direct investments consist of equity and debt investments directly in independent business enterprises. Operations of the business enterprises are handled by management of the portfolio company. The purpose of funding these enterprises is to provide financial support for business development and acquisition strategies. We infuse equity capital based on an initial contractual cash contribution and later from additional requests on behalf of the companies’ management. (b) Our indirect investments consist of buyout funds, venture capital funds, and fund of funds. These investments are generally not redeemable. Instead, distributions are received through the liquidation of the underlying investments of the fund. An investment in any one of these funds typically can be sold only with the approval of the fund’s general partners. We estimate that the underlying investments of the funds will be liquidated over a period of one to six years . The purpose of funding our capital commitments to these investments is to allow the funds to make additional follow-on investments and pay fund expenses until the fund dissolves. We, and all other investors in the fund, are obligated to fund the full amount of our respective capital commitments to the fund based on our and their respective ownership percentages, as noted in the applicable Limited Partnership Agreement. Other Equity Investments. Our other equity investments measured on a recurring basis are direct investments in equity instruments of private companies. Quoted market prices are not available for these investments and we must perform valuations using other methods in a similar manner to our direct principal investments. Loans Held for Sale and Held for Investment. Residential mortgage loans are valued based on quoted market prices, where available, prices for other traded mortgage loans with similar characteristics, and purchase commitments and bid information received from market participants. We have elected the fair value option for residential mortgage loans held for sale as this aligns with the related forward mortgage loan sale commitments. Our residential mortgage activity also includes temporarily unsalable residential mortgage loans that are included in “Loans, net of unearned income” and loans with salability issues included in “Loans held for sale” on the balance sheet. These loans have an origination defect that makes them temporarily unable to be sold into the performing loan sales market. Because transaction details regarding sales of this type of loan are often unavailable, unobservable bid information from brokers and investors is heavily relied upon. Accordingly, based on the significance of unobservable inputs, these loans are classified as Level 3. Derivatives . The majority of our derivative positions are Level 2 instruments, which are valued using internally developed models, based on market convention. These models use observable market inputs, such as interest rate curves, LIBOR and Overnight Index Swap discount rates and curves, index pricing curves, foreign currency curves, volatility surfaces (a three-dimensional graph of implied volatility against strike price and maturity) and current prices for mortgage securities and investor supplied prices. Level 3 derivative instruments primarily consist of interest rate lock commitments and several customized derivative instruments. The value of interest rate lock commitments is based on interest rates observable in the market and the probability of the loan closing. Therefore, the valuation methodology employs a model which uses current interest rates and adjusts the probability of the loan closing at the approved terms in the current interest rate environment. Various other customized derivative instruments are priced using internally developed models which leverage market and internal data and assumptions. Liability for short positions. Level 2 items are fixed income securities held by our broker dealer in its trading inventory. These items are measured at fair value based upon market activity, spreads, credit ratings and interest rates for each security type. Additionally, recent values used in transactions for the same or similar securities are also utilized in the valuation. Changes in Level 3 Fair Value Measurements The following table shows the components of the change in the fair values of our Level 3 financial instruments for the three and six months ended June 30, 2018 , and June 30, 2017 . in millions Beginning of Period Balance Gains (Losses) Included in Other Comprehensive Income Gains (Losses) Included in Earnings Purchases Sales Settlements Transfers Other Transfers into Level 3 (a) Transfers out of Level 3 (a) End of Period Balance Unrealized Gains (Losses) Included in Earnings Six months ended June 30, 2018 Securities available for sale Other securities $ 20 $ — — — — — — — — $ 20 — Other investments Principal investments Direct 13 — $ — (b) 1 (1 ) — — — — 13 $ 1 (b) Equity investments Direct 3 — — — — — — $ 4 — 7 — Loans held for sale 1 — — — (1 ) — — — — — — Loans held for investment 2 — — — — — 1 — — 3 — Derivative instruments (c) Interest rate 9 — (2 ) (d) 1 (2 ) — — 4 (e) $ (5 ) (e) 5 — Credit 1 — (20 ) (d) — — $ 10 — — — (9 ) — Other (f) 3 — — — — — — — — 3 — Three months ended June 30, 2018 Securities available for sale Other securities $ 20 $ — — — — — — — $ — $ 20 — Other investments Principal investments Direct 12 — $ 1 (b) 1 (1 ) — — — — 13 2 (b) Equity investments Direct 7 — — — — — — — — 7 — Loans held for sale 1 — — — (1 ) — — — — — — Loans held for investment 2 — — — — — 1 — — 3 — Derivative instruments (c) Interest rate 4 — (1 ) (d) — (2 ) — — 4 (e) — (e) 5 — Credit — — (15 ) (d) — — $ 6 — — — (9 ) — Other (f) 3 — — — — — — — — 3 — in millions Beginning of Period Balance Gains (Losses) Included in Other Comprehensive Income Gains (Losses) Included in Earnings Purchases Sales Settlements Transfers Other Transfers into Level 3 (a) Transfers out of Level 3 (a) End of Period Balance Unrealized Gains (Losses) Included in Earnings Six months ended June 30, 2017 Securities available for sale Other securities $ 17 3 — — — — — — — $ 20 — Other investments Principal investments Direct 27 $ — $ (5 ) (b) — $ (7 ) — — — — 15 $ (3 ) (b) Derivative instruments (c) Interest rate 7 — — — — — — $ 12 (e) $ (3 ) (e) 16 — Credit 1 — (7 ) (d) — — $ 7 — — — 1 — Other (f) 2 — — — — — $ 2 — — 4 — Three months ended June 30, 2017 Securities available for sale Other securities $ 17 3 — — — — — — — $ 20 — Other investments Principal investments Direct 21 $ — $ (3 ) (b) — $ (3 ) — — — — 15 $ 3 (b) Derivative instruments (c) Interest rate 5 — — — — — — $ 11 (e) $ — (e) 16 — Credit 1 — (4 ) (d) — — $ 4 — — — 1 — Other (f) 4 — — $ — — — $ — — — 4 — (a) Our policy is to recognize transfers into and transfers out of Level 3 as of the end of the reporting period. (b) Realized and unrealized gains and losses on principal investments are reported in “other income” on the income statement. (c) Amounts represent Level 3 derivative assets less Level 3 derivative liabilities. (d) Realized and unrealized gains and losses on derivative instruments are reported in “corporate services income” and “other income” on the income statement. (e) Certain derivatives previously classified as Level 2 were transferred to Level 3 because Level 3 unobservable inputs became significant. Certain derivatives previously classified as Level 3 were transferred to Level 2 because Level 3 unobservable inputs became less significant. (f) Amounts represent Level 3 interest rate lock commitments. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Certain assets and liabilities are measured at fair value on a nonrecurring basis in accordance with GAAP. The adjustments to fair value generally result from the application of accounting guidance that requires assets and liabilities to be recorded at the lower of cost or fair value, or assessed for impairment. There were no liabilities measured at fair value on a nonrecurring basis at June 30, 2018 , and December 31, 2017 . The following table presents our assets measured at fair value on a nonrecurring basis at June 30, 2018 , and December 31, 2017 : June 30, 2018 December 31, 2017 in millions Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ASSETS MEASURED ON A NONRECURRING BASIS Impaired loans and leases — $ 3 $ 71 $ 74 — — $ 9 $ 9 Accrued income and other assets — — 2 2 — $ 5 133 (a) 138 Total assets on a nonrecurring basis at fair value — $ 3 $ 73 $ 76 — $ 5 $ 142 $ 147 (a) At December 31, 2017, we recorded $31 million of impairment related to $119 million of LIHTC and Historic Tax Credit investments impacted by the enactment of the TCJ Act. Refer to the “LIHTC and Historic Tax Credit Investments” section below for a description of the valuation technique and inputs applied for this fair value measurement. Impaired loans and leases . The following two internal methods are used to value impaired loans and leases: • Cash flow analysis considers internally developed inputs, such as discount rates, default rates, costs of foreclosure, and changes in collateral values. • The fair value of the underlying collateral, which may take the form of real estate or personal property, is based on internal estimates, field observations, and assessments provided by third-party appraisers. Impairment valuations are back-tested each quarter, based on a look-back of actual incurred losses on closed deals previously evaluated for impairment. The overall percent variance of actual net loan charge-offs on closed deals compared to the specific allocations on such deals is considered in determining each quarter’s specific allocations. Commercial loans held for sale . Through a quarterly analysis of our loan portfolios held for sale, which include both performing and nonperforming commercial loans, we determine any adjustments necessary to record the portfolios at the lower of cost or fair value in accordance with GAAP. For loans sold in an active market, we utilize non-binding bids for the respective loans or similar loans, or recent sales to determine the fair value. For inactive markets, we assess appraisal values, strength of sponsor/guarantor, loan pricing relative to current comparable transactions, current market conditions and market demographics. Our analysis concluded that there were no commercial loans held for sale adjusted to fair value at June 30, 2018 , and December 31, 2017 . Direct financing leases and operating lease assets held for sale . Valuations of direct financing leases and operating lease assets held for sale are performed using an internal model that relies on market data, such as swap rates and bond ratings, as well as on our own assumptions about the exit market for the leases and details about the individual leases in the portfolio. The inputs based on our assumptions include changes in the value of leased items and internal credit ratings. These leases have been classified as Level 3 assets. Leases for which we receive a current nonbinding bid, and for which the sale is considered probable, may be classified as Level 2. No direct financing leases and operating lease assets held for sale were adjusted to fair value at June 30, 2018 , and December 31, 2017 . Other assets. OREO and other repossessed properties are valued based on inputs such as appraisals and third-party price opinions, less estimated selling costs. Generally, we classify these assets as Level 3, but OREO and other repossessed properties for which we receive binding purchase agreements are classified as Level 2. Returned lease inventory is valued based on market data for similar assets and is classified as Level 2. LIHTC and Historic Tax Credit Investments. Valuation of LIHTC and Historic Tax Credit (HTC) involves measuring the present value of future tax benefits and comparing that value against the current carrying value of the investment. LIHTC and HTC investments are impaired when it is more likely than not that the carrying amount of the investment will not be realized. A primary driver of impairment in the fourth quarter of 2017 was the enactment of the TCJ Act, which reduced future depreciation tax benefits expected to be realized by certain LIHTC and HTC investments. No impairment was recorded for the three and six months ended June 30, 2018 . Other Equity Investments. We have other investments in equity securities that do not have readily determinable fair values and do not qualify for the practical expedient to measure the investment using a net asset value per share. We have elected to measure these securities at cost less impairment plus or minus adjustments due to observable orderly transactions. Impairment is recorded w hen there is evidence that the expected fair value of the investment has declined to below the recorded cost. At each reporting period, we assess if these investments continue to qualify for this measurement alternative. At June 30, 2018 , the carrying amount of equity investments recorded under this method was $93 million . No impairment was recorded for the three and six months ended June 30, 2018 . Quantitative Information about Level 3 Fair Value Measurements The range and weighted average of the significant unobservable inputs used to fair value our material Level 3 recurring and nonrecurring assets at June 30, 2018 , and December 31, 2017 , along with the valuation techniques used, are shown in the following table: June 30, 2018 Fair Value of Level 3 Assets Valuation Technique Significant Unobservable Input Range (Weighted-Average) dollars in millions Recurring Other investments — principal investments — direct: $ 13 Individual analysis of the condition of each investment Debt instruments EBITDA multiple N/A (6.93) Equity instruments of private companies EBITDA multiple N/A (6.93) Nonrecurring Impaired loans 71 Fair value of underlying collateral Discount 0.00 - 75.00% (22.00%) December 31, 2017 Fair Value of Level 3 Assets Valuation Technique Significant Unobservable Input Range (Weighted-Average) dollars in millions Recurring Other investments — principal investments — direct: $ 13 Individual analysis of the condition of each investment Debt instruments EBITDA multiple N/A (6.00) Equity instruments of private companies EBITDA multiple N/A (6.00) Nonrecurring Impaired loans 9 Fair value of underlying collateral Discount 0.00 - 50.00% (23.00%) Fair Value Disclosures of Financial Instruments The levels in the fair value hierarchy ascribed to our financial instruments and the related carrying amounts at June 30, 2018 , and December 31, 2017 , are shown in the following tables. Assets and liabilities are further arranged by measurement category. June 30, 2018 Fair Value in millions Carrying Amount Level 1 Level 2 Level 3 Measured at NAV Netting Adjustment Total ASSETS (by measurement category) Fair value - net income Trading account assets (b) $ 833 — $ 833 — — — $ 833 Other investments (b) 709 — — $ 599 $ 110 — 709 Loans, net of unearned income (d) 3 — — 3 — — 3 Loans held for sale (b) 58 — 58 — — — 58 Derivative assets - trading (b) 690 $ 81 828 8 — $ (227 ) (f) 690 Fair value - OCI Securities available for sale (b) 17,367 — 17,347 $ 20 — — 17,367 Derivative assets - hedging (b) 48 3 37 — — 8 (f) 48 Amortized cost Held-to-maturity securities (c) 12,277 — 11,735 — — — 11,735 Loans, net of unearned income (d) 87,332 — — 84,969 — — 84,969 Loans held for sale (b) 1,360 — — 1,360 — — 1,360 Other Cash and short-term investments (a) 3,430 3,430 — — — — 3,430 LIABILITIES (by measurement category) Fair value - net income Derivative liabilities - trading (b) $ 426 $ 73 $ 940 9 — $ (596 ) (f) $ 426 Fair value - OCI Derivative liabilities - hedging (b) — — 1 — — (1 ) (f) — Amortized cost Time deposits (e) 12,490 — 12,557 — — — 12,557 Short-term borrowings (a) 2,306 $ 6 2,300 — — — 2,306 Long-term debt (e) 13,853 12,708 1,173 — — — 13,881 Other Deposits with no stated maturity (a) 92,058 — 92,058 — — — 92,058 December 31, 2017 Fair Value in millions Carrying Amount Level 1 Level 2 Level 3 Measured at NAV Netting Adjustment Total ASSETS (by measurement category) Fair value - net income Trading account assets (b) $ 836 — $ 836 — — — $ 836 Other investments (b) 726 — 4 $ 598 $ 124 — 726 Loans, net of unearned income (d) 2 — — 2 — — 2 Loans held for sale (b) 71 — 70 1 — — 71 Derivative assets - trading (b) 681 $ 99 918 13 — $ (349 ) (f) 681 Fair value - OCI Securities available for sale (b) 18,139 — 18,119 20 — — 18,139 Derivative assets - hedging (b) (12 ) 1 81 — — (94 ) (f) (12 ) Amortized cost Held-to-maturity securities (c) 11,830 — 11,565 — — — 11,565 Loans, net of unearned income (d) 85,526 — — 84,003 — — 84,003 Loans held for sale (b) 1,036 — — 1,036 — — 1,036 Other Cash and short-term investments (a) 5,118 5,118 — — — — 5,118 LIABILITIES (by measurement category) Fair value - net income Derivative liabilities - trading (b) $ 289 $ 94 $ 763 — — $ (568 ) (f) $ 289 Fair value - OCI Derivative liabilities - hedging (b) 2 4 46 — — (48 ) (f) 2 Amortized cost Time deposits (e) 11,647 — 11,750 — — — 11,750 Short-term borrowings (a) 1,011 72 939 — — — 1,011 Long-term debt (e) 14,333 13,407 $ 1,219 — — — 14,626 Other Deposits with no stated maturity (a) 93,588 — 93,588 — — — 93,588 Valuation Methods and Assumptions (a) Fair value equals or approximates carrying amount. The fair value of deposits with no stated maturity does not take into consideration the value ascribed to core deposit intangibles. (b) Information pertaining to our methodology for measuring the fair values of these assets and liabilities is included in the sections entitled “Qualitative Disclosures of Valuation Techniques” and “Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis” in this Note. Investments accounted for under the cost method (or cost less impairment adjusted for observable price changes for certain equity investments) are classified as Level 3 assets. These investments are not actively traded in an open market as sales for these types of investments are rare. The carrying amount of the investments carried at cost are adjusted for declines in value if they are considered to be other-than-temporary (or due to observable orderly transactions of the same issuer for equity investments eligible for the cost less impairment measurement alternative). These adjustments are included in “other income” on the income statement. (c) Fair values of held-to-maturity securities are determined by using models that are based on security-specific details, as well as relevant industry and economic factors. The most significant of these inputs are quoted market prices, interest rate spreads on relevant benchmark securities, and certain prepayment assumptions. We review the valuations derived from the models to ensure that they are reasonable and consistent with the values placed on similar securities traded in the secondary markets. (d) The fair value of loans is based on the present value of the expected cash flows. The projected cash flows are based on the contractual terms of the loans, adjusted for prepayments and use of a discount rate based on the relative risk of the cash flows, taking into account the loan type, maturity of the loan, liquidity risk, servicing costs, and a required return on debt and capital. In addition, an incremental liquidity discount is applied to certain loans, using historical sales of loans during periods of similar economic conditions as a benchmark. The fair value of loans includes lease financing receivables at their aggregate carrying amount, which is equivalent to their fair value. (e) Fair values of time deposits and long-term debt are based on discounted cash flows utilizing relevant market inputs. (f) Netting adjustments represent the amounts recorded to convert our derivative assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The net basis takes into account the impact of bilateral collateral and master netting agreements that allow us to settle all derivative contracts with a single counterparty on a net basis and to offset the net derivative position with the related cash collateral. Total derivative assets and liabilities include these netting adjustments. Education lending business . The discontinued education lending business consists of loans in portfolio recorded at carrying value with appropriate valuation reserves, and loans in portfolio recorded at fair value. All of these loans were excluded from the table above as follows: • Loans at carrying value, net of allowance, of $1.2 billion ( $1.0 billion at fair value) at June 30, 2018 , and $1.3 billion ( $1.1 billion at fair value) at December 31, 2017 ; • Portfolio loans at fair value of $2 million at June 30, 2018 , and $2 million at December 31, 2017 .

Securities

Securities	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Securities	6. Securities The amortized cost, unrealized gains and losses, and approximate fair value of our securities available for sale and held-to-maturity securities are presented in the following tables. Gross unrealized gains and losses represent the difference between the amortized cost and the fair value of securities on the balance sheet as of the dates indicated. Accordingly, the amount of these gains and losses may change in the future as market conditions change. June 30, 2018 December 31, 2017 in millions Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value SECURITIES AVAILABLE FOR SALE U.S. Treasury, agencies, and corporations $ 150 — $ 4 $ 146 $ 159 $ — $ 2 $ 157 States and political subdivisions 7 — — 7 9 — — 9 Agency residential collateralized mortgage obligations 14,435 $ 5 546 13,894 14,985 10 335 14,660 Agency residential mortgage-backed securities 1,407 2 42 1,367 1,456 3 20 1,439 Agency commercial mortgage-backed securities 2,041 — 108 1,933 1,920 — 66 1,854 Other securities 17 3 — 20 17 3 — 20 Total securities available for sale $ 18,057 $ 10 $ 700 $ 17,367 $ 18,546 $ 16 $ 423 $ 18,139 HELD-TO-MATURITY SECURITIES Agency residential collateralized mortgage obligations $ 7,699 1 $ 372 $ 7,328 $ 8,055 $ — $ 224 $ 7,831 Agency residential mortgage-backed securities 531 $ — 17 514 574 1 4 571 Agency commercial mortgage-backed securities 4,032 — 154 3,878 3,186 6 44 3,148 Other securities 15 — — 15 15 — — 15 Total held-to-maturity securities $ 12,277 $ 1 $ 543 $ 11,735 $ 11,830 $ 7 $ 272 $ 11,565 The following table summarizes our securities that were in an unrealized loss position as of June 30, 2018 , and December 31, 2017 . Duration of Unrealized Loss Position Less than 12 Months 12 Months or Longer Total in millions Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses June 30, 2018 Securities available for sale: U.S Treasury, agencies, and corporations $ 39 $ 1 $ 107 $ 3 $ 146 $ 4 Agency residential collateralized mortgage obligations 5,742 141 7,230 405 12,972 546 Agency residential mortgage-backed securities 338 10 873 32 1,211 42 Agency commercial mortgage-backed securities 192 9 1,593 99 1,785 108 Held-to-maturity securities: Agency residential collateralized mortgage obligations 2,058 65 5,156 307 7,214 372 Agency residential mortgage-backed securities 330 10 184 7 514 17 Agency commercial mortgage-backed securities 3,030 104 477 50 3,507 154 Other securities (a) 9 — — — 9 — Total temporarily impaired securities $ 11,738 $ 340 $ 15,620 $ 903 $ 27,358 $ 1,243 December 31, 2017 Securities available for sale: U.S. Treasury, agencies, and corporations $ 41 $ — 116 2 $ 157 $ 2 Agency residential collateralized mortgage obligations 6,153 74 $ 7,270 $ 261 13,423 335 Agency residential mortgage-backed securities 666 7 702 13 1,368 20 Agency commercial mortgage-backed securities 205 4 1,649 62 1,854 66 Held-to-maturity securities: Agency residential collateralized mortgage obligations 2,201 27 5,599 197 7,800 224 Agency residential mortgage-backed securities 252 1 206 3 458 4 Agency commercial mortgage-backed securities 1,470 12 495 32 1,965 44 Other securities (a) 3 — 4 — 7 — Total temporarily impaired securities $ 10,991 $ 125 $ 16,041 $ 570 $ 27,032 $ 695 (a) Gross unrealized losses totaled less than $1 million for other securities held-to maturity at June 30, 2018 , and December 31, 2017 . At June 30, 2018 , we had $546 million of gross unrealized losses related to 465 fixed-rate agency residential CMOs that we invested in as part of our overall A/LM strategy. These securities had a weighted-average maturity of 4.69 years at June 30, 2018 . At June 30, 2018 , we also had $42 million of gross unrealized losses related to 266 agency residential mortgage-backed securities positions and $108 million of gross unrealized losses related to 14 agency commercial mortgage backed securities positions with weighted-average maturities of 3.98 years and 4.06 years, respectively. Because these securities have a fixed interest rate, their fair value is sensitive to movements in market interest rates. These unrealized losses are considered temporary since we expect to collect all contractually due amounts from these securities. Accordingly, these investments were reduced to their fair value through OCI, not through earnings. We regularly assess our securities portfolio for OTTI. The assessments are based on the nature of the securities, the underlying collateral, the financial condition of the issuer, the extent and duration of the loss, our intent related to the individual securities, and the likelihood that we will have to sell securities prior to expected recovery. As shown in the following table, we did not have any impairment losses recognized in earnings for the three and six months ended June 30, 2018 , and June 30, 2017 . Six months ended June 30, 2018 in millions Balance at December 31, 2017 $ 4 Impairment recognized in earnings — Balance at June 30, 2018 $ 4 At June 30, 2018 , securities available for sale and held-to-maturity securities totaling $7.9 billion were pledged to secure securities sold under repurchase agreements, to secure public and trust deposits, to facilitate access to secured funding, and for other purposes required or permitted by law. The following table shows our securities by remaining maturity. CMOs and other mortgage-backed securities available for sale portfolio and held-to-maturity portfolio are presented based on their expected average lives. The remaining securities, in both the available-for-sale and held-to-maturity portfolios, are presented based on their remaining contractual maturity. Actual maturities may differ from expected or contractual maturities since borrowers have the right to prepay obligations with or without prepayment penalties. Securities Available for Sale Held to Maturity Securities June 30, 2018 Amortized Cost Fair Value Amortized Cost Fair Value in millions Due in one year or less $ 113 $ 113 $ 43 $ 42 Due after one through five years 12,105 11,602 6,653 6,410 Due after five through ten years 5,823 5,636 5,581 5,283 Due after ten years 16 16 — — Total $ 18,057 $ 17,367 $ 12,277 $ 11,735

Derivatives and Hedging Activit

Derivatives and Hedging Activities	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging Activities	7. Derivatives and Hedging Activities We are a party to various derivative instruments, mainly through our subsidiary, KeyBank. The primary derivatives that we use are interest rate swaps, caps, floors, and futures; foreign exchange contracts; commodity derivatives; and credit derivatives. Generally, these instruments help us manage exposure to interest rate risk, mitigate the credit risk inherent in our loan portfolio, hedge against changes in foreign currency exchange rates, and meet client financing and hedging needs. At June 30, 2018 , after taking into account the effects of bilateral collateral and master netting agreements, we had $48 million of derivative assets and less than $1 million of derivative liabilities that relate to contracts entered into for hedging purposes. As of the same date, after taking into account the effects of bilateral collateral and master netting agreements and a reserve for potential future losses, we had derivative assets of $690 million and derivative liabilities of $426 million that were not designated as hedging instruments. These positions are primarily comprised of derivative contracts entered into for client accommodation purposes. Additional information regarding our accounting policies for derivatives is provided in Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Derivatives and Hedging” beginning on page 105 of our 2017 Form 10-K. Our derivative strategies and related risk management objectives are described in Note 9. Derivatives and Hedging Activities beginning on page 143 of our 2017 Form 10-K. Fair Values, Volume of Activity, and Gain/Loss Information Related to Derivative Instruments The following table summarizes the fair values of our derivative instruments on a gross and net basis as of June 30, 2018 , and December 31, 2017 . The derivative asset and liability balances are presented on a gross basis, prior to the application of bilateral collateral and master netting agreements, but after the variation margin payments with central clearing organizations have been applied as settlement, as applicable. Total derivative assets and liabilities are adjusted to take into account the impact of legally enforceable master netting agreements that allow us to settle all derivative contracts with a single counterparty on a net basis and to offset the net derivative position with the related cash collateral. Securities collateral related to legally enforceable master netting agreements is not offset on the balance sheet. Our derivative instruments are included in “accrued income and other assets” or “accrued expenses and other liabilities” on the balance sheet, as follows: June 30, 2018 December 31, 2017 Fair Value Fair Value in millions Notional Amount Derivative Assets Derivative Liabilities Notional Amount Derivative Assets Derivative Liabilities Derivatives designated as hedging instruments: Interest rate $ 28,918 $ 37 $ 2 $ 26,176 $ 81 $ 46 Foreign exchange 256 3 — 302 1 4 Total 29,174 40 2 26,478 82 50 Derivatives not designated as hedging instruments: Interest rate 66,309 306 421 61,390 641 474 Foreign exchange 9,378 113 103 8,317 129 120 Commodity 2,165 494 484 1,687 255 246 Credit 381 — 12 315 1 4 Other (a) 1,244 4 2 2,006 4 13 Total 79,477 917 1,022 73,715 1,030 857 Netting adjustments (b) — (219 ) (598 ) — (443 ) (616 ) Net derivatives in the balance sheet 108,651 738 426 100,193 669 291 Other collateral (c) — (2 ) (69 ) — (5 ) (84 ) Net derivative amounts $ 108,651 $ 736 $ 357 $ 100,193 $ 664 $ 207 (a) Other derivatives include interest rate lock commitments and forward sale commitments related to our residential mortgage banking activities, forward purchase and sales contracts consisting of contractual commitments associated with “to be announced” securities and when issued securities, and when-issued security transactions in connection with an “at-the-market” equity offering program. (b) Netting adjustments represent the amounts recorded to convert our derivative assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. (c) Other collateral represents the amount that cannot be used to offset our derivative assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. The other collateral consists of securities and is exchanged under bilateral collateral and master netting agreements that allow us to offset the net derivative position with the related collateral. The application of the other collateral cannot reduce the net derivative position below zero. Therefore, excess other collateral, if any, is not reflected above. Fair value hedges. During the six -month period ended June 30, 2018 , we did not exclude any portion of these hedging instruments from the assessment of hedge effectiveness. The following table summarizes the amounts that were recorded on the balance sheet as of June 30, 2018 , related to cumulative basis adjustments for fair value hedges. June 30, 2018 in millions Balance sheet line item in which the hedge item is included Carrying amount of hedged item (a) Hedge accounting basis adjustment (b) Interest rate contracts Long-term debt $ 9,481 $ (104 ) Interest rate contracts Certificate of deposit ($100,000 or more) 347 — Interest rate contracts Other time deposits 179 — (a) The carrying amount represents the portion of the liability designated as the hedged item. (b) Basis adjustment includes $11 million related to de-designated hedged items no longer in qualifying fair value hedging relationships. Cash flow hedges. During the six -month period ended June 30, 2018 , we did not exclude any portion of these hedging instruments from the assessment of hedge effectiveness. Considering the interest rates, yield curves, and notional amounts as of June 30, 2018 , we would expect to reclassify an estimated $68 million of after-tax net gains on derivative instruments designated as cash flow hedges from AOCI to income during the next 12 months . In addition, we expect to reclassify approximately $3 million of net losses related to terminated cash flow hedges from AOCI to income during the next 12 months. As of June 30, 2018 , the maximum length of time over which we hedge forecasted transactions is 10 years. The following tables summarize the effect of fair value and cash flow hedge accounting on the income statement for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 . Location and amount of net gains (losses) recognized in income on fair value and cash flow hedging relationships (a) in millions Interest expense – long-term debt Interest income – loans Interest expense - deposits Other income Three months ended June 30, 2018 Total amounts presented in the consolidated statement of income $ (102 ) $ 1,000 $ (112 ) $ 99 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items 22 — 1 — Recognized on derivatives designated as hedging instruments (25 ) — — — Net income (expense) recognized on fair value hedges (3 ) — 1 — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income 1 (25 ) — — Net income (expense) recognized on cash flow hedges $ 1 $ (25 ) — — Three months ended June 30, 2017 Total amounts presented in the consolidated statement of income $ (74 ) $ 948 $ (66 ) $ 85 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items — — — (5 ) Recognized on derivatives designated as hedging instruments 14 — — 5 Net income (expense) recognized on fair value hedges 14 — — — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income (1 ) 5 — — Gains (losses) (before tax) recognized in income for hedge ineffectiveness — — — — Net income (expense) recognized on cash flow hedges $ (1 ) $ 5 — — Location and amount of net gains (losses) recognized in income on fair value and cash flow hedging relationships (a) in millions Interest expense – long-term debt Interest income – loans Interest expense - deposits Other income Six months ended June 30, 2018 Total amounts presented in the consolidated statement of income $ (194 ) $ 1,940 $ (203 ) $ 120 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items 93 — 1 — Recognized on derivatives designated as hedging instruments (94 ) — — — Net income (expense) recognized on fair value hedges (1 ) — 1 — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income — (27 ) — — Net income (expense) recognized on cash flow hedges $ — $ (27 ) — — Six months ended June 30, 2017 Total amounts presented in the consolidated statement of income $ (142 ) $ 1,825 $ (124 ) $ 117 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items — — — 30 Recognized on derivatives designated as hedging instruments 32 — — (30 ) Net income (expense) recognized on fair value hedges 32 — — — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income (2 ) 20 — — Gains (losses) (before tax) recognized in income for hedge ineffectiveness — — — — Net income (expense) recognized on cash flow hedges $ (2 ) $ 20 — — (a) Prior period gain or loss amounts were not restated to conform to the new hedge accounting guidance adopted in 2018. Net investment hedges. We enter into foreign currency forward contracts to hedge our exposure to changes in the carrying value of our investments as a result of changes in the related foreign exchange rates. At June 30, 2018 , AOCI reflected unrecognized, after-tax gains totaling $44 million related to cumulative changes in the fair value of our net investment hedges, which offset the unrecognized, after-tax foreign currency losses on net investment balances. We did not exclude any portion of our hedging instruments from the assessment of hedge effectiveness during the six -month period ended June 30, 2018 . The following tables summarize the pre-tax net gains (losses) on our cash flow and net investment hedges for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 , and where they are recorded on the income statement. The table includes net gains (losses) recognized in OCI during the period and net gains (losses) reclassified from OCI into income during the current period. in millions Net Gains (Losses) Recognized in OCI Income Statement Location of Net Gains (Losses) Reclassified From OCI Into Income Net Gains (Losses) Reclassified From OCI Into Income (a) Net Gains (Losses) Recognized in Other Income (a) Three months ended June 30, 2018 Cash Flow Hedges Interest rate $ (58 ) Interest income — Loans $ (25 ) $ — Interest rate 2 Interest expense — Long-term debt 1 — Interest rate 1 Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts 10 Other Income — — Total $ (45 ) $ (24 ) $ — Three months ended June 30, 2017 Cash Flow Hedges Interest rate $ 22 Interest income — Loans $ 5 $ — Interest rate — Interest expense — Long-term debt (1 ) — Interest rate — Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts (7 ) Other Income — — Total $ 15 $ 4 $ — in millions Net Gains (Losses) Recognized in OCI Income Statement Location of Net Gains (Losses) Reclassified From OCI Into Income Net Gains (Losses) Reclassified From OCI Into Income (a) Net Gains (Losses) Recognized in Other Income (a) Six months ended June 30, 2018 Cash Flow Hedges Interest rate $ (146 ) Interest income — Loans $ (27 ) $ — Interest rate 4 Interest expense — Long-term debt — — Interest rate 1 Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts 10 Other Income — — Total $ (131 ) $ (27 ) $ — Six months ended June 30, 2017 Cash Flow Hedges Interest rate $ — Interest income — Loans $ 20 $ — Interest rate — Interest expense — Long-term debt (2 ) — Interest rate — Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts (10 ) Other Income — — Total $ (10 ) $ 18 $ — (a) Prior period gain or loss amounts were not restated to conform to the new hedge accounting guidance adopted in 2018. Nonhedging instruments The following tables summarize the pre-tax net gains (losses) on our derivatives that are not designated as hedging instruments for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 , and where they are recorded on the income statement. Three months ended June 30, 2018 Three months ended June 30, 2017 in millions Corporate services income Consumer mortgage income Other income Total Corporate services income Consumer mortgage income Other income Total NET GAINS (LOSSES) Interest rate $ 11 $ — $ — $ 11 $ 10 — $ (1 ) $ 9 Foreign exchange 11 — — 11 10 — — 10 Commodity 3 — — 3 1 — — 1 Credit — — (14 ) (14 ) — — (5 ) (5 ) Other — — 16 16 — $ 2 (10 ) (8 ) Total net gains (losses) $ 25 $ — $ 2 $ 27 $ 21 $ 2 $ (16 ) $ 7 Six months ended June 30, 2018 Six months ended June 30, 2017 in millions Corporate services income Consumer mortgage income Other income Total Corporate services income Consumer mortgage income Other income Total NET GAINS (LOSSES) Interest rate $ 20 $ — $ 2 $ 22 $ 16 — $ (2 ) $ 14 Foreign exchange 22 — — 22 21 — — 21 Commodity 6 — — 6 3 — — 3 Credit 2 — (19 ) (17 ) 1 — (10 ) (9 ) Other — — 12 12 — $ 1 (11 ) (10 ) Total net gains (losses) $ 50 $ — $ (5 ) $ 45 $ 41 $ 1 $ (23 ) $ 19 Counterparty Credit Risk We use several means to mitigate and manage exposure to credit risk on derivative contracts. We enter into bilateral collateral and master netting agreements that provide for the net settlement of all contracts with a single counterparty in the event of default. Additionally, we monitor counterparty credit risk exposure on each contract to determine appropriate limits on our total credit exposure across all product types. We review our collateral positions on a daily basis and exchange collateral with our counterparties in accordance with standard ISDA documentation, central clearing rules, and other related agreements. We hold collateral in the form of cash and highly rated securities issued by the U.S. Treasury, government-sponsored enterprises, or GNMA. Cash collateral of $127 million was included in derivative assets on the balance sheet at June 30, 2018 , compared to $23 million of cash collateral netted against derivative assets at December 31, 2017 . The cash collateral netted against derivative liabilities totaled $251 million at June 30, 2018 , and $150 million at December 31, 2017 . The following table summarizes the fair value of our derivative assets by type at the dates indicated. These assets represent our gross exposure to potential loss after taking into account the effects of bilateral collateral and master netting agreements and other means used to mitigate risk. in millions June 30, 2018 December 31, 2017 Interest rate $ 215 $ 401 Foreign exchange 66 77 Commodity 326 163 Credit — 1 Other 4 4 Derivative assets before collateral 611 646 Less: Related collateral (127 ) (23 ) Total derivative assets $ 738 $ 669 We enter into derivative transactions with two primary groups: broker-dealers and banks, and clients. Given that these groups have different economic characteristics, we have different methods for managing counterparty credit exposure and credit risk. We enter into transactions with broker-dealers and banks for various risk management purposes. At June 30, 2018 , we had gross exposure of $115 million to broker-dealers and banks. We had net exposure of $218 million after the application of master netting agreements and cash collateral, where such qualifying agreements exist. We had net exposure of $208 million after considering $10 million of additional collateral held in the form of securities. We enter into transactions with clients to accommodate their business needs. Due to the smaller size and magnitude of the individual contracts with clients, we generally do not exchange collateral in connection with these derivative transactions. To address the risk of default associated with the uncollateralized contracts, we have established a credit valuation adjustment (included in “accrued income and other assets”) in the amount of $3 million at June 30, 2018 , which we estimate to be the potential future losses on amounts due from client counterparties in the event of default. At June 30, 2018 , we had gross exposure of $582 million to client counterparties and other entities that are not broker-dealers or banks for derivatives that have associated master netting agreements. We had net exposure of $521 million on our derivatives with these counterparties after the application of master netting agreements, collateral, and the related reserve. Credit Derivatives We are a buyer and, under limited circumstances, may be a seller of credit protection through the credit derivative market. We purchase credit derivatives to manage the credit risk associated with swap obligations as well as exposures to debt securities. The following table summarizes the fair value of our credit derivatives purchased and sold by type as of June 30, 2018 , and December 31, 2017 . The fair value of credit derivatives presented below does not take into account the effects of bilateral collateral or master netting agreements. June 30, 2018 December 31, 2017 in millions Purchased Sold Net Purchased Sold Net Single-name credit default swaps $ (1 ) — $ (1 ) $ (1 ) — $ (1 ) Traded credit default swap indices (1 ) — (1 ) (2 ) — (2 ) Other — (1 ) (1 ) — — — Total credit derivatives $ (2 ) (1 ) $ (3 ) $ (3 ) — $ (3 ) The majority of transactions represented by the “other” category shown in the above table consist of risk participation agreements as described in Note 9. Derivatives and Hedging Activities of our 2017 Form 10-K under the heading “Credit Derivatives.” In addition, the other category includes credit default swap options in which we are given the right, but not the obligation, to purchase credit protection on a stated entity for a specified period of time. The following table provides information on the types of credit derivatives sold by us and held on the balance sheet at June 30, 2018 , and December 31, 2017 . The notional amount represents the maximum amount that the seller could be required to pay. The payment/performance risk assessment is based on the default probabilities for the underlying reference entities’ debt obligations using a Moody’s credit ratings matrix known as Moody’s “Idealized” Cumulative Default Rates. The payment/performance risk shown in the table represents a weighted-average of the default probabilities for all reference entities in the respective portfolios. These default probabilities are directly correlated to the probability that we will have to make a payment under the credit derivative contracts. June 30, 2018 December 31, 2017 dollars in millions Notional Amount Average Term (Years) Payment / Performance Risk Notional Amount Average Term (Years) Payment / Performance Risk Other $ 21 10.38 14.13 % $ 15 3.08 6.64 % Total credit derivatives sold $ 21 — — $ 15 — — Credit Risk Contingent Features We have entered into certain derivative contracts that require us to post collateral to the counterparties when these contracts are in a net liability position. The amount of collateral to be posted is based on the amount of the net liability and thresholds generally related to our long-term senior unsecured credit ratings with Moody’s and S&P. Collateral requirements also are based on minimum transfer amounts, which are specific to each Credit Support Annex (a component of the ISDA Master Agreement) that we have signed with the counterparties. In a limited number of instances, counterparties have the right to terminate their ISDA Master Agreements with us if our ratings fall below a certain level, usually investment-grade level (i.e., “Baa3” for Moody’s and “BBB-” for S&P). At June 30, 2018 , KeyBank’s rating was “ A3 ” with Moody’s and “ A- ” with S&P, and KeyCorp’s rating was “ Baa1 ” with Moody’s and “ BBB+ ” with S&P. As of June 30, 2018 , the aggregate fair value of all derivative contracts with credit risk contingent features (i.e., those containing collateral posting or termination provisions based on our ratings) held by KeyBank that were in a net liability position totaled $290 million , which was comprised of $143 million in derivative assets and $433 million in derivative liabilities. We had $270 million in cash and securities collateral posted to cover those positions as of June 30, 2018 . There were no derivative contracts with credit risk contingent features held by KeyCorp at June 30, 2018 . The following table summarizes the additional cash and securities collateral that KeyBank would have been required to deliver under the ISDA Master Agreements had the credit risk contingent features been triggered for the derivative contracts in a net liability position as of June 30, 2018 , and December 31, 2017 . The additional collateral amounts were calculated based on scenarios under which KeyBank’s ratings are downgraded one, two, or three ratings as of June 30, 2018 , and December 31, 2017 , and take into account all collateral already posted. A similar calculation was performed for KeyCorp, and no additional collateral would have been required as of June 30, 2018 , and December 31, 2017 . For more information about the credit ratings for KeyBank and KeyCorp, see the discussion under the heading “Factors affecting liquidity” in the section entitled “Liquidity risk management” in Item 2 of this report. June 30, 2018 December 31, 2017 in millions Moody’s S&P Moody’s S&P KeyBank’s long-term senior unsecured credit ratings A3 A- A3 A- One rating downgrade $ 2 $ 2 $ 2 $ 2 Two rating downgrades 2 2 2 2 Three rating downgrades 2 2 2 2 KeyBank’s long-term senior unsecured credit rating was four ratings above noninvestment grade at Moody’s and S&P as of June 30, 2018 , and December 31, 2017 . If KeyBank’s ratings had been downgraded below investment grade as of June 30, 2018 , or December 31, 2017 , payments of up to $3 million and $12 million , respectively, would have been required to either terminate the contracts or post additional collateral for those contracts in a net liability position, taking into account all collateral already posted. If KeyCorp’s ratings had been downgraded below investment grade as of June 30, 2018 , or December 31, 2017 , no

Mortgage Servicing Assets

Mortgage Servicing Assets	6 Months Ended
	Jun. 30, 2018
Servicing Asset [Abstract]
Mortgage Servicing Assets	8. Mortgage Servicing Assets We originate and periodically sell commercial and residential mortgage loans but continue to service those loans for the buyers. We also may purchase the right to service commercial mortgage loans for other lenders. We record a servicing asset if we purchase or retain the right to service loans in exchange for servicing fees that exceed the going market servicing rate and are considered more than adequate compensation for servicing. Additional information pertaining to the accounting for mortgage and other servicing assets is included in Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Servicing Assets” beginning on page 106 of our 2017 Form 10-K. Commercial Changes in the carrying amount of commercial mortgage servicing assets are summarized as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of period $ 435 $ 369 $ 412 $ 356 Servicing retained from loan sales 29 19 56 47 Purchases 12 7 33 14 Amortization (25 ) (22 ) (50 ) (44 ) Balance at end of period $ 451 $ 373 $ 451 $ 373 Fair value at end of period $ 646 $ 495 $ 646 $ 495 The fair value of commercial mortgage servicing assets is determined by calculating the present value of future cash flows associated with servicing the loans. This calculation uses a number of assumptions that are based on current market conditions. The range and weighted average of the significant unobservable inputs used to determine the fair value of our commercial mortgage servicing assets at June 30, 2018 , and June 30, 2017 , along with the valuation techniques, are shown in the following table: dollars in millions June 30, 2018 June 30, 2017 Valuation Technique Significant Unobservable Input Range (Weighted Average) Discounted cash flow Expected defaults 1.00 - 3.00% (1.17%) 1.00 - 3.00% (1.30%) Residual cash flows discount rate 7.00 - 15.00% (9.06%) 7.00 - 15.00% (8.80%) Escrow earn rate 2.40 - 3.82% (3.10%) 1.50 - 3.10% (2.50%) Servicing cost $150 - $38,500 ($1,431) $150 - $38,500 ($1,457) Loan assumption rate 0.00 - 3.00% (1.19%) 0.00 - 3.00% (1.24%) Percentage late 0.00 - 2.00% (.22%) 0.00 - 2.00% (.29%) If these economic assumptions change or prove incorrect, the fair value of commercial mortgage servicing assets may also change. Expected credit losses, escrow earning rates, and discount rates are critical to the valuation of commercial mortgage servicing assets. Estimates of these assumptions are based on how a market participant would view the respective rates, and reflect historical data associated with the commercial mortgage loans, industry trends, and other considerations. Actual rates may differ from those estimated due to changes in a variety of economic factors. A decrease in the value assigned to the escrow earning rates would cause a decrease in the fair value of our commercial mortgage servicing assets. An increase in the assumed default rates of commercial mortgage loans or an increase in the assigned discount rates would cause a decrease in the fair value of our commercial mortgage servicing assets. Prepayment activity on commercial serviced loans does not significantly affect the valuation of our commercial mortgage servicing assets. Unlike residential mortgages, commercial mortgages experience significantly lower prepayments due to certain contractual restrictions affecting the borrower’s ability to prepay the mortgage. The amortization of commercial servicing assets is determined in proportion to, and over the period of, the estimated net servicing income. The amortization of commercial servicing assets for each period, as shown in the table at the beginning of this note, is recorded as a reduction to contractual fee income. The contractual fee income from servicing commercial mortgage loans totaled $85 million for the six-month period ended June 30, 2018 , and $72 million for the six-month period ended June 30, 2017 . This fee income was offset by $50 million of amortization for the six-month period ended June 30, 2018 , and $44 million for the six-month period ended June 30, 2017 . Both the contractual fee income and the amortization are recorded, net, in “mortgage servicing fees” on the income statement. Residential Changes in the carrying amount of residential mortgage servicing assets are summarized as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of period $ 32 $ 29 $ 31 $ 28 Servicing retained from loan sales 3 1 5 3 Purchases — — — — Amortization (1 ) (1 ) (2 ) (2 ) Balance at end of period $ 34 $ 29 $ 34 $ 29 Fair value at end of period $ 43 $ 35 $ 43 $ 35 The fair value of mortgage servicing assets is determined by calculating the present value of future cash flows associated with servicing the loans. This calculation uses a number of assumptions that are based on current market conditions. The range and weighted-average of the significant unobservable inputs used to fair value our mortgage servicing assets at June 30, 2018 , and June 30, 2017 , along with the valuation techniques, are shown in the following table: dollars in millions June 30, 2018 June 30, 2017 Valuation Technique Significant Unobservable Input Range (Weighted Average) Discounted cash flow Prepayment speed 8.39 - 49.39% (9.17%) 7.85 - 21.72% (9.42%) Discount rate 8.50 - 11.00% (8.54%) 8.50 - 11.00% (8.55%) Servicing cost $76 - $4,385 ($82.38) $76 - $3,335 ($82.18) If these economic assumptions change or prove incorrect, the fair value of residential mortgage servicing assets may also change. Prepayment speed, discount rates, and servicing cost are critical to the valuation of servicing assets. Estimates of these assumptions are based on how a market participant would view the respective rates, and reflect historical data associated with the loans, industry trends, and other considerations. Actual rates may differ from those estimated due to changes in a variety of economic factors. An increase in the prepayment speed, assigned discount rates, and servicing cost assumptions would also cause a negative impact on the fair value of our residential mortgage servicing assets. The amortization of residential servicing assets is determined in proportion to, and over the period of, the estimated net residential servicing income. The amortization of servicing assets for June 30, 2018 , as shown in the table above, is recorded as a reduction to contractual fee income. The contractual fee income from servicing residential mortgage loans totaled $7 million for the six-month periods ended June 30, 2018 , and June 30, 2017 . This fee income was offset by $2 million of amortization for the six-month periods ended June 30, 2018 , and June 30, 2017 .

Variable Interest Entities

Variable Interest Entities	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	9. Variable Interest Entities A VIE is a partnership, limited liability company, trust, or other legal entity that meets any one of the following criteria: • The entity does not have sufficient equity to conduct its activities without additional subordinated financial support from another party. • The entity’s investors lack the power to direct the activities that most significantly affect the entity’s economic performance. • The entity’s equity at risk holders do not have the obligation to absorb losses or the right to receive residual returns. • The voting rights of some investors are not proportional to their economic interests in the entity, and substantially all of the entity’s activities involve, or are conducted on behalf of, investors with disproportionately few voting rights. Our significant VIEs are summarized below. We define a “significant interest” in a VIE as a subordinated interest that exposes us to a significant portion, but not the majority, of the VIE’s expected losses or residual returns, even though we do not have the power to direct the activities that most significantly affect the entity’s economic performance. LIHTC investments. Through KCDC, we have made investments directly and indirectly in LIHTC operating partnerships formed by third parties. As a limited partner in these operating partnerships, we are allocated tax credits and deductions associated with the underlying properties. We have determined that we are not the primary beneficiary of these investments because the general partners have the power to direct the activities that most significantly influence the economic performance of their respective partnerships and have the obligation to absorb expected losses and the right to receive residual returns. As we are not the primary beneficiary of these investments, we do not consolidate them. Our maximum exposure to loss in connection with these partnerships consists of our unamortized investment balance plus any unfunded equity commitments and tax credits claimed but subject to recapture. We had $1.3 billion of investments in LIHTC operating partnerships at both June 30, 2018 , and December 31, 2017 . These investments are recorded in “accrued income and other assets” on our balance sheet. We do not have any loss reserves recorded related to these investments because we believe the likelihood of any loss to be remote. For all legally binding, unfunded equity commitments, we increase our recognized investment and recognize a liability. As of June 30, 2018 , and December 31, 2017 , we had liabilities of $443 million and $476 million , respectively, related to investments in qualified affordable housing projects, which are recorded in “accrued expenses and other liabilities” on our balance sheet. We continue to invest in these LIHTC operating partnerships. The assets and liabilities presented in the table below convey the size of KCDC’s direct and indirect investments at June 30, 2018 , and December 31, 2017 . As these investments represent unconsolidated VIEs, the assets and liabilities of the investments themselves are not recorded on our balance sheet. Unconsolidated VIEs in millions Total Assets Total Liabilities Maximum Exposure to Loss June 30, 2018 LIHTC investments $ 6,176 $ 2,971 $ 1,583 December 31, 2017 LIHTC investments $ 6,003 $ 2,943 $ 1,561 We amortize our LIHTC investments over the period that we expect to receive the tax benefits. During the first six months of 2018 , we recognized $83 million of amortization and $81 million of tax credits associated with these investments within “income taxes” on our income statement. During the first six months of 2017 , we recognized $81 million of amortization and $78 million of tax credits associated with these investments within “income taxes” on our income statement. Principal investments. Through our principal investing entities, we have made investments in private equity funds engaged in venture- and growth-oriented investing. As a limited partner to these funds, we record these investments at fair value and receive distributions from the funds in accordance with the funds’ partnership agreements. We are not the primary beneficiary of these investments as we do not hold the power to direct the activities that most significantly affect the funds’ economic performance. Such power rests with the funds’ general partners. In addition, we have neither the obligation to absorb the funds’ expected losses nor the right to receive their residual returns. Our voting rights are also disproportionate to our economic interests, and substantially all of the funds’ activities are conducted on behalf of investors with disproportionately few voting rights. Because we are not the primary beneficiary of these investments, we do not consolidate them. Our maximum exposure to loss associated with indirect principal investments consists of the investments’ fair value plus any unfunded equity commitments. The fair value of our indirect principal investments totaled $109 million and $124 million at June 30, 2018 , and December 31, 2017 , respectively. These investments are recorded in “other investments” on our balance sheet. Additional information on indirect principal investments is provided in Note 5 (“ Fair Value Measurements ”). The table below reflects the size of the private equity funds in which we were invested as well as our maximum exposure to loss in connection with these investments at June 30, 2018 and December 31, 2017 . Unconsolidated VIEs in millions Total Assets Total Liabilities Maximum Exposure to Loss June 30, 2018 Indirect investments $ 22,367 $ 426 $ 137 December 31, 2017 Indirect investments $ 26,817 $ 292 $ 153 Through our principal investing entities, we have formed and funded operating entities that provide management and other related services to our investment company funds, which directly invest in portfolio companies. In return for providing services to our direct investment funds, these entities’ receive a minority equity interest in the funds. This minority equity ownership is recorded at fair value on the entities’ financial statements. Additional information on our direct principal investments is provided in Note 5 (“ Fair Value Measurements ”). While other equity investors manage the daily operations of these entities, we retain the power, through voting rights, to direct the activities of the entities that most significantly affect their economic performance. In addition, we have the obligation to absorb losses and the right to receive residual returns that could potentially be significant to these entities. As a result, we have determined that we are the primary beneficiary of these funds and have consolidated them since formation. The entities had no assets at June 30, 2018 , that can only be used to settle the entities’ obligations, and $4 million of such assets at December 31, 2017 . These assets are recorded in “cash and due from banks” and “accrued income and other assets” on our balance sheet. The entities had no liabilities at June 30, 2018 , and December 31, 2017 , and other equity investors have no recourse to our general credit. Other unconsolidated VIEs. We are involved with other various entities in the normal course of business which we have determined to be VIEs. We have determined that we are not the primary beneficiary of these VIEs because we do not have the power to direct the activities that most significantly impact their economic performance. Our assets associated with these unconsolidated VIEs totaled $209 million at June 30, 2018 , and $230 million at December 31, 2017 . These assets are recorded in “accrued income and other assets,” “other investments,” “securities available for sale”, and “loans, net of unearned income” on our balance sheet. We had liabilities totaling $4 million associated with these unconsolidated VIEs at both June 30, 2018 , and December 31, 2017 . These liabilities are recorded in “accrued expenses and other liabilities” on our balance sheet. We have excluded certain transactions with unconsolidated VIEs from the balances above where we determine our continuing involvement is not significant. In addition, where we only have a lending arrangement in the normal course of business with unconsolidated VIEs we present the balances related to the lending arrangements in Note 4 (“ Asset Quality

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes Bipartisan Budget Act of 2018 On February 9, 2018, the Bipartisan Budget Act (“BBA”) of 2018 was signed into law. The BBA includes a retroactive one year tax extenders package back to January 1, 2017, that reinstated several energy investment tax credits that had expired on December 31, 2016. Due to these retroactive provisions, Key recognized additional net investment tax credits in the first quarter of 2018 of $14 million , or a 2.8% reduction to our income tax provision, for energy tax credit transactions entered into during 2017. TCJ Act On December 22, 2017, the TCJ Act was signed into law. This comprehensive tax legislation provides for significant changes to the U.S. Internal Revenue Code of 1986, as amended, that impact corporate taxation requirements, such as the reduction in the federal corporate income tax rate from 35% to 21% effective January 1, 2018. The TCJ Act retains the low-income housing and research and development credits and repeals the corporate alternative minimum tax. Other relevant corporate changes include earlier recognition of certain revenue; accelerating expensing of investments in tangible property, including leasing assets; and limiting several deductions such as FDIC premiums, certain executive compensation, and meals and entertainment expenses. Key was required to re-value certain tax-related assets under the provisions of the TCJ Act at December 31, 2017. Under current U.S. GAAP, deferred tax assets and liabilities are to be adjusted for the effect of a change in tax laws or rates with the effect included in income from continuing operations in the reporting period that includes the enactment date. The tax-related assets consist primarily of deferred tax assets and liabilities and investments in low-income housing transactions. Due to the close proximity of our year end to the date the TCJ Act was signed into law, we estimated the impact of the income tax effects as of December 31, 2017, based upon currently available information which resulted in a reduction to our net income of $161 million . The significant components of this reduction included a $14 million reduction in our investments in certain low-income housing that is reflected in other expenses and a $147 million , or 7.6% , increase in our income tax provision for the twelve months ended December 31, 2017, due to the reduction to our net deferred tax asset and related actions. This reduction is primarily the result of the lower federal corporate income tax rate, is based on information available at this time, and is subject to change due to a variety of factors, including among others: (i) completion of Key’s 2017 federal and state income tax returns, and (ii) management’s further assessment of the TCJ Act and related regulatory guidance. Adjustments may be made in future periods to these estimates as we continue to obtain, prepare and analyze information about facts and circumstances that existed as of the enactment date that, if known, would have affected the income tax effects reported as provisional amounts. Key expects to finalize this impact in the quarter ending September 30, 2018. The accounting for the changes in tax law resulted in stranded tax effects within accumulated other comprehensive income for items that were originally recognized in other comprehensive income rather than in net income. The FASB issued an accounting standard update allowing companies to reclassify stranded tax effects resulting from the TCJ Act from accumulated other comprehensive income to retained earnings. We early adopted this guidance during the quarter ended December 31, 2017, and utilizing the portfolio method reclassified $141 million from accumulated other comprehensive income to retained earnings to eliminate the stranded tax effects. Income Tax Provision In accordance with the applicable accounting guidance, the principal method established for computing the provision for income taxes in interim periods requires us to make our best estimate of the effective tax rate expected to be applicable for the full year. This estimated effective tax rate is then applied to interim consolidated pre-tax operating income to determine the interim provision for income taxes. The effective tax rate, which is the provision for income taxes as a percentage of income from continuing operations before income taxes, was 17.6% for the second quarter of 2018 and 28.0% for the second quarter of 2017 . The effective tax rates are below our combined federal and state statutory tax rate of 23.7% for the second quarter of 2018 and 37.2% for the second quarter of 2017 , primarily due to income from investments in tax-advantaged assets such as corporate-owned life insurance and credits associated with renewable energy and low-income housing investments. The effective tax rates for the three months ended June 30, 2018 , and June 30, 2017 , were affected by net discrete income tax expense of .5% and net discrete income tax benefits of .5% , respectively. Deferred Tax Asset At June 30, 2018 , from continuing operations we had a net deferred tax asset of $389 million , compared to a net deferred tax asset of $320 million at December 31, 2017 , included in “accrued income and other assets” on the balance sheet. To determine the amount of deferred tax assets that are more likely than not to be realized, and therefore recorded, we conduct a quarterly assessment of all available evidence. This evidence includes, but is not limited to, taxable income in prior periods, projected future taxable income, and projected future reversals of deferred tax items. These assessments involve a degree of subjectivity and may undergo change. Based on these criteria, we had a valuation allowance of $11 million at June 30, 2018 , and $15 million at December 31, 2017 . The valuation allowance is associated with certain state net operating loss carryforwards, state credit carryforwards, and federal and state capital loss carryforwards. Unrecognized Tax Benefits As permitted under the applicable accounting guidance for income taxes, it is our policy to recognize interest and penalties related to unrecognized tax benefits in “income tax expense.” At June 30, 2018 , Key’s unrecognized tax benefits were $38 million . Pre-1988 Bank Reserves Acquired in a Business Combination Retained earnings of KeyBank included approximately $92 million

Acquisition, Divestiture, and D

Acquisition, Divestiture, and Discontinued Operations	6 Months Ended
	Jun. 30, 2018
Business Combinations [Abstract]
Acquisition, Divestiture, and Discontinued Operations	11. Acquisitions, Divestiture, and Discontinued Operations Acquisitions Cain Brothers & Company, LLC. On October 2, 2017, KBCM acquired all outstanding interests in Cain Brothers, a healthcare-focused investment banking and public finance firm. This acquisition expands KBCM’s investment banking group in the healthcare vertical by adding distinctive capabilities and broadening KBCM’s existing healthcare investment banking network. The acquisition was accounted for as a business combination. As a result of the acquisition, Key recognized identifiable intangible assets with a fair value of $30 million and goodwill of $53 million , which are deductible for tax purposes. The valuation of the acquired assets and liabilities of Cain Brothers was final at March 31, 2018. HelloWallet Holdings, Inc. On July 1, 2017, KeyBank acquired all of the outstanding capital stock of HelloWallet Holdings, Inc., the sole owner of HelloWallet, LLC, a digital financial wellness company. Key’s retail banking franchise is leveraging HelloWallet’s technology to provide data-driven insights to clients, allowing clients to better understand and improve their personal finances. The acquisition was accounted for as a business combination. As a result of the acquisition, Key recognized identifiable intangible assets with a fair value of $12 million , comprised primarily of propriety software, and goodwill of $17 million , which are not deductible for tax purposes. The valuation of the acquired assets and liabilities of HelloWallet was final at March 31, 2018. Key Merchant Services, LLC. On June 30, 2017, KeyBank (consolidated) acquired an additional 51% interest in Key Merchant Services, LLC (“KMS”), increasing our ownership interest from 49% to 100% . This acquisition enables us to grow our merchant services business and enhance our merchant product offerings. This transaction is accounted for as a business combination achieved in stages. Prior to the acquisition, KMS was operated as a merchant services joint venture and accounted for as an equity method investment in our consolidated financial statements. As of June 30, 2017, the provisional estimated fair value of our equity interest in KMS immediately before the acquisition was $74 million . The fair value of our previously held equity interest was measured using discounted cash flow modeling that incorporates an appropriate risk premium and forecast earnings information. On June 30, 2017, we recognized a provisional non-cash holding gain of $64 million for the difference between the fair value and the book value of our previously held equity interest. In the third quarter of 2017, we recognized a measurement-period adjustment of $5 million to reduce the provisional estimated fair value of our equity interest immediately before the acquisition to $69 million , which reduced the total non-cash holding gain to $59 million . The initial gain and subsequent adjustment were included in “other income” on the income statement for the three months ended September 30, 2017. Upon acquisition, we recorded estimated identifiable intangible assets of $95 million and goodwill of less than $1 million . In the third quarter of 2017, we recognized a measurement-period adjustment of $10 million to reduce the fair value of acquired intangible assets to $85 million . In the fourth quarter of 2017, we recognized a measurement period adjustment increasing deferred tax assets and decreasing goodwill by $2 million . In aggregate, the measurement-period adjustments recognized as of December 31, 2017, increased goodwill recorded in connection with the KMS acquisition to $4 million . The valuation of the acquired assets and liabilities of Key Merchant Services, LLC was final at June 30, 2018. Divestiture Key Insurance & Benefits Services, Inc. On March 29, 2018, we announced that we had entered into a definitive agreement to sell Key Insurance & Benefits Services, Inc. to USI Insurance Services. We acquired Key Insurance & Benefits Services, Inc. as a part of the 2016 merger with First Niagara. We completed the sale to USI Insurance Services on May 4, 2018. At the close of the sale, we recognized a $73 million net gain on sale. Discontinued operations Discontinued operations primarily includes our government-guaranteed education lending business. At June 30, 2018 , and December 31, 2017 , approximately $1.2 billion and $1.3 billion

Securities Financing Activities

Securities Financing Activities	6 Months Ended
	Jun. 30, 2018
Banking and Thrift [Abstract]
Securities Financing Activities	12. Securities Financing Activities We enter into repurchase agreements to finance overnight customer sweep deposits. We also enter into repurchase and reverse repurchase agreements to settle other securities obligations. We account for these securities financing agreements as collateralized financing transactions. Repurchase and reverse repurchase agreements are recorded on the balance sheet at the amounts for which the securities will be subsequently sold or repurchased. Securities borrowed transactions are recorded on the balance sheet at the amounts of cash collateral advanced. While our securities financing agreements incorporate a right of set off, the assets and liabilities are reported on a gross basis. Reverse repurchase agreements and securities borrowed transactions are included in “short-term investments” on the balance sheet; repurchase agreements are included in “federal funds purchased and securities sold under repurchase agreements.” Additional information regarding our securities financing activities, including risk management activities, is provided in Note 16. Securities Financing Activities beginning on page 160 of our 2017 Form 10-K. The following table summarizes our securities financing agreements at June 30, 2018 , and December 31, 2017 : June 30, 2018 December 31, 2017 in millions Gross Amount Presented in Balance Sheet Netting Adjustments (a) Collateral (b) Net Amounts Gross Amount Presented in Balance Sheet Netting Adjustments (a) Collateral (b) Net Amounts Offsetting of financial assets: Reverse repurchase agreements $ 11 $ (11 ) $ — — $ 3 $ (3 ) — — Total $ 11 $ (11 ) $ — — $ 3 $ (3 ) — — Offsetting of financial liabilities: Repurchase agreements (c) $ 266 $ (14 ) $ (252 ) — $ 374 $ (4 ) $ (370 ) — Total $ 266 $ (14 ) $ (252 ) — $ 374 $ (4 ) $ (370 ) — (a) Netting adjustments take into account the impact of master netting agreements that allow us to settle with a single counterparty on a net basis. (b) These adjustments take into account the impact of bilateral collateral agreements that allow us to offset the net positions with the related collateral. The application of collateral cannot reduce the net position below zero. Therefore, excess collateral, if any, is not reflected above. (c) Repurchase agreements are collateralized by mortgaged-backed agency securities and are contracted on an overnight or continuous basis. As of June 30, 2018 , the carrying amount of assets pledged as collateral against repurchase agreements totaled $409 million . Assets pledged as collateral are reported in “securities available for sale” and “held-to-maturity securities” on our balance sheet. At June 30, 2018 , the liabilities associated with collateral pledged were solely comprised of customer sweep financing activity and had a carrying value of $252 million

Employee Benefits

Employee Benefits	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Employee Benefits	13. Employee Benefits Pension Plans Effective December 31, 2009, we amended our cash balance pension plan and other defined benefit plans to freeze all benefit accruals and close the plans to new employees. We will continue to credit participants’ existing account balances for interest until they receive their plan benefits. We changed certain pension plan assumptions after freezing the plans. The components of net pension cost (benefit) for all funded and unfunded plans are as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Interest cost on PBO $ 10 $ 12 $ 20 $ 24 Expected return on plan assets (13 ) (17 ) (26 ) (34 ) Amortization of losses 4 4 8 8 Net pension cost $ 1 $ (1 ) $ 2 $ (2 ) Other Postretirement Benefit Plans We sponsor a retiree healthcare plan in which all employees age 55 with five years of service (or employees age 50 with 15 years of service who are terminated under conditions that entitle them to a severance benefit) are eligible to participate. Participant contributions are adjusted annually. Key may provide a subsidy toward the cost of coverage for certain employees hired before 2001 with a minimum of 15 years of service at the time of termination. We use a separate VEBA trust to fund the retiree healthcare plan.

Trust Preferred Securities Issu

Trust Preferred Securities Issued by Unconsolidated Subsidiaries	6 Months Ended
	Jun. 30, 2018
Banking and Thrift [Abstract]
Trust Preferred Securities Issued by Unconsolidated Subsidiaries	14. Trust Preferred Securities Issued by Unconsolidated Subsidiaries We own the outstanding common stock of business trusts formed by us that issued corporation-obligated, mandatorily redeemable, trust preferred securities. The trusts used the proceeds from the issuance of their trust preferred securities and common stock to buy debentures issued by KeyCorp. These debentures are the trusts’ only assets; the interest payments from the debentures finance the distributions paid on the mandatorily redeemable trust preferred securities. The outstanding common stock of these business trusts is recorded in “other investments” on our balance sheet. We unconditionally guarantee the following payments or distributions on behalf of the trusts: • required distributions on the trust preferred securities; • the redemption price when a capital security is redeemed; and • the amounts due if a trust is liquidated or terminated. The Regulatory Capital Rules, discussed in “Supervision and regulation” in Item 2 of this report, require us to treat our mandatorily redeemable trust preferred securities as Tier 2 capital. The trust preferred securities, common stock, and related debentures are summarized as follows: dollars in millions Trust Preferred Securities, Net of Discount (a) Common Stock Principal Amount of Debentures, Net of Discount (b) Interest Rate of Trust Preferred Securities and Debentures (c) Maturity of Trust Preferred Securities and Debentures June 30, 2018 KeyCorp Capital I $ 155 $ 6 $ 161 3.052 % 2028 KeyCorp Capital II 101 4 105 6.875 2029 KeyCorp Capital III 130 4 134 7.750 2029 HNC Statutory Trust III 18 1 19 3.730 2035 Willow Grove Statutory Trust I 18 1 19 3.651 2036 HNC Statutory Trust IV 16 1 17 3.639 2037 Westbank Capital Trust II 7 — 7 4.515 2034 Westbank Capital Trust III 7 — 7 4.515 2034 Total $ 452 $ 17 $ 469 5.374 % — December 31, 2017 $ 463 $ 17 $ 480 4.977 % — (a) The trust preferred securities must be redeemed when the related debentures mature, or earlier if provided in the governing indenture. Each issue of trust preferred securities carries an interest rate identical to that of the related debenture. Certain trust preferred securities include basis adjustments related to fair value hedges totaling $44 million at June 30, 2018 , and $55 million at December 31, 2017 . See Note 7 (“ Derivatives and Hedging Activities ”) for an explanation of fair value hedges. (b) We have the right to redeem these debentures. If the debentures purchased by KeyCorp Capital I, HNC Statutory Trust III, Willow Grove Statutory Trust I, HNC Statutory Trust IV, Westbank Capital Trust II, or Westbank Capital Trust III are redeemed before they mature, the redemption price will be the principal amount, plus any accrued but unpaid interest. If the debentures purchased by KeyCorp Capital II or KeyCorp Capital III are redeemed before they mature, the redemption price will be the greater of: (i) the principal amount, plus any accrued but unpaid interest, or (ii) the sum of the present values of principal and interest payments discounted at the Treasury Rate (as defined in the applicable indenture), plus 20 basis points for KeyCorp Capital II or 25 basis points for KeyCorp Capital III, or 50 basis points in the case of redemption upon either a tax or a capital treatment event for either KeyCorp Capital II or KeyCorp Capital III, plus any accrued but unpaid interest. The principal amount of certain debentures includes basis adjustments related to fair value hedges totaling $44 million at June 30, 2018 , and $55 million at December 31, 2017 . See Note 7 (“ Derivatives and Hedging Activities ”) for an explanation of fair value hedges. The principal amount of debentures, net of discounts, is included in “long-term debt” on the balance sheet. (c)

Contingent Liabilities and Guar

Contingent Liabilities and Guarantees	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingent Liabilities and Guarantees	15. Contingent Liabilities and Guarantees Legal Proceedings Litigation. From time to time, in the ordinary course of business, we and our subsidiaries are subject to various litigation, investigations, and administrative proceedings. Private, civil litigations may range from individual actions involving a single plaintiff to putative class action lawsuits with potentially thousands of class members. Investigations may involve both formal and informal proceedings, by both government agencies and self-regulatory bodies. These matters may involve claims for substantial monetary relief. At times, these matters may present novel claims or legal theories. Due to the complex nature of these various other matters, it may be years before some matters are resolved. While it is impossible to ascertain the ultimate resolution or range of financial liability, based on information presently known to us, we do not believe there is any matter to which we are a party, or involving any of our properties that, individually or in the aggregate, would reasonably be expected to have a material adverse effect on our financial condition. We continually monitor and reassess the potential materiality of these litigation matters. We note, however, that in light of the inherent uncertainty in legal proceedings there can be no assurance that the ultimate resolution will not exceed established reserves. As a result, the outcome of a particular matter, or a combination of matters, may be material to our results of operations for a particular period, depending upon the size of the loss or our income for that particular period. Guarantees We are a guarantor in various agreements with third parties. The following table shows the types of guarantees that we had outstanding at June 30, 2018 . Information pertaining to the basis for determining the liabilities recorded in connection with these guarantees is included in Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Guarantees” beginning on page 108 of our 2017 Form 10-K. June 30, 2018 Maximum Potential Undiscounted Future Payments Liability Recorded in millions Financial guarantees: Standby letters of credit $ 3,124 $ 72 Recourse agreement with FNMA 3,547 7 Residential mortgage reserve 1,454 6 Return guarantee agreement with LIHTC investors 3 3 Written put options (a) 2,764 88 Total $ 10,892 $ 176 (a) The maximum potential undiscounted future payments represent notional amounts of derivatives qualifying as guarantees. We determine the payment/performance risk associated with each type of guarantee described below based on the probability that we could be required to make the maximum potential undiscounted future payments shown in the preceding table. We use a scale of low ( 0% to 30% probability of payment), moderate (greater than 30% to 70% probability of payment), or high (greater than 70% probability of payment) to assess the payment/performance risk, and have determined that the payment/performance risk associated with each type of guarantee outstanding at June 30, 2018 , is low. Standby letters of credit. KeyBank issues standby letters of credit to address clients’ financing needs. These instruments obligate us to pay a specified third party when a client fails to repay an outstanding loan or debt instrument or fails to perform some contractual nonfinancial obligation. Any amounts drawn under standby letters of credit are treated as loans to the client; they bear interest (generally at variable rates) and pose the same credit risk to us as a loan. At June 30, 2018 , our standby letters of credit had a remaining weighted-average life of two years , with remaining actual lives ranging from less than one year to as many as 16 years . Recourse agreement with FNMA. We participate as a lender in the FNMA Delegated Underwriting and Servicing program. FNMA delegates responsibility for originating, underwriting, and servicing mortgages, and we assume a limited portion of the risk of loss during the remaining term on each commercial mortgage loan that we sell to FNMA. We maintain a reserve for such potential losses in an amount that we believe approximates the fair value of our liability. At June 30, 2018 , the outstanding commercial mortgage loans in this program had a weighted-average remaining term of 7.9 years , and the unpaid principal balance outstanding of loans sold by us as a participant was $12.5 billion . The maximum potential amount of undiscounted future payments that we could be required to make under this program, as shown in the preceding table, is equal to approximately 28% of the principal balance of loans outstanding at June 30, 2018 . If we are required to make a payment, we would have an interest in the collateral underlying the related commercial mortgage loan; any loss we incur could be offset by the amount of any recovery from the collateral. Residential Mortgage Banking. We often originate and sell residential mortgage loans with servicing retained. Our loan sales activity is generally conducted through loan sales in a secondary market sponsored by FNMA and FHLMC. Subsequent to the sale of mortgage loans, we do not typically retain any interest in the underlying loans except through our relationship as the servicer of the loans. As is customary in the mortgage banking industry, we, or banks we have acquired, have made certain representations and warranties related to the sale of residential mortgage loans (including loans sold with servicing released) and to the performance of our obligations as servicer. The breach of any such representations or warranties could result in losses for us. Our maximum exposure to loss is equal to the outstanding principal balance of the sold loans; however, any loss would be reduced by any payments received on the loans or through the sale of collateral. At June 30, 2018 , the outstanding residential mortgage loans in this program had a weighted-average LTV ratio of 72% , and the unpaid principal balance outstanding of loans sold by us was $4.8 billion . The risk assessment is low for the residential mortgage product. The maximum potential amount of undiscounted future payments that we could be required to make under this program, as shown in the preceding table, is equal to approximately 30% of the principal balance of loans outstanding at June 30, 2018 . Our liability for estimated repurchase obligations on loans sold, which is included in other liabilities on our balance sheet, was $6 million at June 30, 2018 . Return guarantee agreement with LIHTC investors. KAHC, a subsidiary of KeyBank, offered limited partnership interests to qualified investors. Partnerships formed by KAHC invested in low-income residential rental properties that qualify for federal low-income housing tax credits under Section 42 of the Internal Revenue Code. In certain partnerships, investors paid a fee to KAHC for a guaranteed return that is based on the financial performance of the property and the property’s confirmed LIHTC status throughout a 15 -year compliance period. Typically, KAHC fulfills these guaranteed returns by distributing tax credits and deductions associated with the specific properties. If KAHC defaults on its obligation to provide the guaranteed return, KeyBank is obligated to make any necessary payments to investors. No recourse or collateral is available to offset our guarantee obligation other than the underlying income streams from the properties and the residual value of the operating partnership interests. As shown in the previous table, KAHC maintained a reserve in the amount of $3 million at June 30, 2018 , which is sufficient to cover estimated future obligations under the guarantees. The maximum exposure to loss reflected in the table represents undiscounted future payments due to investors for the return on and of their investments. These guarantees have expiration dates that extend through 2018 , but KAHC has not formed any new partnerships under this program since October 2003. Additional information regarding these partnerships is included in Note 9 (“ Variable Interest Entities ”). Written put options. In the ordinary course of business, we “write” put options for clients that wish to mitigate their exposure to changes in interest rates and commodity prices. At June 30, 2018 , our written put options had an average life of three years . These instruments are considered to be guarantees, as we are required to make payments to the counterparty (the client) based on changes in an underlying variable that is related to an asset, a liability, or an equity security that the client holds. We are obligated to pay the client if the applicable benchmark interest rate or commodity price is above or below a specified level (known as the “strike rate”). These written put options are accounted for as derivatives at fair value, as further discussed in Note 7 (“ Derivatives and Hedging Activities ”). We mitigate our potential future payment obligations by entering into offsetting positions with third parties. Written put options where the counterparty is a broker-dealer or bank are accounted for as derivatives at fair value but are not considered guarantees since these counterparties typically do not hold the underlying instruments. In addition, we are a purchaser and seller of credit derivatives, which are further discussed in Note 7 (“ Derivatives and Hedging Activities ”). Default guarantees. Some lines of business participate in guarantees that obligate us to perform if the debtor (typically a client) fails to satisfy all of its payment obligations to third parties. We generally undertake these guarantees for one of two possible reasons: (i) either the risk profile of the debtor should provide an investment return, or (ii) we are supporting our underlying investment in the debtor. We do not hold collateral for the default guarantees. If we were required to make a payment under a guarantee, we would receive a pro rata share should the third party collect some or all of the amounts due from the debtor. At June 30, 2018 , we had less than $1 million of default guarantees. Other Off-Balance Sheet Risk Other off-balance sheet risk stems from financial instruments that do not meet the definition of a guarantee as specified in the applicable accounting guidance, and from other relationships. Indemnifications provided in the ordinary course of business. We provide certain indemnifications, primarily through representations and warranties in contracts that we execute in the ordinary course of business in connection with loan and lease sales and other ongoing activities, as well as in connection with purchases and sales of businesses. We maintain reserves, when appropriate, with respect to liability that reasonably could arise as a result of these indemnities. Intercompany guarantees.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Accumulated Other Comprehensive Income	16. Accumulated Other Comprehensive Income Our changes in AOCI for the three and six months ended June 30, 2018 , and June 30, 2017 , are as follows: in millions Unrealized gains (losses) on securities available for sale Unrealized gains (losses) on derivative financial instruments Foreign currency translation adjustment Net pension and postretirement benefit costs Total Balance at December 31, 2017 $ (311 ) $ (86 ) $ 9 $ (391 ) $ (779 ) Other comprehensive income before reclassification, net of income taxes (216 ) (100 ) (11 ) — (327 ) Amounts reclassified from AOCI, net of income taxes (a) — 20 — 6 26 Other amounts reclassified from AOCI, net of income taxes — — (5 ) — (5 ) Net current-period other comprehensive income, net of income taxes (216 ) (80 ) (16 ) 6 (306 ) Balance at June 30, 2018 $ (527 ) $ (166 ) $ (7 ) $ (385 ) $ (1,085 ) Balance at March 31, 2018 $ (461 ) $ (149 ) $ 7 $ (388 ) $ (991 ) Other comprehensive income before reclassification, net of income taxes (66 ) (35 ) (9 ) — (110 ) Amounts reclassified from AOCI, net of income taxes (a) — 18 — 3 21 Other amounts reclassified from AOCI, net of income taxes — — (5 ) — (5 ) Net current-period other comprehensive income, net of income taxes (66 ) (17 ) (14 ) 3 (94 ) Balance at June 30, 2018 $ (527 ) $ (166 ) $ (7 ) $ (385 ) $ (1,085 ) Balance at December 31, 2016 $ (185 ) $ (14 ) $ (3 ) $ (339 ) $ (541 ) Other comprehensive income before reclassification, net of income taxes 40 (6 ) 7 — 41 Amounts reclassified from AOCI, net of income taxes (a) — (11 ) — 5 (6 ) Net current-period other comprehensive income, net of income taxes 40 (17 ) 7 5 35 Balance at June 30, 2017 $ (145 ) $ (31 ) $ 4 $ (334 ) $ (506 ) Balance at March 31, 2017 (179 ) $ (38 ) $ (2 ) $ (335 ) $ (554 ) Other comprehensive income before reclassification, net of income taxes 34 9 6 (1 ) 48 Amounts reclassified from AOC, net of income taxes (a) — (2 ) — 2 — Net current-period other comprehensive income, net of income taxes 34 7 6 1 48 Balance at June 30, 2017 $ (145 ) $ (31 ) $ 4 $ (334 ) $ (506 ) (a) See table below for details about these reclassifications. Our reclassifications out of AOCI for the three and six months ended June 30, 2018 , and June 30, 2017 , are as follows: Six months ended June 30, Affected Line Item in the Statement Where Net Income is Presented in millions 2018 2017 Unrealized gains (losses) on derivative financial instruments Interest rate $ (27 ) $ 20 Interest income — Loans Interest rate — (2 ) Interest expense — Long-term debt (27 ) 18 Income (loss) from continuing operations before income taxes (7 ) 7 Income taxes $ (20 ) $ 11 Income (loss) from continuing operations Net pension and postretirement benefit costs Amortization of losses $ (8 ) $ (8 ) Personnel expense (8 ) (8 ) Income (loss) from continuing operations before income taxes (2 ) (3 ) Income taxes $ (6 ) $ (5 ) Income (loss) from continuing operations Three months ended June 30, Affected Line Item in the Statement Where Net Income is Presented in millions 2018 2017 Unrealized gains (losses) on derivative financial instruments Interest rate $ (25 ) $ 5 Interest income — Loans Interest rate 1 (1 ) Interest expense — Long-term debt (24 ) 4 Income (loss) from continuing operations before income taxes (6 ) 2 Income taxes $ (18 ) 2 Income (loss) from continuing operations Net pension and postretirement benefit costs Amortization of losses $ (4 ) (4 ) Personnel expense (4 ) (4 ) Income (loss) from continuing operations before income taxes (1 ) (2 ) Income taxes $ (3 ) $ (2 ) Income (loss) from continuing operations

Shareholders' Equity

Shareholders' Equity	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Shareholder' Equity	17. Shareholders' Equity Comprehensive Capital Plan As previously reported and as authorized by the Board and pursuant to our 2017 capital plan (which was effective through the second quarter of 2018) submitted and not objected to by the Federal Reserve, we had authority to repurchase up to $800 million of our Common Shares. We completed $126 million of Common Share repurchases, including $123 million of Common Share repurchases in the open market and $3 million of Common Share repurchases related to employee equity compensation programs, in the second quarter of 2018 under this authorization. Consistent with our 2017 capital plan, the Board declared a quarterly dividend of $.12 per Common Share for the second quarter of 2018 . On June 28, 2018, the Federal Reserve announced that it did not object to our 2018 capital plan submitted as part of the annual CCAR process. Share repurchases of up to $1.225 billion were included in the 2018 capital plan, which is effective from the third quarter of 2018 through the second quarter of 2019. Also included was a dividend increase to $.17 per Common Share which was approved and declared by our Board on July 11, 2018, for the third quarter of 2018. Preferred Stock We have $525 million of depositary shares, each representing a 1/25 th ownership interest in a share of our Fixed-to-Floating Rate Perpetual Noncumulative Series D Preferred Stock outstanding at June 30, 2018 , and December 31, 2017 . Our Series D Preferred Stock has a $1 par value with a $25,000 liquidation preference (equivalent to $1,000 per depositary share). There are 21,000 shares of Series D Preferred Stock authorized and outstanding at June 30, 2018 , and December 31, 2017 . We made payments of $12.50 per depositary share on the depositary shares related to our Series D Preferred Stock during the second quarter of 2018 . We have $500 million of depositary shares, each representing a 1/40 th ownership interest in a share of our Fixed-to-Floating Rate Perpetual Noncumulative Series E Preferred Stock outstanding at June 30, 2018 , and December 31, 2017 . Our Series E Preferred Stock has a $1 par value with a $1,000 liquidation preference (equivalent to $25 per depositary share). There are 500,000 shares of Series E Preferred Stock authorized and outstanding at June 30, 2018 , and December 31, 2017 . We made payments of $.382813 per depositary share on the depositary shares related to our Series E Preferred Stock during the second quarter of 2018 . On July 30, 2018, we issued $425 million of depositary shares, each representing a 1/40 th ownership interest in a share of our Fixed Rate Perpetual Noncumulative Series F Preferred Stock. Our Series F Preferred Stock has a $1 par value with a $1,000 liquidation preference (equivalent to $25

Line of Business Results

Line of Business Results	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Line of Business Results	18. Line of Business Results The specific lines of business that constitute each of the major business segments (operating segments) align with how management reviews performance and makes business decisions. We have two major business segments, Key Community Bank and Key Corporate Bank. We also have Other Segments that consists of corporate treasury, our principal investing unit, and various exit portfolios. Total assets included under “Reconciling Items” primarily represents the unallocated portion of nonearning assets of corporate support functions. Charges related to the funding of these assets are part of net interest income and are allocated to the business segments through noninterest expense. Reconciling items also includes intercompany eliminations and certain items that are not allocated to the business segments because they do not reflect their normal operations. For more information on our business segments, see Note 25 (" Line of Business Results ") on page 183 of our 2017 Form 10-K. The development and application of the methodologies that we use to allocate items among our lines of business is a dynamic process. Accordingly, financial results may be revised periodically to reflect enhanced alignment of expense base allocations drivers, changes in the risk profile of a particular business, or changes in our organizational structure. The table on the following pages shows selected financial data for our major business segments for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 . Three months ended June 30, Key Community Bank Key Corporate Bank dollars in millions 2018 2017 2018 2017 SUMMARY OF OPERATIONS Net interest income (TE) $ 715 $ 676 $ 277 $ 312 Noninterest income 281 322 265 285 Total revenue (TE) (a) 996 998 542 597 Provision for credit losses 38 47 28 19 Depreciation and amortization expense 28 28 33 22 Other noninterest expense 611 607 293 275 Income (loss) from continuing operations before income taxes (TE) 319 316 188 281 Allocated income taxes and TE adjustments 75 118 21 57 Income (loss) from continuing operations 244 198 167 224 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) 244 198 167 224 Less: Net income (loss) attributable to noncontrolling interests — — — — Net income (loss) attributable to Key $ 244 $ 198 $ 167 $ 224 AVERAGE BALANCES (b) Loans and leases $ 47,984 $ 47,477 $ 39,710 $ 37,704 Total assets (a) 51,866 51,441 47,213 44,131 Deposits 80,930 79,601 21,057 21,145 OTHER FINANCIAL DATA Net loan charge-offs (b) $ 34 $ 47 $ 26 $ 19 Return on average allocated equity (b) 20.22 % 16.59 % 23.07 % 31.66 % Return on average allocated equity 20.22 16.59 23.07 31.66 Average full-time equivalent employees (c) 10,619 10,558 2,537 2,364 Six months ended June 30, Key Community Bank Key Corporate Bank dollars in millions 2018 2017 2018 2017 SUMMARY OF OPERATIONS Net interest income (TE) $ 1,403 $ 1,305 $ 549 $ 616 Noninterest income 551 583 552 559 Total revenue (TE) (a) 1,954 1,888 1,101 1,175 Provision for credit losses 86 94 42 36 Depreciation and amortization expense 57 56 67 42 Other noninterest expense 1,233 1,185 573 561 Income (loss) from continuing operations before income taxes (TE) 578 553 419 536 Allocated income taxes and TE adjustments 137 206 45 133 Income (loss) from continuing operations 441 347 374 403 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) 441 347 374 403 Less: Net income (loss) attributable to noncontrolling interests — — — (1 ) Net income (loss) attributable to Key $ 441 $ 347 $ 374 $ 404 AVERAGE BALANCES (b) Loans and leases $ 47,833 $ 47,282 $ 38,989 $ 37,696 Total assets (a) 51,736 51,215 46,386 44,128 Deposits 80,440 79,375 20,937 21,074 OTHER FINANCIAL DATA Net loan charge-offs (b) $ 76 $ 90 $ 38 $ 33 Return on average allocated equity (b) 18.43 % 14.70 % 26.21 % 28.27 % Return on average allocated equity 18.43 14.70 26.21 28.27 Average full-time equivalent employees (c) 10,642 10,511 2,540 2,374 (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 2018 2017 2018 2017 2018 2017 2018 2017 $ (12 ) $ (8 ) $ 980 $ 980 $ 7 $ 7 $ 987 $ 987 50 54 596 661 64 (8 ) 660 653 38 46 1,576 1,641 71 (1 ) 1,647 1,640 (1 ) — 65 66 (1 ) — 64 66 — 1 61 51 38 42 99 93 16 26 920 908 (26 ) (6 ) 894 902 23 19 530 616 60 (37 ) 590 579 (2 ) (5 ) 94 170 17 2 111 172 25 24 436 446 43 (39 ) 479 407 — — — — 3 5 3 5 25 24 436 446 46 (34 ) 482 412 — — — — — — — — $ 25 $ 24 $ 436 $ 446 $ 46 $ (34 ) $ 482 $ 412 $ 934 $ 1,288 $ 88,628 $ 86,469 $ 16 $ 33 $ 88,644 $ 86,502 36,932 36,181 136,011 131,753 367 738 136,378 132,491 1,960 2,050 103,947 102,796 56 (17 ) 104,003 102,779 1 — $ 60 $ 66 — $ — $ 60 $ 66 78.96 % 61.31 % 22.22 % 22.99 % 2.41 % (2.11 )% 12.78 % 10.74 % 78.96 61.31 22.22 22.99 2.58 (1.84 ) 12.86 10.87 195 342 13,351 13,264 5,025 5,080 18,376 18,344 Other Segments Total Segments Reconciling Items Key 2018 2017 2018 2017 2018 2017 2018 2017 $ (26 ) $ (12 ) $ 1,926 $ 1,909 $ 13 $ 7 $ 1,939 $ 1,916 101 102 1,204 1,244 57 (14 ) 1,261 1,230 75 90 3,130 3,153 70 (7 ) 3,200 3,146 (2 ) — 126 130 (1 ) (1 ) 125 129 1 1 125 99 78 87 203 186 39 52 1,845 1,798 (49 ) 24 1,796 1,822 37 37 1,034 1,126 42 (117 ) 1,076 1,009 (7 ) (10 ) 175 329 6 (52 ) 181 277 44 47 859 797 36 (65 ) 895 732 — — — — 5 5 5 5 44 47 859 797 41 (60 ) 900 737 — 2 — 1 — — — 1 $ 44 $ 45 $ 859 $ 796 $ 41 $ (60 ) $ 900 $ 736 $ 963 $ 1,308 $ 87,785 $ 86,286 $ 5 $ 32 $ 87,790 $ 86,318 37,130 36,403 135,252 131,746 399 869 135,651 132,615 1,840 2,040 103,217 102,489 66 (59 ) 103,283 102,430 1 $ 1 $ 114 $ 124 — — $ 114 $ 124 66.22 % 56.36 % 22.10 % 20.57 % 1.02 % (1.77 )% 12.06 % 9.70 % 66.22 56.36 22.10 20.57 1.16 (1.64 ) 12.13 9.77 259 343 13,441 13,228 5,017 5,137 18,458 18,365

Revenue from Contracts with Cus

Revenue from Contracts with Customers	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	19. Revenue from Contracts with Customers The following table represents a disaggregation of revenue from contracts with customers, by line of business, for the three- and six- month periods ended June 30, 2018 : Three months ended June 30, 2018 dollars in millions Key Community Bank Key Corporate Bank Total Contract Revenue NONINTEREST INCOME Trust and investment services income $ 91 $ 18 $ 109 Investment banking and debt placement fees 1 67 68 Services charges on deposit accounts 78 13 91 Cards and payments income 40 29 69 Other noninterest income 5 — 5 Total revenue from contracts with customers $ 215 $ 127 $ 342 Other noninterest income (a) $ 204 Noninterest income from other segments (b) 50 Reconciling items (c) 64 Total noninterest income $ 660 (a) Noninterest income considered earned outside the scope of contracts with customers. (b) Other Segments consist of corporate treasury, our principle investing unit, and various exit portfolios. (c) Reconciling items consists primarily of the gain on the sale of, and contract revenue recognized prior to the sale of, Key Insurance and Benefits Services for the second quarter of 2018, intercompany eliminations, and items not allocated to the business segments because they do not reflect their normal operations. Refer to the Line of Business Results footnote for more information. Six months ended June 30, 2018 dollars in millions Key Community Bank Key Corporate Bank Total Contract Revenue NONINTEREST INCOME Trust and investment services income $ 179 $ 33 $ 212 Investment banking and debt placement fees 1 114 115 Services charges on deposit accounts 153 26 179 Cards and payments income 75 55 130 Other noninterest income 10 — 10 Total revenue from contracts with customers $ 418 $ 228 $ 646 Other noninterest income (a) $ 457 Noninterest income from other segments (b) 101 Reconciling items (c) 57 Total noninterest income $ 1,261 (a) Noninterest income considered earned outside the scope of contracts with customers. (b) Other Segments consist of corporate treasury, our principle investing unit, and various exit portfolios. (c) Reconciling items consists primarily of the gain on the sale of, and contract revenue recognized prior to the sale of, Key Insurance and Benefits Services for the second quarter of 2018, intercompany eliminations, and items not allocated to the business segments because they do not reflect their normal operations. Refer to the Line of Business Results footnote for more information. We have no material contract assets or contract liabilities for the three- and six- month periods ended June 30, 2018

Basis of Presentation and Acc30

Basis of Presentation and Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation	The consolidated financial statements include the accounts of KeyCorp and its subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. Some previously reported amounts have been reclassified to conform to current reporting practices. The consolidated financial statements include any voting rights entities in which we have a controlling financial interest. In accordance with the applicable accounting guidance for consolidations, we consolidate a VIE if we have: (i) a variable interest in the entity; (ii) the power to direct activities of the VIE that most significantly affect the entity’s economic performance; and (iii) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE (i.e., we are considered to be the primary beneficiary). Variable interests can include equity interests, subordinated debt, derivative contracts, leases, service agreements, guarantees, standby letters of credit, loan commitments, and other contracts, agreements, and financial instruments. See Note 9 (“ Variable Interest Entities ”) for information on our involvement with VIEs. We use the equity method to account for unconsolidated investments in voting rights entities or VIEs if we have significant influence over the entity’s operating and financing decisions (usually defined as a voting or economic interest of 20% to 50% , but not controlling). Unconsolidated investments in voting rights entities or VIEs in which we have a voting or economic interest of less than 20% are carried at the cost measurement alternative or at fair value. Investments held by our registered broker-dealer and investment company subsidiaries (principal investing entities and Real Estate Capital line of business) are carried at fair value. We believe that the unaudited consolidated interim financial statements reflect all adjustments of a normal recurring nature and disclosures that are necessary for a fair presentation of the results for the interim periods presented. The results of operations for the interim period are not necessarily indicative of the results of operations to be expected for the full year. The interim financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in our 2017
Subsequent Events	In preparing these financial statements, subsequent events were evaluated through the time the financial statements were issued. Financial statements are considered issued when they are widely distributed to all shareholders and other financial statement users or filed with the SEC.
Accounting Guidance Adopted and Pending Adoption	Standard Date of Adoption Description Effect on Financial Statements or Other Significant Matters ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ASU 2015-14, Deferral of Effective Date ASU 2016-08, Principal versus Agent Considerations ASU 2016-10, Identifying Performance Obligations and Licensing ASU 2016-11, Rescission of SEC Guidance because of Accounting Standard Updates 2014-09 and 2014-16 pursuant to Staff Announcements at the March 3, 2016 EITF Meeting ASU 2016-12, Narrow-scope Improvements and Practical Expedients ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers January 1, 2018 These ASUs supersede the revenue recognition guidance in ASC 605, Revenue Recognition, and most industry-specific guidance. The core principle of these ASUs is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. These ASUs can be implemented using a retrospective method, or a cumulative-effect approach to new contracts and existing contracts with performance obligations as of the effective date. On January 1, 2018, we adopted ASC 606, Revenue from Contracts with Customers (ASC 606), using the modified retrospective method for those contracts which were not completed as of that date. Results for reporting periods beginning January 1, 2018, are presented under ASC 606. As allowed under the new guidance, the comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. As a result of adopting ASC 606, we changed the timing of recognition for revenues related to insurance commissions, securities underwriting, and deposit account maintenance fees, however, those changes did not have a material impact on our consolidated financial statements, results of operations, equity, or cash flows as of the adoption date or for the six months ended June 30, 2018. The presentation of underwriting costs and reimbursed out-of-pocket expenses related to underwriting and M&A advisory services was changed from net to gross within the income statement as Key acts as the principal in the transactions. Securities underwriting revenue is recorded within "investment banking and debt placement fees" and underwriting costs and reimbursed out-of-pocket expenses within "other expense" on the income statement. Additionally, because Key acts as an agent, certain credit and debit card reward costs and certain card network costs were changed from a gross presentation to net within "cards and payment income" on the income statement. Credit and debit card reward costs and card network costs were recorded as "other expense" on the income statement in prior periods. These changes in presentation did not have a material impact on our consolidated financial statements for the six months ended June 30, 2018. ASC 606 requires quantitative disclosure of the allocation of the transaction price to the remaining performance obligations when those amounts are expected to be recognized as revenue. However, the standard provides exemptions from this disclosure for (i) contracts with an original expected length of one year or less and (ii) contracts for which we recognize revenue at the amount to which we have the right to invoice for services provided. Most of our revenue subject to ASC 606 fits into one of these exemptions, or is immaterial. We elected to use the optional exemption to not disclose the aggregate amount of the transaction price to remaining performance obligations. ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities January 1, 2018 The ASU amends ASC Topic 815, Derivatives and Hedging , to simplify the requirements for hedge accounting and facilitate financial reporting that more closely aligns with an entity’s risk management activities. Key amendments include: eliminating the requirement to separately measure and report hedge ineffectiveness, requiring changes in the value of the hedging instrument to be presented in the same income statement line as the earnings effect of the hedged item, and the ability to measure the hedged item based on the benchmark interest rate component of the total contractual coupon for fair value hedges. Additional disclosures are also required for reporting periods subsequent to the date of adoption. The guidance should be implemented on a modified retrospective basis to existing hedge relationships as of the adoption date. On January 1, 2018, we adopted this ASU using a modified retrospective basis. Accordingly, our financial statements for the quarter ended June 30, 2018, include an immaterial cumulative-effect adjustment to decrease opening retained earnings to reflect the application of the new guidance as of January 1, 2018. The primary impact to Key at adoption was the election to measure the change in fair value of hedged items in fair value hedges on the basis of the benchmark interest rate component of contractual coupon cash flows. This change has resulted in a reduction of hedge ineffectiveness for impacted fair value hedges. Instruments designated as hedges are recorded at fair value and included in “accrued income and other assets” or “accrued expense and other liabilities” on the balance sheet. Under the revised guidance, the change in the fair value of an instrument designated as a fair value hedge is recorded in earnings at the same time and in the same income statement line as the offsetting change in the fair value of the hedged item. For cash flow hedges, the change in the fair value of an instrument designated as a cash flow hedge is initially recorded in AOCI on the balance sheet. This amount is subsequently reclassified into income when the hedged transaction affects earnings and is presented in the same income statement line item as the earnings effect of the hedged item. Standard Date of Adoption Description Effect on Financial Statements or Other Significant Matters ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities January 1, 2018 The ASU amends ASC Topic 825, Financial Instruments-Overall, and requires equity investments, except those accounted for under the equity method of accounting or consolidated, to be measured at fair value with changes recognized in net income. If there is no readily determinable fair value, the guidance allows entities the ability to measure investments at cost less impairment, whereby impairment is based on a qualitative assessment. The guidance eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost and changes the presentation of financial assets and financial liabilities on the balance sheet or in the footnotes. If an entity has elected the fair value option to measure liabilities, the new accounting guidance requires the portion of the change in the fair value of a liability resulting from credit risk to be presented in OCI. With the exception of disclosure requirements that will be adopted prospectively, the ASU must be adopted on a modified retrospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments January 1, 2018 The ASU amends ASC Topic 230, Statement of Cash Flows , and clarifies how cash receipts and cash payments in certain transactions should be presented and classified in the statement of cash flows. These specific transactions include, but are not limited to, debt prepayment or extinguishment costs, contingent considerations made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, and distributions from equity method investees. This guidance also clarifies that in instances of cash flows with multiple aspects that cannot be separately identified, classification should be based on the activity that is likely to be the predominant source of or use of cash flow. The guidance should be implemented using a retrospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-01, Clarifying the Definition of a Business January 1, 2018 The ASU amends Topic 805, Business Combinations, and clarifies the definition of a business and removes the requirement for a market participant to consider whether it could replace missing elements in an integrated set of assets and activities. The guidance states that if substantially all of the fair value of the assets acquired or disposed of is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The guidance should be implemented using a prospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-05, Other Income- Gains and Losses from the Derecognition of Nonfinancial Assets January 1, 2018 The ASU amends ASC Topic 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets to clarify the scope of the Topic by clarifying the definition of the term "in substance nonfinancial asset" and also adding guidance for partial sales of nonfinancial assets. Under the new guidance, an entity will derecognize a nonfinancial asset when it does not have or ceases to have a controlling interest in the legal entity that holds the asset and when control of the asset has transferred in accordance with ASC 606. The ASU can be adopted on a retrospective or modified retrospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost January 1, 2018 The ASU amends ASC Topic 715, Compensation - Retirement Benefits , and requires service costs to be included in the same line item as certain other compensation costs related to services rendered by employees. We record compensation costs under personnel expense on the income statement. Other elements of net benefit cost should be presented separately. The guidance should be implemented on a retrospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-09, Scope of Modification Accounting January 1, 2018 The ASU amends ASC Topic 718, Compensation - Stock Compensation , and clarifies when changes to terms and conditions for share-based payment awards should be accounted for as modifications. Under the new guidance, entities should apply the modification guidance unless the fair value of the modified award is the same as the fair value of the original award immediately before modification, the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before modification, and the classification of the modified award (as equity or liability instrument) is the same as the classification of the original award immediately before modification. The guidance should be applied on a prospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations.

Basis of Presentation and Acc31

Basis of Presentation and Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	Accounting Guidance Adopted in 2018 Standard Date of Adoption Description Effect on Financial Statements or Other Significant Matters ASU 2014-09, Revenue from Contracts with Customers (Topic 606) ASU 2015-14, Deferral of Effective Date ASU 2016-08, Principal versus Agent Considerations ASU 2016-10, Identifying Performance Obligations and Licensing ASU 2016-11, Rescission of SEC Guidance because of Accounting Standard Updates 2014-09 and 2014-16 pursuant to Staff Announcements at the March 3, 2016 EITF Meeting ASU 2016-12, Narrow-scope Improvements and Practical Expedients ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers January 1, 2018 These ASUs supersede the revenue recognition guidance in ASC 605, Revenue Recognition, and most industry-specific guidance. The core principle of these ASUs is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. These ASUs can be implemented using a retrospective method, or a cumulative-effect approach to new contracts and existing contracts with performance obligations as of the effective date. On January 1, 2018, we adopted ASC 606, Revenue from Contracts with Customers (ASC 606), using the modified retrospective method for those contracts which were not completed as of that date. Results for reporting periods beginning January 1, 2018, are presented under ASC 606. As allowed under the new guidance, the comparative information has not been restated and continues to be reported under the accounting standards in effect for those periods. As a result of adopting ASC 606, we changed the timing of recognition for revenues related to insurance commissions, securities underwriting, and deposit account maintenance fees, however, those changes did not have a material impact on our consolidated financial statements, results of operations, equity, or cash flows as of the adoption date or for the six months ended June 30, 2018. The presentation of underwriting costs and reimbursed out-of-pocket expenses related to underwriting and M&A advisory services was changed from net to gross within the income statement as Key acts as the principal in the transactions. Securities underwriting revenue is recorded within "investment banking and debt placement fees" and underwriting costs and reimbursed out-of-pocket expenses within "other expense" on the income statement. Additionally, because Key acts as an agent, certain credit and debit card reward costs and certain card network costs were changed from a gross presentation to net within "cards and payment income" on the income statement. Credit and debit card reward costs and card network costs were recorded as "other expense" on the income statement in prior periods. These changes in presentation did not have a material impact on our consolidated financial statements for the six months ended June 30, 2018. ASC 606 requires quantitative disclosure of the allocation of the transaction price to the remaining performance obligations when those amounts are expected to be recognized as revenue. However, the standard provides exemptions from this disclosure for (i) contracts with an original expected length of one year or less and (ii) contracts for which we recognize revenue at the amount to which we have the right to invoice for services provided. Most of our revenue subject to ASC 606 fits into one of these exemptions, or is immaterial. We elected to use the optional exemption to not disclose the aggregate amount of the transaction price to remaining performance obligations. ASU 2017-12, Targeted Improvements to Accounting for Hedging Activities January 1, 2018 The ASU amends ASC Topic 815, Derivatives and Hedging , to simplify the requirements for hedge accounting and facilitate financial reporting that more closely aligns with an entity’s risk management activities. Key amendments include: eliminating the requirement to separately measure and report hedge ineffectiveness, requiring changes in the value of the hedging instrument to be presented in the same income statement line as the earnings effect of the hedged item, and the ability to measure the hedged item based on the benchmark interest rate component of the total contractual coupon for fair value hedges. Additional disclosures are also required for reporting periods subsequent to the date of adoption. The guidance should be implemented on a modified retrospective basis to existing hedge relationships as of the adoption date. On January 1, 2018, we adopted this ASU using a modified retrospective basis. Accordingly, our financial statements for the quarter ended June 30, 2018, include an immaterial cumulative-effect adjustment to decrease opening retained earnings to reflect the application of the new guidance as of January 1, 2018. The primary impact to Key at adoption was the election to measure the change in fair value of hedged items in fair value hedges on the basis of the benchmark interest rate component of contractual coupon cash flows. This change has resulted in a reduction of hedge ineffectiveness for impacted fair value hedges. Instruments designated as hedges are recorded at fair value and included in “accrued income and other assets” or “accrued expense and other liabilities” on the balance sheet. Under the revised guidance, the change in the fair value of an instrument designated as a fair value hedge is recorded in earnings at the same time and in the same income statement line as the offsetting change in the fair value of the hedged item. For cash flow hedges, the change in the fair value of an instrument designated as a cash flow hedge is initially recorded in AOCI on the balance sheet. This amount is subsequently reclassified into income when the hedged transaction affects earnings and is presented in the same income statement line item as the earnings effect of the hedged item. Standard Date of Adoption Description Effect on Financial Statements or Other Significant Matters ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities January 1, 2018 The ASU amends ASC Topic 825, Financial Instruments-Overall, and requires equity investments, except those accounted for under the equity method of accounting or consolidated, to be measured at fair value with changes recognized in net income. If there is no readily determinable fair value, the guidance allows entities the ability to measure investments at cost less impairment, whereby impairment is based on a qualitative assessment. The guidance eliminates the requirement to disclose the methods and significant assumptions used to estimate the fair value of financial instruments measured at amortized cost and changes the presentation of financial assets and financial liabilities on the balance sheet or in the footnotes. If an entity has elected the fair value option to measure liabilities, the new accounting guidance requires the portion of the change in the fair value of a liability resulting from credit risk to be presented in OCI. With the exception of disclosure requirements that will be adopted prospectively, the ASU must be adopted on a modified retrospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments January 1, 2018 The ASU amends ASC Topic 230, Statement of Cash Flows , and clarifies how cash receipts and cash payments in certain transactions should be presented and classified in the statement of cash flows. These specific transactions include, but are not limited to, debt prepayment or extinguishment costs, contingent considerations made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, and distributions from equity method investees. This guidance also clarifies that in instances of cash flows with multiple aspects that cannot be separately identified, classification should be based on the activity that is likely to be the predominant source of or use of cash flow. The guidance should be implemented using a retrospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-01, Clarifying the Definition of a Business January 1, 2018 The ASU amends Topic 805, Business Combinations, and clarifies the definition of a business and removes the requirement for a market participant to consider whether it could replace missing elements in an integrated set of assets and activities. The guidance states that if substantially all of the fair value of the assets acquired or disposed of is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. The guidance should be implemented using a prospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-05, Other Income- Gains and Losses from the Derecognition of Nonfinancial Assets January 1, 2018 The ASU amends ASC Topic 610-20, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets to clarify the scope of the Topic by clarifying the definition of the term "in substance nonfinancial asset" and also adding guidance for partial sales of nonfinancial assets. Under the new guidance, an entity will derecognize a nonfinancial asset when it does not have or ceases to have a controlling interest in the legal entity that holds the asset and when control of the asset has transferred in accordance with ASC 606. The ASU can be adopted on a retrospective or modified retrospective approach. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost January 1, 2018 The ASU amends ASC Topic 715, Compensation - Retirement Benefits , and requires service costs to be included in the same line item as certain other compensation costs related to services rendered by employees. We record compensation costs under personnel expense on the income statement. Other elements of net benefit cost should be presented separately. The guidance should be implemented on a retrospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations. ASU 2017-09, Scope of Modification Accounting January 1, 2018 The ASU amends ASC Topic 718, Compensation - Stock Compensation , and clarifies when changes to terms and conditions for share-based payment awards should be accounted for as modifications. Under the new guidance, entities should apply the modification guidance unless the fair value of the modified award is the same as the fair value of the original award immediately before modification, the vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before modification, and the classification of the modified award (as equity or liability instrument) is the same as the classification of the original award immediately before modification. The guidance should be applied on a prospective basis. The adoption of this guidance did not have a material effect on our financial condition or results of operations.

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Basic and Diluted Earnings Per Common Share	Our basic and diluted earnings per Common Share are calculated as follows: Three months ended June 30, Six months ended June 30, dollars in millions, except per share amounts 2018 2017 2018 2017 EARNINGS Income (loss) from continuing operations $ 479 $ 407 $ 895 $ 732 Less: Net income (loss) attributable to noncontrolling interests — — — 1 Income (loss) from continuing operations attributable to Key 479 407 895 731 Less: Dividends on Preferred Stock 15 14 29 42 Income (loss) from continuing operations attributable to Key common shareholders 464 393 866 689 Income (loss) from discontinued operations, net of taxes 3 5 5 5 Net income (loss) attributable to Key common shareholders $ 467 $ 398 $ 871 $ 694 WEIGHTED-AVERAGE COMMON SHARES Weighted-average common shares outstanding (000) 1,052,652 1,076,203 1,054,378 1,083,486 Effect of Common Share options and other stock awards 13,141 16,836 14,561 15,808 Weighted-average Common Shares and potential Common Shares outstanding (000) (a) 1,065,793 1,093,039 1,068,939 1,099,294 EARNINGS PER COMMON SHARE Income (loss) from continuing operations attributable to Key common shareholders $ .44 $ .36 $ .82 $ .64 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) attributable to Key common shareholders (b) .44 .37 .82 .64 Income (loss) from continuing operations attributable to Key common shareholders — assuming dilution $ .44 $ .36 $ .81 $ .63 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) attributable to Key common shareholders — assuming dilution (b) .44 .36 .81 .63 (a)

Loan Portfolio (Tables)

Loan Portfolio (Tables)	6 Months Ended
	Jun. 30, 2018
Loans Receivables [Abstract]
Loans by Category	in millions June 30, 2018 December 31, 2017 Commercial and industrial (a) $ 44,569 $ 41,859 Commercial real estate: Commercial mortgage 14,162 14,088 Construction 1,736 1,960 Total commercial real estate loans 15,898 16,048 Commercial lease financing (b) 4,509 4,826 Total commercial loans 64,976 62,733 Residential — prime loans: Real estate — residential mortgage 5,452 5,483 Home equity loans 11,519 12,028 Total residential — prime loans 16,971 17,511 Consumer direct loans 1,785 1,794 Credit cards 1,094 1,106 Consumer indirect loans 3,396 3,261 Total consumer loans 23,246 23,672 Total loans (c) $ 88,222 $ 86,405 (a) Loan balances include $128 million and $119 million of commercial credit card balances at June 30, 2018 , and December 31, 2017 , respectively. (b) Commercial lease financing includes receivables held as collateral for a secured borrowing of $16 million and $24 million at June 30, 2018 , and December 31, 2017 , respectively. Principal reductions are based on the cash payments received from these related receivables. Additional information pertaining to this secured borrowing is included in Note 20 (“ Long-Term Debt ”) beginning on page 174 of our 2017 Form 10-K. (c) Total loans exclude loans of $1.2 billion at June 30, 2018 , and $1.3 billion at December 31, 2017

Asset Quality (Tables)

Asset Quality (Tables)	6 Months Ended
	Jun. 30, 2018
Receivables [Abstract]
Financing Receivable Credit Quality Indicators	Commercial Credit Exposure — Excluding PCI Credit Risk Profile by Creditworthiness Category (a), (b) Commercial and industrial RE — Commercial RE — Construction Commercial lease Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, RATING 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 Pass $ 42,517 $ 39,833 $ 13,368 $ 13,328 $ 1,682 $ 1,894 $ 4,420 $ 4,730 $ 61,987 $ 59,785 Criticized (Accruing) 1,817 1,790 540 482 49 38 68 90 2,474 2,400 Criticized (Nonaccruing) 178 153 42 30 2 2 21 6 243 191 Total $ 44,512 $ 41,776 $ 13,950 $ 13,840 $ 1,733 $ 1,934 $ 4,509 $ 4,826 $ 64,704 $ 62,376 (a) Credit quality indicators are updated on an ongoing basis and reflect credit quality information as of the dates indicated. (b) The term criticized refers to those loans that are internally classified by Key as special mention or worse, which are asset quality categories defined by regulatory authorities. These assets have an elevated level of risk and may have a high probability of default or total loss. Pass rated refers to all loans not classified as criticized. Consumer Credit Exposure — Excluding PCI Non-PCI Loans by Refreshed FICO Score (a) Residential — Prime Consumer direct loans Credit cards Consumer indirect loans Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, FICO SCORE 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 750 and above $ 10,004 $ 10,226 $ 517 $ 519 $ 482 $ 477 $ 1,493 $ 1,472 $ 12,496 $ 12,694 660 to 749 4,871 5,181 673 690 502 508 1,181 1,184 7,227 7,563 Less than 660 1,564 1,519 211 225 110 121 503 529 2,388 2,394 No Score 179 208 380 356 — — 219 76 778 640 Total $ 16,618 $ 17,134 $ 1,781 $ 1,790 $ 1,094 $ 1,106 $ 3,396 $ 3,261 $ 22,889 $ 23,291 (a) Borrower FICO scores provide information about the credit quality of our consumer loan portfolio as they provide an indication as to the likelihood that a debtor will repay its debts. The scores are obtained from a nationally recognized consumer rating agency and are presented in the above table at the dates indicated. Commercial Credit Exposure — PCI Credit Risk Profile by Creditworthiness Category (a), (b) Commercial and Industrial RE — Commercial RE — Construction Commercial Lease Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, RATING 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 Pass $ 25 $ 41 $ 140 $ 153 $ 3 $ 26 — — $ 168 $ 220 Criticized 32 42 72 95 — — — — 104 137 Total $ 57 $ 83 $ 212 $ 248 $ 3 $ 26 — — $ 272 $ 357 (a) Credit quality indicators are updated on an ongoing basis and reflect credit quality information as of the dates indicated. (b) The term “criticized” refers to those loans that are internally classified by Key as special mention or worse, which are asset quality categories defined by regulatory authorities. These assets have an elevated level of risk and may have a high probability of default or total loss. Pass rated refers to all loans not classified as criticized. Consumer Credit Exposure — PCI PCI Loans by Refreshed FICO Score (a) Residential — Prime Consumer direct loans Credit cards Consumer indirect loans Total in millions June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, June 30, December 31, FICO SCORE 2018 2017 2018 2017 2018 2017 2018 2017 2018 2017 750 and above $ 142 $ 149 $ 1 — — — — — $ 143 $ 149 660 to 749 102 117 1 $ 2 — — — — 103 119 Less than 660 107 105 2 2 — — — — 109 107 No Score 2 6 — — — — — — 2 6 Total $ 353 $ 377 $ 4 $ 4 — — — — $ 357 $ 381 (a) Borrower FICO scores provide information about the credit quality of our consumer loan portfolio as they provide an indication as to the likelihood that a debtor will repay its debts. The scores are obtained from a nationally recognized consumer rating agency and are presented in the above table at the dates indicated.
Past Due Loans Including Current Loans	The following aging analysis of past due and current loans as of June 30, 2018 , and December 31, 2017 , provides further information regarding Key’s credit exposure. Aging Analysis of Loan Portfolio (a) June 30, 2018 Current 30-59 Days Past Due (b) 60-89 Days Past Due (b) 90 and Greater Days Past Due (b) Non-performing Loans Total Past Due and Non-performing Loans Purchased Credit Impaired Total Loans (c), (d) in millions LOAN TYPE Commercial and industrial $ 44,137 $ 129 $ 40 $ 28 $ 178 $ 375 $ 57 $ 44,569 Commercial real estate: Commercial mortgage 13,740 38 100 30 42 210 212 14,162 Construction 1,719 2 1 9 2 14 3 1,736 Total commercial real estate loans 15,459 40 101 39 44 224 215 15,898 Commercial lease financing 4,467 15 2 4 21 42 — 4,509 Total commercial loans $ 64,063 $ 184 $ 143 $ 71 $ 243 $ 641 $ 272 $ 64,976 Real estate — residential mortgage $ 5,039 $ 11 $ 8 $ 6 $ 55 $ 80 $ 333 $ 5,452 Home equity loans 11,235 25 9 8 222 264 20 11,519 Consumer direct loans 1,759 8 4 6 4 22 4 1,785 Credit cards 1,073 5 4 10 2 21 — 1,094 Consumer indirect loans 3,347 23 5 2 19 49 — 3,396 Total consumer loans $ 22,453 $ 72 $ 30 $ 32 $ 302 $ 436 $ 357 $ 23,246 Total loans $ 86,516 $ 256 $ 173 $ 103 $ 545 $ 1,077 $ 629 $ 88,222 (a) Amounts in table represent recorded investment and exclude loans held for sale. Recorded investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. (b) Past due loan amounts exclude PCI, even if contractually past due (or if we do not expect to collect principal or interest in full based on the original contractual terms), as we are currently accreting income over the remaining term of the loans. (c) Net of unearned income, net deferred loan fees and costs, and unamortized discounts and premiums. (d) Future accretable yield related to PCI loans is not included in the analysis of the loan portfolio. December 31, 2017 Current 30-59 Days Past Due (b) 60-89 Days Past Due (b) 90 and Greater Days Past Due (b) Non-performing Loans Total Past Due and Non-performing Loans Purchased Credit Impaired Total Loans (c), (d) in millions LOAN TYPE Commercial and industrial $ 41,444 $ 111 $ 34 $ 34 $ 153 $ 332 83 $ 41,859 Commercial real estate: Commercial mortgage 13,750 26 13 21 30 90 248 14,088 Construction 1,919 4 9 — 2 15 26 1,960 Total commercial real estate loans 15,669 30 22 21 32 105 274 16,048 Commercial lease financing 4,791 23 4 2 6 35 — 4,826 Total commercial loans $ 61,904 $ 164 $ 60 $ 57 $ 191 $ 472 357 $ 62,733 Real estate — residential mortgage $ 5,043 $ 16 $ 7 $ 4 $ 58 $ 85 $ 355 $ 5,483 Home equity loans 11,721 32 15 9 229 285 22 12,028 Consumer direct loans 1,768 9 4 5 4 22 4 1,794 Credit cards 1,081 7 5 11 2 25 — 1,106 Consumer indirect loans 3,199 33 7 3 19 62 — 3,261 Total consumer loans $ 22,812 $ 97 $ 38 $ 32 $ 312 $ 479 $ 381 $ 23,672 Total loans $ 84,716 $ 261 $ 98 $ 89 $ 503 $ 951 $ 738 $ 86,405 (a) Amounts in table represent recorded investment and exclude loans held for sale. Recorded investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. (b) Past due loan amounts exclude PCI, even if contractually past due (or if we do not expect to collect principal or interest in full based on the original contractual terms), as we are currently accreting income over the remaining term of the loans. (c) Net of unearned income, net deferred loan fees and costs, and unamortized discounts and premiums. (d) Future accretable yield related to purchased credit impaired loans is not included in the analysis of the loan portfolio.
Breakdown of Individually Impaired Loans	The following tables set forth a further breakdown of individually impaired loans as of June 30, 2018 , and December 31, 2017 : June 30, 2018 December 31, 2017 Recorded Investment (a) Unpaid Principal Balance (b) Specific Allowance Recorded Investment (a) Unpaid Principal Balance (b) Specific Allowance in millions With no related allowance recorded: Commercial and industrial $ 123 $ 154 — $ 126 $ 153 — Commercial real estate: Commercial mortgage 20 25 — 12 18 — Total commercial real estate loans 20 25 — 12 18 — Total commercial loans 143 179 — 138 171 — Real estate — residential mortgage 16 24 — 17 17 — Home equity loans 51 59 — 56 56 — Consumer indirect loans 2 4 — 2 2 — Total consumer loans 69 87 — 75 75 — Total loans with no related allowance recorded 212 266 — 213 246 — With an allowance recorded: Commercial and industrial 64 94 $ 7 10 28 $ 6 Total commercial loans 64 94 7 10 28 6 Real estate — residential mortgage 32 52 4 32 32 5 Home equity loans 74 80 10 61 61 9 Consumer direct loans 4 4 — 4 4 — Credit cards 3 3 — 2 2 — Consumer indirect loans 33 33 3 32 32 3 Total consumer loans 146 172 17 131 131 17 Total loans with an allowance recorded 210 266 24 141 159 23 Total $ 422 $ 532 $ 24 $ 354 $ 405 $ 23 (a) The Recorded Investment represents the face amount of the loan increased or decreased by applicable accrued interest, net deferred loan fees and costs, and unamortized premium or discount, and reflects direct charge-offs. This amount is a component of total loans on our Consolidated Balance Sheet. (b) The Unpaid Principal Balance represents the customer’s legal obligation to us. The following table sets forth a further breakdown of the average individually impaired loans reported by Key: Average Recorded Investment (a) Three Months Ended June 30, Six Months Ended June 30, in millions 2018 2017 2018 2017 Commercial and industrial $ 178 $ 201 $ 161 $ 225 Commercial real estate: Commercial mortgage 16 15 16 10 Construction — — — — Total commercial real estate loans 16 15 16 10 Total commercial loans 194 216 177 235 Real estate — residential mortgage 49 50 49 50 Home equity loans 124 122 121 122 Consumer direct loans 4 3 4 3 Credit cards 3 3 3 3 Consumer indirect loans 35 34 34 32 Total consumer loans 215 212 211 210 Total $ 409 $ 428 $ 388 $ 445 (a)
Post-Modification Outstanding Recorded Investment by Concession Type for Our Commercial Accruing and Nonaccruing TDRs	The following table shows the post-modification outstanding recorded investment by concession type for our commercial and consumer accruing and nonaccruing TDRs that occurred during the periods indicated: Three Months Ended June 30, Six Months Ended June 30, in millions 2018 2017 2018 2017 Commercial loans: Forgiveness of principal $ 5 — $ 5 — Extension of Maturity Date 14 $ 15 15 $ 17 Payment or Covenant Modification/Deferment 20 11 20 35 Bankruptcy Plan Modification 7 29 7 29 Total $ 46 $ 55 $ 47 $ 81 Consumer loans: Interest rate reduction $ 10 $ 4 $ 18 $ 7 Forgiveness of principal — — — — Other 9 4 21 17 Total $ 19 $ 8 $ 39 $ 24 Total commercial and consumer TDRs $ 65 $ 63 $ 86 $ 105
Summary Of Post-Modification Outstanding Recorded Investment, Accruing And Nonaccruing TDRs	The following table summarizes the change in the post-modification outstanding recorded investment of our accruing and nonaccruing TDRs during the periods indicated: Three Months Ended June 30, Six Months Ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of the period $ 317 $ 302 $ 317 $ 280 Additions 54 67 75 114 Payments (22 ) (33 ) (41 ) (47 ) Charge-offs (2 ) (3 ) (4 ) (14 ) Balance at end of period (a) $ 347 $ 333 $ 347 $ 333
Breakdown of Nonperforming TDRs by Loans Category	A further breakdown of TDRs included in nonperforming loans by loan category for the periods indicated are as follows: June 30, 2018 December 31, 2017 Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment Number of Loans Pre-modification Outstanding Recorded Investment Post-modification Outstanding Recorded Investment dollars in millions LOAN TYPE Nonperforming: Commercial and industrial 44 $ 106 $ 86 20 $ 109 $ 86 Commercial real estate: Commercial mortgage 6 13 9 8 16 12 Total commercial real estate loans 6 13 9 8 16 12 Total commercial loans 50 119 95 28 125 98 Real estate — residential mortgage 264 18 17 308 18 18 Home equity loans 1,072 60 57 1,025 64 57 Consumer direct loans 119 2 2 114 2 2 Credit cards 252 1 1 322 2 1 Consumer indirect loans 878 16 12 825 16 13 Total consumer loans 2,585 97 89 2,594 102 91 Total nonperforming TDRs 2,635 216 184 2,622 227 189 Prior-year accruing: (a) Commercial and industrial 18 54 37 4 30 13 Commercial real estate Commercial mortgage — — — — — — Total commercial real estate loans — — — — — — Total commercial loans 18 54 37 4 30 13 Real estate — residential mortgage 517 37 32 484 31 31 Home equity loans 1,440 85 68 1,276 75 59 Consumer direct loans 82 4 3 48 3 2 Credit cards 513 3 1 430 1 1 Consumer indirect loans 501 35 22 320 31 22 Total consumer loans 3,053 164 126 2,558 141 115 Total prior-year accruing TDRs 3,071 218 163 2,562 171 128 Total TDRs 5,706 $ 434 $ 347 5,184 $ 398 $ 317 (a) All TDRs that were restructured prior to January 1, 2018 , and January 1, 2017 , and are fully accruing.
Changes in Allowance for Loan and Lease Losses by Loan Category	The changes in the ALLL by loan category for the periods indicated are as follows: Three months ended June 30, 2018 : in millions March 31, 2018 Provision Charge-offs Recoveries June 30, 2018 Commercial and Industrial $ 533 $ 41 $ (39 ) $ 7 $ 542 Commercial real estate: Real estate — commercial mortgage 136 4 (2 ) 1 139 Real estate — construction 33 (5 ) — — 28 Total commercial real estate loans 169 (1 ) (2 ) 1 167 Commercial lease financing 40 4 (4 ) — 40 Total commercial loans 742 44 (45 ) 8 749 Real estate — residential mortgage 9 1 — — 10 Home equity loans 38 2 (6 ) 3 37 Consumer direct loans 27 6 (9 ) 2 26 Credit cards 45 11 (12 ) 2 46 Consumer indirect loans 20 2 (7 ) 4 19 Total consumer loans 139 22 (34 ) 11 138 Total ALLL — continuing operations 881 66 (a) (79 ) 19 887 Discontinued operations 16 — (3 ) 1 14 Total ALLL — including discontinued operations $ 897 $ 66 $ (82 ) $ 20 $ 901 (a) Excludes a credit for losses on lending-related commitments of $2 million . Three months ended June 30, 2017 : in millions March 31, 2017 Provision Charge-offs Recoveries June 30, 2017 Commercial and Industrial $ 512 $ 54 $ (40 ) $ 2 $ 528 Commercial real estate: Real estate — commercial mortgage 146 1 (3 ) — 144 Real estate — construction 29 (1 ) — — 28 Total commercial real estate loans 175 — (3 ) — 172 Commercial lease financing 40 1 (1 ) — 40 Total commercial loans 727 55 (44 ) 2 740 Real estate — residential mortgage 18 (6 ) (4 ) 1 9 Home equity loans 53 (7 ) (9 ) 5 42 Consumer direct loans 24 7 (8 ) 2 25 Credit cards 38 16 (12 ) 2 44 Consumer indirect loans 10 1 (5 ) 4 10 Total consumer loans 143 11 (38 ) 14 130 Total ALLL — continuing operations 870 66 (82 ) 16 870 Discontinued operations 23 — (4 ) 2 21 Total ALLL — including discontinued operations $ 893 $ 66 $ (86 ) $ 18 $ 891 Six months ended June 30, 2018 : in millions December 31, 2017 Provision Charge-offs Recoveries June 30, 2018 Commercial and Industrial 529 $ 76 $ (76 ) $ 13 $ 542 Commercial real estate: Real estate — commercial mortgage 133 8 (3 ) 1 139 Real estate — construction 30 (3 ) — 1 28 Total commercial real estate loans 163 5 (3 ) 2 167 Commercial lease financing 43 1 (5 ) 1 40 Total commercial loans 735 82 (84 ) 16 749 Real estate — residential mortgage 7 4 (1 ) — 10 Home equity loans 43 (2 ) (10 ) 6 37 Consumer direct loans 28 11 (17 ) 4 26 Credit cards 44 23 (24 ) 3 46 Consumer indirect loans 20 6 (15 ) 8 19 Total consumer loans 142 42 (67 ) 21 138 Total ALLL — continuing operations 877 124 (a) (151 ) 37 887 Discontinued operations 16 2 (7 ) 3 14 Total ALLL — including discontinued operations $ 893 $ 126 $ (158 ) $ 40 $ 901 (a) Excludes a provision for losses on lending-related commitments of $1 million . Six months ended June 30, 2017 : in millions December 31, 2016 Provision Charge-offs Recoveries June 30, 2017 Commercial and Industrial $ 508 $ 85 $ (72 ) $ 7 $ 528 Commercial real estate: Real estate — commercial mortgage 144 3 (3 ) — 144 Real estate — construction 22 5 — 1 28 Total commercial real estate loans 166 8 (3 ) 1 172 Commercial lease financing 42 4 (8 ) 2 40 Total commercial loans 716 97 (83 ) 10 740 Real estate — residential mortgage 17 (9 ) (2 ) 3 9 Home equity loans 54 (3 ) (17 ) 8 42 Consumer direct loans 24 16 (18 ) 3 25 Credit cards 38 26 (23 ) 3 44 Consumer indirect loans 9 9 (16 ) 8 10 Total consumer loans 142 39 (76 ) 25 130 Total ALLL — continuing operations 858 136 (a) (159 ) 35 870 Discontinued operations 24 3 (10 ) 4 21 Total ALLL — including discontinued operations $ 882 $ 139 $ (169 ) $ 39 $ 891 (a) Excludes a credit for losses on lending-related commitments of $7 million
Allowance for Loan and Lease Losses and Corresponding Loan Balances	A breakdown of the individual and collective ALLL and the corresponding loan balances as of June 30, 2018 , follows: Allowance Outstanding June 30, 2018 Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired Loans Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired in millions Commercial and industrial $ 7 $ 533 $ 2 $ 44,569 $ 187 $ 44,325 $ 57 Commercial real estate: Commercial mortgage — 136 3 14,162 20 13,930 212 Construction — 28 — 1,736 — 1,733 3 Total commercial real estate loans — 164 3 15,898 20 15,663 215 Commercial lease financing — 40 — 4,509 — 4,509 — Total commercial loans 7 737 5 64,976 207 64,497 272 Real estate — residential mortgage 4 5 1 5,452 48 5,071 333 Home equity loans 10 26 1 11,519 125 11,374 20 Consumer direct loans — 26 — 1,785 4 1,777 4 Credit cards — 46 — 1,094 3 1,091 — Consumer indirect loans 3 16 — 3,396 35 3,361 — Total consumer loans 17 119 2 23,246 215 22,674 357 Total ALLL — continuing operations 24 856 7 88,222 422 87,171 629 Discontinued operations 3 11 — 1,194 (a) 21 1,173 (a) — Total ALLL — including discontinued operations $ 27 $ 867 $ 7 $ 89,416 $ 443 $ 88,344 $ 629 (a) Amount includes $2 million of loans carried at fair value that are excluded from ALLL consideration. A breakdown of the individual and collective ALLL and the corresponding loan balances as of December 31, 2017 , follows: Allowance Outstanding December 31, 2017 Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired Loans Individually Evaluated for Impairment Collectively Evaluated for Impairment Purchased Credit Impaired in millions Commercial and Industrial $ 6 $ 520 $ 3 $ 41,859 $ 136 $ 41,640 $ 83 Commercial real estate: Commercial mortgage — 131 2 14,088 12 13,828 248 Construction — 30 — 1,960 — 1,934 26 Total commercial real estate loans — 161 2 16,048 12 15,762 274 Commercial lease financing — 43 — 4,826 — 4,826 — Total commercial loans 6 724 5 62,733 148 62,228 357 Real estate — residential mortgage 5 2 — 5,483 49 5,079 355 Home equity loans 9 33 1 12,028 117 11,889 22 Consumer direct loans — 28 — 1,794 4 1,786 4 Credit cards — 44 — 1,106 2 1,104 — Consumer indirect loans 3 17 — 3,261 34 3,227 — Total consumer loans 17 124 1 23,672 206 23,085 381 Total ALLL — continuing operations 23 848 6 86,405 354 85,313 738 Discontinued operations 3 13 — 1,314 (a) 21 1,293 (a) — Total ALLL — including discontinued operations $ 26 $ 861 $ 6 $ 87,719 $ 375 $ 86,606 $ 738 (a) Amount includes $2 million of loans carried at fair value that are excluded from ALLL consideration.
Changes in Liability for Credit Losses on Lending Related Commitments	Changes in the liability for credit losses on unfunded lending-related commitments are summarized as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of period $ 60 $ 48 $ 57 $ 55 Provision (credit) for losses on lending-related commitments (2 ) — 1 (7 ) Balance at end of period $ 58 $ 48 $ 58 $ 48
Schedule of Changes in Outstanding Unpaid Principal Balance, Carrying Amount, and Accretable Yield for PCI Loans	The following tables present the roll-forward of the accretable yield and the beginning and ending outstanding unpaid principal balance and carrying amount of all PCI loans for the three and six months ended June 30, 2018 , and the twelve months ended December 31, 2017 . Three Months Ended June 30, Six Months Ended June 30, 2018 2018 in millions Accretable Yield Carrying Amount Outstanding Unpaid Principal Balance Accretable Yield Carrying Amount Outstanding Unpaid Principal Balance Balance at beginning of period $ 132 $ 812 $ 930 $ 131 $ 738 $ 803 Additions — — Accretion (11 ) (23 ) Net reclassifications from nonaccretable to accretable 6 28 Payments received, net (6 ) (15 ) Disposals — — Balance at end of period $ 121 $ 622 $ 669 $ 121 $ 622 $ 669 Twelve Months Ended December 31, 2017 in millions Accretable Yield Carrying Amount Outstanding Unpaid Principal Balance Balance at beginning of period $ 197 $ 865 $ 1,002 Additions (32 ) Accretion (44 ) Net reclassifications from nonaccretable to accretable 15 Payments received, net (4 ) Disposals (1 ) Balance at end of period $ 131 $ 738 $ 803

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value of Direct and Indirect Investments, Related Unfunded Commitments and Financial Support Provided	The following table presents the fair value of our direct and indirect principal investments and related unfunded commitments at June 30, 2018 , as well as financial support provided for the three and six months ended June 30, 2018 , and June 30, 2017 . Financial support provided Three months ended June 30, Six months ended June 30, June 30, 2018 2018 2017 2018 2017 in millions Fair Value Unfunded Commitments Funded Commitments Funded Other Funded Commitments Funded Other Funded Commitments Funded Other Funded Commitments Funded Other INVESTMENT TYPE Direct investments (a) $ 13 — — — — — — — — $ — Indirect investments (measured at NAV) 109 $ 28 — — $ — — $ 1 — $ 1 — Total $ 122 $ 28 — — $ — — $ 1 — $ 1 $ — (a) Our direct investments consist of equity and debt investments directly in independent business enterprises. Operations of the business enterprises are handled by management of the portfolio company. The purpose of funding these enterprises is to provide financial support for business development and acquisition strategies. We infuse equity capital based on an initial contractual cash contribution and later from additional requests on behalf of the companies’ management. (b) Our indirect investments consist of buyout funds, venture capital funds, and fund of funds. These investments are generally not redeemable. Instead, distributions are received through the liquidation of the underlying investments of the fund. An investment in any one of these funds typically can be sold only with the approval of the fund’s general partners. We estimate that the underlying investments of the funds will be liquidated over a period of one to six years
Fair Value of Assets and Liabilities Measured on Recurring Basis	The following tables present these assets and liabilities at June 30, 2018 , and December 31, 2017 . June 30, 2018 December 31, 2017 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total in millions ASSETS MEASURED ON A RECURRING BASIS Trading account assets: U.S. Treasury, agencies and corporations — $ 537 — $ 537 — 615 — 615 States and political subdivisions — 36 — 36 — 37 — 37 Other mortgage-backed securities — 137 — 137 — 104 — 104 Other securities — 107 — 107 — 65 — 65 Total trading account securities — 817 — 817 — 821 — 821 Commercial loans — 16 — 16 — 15 — 15 Total trading account assets — 833 — 833 — 836 — 836 Securities available for sale: U.S. Treasury, agencies and corporations — 146 — 146 — 157 — 157 States and political subdivisions — 7 — 7 — 9 — 9 Agency residential collateralized mortgage obligations — 13,894 — 13,894 — 14,660 — 14,660 Agency residential mortgage-backed securities — 1,367 — 1,367 — 1,439 — 1,439 Agency commercial mortgage-backed securities — 1,933 — 1,933 — 1,854 — 1,854 Other securities — — $ 20 20 — — 20 20 Total securities available for sale — 17,347 20 17,367 — 18,119 20 18,139 Other investments: Principal investments: Direct — — 13 13 — — 13 13 Indirect (measured at NAV) (a) — — — 109 — — — 124 Total principal investments — — 13 122 — — 13 137 Equity investments: Direct — — 7 7 — 4 3 7 Direct (measured at NAV) (a) — — — 1 — — — — Total equity investments — — 7 8 — 4 3 7 Total other investments — — 20 130 — 4 16 144 Loans, net of unearned income — — 3 3 — — 2 2 Loans held for sale — 58 — 58 — 70 1 71 Derivative assets: Interest rate — 338 5 343 — 713 9 722 Foreign exchange $ 84 32 — 116 $ 100 $ 30 $ — $ 130 Commodity — 494 — 494 — 255 — 255 Credit — — — — — — 1 1 Other — 1 3 4 — 1 3 4 Derivative assets 84 865 8 957 100 999 13 1,112 Netting adjustments (b) — — — (219 ) — — — (443 ) Total derivative assets 84 865 8 738 100 999 13 669 Accrued income and other assets — — — — — — — — Total assets on a recurring basis at fair value $ 84 $ 19,103 $ 51 $ 19,129 $ 100 $ 20,028 $ 52 $ 19,861 LIABILITIES MEASURED ON A RECURRING BASIS Bank notes and other short-term borrowings: Short positions $ 6 $ 633 — $ 639 $ 72 $ 562 $ — $ 634 Derivative liabilities: Interest rate — 423 — 423 — 520 — 520 Foreign exchange 73 30 — 103 98 26 — 124 Commodity — 484 — 484 — 246 — 246 Credit — 3 9 12 — 4 — 4 Other — 2 — 2 — 13 — 13 Derivative liabilities 73 942 9 1,024 98 809 — 907 Netting adjustments (b) — — — (598 ) — — — (616 ) Total derivative liabilities 73 942 9 426 98 809 — 291 Accrued expense and other liabilities — — — — — — — — Total liabilities on a recurring basis at fair value $ 79 $ 1,575 9 $ 1,065 $ 170 $ 1,371 $ — $ 925 (a) Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the consolidated balance sheet. (b)
Change in Fair Values of Level 3 Financial Instruments	The following table shows the components of the change in the fair values of our Level 3 financial instruments for the three and six months ended June 30, 2018 , and June 30, 2017 . in millions Beginning of Period Balance Gains (Losses) Included in Other Comprehensive Income Gains (Losses) Included in Earnings Purchases Sales Settlements Transfers Other Transfers into Level 3 (a) Transfers out of Level 3 (a) End of Period Balance Unrealized Gains (Losses) Included in Earnings Six months ended June 30, 2018 Securities available for sale Other securities $ 20 $ — — — — — — — — $ 20 — Other investments Principal investments Direct 13 — $ — (b) 1 (1 ) — — — — 13 $ 1 (b) Equity investments Direct 3 — — — — — — $ 4 — 7 — Loans held for sale 1 — — — (1 ) — — — — — — Loans held for investment 2 — — — — — 1 — — 3 — Derivative instruments (c) Interest rate 9 — (2 ) (d) 1 (2 ) — — 4 (e) $ (5 ) (e) 5 — Credit 1 — (20 ) (d) — — $ 10 — — — (9 ) — Other (f) 3 — — — — — — — — 3 — Three months ended June 30, 2018 Securities available for sale Other securities $ 20 $ — — — — — — — $ — $ 20 — Other investments Principal investments Direct 12 — $ 1 (b) 1 (1 ) — — — — 13 2 (b) Equity investments Direct 7 — — — — — — — — 7 — Loans held for sale 1 — — — (1 ) — — — — — — Loans held for investment 2 — — — — — 1 — — 3 — Derivative instruments (c) Interest rate 4 — (1 ) (d) — (2 ) — — 4 (e) — (e) 5 — Credit — — (15 ) (d) — — $ 6 — — — (9 ) — Other (f) 3 — — — — — — — — 3 — in millions Beginning of Period Balance Gains (Losses) Included in Other Comprehensive Income Gains (Losses) Included in Earnings Purchases Sales Settlements Transfers Other Transfers into Level 3 (a) Transfers out of Level 3 (a) End of Period Balance Unrealized Gains (Losses) Included in Earnings Six months ended June 30, 2017 Securities available for sale Other securities $ 17 3 — — — — — — — $ 20 — Other investments Principal investments Direct 27 $ — $ (5 ) (b) — $ (7 ) — — — — 15 $ (3 ) (b) Derivative instruments (c) Interest rate 7 — — — — — — $ 12 (e) $ (3 ) (e) 16 — Credit 1 — (7 ) (d) — — $ 7 — — — 1 — Other (f) 2 — — — — — $ 2 — — 4 — Three months ended June 30, 2017 Securities available for sale Other securities $ 17 3 — — — — — — — $ 20 — Other investments Principal investments Direct 21 $ — $ (3 ) (b) — $ (3 ) — — — — 15 $ 3 (b) Derivative instruments (c) Interest rate 5 — — — — — — $ 11 (e) $ — (e) 16 — Credit 1 — (4 ) (d) — — $ 4 — — — 1 — Other (f) 4 — — $ — — — $ — — — 4 — (a) Our policy is to recognize transfers into and transfers out of Level 3 as of the end of the reporting period. (b) Realized and unrealized gains and losses on principal investments are reported in “other income” on the income statement. (c) Amounts represent Level 3 derivative assets less Level 3 derivative liabilities. (d) Realized and unrealized gains and losses on derivative instruments are reported in “corporate services income” and “other income” on the income statement. (e) Certain derivatives previously classified as Level 2 were transferred to Level 3 because Level 3 unobservable inputs became significant. Certain derivatives previously classified as Level 3 were transferred to Level 2 because Level 3 unobservable inputs became less significant. (f)
Assets and Liabilities Measured at Fair Value on Nonrecurring Basis	The following table presents our assets measured at fair value on a nonrecurring basis at June 30, 2018 , and December 31, 2017 : June 30, 2018 December 31, 2017 in millions Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ASSETS MEASURED ON A NONRECURRING BASIS Impaired loans and leases — $ 3 $ 71 $ 74 — — $ 9 $ 9 Accrued income and other assets — — 2 2 — $ 5 133 (a) 138 Total assets on a nonrecurring basis at fair value — $ 3 $ 73 $ 76 — $ 5 $ 142 $ 147 (a) At December 31, 2017, we recorded $31 million of impairment related to $119 million
Quantitative Information about Level 3 Fair Value Measurements	The range and weighted average of the significant unobservable inputs used to fair value our material Level 3 recurring and nonrecurring assets at June 30, 2018 , and December 31, 2017 , along with the valuation techniques used, are shown in the following table: June 30, 2018 Fair Value of Level 3 Assets Valuation Technique Significant Unobservable Input Range (Weighted-Average) dollars in millions Recurring Other investments — principal investments — direct: $ 13 Individual analysis of the condition of each investment Debt instruments EBITDA multiple N/A (6.93) Equity instruments of private companies EBITDA multiple N/A (6.93) Nonrecurring Impaired loans 71 Fair value of underlying collateral Discount 0.00 - 75.00% (22.00%) December 31, 2017 Fair Value of Level 3 Assets Valuation Technique Significant Unobservable Input Range (Weighted-Average) dollars in millions Recurring Other investments — principal investments — direct: $ 13 Individual analysis of the condition of each investment Debt instruments EBITDA multiple N/A (6.00) Equity instruments of private companies EBITDA multiple N/A (6.00) Nonrecurring Impaired loans 9 Fair value of underlying collateral Discount 0.00 - 50.00% (23.00%)
Fair Value Disclosures of Financial Instruments	The levels in the fair value hierarchy ascribed to our financial instruments and the related carrying amounts at June 30, 2018 , and December 31, 2017 , are shown in the following tables. Assets and liabilities are further arranged by measurement category. June 30, 2018 Fair Value in millions Carrying Amount Level 1 Level 2 Level 3 Measured at NAV Netting Adjustment Total ASSETS (by measurement category) Fair value - net income Trading account assets (b) $ 833 — $ 833 — — — $ 833 Other investments (b) 709 — — $ 599 $ 110 — 709 Loans, net of unearned income (d) 3 — — 3 — — 3 Loans held for sale (b) 58 — 58 — — — 58 Derivative assets - trading (b) 690 $ 81 828 8 — $ (227 ) (f) 690 Fair value - OCI Securities available for sale (b) 17,367 — 17,347 $ 20 — — 17,367 Derivative assets - hedging (b) 48 3 37 — — 8 (f) 48 Amortized cost Held-to-maturity securities (c) 12,277 — 11,735 — — — 11,735 Loans, net of unearned income (d) 87,332 — — 84,969 — — 84,969 Loans held for sale (b) 1,360 — — 1,360 — — 1,360 Other Cash and short-term investments (a) 3,430 3,430 — — — — 3,430 LIABILITIES (by measurement category) Fair value - net income Derivative liabilities - trading (b) $ 426 $ 73 $ 940 9 — $ (596 ) (f) $ 426 Fair value - OCI Derivative liabilities - hedging (b) — — 1 — — (1 ) (f) — Amortized cost Time deposits (e) 12,490 — 12,557 — — — 12,557 Short-term borrowings (a) 2,306 $ 6 2,300 — — — 2,306 Long-term debt (e) 13,853 12,708 1,173 — — — 13,881 Other Deposits with no stated maturity (a) 92,058 — 92,058 — — — 92,058 December 31, 2017 Fair Value in millions Carrying Amount Level 1 Level 2 Level 3 Measured at NAV Netting Adjustment Total ASSETS (by measurement category) Fair value - net income Trading account assets (b) $ 836 — $ 836 — — — $ 836 Other investments (b) 726 — 4 $ 598 $ 124 — 726 Loans, net of unearned income (d) 2 — — 2 — — 2 Loans held for sale (b) 71 — 70 1 — — 71 Derivative assets - trading (b) 681 $ 99 918 13 — $ (349 ) (f) 681 Fair value - OCI Securities available for sale (b) 18,139 — 18,119 20 — — 18,139 Derivative assets - hedging (b) (12 ) 1 81 — — (94 ) (f) (12 ) Amortized cost Held-to-maturity securities (c) 11,830 — 11,565 — — — 11,565 Loans, net of unearned income (d) 85,526 — — 84,003 — — 84,003 Loans held for sale (b) 1,036 — — 1,036 — — 1,036 Other Cash and short-term investments (a) 5,118 5,118 — — — — 5,118 LIABILITIES (by measurement category) Fair value - net income Derivative liabilities - trading (b) $ 289 $ 94 $ 763 — — $ (568 ) (f) $ 289 Fair value - OCI Derivative liabilities - hedging (b) 2 4 46 — — (48 ) (f) 2 Amortized cost Time deposits (e) 11,647 — 11,750 — — — 11,750 Short-term borrowings (a) 1,011 72 939 — — — 1,011 Long-term debt (e) 14,333 13,407 $ 1,219 — — — 14,626 Other Deposits with no stated maturity (a) 93,588 — 93,588 — — — 93,588 Valuation Methods and Assumptions (a) Fair value equals or approximates carrying amount. The fair value of deposits with no stated maturity does not take into consideration the value ascribed to core deposit intangibles. (b) Information pertaining to our methodology for measuring the fair values of these assets and liabilities is included in the sections entitled “Qualitative Disclosures of Valuation Techniques” and “Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis” in this Note. Investments accounted for under the cost method (or cost less impairment adjusted for observable price changes for certain equity investments) are classified as Level 3 assets. These investments are not actively traded in an open market as sales for these types of investments are rare. The carrying amount of the investments carried at cost are adjusted for declines in value if they are considered to be other-than-temporary (or due to observable orderly transactions of the same issuer for equity investments eligible for the cost less impairment measurement alternative). These adjustments are included in “other income” on the income statement. (c) Fair values of held-to-maturity securities are determined by using models that are based on security-specific details, as well as relevant industry and economic factors. The most significant of these inputs are quoted market prices, interest rate spreads on relevant benchmark securities, and certain prepayment assumptions. We review the valuations derived from the models to ensure that they are reasonable and consistent with the values placed on similar securities traded in the secondary markets. (d) The fair value of loans is based on the present value of the expected cash flows. The projected cash flows are based on the contractual terms of the loans, adjusted for prepayments and use of a discount rate based on the relative risk of the cash flows, taking into account the loan type, maturity of the loan, liquidity risk, servicing costs, and a required return on debt and capital. In addition, an incremental liquidity discount is applied to certain loans, using historical sales of loans during periods of similar economic conditions as a benchmark. The fair value of loans includes lease financing receivables at their aggregate carrying amount, which is equivalent to their fair value. (e) Fair values of time deposits and long-term debt are based on discounted cash flows utilizing relevant market inputs. (f)

Securities (Tables)

Securities (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Details of Securities	The amortized cost, unrealized gains and losses, and approximate fair value of our securities available for sale and held-to-maturity securities are presented in the following tables. Gross unrealized gains and losses represent the difference between the amortized cost and the fair value of securities on the balance sheet as of the dates indicated. Accordingly, the amount of these gains and losses may change in the future as market conditions change. June 30, 2018 December 31, 2017 in millions Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value SECURITIES AVAILABLE FOR SALE U.S. Treasury, agencies, and corporations $ 150 — $ 4 $ 146 $ 159 $ — $ 2 $ 157 States and political subdivisions 7 — — 7 9 — — 9 Agency residential collateralized mortgage obligations 14,435 $ 5 546 13,894 14,985 10 335 14,660 Agency residential mortgage-backed securities 1,407 2 42 1,367 1,456 3 20 1,439 Agency commercial mortgage-backed securities 2,041 — 108 1,933 1,920 — 66 1,854 Other securities 17 3 — 20 17 3 — 20 Total securities available for sale $ 18,057 $ 10 $ 700 $ 17,367 $ 18,546 $ 16 $ 423 $ 18,139 HELD-TO-MATURITY SECURITIES Agency residential collateralized mortgage obligations $ 7,699 1 $ 372 $ 7,328 $ 8,055 $ — $ 224 $ 7,831 Agency residential mortgage-backed securities 531 $ — 17 514 574 1 4 571 Agency commercial mortgage-backed securities 4,032 — 154 3,878 3,186 6 44 3,148 Other securities 15 — — 15 15 — — 15 Total held-to-maturity securities $ 12,277 $ 1 $ 543 $ 11,735 $ 11,830 $ 7 $ 272 $ 11,565
Schedule of Unrealized Loss on Investments	The following table summarizes our securities that were in an unrealized loss position as of June 30, 2018 , and December 31, 2017 . Duration of Unrealized Loss Position Less than 12 Months 12 Months or Longer Total in millions Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses June 30, 2018 Securities available for sale: U.S Treasury, agencies, and corporations $ 39 $ 1 $ 107 $ 3 $ 146 $ 4 Agency residential collateralized mortgage obligations 5,742 141 7,230 405 12,972 546 Agency residential mortgage-backed securities 338 10 873 32 1,211 42 Agency commercial mortgage-backed securities 192 9 1,593 99 1,785 108 Held-to-maturity securities: Agency residential collateralized mortgage obligations 2,058 65 5,156 307 7,214 372 Agency residential mortgage-backed securities 330 10 184 7 514 17 Agency commercial mortgage-backed securities 3,030 104 477 50 3,507 154 Other securities (a) 9 — — — 9 — Total temporarily impaired securities $ 11,738 $ 340 $ 15,620 $ 903 $ 27,358 $ 1,243 December 31, 2017 Securities available for sale: U.S. Treasury, agencies, and corporations $ 41 $ — 116 2 $ 157 $ 2 Agency residential collateralized mortgage obligations 6,153 74 $ 7,270 $ 261 13,423 335 Agency residential mortgage-backed securities 666 7 702 13 1,368 20 Agency commercial mortgage-backed securities 205 4 1,649 62 1,854 66 Held-to-maturity securities: Agency residential collateralized mortgage obligations 2,201 27 5,599 197 7,800 224 Agency residential mortgage-backed securities 252 1 206 3 458 4 Agency commercial mortgage-backed securities 1,470 12 495 32 1,965 44 Other securities (a) 3 — 4 — 7 — Total temporarily impaired securities $ 10,991 $ 125 $ 16,041 $ 570 $ 27,032 $ 695 (a) Gross unrealized losses totaled less than $1 million for other securities held-to maturity at June 30, 2018 , and December 31, 2017 .
Cumulative Credit Portion of Impairments on Debt Securities	As shown in the following table, we did not have any impairment losses recognized in earnings for the three and six months ended June 30, 2018 , and June 30, 2017 . Six months ended June 30, 2018 in millions Balance at December 31, 2017 $ 4 Impairment recognized in earnings — Balance at June 30, 2018 $ 4
Securities by Maturity	The following table shows our securities by remaining maturity. CMOs and other mortgage-backed securities available for sale portfolio and held-to-maturity portfolio are presented based on their expected average lives. The remaining securities, in both the available-for-sale and held-to-maturity portfolios, are presented based on their remaining contractual maturity. Actual maturities may differ from expected or contractual maturities since borrowers have the right to prepay obligations with or without prepayment penalties. Securities Available for Sale Held to Maturity Securities June 30, 2018 Amortized Cost Fair Value Amortized Cost Fair Value in millions Due in one year or less $ 113 $ 113 $ 43 $ 42 Due after one through five years 12,105 11,602 6,653 6,410 Due after five through ten years 5,823 5,636 5,581 5,283 Due after ten years 16 16 — — Total $ 18,057 $ 17,367 $ 12,277 $ 11,735

Derivatives and Hedging Activ37

Derivatives and Hedging Activities (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments	The following table summarizes the fair values of our derivative instruments on a gross and net basis as of June 30, 2018 , and December 31, 2017 . The derivative asset and liability balances are presented on a gross basis, prior to the application of bilateral collateral and master netting agreements, but after the variation margin payments with central clearing organizations have been applied as settlement, as applicable. Total derivative assets and liabilities are adjusted to take into account the impact of legally enforceable master netting agreements that allow us to settle all derivative contracts with a single counterparty on a net basis and to offset the net derivative position with the related cash collateral. Securities collateral related to legally enforceable master netting agreements is not offset on the balance sheet. Our derivative instruments are included in “accrued income and other assets” or “accrued expenses and other liabilities” on the balance sheet, as follows: June 30, 2018 December 31, 2017 Fair Value Fair Value in millions Notional Amount Derivative Assets Derivative Liabilities Notional Amount Derivative Assets Derivative Liabilities Derivatives designated as hedging instruments: Interest rate $ 28,918 $ 37 $ 2 $ 26,176 $ 81 $ 46 Foreign exchange 256 3 — 302 1 4 Total 29,174 40 2 26,478 82 50 Derivatives not designated as hedging instruments: Interest rate 66,309 306 421 61,390 641 474 Foreign exchange 9,378 113 103 8,317 129 120 Commodity 2,165 494 484 1,687 255 246 Credit 381 — 12 315 1 4 Other (a) 1,244 4 2 2,006 4 13 Total 79,477 917 1,022 73,715 1,030 857 Netting adjustments (b) — (219 ) (598 ) — (443 ) (616 ) Net derivatives in the balance sheet 108,651 738 426 100,193 669 291 Other collateral (c) — (2 ) (69 ) — (5 ) (84 ) Net derivative amounts $ 108,651 $ 736 $ 357 $ 100,193 $ 664 $ 207 (a) Other derivatives include interest rate lock commitments and forward sale commitments related to our residential mortgage banking activities, forward purchase and sales contracts consisting of contractual commitments associated with “to be announced” securities and when issued securities, and when-issued security transactions in connection with an “at-the-market” equity offering program. (b) Netting adjustments represent the amounts recorded to convert our derivative assets and liabilities from a gross basis to a net basis in accordance with the applicable accounting guidance. (c)
Pre-Tax Net Gains (Losses) on Fair Value Hedges	The following table summarizes the amounts that were recorded on the balance sheet as of June 30, 2018 , related to cumulative basis adjustments for fair value hedges. June 30, 2018 in millions Balance sheet line item in which the hedge item is included Carrying amount of hedged item (a) Hedge accounting basis adjustment (b) Interest rate contracts Long-term debt $ 9,481 $ (104 ) Interest rate contracts Certificate of deposit ($100,000 or more) 347 — Interest rate contracts Other time deposits 179 — (a) The carrying amount represents the portion of the liability designated as the hedged item. (b) Basis adjustment includes $11 million
Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location	The following tables summarize the effect of fair value and cash flow hedge accounting on the income statement for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 . Location and amount of net gains (losses) recognized in income on fair value and cash flow hedging relationships (a) in millions Interest expense – long-term debt Interest income – loans Interest expense - deposits Other income Three months ended June 30, 2018 Total amounts presented in the consolidated statement of income $ (102 ) $ 1,000 $ (112 ) $ 99 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items 22 — 1 — Recognized on derivatives designated as hedging instruments (25 ) — — — Net income (expense) recognized on fair value hedges (3 ) — 1 — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income 1 (25 ) — — Net income (expense) recognized on cash flow hedges $ 1 $ (25 ) — — Three months ended June 30, 2017 Total amounts presented in the consolidated statement of income $ (74 ) $ 948 $ (66 ) $ 85 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items — — — (5 ) Recognized on derivatives designated as hedging instruments 14 — — 5 Net income (expense) recognized on fair value hedges 14 — — — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income (1 ) 5 — — Gains (losses) (before tax) recognized in income for hedge ineffectiveness — — — — Net income (expense) recognized on cash flow hedges $ (1 ) $ 5 — — Location and amount of net gains (losses) recognized in income on fair value and cash flow hedging relationships (a) in millions Interest expense – long-term debt Interest income – loans Interest expense - deposits Other income Six months ended June 30, 2018 Total amounts presented in the consolidated statement of income $ (194 ) $ 1,940 $ (203 ) $ 120 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items 93 — 1 — Recognized on derivatives designated as hedging instruments (94 ) — — — Net income (expense) recognized on fair value hedges (1 ) — 1 — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income — (27 ) — — Net income (expense) recognized on cash flow hedges $ — $ (27 ) — — Six months ended June 30, 2017 Total amounts presented in the consolidated statement of income $ (142 ) $ 1,825 $ (124 ) $ 117 Net gains (losses) on fair value hedging relationships Interest contracts Recognized on hedged items — — — 30 Recognized on derivatives designated as hedging instruments 32 — — (30 ) Net income (expense) recognized on fair value hedges 32 — — — Net gain (loss) on cash flow hedging relationships Interest contracts Realized gains (losses) (pre-tax) reclassified from AOCI into net income (2 ) 20 — — Gains (losses) (before tax) recognized in income for hedge ineffectiveness — — — — Net income (expense) recognized on cash flow hedges $ (2 ) $ 20 — — (a) Prior period gain or loss amounts were not restated to conform to the new hedge accounting guidance adopted in 2018.
Derivative Instrument Cash Flow Hedge Earning Recognized by Income Statement Location	The following tables summarize the pre-tax net gains (losses) on our cash flow and net investment hedges for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 , and where they are recorded on the income statement. The table includes net gains (losses) recognized in OCI during the period and net gains (losses) reclassified from OCI into income during the current period. in millions Net Gains (Losses) Recognized in OCI Income Statement Location of Net Gains (Losses) Reclassified From OCI Into Income Net Gains (Losses) Reclassified From OCI Into Income (a) Net Gains (Losses) Recognized in Other Income (a) Three months ended June 30, 2018 Cash Flow Hedges Interest rate $ (58 ) Interest income — Loans $ (25 ) $ — Interest rate 2 Interest expense — Long-term debt 1 — Interest rate 1 Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts 10 Other Income — — Total $ (45 ) $ (24 ) $ — Three months ended June 30, 2017 Cash Flow Hedges Interest rate $ 22 Interest income — Loans $ 5 $ — Interest rate — Interest expense — Long-term debt (1 ) — Interest rate — Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts (7 ) Other Income — — Total $ 15 $ 4 $ — in millions Net Gains (Losses) Recognized in OCI Income Statement Location of Net Gains (Losses) Reclassified From OCI Into Income Net Gains (Losses) Reclassified From OCI Into Income (a) Net Gains (Losses) Recognized in Other Income (a) Six months ended June 30, 2018 Cash Flow Hedges Interest rate $ (146 ) Interest income — Loans $ (27 ) $ — Interest rate 4 Interest expense — Long-term debt — — Interest rate 1 Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts 10 Other Income — — Total $ (131 ) $ (27 ) $ — Six months ended June 30, 2017 Cash Flow Hedges Interest rate $ — Interest income — Loans $ 20 $ — Interest rate — Interest expense — Long-term debt (2 ) — Interest rate — Investment banking and debt placement fees — — Net Investment Hedges Foreign exchange contracts (10 ) Other Income — — Total $ (10 ) $ 18 $ — (a)
Pre-Tax Net Gains (Losses) on Derivatives Not Designated as Hedging Instruments	The following tables summarize the pre-tax net gains (losses) on our derivatives that are not designated as hedging instruments for the three- and six- month periods ended June 30, 2018 , and June 30, 2017 , and where they are recorded on the income statement. Three months ended June 30, 2018 Three months ended June 30, 2017 in millions Corporate services income Consumer mortgage income Other income Total Corporate services income Consumer mortgage income Other income Total NET GAINS (LOSSES) Interest rate $ 11 $ — $ — $ 11 $ 10 — $ (1 ) $ 9 Foreign exchange 11 — — 11 10 — — 10 Commodity 3 — — 3 1 — — 1 Credit — — (14 ) (14 ) — — (5 ) (5 ) Other — — 16 16 — $ 2 (10 ) (8 ) Total net gains (losses) $ 25 $ — $ 2 $ 27 $ 21 $ 2 $ (16 ) $ 7 Six months ended June 30, 2018 Six months ended June 30, 2017 in millions Corporate services income Consumer mortgage income Other income Total Corporate services income Consumer mortgage income Other income Total NET GAINS (LOSSES) Interest rate $ 20 $ — $ 2 $ 22 $ 16 — $ (2 ) $ 14 Foreign exchange 22 — — 22 21 — — 21 Commodity 6 — — 6 3 — — 3 Credit 2 — (19 ) (17 ) 1 — (10 ) (9 ) Other — — 12 12 — $ 1 (11 ) (10 ) Total net gains (losses) $ 50 $ — $ (5 ) $ 45 $ 41 $ 1 $ (23 ) $ 19
Fair Value of Derivative Assets by Type	The following table summarizes the fair value of our derivative assets by type at the dates indicated. These assets represent our gross exposure to potential loss after taking into account the effects of bilateral collateral and master netting agreements and other means used to mitigate risk. in millions June 30, 2018 December 31, 2017 Interest rate $ 215 $ 401 Foreign exchange 66 77 Commodity 326 163 Credit — 1 Other 4 4 Derivative assets before collateral 611 646 Less: Related collateral (127 ) (23 ) Total derivative assets $ 738 $ 669
Fair Value of Credit Derivatives Purchased and Sold	The following table summarizes the fair value of our credit derivatives purchased and sold by type as of June 30, 2018 , and December 31, 2017 . The fair value of credit derivatives presented below does not take into account the effects of bilateral collateral or master netting agreements. June 30, 2018 December 31, 2017 in millions Purchased Sold Net Purchased Sold Net Single-name credit default swaps $ (1 ) — $ (1 ) $ (1 ) — $ (1 ) Traded credit default swap indices (1 ) — (1 ) (2 ) — (2 ) Other — (1 ) (1 ) — — — Total credit derivatives $ (2 ) (1 ) $ (3 ) $ (3 ) — $ (3 )
Credit Derivatives Sold and Held	The following table provides information on the types of credit derivatives sold by us and held on the balance sheet at June 30, 2018 , and December 31, 2017 . The notional amount represents the maximum amount that the seller could be required to pay. The payment/performance risk assessment is based on the default probabilities for the underlying reference entities’ debt obligations using a Moody’s credit ratings matrix known as Moody’s “Idealized” Cumulative Default Rates. The payment/performance risk shown in the table represents a weighted-average of the default probabilities for all reference entities in the respective portfolios. These default probabilities are directly correlated to the probability that we will have to make a payment under the credit derivative contracts. June 30, 2018 December 31, 2017 dollars in millions Notional Amount Average Term (Years) Payment / Performance Risk Notional Amount Average Term (Years) Payment / Performance Risk Other $ 21 10.38 14.13 % $ 15 3.08 6.64 % Total credit derivatives sold $ 21 — — $ 15 — —
Credit Risk Contingent Feature	The following table summarizes the additional cash and securities collateral that KeyBank would have been required to deliver under the ISDA Master Agreements had the credit risk contingent features been triggered for the derivative contracts in a net liability position as of June 30, 2018 , and December 31, 2017 . The additional collateral amounts were calculated based on scenarios under which KeyBank’s ratings are downgraded one, two, or three ratings as of June 30, 2018 , and December 31, 2017 , and take into account all collateral already posted. A similar calculation was performed for KeyCorp, and no additional collateral would have been required as of June 30, 2018 , and December 31, 2017 . For more information about the credit ratings for KeyBank and KeyCorp, see the discussion under the heading “Factors affecting liquidity” in the section entitled “Liquidity risk management” in Item 2 of this report. June 30, 2018 December 31, 2017 in millions Moody’s S&P Moody’s S&P KeyBank’s long-term senior unsecured credit ratings A3 A- A3 A- One rating downgrade $ 2 $ 2 $ 2 $ 2 Two rating downgrades 2 2 2 2 Three rating downgrades 2 2 2 2

Mortgage Servicing Assets (Tabl

Mortgage Servicing Assets (Tables)	6 Months Ended
	Jun. 30, 2018
Servicing Asset [Abstract]
Changes in Carrying Amount of Mortgage Servicing Assets	Changes in the carrying amount of residential mortgage servicing assets are summarized as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of period $ 32 $ 29 $ 31 $ 28 Servicing retained from loan sales 3 1 5 3 Purchases — — — — Amortization (1 ) (1 ) (2 ) (2 ) Balance at end of period $ 34 $ 29 $ 34 $ 29 Fair value at end of period $ 43 $ 35 $ 43 $ 35 Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Balance at beginning of period $ 435 $ 369 $ 412 $ 356 Servicing retained from loan sales 29 19 56 47 Purchases 12 7 33 14 Amortization (25 ) (22 ) (50 ) (44 ) Balance at end of period $ 451 $ 373 $ 451 $ 373 Fair value at end of period $ 646 $ 495 $ 646 $ 495
Schedule of Range and Weighted-Average of Significant Unobservable Inputs	The range and weighted average of the significant unobservable inputs used to determine the fair value of our commercial mortgage servicing assets at June 30, 2018 , and June 30, 2017 , along with the valuation techniques, are shown in the following table: dollars in millions June 30, 2018 June 30, 2017 Valuation Technique Significant Unobservable Input Range (Weighted Average) Discounted cash flow Expected defaults 1.00 - 3.00% (1.17%) 1.00 - 3.00% (1.30%) Residual cash flows discount rate 7.00 - 15.00% (9.06%) 7.00 - 15.00% (8.80%) Escrow earn rate 2.40 - 3.82% (3.10%) 1.50 - 3.10% (2.50%) Servicing cost $150 - $38,500 ($1,431) $150 - $38,500 ($1,457) Loan assumption rate 0.00 - 3.00% (1.19%) 0.00 - 3.00% (1.24%) Percentage late 0.00 - 2.00% (.22%) 0.00 - 2.00% (.29%) June 30, 2018 , and June 30, 2017 , along with the valuation techniques, are shown in the following table: dollars in millions June 30, 2018 June 30, 2017 Valuation Technique Significant Unobservable Input Range (Weighted Average) Discounted cash flow Prepayment speed 8.39 - 49.39% (9.17%) 7.85 - 21.72% (9.42%) Discount rate 8.50 - 11.00% (8.54%) 8.50 - 11.00% (8.55%) Servicing cost $76 - $4,385 ($82.38) $76 - $3,335 ($82.18)

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities Information	The assets and liabilities presented in the table below convey the size of KCDC’s direct and indirect investments at June 30, 2018 , and December 31, 2017 . As these investments represent unconsolidated VIEs, the assets and liabilities of the investments themselves are not recorded on our balance sheet. Unconsolidated VIEs in millions Total Assets Total Liabilities Maximum Exposure to Loss June 30, 2018 LIHTC investments $ 6,176 $ 2,971 $ 1,583 December 31, 2017 LIHTC investments $ 6,003 $ 2,943 $ 1,561 June 30, 2018 and December 31, 2017 . Unconsolidated VIEs in millions Total Assets Total Liabilities Maximum Exposure to Loss June 30, 2018 Indirect investments $ 22,367 $ 426 $ 137 December 31, 2017 Indirect investments $ 26,817 $ 292 $ 153

Securities Financing Activiti40

Securities Financing Activities (Tables)	6 Months Ended
	Jun. 30, 2018
Banking and Thrift [Abstract]
Summarized Securities Financing Agreements	The following table summarizes our securities financing agreements at June 30, 2018 , and December 31, 2017 : June 30, 2018 December 31, 2017 in millions Gross Amount Presented in Balance Sheet Netting Adjustments (a) Collateral (b) Net Amounts Gross Amount Presented in Balance Sheet Netting Adjustments (a) Collateral (b) Net Amounts Offsetting of financial assets: Reverse repurchase agreements $ 11 $ (11 ) $ — — $ 3 $ (3 ) — — Total $ 11 $ (11 ) $ — — $ 3 $ (3 ) — — Offsetting of financial liabilities: Repurchase agreements (c) $ 266 $ (14 ) $ (252 ) — $ 374 $ (4 ) $ (370 ) — Total $ 266 $ (14 ) $ (252 ) — $ 374 $ (4 ) $ (370 ) — (a) Netting adjustments take into account the impact of master netting agreements that allow us to settle with a single counterparty on a net basis. (b) These adjustments take into account the impact of bilateral collateral agreements that allow us to offset the net positions with the related collateral. The application of collateral cannot reduce the net position below zero. Therefore, excess collateral, if any, is not reflected above. (c)

Employee Benefits (Tables)

Employee Benefits (Tables)	6 Months Ended
	Jun. 30, 2018
Retirement Benefits [Abstract]
Net Pension Cost (Benefit) for All Funded and Unfunded Plans	The components of net pension cost (benefit) for all funded and unfunded plans are as follows: Three months ended June 30, Six months ended June 30, in millions 2018 2017 2018 2017 Interest cost on PBO $ 10 $ 12 $ 20 $ 24 Expected return on plan assets (13 ) (17 ) (26 ) (34 ) Amortization of losses 4 4 8 8 Net pension cost $ 1 $ (1 ) $ 2 $ (2 )

Trust Preferred Securities Is42

Trust Preferred Securities Issued by Unconsolidated Subsidiaries (Tables)	6 Months Ended
	Jun. 30, 2018
Banking and Thrift [Abstract]
Summary of Trust Preferred Securities, Common Stock and Related Debentures	The trust preferred securities, common stock, and related debentures are summarized as follows: dollars in millions Trust Preferred Securities, Net of Discount (a) Common Stock Principal Amount of Debentures, Net of Discount (b) Interest Rate of Trust Preferred Securities and Debentures (c) Maturity of Trust Preferred Securities and Debentures June 30, 2018 KeyCorp Capital I $ 155 $ 6 $ 161 3.052 % 2028 KeyCorp Capital II 101 4 105 6.875 2029 KeyCorp Capital III 130 4 134 7.750 2029 HNC Statutory Trust III 18 1 19 3.730 2035 Willow Grove Statutory Trust I 18 1 19 3.651 2036 HNC Statutory Trust IV 16 1 17 3.639 2037 Westbank Capital Trust II 7 — 7 4.515 2034 Westbank Capital Trust III 7 — 7 4.515 2034 Total $ 452 $ 17 $ 469 5.374 % — December 31, 2017 $ 463 $ 17 $ 480 4.977 % — (a) The trust preferred securities must be redeemed when the related debentures mature, or earlier if provided in the governing indenture. Each issue of trust preferred securities carries an interest rate identical to that of the related debenture. Certain trust preferred securities include basis adjustments related to fair value hedges totaling $44 million at June 30, 2018 , and $55 million at December 31, 2017 . See Note 7 (“ Derivatives and Hedging Activities ”) for an explanation of fair value hedges. (b) We have the right to redeem these debentures. If the debentures purchased by KeyCorp Capital I, HNC Statutory Trust III, Willow Grove Statutory Trust I, HNC Statutory Trust IV, Westbank Capital Trust II, or Westbank Capital Trust III are redeemed before they mature, the redemption price will be the principal amount, plus any accrued but unpaid interest. If the debentures purchased by KeyCorp Capital II or KeyCorp Capital III are redeemed before they mature, the redemption price will be the greater of: (i) the principal amount, plus any accrued but unpaid interest, or (ii) the sum of the present values of principal and interest payments discounted at the Treasury Rate (as defined in the applicable indenture), plus 20 basis points for KeyCorp Capital II or 25 basis points for KeyCorp Capital III, or 50 basis points in the case of redemption upon either a tax or a capital treatment event for either KeyCorp Capital II or KeyCorp Capital III, plus any accrued but unpaid interest. The principal amount of certain debentures includes basis adjustments related to fair value hedges totaling $44 million at June 30, 2018 , and $55 million at December 31, 2017 . See Note 7 (“ Derivatives and Hedging Activities ”) for an explanation of fair value hedges. The principal amount of debentures, net of discounts, is included in “long-term debt” on the balance sheet. (c)

Contingent Liabilities and Gu43

Contingent Liabilities and Guarantees (Tables)	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Guarantees	The following table shows the types of guarantees that we had outstanding at June 30, 2018 . Information pertaining to the basis for determining the liabilities recorded in connection with these guarantees is included in Note 1 (“ Summary of Significant Accounting Policies ”) under the heading “Guarantees” beginning on page 108 of our 2017 Form 10-K. June 30, 2018 Maximum Potential Undiscounted Future Payments Liability Recorded in millions Financial guarantees: Standby letters of credit $ 3,124 $ 72 Recourse agreement with FNMA 3,547 7 Residential mortgage reserve 1,454 6 Return guarantee agreement with LIHTC investors 3 3 Written put options (a) 2,764 88 Total $ 10,892 $ 176 (a)

Accumulated Other Comprehensi44

Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2018
Equity [Abstract]
Changes in AOCI	Our changes in AOCI for the three and six months ended June 30, 2018 , and June 30, 2017 , are as follows: in millions Unrealized gains (losses) on securities available for sale Unrealized gains (losses) on derivative financial instruments Foreign currency translation adjustment Net pension and postretirement benefit costs Total Balance at December 31, 2017 $ (311 ) $ (86 ) $ 9 $ (391 ) $ (779 ) Other comprehensive income before reclassification, net of income taxes (216 ) (100 ) (11 ) — (327 ) Amounts reclassified from AOCI, net of income taxes (a) — 20 — 6 26 Other amounts reclassified from AOCI, net of income taxes — — (5 ) — (5 ) Net current-period other comprehensive income, net of income taxes (216 ) (80 ) (16 ) 6 (306 ) Balance at June 30, 2018 $ (527 ) $ (166 ) $ (7 ) $ (385 ) $ (1,085 ) Balance at March 31, 2018 $ (461 ) $ (149 ) $ 7 $ (388 ) $ (991 ) Other comprehensive income before reclassification, net of income taxes (66 ) (35 ) (9 ) — (110 ) Amounts reclassified from AOCI, net of income taxes (a) — 18 — 3 21 Other amounts reclassified from AOCI, net of income taxes — — (5 ) — (5 ) Net current-period other comprehensive income, net of income taxes (66 ) (17 ) (14 ) 3 (94 ) Balance at June 30, 2018 $ (527 ) $ (166 ) $ (7 ) $ (385 ) $ (1,085 ) Balance at December 31, 2016 $ (185 ) $ (14 ) $ (3 ) $ (339 ) $ (541 ) Other comprehensive income before reclassification, net of income taxes 40 (6 ) 7 — 41 Amounts reclassified from AOCI, net of income taxes (a) — (11 ) — 5 (6 ) Net current-period other comprehensive income, net of income taxes 40 (17 ) 7 5 35 Balance at June 30, 2017 $ (145 ) $ (31 ) $ 4 $ (334 ) $ (506 ) Balance at March 31, 2017 (179 ) $ (38 ) $ (2 ) $ (335 ) $ (554 ) Other comprehensive income before reclassification, net of income taxes 34 9 6 (1 ) 48 Amounts reclassified from AOC, net of income taxes (a) — (2 ) — 2 — Net current-period other comprehensive income, net of income taxes 34 7 6 1 48 Balance at June 30, 2017 $ (145 ) $ (31 ) $ 4 $ (334 ) $ (506 ) (a)
Reclassifications Out of AOCI	Our reclassifications out of AOCI for the three and six months ended June 30, 2018 , and June 30, 2017 , are as follows: Six months ended June 30, Affected Line Item in the Statement Where Net Income is Presented in millions 2018 2017 Unrealized gains (losses) on derivative financial instruments Interest rate $ (27 ) $ 20 Interest income — Loans Interest rate — (2 ) Interest expense — Long-term debt (27 ) 18 Income (loss) from continuing operations before income taxes (7 ) 7 Income taxes $ (20 ) $ 11 Income (loss) from continuing operations Net pension and postretirement benefit costs Amortization of losses $ (8 ) $ (8 ) Personnel expense (8 ) (8 ) Income (loss) from continuing operations before income taxes (2 ) (3 ) Income taxes $ (6 ) $ (5 ) Income (loss) from continuing operations Three months ended June 30, Affected Line Item in the Statement Where Net Income is Presented in millions 2018 2017 Unrealized gains (losses) on derivative financial instruments Interest rate $ (25 ) $ 5 Interest income — Loans Interest rate 1 (1 ) Interest expense — Long-term debt (24 ) 4 Income (loss) from continuing operations before income taxes (6 ) 2 Income taxes $ (18 ) 2 Income (loss) from continuing operations Net pension and postretirement benefit costs Amortization of losses $ (4 ) (4 ) Personnel expense (4 ) (4 ) Income (loss) from continuing operations before income taxes (1 ) (2 ) Income taxes $ (3 ) $ (2 ) Income (loss) from continuing operations

Line of Business Results (Table

Line of Business Results (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Financial Information of Business Groups	Three months ended June 30, Key Community Bank Key Corporate Bank dollars in millions 2018 2017 2018 2017 SUMMARY OF OPERATIONS Net interest income (TE) $ 715 $ 676 $ 277 $ 312 Noninterest income 281 322 265 285 Total revenue (TE) (a) 996 998 542 597 Provision for credit losses 38 47 28 19 Depreciation and amortization expense 28 28 33 22 Other noninterest expense 611 607 293 275 Income (loss) from continuing operations before income taxes (TE) 319 316 188 281 Allocated income taxes and TE adjustments 75 118 21 57 Income (loss) from continuing operations 244 198 167 224 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) 244 198 167 224 Less: Net income (loss) attributable to noncontrolling interests — — — — Net income (loss) attributable to Key $ 244 $ 198 $ 167 $ 224 AVERAGE BALANCES (b) Loans and leases $ 47,984 $ 47,477 $ 39,710 $ 37,704 Total assets (a) 51,866 51,441 47,213 44,131 Deposits 80,930 79,601 21,057 21,145 OTHER FINANCIAL DATA Net loan charge-offs (b) $ 34 $ 47 $ 26 $ 19 Return on average allocated equity (b) 20.22 % 16.59 % 23.07 % 31.66 % Return on average allocated equity 20.22 16.59 23.07 31.66 Average full-time equivalent employees (c) 10,619 10,558 2,537 2,364 Six months ended June 30, Key Community Bank Key Corporate Bank dollars in millions 2018 2017 2018 2017 SUMMARY OF OPERATIONS Net interest income (TE) $ 1,403 $ 1,305 $ 549 $ 616 Noninterest income 551 583 552 559 Total revenue (TE) (a) 1,954 1,888 1,101 1,175 Provision for credit losses 86 94 42 36 Depreciation and amortization expense 57 56 67 42 Other noninterest expense 1,233 1,185 573 561 Income (loss) from continuing operations before income taxes (TE) 578 553 419 536 Allocated income taxes and TE adjustments 137 206 45 133 Income (loss) from continuing operations 441 347 374 403 Income (loss) from discontinued operations, net of taxes — — — — Net income (loss) 441 347 374 403 Less: Net income (loss) attributable to noncontrolling interests — — — (1 ) Net income (loss) attributable to Key $ 441 $ 347 $ 374 $ 404 AVERAGE BALANCES (b) Loans and leases $ 47,833 $ 47,282 $ 38,989 $ 37,696 Total assets (a) 51,736 51,215 46,386 44,128 Deposits 80,440 79,375 20,937 21,074 OTHER FINANCIAL DATA Net loan charge-offs (b) $ 76 $ 90 $ 38 $ 33 Return on average allocated equity (b) 18.43 % 14.70 % 26.21 % 28.27 % Return on average allocated equity 18.43 14.70 26.21 28.27 Average full-time equivalent employees (c) 10,642 10,511 2,540 2,374 (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 2018 2017 2018 2017 2018 2017 2018 2017 $ (12 ) $ (8 ) $ 980 $ 980 $ 7 $ 7 $ 987 $ 987 50 54 596 661 64 (8 ) 660 653 38 46 1,576 1,641 71 (1 ) 1,647 1,640 (1 ) — 65 66 (1 ) — 64 66 — 1 61 51 38 42 99 93 16 26 920 908 (26 ) (6 ) 894 902 23 19 530 616 60 (37 ) 590 579 (2 ) (5 ) 94 170 17 2 111 172 25 24 436 446 43 (39 ) 479 407 — — — — 3 5 3 5 25 24 436 446 46 (34 ) 482 412 — — — — — — — — $ 25 $ 24 $ 436 $ 446 $ 46 $ (34 ) $ 482 $ 412 $ 934 $ 1,288 $ 88,628 $ 86,469 $ 16 $ 33 $ 88,644 $ 86,502 36,932 36,181 136,011 131,753 367 738 136,378 132,491 1,960 2,050 103,947 102,796 56 (17 ) 104,003 102,779 1 — $ 60 $ 66 — $ — $ 60 $ 66 78.96 % 61.31 % 22.22 % 22.99 % 2.41 % (2.11 )% 12.78 % 10.74 % 78.96 61.31 22.22 22.99 2.58 (1.84 ) 12.86 10.87 195 342 13,351 13,264 5,025 5,080 18,376 18,344 Other Segments Total Segments Reconciling Items Key 2018 2017 2018 2017 2018 2017 2018 2017 $ (26 ) $ (12 ) $ 1,926 $ 1,909 $ 13 $ 7 $ 1,939 $ 1,916 101 102 1,204 1,244 57 (14 ) 1,261 1,230 75 90 3,130 3,153 70 (7 ) 3,200 3,146 (2 ) — 126 130 (1 ) (1 ) 125 129 1 1 125 99 78 87 203 186 39 52 1,845 1,798 (49 ) 24 1,796 1,822 37 37 1,034 1,126 42 (117 ) 1,076 1,009 (7 ) (10 ) 175 329 6 (52 ) 181 277 44 47 859 797 36 (65 ) 895 732 — — — — 5 5 5 5 44 47 859 797 41 (60 ) 900 737 — 2 — 1 — — — 1 $ 44 $ 45 $ 859 $ 796 $ 41 $ (60 ) $ 900 $ 736 $ 963 $ 1,308 $ 87,785 $ 86,286 $ 5 $ 32 $ 87,790 $ 86,318 37,130 36,403 135,252 131,746 399 869 135,651 132,615 1,840 2,040 103,217 102,489 66 (59 ) 103,283 102,430 1 $ 1 $ 114 $ 124 — — $ 114 $ 124 66.22 % 56.36 % 22.10 % 20.57 % 1.02 % (1.77 )% 12.06 % 9.70 % 66.22 56.36 22.10 20.57 1.16 (1.64 ) 12.13 9.77 259 343 13,441 13,228 5,017 5,137 18,458 18,365

Revenue from Contracts with C46

Revenue from Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table represents a disaggregation of revenue from contracts with customers, by line of business, for the three- and six- month periods ended June 30, 2018 : Three months ended June 30, 2018 dollars in millions Key Community Bank Key Corporate Bank Total Contract Revenue NONINTEREST INCOME Trust and investment services income $ 91 $ 18 $ 109 Investment banking and debt placement fees 1 67 68 Services charges on deposit accounts 78 13 91 Cards and payments income 40 29 69 Other noninterest income 5 — 5 Total revenue from contracts with customers $ 215 $ 127 $ 342 Other noninterest income (a) $ 204 Noninterest income from other segments (b) 50 Reconciling items (c) 64 Total noninterest income $ 660 (a) Noninterest income considered earned outside the scope of contracts with customers. (b) Other Segments consist of corporate treasury, our principle investing unit, and various exit portfolios. (c) Reconciling items consists primarily of the gain on the sale of, and contract revenue recognized prior to the sale of, Key Insurance and Benefits Services for the second quarter of 2018, intercompany eliminations, and items not allocated to the business segments because they do not reflect their normal operations. Refer to the Line of Business Results footnote for more information. Six months ended June 30, 2018 dollars in millions Key Community Bank Key Corporate Bank Total Contract Revenue NONINTEREST INCOME Trust and investment services income $ 179 $ 33 $ 212 Investment banking and debt placement fees 1 114 115 Services charges on deposit accounts 153 26 179 Cards and payments income 75 55 130 Other noninterest income 10 — 10 Total revenue from contracts with customers $ 418 $ 228 $ 646 Other noninterest income (a) $ 457 Noninterest income from other segments (b) 101 Reconciling items (c) 57 Total noninterest income $ 1,261 (a) Noninterest income considered earned outside the scope of contracts with customers. (b) Other Segments consist of corporate treasury, our principle investing unit, and various exit portfolios. (c)

Earnings Per Common Share - Bas

Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
EARNINGS
Income (loss) from continuing operations		$ 479	$ 407	$ 895	$ 732
Less: Net income (loss) attributable to noncontrolling interests		0	0	0	1
Income (loss) from continuing operations attributable to Key		479	407	895	731
Less: Dividends on Preferred Stock		15	14	29	42
Income (loss) from continuing operations attributable to Key common shareholders		464	393	866	689
Income (loss) from discontinued operations, net of taxes		3	5	5	5
Net income (loss) attributable to Key common shareholders		$ 467	$ 398	$ 871	$ 694
WEIGHTED-AVERAGE COMMON SHARES
Weighted-average common shares outstanding (in shares)		1,052,652	1,076,203	1,054,378	1,083,486
Effect of common share options and other stock awards (in shares)		13,141	16,836	14,561	15,808
Weighted-average common shares and potential common shares outstanding (in shares)	[1]	1,065,793	1,093,039	1,068,939	1,099,294
EARNINGS PER COMMON SHARE
Income (loss) from continuing operations attributable to Key common shareholders (in usd per share)		$ 0.44	$ 0.36	$ 0.82	$ 0.64
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)	[2]	0.44	0.37	0.82	0.64
Income (loss) from continuing operations attributable to Key common shareholders - assuming dilution (in usd per share)		0.44	0.36	0.81	0.63
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)	[2]	$ 0.44	$ 0.36	$ 0.81	$ 0.63
[1]	Assumes conversion of Common Share options and other stock awards and/or convertible preferred stock, as applicable.
[2]	EPS may not foot due to rounding.

Loan Portfolio - Loans by Categ

Loan Portfolio - Loans by Category (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Residential — prime loans:
Total loans	$ 88,222	$ 86,405
Commercial lease financing includes receivables held as collateral for secured borrowing	16	24
Loans	87,335	85,528
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	44,569	41,859
Commercial real estate:
Commercial mortgage	14,162	14,088
Construction	1,736	1,960
Total commercial real estate loans	15,898	16,048
Commercial lease financing	4,509	4,826
Total commercial/consumer loans	64,976	62,733
Residential — prime loans:
Total loans		62,733
Consumer Portfolio Segment [Member]
Commercial real estate:
Total commercial/consumer loans	23,246	23,672
Residential — prime loans:
Real estate — residential mortgage	5,452	5,483
Home equity loans	11,519	12,028
Total residential — prime loans	16,971	17,511
Consumer direct loans	1,785	1,794
Credit cards	1,094	1,106
Consumer indirect loans	3,396	3,261
Total loans		23,672
Commercial Credit Card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	128	119
Education Lending [Member] | Discontinued Operations [Member]
Residential — prime loans:
Loans	$ 1,200	$ 1,300

Asset Quality - Financing Recei

Asset Quality - Financing Receivable Credit Quality Indicators (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 88,222	$ 86,405
Consumer Portfolio Segment, PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	357	381
Consumer Portfolio Segment, PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	353	377
Consumer Portfolio Segment, PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	4	4
Consumer Portfolio Segment, PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Consumer Portfolio Segment, PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Consumer Portfolio Segment Excluding PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	22,889	23,291
Consumer Portfolio Segment Excluding PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	16,618	17,134
Consumer Portfolio Segment Excluding PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,781	1,790
Consumer Portfolio Segment Excluding PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,094	1,106
Consumer Portfolio Segment Excluding PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	3,396	3,261
Commercial Portfolio Segment Excluding PCI Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	64,704	62,376
Commercial Portfolio Segment Excluding PCI Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	61,987	59,785
Commercial Portfolio Segment Excluding PCI Loans [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,474	2,400
Commercial Portfolio Segment Excluding PCI Loans [Member] | Criticized (Nonaccruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	243	191
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	44,512	41,776
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	42,517	39,833
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial and Industrial [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,817	1,790
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial and Industrial [Member] | Criticized (Nonaccruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	178	153
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	13,950	13,840
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Commercial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	13,368	13,328
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Commercial [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	540	482
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Commercial [Member] | Criticized (Nonaccruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	42	30
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,733	1,934
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,682	1,894
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Construction [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	49	38
Commercial Portfolio Segment Excluding PCI Loans [Member] | RE Construction [Member] | Criticized (Nonaccruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	2	2
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,509	4,826
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial Leases [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,420	4,730
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial Leases [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	68	90
Commercial Portfolio Segment Excluding PCI Loans [Member] | Commercial Leases [Member] | Criticized (Nonaccruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	21	6
Commercial Portfolio Segment, PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	272	357
Commercial Portfolio Segment, PCI [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	168	220
Commercial Portfolio Segment, PCI [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	104	137
Commercial Portfolio Segment, PCI [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	57	83
Commercial Portfolio Segment, PCI [Member] | Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	25	41
Commercial Portfolio Segment, PCI [Member] | Commercial and Industrial [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	32	42
Commercial Portfolio Segment, PCI [Member] | RE Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	212	248
Commercial Portfolio Segment, PCI [Member] | RE Commercial [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	140	153
Commercial Portfolio Segment, PCI [Member] | RE Commercial [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	72	95
Commercial Portfolio Segment, PCI [Member] | RE Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	3	26
Commercial Portfolio Segment, PCI [Member] | RE Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	3	26
Commercial Portfolio Segment, PCI [Member] | RE Construction [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment, PCI [Member] | Commercial Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment, PCI [Member] | Commercial Leases [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment, PCI [Member] | Commercial Leases [Member] | Criticized (Accruing) [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment, PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	143	149
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment, PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	142	149
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1	0
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment Excluding PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	12,496	12,694
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	10,004	10,226
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	517	519
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	482	477
FICO Score, 750 and Above [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,493	1,472
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment, PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	103	119
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment, PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	102	117
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1	2
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment Excluding PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	7,227	7,563
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	4,871	5,181
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	673	690
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	502	508
FICO Score, 660 to 749 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,181	1,184
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment, PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	109	107
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment, PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	107	105
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	2	2
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment Excluding PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,388	2,394
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,564	1,519
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	211	225
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	110	121
FICO Score, Less than 660 [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	503	529
FICO Score, No Score [Member] | Consumer Portfolio Segment, PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	2	6
FICO Score, No Score [Member] | Consumer Portfolio Segment, PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	2	6
FICO Score, No Score [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, No Score [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, No Score [Member] | Consumer Portfolio Segment, PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, No Score [Member] | Consumer Portfolio Segment Excluding PCI [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	778	640
FICO Score, No Score [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Residential Prime Financing Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	179	208
FICO Score, No Score [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Direct Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	380	356
FICO Score, No Score [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Credit Card [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
FICO Score, No Score [Member] | Consumer Portfolio Segment Excluding PCI [Member] | Consumer Indirect Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 219	$ 76

Asset Quality - Aging Analysis

Asset Quality - Aging Analysis of Past Due and Current Loans (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 86,516	$ 84,716
Days Past Due	1,077	951
Non-performing Loans	545	503
Purchased Credit Impaired	629	738
Total loans	88,222	86,405
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	64,063	61,904
Days Past Due	641	472
Non-performing Loans	243	191
Purchased Credit Impaired	272	357
Total loans		62,733
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	22,453	22,812
Days Past Due	436	479
Non-performing Loans	302	312
Purchased Credit Impaired	357	381
Total loans		23,672
Commercial and Industrial [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	44,137	41,444
Days Past Due	375	332
Non-performing Loans	178	153
Purchased Credit Impaired	57	83
Total loans	44,569	41,859
Commercial Real Estate: Commercial Mortgage [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	13,740	13,750
Days Past Due	210	90
Non-performing Loans	42	30
Purchased Credit Impaired	212	248
Total loans	14,162	14,088
Commercial Real Estate: Construction [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,719	1,919
Days Past Due	14	15
Non-performing Loans	2	2
Purchased Credit Impaired	3	26
Total loans	1,736	1,960
Commercial Real Estate Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	15,459	15,669
Days Past Due	224	105
Non-performing Loans	44	32
Purchased Credit Impaired	215	274
Total loans	15,898	16,048
Commercial Lease Financing [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	4,467	4,791
Days Past Due	42	35
Non-performing Loans	21	6
Purchased Credit Impaired	0	0
Total loans	4,509	4,826
Commercial Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	64,976
Real Estate - Residential Mortgage [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	5,039	5,043
Days Past Due	80	85
Non-performing Loans	55	58
Purchased Credit Impaired	333	355
Total loans	5,452	5,483
Home Equity Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	11,235	11,721
Days Past Due	264	285
Non-performing Loans	222	229
Purchased Credit Impaired	20	22
Total loans	11,519	12,028
Consumer Direct Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,759	1,768
Days Past Due	22	22
Non-performing Loans	4	4
Purchased Credit Impaired	4	4
Total loans	1,785	1,794
Consumer Credit Card Financing Receivable [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	1,073	1,081
Days Past Due	21	25
Non-performing Loans	2	2
Purchased Credit Impaired	0	0
Total loans	1,094	1,106
Consumer Indirect Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,347	3,199
Days Past Due	49	62
Non-performing Loans	19	19
Purchased Credit Impaired	0	0
Total loans	3,396	3,261
Consumer Portfolio Segment [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total loans	23,246
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	256	261
30-59 Days Past Due [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	184	164
30-59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	72	97
30-59 Days Past Due [Member] | Commercial and Industrial [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	129	111
30-59 Days Past Due [Member] | Commercial Real Estate: Commercial Mortgage [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	38	26
30-59 Days Past Due [Member] | Commercial Real Estate: Construction [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	2	4
30-59 Days Past Due [Member] | Commercial Real Estate Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	40	30
30-59 Days Past Due [Member] | Commercial Lease Financing [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	15	23
30-59 Days Past Due [Member] | Real Estate - Residential Mortgage [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	11	16
30-59 Days Past Due [Member] | Home Equity Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	25	32
30-59 Days Past Due [Member] | Consumer Direct Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	8	9
30-59 Days Past Due [Member] | Consumer Credit Card Financing Receivable [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	5	7
30-59 Days Past Due [Member] | Consumer Indirect Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	23	33
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	173	98
60-89 Days Past Due [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	143	60
60-89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	30	38
60-89 Days Past Due [Member] | Commercial and Industrial [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	40	34
60-89 Days Past Due [Member] | Commercial Real Estate: Commercial Mortgage [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	100	13
60-89 Days Past Due [Member] | Commercial Real Estate: Construction [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	1	9
60-89 Days Past Due [Member] | Commercial Real Estate Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	101	22
60-89 Days Past Due [Member] | Commercial Lease Financing [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	2	4
60-89 Days Past Due [Member] | Real Estate - Residential Mortgage [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	8	7
60-89 Days Past Due [Member] | Home Equity Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	9	15
60-89 Days Past Due [Member] | Consumer Direct Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	4	4
60-89 Days Past Due [Member] | Consumer Credit Card Financing Receivable [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	4	5
60-89 Days Past Due [Member] | Consumer Indirect Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	5	7
90 and Greater Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	103	89
90 and Greater Days Past Due [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	71	57
90 and Greater Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	32	32
90 and Greater Days Past Due [Member] | Commercial and Industrial [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	28	34
90 and Greater Days Past Due [Member] | Commercial Real Estate: Commercial Mortgage [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	30	21
90 and Greater Days Past Due [Member] | Commercial Real Estate: Construction [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	9	0
90 and Greater Days Past Due [Member] | Commercial Real Estate Loans [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	39	21
90 and Greater Days Past Due [Member] | Commercial Lease Financing [Member] | Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	4	2
90 and Greater Days Past Due [Member] | Real Estate - Residential Mortgage [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	6	4
90 and Greater Days Past Due [Member] | Home Equity Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	8	9
90 and Greater Days Past Due [Member] | Consumer Direct Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	6	5
90 and Greater Days Past Due [Member] | Consumer Credit Card Financing Receivable [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	10	11
90 and Greater Days Past Due [Member] | Consumer Indirect Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Days Past Due	$ 2	$ 3

Asset Quality - Additional Info

Asset Quality - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)SecurityLoan	Jun. 30, 2017USD ($)SecurityLoan	Jun. 30, 2018USD ($)SecurityLoan	Jun. 30, 2017USD ($)SecurityLoan	Dec. 31, 2017USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (credit) for losses on lending-related commitments	$ (2)	$ 0	$ 1	$ (7)
Percentage of carrying amount of our commercial nonperforming loans outstanding	71.00%		71.00%
Percentage of nonperforming loans outstanding face value	79.00%		79.00%
Percentage of loans held for sale and other nonperforming assets	79.00%		79.00%
Net reduction to interest income	$ 7	6	$ 14	12
Financial receivable, modifications, subsequent default, recorded investment	1	2	2	2
Commitments outstanding to lend additional funds to borrowers	4		4		$ 2
Provision (credit) for loan and lease losses	66	$ 66	126	$ 139
Other Real Estate Owned Nonperforming Loan	$ 26		$ 26		31
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	0
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	55	52	96	55
Real Estate - Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial receivable, modifications, subsequent default, recorded investment			$ 146	$ 142
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized on outstanding balances	$ 3	$ 3	5	6
Continuing Operations [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (credit) for loan and lease losses	66	66	124	136
Continuing Operations [Member] | Purchase Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (credit) for loan and lease losses			1	4	3
Continuing Operations [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (credit) for loan and lease losses	44	55	82	97
Continuing Operations [Member] | Consumer Portfolio Segment [Member] | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (credit) for loan and lease losses	22	11	42	39
Continuing Operations [Member] | Consumer Portfolio Segment [Member] | Real Estate - Residential Mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision (credit) for loan and lease losses	1	$ (6)	4	$ (9)
Foreclosed Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other Real Estate Owned Nonperforming Loan	$ 23		$ 23		$ 26

Asset Quality - Breakdown of In

Asset Quality - Breakdown of Individually Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	$ 212		$ 212		$ 213
With related allowance recorded, Recorded Investment	210		210		141
Recorded Investment	422		422		354
With no related allowance recorded, Unpaid Principal Balance	266		266		246
With related allowance recorded, Unpaid Principal Balance	266		266		159
Unpaid Principal Balance	532		532		405
Specific Allowance	24		24		23
Average Recorded Investment	409	$ 428	388	$ 445
Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	143		143		138
With related allowance recorded, Recorded Investment	64		64		10
With no related allowance recorded, Unpaid Principal Balance	179		179		171
With related allowance recorded, Unpaid Principal Balance	94		94		28
Specific Allowance	7		7		6
Average Recorded Investment	194	216	177	235
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	69		69		75
With related allowance recorded, Recorded Investment	146		146		131
With no related allowance recorded, Unpaid Principal Balance	87		87		75
With related allowance recorded, Unpaid Principal Balance	172		172		131
Specific Allowance	17		17		17
Average Recorded Investment	215	212	211	210
Commercial and Industrial [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	123		123		126
With related allowance recorded, Recorded Investment	64		64		10
With no related allowance recorded, Unpaid Principal Balance	154		154		153
With related allowance recorded, Unpaid Principal Balance	94		94		28
Specific Allowance	7		7		6
Average Recorded Investment	178	201	161	225
Commercial Real Estate: Commercial Mortgage [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	20		20		12
With no related allowance recorded, Unpaid Principal Balance	25		25		18
Average Recorded Investment	16	15	16	10
Commercial Real Estate: Construction [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	0	0	0
Commercial Real Estate Loans [Member] | Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	20		20		12
With no related allowance recorded, Unpaid Principal Balance	25		25		18
Average Recorded Investment	16	15	16	10
Real Estate - Residential Mortgage [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	16		16		17
With related allowance recorded, Recorded Investment	32		32		32
With no related allowance recorded, Unpaid Principal Balance	24		24		17
With related allowance recorded, Unpaid Principal Balance	52		52		32
Specific Allowance	4		4		5
Average Recorded Investment	49	50	49	50
Home Equity Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	51		51		56
With related allowance recorded, Recorded Investment	74		74		61
With no related allowance recorded, Unpaid Principal Balance	59		59		56
With related allowance recorded, Unpaid Principal Balance	80		80		61
Specific Allowance	10		10		9
Average Recorded Investment	124	122	121	122
Consumer Indirect Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
With no related allowance recorded, Recorded Investment	2		2		2
With related allowance recorded, Recorded Investment	33		33		32
With no related allowance recorded, Unpaid Principal Balance	4		4		2
With related allowance recorded, Unpaid Principal Balance	33		33		32
Specific Allowance	3		3		3
Average Recorded Investment	35	34	34	32
Consumer Direct Loans [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
With related allowance recorded, Recorded Investment	4		4		4
With related allowance recorded, Unpaid Principal Balance	4		4		4
Specific Allowance	0		0		0
Average Recorded Investment	4	3	4	3
Credit Cards [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
With related allowance recorded, Recorded Investment	3		3		2
With related allowance recorded, Unpaid Principal Balance	3		3		2
Specific Allowance	0		0		$ 0
Average Recorded Investment	$ 3	$ 3	$ 3	$ 3

Asset Quality - Post-Modificati

Asset Quality - Post-Modification Outstanding Recorded Investment by Concession Type for Our Commercial Accruing and Nonaccruing TDRs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Modifications [Line Items]
Total commercial and consumer TDRs	$ 65	$ 63	$ 86	$ 105
Total loans	88,222		88,222		$ 86,405
Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Forgiveness of principal	5	0	5	0
Bankruptcy Plan Modification	7	29	7	29
Total	46	55	47	81
Total loans					62,733
Financing Receivable Modifications Concessions Extension Of Maturity Date	14	15	15	17
Financing Receivable Modifications Concessions Payment For Covenant Modification	20	11	20	35
Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Interest rate reduction	10	4	18	7
Forgiveness of principal	0	0	0	0
Other	9	4	21	17
Total	19	$ 8	39	$ 24
Total loans					$ 23,672
Commercial Loans [Member] | Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Total loans	64,976		64,976
Consumer Portfolio Segment [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Total loans	$ 23,246		$ 23,246

Asset Quality - Summary of Post

Asset Quality - Summary of Post-Modifcation Outstanding Recorded Investment TDRs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Financing Receivables, Modifications, Rollforward [Roll Forward]
Balance at beginning of the period	$ 317	$ 302	$ 317	$ 280
Additions	54	67	75	114
Payments	(22)	(33)	(41)	(47)
Charge-offs	(2)	(3)	(4)	(14)
Balance at end of period	$ 347	$ 333	$ 347	$ 333

Asset Quality - Breakdown of No

Asset Quality - Breakdown of Nonperforming TDRs by Loans Category (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018USD ($)SecurityLoan	Dec. 31, 2017USD ($)SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	5,706	5,184
Pre-modification Outstanding Recorded Investment	$ 434	$ 398
Post-modification Outstanding Recorded Investment	$ 347	$ 317
Nonperforming [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	2,635	2,622
Pre-modification Outstanding Recorded Investment	$ 216	$ 227
Post-modification Outstanding Recorded Investment	$ 184	$ 189
Nonperforming [Member] | Commercial Loans [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	50	28
Pre-modification Outstanding Recorded Investment	$ 119	$ 125
Post-modification Outstanding Recorded Investment	$ 95	$ 98
Nonperforming [Member] | Consumer Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	2,585	2,594
Pre-modification Outstanding Recorded Investment	$ 97	$ 102
Post-modification Outstanding Recorded Investment	$ 89	$ 91
Prior-Year Accruing [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	3,071	2,562
Pre-modification Outstanding Recorded Investment	$ 218	$ 171
Post-modification Outstanding Recorded Investment	$ 163	$ 128
Prior-Year Accruing [Member] | Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	18	4
Pre-modification Outstanding Recorded Investment	$ 54	$ 30
Post-modification Outstanding Recorded Investment	$ 37	$ 13
Prior-Year Accruing [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	0	0
Pre-modification Outstanding Recorded Investment	$ 0	$ 0
Post-modification Outstanding Recorded Investment	$ 0	$ 0
Prior-Year Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	3,053	2,558
Pre-modification Outstanding Recorded Investment	$ 164	$ 141
Post-modification Outstanding Recorded Investment	$ 126	$ 115
Commercial and Industrial [Member] | Nonperforming [Member] | Commercial Loans [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	44	20
Pre-modification Outstanding Recorded Investment	$ 106	$ 109
Post-modification Outstanding Recorded Investment	$ 86	$ 86
Commercial and Industrial [Member] | Prior-Year Accruing [Member] | Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	18	4
Pre-modification Outstanding Recorded Investment	$ 54	$ 30
Post-modification Outstanding Recorded Investment	$ 37	$ 13
Commercial and Industrial [Member] | Prior-Year Accruing [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	0	0
Pre-modification Outstanding Recorded Investment	$ 0	$ 0
Post-modification Outstanding Recorded Investment	$ 0	$ 0
Commercial Real Estate: Commercial Mortgage [Member] | Nonperforming [Member] | Commercial Real Estate Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	6	8
Pre-modification Outstanding Recorded Investment	$ 13	$ 16
Post-modification Outstanding Recorded Investment	$ 9	$ 12
Commercial Real Estate Loans [Member] | Nonperforming [Member] | Commercial Real Estate Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	6	8
Pre-modification Outstanding Recorded Investment	$ 13	$ 16
Post-modification Outstanding Recorded Investment	$ 9	$ 12
Real Estate - Residential Mortgage [Member] | Nonperforming [Member] | Consumer Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	264	308
Pre-modification Outstanding Recorded Investment	$ 18	$ 18
Post-modification Outstanding Recorded Investment	$ 17	$ 18
Real Estate - Residential Mortgage [Member] | Prior-Year Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	517	484
Pre-modification Outstanding Recorded Investment	$ 37	$ 31
Post-modification Outstanding Recorded Investment	$ 32	$ 31
Home Equity Loans [Member] | Consumer Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	1,072	1,025
Pre-modification Outstanding Recorded Investment	$ 60	$ 64
Post-modification Outstanding Recorded Investment	$ 57	$ 57
Home Equity Loans [Member] | Prior-Year Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	1,440	1,276
Pre-modification Outstanding Recorded Investment	$ 85	$ 75
Post-modification Outstanding Recorded Investment	$ 68	$ 59
Consumer Direct Loans [Member] | Nonperforming [Member] | Consumer Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	119	114
Pre-modification Outstanding Recorded Investment	$ 2	$ 2
Post-modification Outstanding Recorded Investment	$ 2	$ 2
Consumer Direct Loans [Member] | Prior-Year Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	82	48
Pre-modification Outstanding Recorded Investment	$ 4	$ 3
Post-modification Outstanding Recorded Investment	$ 3	$ 2
Consumer Credit Card [Member] | Nonperforming [Member] | Consumer Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	252	322
Pre-modification Outstanding Recorded Investment	$ 1	$ 2
Post-modification Outstanding Recorded Investment	$ 1	$ 1
Consumer Credit Card [Member] | Prior-Year Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	513	430
Pre-modification Outstanding Recorded Investment	$ 3	$ 1
Post-modification Outstanding Recorded Investment	$ 1	$ 1
Consumer Indirect Loans [Member] | Consumer Portfolio Segment [Member] | Nonperforming [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	878	825
Pre-modification Outstanding Recorded Investment	$ 16	$ 16
Post-modification Outstanding Recorded Investment	$ 12	$ 13
Consumer Indirect Loans [Member] | Prior-Year Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans | SecurityLoan	501	320
Pre-modification Outstanding Recorded Investment	$ 35	$ 31
Post-modification Outstanding Recorded Investment	$ 22	$ 22

Asset Quality - Changes in Allo

Asset Quality - Changes in Allowance for Loan and Lease Losses by Loan Category (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 897	$ 893	$ 893	$ 882	$ 882
Provision	66	66	126	139
Charge-offs	(82)	(86)	(158)	(169)
Recoveries	20	18	40	39
Ending balance	901	891	901	891	893
Provision (credit) for losses on lending-related commitments	(2)	0	1	(7)
Continuing Operations [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	881	870	877	858	858
Provision	66	66	124	136
Charge-offs	(79)	(82)	(151)	(159)
Recoveries	19	16	37	35
Ending balance	887	870	887	870	877
Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	742	727	735	716	716
Provision	44	55	82	97
Charge-offs	(45)	(44)	(84)	(83)
Recoveries	8	2	16	10
Ending balance	749	740	749	740	735
Continuing Operations [Member] | Commercial and Industrial [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	533	512	529	508	508
Provision	41	54	76	85
Charge-offs	(39)	(40)	(76)	(72)
Recoveries	7	2	13	7
Ending balance	542	528	542	528	529
Continuing Operations [Member] | Commercial Real Estate: Commercial Mortgage [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	136	146	133	144	144
Provision	4	1	8	3
Charge-offs	(2)	(3)	(3)	(3)
Recoveries	1	0	1	0
Ending balance	139	144	139	144	133
Continuing Operations [Member] | RE Construction [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	33	29	30	22	22
Provision	(5)	(1)	(3)	5
Charge-offs	0	0	0	0
Recoveries	0	0	1	1
Ending balance	28	28	28	28	30
Continuing Operations [Member] | Commercial Real Estate [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	169	175	163	166	166
Provision	(1)	0	5	8
Charge-offs	(2)	(3)	(3)	(3)
Recoveries	1	0	2	1
Ending balance	167	172	167	172	163
Continuing Operations [Member] | Commercial Lease Financing [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	40	40	43	42	42
Provision	4	1	1	4
Charge-offs	(4)	(1)	(5)	(8)
Recoveries	0	0	1	2
Ending balance	40	40	40	40	43
Continuing Operations [Member] | Real Estate - Residential Mortgage [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	9	18	7	17	17
Provision	1	(6)	4	(9)
Charge-offs	0	(4)	(1)	(2)
Recoveries	0	1	0	3
Ending balance	10	9	10	9	7
Continuing Operations [Member] | Home Equity Loans [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	38	53	43	54	54
Provision	2	(7)	(2)	(3)
Charge-offs	(6)	(9)	(10)	(17)
Recoveries	3	5	6	8
Ending balance	37	42	37	42	43
Continuing Operations [Member] | Consumer Direct Loans [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	27	24	28	24	24
Provision	6	7	11	16
Charge-offs	(9)	(8)	(17)	(18)
Recoveries	2	2	4	3
Ending balance	26	25	26	25	28
Continuing Operations [Member] | Credit Cards [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	45	38	44	38	38
Provision	11	16	23	26
Charge-offs	(12)	(12)	(24)	(23)
Recoveries	2	2	3	3
Ending balance	46	44	46	44	44
Continuing Operations [Member] | Consumer Indirect Loans [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	20	10	20	9	9
Provision	2	1	6	9
Charge-offs	(7)	(5)	(15)	(16)
Recoveries	4	4	8	8
Ending balance	19	10	19	10	20
Continuing Operations [Member] | Consumer Loans [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	139	143	142	142	142
Provision	22	11	42	39
Charge-offs	(34)	(38)	(67)	(76)
Recoveries	11	14	21	25
Ending balance	138	130	138	130	142
Discontinued Operations [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	16	23	16	24	24
Provision	0	0	2	3
Charge-offs	(3)	(4)	(7)	(10)
Recoveries	1	2	3	4
Ending balance	$ 14	$ 21	$ 14	$ 21	$ 16

Asset Quality - Breakdown of Al

Asset Quality - Breakdown of Allowance for Loan and Lease Losses and Corresponding Loan Balances (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance, Total ALLL - Including Discontinued Operations	$ 27	$ 26
Collectively Evaluated for Impairment, Allowance, Total ALLL - Including Discontinued Operations	867	861
Purchased Credit Impaired, Allowance, Total ALLL - Including Discontinued Operations	7	6
Loans, Outstanding, Total ALLL - Including Discontinued Operations	89,416	87,719
Individually Evaluated for Impairment, Outstanding, Total ALLL - Including Discontinued Operations	443	375
Collectively Evaluated for Impairment, Outstanding, Total ALLL - Including Discontinued Operations	88,344	86,606
Purchased Credit Impaired, Outstanding, Total ALLL - Including Discontinued Operations	629	738
Continuing Operations [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	24	23
Collectively Evaluated for Impairment, Allowance	856	848
Purchase Credit Impairment, Allowance	7	6
Total loans	88,222	86,405
Individually Evaluated for Impairment, Outstanding	422	354
Collectively Evaluated for Impairment, Outstanding	87,171	85,313
Purchase Credit Impairment, Outstanding	629	738
Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	7	6
Collectively Evaluated for Impairment, Allowance	737	724
Purchase Credit Impairment, Allowance	5	5
Total loans		62,733
Individually Evaluated for Impairment, Outstanding	207	148
Collectively Evaluated for Impairment, Outstanding	64,497	62,228
Purchase Credit Impairment, Outstanding	272	357
Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	17	17
Collectively Evaluated for Impairment, Allowance	119	124
Purchase Credit Impairment, Allowance	2	1
Total loans		23,672
Individually Evaluated for Impairment, Outstanding	215	206
Collectively Evaluated for Impairment, Outstanding	22,674	23,085
Purchase Credit Impairment, Outstanding	357	381
Discontinued Operations [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	3	3
Collectively Evaluated for Impairment, Allowance	11	13
Purchase Credit Impairment, Allowance	0	0
Total loans	1,194	1,314
Individually Evaluated for Impairment, Outstanding	21	21
Collectively Evaluated for Impairment, Outstanding	1,173	1,293
Purchase Credit Impairment, Outstanding	0	0
Commercial and Industrial [Member] | Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	7	6
Collectively Evaluated for Impairment, Allowance	533	520
Purchase Credit Impairment, Allowance	2	3
Total loans	44,569	41,859
Individually Evaluated for Impairment, Outstanding	187	136
Collectively Evaluated for Impairment, Outstanding	44,325	41,640
Purchase Credit Impairment, Outstanding	57	83
Commercial Real Estate: Commercial Mortgage [Member] | Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	136	131
Purchase Credit Impairment, Allowance	3	2
Total loans	14,162	14,088
Individually Evaluated for Impairment, Outstanding	20	12
Collectively Evaluated for Impairment, Outstanding	13,930	13,828
Purchase Credit Impairment, Outstanding	212	248
Commercial Real Estate: Construction [Member] | Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	28	30
Purchase Credit Impairment, Allowance	0	0
Total loans	1,736	1,960
Individually Evaluated for Impairment, Outstanding	0	0
Collectively Evaluated for Impairment, Outstanding	1,733	1,934
Purchase Credit Impairment, Outstanding	3	26
Commercial Real Estate Loans [Member] | Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	164	161
Purchase Credit Impairment, Allowance	3	2
Total loans	15,898	16,048
Individually Evaluated for Impairment, Outstanding	20	12
Collectively Evaluated for Impairment, Outstanding	15,663	15,762
Purchase Credit Impairment, Outstanding	215	274
Commercial Lease Financing [Member] | Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	40	43
Purchase Credit Impairment, Allowance	0	0
Total loans	4,509	4,826
Individually Evaluated for Impairment, Outstanding	0	0
Collectively Evaluated for Impairment, Outstanding	4,509	4,826
Purchase Credit Impairment, Outstanding	0	0
Commercial Loans [Member] | Continuing Operations [Member] | Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	64,976
Real Estate - Residential Mortgage [Member] | Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	4	5
Collectively Evaluated for Impairment, Allowance	5	2
Purchase Credit Impairment, Allowance	1	0
Total loans	5,452	5,483
Individually Evaluated for Impairment, Outstanding	48	49
Collectively Evaluated for Impairment, Outstanding	5,071	5,079
Purchase Credit Impairment, Outstanding	333	355
Home Equity Loans [Member] | Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	10	9
Collectively Evaluated for Impairment, Allowance	26	33
Purchase Credit Impairment, Allowance	1	1
Total loans	11,519	12,028
Individually Evaluated for Impairment, Outstanding	125	117
Collectively Evaluated for Impairment, Outstanding	11,374	11,889
Purchase Credit Impairment, Outstanding	20	22
Consumer Direct Loans [Member] | Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	26	28
Purchase Credit Impairment, Allowance	0	0
Total loans	1,785	1,794
Individually Evaluated for Impairment, Outstanding	4	4
Collectively Evaluated for Impairment, Outstanding	1,777	1,786
Purchase Credit Impairment, Outstanding	4	4
Consumer Credit Card Financing Receivable [Member] | Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	0	0
Collectively Evaluated for Impairment, Allowance	46	44
Purchase Credit Impairment, Allowance	0	0
Total loans	1,094	1,106
Individually Evaluated for Impairment, Outstanding	3	2
Collectively Evaluated for Impairment, Outstanding	1,091	1,104
Purchase Credit Impairment, Outstanding	0	0
Consumer Indirect Loans [Member] | Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually Evaluated for Impairment, Allowance	3	3
Collectively Evaluated for Impairment, Allowance	16	17
Purchase Credit Impairment, Allowance	0	0
Total loans	3,396	3,261
Individually Evaluated for Impairment, Outstanding	35	34
Collectively Evaluated for Impairment, Outstanding	3,361	3,227
Purchase Credit Impairment, Outstanding	0	0
Consumer Loans [Member] | Continuing Operations [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	23,246
Education Lending [Member] | Discontinued Operations [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans at fair value	$ 2	$ 2

Asset Quality - Changes in Liab

Asset Quality - Changes in Liability for Credit Losses on Lending Related Commitments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 60	$ 48	$ 57	$ 55
Provision (credit) for losses on lending-related commitments	(2)	0	1	(7)
Balance at end of period	$ 58	$ 48	$ 58	$ 48

Asset Quality - Changes in Outs

Asset Quality - Changes in Outstanding Unpaid Principal Balance, Carrying Amount, and Accretable Yield for PCI Loans (Details) - PCI Loans [Member] - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2018	Dec. 31, 2016
Accretable Yield
Balance at beginning of period	$ 132	$ 131	$ 197
Additions	0	0	(32)
Accretion	(11)	(23)	(44)
Net reclassifications from nonaccretable to accretable	6	28	15
Payments received, net	6	(15)	(4)
Disposals	0	0	(1)
Balance at end of period	121	121	131
Carrying Amount	622	622	738	$ 812	$ 865
Outstanding Unpaid Principal Balance	$ 669	$ 669	$ 803	$ 930	$ 1,002

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	$ 833,000,000	$ 836,000,000
Securities available for sale	17,367,000,000	18,139,000,000
Loans, net of unearned income	88,222,000,000	86,405,000,000
Loans held for sale	0	0
Derivative assets, netting adjustments	(219,000,000)	(443,000,000)
Total derivative assets	738,000,000	669,000,000
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, netting adjustments	(598,000,000)	(616,000,000)
US Treasury and Government [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	146,000,000	157,000,000
US States and Political Subdivisions Debt Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	7,000,000	9,000,000
Other Debt Obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	20,000,000	20,000,000
Residential Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1,367,000,000	1,439,000,000
Other Mortgage-Backed Securities [Member] | Commercial Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1,933,000,000	1,854,000,000
Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	817,000,000	821,000,000
Commercial loans	16,000,000	15,000,000
Total trading account assets	833,000,000	836,000,000
Securities available for sale	17,367,000,000	18,139,000,000
Total other investments	130,000,000	144,000,000
Loans, net of unearned income	3,000,000	2,000,000
Loans held for sale	58,000,000	71,000,000
Derivative assets, gross	957,000,000	1,112,000,000
Derivative assets, netting adjustments	(219,000,000)	(443,000,000)
Total derivative assets	738,000,000	669,000,000
Accrued income and other assets	0	0
Total assets at fair value	19,129,000,000	19,861,000,000
LIABILITIES MEASURED ON A RECURRING BASIS
Accrued expense and other liabilities	0	0
Total liabilities on a recurring basis at fair value	1,065,000,000	925,000,000
Recurring [Member] | US Treasury and Government [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	537,000,000	615,000,000
Securities available for sale	146,000,000	157,000,000
Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	36,000,000	37,000,000
Securities available for sale	7,000,000	9,000,000
Recurring [Member] | Other Debt Obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	107,000,000	65,000,000
Securities available for sale	20,000,000	20,000,000
Recurring [Member] | Commercial Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1,933,000,000	1,854,000,000
Recurring [Member] | Principal Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	13,000,000	13,000,000
Recurring [Member] | Principal Investments Indirect [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	109,000,000	124,000,000
Recurring [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	122,000,000	137,000,000
Recurring [Member] | Equity Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	7,000,000	7,000,000
Recurring [Member] | Equity Investments Direct, NAV [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	1,000,000	0
Recurring [Member] | Equity Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	8,000,000	7,000,000
Recurring [Member] | Other Mortgage-Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	137,000,000	104,000,000
Recurring [Member] | Other Mortgage-Backed Securities [Member] | Residential Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1,367,000,000	1,439,000,000
Recurring [Member] | Short [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	639,000,000	634,000,000
Recurring [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	1,024,000,000	907,000,000
Derivative liabilities, netting adjustments	(598,000,000)	(616,000,000)
Total derivative liabilities	426,000,000	291,000,000
Recurring [Member] | Interest Rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	343,000,000	722,000,000
Recurring [Member] | Interest Rate [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	423,000,000	520,000,000
Recurring [Member] | Foreign Exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	116,000,000	130,000,000
Recurring [Member] | Foreign Exchange [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	103,000,000	124,000,000
Recurring [Member] | Commodity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	494,000,000	255,000,000
Recurring [Member] | Commodity [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	484,000,000	246,000,000
Recurring [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	1,000,000
Recurring [Member] | Credit [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	12,000,000	4,000,000
Recurring [Member] | Other [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	4,000,000	4,000,000
Recurring [Member] | Other [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	2,000,000	13,000,000
Level 1 [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Commercial loans	0	0
Total trading account assets	0	0
Securities available for sale	0	0
Total other investments	0	0
Loans, net of unearned income	0	0
Loans held for sale	0	0
Derivative assets, gross	84,000,000	100,000,000
Derivative assets, netting adjustments	0	0
Total derivative assets	84,000,000	100,000,000
Accrued income and other assets	0	0
Total assets at fair value	84,000,000	100,000,000
LIABILITIES MEASURED ON A RECURRING BASIS
Accrued expense and other liabilities	0	0
Total liabilities on a recurring basis at fair value	79,000,000	170,000,000
Level 1 [Member] | Recurring [Member] | US Treasury and Government [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 [Member] | Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 [Member] | Recurring [Member] | Other Debt Obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 1 [Member] | Recurring [Member] | Commercial Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 [Member] | Recurring [Member] | Principal Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 [Member] | Recurring [Member] | Principal Investments Indirect [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 [Member] | Recurring [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 [Member] | Recurring [Member] | Equity Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 [Member] | Recurring [Member] | Equity Investments Direct, NAV [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 [Member] | Recurring [Member] | Equity Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 1 [Member] | Recurring [Member] | Other Mortgage-Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Level 1 [Member] | Recurring [Member] | Other Mortgage-Backed Securities [Member] | Residential Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 1 [Member] | Recurring [Member] | Short [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	6,000,000	72,000,000
Level 1 [Member] | Recurring [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	73,000,000	98,000,000
Derivative liabilities, netting adjustments	0	0
Total derivative liabilities	73,000,000	98,000,000
Level 1 [Member] | Recurring [Member] | Interest Rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 [Member] | Recurring [Member] | Interest Rate [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 1 [Member] | Recurring [Member] | Foreign Exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	84,000,000	100,000,000
Level 1 [Member] | Recurring [Member] | Foreign Exchange [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	73,000,000	98,000,000
Level 1 [Member] | Recurring [Member] | Commodity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 [Member] | Recurring [Member] | Commodity [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 1 [Member] | Recurring [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 [Member] | Recurring [Member] | Credit [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 1 [Member] | Recurring [Member] | Other [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 1 [Member] | Recurring [Member] | Other [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 2 [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	817,000,000	821,000,000
Commercial loans	16,000,000	15,000,000
Total trading account assets	833,000,000	836,000,000
Securities available for sale	17,347,000,000	18,119,000,000
Total other investments	0	4,000,000
Loans, net of unearned income	0	0
Loans held for sale	58,000,000	70,000,000
Derivative assets, gross	865,000,000	999,000,000
Derivative assets, netting adjustments	0	0
Total derivative assets	865,000,000	999,000,000
Accrued income and other assets	0	0
Total assets at fair value	19,103,000,000	20,028,000,000
LIABILITIES MEASURED ON A RECURRING BASIS
Accrued expense and other liabilities	0	0
Total liabilities on a recurring basis at fair value	1,575,000,000	1,371,000,000
Level 2 [Member] | Recurring [Member] | US Treasury and Government [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	537,000,000	615,000,000
Securities available for sale	146,000,000	157,000,000
Level 2 [Member] | Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	36,000,000	37,000,000
Securities available for sale	7,000,000	9,000,000
Level 2 [Member] | Recurring [Member] | Other Debt Obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	107,000,000	65,000,000
Securities available for sale	0	0
Level 2 [Member] | Recurring [Member] | Commercial Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1,933,000,000	1,854,000,000
Level 2 [Member] | Recurring [Member] | Principal Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 [Member] | Recurring [Member] | Principal Investments Indirect [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 [Member] | Recurring [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 [Member] | Recurring [Member] | Equity Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	4,000,000
Level 2 [Member] | Recurring [Member] | Equity Investments Direct, NAV [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 2 [Member] | Recurring [Member] | Equity Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	4,000,000
Level 2 [Member] | Recurring [Member] | Other Mortgage-Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	137,000,000	104,000,000
Level 2 [Member] | Recurring [Member] | Other Mortgage-Backed Securities [Member] | Residential Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	1,367,000,000	1,439,000,000
Level 2 [Member] | Recurring [Member] | Short [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	633,000,000	562,000,000
Level 2 [Member] | Recurring [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	942,000,000	809,000,000
Derivative liabilities, netting adjustments	0	0
Total derivative liabilities	942,000,000	809,000,000
Level 2 [Member] | Recurring [Member] | Interest Rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	338,000,000	713,000,000
Level 2 [Member] | Recurring [Member] | Interest Rate [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	423,000,000	520,000,000
Level 2 [Member] | Recurring [Member] | Foreign Exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	32,000,000	30,000,000
Level 2 [Member] | Recurring [Member] | Foreign Exchange [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	30,000,000	26,000,000
Level 2 [Member] | Recurring [Member] | Commodity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	494,000,000	255,000,000
Level 2 [Member] | Recurring [Member] | Commodity [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	484,000,000	246,000,000
Level 2 [Member] | Recurring [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 2 [Member] | Recurring [Member] | Credit [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	3,000,000	4,000,000
Level 2 [Member] | Recurring [Member] | Other [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	1,000,000	1,000,000
Level 2 [Member] | Recurring [Member] | Other [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	2,000,000	13,000,000
Level 3 [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Commercial loans	0	0
Total trading account assets	0	0
Securities available for sale	20,000,000	20,000,000
Total other investments	20,000,000	16,000,000
Loans, net of unearned income	3,000,000	2,000,000
Loans held for sale	0	1,000,000
Derivative assets, gross	8,000,000	13,000,000
Derivative assets, netting adjustments	0	0
Total derivative assets	8,000,000	13,000,000
Accrued income and other assets	0	0
Total assets at fair value	51,000,000	52,000,000
LIABILITIES MEASURED ON A RECURRING BASIS
Accrued expense and other liabilities	0	0
Total liabilities on a recurring basis at fair value	9,000,000	0
Level 3 [Member] | Recurring [Member] | US Treasury and Government [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 3 [Member] | Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	0	0
Level 3 [Member] | Recurring [Member] | Other Debt Obligations [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Securities available for sale	20,000,000	20,000,000
Level 3 [Member] | Recurring [Member] | Commercial Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 [Member] | Recurring [Member] | Principal Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	13,000,000	13,000,000
Level 3 [Member] | Recurring [Member] | Principal Investments Indirect [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 3 [Member] | Recurring [Member] | Principal Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	13,000,000	13,000,000
Level 3 [Member] | Recurring [Member] | Equity Investments Direct [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	7,000,000	3,000,000
Level 3 [Member] | Recurring [Member] | Equity Investments Direct, NAV [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	0	0
Level 3 [Member] | Recurring [Member] | Equity Investments [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total other investments	7,000,000	3,000,000
Level 3 [Member] | Recurring [Member] | Other Mortgage-Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Total trading account securities	0	0
Level 3 [Member] | Recurring [Member] | Other Mortgage-Backed Securities [Member] | Residential Mortgage Backed Securities [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Level 3 [Member] | Recurring [Member] | Short [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Short positions	0	0
Level 3 [Member] | Recurring [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	9,000,000	0
Derivative liabilities, netting adjustments	0	0
Total derivative liabilities	9,000,000	0
Level 3 [Member] | Recurring [Member] | Interest Rate [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	5,000,000	9,000,000
Level 3 [Member] | Recurring [Member] | Interest Rate [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 3 [Member] | Recurring [Member] | Foreign Exchange [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 3 [Member] | Recurring [Member] | Foreign Exchange [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 3 [Member] | Recurring [Member] | Commodity [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	0
Level 3 [Member] | Recurring [Member] | Commodity [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Level 3 [Member] | Recurring [Member] | Credit [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	0	1,000,000
Level 3 [Member] | Recurring [Member] | Credit [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	9,000,000	0
Level 3 [Member] | Recurring [Member] | Other [Member]
ASSETS MEASURED ON A RECURRING BASIS
Derivative assets, gross	3,000,000	3,000,000
Level 3 [Member] | Recurring [Member] | Other [Member] | Long [Member]
LIABILITIES MEASURED ON A RECURRING BASIS
Derivative liabilities, gross	0	0
Collateralized Mortgage Obligations [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	13,894,000,000	14,660,000,000
Collateralized Mortgage Obligations [Member] | Level 1 [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	0	0
Collateralized Mortgage Obligations [Member] | Level 2 [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	13,894,000,000	14,660,000,000
Collateralized Mortgage Obligations [Member] | Level 3 [Member] | Recurring [Member]
ASSETS MEASURED ON A RECURRING BASIS
Securities available for sale	$ 0	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale adjusted to fair value	$ 0	$ 0
Other equity investments	93,000,000
Loans, net of allowance	87,335,000,000	85,528,000,000
Discontinued Operations [Member] | Education Lending [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of allowance	1,200,000,000	1,300,000,000
Loans at fair value	2,000,000	2,000,000
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale adjusted to fair value	58,000,000	71,000,000
Loans, net of allowance	84,969,000,000	84,003,000,000
Loans at fair value	3,000,000	2,000,000
Fair Value [Member] | Discontinued Operations [Member] | Education Lending [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of allowance	1,000,000,000	1,100,000,000
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale adjusted to fair value	58,000,000	71,000,000
Loans, net of allowance	87,332,000,000	85,526,000,000
Loans at fair value	3,000,000	2,000,000
Carrying Amount [Member] | Discontinued Operations [Member] | Education Lending [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of allowance	1,200,000,000	1,300,000,000
Level 3 [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale adjusted to fair value	0	1,000,000
Loans, net of allowance	84,969,000,000	84,003,000,000
Loans at fair value	3,000,000	2,000,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities measured at fair value on non recurring basis	$ 0	$ 0

Fair Value Measurements - Fai62

Fair Value Measurements - Fair Value of Direct and Indirect Investments, Related Unfunded Commitments and Financial Support Provided (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Minimum [Member] | Indirect Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period of funds			1 year
Maximum [Member] | Indirect Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period of funds			6 years
Principal Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	$ 122		$ 122
Unfunded Commitments	28		28
Funded Commitments	0	$ 0	1	$ 1
Funded Other	0	0	0	0
Principal Investments [Member] | Direct Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	13		13
Unfunded Commitments	0		0
Funded Commitments	0	0	0	0
Funded Other	0	0	0	0
Principal Investments [Member] | Indirect Investments [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair Value	109		109
Unfunded Commitments	28		28
Funded Commitments	0	0	1	1
Funded Other	$ 0	$ 0	$ 0	$ 0

Fair Value Measurements - Chang

Fair Value Measurements - Change in Fair Values of Level 3 Financial Instruments (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Securities Available for Sale [Member] | Other Debt Obligations [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	$ 20,000,000	$ 17,000,000	$ 20,000,000	$ 17,000,000
Gains (Losses) Included in Other Comprehensive Income	0	3,000,000	0	3,000,000
Gains (Losses) Included in Earnings	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	20,000,000	20,000,000	20,000,000	20,000,000
Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Other Investments [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	7,000,000		3,000,000
Gains (Losses) Included in Other Comprehensive Income	0		0
Gains (Losses) Included in Earnings	0		0
Purchases	0		0
Sales	0		0
Settlements	0		0
Transfers Other	0		0
Transfers into Level 3	0		4,000,000
Transfers out of Level 3	0		0
Ending Balance	7,000,000		7,000,000
Unrealized Gains (Losses) Included in Earnings	0		0
Other Investments [Member] | Principal Investments Direct [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	12,000,000	21,000,000	13,000,000	27,000,000
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	1,000,000	(3,000,000)	0	(5,000,000)
Purchases	1,000,000	0	1,000,000	0
Sales	(1,000,000)	(3,000,000)	(1,000,000)	(7,000,000)
Settlements	0	0	0	0
Transfers Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	13,000,000	15,000,000	13,000,000	15,000,000
Unrealized Gains (Losses) Included in Earnings	2,000,000	3,000,000	1,000,000	(3,000,000)
Interest Rate [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	4,000,000	5,000,000	9,000,000	7,000,000
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	(1,000,000)	0	(2,000,000)	0
Purchases	0	0	1,000,000	0
Sales	(2,000,000)	0	(2,000,000)	0
Settlements	0	0	0	0
Transfers Other	0	0	0	0
Transfers into Level 3	4,000,000	11,000,000	4,000,000	12,000,000
Transfers out of Level 3	0	0	(5,000,000)	(3,000,000)
Ending Balance	5,000,000	16,000,000	5,000,000	16,000,000
Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Credit [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	0	1,000,000	1,000,000	1,000,000
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	(15,000,000)	(4,000,000)	(20,000,000)	(7,000,000)
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	6,000,000	4,000,000	10,000,000	7,000,000
Transfers Other	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	(9,000,000)	1,000,000	(9,000,000)	1,000,000
Unrealized Gains (Losses) Included in Earnings	0	0	0	0
Other [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	3,000,000	4,000,000	3,000,000	2,000,000
Gains (Losses) Included in Other Comprehensive Income	0	0	0	0
Gains (Losses) Included in Earnings	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	0	0	0	0
Transfers Other	0	0	0	2,000,000
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Ending Balance	3,000,000	4,000,000	3,000,000	4,000,000
Unrealized Gains (Losses) Included in Earnings	0	$ 0	0	$ 0
Loans Held For Sale Fair Value [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	1,000,000		1,000,000
Gains (Losses) Included in Other Comprehensive Income	0		0
Gains (Losses) Included in Earnings	0		0
Purchases	0		0
Sales	(1,000,000)		(1,000,000)
Settlements	0		0
Transfers Other	0		0
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Ending Balance	0		0
Unrealized Gains (Losses) Included in Earnings	0		0
Loans Held For Investment Fair Value [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning Balance	2,000,000		2,000,000
Gains (Losses) Included in Other Comprehensive Income	0		0
Gains (Losses) Included in Earnings	0		0
Purchases	0		0
Sales	0		0
Settlements	0		0
Transfers Other	1,000,000		1,000,000
Transfers into Level 3	0		0
Transfers out of Level 3	0		0
Ending Balance	3,000,000		3,000,000
Unrealized Gains (Losses) Included in Earnings	$ 0		$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Nonrecurring Basis (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Jun. 30, 2018
ASSETS MEASURED ON A NONRECURRING BASIS
Tax credit carryforward, provisional impairment charges	$ 31
Fair Value, Measurements, Nonrecurring [Member]
ASSETS MEASURED ON A NONRECURRING BASIS
Impaired loans and leases	9	$ 74
Accrued income and other assets	138	2
Total assets at fair value	147	76
Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
ASSETS MEASURED ON A NONRECURRING BASIS
Impaired loans and leases	0	0
Accrued income and other assets	0	0
Total assets at fair value	0	0
Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
ASSETS MEASURED ON A NONRECURRING BASIS
Impaired loans and leases	0	3
Accrued income and other assets	5	0
Total assets at fair value	5	3
Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
ASSETS MEASURED ON A NONRECURRING BASIS
Impaired loans and leases	9	71
Accrued income and other assets	133	2
Total assets at fair value	142	$ 73
LIHTC And Historic Tax Credit Investments [Member]
ASSETS MEASURED ON A NONRECURRING BASIS
Tax credit carryforward, amount	$ 119

Fair Value Measurements - Quant

Fair Value Measurements - Quantitative Information about Level 3 Fair Value Measurements (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Other investments	$ 709	$ 726
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans and leases	74	9
Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans and leases	71	9
Level 3 [Member] | Other Investments [Member] | Recurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Other investments	$ 13	$ 13
Level 3 [Member] | EBITDA Multiple [Member] | Recurring [Member] | Weighted Average [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Percentage of significant unobservable inputs	6.00%	6.00%
Level 3 [Member] | EBITDA Multiple (Where Applicable) [Member] | Recurring [Member] | Weighted Average [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Percentage of significant unobservable inputs		6.00%
Measurement Input, Discount Rate [Member] | Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Minimum [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Percentage of significant unobservable inputs		0.00%
Measurement Input, Discount Rate [Member] | Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Maximum [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Percentage of significant unobservable inputs		50.00%
Measurement Input, Discount Rate [Member] | Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Weighted Average [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Percentage of significant unobservable inputs		23.00%

Fair Value Measurements - Fai66

Fair Value Measurements - Fair Value Disclosures of Financial Instruments (Detail) - USD ($)		Jun. 30, 2018	Dec. 31, 2017
ASSETS
Trading account assets		$ 833,000,000	$ 836,000,000
Loans held for sale		0	0
Derivative assets		738,000,000	669,000,000
Securities available for sale		17,367,000,000	18,139,000,000
Amortized Cost		12,277,000,000	11,830,000,000
Held-to-maturity securities		11,735,000,000	11,565,000,000
Loans, net of allowance		87,335,000,000	85,528,000,000
Loans held for sale	[1]	1,418,000,000	1,107,000,000
LIABILITIES
Long-term debt		13,853,000,000	14,333,000,000
Carrying Amount [Member]
ASSETS
Trading account assets		833,000,000	836,000,000
Other investments		709,000,000	726,000,000
Loans, net of allowance		3,000,000	2,000,000
Loans held for sale		58,000,000	71,000,000
Securities available for sale		17,367,000,000	18,139,000,000
Amortized Cost		12,277,000,000	11,830,000,000
Loans, net of allowance		87,332,000,000	85,526,000,000
Loans held for sale		1,360,000,000	1,036,000,000
Cash and short-term investments		3,430,000,000	5,118,000,000
LIABILITIES
Time deposits		12,490,000,000	11,647,000,000
Short-term borrowings		2,306,000,000	1,011,000,000
Long-term debt		13,853,000,000	14,333,000,000
Deposits with no stated maturity		92,058,000,000	93,588,000,000
Fair Value [Member]
ASSETS
Trading account assets		833,000,000	836,000,000
Other investments		709,000,000	726,000,000
Loans, net of allowance		3,000,000	2,000,000
Loans held for sale		58,000,000	71,000,000
Securities available for sale		17,367,000,000	18,139,000,000
Held-to-maturity securities		11,735,000,000	11,565,000,000
Loans, net of allowance		84,969,000,000	84,003,000,000
Loans held for sale		1,360,000,000	1,036,000,000
Cash and short-term investments		3,430,000,000	5,118,000,000
LIABILITIES
Time deposits		12,557,000,000	11,750,000,000
Short-term borrowings		2,306,000,000	1,011,000,000
Long-term debt		13,881,000,000	14,626,000,000
Deposits with no stated maturity		92,058,000,000	93,588,000,000
Fair Value [Member] | Level 1 [Member]
ASSETS
Trading account assets		0	0
Other investments		0	0
Loans, net of allowance		0	0
Loans held for sale		0	0
Securities available for sale		0	0
Held-to-maturity securities		0	0
Loans, net of allowance		0	0
Loans held for sale		0	0
Cash and short-term investments		3,430,000,000	5,118,000,000
LIABILITIES
Time deposits		0	0
Short-term borrowings		6,000,000	72,000,000
Long-term debt		12,708,000,000	13,407,000,000
Deposits with no stated maturity		0	0
Fair Value [Member] | Level 2 [Member]
ASSETS
Trading account assets		833,000,000	836,000,000
Other investments		0	4,000,000
Loans, net of allowance		0	0
Loans held for sale		58,000,000	70,000,000
Securities available for sale		17,347,000,000	18,119,000,000
Held-to-maturity securities		11,735,000,000	11,565,000,000
Loans, net of allowance		0	0
Loans held for sale		0	0
Cash and short-term investments		0	0
LIABILITIES
Time deposits		12,557,000,000	11,750,000,000
Short-term borrowings		2,300,000,000	939,000,000
Long-term debt		1,173,000,000	1,219,000,000
Deposits with no stated maturity		92,058,000,000	93,588,000,000
Fair Value [Member] | Level 3 [Member]
ASSETS
Trading account assets		0	0
Other investments		599,000,000	598,000,000
Loans, net of allowance		3,000,000	2,000,000
Loans held for sale		0	1,000,000
Securities available for sale		20,000,000	20,000,000
Held-to-maturity securities		0	0
Loans, net of allowance		84,969,000,000	84,003,000,000
Loans held for sale		1,360,000,000	1,036,000,000
Cash and short-term investments		0	0
LIABILITIES
Time deposits		0	0
Short-term borrowings		0	0
Long-term debt		0	0
Deposits with no stated maturity		0	0
Fair Value [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
ASSETS
Other investments		110,000,000	124,000,000
Derivatives Designated as Hedging Instruments [Member] | Carrying Amount [Member]
ASSETS
Derivative assets		48,000,000	(12,000,000)
LIABILITIES
Derivative liabilities		0	2,000,000
Derivatives Designated as Hedging Instruments [Member] | Fair Value [Member]
ASSETS
Derivative assets		48,000,000	(12,000,000)
Derivative assets, Netting Adjustment		8,000,000	(94,000,000)
LIABILITIES
Derivative liabilities		0	2,000,000
Derivative liabilities, Netting Adjustment		(1,000,000)	(48,000,000)
Derivatives Designated as Hedging Instruments [Member] | Fair Value [Member] | Level 1 [Member]
ASSETS
Derivative assets		3,000,000	1,000,000
LIABILITIES
Derivative liabilities		0	4,000,000
Derivatives Designated as Hedging Instruments [Member] | Fair Value [Member] | Level 2 [Member]
ASSETS
Derivative assets		37,000,000	81,000,000
LIABILITIES
Derivative liabilities		1,000,000	46,000,000
Derivatives Designated as Hedging Instruments [Member] | Fair Value [Member] | Level 3 [Member]
ASSETS
Derivative assets		0	0
LIABILITIES
Derivative liabilities		0	0
Derivatives Not Designated as Hedging Instruments [Member] | Carrying Amount [Member]
ASSETS
Derivative assets		690,000,000	681,000,000
LIABILITIES
Derivative liabilities		426,000,000	289,000,000
Derivatives Not Designated as Hedging Instruments [Member] | Fair Value [Member]
ASSETS
Derivative assets		690,000,000	681,000,000
Derivative assets, Netting Adjustment		(227,000,000)	(349,000,000)
LIABILITIES
Derivative liabilities		426,000,000	289,000,000
Derivative liabilities, Netting Adjustment		(596,000,000)	(568,000,000)
Derivatives Not Designated as Hedging Instruments [Member] | Fair Value [Member] | Level 1 [Member]
ASSETS
Derivative assets		81,000,000	99,000,000
LIABILITIES
Derivative liabilities		73,000,000	94,000,000
Derivatives Not Designated as Hedging Instruments [Member] | Fair Value [Member] | Level 2 [Member]
ASSETS
Derivative assets		828,000,000	918,000,000
LIABILITIES
Derivative liabilities		940,000,000	763,000,000
Derivatives Not Designated as Hedging Instruments [Member] | Fair Value [Member] | Level 3 [Member]
ASSETS
Derivative assets		8,000,000	13,000,000
LIABILITIES
Derivative liabilities		$ 9,000,000	$ 0
[1]	Total loans held for sale include real estate — residential mortgage loans held for sale at fair value of $58 million at June 30, 2018 , and $71 million at December 31, 2017

Securities - Details of Securit

Securities - Details of Securities (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
SECURITIES AVAILABLE FOR SALE
Amortized Cost	$ 18,057	$ 18,546
Gross Unrealized Gains	10	16
Gross Unrealized Losses	700	423
Fair Value	17,367	18,139
HELD-TO-MATURITY SECURITIES
Amortized Cost	12,277	11,830
Gross Unrealized Gains	1	7
Gross Unrealized Losses	543	272
Fair Value	11,735	11,565
US Treasury and Government [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	150	159
Gross Unrealized Gains	0	0
Gross Unrealized Losses	4	2
Fair Value	146	157
US States and Political Subdivisions Debt Securities [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	7	9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	7	9
Collateralized Mortgage Obligations [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	14,435	14,985
Gross Unrealized Gains	5	10
Gross Unrealized Losses	546	335
Fair Value	13,894	14,660
HELD-TO-MATURITY SECURITIES
Amortized Cost	7,699	8,055
Gross Unrealized Gains	1	0
Gross Unrealized Losses	372	224
Fair Value	7,328	7,831
Residential Mortgage Backed Securities [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	1,407	1,456
Gross Unrealized Gains	2	3
Gross Unrealized Losses	42	20
Fair Value	1,367	1,439
HELD-TO-MATURITY SECURITIES
Amortized Cost	531	574
Gross Unrealized Gains	0	1
Gross Unrealized Losses	17	4
Fair Value	514	571
Other Debt Obligations [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	17	17
Gross Unrealized Gains	3	3
Gross Unrealized Losses	0	0
Fair Value	20	20
HELD-TO-MATURITY SECURITIES
Amortized Cost	15	15
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	15	15
Other Mortgage-Backed Securities [Member] | Commercial Mortgage Backed Securities [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	2,041	1,920
Gross Unrealized Gains	0	0
Gross Unrealized Losses	108	66
Fair Value	1,933	1,854
HELD-TO-MATURITY SECURITIES
Amortized Cost	4,032	3,186
Gross Unrealized Gains	0	6
Gross Unrealized Losses	154	44
Fair Value	$ 3,878	$ 3,148

Securities - Available for Sale

Securities - Available for Sale Securities (Unrealized Loss Position) (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Held-to-maturity securities:
Temporarily impaired securities, fair value, less than 12 months	$ 11,738	$ 10,991
Temporarily impaired securities, gross unrealized losses, less than 12 months	340	125
Temporarily impaired securities, fair value, 12 months or longer	15,620	16,041
Temporarily impaired securities, gross unrealized losses, 12 months or longer	903	570
Temporarily impaired securities, fair value	27,358	27,032
Temporarily impaired securities, gross unrealized losses	1,243	695
US Treasury and Government [Member]
Securities available for sale:
Fair value, less than 12 months	39	41
Gross unrealized losses, less than 12 months	1	0
Fair value, 12 months or longer	107	116
Gross unrealized losses, 12 months or longer	3	2
Fair value	146	157
Gross unrealized losses	4	2
Collateralized Mortgage Obligations [Member]
Securities available for sale:
Fair value, less than 12 months	5,742	6,153
Gross unrealized losses, less than 12 months	141	74
Fair value, 12 months or longer	7,230	7,270
Gross unrealized losses, 12 months or longer	405	261
Fair value	12,972	13,423
Gross unrealized losses	546	335
Held-to-maturity securities:
Fair value, less than 12 months	2,058	2,201
Gross unrealized losses, less than 12 months	65	27
Fair value, 12 months or longer	5,156	5,599
Gross unrealized losses, 12 months or longer	307	197
Fair value	7,214	7,800
Gross unrealized losses (less than $1 million for other securities)	372	224
Commercial Mortgage Backed Securities [Member]
Securities available for sale:
Fair value, less than 12 months	192	205
Gross unrealized losses, less than 12 months	9	4
Fair value, 12 months or longer	1,593	1,649
Gross unrealized losses, 12 months or longer	99	62
Fair value	1,785	1,854
Gross unrealized losses		66
Held-to-maturity securities:
Fair value, less than 12 months	3,030	1,470
Gross unrealized losses, less than 12 months	104	12
Fair value, 12 months or longer	477	495
Gross unrealized losses, 12 months or longer	50	32
Fair value	3,507	1,965
Gross unrealized losses (less than $1 million for other securities)	154	44
Other Debt Obligations [Member]
Held-to-maturity securities:
Fair value, less than 12 months	9	3
Gross unrealized losses, less than 12 months	0	0
Fair value, 12 months or longer	0	4
Gross unrealized losses, 12 months or longer	0	0
Fair value	9	7
Gross unrealized losses (less than $1 million for other securities)	1	1
Other Mortgage-Backed Securities [Member] | Residential Mortgage Backed Securities [Member]
Securities available for sale:
Fair value, less than 12 months	338	666
Gross unrealized losses, less than 12 months	10	7
Fair value, 12 months or longer	873	702
Gross unrealized losses, 12 months or longer	32	13
Fair value	1,211	1,368
Gross unrealized losses	42	20
Held-to-maturity securities:
Fair value, less than 12 months	330	252
Gross unrealized losses, less than 12 months	10	1
Fair value, 12 months or longer	184	206
Gross unrealized losses, 12 months or longer	7	3
Fair value	514	458
Gross unrealized losses (less than $1 million for other securities)	17	$ 4
Other Mortgage-Backed Securities [Member] | Commercial Mortgage Backed Securities [Member]
Securities available for sale:
Gross unrealized losses	$ 108

Securities - Additional Informa

Securities - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)loanposition	Dec. 31, 2017USD ($)
Debt Securities, Available-for-sale [Line Items]
Loans pledged as collateral	$ 7,900
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Number of fixed rate collateralized mortgage obligations | loan	465
Weighted average maturity collateralized mortgage life	4 years 8 months 8 days
Residential Mortgage Backed Securities [Member] | Agency residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	$ 42	$ 20
Securities in unrealized loss positions, number of positions | position	266
Weighted average maturity mortgage backed securities	3 years 11 months 23 days
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses		$ 66
Commercial Mortgage Backed Securities [Member] | Agency residential mortgage-backed securities [Member]
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	$ 108
Securities in unrealized loss positions, number of positions | position	14
Weighted average maturity mortgage backed securities	4 years 21 days

Securities - Cumulative Credit

Securities - Cumulative Credit Portion of Impairments on Debt Securities (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Cumulative Impairments on Debt Securities, Beginning Balance	$ 4
Impairment recognized in earnings	0
Cumulative Impairments on Debt Securities, Ending Balance	$ 4

Securities - Securities by Matu

Securities - Securities by Maturity (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Amortized Cost of Securities Available for sale, Due in one year or less	$ 113
Amortized Cost of Securities Available for sale, Due after one through five years	12,105
Amortized Cost of Securities Available for sale, Due after five through ten years	5,823
Amortized Cost of Securities Available for sale, Due after ten years	16
Amortized Cost	18,057	$ 18,546
Fair Value of Securities Available for sale, Due in one year or less	113
Fair Value of Securities Available for sale, Due after one through five years	11,602
Fair Value of Securities Available for sale, Due after five through ten years	5,636
Fair Value of Securities Available for sale, Due after ten years	16
Total Fair Value of Securities Available For Sale	17,367	18,139
Amortized Cost of Held-to-Maturity Securities, Due in one year or less	43
Amortized Cost of Held-to-Maturity Securities, Due after one through five years	6,653
Amortized Cost of Held-to-Maturity Securities, Due after five through ten years	5,581
Amortized Cost of Held-to-Maturity Securities, Due after ten years	0
Amortized Cost	12,277	11,830
Fair Value of Held-to-Maturity Securities, Due in one year or less	42
Fair Value of Held-to-Maturity Securities, Due after one through five years	6,410
Fair Value of Held-to-Maturity Securities, Due after five through ten years	5,283
Fair Value of Held-to-Maturity Securities, Due after ten years	0
Total Fair Value of Held-to-Maturity Securities	$ 11,735	$ 11,565

Derivatives and Hedging Activ72

Derivatives and Hedging Activities - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)derivativerating	Dec. 31, 2017USD ($)
Credit Derivatives [Line Items]
Derivative assets after effects of bilateral collateral and master netting agreements	$ 48
Derivative liabilities after effects of bilateral collateral and master netting agreements	1
Derivative assets not designated as hedging instruments after effects of bilateral collateral and master netting agreements, and a reserve for potential future losses	690
Derivative liabilities not designated as hedging instruments after effects of bilateral collateral and master netting agreements, and a reserve for potential future losses	426
Reclassify of after-tax net losses on derivative instruments from AOCI	$ 68
Length of time hedge in cash flow hedge	12 months
Reclassification of net losses related to terminated cash flow hedges from AOCI to income	$ 3
Maximum length of time over which forecasted transactions are hedged, years	10 years
Other Comprehensive income unrealized gain on derivatives arising during period net of tax	$ 44
Cash collateral netted against derivative assets	(127)	$ (23)
Collateral netted against derivative liabilities	251	150
Gross exposure on derivatives, after taking into account the effects of bilateral collateral and master netting agreements	115
Net exposure on derivatives, after taking into account, the effects of bilateral collateral and master netting agreements	218
Over-collateralization on derivatives to broker-dealers and banks, after the application of master netting agreements and collateral	208
Additional collateral held in the form of securities	10
Default reserve associated with uncollateralized contracts	3
Gross exposure on derivatives after taking into account effects of master netting agreements	582
Net exposure on derivatives with clients after application of master netting agreements collateral and related reserve	521
Banking Subsidiary [Member]
Credit Derivatives [Line Items]
Net liability position totaled	290
Derivative assets included in net liability position	143
Derivative liabilities included in net liability position	433
Cash and securities collateral posted	$ 270
Number of credit risk derivatives held | derivative	0
Additional collateral amount	$ 1	0
Banking Subsidiary [Member] | Unsecured Debt [Member]
Credit Derivatives [Line Items]
Number of ratings above noninvestment | rating	4
Banking Subsidiary [Member] | Maximum [Member] | Unsecured Debt [Member]
Credit Derivatives [Line Items]
Payments to terminate contracts (less than for the $1 million)	$ 3	$ 12

Derivatives and Hedging Activ73

Derivatives and Hedging Activities - Fair Values, Volume of Activity and Gain (Loss) Information Related to Derivative Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional Amount	$ 108,651	$ 100,193
Derivative assets, netting adjustments	(219)	(443)
Derivative Assets, net	736	664
Derivative liabilities, netting adjustments	(598)	(616)
Derivative Liabilities, net	357	207
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	29,174	26,478
Derivative Assets	40	82
Derivative Liabilities	2	50
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	79,477	73,715
Derivative Assets	917	1,030
Derivative Liabilities	1,022	857
Interest Rate [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	28,918	26,176
Derivative Assets	37	81
Derivative Liabilities	2	46
Interest Rate [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	66,309	61,390
Derivative Assets	306	641
Derivative Liabilities	421	474
Foreign Exchange [Member] | Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	256	302
Derivative Assets	3	1
Derivative Liabilities	0	4
Foreign Exchange [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	9,378	8,317
Derivative Assets	113	129
Derivative Liabilities	103	120
Commodity [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	2,165	1,687
Derivative Assets	494	255
Derivative Liabilities	484	246
Credit [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	381	315
Derivative Assets	0	1
Derivative Liabilities	12	4
Other [Member] | Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	1,244	2,006
Derivative Assets	4	4
Derivative Liabilities	2	13
Net Derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	108,651	100,193
Derivative Assets, net	738	669
Derivative Liabilities, net	426	291
Counterparty And Cash Collateral Netting [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	0
Derivative Assets, net	(2)	(5)
Derivative Liabilities, net	$ (69)	$ (84)

Derivatives and Hedging Activ74

Derivatives and Hedging Activities - Cumulative Basis Adjustments on Fair Value Hedges (Detail) - Interest Rate [Member] $ in Millions	Jun. 30, 2018USD ($)
Long-term Debt [Member]
Derivatives, Fair Value [Line Items]
Carrying amount of hedged item	$ 9,481
Hedge accounting basis adjustment	(104)
Certificates of Deposit [Member]
Derivatives, Fair Value [Line Items]
Carrying amount of hedged item	347
Hedge accounting basis adjustment	0
Bank Time Deposits [Member]
Derivatives, Fair Value [Line Items]
Carrying amount of hedged item	179
Hedge accounting basis adjustment	0
Derivatives Not Designated as Hedging Instruments [Member] | Long-term Debt [Member]
Derivatives, Fair Value [Line Items]
Hedge accounting basis adjustment	$ (11)

Derivatives and Hedging Activ75

Derivatives and Hedging Activities - Effect of Fair Value and Cash Flow Hedges on Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense — Long-term debt		$ (102)	$ (74)	$ (194)	$ (142)
Interest income — Loans		1,000	948	1,940	1,825
Deposits		(112)	(66)	(203)	(124)
Other income	[1]	99	85	120	117
Other Income [Member] | Cash Flow Hedging [Member]
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Gains (losses) (before tax) recognized in income for hedge ineffectiveness			0		0
Interest Rate [Member] | Interest Expense, Long-Term Debt [Member] | Fair Value Hedging [Member]
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items		22	0	93	0
Recognized on derivatives designated as hedging instruments		(25)	14	(94)	32
Net income (expense) recognized on fair value hedges		(3)	14	(1)	32
Interest Rate [Member] | Interest Expense, Long-Term Debt [Member] | Cash Flow Hedging [Member]
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		1	(1)	0	(2)
Gains (losses) (before tax) recognized in income for hedge ineffectiveness			0		0
Net income (expense) recognized on cash flow hedges		1	(1)	0	(2)
Interest Rate [Member] | Interest Income [Member] | Fair Value Hedging [Member]
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items		0	0	0	0
Recognized on derivatives designated as hedging instruments		0	0	0	0
Net income (expense) recognized on fair value hedges		0	0	0	0
Interest Rate [Member] | Interest Income [Member] | Cash Flow Hedging [Member]
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		(25)	5	(27)	20
Gains (losses) (before tax) recognized in income for hedge ineffectiveness			0
Net income (expense) recognized on cash flow hedges		(25)	5	(27)	20
Interest Rate [Member] | Interest Expense, Deposits [Member] | Fair Value Hedging [Member]
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items		1	0	1	0
Recognized on derivatives designated as hedging instruments		0	0	0	0
Net income (expense) recognized on fair value hedges		1	0	1	0
Interest Rate [Member] | Interest Expense, Deposits [Member] | Cash Flow Hedging [Member]
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		0	0	0	0
Gains (losses) (before tax) recognized in income for hedge ineffectiveness			0		0
Net income (expense) recognized on cash flow hedges		0	0	0	0
Interest Rate [Member] | Other Income [Member] | Fair Value Hedging [Member]
Gain (Loss) on Fair Value Hedges Recognized in Earnings [Abstract]
Recognized on hedged items		0	(5)	0	30
Recognized on derivatives designated as hedging instruments		0	5	0	(30)
Net income (expense) recognized on fair value hedges		0	0	0	0
Interest Rate [Member] | Other Income [Member] | Cash Flow Hedging [Member]
Cash Flow Hedges Derivative Instruments at Fair Value, Net [Abstract]
Realized gains (losses) (pre-tax) reclassified from AOCI into net income		0	0	0	0
Net income (expense) recognized on cash flow hedges		$ 0	$ 0	$ 0	$ 0
[1]	For the three months ended June 30, 2018 , net securities gains totaled less than $1 million. For the three months ended June 30, 2017 , net securities gains totaled $1 million. For the three months ended June 30, 2018 , and June 30, 2017

Derivatives and Hedging Activ76

Derivatives and Hedging Activities - Derivative Instrument Cash Flow Hedge Earning Recognized by Income Statement Location (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	$ (45)	$ 15	$ (131)	$ (10)
Net Gains (Losses) Reclassified From OCI Into Income(a)	(24)	4	(27)	18
Net Gains (Losses) Recognized in Other Income(a)	0	0	0	0
Interest Income [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	(58)	22	(146)	0
Net Gains (Losses) Reclassified From OCI Into Income(a)	(25)	5	(27)	20
Net Gains (Losses) Recognized in Other Income(a)	0	0	0	0
Interest Expense [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Reclassified From OCI Into Income(a)	(1)
Interest Expense [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	2	0	4	0
Net Gains (Losses) Reclassified From OCI Into Income(a)		(1)	0	(2)
Net Gains (Losses) Recognized in Other Income(a)	0	0	0	0
Underwriting Discounts Fees And Commissions [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	1	0	1	0
Net Gains (Losses) Reclassified From OCI Into Income(a)	0	0	0	0
Net Gains (Losses) Recognized in Other Income(a)	0	0	0	0
Other Income [Member] | Foreign Exchange [Member] | Net Investment Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI	10	(7)	10	(10)
Net Gains (Losses) Reclassified From OCI Into Income(a)	0	0	0	0
Net Gains (Losses) Recognized in Other Income(a)	$ 0	$ 0	$ 0	$ 0

Derivatives and Hedging Activ77

Derivatives and Hedging Activities - Pre-Tax Net Gains (Losses) on Derivatives Not Designated as Hedging Instruments (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 27	$ 7	$ 45	$ 19
Interest Rate [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	11	9	22	14
Foreign Exchange [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	11	10	22	21
Commodity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	3	1	6	3
Credit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(14)	(5)	(17)	(9)
Other Credit Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	16	(8)	12	(10)
Corporate Services Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	25	21	50	41
Corporate Services Income [Member] | Interest Rate [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	11	10	20	16
Corporate Services Income [Member] | Foreign Exchange [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	11	10	22	21
Corporate Services Income [Member] | Commodity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	3	1	6	3
Corporate Services Income [Member] | Credit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	2	1
Corporate Services Income [Member] | Other Credit Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer Mortgage Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	2	0	1
Consumer Mortgage Income [Member] | Interest Rate [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer Mortgage Income [Member] | Foreign Exchange [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer Mortgage Income [Member] | Commodity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer Mortgage Income [Member] | Credit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer Mortgage Income [Member] | Other Credit Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	2	0	1
Other Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	2	(16)	(5)	(23)
Other Income [Member] | Interest Rate [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	(1)	2	(2)
Other Income [Member] | Foreign Exchange [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Other Income [Member] | Commodity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Other Income [Member] | Credit [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(14)	(5)	(19)	(10)
Other Income [Member] | Other Credit Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 16	$ (10)	$ 12	$ (11)

Derivatives and Hedging Activ78

Derivatives and Hedging Activities - Fair Value of Derivative Assets by Type (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 611	$ 646
Less: Related collateral	(127)	(23)
Total derivative assets	738	669
Interest Rate [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	215	401
Foreign Exchange [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	66	77
Commodity [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	326	163
Credit [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	0	1
Other [Member]
Credit Derivatives [Line Items]
Derivative assets before collateral	$ 4	$ 4

Derivatives and Hedging Activ79

Derivatives and Hedging Activities - Fair Value of Credit Derivatives Purchased and Sold (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Purchased	$ (2)	$ (3)
Sold	(1)	0
Net	(3)	(3)
Single Name Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Purchased	(1)	(1)
Sold	0	0
Net	(1)	(1)
Traded Credit Default Swap Indices [Member]
Credit Derivatives [Line Items]
Purchased	(1)	(2)
Sold	0	0
Net	(1)	(2)
Other [Member]
Credit Derivatives [Line Items]
Purchased	0	0
Sold	(1)	0
Net	$ (1)	$ 0

Derivatives and Hedging Activ80

Derivatives and Hedging Activities - Credit Derivatives Sold and Held (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Credit Derivatives [Line Items]
Notional Amount	$ 21		$ 15
Average Term (Years)	0 years
Payment / Performance Risk	0.00%		0.00%
Other [Member]
Credit Derivatives [Line Items]
Notional Amount	$ 21		$ 15
Average Term (Years)	10 years 4 months 17 days	3 years 29 days
Payment / Performance Risk	14.13%		6.64%

Derivatives and Hedging Activ81

Derivatives and Hedging Activities - Credit Risk Contingent Feature (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	$ 10
Standard & Poor's, A- Rating [Member] | One Rating Downgrade [Member]
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	2	$ 2
Standard & Poor's, A- Rating [Member] | Two Rating Downgrade [Member]
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	2	2
Standard & Poor's, A- Rating [Member] | Three Rating Downgrade [Member]
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	2	2
Moody's, A3 Rating [Member] | One Rating Downgrade [Member]
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	2	2
Moody's, A3 Rating [Member] | Two Rating Downgrade [Member]
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	2	2
Moody's, A3 Rating [Member] | Three Rating Downgrade [Member]
Credit Derivatives [Line Items]
Additional collateral aggregate fair value	$ 2	$ 2

Mortgage Servicing Assets - Cha

Mortgage Servicing Assets - Changes in Carrying Amount of Mortgage Servicing Assets (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Commercial Mortgage Backed Securities [Member]
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of period	$ 435	$ 369	$ 412	$ 356
Servicing retained from loan sales	29	19	56	47
Purchases	12	7	33	14
Amortization	(25)	(22)	(50)	(44)
Balance at end of period	451	373	451	373
Fair value at end of period	646	495	646	495
Residential Mortgage Backed Securities [Member]
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of period	32	29	31	28
Servicing retained from loan sales	3	1	5	3
Purchases	0	0	0	0
Amortization	(1)	(1)	(2)	(2)
Balance at end of period	34	29	34	29
Fair value at end of period	$ 43	$ 35	$ 43	$ 35

Mortgage Servicing Assets - Sch

Mortgage Servicing Assets - Schedule of Range and Weighted-Average of Significant Unobservable Inputs (Detail) - Discounted Cash Flow [Member] - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Commercial Mortgage Backed Securities [Member] | Minimum [Member]
Servicing Assets at Fair Value [Line Items]
Expected defaults	1.00%	1.00%
Residual cash flows discount rate	7.00%	7.00%
Escrow earn rate	2.40%	1.50%
Servicing cost	$ 150,000,000	$ 150,000,000
Loan assumption rate	0.00%	0.00%
Percentage late	0.00%	0.00%
Commercial Mortgage Backed Securities [Member] | Maximum [Member]
Servicing Assets at Fair Value [Line Items]
Expected defaults	3.00%	3.00%
Residual cash flows discount rate	15.00%	15.00%
Escrow earn rate	3.82%	3.10%
Servicing cost	$ 38,500,000,000	$ 38,500,000,000
Loan assumption rate	3.00%	3.00%
Percentage late	2.00%	2.00%
Commercial Mortgage Backed Securities [Member] | Weighted Average [Member]
Servicing Assets at Fair Value [Line Items]
Expected defaults	1.17%	1.30%
Residual cash flows discount rate	9.06%	8.80%
Escrow earn rate	3.10%	2.50%
Servicing cost	$ 1,431,000,000	$ 1,457,000,000
Loan assumption rate	1.19%	1.24%
Percentage late	0.22%	0.29%
Residential Mortgage Backed Securities [Member] | Minimum [Member]
Servicing Assets at Fair Value [Line Items]
Expected defaults	8.50%	8.50%
Servicing cost	$ 76,000,000	$ 76,000,000
Prepayment speed	8.39%	7.85%
Residential Mortgage Backed Securities [Member] | Maximum [Member]
Servicing Assets at Fair Value [Line Items]
Expected defaults	11.00%	11.00%
Servicing cost	$ 4,385,000,000	$ 3,335,000,000
Prepayment speed	49.39%	21.72%
Residential Mortgage Backed Securities [Member] | Weighted Average [Member]
Servicing Assets at Fair Value [Line Items]
Expected defaults	8.54%	8.55%
Servicing cost	$ 82,380,000	$ 82,180,000
Prepayment speed	9.17%	9.42%

Mortgage Servicing Assets - Add

Mortgage Servicing Assets - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Commercial Mortgage Backed Securities [Member]
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	$ 85	$ 72
Amortization of servicing commercial mortgage loans	50	44
Residential Mortgage Backed Securities [Member]
Servicing Assets at Fair Value [Line Items]
Contractual fee income from servicing commercial mortgage loans	7	7
Amortization of servicing commercial mortgage loans	$ 2	$ 2

Variable Interest Entities - Ad

Variable Interest Entities - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Variable Interest Entity [Line Items]
Investments in operating partnerships	$ 209,000,000		$ 230,000,000
Liabilities related to investments in qualified affordable housing projects	4,000,000		4,000,000
Recurring [Member]
Variable Interest Entity [Line Items]
Alternative Investment	130,000,000		144,000,000
Recurring [Member] | Principal Investments Indirect [Member]
Variable Interest Entity [Line Items]
Alternative Investment	109,000,000		124,000,000
LIHTC Investments [Member]
Variable Interest Entity [Line Items]
Investments in operating partnerships	6,176,000,000		6,003,000,000
Liabilities related to investments in qualified affordable housing projects	2,971,000,000		2,943,000,000
Tax credit of investment	78,000,000
LIHTC Investments [Member] | Qualified affordable housing projects investment [Member]
Variable Interest Entity [Line Items]
Liabilities related to investments in qualified affordable housing projects	443,000,000		476,000,000
LIHTC Investments [Member] | Accrued Income And Other Assets [Member]
Variable Interest Entity [Line Items]
Investments in operating partnerships	1,300,000,000
LIHTC Investments [Member] | Investments [Member]
Variable Interest Entity [Line Items]
Amortization of investment	83,000,000	$ 81,000,000
Tax credit of investment	81,000,000
Guaranteed Funds [Member] | Investments [Member]
Variable Interest Entity [Line Items]
VIE, assets that can only be used to settle obligations	0		$ 4,000,000
VIE, liabilities	$ 0

Variable Interest Entities - S

Variable Interest Entities - Summary of Variable Interest Entities Information (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Total Assets	$ 209	$ 230
Total Liabilities	4	4
LIHTC Investments [Member]
Variable Interest Entity [Line Items]
Total Assets	6,176	6,003
Total Liabilities	2,971	2,943
Maximum Exposure to Loss	1,583	1,561
KCC Indirect Investments [Member]
Variable Interest Entity [Line Items]
Total Assets	22,367	26,817
Total Liabilities	426	292
Maximum Exposure to Loss	$ 137	$ 153

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Additional net investment tax credits		$ 14
Percent reduction to income tax provision		2.80%
Tax reform, income tax expense (benefit)				$ 161
Tax reform, low-income housing investments, income tax expense (benefit)				14
Tax reform, change in tax rate, income tax expense (benefit)				$ 147
Tax reform, change in enacted tax rate, percent				7.60%
Tax reform, reclassification from AOCI to retained earnings, tax effect	$ 141
Total income tax expense (benefit), rate	17.60%		28.00%
Combined federal and state statutory tax rate				23.70%	37.20%
Income tax benefit (as a percent)	0.50%
Federal deferred tax asset	$ 389			$ 389	$ 320
Valuation allowance	11			11	$ 15
Key Corp [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits	38			38
First Niagara Bank, N.A. [Member]
Income Tax Contingency [Line Items]
Allocated bad debt deductions	$ 92			$ 92

Acquisition, Divestiture, and88

Acquisition, Divestiture, and Discontinued Operations - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Jun. 29, 2017	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Oct. 02, 2017	Jul. 01, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill			$ 2,516		$ 2,516		$ 2,538
Gain on sale					78	$ 0
Cain Brothers & Company, LLC. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets acquired								$ 30
Goodwill								$ 53
HelloWallet Holdings, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets acquired									$ 12
Goodwill									$ 17
Key Merchant Services, LLC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Intangible assets acquired	$ 95		85		85	95
Goodwill	$ 1					$ 1
Business acquisition, percentage of coting interests acquired	51.00%					51.00%
Business combination, percentage held before acquisition date		49.00%
Business combination, ownership percentage	100.00%					100.00%
Exchange of First Niagara preferred stock for KeyCorp preferred stock		$ 74		$ 69
Business combination, noncash holding gain	$ 64			59
Business combination, estimated fair value of equity interest				5
Measurement-period adjustment, intangible assets				$ 10
Goodwill, subsequent recognition of deferred tax asset			2
Tax adjustment on previous fair value measurements					4
Disposal Group, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale			73
Discontinued Operations [Member] | Government Guaranteed Loans [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loans included in divestiture			$ 1,200		$ 1,200		$ 1,300

Securities Financing Activiti89

Securities Financing Activities - Summarized Securities Financing Agreements (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	$ 0
Total	0
Repurchase agreements	0
Total	0
Counterparty And Cash Collateral Netting [Member]
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	0
Total	0
Repurchase agreements	(252)
Total	(252)
Federal Agency CMOs [Member]
Securities Financing Transaction [Line Items]
Assets pledged as collateral	409
Liabilities pledged as collateral	252
Gross Amounts Presented In Balance Sheets [Member]
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	11	$ 3
Total	11
Repurchase agreements	266
Total	266
Netting Adjustments [Member]
Securities Financing Transaction [Line Items]
Reverse repurchase agreements	(11)
Total	(11)
Repurchase agreements	(14)
Total	$ (14)

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail) - Other Postretirement Benefit Plans [Member]	6 Months Ended
	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Age of employees under condition one	55 years
Period of service under condition one	5 years
Age of employees under condition two	50 years
Period of service under condition two	15 years
Minimum period of service at the time of termination hired before 2001	15 years

Employee Benefits - Net Pension

Employee Benefits - Net Pension Cost (Benefit) for All Funded and Unfunded Plans (Detail) - Pension Plans [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Interest cost on PBO	$ 10	$ 12	$ 20	$ 24
Expected return on plan assets	(13)	(17)	(26)	(34)
Amortization of losses	4	4	8	8
Net pension/postretirement benefit cost	$ 1	$ (1)	$ 2	$ (2)

Trust Preferred Securities Is92

Trust Preferred Securities Issued by Unconsolidated Subsidiaries - Summary of Trust Preferred Securities, Common Stock and Related Debentures (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Stock	$ 1,257	$ 1,257
Debentures adjustments related to financial instrument hedging	44	55
KeyCorp Capital I [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	155
Common Stock	6
Principal Amount of of Debentures, Net of Discount	$ 161
Interest Rate of Trust Preferred Securities and Debentures	3.052%
KeyCorp Capital II [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 101
Common Stock	4
Principal Amount of of Debentures, Net of Discount	$ 105
Interest Rate of Trust Preferred Securities and Debentures	6.875%
KeyCorp Capital III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 130
Common Stock	4
Principal Amount of of Debentures, Net of Discount	$ 134
Interest Rate of Trust Preferred Securities and Debentures	7.75%
HNC Statutory Trust III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 18
Common Stock	1
Principal Amount of of Debentures, Net of Discount	$ 19
Interest Rate of Trust Preferred Securities and Debentures	3.73%
Willow Grove Statutory Trust I [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 18
Common Stock	1
Principal Amount of of Debentures, Net of Discount	$ 19
Interest Rate of Trust Preferred Securities and Debentures	3.651%
HNC Statutory Trust IV [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 16
Common Stock	1
Principal Amount of of Debentures, Net of Discount	$ 17
Interest Rate of Trust Preferred Securities and Debentures	3.639%
Westbank Capital Trust II [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 7
Common Stock	0
Principal Amount of of Debentures, Net of Discount	$ 7
Interest Rate of Trust Preferred Securities and Debentures	4.515%
Westbank Capital Trust III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 7
Common Stock	0
Principal Amount of of Debentures, Net of Discount	$ 7
Interest Rate of Trust Preferred Securities and Debentures	4.515%
Business Trusts [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities, Net of Discount	$ 452	463
Common Stock	17	17
Principal Amount of of Debentures, Net of Discount	$ 469	$ 480
Interest Rate of Trust Preferred Securities and Debentures	5.374%	4.977%
Treasury Rate [Member] | KeyCorp Capital II [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	0.20%
Treasury Rate [Member] | KeyCorp Capital III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	0.25%
London Interbank Offered Rate (LIBOR) [Member] | KeyCorp Capital I [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	0.74%
London Interbank Offered Rate (LIBOR) [Member] | HNC Statutory Trust III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	1.40%
London Interbank Offered Rate (LIBOR) [Member] | Willow Grove Statutory Trust I [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	1.31%
London Interbank Offered Rate (LIBOR) [Member] | HNC Statutory Trust IV [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	1.28%
London Interbank Offered Rate (LIBOR) [Member] | Westbank Capital Trust II and III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	2.19%
Redemption upon either tax or a capital treatment event [Member] | Treasury Rate [Member] | Keycorp Capital II and III [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Basis spread on variable rate	0.50%

Contingent Liabilities and Gu93

Contingent Liabilities and Guarantees - Guarantees (Detail) $ in Millions	Jun. 30, 2018USD ($)
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	$ 10,892
Liability Recorded	176
Written Put Options [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	2,764
Liability Recorded	88
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	3,124
Liability Recorded	72
Recourse Agreement with FNMA [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	3,547
Liability Recorded	7
Residential Mortgage Reserve [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	1,454
Liability Recorded	6
Return Guarantee Agreement with LIHTC Investors [Member]
Guarantor Obligations [Line Items]
Maximum Potential Undiscounted Future Payments	3
Liability Recorded	$ 3

Contingent Liabilities and Gu94

Contingent Liabilities and Guarantees - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)
Commitments Contingencies And Guarantees [Line Items]
Default guarantees, value	$ 176
Written Put Options [Member]
Commitments Contingencies And Guarantees [Line Items]
Default guarantees, value	$ 88
Weighted average life of written put options	3 years
Standby Letters of Credit [Member]
Commitments Contingencies And Guarantees [Line Items]
Remaining weighted-average life of standby letters of credit in years	2 years
Default guarantees, value	$ 72
Recourse Agreement with FNMA [Member]
Commitments Contingencies And Guarantees [Line Items]
Weighted-average remaining term for outstanding commercial mortgage loans in years	7 years 10 months 24 days
Unpaid principal balance outstanding of loans sold	$ 12,500
Maximum potential amount of undiscounted future payments possibly required as percentage of principal balance of loans outstanding	28.00%
Default guarantees, value	$ 7
Residential Mortgage Reserve [Member]
Commitments Contingencies And Guarantees [Line Items]
Unpaid principal balance outstanding of loans sold	$ 4,800
Maximum potential amount of undiscounted future payments possibly required as percentage of principal balance of loans outstanding	30.00%
Weighted-average loan to value ratio (as a percent)	72.00%
Liability for estimated repurchase obligations on loans sold	$ 6
Default guarantees, value	$ 6
Return Guarantee Agreement with LIHTC Investors [Member]
Commitments Contingencies And Guarantees [Line Items]
Compliance period of property	15 years
Default guarantees, value	$ 3
Default Guarantees [Member]
Commitments Contingencies And Guarantees [Line Items]
Default guarantees, value	$ 1
Minimum [Member] | Standby Letters of Credit [Member]
Commitments Contingencies And Guarantees [Line Items]
Remaining actual life of standby letters of credit	1 year
Minimum [Member] | Low [Member]
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	0.00%
Minimum [Member] | Moderate [Member]
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	30.00%
Minimum [Member] | High [Member]
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	70.00%
Maximum [Member] | Standby Letters of Credit [Member]
Commitments Contingencies And Guarantees [Line Items]
Remaining actual life of standby letters of credit	16 years
Maximum [Member] | Low [Member]
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	30.00%
Maximum [Member] | Moderate [Member]
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	70.00%

Accumulated Other Comprehensi95

Accumulated Other Comprehensive Income - Changes in AOCI (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance			$ 15,025
Other comprehensive income before reclassification, net of income taxes	$ (110)	$ 48	(327)	$ 41
Amounts reclassified from accumulated other comprehensive income, net of income taxes	21	0	26	(6)
Other amounts reclassified from AOCI, net of income taxes	(5)		(5)
Total other comprehensive income (loss), net of tax	(94)	48	(306)	35
Ending Balance	15,102		15,102
Unrealized Gains (Losses) on Securities Available for Sale [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(461)	(179)	(311)	(185)
Other comprehensive income before reclassification, net of income taxes	(66)	34	(216)	40
Amounts reclassified from accumulated other comprehensive income, net of income taxes	0	0	0	0
Other amounts reclassified from AOCI, net of income taxes	0		0
Total other comprehensive income (loss), net of tax	(66)	34	(216)	40
Ending Balance	(527)	(145)	(527)	(145)
Unrealized Gains (Losses) on Derivative Financial Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(149)	(38)	(86)	(14)
Other comprehensive income before reclassification, net of income taxes	(35)	9	(100)	(6)
Amounts reclassified from accumulated other comprehensive income, net of income taxes	18	(2)	20	(11)
Other amounts reclassified from AOCI, net of income taxes	0		0
Total other comprehensive income (loss), net of tax	(17)	7	(80)	(17)
Ending Balance	(166)	(31)	(166)	(31)
Foreign Currency Translation Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	7	(2)	9	(3)
Other comprehensive income before reclassification, net of income taxes	(9)	6	(11)	7
Amounts reclassified from accumulated other comprehensive income, net of income taxes	0	0	0	0
Other amounts reclassified from AOCI, net of income taxes	(5)		(5)
Total other comprehensive income (loss), net of tax	(14)	6	(16)	7
Ending Balance	(7)	4	(7)	4
Net Pension and Postretirement Benefit Costs [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(388)	(335)	(391)	(339)
Other comprehensive income before reclassification, net of income taxes	0	(1)	0	0
Amounts reclassified from accumulated other comprehensive income, net of income taxes	3	2	6	5
Other amounts reclassified from AOCI, net of income taxes	0		0
Total other comprehensive income (loss), net of tax	3	1	6	5
Ending Balance	(385)	(334)	(385)	(334)
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(991)	(554)	(779)	(541)
Total other comprehensive income (loss), net of tax			(306)	35
Ending Balance	$ (1,085)	$ (506)	$ (1,085)	$ (506)

Accumulated Other Comprehensi96

Accumulated Other Comprehensive Income - Reclassifications Out of AOCI (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income — Loans	$ 1,000	$ 948	$ 1,940	$ 1,825
Interest expense — Long-term debt	(102)	(74)	(194)	(142)
Income (loss) from continuing operations before income taxes	590	579	1,076	1,009
Income taxes	103	158	165	252
Personnel expense	586	553	1,180	1,110
INCOME (LOSS) FROM CONTINUING OPERATIONS	479	407	895	732
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivative Financial Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from continuing operations before income taxes	(24)	4	(27)	18
Income taxes	(6)	2	(7)	7
INCOME (LOSS) FROM CONTINUING OPERATIONS	(18)	2	(20)	11
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Pension and Postretirement Benefit Costs [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income (loss) from continuing operations before income taxes	(4)	(4)	(8)	(8)
Income taxes	(1)	(2)	(2)	(3)
INCOME (LOSS) FROM CONTINUING OPERATIONS	(3)	(2)	(6)	(5)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Net Pension and Postretirement Benefit Costs [Member] | Amortization of Losses [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Personnel expense	(4)	(4)	(8)	(8)
Interest Income [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivative Financial Instruments [Member] | Interest Rate [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income — Loans	(25)	5	(27)	20
Interest Expense [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized Gains (Losses) on Derivative Financial Instruments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense — Long-term debt	$ 1	$ (1)	$ 0	$ (2)

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Detail)	Jul. 30, 2018USD ($)$ / shares	Sep. 30, 2018$ / shares	Jun. 30, 2018USD ($)$ / sharesshares	Jun. 30, 2017$ / shares	Jun. 30, 2018USD ($)$ / sharesshares	Jun. 30, 2017USD ($)$ / shares	Jun. 28, 2018USD ($)	Dec. 31, 2017shares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Repurchase of common shares					$ 279,000,000	$ 196,000,000
Cash dividends declared on common shares (in usd per share) | $ / shares			$ 0.12	$ 0.095	$ 0.225	$ 0.180
Depository Shares, Series D [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Shares issued					$ 525,000,000
Series D Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Depository receipt ratio			0.04		0.04
Dividend payable per share (in usd per share) | $ / shares			$ 12.50		$ 12.50
Preferred stock, par value (in usd per share) | $ / shares			$ 1		$ 1
Preferred stock, liquidation preference, value			$ 25,000		$ 25,000
Preferred stock, liquidation preference (in usd per share) | $ / shares			$ 1,000		$ 1,000
Preferred stock, shares authorized (in shares) | shares			21,000		21,000			21,000
Preferred stock, shares outstanding (in shares) | shares			21,000		21,000			21,000
Depository Shares, Series E [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Shares issued					$ 500,000,000
Series E Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Depository receipt ratio			0.025		0.025
Dividend payable per share (in usd per share) | $ / shares			$ 0.382813		$ 0.382813
Preferred stock, par value (in usd per share) | $ / shares			$ 1		$ 1
Preferred stock, liquidation preference, value			$ 1,000		$ 1,000
Preferred stock, liquidation preference (in usd per share) | $ / shares			$ 25		$ 25
Preferred stock, shares authorized (in shares) | shares			500,000		500,000			500,000
Preferred stock, shares outstanding (in shares) | shares			500,000		500,000			500,000
2017 Capital Plan [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Authorized amount of share repurchases			$ 800,000,000		$ 800,000,000
Common shares repurchased, value			126,000,000
Repurchase of common shares			123,000,000
Employee equity compensation program Common Share repurchases			$ 3,000,000
Cash dividends declared on common shares (in usd per share) | $ / shares			$ 0.12
2018 Capital Plan [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Authorized amount of share repurchases							$ 1,225,000,000
Scenario, Forecast [Member] | 2018 Capital Plan [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Proposed increase in cash dividends declared on common shares, per share | $ / shares		$ 0.17
Subsequent Event [Member] | Depository Shares, Series F [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Shares issued	$ 425,000,000
Subsequent Event [Member] | Series F Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Depository receipt ratio	0.025
Preferred stock, par value (in usd per share) | $ / shares	$ 1
Preferred stock, liquidation preference, value	$ 1,000
Preferred stock, liquidation preference (in usd per share) | $ / shares	$ 25

Line of Business Results - Addi

Line of Business Results - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018Segment
Segment Reporting [Abstract]
Number of operating segments	2

Line of Business Results - Fina

Line of Business Results - Financial Information of Business Groups (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)employee	Jun. 30, 2017USD ($)employee	Jun. 30, 2018USD ($)employee	Jun. 30, 2017USD ($)employee
Segment Reporting Information [Line Items]
Net interest income (TE)	$ 987	$ 987	$ 1,939	$ 1,916
Noninterest income	660	653	1,261	1,230
Total revenue (TE)	1,647	1,640	3,200	3,146
Provision for credit losses	64	66	125	129
Depreciation and amortization expense	99	93	203	186
Other noninterest expense	894	902	1,796	1,822
Income (loss) from continuing operations before income taxes	590	579	1,076	1,009
Allocated income taxes and TE adjustments	111	172	181	277
INCOME (LOSS) FROM CONTINUING OPERATIONS	479	407	895	732
Income (loss) from discontinued operations, net of taxes	3	5	5	5
NET INCOME (LOSS)	482	412	900	737
Less: Net income (loss) attributable to noncontrolling interests	0	0	0	1
NET INCOME (LOSS) ATTRIBUTABLE TO KEY	482	412	900	736
AVERAGE BALANCES
Loans and leases	88,644	86,502	87,790	86,318
Total assets	136,378	132,491	135,651	132,615
Deposits	104,003	102,779	103,283	102,430
OTHER FINANCIAL DATA
Net loan charge-offs	$ 60	$ 66	$ 114	$ 124
Return on average allocated equity	12.78%	10.74%	12.06%	9.70%
Return on average allocated equity	12.86%	10.87%	12.13%	9.77%
Average full-time equivalent employees | employee	18,376	18,344	18,458	18,365
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net interest income (TE)	$ 980	$ 980	$ 1,926	$ 1,909
Noninterest income	596	661	1,204	1,244
Total revenue (TE)	1,576	1,641	3,130	3,153
Provision for credit losses	65	66	126	130
Depreciation and amortization expense	61	51	125	99
Other noninterest expense	920	908	1,845	1,798
Income (loss) from continuing operations before income taxes	530	616	1,034	1,126
Allocated income taxes and TE adjustments	94	170	175	329
INCOME (LOSS) FROM CONTINUING OPERATIONS	436	446	859	797
Income (loss) from discontinued operations, net of taxes	0	0	0	0
NET INCOME (LOSS)	436	446	859	797
Less: Net income (loss) attributable to noncontrolling interests	0	0	0	1
NET INCOME (LOSS) ATTRIBUTABLE TO KEY	436	446	859	796
AVERAGE BALANCES
Loans and leases	88,628	86,469	87,785	86,286
Total assets	136,011	131,753	135,252	131,746
Deposits	103,947	102,796	103,217	102,489
OTHER FINANCIAL DATA
Net loan charge-offs	$ 60	$ 66	$ 114	$ 124
Return on average allocated equity	22.22%	22.99%	22.10%	20.57%
Return on average allocated equity	22.22%	22.99%	22.10%	20.57%
Average full-time equivalent employees | employee	13,351	13,264	13,441	13,228
Operating Segments [Member] | Key Community Bank [Member]
Segment Reporting Information [Line Items]
Net interest income (TE)	$ 715	$ 676	$ 1,403	$ 1,305
Noninterest income	281	322	551	583
Total revenue (TE)	996	998	1,954	1,888
Provision for credit losses	38	47	86	94
Depreciation and amortization expense	28	28	57	56
Other noninterest expense	611	607	1,233	1,185
Income (loss) from continuing operations before income taxes	319	316	578	553
Allocated income taxes and TE adjustments	75	118	137	206
INCOME (LOSS) FROM CONTINUING OPERATIONS	244	198	441	347
Income (loss) from discontinued operations, net of taxes	0	0	0	0
NET INCOME (LOSS)	244	198	441	347
Less: Net income (loss) attributable to noncontrolling interests	0	0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO KEY	244	198	441	347
AVERAGE BALANCES
Loans and leases	47,984	47,477	47,833	47,282
Total assets	51,866	51,441	51,736	51,215
Deposits	80,930	79,601	80,440	79,375
OTHER FINANCIAL DATA
Net loan charge-offs	$ 34	$ 47	$ 76	$ 90
Return on average allocated equity	20.22%	16.59%	18.43%	14.70%
Return on average allocated equity	20.22%	16.59%	18.43%	14.70%
Average full-time equivalent employees | employee	10,619	10,558	10,642	10,511
Operating Segments [Member] | Key Corporate Bank [Member]
Segment Reporting Information [Line Items]
Net interest income (TE)	$ 277	$ 312	$ 549	$ 616
Noninterest income	265	285	552	559
Total revenue (TE)	542	597	1,101	1,175
Provision for credit losses	28	19	42	36
Depreciation and amortization expense	33	22	67	42
Other noninterest expense	293	275	573	561
Income (loss) from continuing operations before income taxes	188	281	419	536
Allocated income taxes and TE adjustments	21	57	45	133
INCOME (LOSS) FROM CONTINUING OPERATIONS	167	224	374	403
Income (loss) from discontinued operations, net of taxes	0	0	0	0
NET INCOME (LOSS)	167	224	374	403
Less: Net income (loss) attributable to noncontrolling interests	0	0	0	(1)
NET INCOME (LOSS) ATTRIBUTABLE TO KEY	167	224	374	404
AVERAGE BALANCES
Loans and leases	39,710	37,704	38,989	37,696
Total assets	47,213	44,131	46,386	44,128
Deposits	21,057	21,145	20,937	21,074
OTHER FINANCIAL DATA
Net loan charge-offs	$ 26	$ 19	$ 38	$ 33
Return on average allocated equity	23.07%	31.66%	26.21%	28.27%
Return on average allocated equity	23.07%	31.66%	26.21%	28.27%
Average full-time equivalent employees | employee	2,537	2,364	2,540	2,374
Operating Segments [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Net interest income (TE)	$ (12)	$ (8)	$ (26)	$ (12)
Noninterest income	50	54	101	102
Total revenue (TE)	38	46	75	90
Provision for credit losses	(1)	0	(2)	0
Depreciation and amortization expense	0	1	1	1
Other noninterest expense	16	26	39	52
Income (loss) from continuing operations before income taxes	23	19	37	37
Allocated income taxes and TE adjustments	(2)	(5)	(7)	(10)
INCOME (LOSS) FROM CONTINUING OPERATIONS	25	24	44	47
Income (loss) from discontinued operations, net of taxes	0	0	0	0
NET INCOME (LOSS)	25	24	44	47
Less: Net income (loss) attributable to noncontrolling interests	0	0	0	2
NET INCOME (LOSS) ATTRIBUTABLE TO KEY	25	24	44	45
AVERAGE BALANCES
Loans and leases	934	1,288	963	1,308
Total assets	36,932	36,181	37,130	36,403
Deposits	1,960	2,050	1,840	2,040
OTHER FINANCIAL DATA
Net loan charge-offs	$ 1	$ 0	$ 1	$ 1
Return on average allocated equity	78.96%	61.31%	66.22%	56.36%
Return on average allocated equity	78.96%	61.31%	66.22%	56.36%
Average full-time equivalent employees | employee	195	342	259	343
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Net interest income (TE)	$ 7	$ 7	$ 13	$ 7
Noninterest income	64	(8)	57	(14)
Total revenue (TE)	71	(1)	70	(7)
Provision for credit losses	(1)	0	(1)	(1)
Depreciation and amortization expense	38	42	78	87
Other noninterest expense	(26)	(6)	(49)	24
Income (loss) from continuing operations before income taxes	60	(37)	42	(117)
Allocated income taxes and TE adjustments	17	2	6	(52)
INCOME (LOSS) FROM CONTINUING OPERATIONS	43	(39)	36	(65)
Income (loss) from discontinued operations, net of taxes	3	5	5	5
NET INCOME (LOSS)	46	(34)	41	(60)
Less: Net income (loss) attributable to noncontrolling interests	0	0	0	0
NET INCOME (LOSS) ATTRIBUTABLE TO KEY	46	(34)	41	(60)
AVERAGE BALANCES
Loans and leases	16	33	5	32
Total assets	367	738	399	869
Deposits	56	(17)	66	(59)
OTHER FINANCIAL DATA
Net loan charge-offs	$ 0	$ 0	$ 0	$ 0
Return on average allocated equity	2.41%	(2.11%)	1.02%	(1.77%)
Return on average allocated equity	2.58%	(1.84%)	1.16%	(1.64%)
Average full-time equivalent employees | employee	5,025	5,080	5,017	5,137

Revenue from Contracts with 100

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 342		$ 646
Noninterest income	660	$ 653	1,261	$ 1,230
Contract assets	0		0
Contract liabilities	0		0
Trust And Investment Services [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	109		212
Investment Banking And Debt Placement [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	68		115
Service Charges On Deposit Accounts [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	91		179
Cards And Payments [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	69		130
Other Noninterest Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5		10
Noninterest income	204		457
Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	596	661	1,204	1,244
Operating Segments [Member] | Community Banking [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	215		418
Noninterest income	281	322	551	583
Operating Segments [Member] | Community Banking [Member] | Trust And Investment Services [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	91		179
Operating Segments [Member] | Community Banking [Member] | Investment Banking And Debt Placement [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	1		1
Operating Segments [Member] | Community Banking [Member] | Service Charges On Deposit Accounts [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	78		153
Operating Segments [Member] | Community Banking [Member] | Cards And Payments [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	40		75
Operating Segments [Member] | Community Banking [Member] | Other Noninterest Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	5		10
Operating Segments [Member] | Key Corporate Bank [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	127		228
Noninterest income	265	$ 285	552	$ 559
Operating Segments [Member] | Key Corporate Bank [Member] | Trust And Investment Services [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	18		33
Operating Segments [Member] | Key Corporate Bank [Member] | Investment Banking And Debt Placement [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	67		114
Operating Segments [Member] | Key Corporate Bank [Member] | Service Charges On Deposit Accounts [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	13		26
Operating Segments [Member] | Key Corporate Bank [Member] | Cards And Payments [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	29		55
Operating Segments [Member] | Key Corporate Bank [Member] | Other Noninterest Income [Member]
Disaggregation of Revenue [Line Items]
Total revenue from contracts with customers	$ 0		$ 0