Huntington Bancshares (HBAN) 10-Q 30 Apr 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2018shares
Document and Entity Information [Abstract]
Entity Registrant Name	HUNTINGTON BANCSHARES INC/MD
Entity Central Index Key	49,196
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)	1,101,795,768

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks		$ 1,069	$ 1,520
Interest-bearing deposits in banks		46	47
Trading account securities		85	86
Available-for-sale securities		14,607	14,869
Held-to-maturity securities		8,789	9,091
Other Securities, Fair Value		602	600
Loans held for sale (includes $426 and $413 respectively, measured at fair value)(1)	[1]	506	488
Loans and leases (includes $86 and $93 respectively, measured at fair value)(1)	[1]	71,163	70,117
Allowance for loan and lease losses		(721)	(691)
Net loans and leases		70,442	69,426
Bank owned life insurance		2,480	2,466
Premises and equipment		847	864
Goodwill		1,993	1,993
Other intangible assets		333	346
Servicing rights		246	238
Accrued income and other assets		2,201	2,151
Total assets		104,246	104,185
Liabilities
Deposits		79,471	77,041
Short-term borrowings		2,854	5,056
Long-term debt		8,618	9,206
Accrued expenses and other liabilities		1,995	2,068
Total liabilities		92,938	93,371
Shareholders’ equity
Preferred Stock, Value, Issued		1,203	1,071
Common stock		11	11
Capital surplus		10,025	9,707
Less treasury shares, at cost		(34)	(35)
Accumulated other comprehensive loss		(677)	(528)
Retained earnings		780	588
Total shareholders’ equity		11,308	10,814
Total liabilities and shareholders’ equity		$ 104,246	$ 104,185
Common shares authorized (par value of $0.01) (in shares)		1,500,000,000	1,500,000,000
Common shares issued (in shares)		1,104,988,531	1,075,294,946
Common shares outstanding (in shares)		1,101,795,768	1,072,026,681
Treasury shares outstanding (in shares)		3,192,763	3,268,265
Preferred stock, authorized shares (in shares)		6,617,808	6,617,808
Preferred shares issued (in shares)		2,707,571	2,702,571
Preferred shares outstanding (in shares)		740,500	1,098,006
[1]	Amounts represent loans for which Huntington has elected the fair value option.

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets
Loans held for sale, fair value	$ 426	$ 413
Loans and leases, fair value	$ 86	$ 93
Shareholders’ equity
Common stock, par value	$ 0.01	$ 0.01

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest and fee income:
Loans and leases	$ 756	$ 676
Available-for-sale securities
Taxable	70	71
Tax-exempt	23	19
Held-to-maturity securities—taxable	54	45
Interest Income, Securities, Operating, Other, Taxable	6	5
Interest Income, Securities, Operating, Other, Tax Exempt	0	0
Other	5	4
Total interest income	914	820
Interest expense:
Deposits	60	35
Short-term borrowings	19	6
Federal Home Loan Bank advances	0	0
Subordinated notes and other long-term debt	65	49
Total interest expense	144	90
Net interest income	770	730
Provision for credit losses	66	68
Net interest income after provision for credit losses	704	662
Service charges on deposit accounts	86	83
Cards and payment processing income	53	47
Mortgage banking income	26	32
Trust and investment management services	44	39
Insurance income	21	20
Capital markets fees	19	14
Bank owned life insurance income	15	18
Gain on sale of loans	8	13
Net gains on sales of securities	0	0
Other noninterest income	42	46
Total noninterest income	314	312
Personnel costs	376	382
Outside data processing and other services	73	87
Equipment	40	47
Net occupancy	41	68
Professional services	11	18
Marketing	8	14
Deposit and other insurance expense	18	20
Amortization of intangibles	14	14
Other noninterest expense	52	57
Total noninterest expense	633	707
Income before income taxes	385	267
Provision for income taxes	59	59
Net income	326	208
Dividends on preferred shares	12	19
Net income applicable to common shares	$ 314	$ 189
Average common shares—basic (in shares)	1,083,836	1,086,374
Average common shares—diluted (in shares)	1,124,778	1,108,617
Per common share:
Net income—basic (in usd per share)	$ 0.29	$ 0.17
Net income—diluted (in usd per share)	0.28	0.17
Cash dividends declared (in usd per share)	$ 0.11	$ 0.08
OTTI losses for the periods presented:
Total OTTI losses	$ 0	$ 0
Noncredit-related portion of loss recognized in OCI	0	0
Impairment losses recognized in earnings on available-for-sale securities	$ 0	$ 0

Condensed Consolidated Stateme5

Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 326	$ 208
Unrealized gains (losses) on available-for-sale securities:
Non-credit-related impairment recoveries (losses) on debt securities not expected to be sold	0	1
Unrealized net gains (losses) on available-for-sale securities arising during the period, net of reclassification for net realized gains and losses	149	(10)
Total unrealized gains (losses) on available-for-sale securities	(149)	11
Unrealized gains (losses) on cash flow hedging derivatives, net of reclassifications to income	0	(1)
Change in accumulated unrealized losses for pension and other post-retirement obligations	1	0
Other comprehensive income (loss), net of tax	(148)	10
Comprehensive income	$ 178	$ 218

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Capital Surplus	Treasury Stock	Accumulated Other Comprehensive Loss	Retained Earnings (Deficit)	Preferred Stock	Series A Preferred Stock	Series A Preferred StockRetained Earnings (Deficit)	Series B Preferred Stock	Series B Preferred StockRetained Earnings (Deficit)	Series C Preferred Stock	Series C Preferred StockRetained Earnings (Deficit)	Series E Preferred Stock [Member]	Series D Preferred Stock	Series D Preferred StockRetained Earnings (Deficit)
Balance, beginning of period (in shares) at Dec. 31, 2016		1,088,641		(2,953)
Balance, beginning of period at Dec. 31, 2016	$ 10,308	$ 11	$ 9,881	$ (27)	$ (401)	$ (227)	$ 1,071
Comprehensive Income:
Net income	208					208
Other comprehensive income (loss)	10				10
Cash dividends declared:
Common stock, dividend	(87)					(87)
Preferred stock, dividend								$ (8)	$ (8)	$ 0	$ 0	$ (2)	$ (2)		$ (9)	$ (9)
Recognition of the fair value of share-based compensation	(2)		(2)
Other share-based compensation activity (in shares)		1,338
Other share-based compensation activity	18		19			(1)
Other (in shares)		7		87
Other	1		1
Balance, end of period (in shares) at Mar. 31, 2017		1,090,000		(3,000)
Balance, end of period at Mar. 31, 2017	10,437	$ 11	9,899	$ (27)	(391)	(126)	1,071
Balance, beginning of period (in shares) at Dec. 31, 2017		1,075,295		(3,268)
Balance, beginning of period at Dec. 31, 2017	10,814	$ 11	9,707	$ (35)	(528)	588	1,071
Comprehensive Income:
Net income	326					326
Other comprehensive income (loss)	(148)				(148)
Cash dividends declared:
Common stock, dividend	(121)					(121)
Preferred stock, dividend										$ 0	$ 0	$ (2)	$ (2)		$ (9)	$ (9)
Stock Issued During Period, Value, New Issues	495													$ 495
Stock Repurchased and Retired During Period, Shares		3,007
Stock Repurchased and Retired During Period, Value	48		48
Conversion of Stock, Amount Converted	0		(363)				(363)
Conversion of Stock, Shares		30,330
Recognition of the fair value of share-based compensation	15		15
Other share-based compensation activity (in shares)		2,371
Other share-based compensation activity	(15)		(12)			(3)
Other (in shares)				(76)
Other	1			$ 1
Balance, end of period (in shares) at Mar. 31, 2018		1,105,000		(3,000)
Balance, end of period at Mar. 31, 2018	11,308	$ 11	$ 10,025	$ (34)	$ (677)	$ 780	$ 1,203
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	(1)
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash dividends declared:
Common stock, Cash dividend per share (in usd per share)	$ 0.11	$ 0.08
Series A Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	0	21.25
Series B Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	11.05	9.31
Series C Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	14.69	14.69
Series D Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	$ 15.63	$ 15.63

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net income	$ 326	$ 208
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	66	68
Depreciation and amortization	105	211
Share-based compensation expense	15	(2)
Deferred income tax expense (benefit)	93	(20)
Net gains on sales of securities	0	0
Impairment losses recognized in earnings on available-for-sale securities	0	0
Net Change in:
Trading account securities	1	35
Loans held for sale	(27)	24
Accrued income and other assets	(237)	54
Accrued expense and other liabilities	(49)	(188)
Other, net	1	6
Net cash provided by (used in) operating activities	294	396
Investing activities
Change in interest bearing deposits in banks	22	17
Proceeds from:
Maturities and calls of available-for-sale securities	462	116
Maturities of held-to-maturity securities	174	279
Sales of available-for-sale securities	203	165
Purchases of available-for-sale securities	(507)	(882)
Purchases of held-to-maturity securities	0	(9)
Net proceeds from sales of portfolio loans	76	119
Net loan and lease activity, excluding sales and purchases	(1,137)	(437)
Purchases of premises and equipment	(16)	(55)
Proceeds from sales of other real estate	8	6
Purchases of loans and leases	(68)	(44)
Other, net	9	(6)
Net cash provided by (used in) investing activities	(776)	(736)
Financing activities
Increase (decrease) in deposits	2,430	1,815
Increase (decrease) in short-term borrowings	(2,181)	(2,433)
Net proceeds from issuance of long-term debt	51	1,029
Maturity/redemption of long-term debt	(572)	(48)
Dividends paid on preferred stock	(19)	(19)
Dividends paid on common stock	(118)	(87)
Payments for Repurchase of Common Stock	(48)	0
Proceeds from stock options exercised	3	5
Net proceeds from issuance of preferred stock	495	0
Payments related to tax-withholding for share based compensation awards	(10)	0
Other, net	0	3
Net cash provided by (used for) financing activities	31	265
Increase (decrease) in cash a cash equivalents	(451)	(75)
Cash and cash equivalents at beginning of period	1,520	1,385
Cash and cash equivalents at end of period	1,069	1,310
Supplemental disclosures:
Interest paid	159	86
Income taxes paid (refunded)	11	1
Non-cash activities
Loans transferred to held-for-sale from portfolio	110	159
Loans transferred to portfolio from held-for-sale	31	0
Transfer of loans to OREO	6	10
Available For Sale Securities Transferred To Held To Maturity Securities	2,833	0
Payments To Acquire Other Securities	(2)	(5)
Held To Maturity Securities Transferred To Available For Sale	$ 2,707	$ 0

ACCOUNTING STANDARDS UPDATE

ACCOUNTING STANDARDS UPDATE	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
ACCOUNTING STANDARDS UPDATE	ACCOUNTING STANDARDS UPDATE Accounting standards adopted in current period Standard Summary of guidance Effects on financial statements ASU 2014-09 - Revenue from Contracts with Customers (Topic 606): Issued May 2014 - Topic 606 supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance. - Requires an entity to recognize revenue upon 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. - Also requires additional qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers - Guidance sets forth a five step approach for revenue recognition. - Huntington adopted the new guidance on January 1, 2018 using the modified retrospective approach. - Management's analysis included: (a) Identification of all revenue streams included in the financial statements; (b) Determination of scope exclusions to identify ‘in-scope’ revenue streams; (c) Determination of size, timing, and amount of revenue recognition for in-scope items; (d) Identification of contracts for further analysis; and (e) Completion of a review of certain contracts to evaluate the potential impact of the new guidance. - Key revenue streams identified include service charges on deposit accounts, credit card and payment processing income, trust and investment management services income, and insurance income. Standard Summary of guidance Effects on financial statements ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities. Issued January 2016 - Improvements to GAAP disclosures including requiring an entity to: (a) Measure its equity investments with changes in the fair value recognized in the income statement. (b) Present separately in OCI the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments (i.e., FVO liability). (c) Use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. (d) Assess deferred tax assets related to a net unrealized loss on AFS securities in combination with the entity’s other deferred tax assets. - Huntington adopted the new guidance in the on January 1, 2018. - Amendments are applied as a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. - Huntington reclassified $19 million of equity securities from AFS Securities to Other Securities on the Unaudited Condensed Consolidated Balance Sheets and reclassified unrealized gains of $1 million from AOCI to Retained Earnings. Prior periods have been adjusted to present these securities as Other Securities to facilitate comparison. ASU 2016-15 - Classification of Certain Cash Receipts and Cash Payments. Issued August 2016 - Clarifies guidance on the classification of certain cash receipts and payments in the statement of cash flows. - Provides consistent principles for evaluating the classification of cash payments and receipts in the statement of cash flows to reduce diversity in practice with respect to several types of cash flows. - Huntington adopted the new guidance on January 1, 2018. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. ASU 2017-07 - Improving the Presentation of Net Periodic Pension Cost and Periodic Postretirement Benefit Cost. Issued March 2017 - Requires that an employer report the service cost component of the pension cost and postretirement benefit cost in the same line items as other compensation costs arising from services rendered by the pertinent employees during the period. - Other components of the net benefit cost should be presented or disclosed separately in the income statement from the service cost component. - Huntington adopted the new guidance on January 1, 2018. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. ASU 2017-09 - Stock Compensation Modification Accounting. Issued May 2017 - Reduces the current diversity in practice and provides explicit guidance pertaining to the provisions of modification accounting. - Clarifies that an entity should account for effects of modification unless the fair value, vesting conditions and the classification of the modified award are the same as the original awards immediately before the original award is modified. - Huntington adopted the new guidance on January 1, 2018. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. Standard Summary of guidance Effects on financial statements ASU 2017-12 - Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities. Issued August 2017 - Aligns the entity’s risk management activities and financial reporting for hedging relationships. - Requires an entity to present the earnings effect of the hedging instrument in the same income statement line item in which the earnings effect of the hedged item is reported. - Refines measurement techniques for hedges of benchmark interest rate risk. - Eliminates the separate measurement and reporting of hedge ineffectiveness. - Allows stated amount of assets in a closed portfolio to be fair value hedged by excluding proportion of hedged item related to prepayments, defaults and other events. - Eases hedge effectiveness testing including an option to perform qualitative testing. - For cash flow and net investment hedges, the cumulative-effect adjustment related to eliminating the separate measurement of ineffectiveness should be recognized in AOCI with a corresponding adjustment to retained earnings. - Huntington adopted the new guidance on January 1, 2018. The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. - Huntington reclassified $2.8 billion securities eligible to be hedged under the last-of-layer method from held-to-maturity to available-for-sale and recognized $26 million of fair value loss (net of tax) within OCI. ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220) Issued Feb 2018 - Allows an entity to elect a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from TCJA. - The amount of that reclassification should include the effect of changes of tax rate on the deferred tax amount, any related valuation allowance and other income tax effects on the items in AOCI. - Requires an entity to state if an election to reclassify the tax effect to retained earnings is made along with the description of other income tax effects that are reclassified from AOCI. - Effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years with earl y adoption permitted. - Huntington early adopted the guidance effective to 4Q 2017. Accounting standards yet to be adopted Standard Summary of guidance Effects on financial statements ASU 2016-02 - Leases. Issued February 2016 - New lease accounting model for lessors and lessees. For lessees, virtually all leases will be required to be recognized on the balance sheet by recording a right-of-use asset and lease liability. Subsequent accounting for leases varies depending on whether the lease is classified as an operating lease or a finance lease. - Accounting applied by a lessor is largely unchanged from that applied under the existing guidance. - Requires additional qualitative and quantitative disclosures with the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. - Effective for the fiscal period beginning after December 15, 2018, with early application permitted. - Management intends to adopt the guidance on January 1, 2019, and has formed a working group comprised of associates from different disciplines, including Procurement, Real Estate, and Credit Administration, to evaluate the impact of the standard where Huntington is a lessee or lessor, as well as any impact to borrower’s financial statements. - Management is currently assessing the impact of the new guidance on Huntington's Unaudited Condensed Consolidated Financial Statements, including working with associates engaged in the procurement of goods and services used in the entity’s operations, and reviewing contractual arrangements for embedded leases in an effort to identify Huntington’s full lease population. - Huntington will recognize right-of-use assets and lease liabilities for virtually all of its operating lease commitments. Standard Summary of guidance Effects on financial statements ASU 2016-13 - Financial Instruments - Credit Losses. Issued June 2016 - Eliminates the probable recognition threshold for credit losses on financial assets measured at amortized cost. - Requires those financial assets to be presented at the net amount expected to be collected (i.e., net of expected credit losses). - Measurement of expected credit losses should be based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. - Effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018. - Adoption will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. - Management intends to adopt the guidance on January 1, 2020 and has formed a working group comprised of teams from different disciplines including credit and finance to evaluate the requirements of the new standard and the impact it will have on our processes. - The early stages of this evaluation include a review of existing credit models to identify areas where existing credit models used to comply with other regulatory requirements may be leveraged and areas where new impairment models may be required. ASU 2017-04 - Simplifying the Test for Goodwill Impairment. Issued January 2017 - Simplifies the goodwill impairment test by eliminating Step 2 of the goodwill impairment process, which requires an entity to determine the implied fair value of its goodwill by assigning fair value to all its assets and liabilities. - Entities will instead recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. - Entities will still have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. - Effective for annual and interim goodwill tests performed in fiscal years beginning after December 15, 2019. Early adoption is permitted. - The amendment is not expected to have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements.

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying Unaudited Condensed Consolidated Financial Statements of Huntington reflect all adjustments consisting of normal recurring accruals which are, in the opinion of Management, necessary for a fair statement of the consolidated financial position, the results of operations, and cash flows for the periods presented. These Unaudited Condensed Consolidated Financial Statements have been prepared according to the rules and regulations of the SEC and, therefore, certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted. The Notes to Consolidated Financial Statements appearing in Huntington’s 2017 Form 10-K, which include descriptions of significant accounting policies, as updated by the information contained in this report, should be read in conjunction with these interim financial statements. For statement of cash flow purposes, cash and cash equivalents are defined as the sum of “Cash and due from banks” which includes amounts on deposit with the Federal Reserve and “Federal funds sold and securities purchased under resale agreements.” In conjunction with applicable accounting standards, all material subsequent events have been either recognized in the Unaudited Condensed Consolidated Financial Statements or disclosed in the Notes to Unaudited Condensed Consolidated Financial Statements. Certain amounts reported in prior periods have been reclassified to conform to the current period presentation.

LOANS _ LEASES AND ALLOWANCE FO

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES	LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES Loans and leases which Huntington has the intent and ability to hold for the foreseeable future, or until maturity or payoff, are classified in the Unaudited Condensed Consolidated Balance Sheets as loans and leases. Except for loans which are either accounted for at fair value or purchased credit-impaired, loans are carried at the principal amount outstanding, net of unamortized premiums and discounts and deferred loan fees and costs, which resulted in a net balance of $359 million and $334 million at March 31, 2018 and December 31, 2017 , respectively. Loan and Lease Portfolio Composition The following table provides a detailed listing of Huntington’s loan and lease portfolio at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) March 31, 2018 December 31, 2017 Loans and leases: Commercial and industrial $ 28,622 $ 28,107 Commercial real estate 7,412 7,225 Automobile 12,146 12,100 Home equity 9,987 10,099 Residential mortgage 9,357 9,026 RV and marine finance 2,549 2,438 Other consumer 1,090 1,122 Loans and leases $ 71,163 $ 70,117 Allowance for loan and lease losses (721 ) (691 ) Net loans and leases $ 70,442 $ 69,426 Nonaccrual and Past Due Loans Loans are considered past due when the contractual amounts due with respect to principal and interest are not received within 30 days of the contractual due date. See Note 1 “Significant Accounting Policies” to the consolidated financial statements of the Annual Report on Form 10-K for the year ended December 31, 2017 for a description of the accounting policies related to the NALs. The following table presents NALs by loan class at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) March 31, December 31, Commercial and industrial $ 190 $ 161 Commercial real estate 30 29 Automobile 5 6 Home equity 75 68 Residential mortgage 82 84 RV and marine finance 1 1 Other consumer — — Total nonaccrual loans $ 383 $ 349 The following table presents an aging analysis of loans and leases, including past due loans and leases, by loan class at March 31, 2018 and December 31, 2017 : March 31, 2018 Past Due (1) Loans Accounted for Under FVO Total Loans 90 or (dollar amounts in millions) 30-59 60-89 90 or Total Current Commercial and industrial $ 39 $ 13 $ 65 $ 117 $ 28,505 $ — $ 28,622 $ 9 (2) Commercial real estate 13 — 6 19 7,393 — 7,412 1 Automobile 66 13 8 87 12,058 1 12,146 6 Home equity 55 20 62 137 9,848 2 9,987 15 Residential mortgage 89 37 115 241 9,034 82 9,357 69 (3) RV and marine finance 8 2 1 11 2,537 1 2,549 2 Other consumer 9 4 4 17 1,073 — 1,090 4 Total loans and leases $ 279 $ 89 $ 261 $ 629 $ 70,448 $ 86 $ 71,163 $ 106 December 31, 2017 Past Due (1) Purchased Loans Accounted for Under FVO Total Loans 90 or (dollar amounts in millions) 30-59 60-89 90 or Total Current Commercial and industrial 35 14 65 114 27,954 39 — 28,107 9 (2) Commercial real estate 10 1 11 22 7,201 2 — 7,225 3 Automobile 89 18 10 117 11,982 — 1 12,100 7 Home equity 49 19 60 128 9,969 — 2 10,099 18 Residential mortgage 129 48 118 295 8,642 — 89 9,026 72 (3) RV and marine finance 11 3 2 16 2,421 — 1 2,438 1 Other consumer 12 5 5 22 1,100 — — 1,122 5 Total loans and leases $ 335 $ 108 $ 271 $ 714 $ 69,269 $ 41 $ 93 $ 70,117 $ 115 (1) NALs are included in this aging analysis based on the loan's past due status. (2) Amounts include Huntington Technology Finance administrative lease delinquencies. (3) Amounts include mortgage loans insured by U.S. government agencies. Allowance for Credit Losses Huntington maintains two reserves, both of which reflect Management’s judgment regarding the appropriate level necessary to absorb probable and estimable credit losses inherent in our loan and lease portfolio as of the balance sheet date: the ALLL and the AULC. Combined, these reserves comprise the total ACL. The determination of the ACL requires significant estimates, including the timing and amounts of expected future cash flows on impaired loans and leases, consideration of current economic conditions, and historical loss experience pertaining to pools of homogeneous loans and leases, all of which may be susceptible to change. See Note 1 “Significant Accounting Policies” to the consolidated financial statements of the Annual Report on Form 10-K for the year ended December 31, 2017 for a description of the accounting policies related to the ACL. The ACL is increased through a provision for credit losses that is charged to earnings, based on Management’s quarterly evaluation and is reduced by charge-offs, net of recoveries. The following table presents ALLL and AULC activity by portfolio segment for the three-month periods ended March 31, 2018 and 2017 . (dollar amounts in millions) Commercial Consumer Total Three-month period ended March 31, 2018: ALLL balance, beginning of period $ 482 $ 209 $ 691 Loan charge-offs (23 ) (50 ) (73 ) Recoveries of loans previously charged-off 20 15 35 Provision for loan and lease losses 36 32 68 ALLL balance, end of period $ 515 $ 206 $ 721 AULC balance, beginning of period $ 84 $ 3 $ 87 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (2 ) — (2 ) AULC balance, end of period $ 82 $ 3 $ 85 ACL balance, end of period $ 597 $ 209 $ 806 (dollar amounts in millions) Commercial Consumer Total Three-month period ended March 31, 2017: ALLL balance, beginning of period $ 451 $ 187 $ 638 Loan charge-offs (24 ) (46 ) (70 ) Recoveries of loans previously charged-off 18 13 31 Provision for loan and lease losses 35 39 74 ALLL balance, end of period $ 480 $ 193 $ 673 AULC balance, beginning of period $ 87 $ 11 $ 98 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 2 (8 ) (6 ) AULC balance, end of period $ 89 $ 3 $ 92 ACL balance, end of period $ 569 $ 196 $ 765 Credit Quality Indicators See Note 4 “Loans / Leases and Allowance for Credit Losses” to the consolidated financial statements of the Annual Report on Form 10-K for the year ended December 31, 2017 for a description of the credit quality indicators Huntington utilizes for monitoring credit quality and for determining an appropriate ACL level. To facilitate the monitoring of credit quality for C&I and CRE loans, and for purposes of determining an appropriate ACL level for these loans, Huntington utilizes the following internally defined categories of credit grades: • Pass - Higher quality loans that do not fit any of the other categories described below. • OLEM - The credit risk may be relatively minor yet represents a risk given certain specific circumstances. If the potential weaknesses are not monitored or mitigated, the loan may weaken or the collateral may be inadequate to protect Huntington’s position in the future. For these reasons, Huntington considers the loans to be potential problem loans. • Substandard - Inadequately protected loans by the borrower’s ability to repay, equity, and/or the collateral pledged to secure the loan. These loans have identified weaknesses that could hinder normal repayment or collection of the debt. It is likely Huntington will sustain some loss if any identified weaknesses are not mitigated. • Doubtful - Loans that have all of the weaknesses inherent in those loans classified as Substandard, with the added elements of the full collection of the loan is improbable and that the possibility of loss is high. The categories above, which are derived from standard regulatory rating definitions, are assigned upon initial approval of the loan or lease and subsequently updated as appropriate. Commercial loans categorized as OLEM, Substandard, or Doubtful are considered Criticized loans. Commercial loans categorized as Substandard or Doubtful are both considered Classified loans. The following table presents each loan and lease class by credit quality indicator at March 31, 2018 and December 31, 2017 . March 31, 2018 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 26,719 $ 747 $ 1,142 $ 14 $ 28,622 Commercial real estate 7,049 222 139 2 7,412 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,114 $ 4,338 $ 1,395 $ 298 $ 12,145 Home equity 6,247 3,025 631 82 9,985 Residential mortgage 5,976 2,591 621 87 9,275 RV and marine finance 1,529 866 104 49 2,548 Other consumer 408 549 96 37 1,090 December 31, 2017 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 26,268 $ 694 $ 1,116 $ 29 $ 28,107 Commercial real estate 6,909 200 115 1 7,225 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,102 $ 4,312 $ 1,390 $ 295 $ 12,099 Home equity 6,352 3,024 617 104 10,097 Residential mortgage 5,697 2,581 605 54 8,937 RV and marine finance 1,433 863 96 45 2,437 Other consumer 428 540 143 11 1,122 (1) Excludes loans accounted for under the fair value option. (2) Reflects updated customer credit scores. (3) Reflects deferred fees and costs, loans in process, etc. Impaired Loans See Note 1 “Significant Accounting Policies” to the consolidated financial statements of the Annual Report on Form 10-K for the year ended December 31, 2017 for a description of accounting policies related to impaired loans. The following tables present the balance of the ALLL attributable to loans by portfolio segment individually and collectively evaluated for impairment and the related loan and lease balance at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) Commercial Consumer Total ALLL at March 31, 2018: Portion of ALLL balance: Attributable to loans individually evaluated for impairment $ 36 $ 9 $ 45 Attributable to loans collectively evaluated for impairment 479 197 676 Total ALLL balance $ 515 $ 206 $ 721 Loan and Lease Ending Balances at March 31, 2018: (1) Portion of loan and lease ending balance: Individually evaluated for impairment $ 670 $ 610 $ 1,280 Collectively evaluated for impairment 35,364 34,433 69,797 Total loans and leases evaluated for impairment $ 36,034 $ 35,043 $ 71,077 (1) Excludes loans accounted for under the fair value option. (dollar amounts in millions) Commercial Consumer Total ALLL at December 31, 2017: Portion of ALLL balance: Attributable to purchased credit-impaired loans $ — $ — $ — Attributable to loans individually evaluated for impairment 32 9 41 Attributable to loans collectively evaluated for impairment 450 200 650 Total ALLL balance: $ 482 $ 209 $ 691 Loan and Lease Ending Balances at December 31, 2017: (1) Portion of loan and lease ending balances: Attributable to purchased credit-impaired loans $ 41 $ — $ 41 Individually evaluated for impairment 607 616 1,223 Collectively evaluated for impairment 34,684 34,076 68,760 Total loans and leases evaluated for impairment $ 35,332 $ 34,692 $ 70,024 (1) Excludes loans accounted for under the fair value option. The following tables present by class the ending, unpaid principal balance, and the related ALLL, along with the average balance and interest income recognized only for impaired loans and leases: (1) March 31, 2018 Three Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 243 $ 271 $ — $ 264 $ 5 Commercial real estate 71 91 — 63 2 Automobile — — — — — Home equity — — — — — Residential mortgage — — — — — RV and marine finance — — — — — Other consumer — — — — — With an allowance recorded: Commercial and industrial 314 349 34 286 3 Commercial real estate 42 48 2 47 — Automobile 37 41 2 36 1 Home equity 335 386 14 334 3 Residential mortgage 307 335 4 308 3 RV and marine finance 2 3 — 2 — Other consumer 6 6 2 7 — Total Commercial and industrial (3) 557 620 34 550 8 Commercial real estate (4) 113 139 2 110 2 Automobile (2) 37 41 2 36 1 Home equity (5) 335 386 14 334 3 Residential mortgage (5) 307 335 4 308 3 RV and marine finance (2) 2 3 — 2 — Other consumer (2) 6 6 2 7 — December 31, 2017 Three Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 284 $ 311 $ — $ 276 $ 4 Commercial real estate 56 81 — 86 2 Automobile — — — — — Home equity — — — — — Residential mortgage — — — — — RV and marine finance — — — — — Other consumer — — — — — With an allowance recorded: Commercial and industrial 257 280 29 334 2 Commercial real estate 51 51 3 69 — Automobile 36 40 2 32 1 Home equity 334 385 14 323 4 Residential mortgage 308 338 4 339 3 RV and marine finance 2 3 — — — Other consumer 8 8 2 4 — Total Commercial and industrial (3) 541 591 29 610 6 Commercial real estate (4) 107 132 3 155 2 Automobile (2) 36 40 2 32 1 Home equity (5) 334 385 14 323 4 Residential mortgage (5) 308 338 4 339 3 RV and marine finance (2) 2 3 — — — Other consumer (2) 8 8 2 4 — (1) These tables do not include loans fully charged-off. (2) All automobile, RV and marine finance and other consumer impaired loans included in these tables are considered impaired due to their status as a TDR. (3) At March 31, 2018 and December 31, 2017 , C&I loans of $399 million and $382 million , respectively, were considered impaired due to their status as a TDR. (4) At March 31, 2018 and December 31, 2017 , CRE loans of $92 million and $93 million , respectively, were considered impaired due to their status as a TDR. (5) Includes home equity and residential mortgages considered to be collateral dependent due to their non-accrual status as well as home equity and mortgage loans considered impaired due to their status as a TDR. (6) The differences between the ending balance and unpaid principal balance amounts represent partial charge-offs. TDR Loans TDRs are modified loans where a concession was provided to a borrower experiencing financial difficulties. Loan modifications are considered TDRs when the concessions provided are not available to the borrower through either normal channels or other sources. However, not all loan modifications are TDRs. See Note 4 “Loans / Leases and Allowance for Credit Losses” to the consolidated financial statements of the Annual Report on Form 10-K for the year ended December 31, 2017 for an additional discussion of TDRs. The following table presents, by class and modification type, the number of contracts, post-modification outstanding balance, and the financial effects of the modification for the three-month periods ended March 31, 2018 and 2017 . New Troubled Debt Restructurings During The Three-Month Period Ended (1) March 31, 2018 March 31, 2017 (dollar amounts in millions) Number of Contracts Post-modification Outstanding Balance (2) Financial effects of modification (3) Number of Contracts Post-modification Outstanding Balance (2) Financial effects of modification (3) Commercial and industrial: Interest rate reduction 1 $ — $ — 1 $ — $ — Amortization or maturity date change 238 96 (2 ) 236 113 (1 ) Other 2 — — 3 — — Total Commercial and industrial 241 96 (2 ) 240 113 (1 ) Commercial real estate: Interest rate reduction — — — — — — Amortization or maturity date change 48 32 — 24 31 — Other — — — — — — Total commercial real estate: 48 32 — 24 31 — Automobile: Interest rate reduction 16 — — 14 — — Amortization or maturity date change 411 4 — 477 4 — Chapter 7 bankruptcy 200 2 — 240 2 — Other — — — — — — Total Automobile 627 6 — 731 6 — Home equity: Interest rate reduction 1 — — 8 — — Amortization or maturity date change 85 5 (1 ) 106 5 (1 ) Chapter 7 bankruptcy 51 3 — 87 4 1 Other 7 — — 58 4 — Total Home equity 144 8 (1 ) 259 13 — Residential mortgage: Interest rate reduction — — — 2 — — Amortization or maturity date change 72 9 — 99 11 (1 ) Chapter 7 bankruptcy 10 — — 24 3 — Other 1 — — 16 2 — Total Residential mortgage 83 9 — 141 16 (1 ) RV and marine finance: Interest rate reduction — — — — — — Amortization or maturity date change 3 — — 14 1 — Chapter 7 bankruptcy 16 — — 15 — — Other — — — — — — Total RV and marine finance 19 — — 29 1 — Other consumer: Interest rate reduction 440 2 — 1 — — Amortization or maturity date change — — — 2 — — Chapter 7 bankruptcy 1 — — 1 — — Other — — — — — — Total Other consumer 441 2 — 4 — — Total new troubled debt restructurings 1,603 $ 153 $ (3 ) 1,428 $ 180 $ (2 ) (1) TDRs may include multiple concessions and the disclosure classifications are based on the primary concession provided to the borrower. (2) Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of a restructuring are not significant. (3) Amount represents the financial impact via provision for loan and lease losses as a result of the modification. Pledged Loans and Leases The Bank has access to the Federal Reserve’s discount window and advances from the FHLB of Cincinnati. As of March 31, 2018 and December 31, 2017 , these borrowings and advances are secured by $33.5 billion and $31.7 billion of loans and securities, respectively.

AVAILABLE-FOR-SALE SECURITIES

AVAILABLE-FOR-SALE SECURITIES	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
AVAILABLE-FOR-SALE AND OTHER SECURITIES	AVAILABLE-FOR-SALE SECURITIES Upon adoption of ASU 2017-12, Huntington transferred $2.8 billion of securities eligible to be hedged under the last-of-layer method from the HTM portfolio to the AFS portfolio. At the time of the transfer, $26 million of unrealized losses were recognized in OCI. Concurrently, Huntington transferred $2.7 billion of securities from the AFS portfolio to the HTM portfolio. At the time of the transfer, AOCI included $56 million of unrealized losses attributed to these securities. This loss will be recognized and amortized into interest income over the remaining life of the securities. Contractual maturities of available-for-sale securities at March 31, 2018 and December 31, 2017 were: March 31, 2018 December 31, 2017 (dollar amounts in millions) Amortized Cost Fair Value Amortized Cost Fair Value U.S. Treasury, Federal agency, and other agency securities: U.S. Treasury: 1 year or less $ 5 $ 5 $ 5 $ 5 Total U.S. Treasury 5 5 5 5 Federal agencies: Residential CMO: After 1 year through 5 years 1 1 1 1 After 5 years through 10 years 47 45 90 89 After 10 years 7,742 7,485 6,570 6,394 Total Residential CMO 7,790 7,531 6,661 6,484 Residential MBS: After 1 year through 5 years 6 5 6 6 After 5 years through 10 years 33 33 7 8 After 10 years 700 686 1,358 1,353 Total Residential MBS 739 724 1,371 1,367 Commercial MBS: After 1 year through 5 years 69 67 23 22 After 5 years through 10 years 9 8 151 148 After 10 years 1,775 1,716 2,365 2,317 Total Commercial MBS 1,853 1,791 2,539 2,487 Other agencies: 1 year or less 1 1 2 2 After 1 year through 5 years 8 8 9 9 After 5 years through 10 years 181 178 58 59 Total other agencies 190 187 69 70 Total U.S. Treasury, Federal agency, and other agency securities 10,577 10,238 10,645 10,413 Municipal securities: 1 year or less 153 153 103 103 After 1 year through 5 years 1,129 1,121 1,140 1,134 After 5 years through 10 years 1,738 1,717 1,709 1,704 After 10 years 867 843 940 937 Total municipal securities 3,887 3,834 3,892 3,878 Asset-backed securities: After 1 year through 5 years 80 79 80 80 After 5 years through 10 years 61 60 53 54 After 10 years 294 288 349 333 Total asset-backed securities 435 427 482 467 Corporate debt: 1 year or less 1 1 — — After 1 year through 5 years 67 67 73 74 After 5 years through 10 years 19 20 20 21 After 10 years 13 14 13 14 Total corporate debt 100 102 106 109 Other securities/Sovereign debt: 1 year or less 2 2 1 1 After 1 year through 5 years 4 4 1 1 Total other securities/Sovereign debt 6 6 2 2 Total available-for-sale securities $ 15,005 $ 14,607 $ 15,127 $ 14,869 The following tables provide amortized cost, fair value, and gross unrealized gains and losses recognized in OCI by investment category at March 31, 2018 and December 31, 2017 : Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value March 31, 2018 U.S. Treasury $ 5 $ — $ — $ 5 Federal agencies: Residential CMO 7,790 — (259 ) 7,531 Residential MBS 739 2 (16 ) 724 Commercial MBS 1,853 — (63 ) 1,791 Other agencies 190 — (3 ) 187 Total U.S. Treasury, Federal agency and other agency securities 10,577 2 (341 ) 10,238 Municipal securities 3,887 14 (67 ) 3,834 Asset-backed securities 435 — (8 ) 427 Corporate debt 100 2 — 102 Other securities/Sovereign debt 6 — — 6 Total available-for-sale securities $ 15,005 $ 18 $ (416 ) $ 14,607 Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value December 31, 2017 U.S. Treasury $ 5 $ — $ — $ 5 Federal agencies: Residential CMO 6,661 1 (178 ) 6,484 Residential MBS 1,371 1 (5 ) 1,367 Commercial MBS 2,539 — (52 ) 2,487 Other agencies 69 1 — 70 Total U.S. Treasury, Federal agency and other agency securities 10,645 3 (235 ) 10,413 Municipal securities 3,892 21 (35 ) 3,878 Asset-backed securities 482 1 (16 ) 467 Corporate debt 106 3 — 109 Other securities/Sovereign debt 2 — — 2 Total available-for-sale securities $ 15,127 $ 28 $ (286 ) $ 14,869 The following tables provide detail on investment securities with unrealized losses aggregated by investment category and the length of time the individual securities have been in a continuous loss position as of March 31, 2018 and December 31, 2017 . Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses March 31, 2018 Federal agencies: Residential CMO $ 3,291 $ (71 ) $ 4,027 $ (188 ) $ 7,318 $ (259 ) Residential MBS 648 (16 ) 11 — 659 (16 ) Commercial MBS 322 (9 ) 1,469 (54 ) 1,791 (63 ) Other agencies 107 (1 ) 69 (2 ) 176 (3 ) Total Federal Agency and other agency securities 4,368 (97 ) 5,576 (244 ) 9,944 (341 ) Municipal securities 2,182 (45 ) 623 (22 ) 2,805 (67 ) Asset-backed securities 240 (3 ) 144 (5 ) 384 (8 ) Corporate debt 14 — — — 14 — Other securities/Sovereign debt — — 2 — 2 — Total temporarily impaired securities $ 6,804 $ (145 ) $ 6,345 $ (271 ) $ 13,149 $ (416 ) Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2017 Federal agencies: Residential CMO $ 1,660 $ (19 ) $ 4,520 $ (159 ) $ 6,180 $ (178 ) Residential MBS 1,078 (5 ) 11 — 1,089 (5 ) Commercial MBS 960 (15 ) 1,527 (37 ) 2,487 (52 ) Other agencies 39 — — — 39 — Total Federal Agency and other agency securities 3,737 (39 ) 6,058 (196 ) 9,795 (235 ) Municipal securities 1,681 (21 ) 497 (14 ) 2,178 (35 ) Asset-backed securities 127 (1 ) 173 (15 ) 300 (16 ) Total temporarily impaired securities $ 5,545 $ (61 ) $ 6,728 $ (225 ) $ 12,273 $ (286 ) At March 31, 2018 and December 31, 2017 , the carrying value of investment securities pledged to secure public and trust deposits, trading account liabilities, U.S. Treasury demand notes, and security repurchase agreements totaled $6.5 billion and $6.1 billion , respectively. There were no securities of a single issuer, which are not governmental or government-sponsored, that exceeded 10% of shareholders’ equity at either March 31, 2018 or December 31, 2017 . The following table is a summary of realized securities gains and losses for the three-month periods ended March 31, 2018 and 2017 , respectively. Three Months Ended (dollar amounts in millions) 2018 2017 Gross gains on sales of securities $ 5 $ 1 Gross (losses) on sales of securities (5 ) (1 ) Net gain on sales of securities $ — $ — Security Impairment Huntington evaluates the available-for-sale securities portfolio on a quarterly basis for impairment and conducts a comprehensive security-level assessment on all available-for-sale securities. Impairment would exist when the present value of the expected cash flows are not sufficient to recover the entire amortized cost basis at the balance sheet date. Under these circumstances, any credit impairment would be recognized in earnings. During the 2018 first quarter, Huntington sold the remaining trust preferred CDO securities resulting in a gain of $3 million . As of March 31, 2018 , the Huntington has evaluated available-for-sale securities with gross unrealized losses for impairment and concluded no OTTI is required.

HELD-TO-MATURITY SECURITIES

HELD-TO-MATURITY SECURITIES	3 Months Ended
	Mar. 31, 2018
Held-to-maturity Securities [Abstract]
HELD-TO-MATURITY SECURITIES	HELD-TO-MATURITY SECURITIES These are debt securities that Huntington has the intent and ability to hold until maturity. The debt securities are carried at amortized cost and adjusted for amortization of premiums and accretion of discounts using the interest method. See Note 4 "Available -for-sale- securities" regarding the transfers between the securities portfolios during the 2018 first quarter. Listed below are the contractual maturities of held-to-maturity securities at March 31, 2018 and December 31, 2017 . March 31, 2018 December 31, 2017 (dollar amounts in millions) Amortized Cost Fair Value Amortized Cost Fair Value Federal agencies: Residential CMO: After 5 years through 10 years 39 38 — — After 10 years 2,354 2,291 3,714 3,657 Total Residential CMO 2,393 2,329 3,714 3,657 Residential MBS: After 5 years through 10 years — — 28 28 After 10 years 1,651 1,606 1,021 1,016 Total Residential MBS 1,651 1,606 1,049 1,044 Commercial MBS: After 1 year through 5 years — — 38 37 After 5 years through 10 years 131 128 1 1 After 10 years 4,223 4,101 3,752 3,698 Total Commercial MBS 4,354 4,229 3,791 3,736 Other agencies: After 1 year through 5 years 14 13 7 8 After 5 years through 10 years 215 213 362 360 After 10 years 157 154 163 161 Total other agencies 386 380 532 529 Total Federal agencies and other agencies 8,784 8,544 9,086 8,966 Municipal securities: After 10 years 5 5 5 5 Total municipal securities 5 5 5 5 Total held-to-maturity securities $ 8,789 $ 8,549 $ 9,091 $ 8,971 The following table provides amortized cost, gross unrealized gains and losses, and fair value by investment category at March 31, 2018 and December 31, 2017 . Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value March 31, 2018 Federal agencies: Residential CMO $ 2,393 $ — $ (63 ) $ 2,329 Residential MBS 1,651 — (45 ) 1,606 Commercial MBS 4,354 — (125 ) 4,229 Other agencies 386 — (6 ) 380 Total Federal agencies and other agencies 8,784 — (239 ) 8,544 Municipal securities 5 — — 5 Total held-to-maturity securities $ 8,789 $ — $ (239 ) $ 8,549 Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value December 31, 2017 Federal agencies: Residential CMO $ 3,714 $ 1 $ (58 ) $ 3,657 Residential MBS 1,049 2 (7 ) 1,044 Commercial MBS 3,791 — (55 ) 3,736 Other agencies 532 1 (4 ) 529 Total Federal agencies and other agencies 9,086 4 (124 ) 8,966 Municipal securities 5 — — 5 Total held-to-maturity securities $ 9,091 $ 4 $ (124 ) $ 8,971 The following tables provide detail on HTM securities with unrealized losses aggregated by investment category and the length of time the individual securities have been in a continuous loss position, at March 31, 2018 and December 31, 2017 . Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Gross Unrealized Fair Gross Unrealized Fair Gross Unrealized March 31, 2018 Federal agencies: Residential CMO $ 947 $ (23 ) $ 1,313 $ (40 ) $ 2,260 $ (63 ) Residential MBS 1,606 (45 ) — — 1,606 (45 ) Commercial MBS 3,495 (109 ) 726 (16 ) 4,221 (125 ) Other agencies 297 (4 ) 62 (2 ) 359 (6 ) Total Federal agencies and other agencies 6,345 (181 ) 2,101 (58 ) 8,446 (239 ) Municipal securities — — 5 — 5 — Total temporarily impaired securities $ 6,345 $ (181 ) $ 2,106 $ (58 ) $ 8,451 $ (239 ) Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2017 Federal agencies: Residential CMO $ 2,369 $ (26 ) $ 1,019 $ (32 ) $ 3,388 $ (58 ) Residential MBS 974 (7 ) — — 974 (7 ) Commercial MBS 3,456 (49 ) 253 (6 ) 3,709 (55 ) Other agencies 249 (2 ) 139 (2 ) 388 (4 ) Total Federal agencies and other agencies 7,048 (84 ) 1,411 (40 ) 8,459 (124 ) Municipal securities — — 5 — 5 — Total temporarily impaired securities $ 7,048 $ (84 ) $ 1,416 $ (40 ) $ 8,464 $ (124 ) Security Impairment Huntington evaluates the held-to-maturity securities portfolio on a quarterly basis for impairment. Impairment would exist when the present value of the expected cash flows is not sufficient to recover the entire amortized cost basis at the balance sheet date. Under these circumstances, any impairment would be recognized in earnings. As of March 31, 2018 , Huntington has evaluated held-to-maturity securities with gross unrealized losses for impairment and concluded no OTTI is required.

OTHER SECURITIES (Notes)

OTHER SECURITIES (Notes)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
OTHER SECURITIES [Text Block]	OTHER SECURITIES March 31, 2018 December 31, 2017 (dollar amounts in millions) Amortized Cost Fair Value Amortized Cost Fair Value Other securities, at cost Non-marketable equity securities: Federal Home Loan Bank stock 287 287 287 287 Federal Reserve Bank stock 294 294 294 294 Other securities, at fair value Mutual funds 19 19 18 18 Marketable equity securities 2 2 1 1 Total other securities $ 602 $ 602 $ 600 $ 600 Other securities are primarily composed of FHLB stock and FRB stock (which are carried at cost) and mutual funds and other marketable equity securities (which are carried at fair value, with changes in fair value recognized in other noninterest income). Other securities that are carried at cost are reviewed at least annually for impairment, with valuation adjustments recognized in other noninterest income.

LOAN SALES AND SECURITIZATIONS

LOAN SALES AND SECURITIZATIONS	3 Months Ended
	Mar. 31, 2018
Transfers and Servicing [Abstract]
LOAN SALES AND SECURITIZATIONS	LOAN SALES AND SECURITIZATIONS Residential Mortgage Portfolio The following table summarizes activity relating to residential mortgage loans sold with servicing retained for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 Residential mortgage loans sold with servicing retained $ 843 $ 845 Pretax gains resulting from above loan sales (1) 21 22 (1) Recorded in mortgage banking income. The following table summarizes the changes in MSRs recorded using the amortization method for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 Carrying value, beginning of period $ 191 $ 172 New servicing assets created 10 10 Impairment recovery (charge) 7 2 Amortization (8 ) (6 ) Carrying value, end of period $ 200 $ 178 Fair value, end of period $ 205 $ 179 Weighted-average life (years) 7.0 7.1 MSRs do not trade in an active, open market with readily observable prices. While sales of MSRs occur, the precise terms and conditions are typically not readily available. Therefore, the fair value of MSRs is estimated using a discounted future cash flow model. The model considers portfolio characteristics, contractually specified servicing fees and assumptions related to prepayments, delinquency rates, late charges, other ancillary revenues, costs to service, and other economic factors. Changes in the assumptions used may have a significant impact on the valuation of MSRs. MSR values are very sensitive to movements in interest rates as expected future net servicing income depends on the projected outstanding principal balances of the underlying loans, which can be greatly impacted by the level of prepayments. Huntington economically hedges the value of certain MSRs against changes in value attributable to changes in interest rates using a combination of derivative instruments and trading securities. For MSRs under the amortization method, a summary of key assumptions and the sensitivity of the MSR value to changes in these assumptions at March 31, 2018 , and December 31, 2017 follows: March 31, 2018 December 31, 2017 Decline in fair value due to Decline in fair value due to (dollar amounts in millions) Actual 10% 20% Actual 10% 20% Constant prepayment rate (annualized) 8.42 % $ (9 ) $ (18 ) 8.30 % $ (5 ) $ (10 ) Spread over forward interest rate swap rates 979 bps (8 ) (14 ) 1,049 bps (7 ) (13 ) Additionally, Huntington held MSRs recorded using the fair value method of $12 million and $13 million at March 31, 2018 and 2017 , respectively. The change in fair value representing time decay, payoffs and changes in valuation inputs and assumptions for the three-month periods ended March 31, 2018 and 2017 was $1 million and less than $1 million , respectively. Total servicing, late and other ancillary fees included in mortgage banking income were $15 million and $14 million for the three-month periods ended March 31, 2018 and 2017 , respectively. The unpaid principal balance of residential mortgage loans serviced for third parties was $20.1 billion and $19.8 billion at March 31, 2018 and December 31, 2017 , respectively. Automobile Loans Huntington has retained servicing responsibilities on sold automobile loans and receives annual servicing fees and other ancillary fees on the outstanding loan balances. Automobile loan servicing rights are accounted for using the amortization method. A servicing asset is established at fair value at the time of the sale. The servicing asset is then amortized against servicing income. Impairment, if any, is recognized when carrying value exceeds the fair value as determined by calculating the present value of expected net future cash flows. The primary risk characteristic for measuring servicing assets is payoff rates of the underlying loan pools. Valuation calculations rely on the predicted payoff assumption and, if actual payoffs are faster than expected, then future value could be impaired. Changes in the carrying value of automobile loan servicing rights for the three-month periods ended March 31, 2018 and 2017 , and the fair value at the end of each period were as follows: Three Months Ended (dollar amounts in millions) 2018 2017 Carrying value, beginning of period $ 8 $ 18 Amortization (2 ) (3 ) Carrying value, end of period $ 6 $ 15 Fair value, end of period $ 7 $ 15 Weighted-average contractual life (years) 3.4 4.0 Servicing income amounted to $3 million and $5 million for the three-month periods ending March 31, 2018 , and 2017 . The unpaid principal balance of automobile loans serviced for third parties was $0.9 billion and $1.0 billion at March 31, 2018 and December 31, 2017 , respectively. Small Business Association (SBA) Portfolio The following table summarizes activity relating to SBA loans sold with servicing retained for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 SBA loans sold with servicing retained $ 64 $ 78 Pretax gains resulting from above loan sales (1) 7 6 (1) Recorded in gain on sale of loans. Huntington has retained servicing responsibilities on sold SBA loans and receives annual servicing fees on the outstanding loan balances. SBA loan servicing rights are accounted for using the amortization method. A servicing asset is established at fair value at the time of the sale using a discounted future cash flow model. The servicing asset is then amortized against servicing income. Impairment, if any, is recognized when carrying value exceeds the fair value as determined by calculating the present value of expected net future cash flows. The following table summarizes the changes in the carrying value of the servicing asset for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 Carrying value, beginning of period $ 27 $ 21 New servicing assets created 3 1 Amortization (2 ) (1 ) Carrying value, end of period $ 28 $ 21 Fair value, end of period $ 32 $ 26 Weighted-average life (years) 3.3 3.3 Servicing income amounted to $3 million and $3 million for the three-month periods ending March 31, 2018 , and 2017 , respectively. The unpaid principal balance of SBA loans serviced for third parties was $1.5 billion and $1.4 billion at March 31, 2018 and December 31, 2017 , respectively.

OTHER COMPREHENSIVE INCOME

OTHER COMPREHENSIVE INCOME	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
OTHER COMPREHENSIVE INCOME	OTHER COMPREHENSIVE INCOME The components of Huntington's OCI for the three-month periods ended March 31, 2018 and 2017 , were as follows: Three Months Ended Tax (Expense) (dollar amounts in millions) Pretax Benefit After-tax Noncredit-related impairment recoveries (losses) on debt securities not expected to be sold $ — $ — $ — Unrealized holding gains (losses) on available-for-sale debt securities arising during the period (206 ) 45 (161 ) Less: Reclassification adjustment for net losses (gains) included in net income 15 (3 ) 12 Net change in unrealized holding gains (losses) on available-for-sale debt securities (191 ) 42 (149 ) Net change in pension and other post-retirement obligations 1 — 1 Total other comprehensive income (loss) $ (190 ) $ 42 $ (148 ) Three Months Ended Tax (Expense) (dollar amounts in millions) Pretax Benefit After-tax Noncredit-related impairment recoveries (losses) on debt securities not expected to be sold $ 1 $ — $ 1 Unrealized holding gains (losses) on available-for-sale debt securities arising during the period 9 (3 ) 6 Less: Reclassification adjustment for net losses (gains) included in net income 6 (2 ) 4 Net change in unrealized holding gains (losses) on available-for-sale debt securities 16 (5 ) 11 Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period (2 ) 1 (1 ) Less: Reclassification adjustment for net (gains) losses included in net income 1 (1 ) — Net change in unrealized gains (losses) on derivatives used in cash flow hedging relationships (1 ) — (1 ) Net change in pension and other post-retirement obligations — — — Total other comprehensive income (loss) $ 15 $ (5 ) $ 10 Activity in accumulated OCI for the three -month periods ended March 31, 2018 and 2017 , were as follows: (dollar amounts in millions) Unrealized gains and (losses) on debt securities (1) Unrealized gains and (losses) on cash flow hedging derivatives Unrealized gains (losses) for pension and other post- retirement obligations Total December 31, 2016 $ (193 ) $ (3 ) $ (205 ) $ (401 ) Other comprehensive income before reclassifications 7 (1 ) — 6 Amounts reclassified from accumulated OCI to earnings 4 — — 4 Period change 11 (1 ) — 10 March 31, 2017 $ (182 ) $ (4 ) $ (205 ) $ (391 ) December 31, 2017 $ (278 ) $ — $ (250 ) $ (528 ) Cumulative-effect adjustments (ASU 2016-01) (1 ) — — (1 ) Other comprehensive income before reclassifications (161 ) — — (161 ) Amounts reclassified from accumulated OCI to earnings 12 — 1 13 Period change (149 ) — 1 (148 ) March 31, 2018 $ (428 ) $ — $ (249 ) $ (677 ) (1) AOCI amounts at March 31, 2018 , December 31, 2017 and March 31, 2017 include $147 million , $95 million and $81 million , respectively, of net unrealized gains on securities transferred from the available-for-sale securities portfolio to the held-to-maturity securities portfolio. The net unrealized gains will be recognized in earnings over the remaining life of the security using the effective interest method. The following table presents the reclassification adjustments out of accumulated OCI included in net income and the impacted line items as listed on the Unaudited Condensed Consolidated Statements of Income for the three-month periods ended March 31, 2018 and 2017 : Reclassifications out of accumulated OCI Accumulated OCI components Amounts reclassified from accumulated OCI Location of net gain (loss) reclassified from accumulated OCI into earnings Three Months Ended (dollar amounts in millions) March 31, 2018 March 31, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (3 ) $ (4 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities (12 ) (2 ) Noninterest income - net gains (losses) on sale of securities OTTI recorded — — Noninterest income - net gains (losses) on sale of securities Total before tax (15 ) (6 ) Tax (expense) benefit 3 2 Net of tax $ (12 ) $ (4 ) Gains (losses) on cash flow hedging relationships: Interest rate contracts $ — $ (1 ) Interest income - loans and leases Total before tax — (1 ) Tax (expense) benefit — 1 Net of tax $ — $ — Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ 2 $ (1 ) Noninterest expense - personnel costs Net periodic benefit costs (1 ) 1 Noninterest expense - personnel costs Total before tax 1 — Tax (expense) benefit — — Net of tax $ 1 $ —

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY The following is a summary of Huntington's non-cumulative perpetual preferred stock outstanding as of March 31, 2018 . (dollar amounts in millions, except per share amounts) Series Description Issuance Date Total Shares Outstanding Carrying Amount Dividend Rate Earliest Redemption Date Series B Non-cumulative, non-voting, perpetual 12/28/2011 35,500 23 3-mo. LIBOR + 270 bps 1/15/2017 Series D Non-cumulative, non-voting perpetual 3/21/2016 400,000 386 6.25 % 7/15/2021 Series D Non-cumulative, non-voting perpetual 5/5/2016 200,000 199 6.25 % 7/15/2021 Series C Non-cumulative, non-voting perpetual 8/16/2016 100,000 100 5.875 % 1/15/2022 Series E Non-cumulative, non-voting perpetual 2/27/2018 5,000 495 5.700 % 4/15/2023 Total 740,500 1,203 Series B, D and C of preferred stock has a liquidation value and redemption price per share of $1,000 , plus any declared and unpaid dividends. Series E stock has a liquidation value and redemption price per share of $100,000 , plus any declared and unpaid dividends. All preferred stock has no stated maturity and redemption is solely at the option of the Company. Under current rules, any redemption of the preferred stock is subject to prior approval of the FRB. Preferred A Stock conversion On February 21, 2018 , Huntington elected to effect the conversion of all of its outstanding 8.50% Series A Non-Cumulative Perpetual Convertible Preferred Stock into common stock pursuant to the terms of the Series A Preferred Stock. On February 21, 2018 , the closing sale price of the Common Stock was $15.73 , which marked the 20th trading day in the previous 30 consecutive trading days that the Common Stock closed above $15.54 (which is equal to 130% of the conversion price for the Series A Preferred Stock of $11.95 currently in effect), triggering the right of Huntington Bancshares to elect to mandatorily convert all shares of Series A Preferred Stock into shares of Common Stock in accordance with the terms of the Series A Preferred Stock. On February 22, 2018 , each share of Series A Preferred Stock was converted into 83.668 shares of Common Stock. Upon conversion, the Series A Preferred Stock is no longer outstanding and all rights with respect to the Series A Preferred Stock were ceased and terminated, except the right to receive the number of whole shares and any required cash-in-lieu of fractional shares of Common Stock. Following the conversion, the Series A Preferred Stock shares were delisted from trading on NASDAQ. Preferred E Stock issued and outstanding During the 2018 first quarter, Huntington issued $500 million of preferred stock. Huntington issued 500,000 depositary shares, each depositary shares representing a 1/100th ownership interest in a share of 5.700% Series E Fixed-to-Floating Non-Cumulative Perpetual Preferred Stock (Preferred E Stock), par value $0.01 per share, with a liquidation preference of $100,000 per share (equivalent to $1,000 per depositary share). Each holder of a depositary share will be entitled to all proportional rights and preferences of the Preferred E Stock (including dividend, voting, redemption, and liquidation rights). Costs of $5 million related to the issuance of the Preferred E Stock are reported as a direct deduction from the face amount of the stock. Dividends on the Preferred E Stock will be non-cumulative and payable quarterly in arrears, when, as and if authorized by the Company's board of directors or a duly authorized committee of the board and declared by the Company, at an annual rate of 5.700% per year on the liquidation preference of $100,000 per share, equivalent to $1,000 per depositary share. The dividend payment dates will be the fifteenth day of each January, April, July and October, commencing on July 15, 2018, or the next business day if any such day is not a business day. The Preferred E Stock is perpetual and has no maturity date. Huntington may redeem the Preferred E Stock at its option, (i) in whole or in part, from time to time, on any dividend payment date on or after April 15, 2023 or (ii) in whole but not in part, within 90 days following a change in laws or regulations, in each case, at a redemption price equal to $100,000 per share (equivalent to $1,000 per depositary share), plus any declared and unpaid dividends, without regard to any undeclared dividends, on the Series E Preferred Stock prior to the date fixed for redemption. If Huntington redeems the Preferred E Stock, the depositary will redeem a proportional number of depositary shares. Neither the holders of Preferred E Stock nor holders of depositary shares will have the right to require the redemption or repurchase of the Preferred E Stock or the depositary shares. Any redemption of the Preferred E Stock is subject to Huntington's receipt of any required prior approval by the Board of Governors of the Federal Reserve System. 2017 Comprehensive Capital Analysis and Review (CCAR) On June 28, 2017, Huntington was notified by the Federal Reserve that it had no objection to Huntington's proposed capital actions included in Huntington's capital plan submitted in the 2017 CCAR. These actions included a 38% increase in quarterly dividend per common share to $0.11 , starting in the fourth quarter of 2017, the repurchase of up to $308 million of common stock over the next four quarters (July 1, 2017 through June 30, 2018), subject to authorization by the Board of Directors, and maintaining dividends on the outstanding classes of preferred stock and trust preferred securities.

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Basic earnings per share is the amount of earnings (adjusted for dividends declared on preferred stock) available to each share of common stock outstanding during the reporting period. Diluted earnings per share is the amount of earnings available to each share of common stock outstanding during the reporting period adjusted to include the effect of potentially dilutive common shares. Potentially dilutive common shares include incremental shares issued for stock options, restricted stock units and awards, distributions from deferred compensation plans, and the conversion of the Company’s convertible preferred stock. Potentially dilutive common shares are excluded from the computation of diluted earnings per share during periods in which the effect would be antidilutive. On February 22, 2018, Huntington converted of all its outstanding 8.50% Series A Non-Cumulative Perpetual Convertible Preferred Stock to 30.3 million shares of common stock. Following the conversion, the additional shares were included in average common shares issued and outstanding. The 2018 total diluted average common shares issued and outstanding was impacted by using the if-converted method. The calculation of basic and diluted earnings per share for the three -month periods ended March 31, 2018 and 2017 was as follows: Three Months Ended (dollar amounts in millions, except per share amounts) 2018 2017 Basic earnings per common share: Net income $ 326 $ 208 Preferred stock dividends (12 ) (19 ) Net income available to common shareholders $ 314 $ 189 Average common shares issued and outstanding (000) 1,083,836 1,086,374 Basic earnings per common share $ 0.29 $ 0.17 Diluted earnings per common share: Net income available to common shareholders $ 314 $ 189 Effect of assumed preferred stock conversion — — Net income applicable to diluted earnings per share $ 314 $ 189 Average common shares issued and outstanding (000) 1,083,836 1,086,374 Dilutive potential common shares: Stock options and restricted stock units and awards 19,858 19,139 Shares held in deferred compensation plans 3,228 2,953 Dilutive impact of Preferred Stock 17,856 — Other — 151 Dilutive potential common shares 40,942 22,243 Total diluted average common shares issued and outstanding (000) 1,124,778 1,108,617 Diluted earnings per common share $ 0.28 $ 0.17 There were approximately 0.1 million and 0.9 million of options to purchase shares of common stock outstanding for the three-month periods ended March 31, 2018 and 2017 , respectively. These options were not included in the computation of diluted earnings per share because the effect would be antidilutive.

NON-INTEREST INCOME (Notes)

NON-INTEREST INCOME (Notes)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
NON-INTEREST INCOME	NONINTEREST INCOME Huntington earns a variety of revenue including interest and fees from customers as well as revenues from non-customers. Certain sources of revenue are recognized within interest or fee income and are outside of the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). Other sources of revenue fall within the scope of ASC 606 and are generally recognized within ‘noninterest income’. These revenues are included within various sections of the consolidated financial statements. The following table shows Huntington’s total noninterest income segregated between contracts with customers within the scope of ASC 606 and those within the scope of other GAAP Topics. (dollar amounts in millions) Three Months Ended March 31, 2018 Non-interest income Noninterest income from contracts with customers $ 214 Noninterest income within the scope of other GAAP topics 100 Total noninterest income $ 314 Huntington recognizes revenue when the performance obligations related to the transfer of goods or services under the terms of a contract are satisfied. Some obligations are satisfied at a point in time while others are satisfied over a period of time. Revenue is recognized as the amount of consideration to which Huntington expects to be entitled to in exchange for transferring goods or services to a customer. When consideration includes a variable component, the amount of consideration attributable to variability is included in the transaction price only to the extent it is probable that significant revenue recognized will not be reversed when uncertainty associated with the variable consideration is subsequently resolved. Generally, the variability relating to the consideration is explicitly stated in the contracts, but may also arise from Huntington's customer business practice, for example, waiving certain fees related to customer’s deposit accounts such as non-sufficient funds (“NSF”) fees. Huntington's contracts generally do not contain terms that require significant judgement to determine the variability impacting the transaction price. Revenue is measured as the amount of consideration Huntington expects to be entitled to in exchange for transferring goods or services. Revenue is segregated based on the nature of product and services offered as part of contractual arrangements. Revenue from contracts with customers is broadly segregated as follows. • Service charge on deposit accounts include fees and other charges Huntington receives to provide various services, including but not limited to, maintaining an account with a customer, providing overdraft services, wire transfer, transferring funds, and accepting and executing stop-payment orders. The consideration includes both fixed (e.g., account maintenance fee) and transaction fees (e.g., wire-transfer fee). The fixed fee is recognized over a period of time while the transaction fee is recognized when a specific service (e.g., execution of wire-transfer) is rendered to the customer. Huntington may, from time to time, waive certain fees (e.g., NSF fee) for customers but generally do not reduce the transaction price to reflect variability for future reversals due to the insignificance of the amounts. Waiver of fees reduces the revenue in the period the waiver is granted to the customer. • Cards and payment processing income includes interchange fee earned on debit cards and credit cards. All other fees (e.g. annual fees), and interest income are recognized in accordance with ASC 310. Huntington recognizes interchange fees for services performed related to authorization and settlement of a cardholder’s transaction with a merchant. Revenue is recognized when a cardholder’s transaction is approved and settled. The revenue may be constrained due to inherent uncertainty related to cardholder’s right to return goods and services but the uncertainty is resolved within a short period of time (generally within 30 days) and the amount of returns was not material for the reporting period ended March 31, 2018 . Revenue is not adjusted for such variability, rather returns reduce the amount of interchange revenue in the period the return is made by the customer. Certain volume or transaction based interchange expenses (net of rebates) paid to the payment network reduce the interchange revenue and is presented net on the income statement. Similarly, rewards payable under a reward program to cardholders are recognized as a reduction of the transaction price and are presented net against the interchange revenue. • Trust and investment management services income includes fee income generated from personal, corporate and institutional customers. Huntington also provides investment management services, cash management services as well as tax reporting to customers. Services are rendered over a period of time, over which revenue is recognized. Huntington may also recognize revenue from referring a customer to outside third-parties including mutual fund companies that pay distribution (12b-1) fees and other expenses. 12b-1 fees are received upon initially placing account holder’s funds with a mutual fund company as well as in the future periods as long as the account holder (i.e., the fund investor), remains invested in the fund. The transaction price includes variable consideration which is considered constrained as it is not probable that a significant revenue reversal in the amount of cumulative revenue recognized will not occur. Accordingly, those fees are recognized as revenue when the uncertainty associated with the variable consideration is subsequently resolved, that is, initial fees are recognized in the initial period while the future fees are recognized in future periods. Trust and investment management services also include commissions that are earned for placing a brokerage transaction for execution such as stocks or other investments. Revenue is recognized once the transaction is executed and Huntington is entitled to receive consideration. • Insurance income include agency commissions that are recognized when Huntington sells insurance policies to customers. Huntington is also entitled to renewal commissions and, in some cases, profit sharing which are recognized in subsequent periods. The initial commission is recognized when the insurance policy is sold to a customer. Renewal commission is variable consideration and is recognized in subsequent periods when the uncertainty around variable consideration is subsequently resolved (i.e., when customer renews the policy). Profit sharing is also a variable consideration that is not recognized until the variability surrounding realization of revenue is resolved (i.e., Huntington have reached a minimum volume of sales). Another source of variability is the ability of the policy holder to cancel the policy anytime and in such cases, Huntington may be required, under the terms of the contract, to return part of the commission received. The variability related to cancellation of the policy is not deemed significant and thus, does not impact the amount of revenue recognized. In the event the policyholder chooses to cancel the policy at any time, the revenue for amounts which qualify for claw-back are reversed in the period the cancellation occurs. • Other noninterest income includes a variety of other revenue streams including capital markets revenue, consumer fees and marketing allowance revenue. Revenue is recognized when, or as, a performance obligation is satisfied. Inherent variability in the transaction price is not recognized until the uncertainty affecting the variability is resolved. Control is transferred to a customer either at a point in time or over time. A performance obligation is deemed satisfied when the control over goods or services is transferred to the customer. To determine when control is transferred at a point in time, Huntington considers indicators, including but not limited to the right to payment for the asset, transfer of significant risk and rewards of ownership of the asset and acceptance of asset by the customer. When control is transferred over a period of time, for different performance obligations, either the input or output method is used to determine the progress. The measure of progress used to assess completion of the performance obligation varies between performance obligations and may be based on time throughout the period of service or on the value of goods and services transferred to the customer. As each distinct service or activity is performed, Huntington transfers control to the customer based on the services performed as the customer simultaneously receives the benefits of those services. This timing of revenue recognition aligns with the resolution of any uncertainty related to variable consideration. Costs incurred to obtain a revenue producing contract is expensed when incurred as a practical expedient as the contractual period for majority of contracts is one year or less. Revenue is recorded in the business segment responsible for the related product or service. Fee sharing arrangements exist to allocate portions of such revenue to other business segments involved in selling to, or providing service to, customers. Business segment results are determined based upon management's reporting system, which assigns balance sheet and income statement items to each of the business segments. The process is designed around Huntington's organizational and management structure and, accordingly, the results derived are not necessarily comparable with similar information published by other financial institutions. The following table illustrates the disaggregation by operating segment and major revenue stream and reconciles disaggregated revenue to segment revenue presented in Note 17 . (dollar amounts in millions) Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated Major Revenue Streams Service charges on deposit accounts $ 68 $ 16 $ 1 $ 1 $ — $ 86 Cards and payment processing income 47 2 — — — 49 Trust and investment management services 7 1 — 36 — 44 Insurance income 8 1 — 11 1 21 Other Income 10 — 1 3 — 14 Net revenue from contracts with customers $ 140 $ 20 $ 2 $ 51 $ 1 $ 214 Noninterest income within the scope of other GAAP topics 34 49 1 — 16 100 Total noninterest income $ 174 $ 69 $ 3 $ 51 $ 17 $ 314 Huntington generally provides services for customers in which it acts as principal. Payment terms and conditions vary amongst services and customers, and thus impact the timing and amount of revenue recognition. Some fees may be paid before any service is rendered and accordingly, such fees are deferred until the obligations pertaining to those fees are satisfied. Most Huntington contracts with customers are cancelable by either party without penalty or; they are short-term in nature, with a contract duration of less than one year. Accordingly, most revenue deferred for the reporting period ended March 31, 2018 is expected to be earned within one year. Huntington does not have significant balances of contract assets or contract liabilities and any change in those balances during the reporting period ended March 31, 2018 was determined to be immaterial.

BENEFIT PLANS

BENEFIT PLANS	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
BENEFIT PLANS	. BENEFIT PLANS Huntington sponsors a non-contributory defined benefit pension plan covering substantially all employees hired or rehired prior to January 1, 2010. The plan, which was modified in 2013, no longer accrues service benefits to participants and provides benefits based upon length of service and compensation levels. Huntington's funding policy is to contribute an annual amount that is at least equal to the minimum funding requirements but not more than the amount deductible under the Internal Revenue Code. There is no required minimum contribution for 2018 . In addition, Huntington has a defined benefit post-retirement plan that provides certain healthcare and life insurance benefits to retired employees who have attained the age of 55 and have at least 10 years of vesting service under this plan. For additional information on benefit plans, see the Benefit Plan footnote in our 2017 Form 10-K. The following table shows the components of net periodic (benefit) cost for all plans: Pension Benefits (1) Post-Retirement Benefits (1) Three Months Ended March 31, Three Months Ended March 31, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ 1 $ 1 $ — $ — Interest cost 7 7 — — Expected return on plan assets (12 ) (14 ) — — Amortization of prior service cost — — (1 ) — Amortization of loss 2 2 — — Settlements 3 3 — — Net periodic (benefit) cost $ 1 $ (1 ) $ (1 ) $ — (1) All pension and post-retirement (benefits) costs are recorded in Other Income on the Condensed Consolidated Statements of Income.

FAIR VALUES OF ASSETS AND LIABI

FAIR VALUES OF ASSETS AND LIABILITIES	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
FAIR VALUES OF ASSETS AND LIABILITIES	See Note 18 “Fair Value of Assets and Liabilities” to the Consolidated Financial Statements of the Annual Report on Form 10-K for the year ended December 31, 2017 for a description of the valuation methodologies used for instruments measured at fair value. Assets and liabilities measured at fair value rarely transfer between Level 1 and Level 2 measurements. There were no such transfers during the three-month periods ended March 31, 2018 and 2017 . Assets and Liabilities measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis at March 31, 2018 and December 31, 2017 are summarized below: Fair Value Measurements at Reporting Date Using Netting Adjustments (1) March 31, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Municipal securities $ — $ 2 — — $ 2 Other securities 82 1 — — 83 82 3 — — 85 Available-for-sale securities: U.S. Treasury securities 5 — — — 5 Residential CMOs — 7,531 — — 7,531 Residential MBS — 724 — — 724 Commercial MBS — 1,791 — — 1,791 Other agencies — 187 — — 187 Municipal securities — 604 3,230 — 3,834 Asset-backed securities — 427 — — 427 Corporate debt — 102 — — 102 Other securities/sovereign debt — 6 — — 6 5 11,372 3,230 — 14,607 Other securities 21 — — — 21 Loans held for sale — 426 — — 426 Loans held for investment — 49 37 — 86 MSRs — — 12 — 12 Derivative assets — 350 6 (269 ) 87 Liabilities Derivative liabilities — 433 6 (282 ) 157 Short-term borrowings 1 — — — 1 Fair Value Measurements at Reporting Date Using Netting Adjustments (1) December 31, 2017 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Other securities $ 83 $ 3 — — $ 86 83 3 — — 86 Available-for-sale securities: U.S. Treasury securities 5 — — — 5 Residential CMOs — 6,484 — — 6,484 Residential MBS — 1,367 — — 1,367 Commercial MBS — 2,487 — — 2,487 Other agencies — 70 — — 70 Municipal securities — 711 3,167 — 3,878 Asset-backed securities — 443 24 — 467 Corporate debt — 109 — — 109 Other securities/sovereign debt — 2 — — 2 5 11,673 3,191 — 14,869 Other securities 19 — — — 19 Loans held for sale — 413 — — 413 Loans held for investment — 55 38 — 93 MSRs — — 11 — 11 Derivative assets — 316 6 (190 ) 132 Liabilities Derivative liabilities — 326 5 (245 ) 86 (1) Amounts represent the impact of legally enforceable master netting agreements that allow the Company to settle positive and negative positions and cash collateral held or placed with the same counterparties. The tables below present a rollforward of the balance sheet amounts for the three-month periods ended March 31, 2018 and 2017 , for financial instruments measured on a recurring basis and classified as Level 3. The classification of an item as Level 3 is based on the significance of the unobservable inputs to the overall fair value measurement. However, Level 3 measurements may also include observable components of value that can be validated externally. Accordingly, the gains and losses in the table below include changes in fair value due in part to observable factors that are part of the valuation methodology. Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Opening balance $ 11 $ (1 ) $ 3,167 $ 24 $ 38 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — (5 ) — — — Total gains/losses for the period: Included in earnings 1 6 (1 ) (2 ) — Included in OCI — — (28 ) 11 — Purchases/originations — — 193 — — Sales — — — (33 ) — Repayments — — — — (1 ) Settlements — — (101 ) — — Closing balance $ 12 $ — $ 3,230 $ — $ 37 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ 1 $ — $ — $ — $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Opening balance $ 14 $ (2 ) $ 2,798 $ 76 $ 48 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — — — — — Total gains/losses for the period: Included in earnings (1 ) 5 (1 ) — — Included in OCI — — 20 3 — Purchases/originations — — 133 — — Sales — — (19 ) — Repayments — — — — (4 ) Settlements — — (82 ) (1 ) — Closing balance $ 13 $ 3 $ 2,868 $ 59 $ 44 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ 5 $ 20 $ 1 $ — (1) Transfers out of Level 3 represent the settlement value of the derivative instruments (i.e. interest rate lock agreements) that is transferred to loans held for sale, which is classified as Level 2. The tables below summarize the classification of gains and losses due to changes in fair value, recorded in earnings for Level 3 assets and liabilities for the three-month periods ended March 31, 2018 and 2017 : Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ 1 $ 6 $ — $ — $ — Securities gains (losses) — — — (2 ) — Other expense — — (1 ) — — Total $ 1 $ 6 $ (1 ) $ (2 ) $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ (1 ) $ 5 $ — $ — $ — Securities gains (losses) — — (1 ) — — Total $ (1 ) $ 5 $ (1 ) $ — $ — Assets and liabilities under the fair value option The following tables present the fair value and aggregate principal balance of certain assets and liabilities under the fair value option: March 31, 2018 (dollar amounts in millions) Total Loans Loans that are 90 or more days past due Assets Fair value carrying amount Aggregate unpaid principal Difference Fair value carrying amount Aggregate unpaid principal Difference Loans held for sale $ 426 $ 416 $ 10 $ 1 $ 1 $ — Loans held for investment 86 94 (8 ) 8 9 (1 ) December 31, 2017 (dollar amounts in millions) Total Loans Loans that are 90 or more days past due Assets Fair value carrying amount Aggregate unpaid principal Difference Fair value carrying amount Aggregate unpaid principal Difference Loans held for sale $ 413 $ 400 $ 13 $ 1 $ 1 $ — Loans held for investment 93 102 (9 ) 10 11 (1 ) The following tables present the net gains (losses) from fair value changes for the three-month periods ended March 31, 2018 and 2017 . Net gains (losses) from fair value changes (dollar amounts in millions) Three Months Ended Assets 2018 2017 Loans held for sale $ (2 ) $ 9 Loans held for investment — — Assets and Liabilities measured at fair value on a nonrecurring basis Certain assets and liabilities may be required to be measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition. These assets and liabilities are not measured at fair value on an ongoing basis; however, they are subject to fair value adjustments in certain circumstances, such as when there is evidence of impairment. For the three months ended March 31, 2018 , assets measured at fair value on a nonrecurring basis were as follows: Fair Value Measurements Using (dollar amounts in millions) Fair Value Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total Impaired loans 58 — — 58 — Other real estate owned 30 — — 30 — MSRs accounted for under the amortization method are subject to nonrecurring fair value measurement when the fair value is lower than the carrying amount. Periodically, Huntington records nonrecurring adjustments of collateral-dependent loans measured for impairment when establishing the ALLL. Such amounts are generally based on the fair value of the underlying collateral supporting the loan. Appraisals are generally obtained to support the fair value of the collateral and incorporate measures such as recent sales prices for comparable properties and cost of construction. In cases where the carrying value exceeds the fair value of the collateral less cost to sell, an impairment charge is recognized. Other real estate owned properties are included in accrued income and other assets and valued based on appraisals and third-party price opinions. Significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis The table below presents quantitative information about the significant unobservable inputs for assets and liabilities measured at fair value on a recurring and nonrecurring basis at March 31, 2018 and December 31, 2017 : Quantitative Information about Level 3 Fair Value Measurements at March 31, 2018 (dollar amounts in millions) Fair Value Valuation Technique Significant Unobservable Input Range (Weighted Average) Measured at fair value on a recurring basis: MSRs $ 12 Discounted cash flow Constant prepayment rate 6% - 31% (9%) Spread over forward interest rate 5% - 11% (8%) Derivative assets 6 Consensus Pricing Net market price -5% - 20% (2%) Estimated Pull through % 0% - 100% (85%) Derivative liabilities 6 Discounted cash flow Estimated conversion factor 165% Estimated growth rate of Visa Class A shares 7% Discount rate 3% Timing of the resolution of the litigation 3/31/2018 - 06/30/2020 Municipal securities 3,230 Discounted cash flow Discount rate 0% - 9% (3%) Cumulative default 0% - 64% (3%) Loss given default 5% - 90% (25%) Loans held for investment 37 Discounted cash flow Discount rate 7% - 18% (8%) Constant prepayment rate 2% - 22% (8%) Measured at fair value on a nonrecurring basis: Impaired loans 58 Appraisal value NA NA Other real estate owned 30 Appraisal value NA NA Quantitative Information about Level 3 Fair Value Measurements at December 31, 2017 (dollar amounts in millions) Fair Value Valuation Technique Significant Unobservable Input Range (Weighted Average) Measured at fair value on a recurring basis: MSRs $ 11 Discounted cash flow Constant prepayment rate 8% - 33% (12%) Spread over forward interest rate 8% - 10% (8%) Derivative assets 6 Consensus Pricing Net market price -5% - 20% (2%) Estimated Pull through % 3% - 100% (75%) Derivative liabilities 5 Discounted cash flow Estimated conversion factor 165% Estimated growth rate of Visa Class A shares 7% Discount rate 3% Timing of the resolution of the litigation 12/31/2017 - 06/30/2020 Municipal securities 3,167 Discounted cash flow Discount rate 0% - 10% (4%) Cumulative default 0% - 64% (3%) Loss given default 5% - 90% (24%) Asset-backed securities 24 Discounted cash flow Discount rate 7% - 7% (7%) Cumulative prepayment rate 0% - 72% (7%) Cumulative default 3% - 53% (7%) Loss given default 90% - 100% (98%) Cure given deferral 50% - 50% (50%) Loans held for investment 38 Discounted cash flow Discount rate 7% - 18% (8%) Constant prepayment rate 2% - 22% (9%) Measured at fair value on a nonrecurring basis: MSRs 190 Discounted cash flow Constant prepayment rate 6% - 21% (8%) Spread over forward interest rate 2% - 20% (10%) Impaired loans 36 Appraisal value NA NA Other real estate owned 33 Appraisal value NA NA The following provides a general description of the impact of a change in an unobservable input on the fair value measurement and the interrelationship between unobservable inputs, where relevant/significant. Interrelationships may also exist between observable and unobservable inputs. Such relationships have not been included in the discussion below. A significant change in the unobservable inputs may result in a significant change in the ending fair value measurement of Level 3 instruments. In general, prepayment rates increase when market interest rates decline and decrease when market interest rates rise and higher prepayment rates generally resulting in lower fair values for MSR assets and asset-backed securities. Credit loss estimates, such as probability of default, constant default, cumulative default, loss given default, cure given deferral, and loss severity, are driven by the ability of the borrowers to pay their loans and the value of the underlying collateral and are impacted by changes in macroeconomic conditions, typically increasing when economic conditions worsen and decreasing when conditions improve. An increase in the estimated prepayment rate typically results in a decrease in estimated credit losses and vice versa. Higher credit loss estimates generally result in lower fair values. Credit spreads generally increase when liquidity risks and market volatility increase and decrease when liquidity conditions and market volatility improve. Discount rates and spread over forward interest rate swap rates typically increase when market interest rates increase and/or credit and liquidity risks increase and decrease when market interest rates decline and/or credit and liquidity conditions improve. Higher discount rates and credit spreads generally result in lower fair market values. Net market price and pull through percentages generally increase when market interest rates increase and decline when market interest rates decline. Higher net market price and pull through percentages generally result in higher fair values. Fair values of financial instruments The following table provides the carrying amounts and estimated fair values of Huntington’s financial instruments at March 31, 2018 and December 31, 2017 : March 31, 2018 (dollar amounts in millions) Amortized Cost Lower of Cost or Market Fair Value or Fair Value Option Total Carrying Amount Estimated Fair Value Financial Assets Cash and short-term assets 1,115 — — 1,115 1,115 Trading account securities — — 85 85 85 Available-for-sale securities — — 14,607 14,607 14,607 Held-to-maturity securities 8,789 — — 8,789 8,550 Other securities 581 — 21 602 602 Loans held for sale — 80 426 506 510 Net loans and direct financing leases (1) 70,356 — 86 70,442 69,820 Derivatives — — 87 87 87 Financial Liabilities Deposits 79,471 — — 79,471 79,425 Short-term borrowings 2,854 — — 2,854 2,854 Long-term debt 8,618 — — 8,618 8,771 Derivatives — — 157 157 157 (1) Includes collateral-dependent loans measured for impairment. December 31, 2017 (dollar amounts in millions) Amortized Cost Lower of Cost or Market Fair Value or Fair Value Option Total Carrying Amount Estimated Fair Value Financial Assets Cash and short-term assets 1,567 — — $ 1,567 $ 1,567 Trading account securities — — 86 86 86 Available-for-sale securities — — 14,869 14,869 14,869 Held-to-maturity securities 9,091 — — 9,091 8,971 Other securities 581 — 19 600 600 Loans held for sale — 75 413 488 491 Net loans and direct financing leases (1) 69,333 — 93 69,426 69,146 Derivatives — — 132 132 132 Financial Liabilities Deposits 77,041 — — 77,041 77,010 Short-term borrowings 5,056 — — 5,056 5,056 Long-term debt 9,206 — — 9,206 9,402 Derivatives — — 86 86 86 (1) Includes collateral-dependent loans measured for impairment. The following table presents the level in the fair value hierarchy for the estimated fair values at March 31, 2018 and December 31, 2017 : Estimated Fair Value Measurements at Reporting Date Using March 31, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 82 $ 3 $ — $ 85 Available-for-sale securities 5 11,372 3,230 14,607 Held-to-maturity securities — 8,550 — 8,550 Other securities 21 — — 21 Loans held for sale — 426 84 510 Net loans and direct financing leases — — 69,820 69,820 Financial Liabilities Deposits — 74,573 4,852 79,425 Short-term borrowings 1 — 2,853 2,854 Long-term debt — 8,299 472 8,771 Estimated Fair Value Measurements at Reporting Date Using December 31, 2017 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 83 $ 3 $ — $ 86 Available-for-sale securities 5 11,673 3,191 14,869 Held-to-maturity securities — 8,971 — 8,971 Other securities 19 — — 19 Loans held for sale — 413 78 491 Net loans and direct financing leases — — 69,146 69,146 Financial Liabilities Deposits — 73,975 3,035 77,010 Short-term borrowings — — 5,056 5,056 Long-term debt — 8,944 458 9,402 The short-term nature of certain assets and liabilities result in their carrying value approximating fair value. These include trading account securities, customers’ acceptance liabilities, short-term borrowings, bank acceptances outstanding, FHLB advances, and cash and short-term assets, which include cash and due from banks, interest-bearing deposits in banks, and federal funds sold and securities purchased under resale agreements. Loan commitments and letters-of-credit generally have short-term, variable-rate features and contain clauses that limit Huntington’s exposure to changes in customer credit quality. Accordingly, their carrying values, which are immaterial at the respective balance sheet dates, are reasonable estimates of fair value. Certain assets, the most significant being operating lease assets, bank owned life insurance, and premises and equipment, do not meet the definition of a financial instrument and are excluded from this disclosure. Similarly, mortgage and nonmortgage servicing rights, deposit base, and other customer relationship intangibles are not considered financial instruments and are not included above. Accordingly, this fair value information is not intended to, and does not, represent Huntington’s underlying value. Many of the assets and liabilities subject to the disclosure requirements are not actively traded, requiring fair values to be estimated by Management. These estimations necessarily involve the use of judgment about a wide variety of factors, including but not limited to, relevancy of market prices of comparable instruments, expected future cash flows, and appropriate discount rates.

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	DERIVATIVE FINANCIAL INSTRUMENTS Derivative financial instruments are recorded in the Unaudited Condensed Consolidated Balance Sheets as either an asset or a liability (in accrued income and other assets or accrued expenses and other liabilities, respectively) and measured at fair value. The following table presents the fair values of all derivative instruments included in the Unaudited Condensed Consolidated Balance Sheets at March 31, 2018 and December 31, 2017 . Amounts in the table below are presented gross without the impact of any net collateral arrangements. March 31, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Derivatives designated as Hedging Instruments Interest rate contracts $ 15 $ 191 $ 22 $ 121 Derivatives not designated as Hedging Instruments Interest rate contracts (1) 228 138 187 100 Foreign exchange contracts 20 22 18 18 Commodities contracts 89 83 92 87 Equity contracts 4 5 3 5 Total Contracts $ 356 $ 439 $ 322 $ 331 (1) Includes derivative assets and liabilities used in mortgage banking activities. The following table presents the amount of gain or loss recognized in income for derivatives not designated as hedging instruments under ASC Subtopic 815-10 in the Unaudited Condensed Consolidated Income Statement for the three months ended March 31, 2018 . Location of Gain or (Loss) Recognized in Income on Derivative Amount of Gain or (Loss) Recognized in Income on Derivative (dollar amounts in millions) Three Months Ended March 31, 2018 Interest rate contracts: Customer Capital markets fees $ 7 MSR Mortgage banking income (8 ) Foreign exchange contracts Capital markets fees 6 Commodities contracts Capital markets fees 2 Equity contracts Other noninterest expense (1 ) Total $ 6 Derivatives used in asset and liability management activities Huntington engages in balance sheet hedging activity, principally for asset and liability management purposes, to convert fixed rate assets or liabilities into floating rate, or vice versa. Balance sheet hedging activity is arranged to receive hedge accounting treatment and is classified as either fair value or cash flow hedges. Fair value hedges are purchased to convert subordinated and other long-term debt from fixed-rate obligations to floating rate. Cash flow hedges are also used to convert floating rate loans into fixed rate loans. The following table presents the gross notional values of derivatives used in Huntington’s asset and liability management activities at March 31, 2018 and December 31, 2017 , identified by the underlying interest rate-sensitive instruments. March 31, 2018 (dollar amounts in millions) Fair Value Hedges Cash Flow Hedges Total Instruments associated with: Investment securities — 12 $ 12 Subordinated notes 950 — 950 Long-term debt 6,890 — 6,890 Total notional value at March 31, 2018 $ 7,840 $ 12 $ 7,852 December 31, 2017 (dollar amounts in millions) Fair Value Hedges Cash Flow Hedges Total Instruments associated with: Subordinated notes 950 — 950 Long-term debt 7,425 — 7,425 Total notional value at December 31, 2017 $ 8,375 $ — $ 8,375 The following table presents additional information about the interest rate swaps used in Huntington’s asset and liability management activities at March 31, 2018 and December 31, 2017 . March 31, 2018 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Asset conversion swaps Receive fixed—generic $ 12 2.0 $ — 2.20 % 1.78 % Liability conversion swaps Receive fixed—generic 7,840 2.4 (176 ) 1.57 1.88 Total swap portfolio at March 31, 2018 $ 7,852 2.4 $ (176 ) December 31, 2017 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Liability conversion swaps Receive fixed—generic 8,375 2.5 (99 ) 1.56 1.44 Total swap portfolio at December 31, 2017 $ 8,375 2.5 $ (99 ) These derivative financial instruments are entered into to manage the interest rate risk of assets and liabilities. Consequently, net amounts receivable or payable on contracts hedging either interest earning assets or interest-bearing liabilities are an adjustment to either interest income or interest expense. The net amounts resulted in an increase to net interest income of $1 million and $10 million for the three-month periods ended March 31, 2018 , and 2017 , respectively. Fair Value Hedges The changes in fair value of the fair value hedges are recorded through earnings and offset against changes in the fair value of the hedged item. The following table presents the change in fair value for derivatives designated as fair value hedges as well as the offsetting change in fair value on the hedged item for the three-month periods ended March 31, 2018 and 2017 . Three Months Ended (dollar amounts in millions) 2018 2017 Interest rate contracts Change in fair value of interest rate swaps hedging subordinated notes (1) (17 ) (5 ) Change in fair value of hedged subordinated notes (1) 18 5 Change in fair value of interest rate swaps hedging other long-term debt (1) (51 ) (10 ) Change in fair value of hedged other long-term debt (1) 53 9 (1) Recognized in Interest expense—subordinated notes and other long-term debt in the Unaudited Condensed Consolidated Statements of Income. As of March 31, 2018 , the following amounts were recorded on the balance sheet related to cumulative basis adjustments for fair value hedges. Carrying Amount of the Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment To Hedged Liabilities (dollar amounts in millions) March 31, 2018 March 31, 2018 Long-term debt $ 7,709 $ (186 ) Total $ 7,709 $ (186 ) The cumulative amount of fair value hedging adjustments remaining for any hedged assets and liabilities for which hedge accounting has been discontinued is less than $1 million at March 31, 2018. Cash Flow Hedges Changes in the fair value of derivatives designated as cash flow hedges will not be included in current earnings but are reported as a component of OCI in the Unaudited Condensed Consolidated statements of Changes in Shareholders' Equity. These changes in fair value will be included in earnings of future periods when earnings are also affected by the changes in the hedged cash flows. The following table presents the gains and (losses) recognized in OCI and the location in the Unaudited Condensed Consolidated Statements of Income of gains and (losses) reclassified from OCI into earnings for derivatives designated as effective cash flow hedges for the three-month periods ended March 31, 2018 and 2017 . Derivatives in cash flow hedging relationships Amount of gain or (loss) recognized in OCI on derivatives (effective portion) (after-tax) Location of gain or (loss) reclassified from accumulated OCI into earnings (effective portion) Amount of (gain) or loss reclassified from accumulated OCI into earnings (effective portion) Three Months Ended March 31, Three Months Ended March 31, (dollar amounts in millions) 2018 2017 2018 2017 Interest rate contracts Loans $ — $ (1 ) Interest and fee income - loans and leases $ — $ 1 Investment securities — — Noninterest income - other income — — Total $ — $ (1 ) $ — $ 1 Derivatives used in mortgage banking activities Mortgage loan origination hedging activity Hunting ton’s mortgage origination hedging activity is related to the hedging of the mortgage pricing commitments to customers and the secondary sale to third parties. The value of a newly originated mortgage is not firm until the interest rate is committed or locked. The interest rate lock commitments are derivative positions offset by forward commitments to sell loans. Huntington uses two types of mortgage-backed securities in its forward commitments to sell loans. The first type of forward commitment is a “To Be Announced” (or TBA), the second is a “Specified Pool” mortgage-backed security. Huntington uses these derivatives to hedge the value of mortgage-backed securities until they are sold. The following table summarizes the derivative assets and liabilities used in mortgage banking activities: Derivatives used in mortgage banking activities March 31, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Interest rate lock agreements $ 6 $ 1 $ 6 $ — Forward trades and options 2 2 1 — Total derivatives used in mortgage banking activities $ 8 $ 3 $ 7 $ — MSR hedging activity Huntington’s MSR economic hedging activity uses securities and derivatives to manage the value of the MSR asset and to mitigate the various types of risk inherent in the MSR asset, including risks related to duration, basis, convexity, volatility, and yield curve. The hedging instruments include forward commitments, interest rate swaps, and options on interest rate swaps. The total notional value of these derivative financial instruments at March 31, 2018 and December 31, 2017 , was $125 million and $188 million , respectively. The total notional amount at March 31, 2018 corresponds to trading assets with a fair value of less than $1 million and no trading liabilities. Net trading gains and (losses) related to MSR hedging for the three-month periods ended March 31, 2018 and 2017 , were $(8) million and $(1) million , respectively. These amounts are included in mortgage banking income in the Unaudited Condensed Consolidated Statements of Income. Derivatives used in customer related activities Various derivative financial instruments are offered to enable customers to meet their financing and investing objectives and for their risk management purposes. Derivative financial instruments used in trading activities consist of commodity, interest rate, and foreign exchange contracts. Huntington may enter into offsetting third-party contracts with approved, reputable counterparties with substantially matching terms and currencies in order to economically hedge significant exposure related to derivatives used in trading activities. The interest rate risk of customer derivatives is mitigated by entering into similar derivatives having offsetting terms with other counterparties. The credit risk to these customers is evaluated and included in the calculation of fair value. Foreign currency derivatives help the customer hedge risk and reduce exposure to fluctuations in exchange rates. Transactions are primarily in liquid currencies with Canadian dollars and Euros comprising a majority of all transactions. Commodity derivatives help the customer hedge risk and reduce exposure to fluctuations in the price of various commodities. Hedging of energy-related products and base metals comprise the majority of all transactions. The net fair values of these derivative financial instruments, for which the gross amounts are included in accrued income and other assets or accrued expenses and other liabilities at both March 31, 2018 and December 31, 2017 , were $90 million and $88 million , respectively. The total notional values of derivative financial instruments used by Huntington on behalf of customers, including offsetting derivatives, were $22.7 billion and $22.0 billion at March 31, 2018 and December 31, 2017 , respectively. Huntington’s credit risk from interest rate swaps used for trading purposes was $53 million and $119 million at the same dates, respectively. Visa ® -related Swap In connection with the sale of Huntington’s Class B Visa ® shares, Huntington entered into a swap agreement with the purchaser of the shares. The swap agreement adjusts for dilution in the conversion ratio of Class B shares resulting from changes in the Visa ® litigation. In connection with the FirstMerit acquisition, Huntington acquired an additional Visa ® related swap agreement. At March 31, 2018 , the combined fair value of the swap liabilities of $5 million is an estimate of the exposure liability based upon Huntington’s assessment of the potential Visa ® litigation losses and timing of the litigation settlement. Financial assets and liabilities that are offset in the Unaudited Condensed Consolidated Balance Sheets Huntington records derivatives at fair value as further described in Note 13 . Derivative balances are presented on a net basis taking into consideration the effects of legally enforceable master netting agreements. Additionally, collateral exchanged with counterparties is also netted against the applicable derivative fair values. Huntington enters into derivative transactions with two primary groups: broker-dealers and banks, and Huntington’s customers. Different methods are utilized for managing counterparty credit exposure and credit risk for each of these groups. Huntington enters into transactions with broker-dealers and banks for various risk management purposes. These types of transactions generally are high dollar volume. Huntington enters into bilateral collateral and master netting agreements with these counterparties, and routinely exchanges cash and high quality securities collateral. Huntington enters into transactions with customers to meet their financing, investing, payment and risk management needs. These types of transactions generally are low dollar volume. Huntington enters into master netting agreements with customer counterparties; however, collateral is generally not exchanged with customer counterparties. At March 31, 2018 and December 31, 2017 , aggregate credit risk associated with these derivatives, net of collateral that has been pledged by the counterparty, was $27 million and $30 million , respectively. The credit risk associated with interest rate swaps is calculated after considering master netting agreements with broker-dealers and banks. At March 31, 2018 , Huntington pledged $95 million of investment securities and cash collateral to counterparties, while other counterparties pledged $74 million of investment securities and cash collateral to Huntington to satisfy collateral netting agreements. In the event of credit downgrades, Huntington would not be required to provide additional collateral. The following tables present the gross amounts of these assets and liabilities with any offsets to arrive at the net amounts recognized in the Unaudited Condensed Consolidated Balance Sheets at March 31, 2018 and December 31, 2017 . Offsetting of Financial Assets and Derivative Assets Gross amounts Net amounts of Gross amounts not offset in the condensed consolidated balance sheets (dollar amounts in millions) Gross amounts of recognized assets Financial instruments Cash collateral received Net amount March 31, 2018 Derivatives $ 356 $ (269 ) $ 87 $ (2 ) $ (11 ) $ 74 December 31, 2017 Derivatives 322 (190 ) 132 (11 ) (18 ) 103 Offsetting of Financial Liabilities and Derivative Liabilities Gross amounts offset in the condensed consolidated balance sheets Net amounts of liabilities presented in the condensed consolidated balance sheets Gross amounts not offset in the condensed consolidated balance sheets (dollar amounts in millions) Gross amounts of recognized liabilities Financial instruments Cash collateral delivered Net amount March 31, 2018 Derivatives $ 439 $ (282 ) $ 157 $ — $ (21 ) $ 136 December 31, 2017 Derivatives 331 (245 ) 86 — (21 ) 65

VIEs

VIEs	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VIEs	VIEs Unconsolidated VIEs The following tables provide a summary of the assets and liabilities included in Huntington’s Unaudited Condensed Consolidated Financial Statements, as well as the maximum exposure to losses, associated with its interests related to unconsolidated VIEs for which Huntington holds an interest, but is not the primary beneficiary, to the VIE at March 31, 2018 , and December 31, 2017 : March 31, 2018 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 6 $ 1 $ 6 2015-1 Automobile Trust 1 — 1 Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 634 320 634 Other Investments 122 57 122 Total $ 777 $ 630 $ 763 December 31, 2017 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 7 $ — $ 7 2015-1 Automobile Trust 1 — 1 Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 636 335 636 Other Investments 117 53 117 Total $ 775 $ 640 $ 761 Automobile Securitizations The following table provides a summary of automobile transfers to trusts in separate securitization transactions. (dollar amounts in millions) Year Amount Transferred 2016-1 Automobile Trust 2016 $ 1,500 2015-1 Automobile Trust 2015 750 The securitizations and the resulting sale of all underlying securities qualified for sale accounting. Huntington has concluded that it is not the primary beneficiary of these trusts because it has neither the obligation to absorb losses of the entities that could potentially be significant to the VIEs nor the right to receive benefits from the entities that could potentially be significant to the VIEs. Huntington is not required and does not currently intend to provide any additional financial support to the trusts. Investors and creditors only have recourse to the assets held by the trusts. The interest Huntington holds in the VIEs relates to servicing rights which are included within accrued income and other assets of Huntington’s Unaudited Consolidated Balance Sheets. The maximum exposure to loss is equal to the carrying value of the servicing asset. See Note 7 for more information. Trust-Preferred Securities Huntington has certain wholly-owned trusts whose assets, liabilities, equity, income, and expenses are not included within Huntington’s Unaudited Condensed Consolidated Financial Statements. These trusts have been formed for the sole purpose of issuing trust-preferred securities, from which the proceeds are then invested in Huntington junior subordinated debentures, which are reflected in Huntington’s Unaudited Condensed Consolidated Balance Sheet as long-term debt. The trust securities are the obligations of the trusts, and as such, are not consolidated within Huntington’s Unaudited Condensed Consolidated Financial Statements. A list of trust preferred securities outstanding at March 31, 2018 follows: (dollar amounts in millions) Rate Principal amount of subordinated note/ debenture issued to trust (1) Investment in unconsolidated subsidiary Huntington Capital I 3.01 % (2) $ 70 $ 6 Huntington Capital II 2.94 (3) 32 3 Sky Financial Capital Trust III 3.71 (4) 72 2 Sky Financial Capital Trust IV 3.71 (4) 74 2 Camco Financial Trust 3.64 (5) 4 1 Total $ 252 $ 14 (1) Represents the principal amount of debentures issued to each trust, including unamortized original issue discount. (2) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 0.70% . (3) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 0.625% . (4) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 1.40% . (5) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 1.33% . Each issue of the junior subordinated debentures has an interest rate equal to the corresponding trust securities distribution rate. Huntington has the right to defer payment of interest on the debentures at any time, or from time-to-time for a period not exceeding five years provided that no extension period may extend beyond the stated maturity of the related debentures. During any such extension period, distributions to the trust securities will also be deferred and Huntington’s ability to pay dividends on its common stock will be restricted. Periodic cash payments and payments upon liquidation or redemption with respect to trust securities are guaranteed by Huntington to the extent of funds held by the trusts. The guarantee ranks subordinate and junior in right of payment to all indebtedness of the Company to the same extent as the junior subordinated debt. The guarantee does not place a limitation on the amount of additional indebtedness that may be incurred by Huntington. Affordable Housing Tax Credit Partnerships Huntington makes certain equity investments in various limited partnerships that sponsor affordable housing projects utilizing the Low Income Housing Tax Credit (LIHTC) pursuant to Section 42 of the Internal Revenue Code. The purpose of these investments is to achieve a satisfactory return on capital, to facilitate the sale of additional affordable housing product offerings, and to assist in achieving goals associated with the Community Reinvestment Act. The primary activities of the limited partnerships include the identification, development, and operation of multi-family housing that is leased to qualifying residential tenants. Generally, these types of investments are funded through a combination of debt and equity. Huntington uses the proportional amortization method to account for a majority of its investments in these entities. These investments are included in accrued income and other assets. Investments that do not meet the requirements of the proportional amortization method are recognized using the equity method. Investment losses related to these investments are included in noninterest income in the Unaudited Condensed Consolidated Statements of Income. The following table presents the balances of Huntington’s affordable housing tax credit investments and related unfunded commitments at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) March 31, December 31, Affordable housing tax credit investments $ 1,013 $ 996 Less: amortization (379 ) (360 ) Net affordable housing tax credit investments $ 634 $ 636 Unfunded commitments $ 320 $ 335 The following table presents other information relating to Huntington’s affordable housing tax credit investments for the three-month periods ended March 31, 2018 and 2017 . Three Months Ended (dollar amounts in millions) 2018 2017 Tax credits and other tax benefits recognized $ 23 $ 23 Proportional amortization method Tax credit amortization expense included in provision for income taxes 19 17 Huntington recognized immaterial impairment losses for the three-month periods ended March 31, 2018 and 2017 . The impairment losses recognized related to the fair value of the tax credit investments that were less than carrying value. Other Investments Other investments determined to be VIE's include investments in New Market Tax Credit Investments, Historic Tax Credit Investments, Small Business Investment Companies, Rural Business Investment Companies, certain equity method investments and other miscellaneous investments.

COMMITMENTS AND CONTINGENT LIAB

COMMITMENTS AND CONTINGENT LIABILITIES	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENT LIABILITIES	COMMITMENTS AND CONTINGENT LIABILITIES Commitments to extend credit In the ordinary course of business, Huntington makes various commitments to extend credit that are not reflected in the Unaudited Condensed Consolidated Financial Statements. The contract amounts of these financial agreements at March 31, 2018 and December 31, 2017 , were as follows: (dollar amounts in millions) March 31, December 31, Contract amount represents credit risk Commitments to extend credit: Commercial $ 16,265 $ 16,219 Consumer 14,353 13,384 Commercial real estate 1,323 1,366 Standby letters of credit 583 510 Commercial letters-of-credit 17 21 Commitments to extend credit generally have fixed expiration dates, are variable-rate, and contain clauses that permit Huntington to terminate or otherwise renegotiate the contracts in the event of a significant deterioration in the customer’s credit quality. These arrangements normally require the payment of a fee by the customer, the pricing of which is based on prevailing market conditions, credit quality, probability of funding, and other relevant factors. Since many of these commitments are expected to expire without being drawn upon, the contract amounts are not necessarily indicative of future cash requirements. The interest rate risk arising from these financial instruments is insignificant as a result of their predominantly short-term, variable-rate nature. Standby letters-of-credit are conditional commitments issued to guarantee the performance of a customer to a third party. These guarantees are primarily issued to support public and private borrowing arrangements, including commercial paper, bond financing, and similar transactions. Most of these arrangements mature within two years . The carrying amount of deferred revenue associated with these guarantees was $11 million and $10 million at March 31, 2018 and December 31, 2017 , respectively. Commercial letters-of-credit represent short-term, self-liquidating instruments that facilitate customer trade transactions and generally have maturities of no longer than 90 days . The goods or cargo being traded normally secures these instruments. Commitments to sell loans Activity related to our mortgage origination activity supports the hedging of the mortgage pricing commitments to customers and the secondary sale to third parties. At March 31, 2018 and December 31, 2017 , Huntington had commitments to sell residential real estate loans of $0.8 billion and $0.7 billion , respectively. These contracts mature in less than one year . Litigation and Regulatory Matters In the ordinary course of business, Huntington is routinely a defendant in or party to pending and threatened legal and regulatory actions and proceedings. In view of the inherent difficulty of predicting the outcome of such matters, particularly where the claimants seek very large or indeterminate damages or where the matters present novel legal theories or involve a large number of parties, Huntington generally cannot predict what the eventual outcome of the pending matters will be, what the timing of the ultimate resolution of these matters will be, or what the eventual loss, fines or penalties related to each matter may be. Huntington establishes an accrued liability when those matters present loss contingencies that are both probable and estimable. In such cases, there may be an exposure to loss in excess of any amounts accrued. Huntington thereafter continues to monitor the matter for further developments that could affect the amount of the accrued liability that has been previously established. For certain matters, Huntington is able to estimate a range of possible loss. In cases in which Huntington possesses information to estimate a range of possible loss, that estimate is aggregated and disclosed below. There may be other matters for which a loss is probable or reasonably possible but such an estimate of the range of possible loss may not be possible. For those matters where an estimate of the range of possible loss is possible, management currently estimates the aggregate range of possible loss is $0 to $30 million at March 31, 2018 in excess of the accrued liability (if any) related to those matters. This estimated range of possible loss is based upon currently available information and is subject to significant judgment and a variety of assumptions, and known and unknown uncertainties. The matters underlying the estimated range will change from time to time, and actual results may vary significantly from the current estimate. The estimated range of possible loss does not represent Huntington’s maximum loss exposure. Information is provided below regarding the nature of all of these contingencies and, where specified, the amount of the claim associated with these loss contingencies. Based on current knowledge, management does not believe that loss contingencies arising from pending matters, including the matters described herein, will have a material adverse effect on the consolidated financial position of Huntington. Further, management believes that amounts previously accrued are adequate to address Huntington’s contingent liabilities. However, in light of the inherent uncertainties involved in these matters, some of which are beyond Huntington’s control, and the large or indeterminate damages sought in some of these matters, an adverse outcome in one or more of these matters could be material to Huntington’s results of operations for any particular reporting period. Meoli v. The Huntington National Bank (Cyberco Litigation). The parties reached an agreement in principle on January 31, 2018 to settle the matter. The Bankruptcy Court entered an order approving the settlement on April 16, 2018, which order will become final on April 30, 2018. Powell v. The Huntington National Bank. During the 2018 first quarter, the parties settled for a sum that was both immaterial and fully accrued.

SEGMENT REPORTING

SEGMENT REPORTING	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
SEGMENT REPORTING	SEGMENT REPORTING Huntington's business segments are based on our internally-aligned segment leadership structure, which is how management monitors results and assesses performance. The Company has four major business segments: Consumer and Business Banking , Commercial Banking , Vehicle Finance , Regional Banking and The Huntington Private Client Group (RBHPCG) . The Treasury / Other function includes technology and operations, other unallocated assets, liabilities, revenue, and expense. Business segment results are determined based upon Huntington's management reporting system, which assigns balance sheet and income statement items to each of the business segments. The process is designed around the organizational and management structure and, accordingly, the results derived are not necessarily comparable with similar information published by other financial institutions. Additionally, because of the interrelationships of the various segments, the information presented is not indicative of how the segments would perform if they operated as independent entities. Revenue is recorded in the business segment responsible for the related product or service. Fee sharing is recorded to allocate portions of such revenue to other business segments involved in selling to, or providing service to customers. Results of operations for the business segments reflect these fee-sharing allocations. The management process that develops the business segment reporting utilizes various estimates and allocation methodologies to measure the performance of the business segments. Expenses are allocated to business segments using a two-phase approach. The first phase consists of measuring and assigning unit costs (activity-based costs) to activities related to product origination and servicing. These activity-based costs are then extended, based on volumes, with the resulting amount allocated to business segments that own the related products. The second phase consists of the allocation of overhead costs to all four business segments from Treasury / Other . Huntington utilizes a full-allocation methodology, where all Treasury / Other expenses, except reported Significant Items, and a small amount of other residual unallocated expenses, are allocated to the four business segments. The management policies and processes utilized in compiling segment financial information are highly subjective and, unlike financial accounting, are not based on authoritative guidance similar to GAAP. As a result, reported segment results are not necessarily comparable with similar information reported by other financial institutions. Furthermore, changes in management structure or allocation methodologies and procedures result in changes in reported segment financial data. Accordingly, certain amounts have been reclassified to conform to the current period presentation. Huntington uses an active and centralized FTP methodology to attribute appropriate net interest income to the business segments. The intent of the FTP methodology is to transfer interest rate risk from the business segments by providing matched duration funding of assets and liabilities. The result is to centralize the financial impact, management, and reporting of interest rate risk in the Treasury / Other function where it can be centrally monitored and managed. The Treasury / Other function charges (credits) an internal cost of funds for assets held in (or pays for funding provided by) each business segment. The FTP rate is based on prevailing market interest rates for comparable duration assets (or liabilities). A new methodology for establishing FTP rates was adopted in 2017, therefore prior period amounts have been restated to reflect the new methodology. Consumer and Business Banking - The Consumer and Business Banking segment, including Home Lending, provides a wide array of financial products and services to consumer and small business customers including but not limited to checking accounts, savings accounts, money market accounts, certificates of deposit, mortgage loans, consumer loans, credit cards, and small business loans and investment products. Other financial services available to consumer and small business customers include insurance, interest rate risk protection, foreign exchange, and treasury management. Business Banking is defined as serving companies with revenues up to $20 million . Home Lending supports origination and servicing of consumer loans and mortgages for customers who are generally located in our primary banking markets across all segments. Commercial Banking - Through a relationship banking model, this segment provides a wide array of products and services to the middle market, large corporate, real estate and government public sector customers located primarily within our geographic footprint. The segment is divided into six business units: Middle Market, Specialty Banking, Asset Finance, Capital Markets/Institutional Corporate Banking, Commercial Real Estate and Treasury Management. Vehicle Finance - Our products and services include providing financing to consumers for the purchase of automobiles, light-duty trucks, recreational vehicles and marine craft at franchised and other select dealerships, and providing financing to franchised dealerships for the acquisition of new and used inventory. Products and services are delivered through highly specialized relationship-focused bankers and product partners. Regional Banking and The Huntington Private Client Group - The core business of The Huntington Private Client Group is The Huntington Private Bank, which consists of Private Banking, Wealth & Investment Management, and Retirement Plan Services. The Huntington Private Bank provides high net-worth customers with deposit, lending (including specialized lending options), and banking services. The Huntington Private Bank also delivers wealth management and legacy planning through investment and portfolio management, fiduciary administration, and trust services. This group also provides retirement plan services to corporate businesses. The Huntington Private Client Group provides corporate trust services and institutional and mutual fund custody services. Listed in the table below is certain operating basis financial information reconciled to Huntington’s March 31, 2018 , December 31, 2017 , and March 31, 2017 , reported results by business segment. Three Months Ended March 31, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 395 $ 220 $ 99 $ 45 $ 11 $ 770 Provision (benefit) for credit losses 31 21 14 — — 66 Noninterest income 174 69 3 51 17 314 Noninterest expense 412 120 35 58 8 633 Provision (benefit) for income taxes 26 31 11 8 (17 ) 59 Net income (loss) $ 100 $ 117 $ 42 $ 30 $ 37 $ 326 2017 Net interest income $ 375 $ 228 $ 104 $ 45 $ (22 ) $ 730 Provision (benefit) for credit losses 33 21 11 3 — 68 Noninterest income 171 64 5 48 24 312 Noninterest expense 413 117 36 63 78 707 Provision (benefit) for income taxes 35 54 22 10 (62 ) 59 Net income (loss) $ 65 $ 100 $ 40 $ 17 $ (14 ) $ 208 Assets at Deposits at (dollar amounts in millions) March 31, December 31, March 31, December 31, Consumer & Business Banking $ 26,346 $ 26,220 $ 47,124 $ 45,643 Commercial Banking 32,744 32,118 21,838 21,235 Vehicle Finance 18,138 17,865 345 358 RBHPCG 5,888 5,821 6,053 6,057 Treasury / Other 21,130 22,161 4,111 3,748 Total $ 104,246 $ 104,185 $ 79,471 $ 77,041

ACCOUNTING STANDARDS UPDATE (Po

ACCOUNTING STANDARDS UPDATE (Policies)	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
ACCOUNTING STANDARDS UPDATE	ACCOUNTING STANDARDS UPDATE Accounting standards adopted in current period Standard Summary of guidance Effects on financial statements ASU 2014-09 - Revenue from Contracts with Customers (Topic 606): Issued May 2014 - Topic 606 supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, and most industry-specific guidance. - Requires an entity to recognize revenue upon 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. - Also requires additional qualitative and quantitative disclosures relating to the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers - Guidance sets forth a five step approach for revenue recognition. - Huntington adopted the new guidance on January 1, 2018 using the modified retrospective approach. - Management's analysis included: (a) Identification of all revenue streams included in the financial statements; (b) Determination of scope exclusions to identify ‘in-scope’ revenue streams; (c) Determination of size, timing, and amount of revenue recognition for in-scope items; (d) Identification of contracts for further analysis; and (e) Completion of a review of certain contracts to evaluate the potential impact of the new guidance. - Key revenue streams identified include service charges on deposit accounts, credit card and payment processing income, trust and investment management services income, and insurance income. Standard Summary of guidance Effects on financial statements ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities. Issued January 2016 - Improvements to GAAP disclosures including requiring an entity to: (a) Measure its equity investments with changes in the fair value recognized in the income statement. (b) Present separately in OCI the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments (i.e., FVO liability). (c) Use the exit price notion when measuring the fair value of financial instruments for disclosure purposes. (d) Assess deferred tax assets related to a net unrealized loss on AFS securities in combination with the entity’s other deferred tax assets. - Huntington adopted the new guidance in the on January 1, 2018. - Amendments are applied as a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. - Huntington reclassified $19 million of equity securities from AFS Securities to Other Securities on the Unaudited Condensed Consolidated Balance Sheets and reclassified unrealized gains of $1 million from AOCI to Retained Earnings. Prior periods have been adjusted to present these securities as Other Securities to facilitate comparison. ASU 2016-15 - Classification of Certain Cash Receipts and Cash Payments. Issued August 2016 - Clarifies guidance on the classification of certain cash receipts and payments in the statement of cash flows. - Provides consistent principles for evaluating the classification of cash payments and receipts in the statement of cash flows to reduce diversity in practice with respect to several types of cash flows. - Huntington adopted the new guidance on January 1, 2018. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. ASU 2017-07 - Improving the Presentation of Net Periodic Pension Cost and Periodic Postretirement Benefit Cost. Issued March 2017 - Requires that an employer report the service cost component of the pension cost and postretirement benefit cost in the same line items as other compensation costs arising from services rendered by the pertinent employees during the period. - Other components of the net benefit cost should be presented or disclosed separately in the income statement from the service cost component. - Huntington adopted the new guidance on January 1, 2018. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. ASU 2017-09 - Stock Compensation Modification Accounting. Issued May 2017 - Reduces the current diversity in practice and provides explicit guidance pertaining to the provisions of modification accounting. - Clarifies that an entity should account for effects of modification unless the fair value, vesting conditions and the classification of the modified award are the same as the original awards immediately before the original award is modified. - Huntington adopted the new guidance on January 1, 2018. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. Standard Summary of guidance Effects on financial statements ASU 2017-12 - Derivatives and Hedging - Targeted Improvements to Accounting for Hedging Activities. Issued August 2017 - Aligns the entity’s risk management activities and financial reporting for hedging relationships. - Requires an entity to present the earnings effect of the hedging instrument in the same income statement line item in which the earnings effect of the hedged item is reported. - Refines measurement techniques for hedges of benchmark interest rate risk. - Eliminates the separate measurement and reporting of hedge ineffectiveness. - Allows stated amount of assets in a closed portfolio to be fair value hedged by excluding proportion of hedged item related to prepayments, defaults and other events. - Eases hedge effectiveness testing including an option to perform qualitative testing. - For cash flow and net investment hedges, the cumulative-effect adjustment related to eliminating the separate measurement of ineffectiveness should be recognized in AOCI with a corresponding adjustment to retained earnings. - Huntington adopted the new guidance on January 1, 2018. The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. - Huntington reclassified $2.8 billion securities eligible to be hedged under the last-of-layer method from held-to-maturity to available-for-sale and recognized $26 million of fair value loss (net of tax) within OCI. ASU 2018-02 - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (Topic 220) Issued Feb 2018 - Allows an entity to elect a reclassification from accumulated other comprehensive income (AOCI) to retained earnings for stranded tax effects resulting from TCJA. - The amount of that reclassification should include the effect of changes of tax rate on the deferred tax amount, any related valuation allowance and other income tax effects on the items in AOCI. - Requires an entity to state if an election to reclassify the tax effect to retained earnings is made along with the description of other income tax effects that are reclassified from AOCI. - Effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years with earl y adoption permitted. - Huntington early adopted the guidance effective to 4Q 2017. Accounting standards yet to be adopted Standard Summary of guidance Effects on financial statements ASU 2016-02 - Leases. Issued February 2016 - New lease accounting model for lessors and lessees. For lessees, virtually all leases will be required to be recognized on the balance sheet by recording a right-of-use asset and lease liability. Subsequent accounting for leases varies depending on whether the lease is classified as an operating lease or a finance lease. - Accounting applied by a lessor is largely unchanged from that applied under the existing guidance. - Requires additional qualitative and quantitative disclosures with the objective of enabling users of financial statements to assess the amount, timing, and uncertainty of cash flows arising from leases. - Effective for the fiscal period beginning after December 15, 2018, with early application permitted. - Management intends to adopt the guidance on January 1, 2019, and has formed a working group comprised of associates from different disciplines, including Procurement, Real Estate, and Credit Administration, to evaluate the impact of the standard where Huntington is a lessee or lessor, as well as any impact to borrower’s financial statements. - Management is currently assessing the impact of the new guidance on Huntington's Unaudited Condensed Consolidated Financial Statements, including working with associates engaged in the procurement of goods and services used in the entity’s operations, and reviewing contractual arrangements for embedded leases in an effort to identify Huntington’s full lease population. - Huntington will recognize right-of-use assets and lease liabilities for virtually all of its operating lease commitments. Standard Summary of guidance Effects on financial statements ASU 2016-13 - Financial Instruments - Credit Losses. Issued June 2016 - Eliminates the probable recognition threshold for credit losses on financial assets measured at amortized cost. - Requires those financial assets to be presented at the net amount expected to be collected (i.e., net of expected credit losses). - Measurement of expected credit losses should be based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. - Effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018. - Adoption will be applied through a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective. - Management intends to adopt the guidance on January 1, 2020 and has formed a working group comprised of teams from different disciplines including credit and finance to evaluate the requirements of the new standard and the impact it will have on our processes. - The early stages of this evaluation include a review of existing credit models to identify areas where existing credit models used to comply with other regulatory requirements may be leveraged and areas where new impairment models may be required. ASU 2017-04 - Simplifying the Test for Goodwill Impairment. Issued January 2017 - Simplifies the goodwill impairment test by eliminating Step 2 of the goodwill impairment process, which requires an entity to determine the implied fair value of its goodwill by assigning fair value to all its assets and liabilities. - Entities will instead recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. - Entities will still have the option to perform the qualitative assessment for a reporting unit to determine if the quantitative impairment test is necessary. - Effective for annual and interim goodwill tests performed in fiscal years beginning after December 15, 2019. Early adoption is permitted. - The amendment is not expected to have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements.
Revenue Recognition	Huntington recognizes revenue when the performance obligations related to the transfer of goods or services under the terms of a contract are satisfied. Some obligations are satisfied at a point in time while others are satisfied over a period of time. Revenue is recognized as the amount of consideration to which Huntington expects to be entitled to in exchange for transferring goods or services to a customer. When consideration includes a variable component, the amount of consideration attributable to variability is included in the transaction price only to the extent it is probable that significant revenue recognized will not be reversed when uncertainty associated with the variable consideration is subsequently resolved. Generally, the variability relating to the consideration is explicitly stated in the contracts, but may also arise from Huntington's customer business practice, for example, waiving certain fees related to customer’s deposit accounts such as non-sufficient funds (“NSF”) fees. Huntington's contracts generally do not contain terms that require significant judgement to determine the variability impacting the transaction price. Revenue is measured as the amount of consideration Huntington expects to be entitled to in exchange for transferring goods or services. Revenue is segregated based on the nature of product and services offered as part of contractual arrangements. Revenue from contracts with customers is broadly segregated as follows. • Service charge on deposit accounts include fees and other charges Huntington receives to provide various services, including but not limited to, maintaining an account with a customer, providing overdraft services, wire transfer, transferring funds, and accepting and executing stop-payment orders. The consideration includes both fixed (e.g., account maintenance fee) and transaction fees (e.g., wire-transfer fee). The fixed fee is recognized over a period of time while the transaction fee is recognized when a specific service (e.g., execution of wire-transfer) is rendered to the customer. Huntington may, from time to time, waive certain fees (e.g., NSF fee) for customers but generally do not reduce the transaction price to reflect variability for future reversals due to the insignificance of the amounts. Waiver of fees reduces the revenue in the period the waiver is granted to the customer. • Cards and payment processing income includes interchange fee earned on debit cards and credit cards. All other fees (e.g. annual fees), and interest income are recognized in accordance with ASC 310. Huntington recognizes interchange fees for services performed related to authorization and settlement of a cardholder’s transaction with a merchant. Revenue is recognized when a cardholder’s transaction is approved and settled. The revenue may be constrained due to inherent uncertainty related to cardholder’s right to return goods and services but the uncertainty is resolved within a short period of time (generally within 30 days) and the amount of returns was not material for the reporting period ended March 31, 2018 . Revenue is not adjusted for such variability, rather returns reduce the amount of interchange revenue in the period the return is made by the customer. Certain volume or transaction based interchange expenses (net of rebates) paid to the payment network reduce the interchange revenue and is presented net on the income statement. Similarly, rewards payable under a reward program to cardholders are recognized as a reduction of the transaction price and are presented net against the interchange revenue. • Trust and investment management services income includes fee income generated from personal, corporate and institutional customers. Huntington also provides investment management services, cash management services as well as tax reporting to customers. Services are rendered over a period of time, over which revenue is recognized. Huntington may also recognize revenue from referring a customer to outside third-parties including mutual fund companies that pay distribution (12b-1) fees and other expenses. 12b-1 fees are received upon initially placing account holder’s funds with a mutual fund company as well as in the future periods as long as the account holder (i.e., the fund investor), remains invested in the fund. The transaction price includes variable consideration which is considered constrained as it is not probable that a significant revenue reversal in the amount of cumulative revenue recognized will not occur. Accordingly, those fees are recognized as revenue when the uncertainty associated with the variable consideration is subsequently resolved, that is, initial fees are recognized in the initial period while the future fees are recognized in future periods. Trust and investment management services also include commissions that are earned for placing a brokerage transaction for execution such as stocks or other investments. Revenue is recognized once the transaction is executed and Huntington is entitled to receive consideration. • Insurance income include agency commissions that are recognized when Huntington sells insurance policies to customers. Huntington is also entitled to renewal commissions and, in some cases, profit sharing which are recognized in subsequent periods. The initial commission is recognized when the insurance policy is sold to a customer. Renewal commission is variable consideration and is recognized in subsequent periods when the uncertainty around variable consideration is subsequently resolved (i.e., when customer renews the policy). Profit sharing is also a variable consideration that is not recognized until the variability surrounding realization of revenue is resolved (i.e., Huntington have reached a minimum volume of sales). Another source of variability is the ability of the policy holder to cancel the policy anytime and in such cases, Huntington may be required, under the terms of the contract, to return part of the commission received. The variability related to cancellation of the policy is not deemed significant and thus, does not impact the amount of revenue recognized. In the event the policyholder chooses to cancel the policy at any time, the revenue for amounts which qualify for claw-back are reversed in the period the cancellation occurs. • Other noninterest income includes a variety of other revenue streams including capital markets revenue, consumer fees and marketing allowance revenue. Revenue is recognized when, or as, a performance obligation is satisfied. Inherent variability in the transaction price is not recognized until the uncertainty affecting the variability is resolved. Control is transferred to a customer either at a point in time or over time. A performance obligation is deemed satisfied when the control over goods or services is transferred to the customer. To determine when control is transferred at a point in time, Huntington considers indicators, including but not limited to the right to payment for the asset, transfer of significant risk and rewards of ownership of the asset and acceptance of asset by the customer. When control is transferred over a period of time, for different performance obligations, either the input or output method is used to determine the progress. The measure of progress used to assess completion of the performance obligation varies between performance obligations and may be based on time throughout the period of service or on the value of goods and services transferred to the customer. As each distinct service or activity is performed, Huntington transfers control to the customer based on the services performed as the customer simultaneously receives the benefits of those services. This timing of revenue recognition aligns with the resolution of any uncertainty related to variable consideration. Costs incurred to obtain a revenue producing contract is expensed when incurred as a practical expedient as the contractual period for majority of contracts is one year or less. Revenue is recorded in the business segment responsible for the related product or service. Fee sharing arrangements exist to allocate portions of such revenue to other business segments involved in selling to, or providing service to, customers. Business segment results are determined based upon management's reporting system, which assigns balance sheet and income statement items to each of the business segments. The process is designed around Huntington's organizational and management structure and, accordingly, the results derived are not necessarily comparable with similar information published by other financial institutions.

LOANS _ LEASES AND ALLOWANCE 27

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES (Tables)	3 Months Ended
	Mar. 31, 2018
Receivables [Abstract]
Loan and Lease Portfolio	The following table provides a detailed listing of Huntington’s loan and lease portfolio at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) March 31, 2018 December 31, 2017 Loans and leases: Commercial and industrial $ 28,622 $ 28,107 Commercial real estate 7,412 7,225 Automobile 12,146 12,100 Home equity 9,987 10,099 Residential mortgage 9,357 9,026 RV and marine finance 2,549 2,438 Other consumer 1,090 1,122 Loans and leases $ 71,163 $ 70,117 Allowance for loan and lease losses (721 ) (691 ) Net loans and leases $ 70,442 $ 69,426
NALs and Past Due Loans	The following table presents NALs by loan class at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) March 31, December 31, Commercial and industrial $ 190 $ 161 Commercial real estate 30 29 Automobile 5 6 Home equity 75 68 Residential mortgage 82 84 RV and marine finance 1 1 Other consumer — — Total nonaccrual loans $ 383 $ 349
Aging analysis of loans and leases	The following table presents an aging analysis of loans and leases, including past due loans and leases, by loan class at March 31, 2018 and December 31, 2017 : March 31, 2018 Past Due (1) Loans Accounted for Under FVO Total Loans 90 or (dollar amounts in millions) 30-59 60-89 90 or Total Current Commercial and industrial $ 39 $ 13 $ 65 $ 117 $ 28,505 $ — $ 28,622 $ 9 (2) Commercial real estate 13 — 6 19 7,393 — 7,412 1 Automobile 66 13 8 87 12,058 1 12,146 6 Home equity 55 20 62 137 9,848 2 9,987 15 Residential mortgage 89 37 115 241 9,034 82 9,357 69 (3) RV and marine finance 8 2 1 11 2,537 1 2,549 2 Other consumer 9 4 4 17 1,073 — 1,090 4 Total loans and leases $ 279 $ 89 $ 261 $ 629 $ 70,448 $ 86 $ 71,163 $ 106 December 31, 2017 Past Due (1) Purchased Loans Accounted for Under FVO Total Loans 90 or (dollar amounts in millions) 30-59 60-89 90 or Total Current Commercial and industrial 35 14 65 114 27,954 39 — 28,107 9 (2) Commercial real estate 10 1 11 22 7,201 2 — 7,225 3 Automobile 89 18 10 117 11,982 — 1 12,100 7 Home equity 49 19 60 128 9,969 — 2 10,099 18 Residential mortgage 129 48 118 295 8,642 — 89 9,026 72 (3) RV and marine finance 11 3 2 16 2,421 — 1 2,438 1 Other consumer 12 5 5 22 1,100 — — 1,122 5 Total loans and leases $ 335 $ 108 $ 271 $ 714 $ 69,269 $ 41 $ 93 $ 70,117 $ 115 (1) NALs are included in this aging analysis based on the loan's past due status. (2) Amounts include Huntington Technology Finance administrative lease delinquencies. (3) Amounts include mortgage loans insured by U.S. government agencies.
ALLL and AULC activity by portfolio segment	The following table presents ALLL and AULC activity by portfolio segment for the three-month periods ended March 31, 2018 and 2017 . (dollar amounts in millions) Commercial Consumer Total Three-month period ended March 31, 2018: ALLL balance, beginning of period $ 482 $ 209 $ 691 Loan charge-offs (23 ) (50 ) (73 ) Recoveries of loans previously charged-off 20 15 35 Provision for loan and lease losses 36 32 68 ALLL balance, end of period $ 515 $ 206 $ 721 AULC balance, beginning of period $ 84 $ 3 $ 87 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (2 ) — (2 ) AULC balance, end of period $ 82 $ 3 $ 85 ACL balance, end of period $ 597 $ 209 $ 806 (dollar amounts in millions) Commercial Consumer Total Three-month period ended March 31, 2017: ALLL balance, beginning of period $ 451 $ 187 $ 638 Loan charge-offs (24 ) (46 ) (70 ) Recoveries of loans previously charged-off 18 13 31 Provision for loan and lease losses 35 39 74 ALLL balance, end of period $ 480 $ 193 $ 673 AULC balance, beginning of period $ 87 $ 11 $ 98 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 2 (8 ) (6 ) AULC balance, end of period $ 89 $ 3 $ 92 ACL balance, end of period $ 569 $ 196 $ 765
Loan and lease balances by credit quality indicator	The following table presents each loan and lease class by credit quality indicator at March 31, 2018 and December 31, 2017 . March 31, 2018 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 26,719 $ 747 $ 1,142 $ 14 $ 28,622 Commercial real estate 7,049 222 139 2 7,412 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,114 $ 4,338 $ 1,395 $ 298 $ 12,145 Home equity 6,247 3,025 631 82 9,985 Residential mortgage 5,976 2,591 621 87 9,275 RV and marine finance 1,529 866 104 49 2,548 Other consumer 408 549 96 37 1,090 December 31, 2017 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 26,268 $ 694 $ 1,116 $ 29 $ 28,107 Commercial real estate 6,909 200 115 1 7,225 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,102 $ 4,312 $ 1,390 $ 295 $ 12,099 Home equity 6,352 3,024 617 104 10,097 Residential mortgage 5,697 2,581 605 54 8,937 RV and marine finance 1,433 863 96 45 2,437 Other consumer 428 540 143 11 1,122 (1) Excludes loans accounted for under the fair value option. (2) Reflects updated customer credit scores. (3) Reflects deferred fees and costs, loans in process, etc.
Summarized data for impaired loans and the related ALLL by portfolio segment	The following tables present the balance of the ALLL attributable to loans by portfolio segment individually and collectively evaluated for impairment and the related loan and lease balance at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) Commercial Consumer Total ALLL at March 31, 2018: Portion of ALLL balance: Attributable to loans individually evaluated for impairment $ 36 $ 9 $ 45 Attributable to loans collectively evaluated for impairment 479 197 676 Total ALLL balance $ 515 $ 206 $ 721 Loan and Lease Ending Balances at March 31, 2018: (1) Portion of loan and lease ending balance: Individually evaluated for impairment $ 670 $ 610 $ 1,280 Collectively evaluated for impairment 35,364 34,433 69,797 Total loans and leases evaluated for impairment $ 36,034 $ 35,043 $ 71,077 (1) Excludes loans accounted for under the fair value option. (dollar amounts in millions) Commercial Consumer Total ALLL at December 31, 2017: Portion of ALLL balance: Attributable to purchased credit-impaired loans $ — $ — $ — Attributable to loans individually evaluated for impairment 32 9 41 Attributable to loans collectively evaluated for impairment 450 200 650 Total ALLL balance: $ 482 $ 209 $ 691 Loan and Lease Ending Balances at December 31, 2017: (1) Portion of loan and lease ending balances: Attributable to purchased credit-impaired loans $ 41 $ — $ 41 Individually evaluated for impairment 607 616 1,223 Collectively evaluated for impairment 34,684 34,076 68,760 Total loans and leases evaluated for impairment $ 35,332 $ 34,692 $ 70,024 (1) Excludes loans accounted for under the fair value option.
Detailed impaired loan information by class	The following tables present by class the ending, unpaid principal balance, and the related ALLL, along with the average balance and interest income recognized only for impaired loans and leases: (1) March 31, 2018 Three Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 243 $ 271 $ — $ 264 $ 5 Commercial real estate 71 91 — 63 2 Automobile — — — — — Home equity — — — — — Residential mortgage — — — — — RV and marine finance — — — — — Other consumer — — — — — With an allowance recorded: Commercial and industrial 314 349 34 286 3 Commercial real estate 42 48 2 47 — Automobile 37 41 2 36 1 Home equity 335 386 14 334 3 Residential mortgage 307 335 4 308 3 RV and marine finance 2 3 — 2 — Other consumer 6 6 2 7 — Total Commercial and industrial (3) 557 620 34 550 8 Commercial real estate (4) 113 139 2 110 2 Automobile (2) 37 41 2 36 1 Home equity (5) 335 386 14 334 3 Residential mortgage (5) 307 335 4 308 3 RV and marine finance (2) 2 3 — 2 — Other consumer (2) 6 6 2 7 — December 31, 2017 Three Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 284 $ 311 $ — $ 276 $ 4 Commercial real estate 56 81 — 86 2 Automobile — — — — — Home equity — — — — — Residential mortgage — — — — — RV and marine finance — — — — — Other consumer — — — — — With an allowance recorded: Commercial and industrial 257 280 29 334 2 Commercial real estate 51 51 3 69 — Automobile 36 40 2 32 1 Home equity 334 385 14 323 4 Residential mortgage 308 338 4 339 3 RV and marine finance 2 3 — — — Other consumer 8 8 2 4 — Total Commercial and industrial (3) 541 591 29 610 6 Commercial real estate (4) 107 132 3 155 2 Automobile (2) 36 40 2 32 1 Home equity (5) 334 385 14 323 4 Residential mortgage (5) 308 338 4 339 3 RV and marine finance (2) 2 3 — — — Other consumer (2) 8 8 2 4 — (1) These tables do not include loans fully charged-off. (2) All automobile, RV and marine finance and other consumer impaired loans included in these tables are considered impaired due to their status as a TDR. (3) At March 31, 2018 and December 31, 2017 , C&I loans of $399 million and $382 million , respectively, were considered impaired due to their status as a TDR. (4) At March 31, 2018 and December 31, 2017 , CRE loans of $92 million and $93 million , respectively, were considered impaired due to their status as a TDR. (5) Includes home equity and residential mortgages considered to be collateral dependent due to their non-accrual status as well as home equity and mortgage loans considered impaired due to their status as a TDR. (6) The differences between the ending balance and unpaid principal balance amounts represent partial charge-offs.
Detailed troubled debt restructuring information by class	The following table presents, by class and modification type, the number of contracts, post-modification outstanding balance, and the financial effects of the modification for the three-month periods ended March 31, 2018 and 2017 . New Troubled Debt Restructurings During The Three-Month Period Ended (1) March 31, 2018 March 31, 2017 (dollar amounts in millions) Number of Contracts Post-modification Outstanding Balance (2) Financial effects of modification (3) Number of Contracts Post-modification Outstanding Balance (2) Financial effects of modification (3) Commercial and industrial: Interest rate reduction 1 $ — $ — 1 $ — $ — Amortization or maturity date change 238 96 (2 ) 236 113 (1 ) Other 2 — — 3 — — Total Commercial and industrial 241 96 (2 ) 240 113 (1 ) Commercial real estate: Interest rate reduction — — — — — — Amortization or maturity date change 48 32 — 24 31 — Other — — — — — — Total commercial real estate: 48 32 — 24 31 — Automobile: Interest rate reduction 16 — — 14 — — Amortization or maturity date change 411 4 — 477 4 — Chapter 7 bankruptcy 200 2 — 240 2 — Other — — — — — — Total Automobile 627 6 — 731 6 — Home equity: Interest rate reduction 1 — — 8 — — Amortization or maturity date change 85 5 (1 ) 106 5 (1 ) Chapter 7 bankruptcy 51 3 — 87 4 1 Other 7 — — 58 4 — Total Home equity 144 8 (1 ) 259 13 — Residential mortgage: Interest rate reduction — — — 2 — — Amortization or maturity date change 72 9 — 99 11 (1 ) Chapter 7 bankruptcy 10 — — 24 3 — Other 1 — — 16 2 — Total Residential mortgage 83 9 — 141 16 (1 ) RV and marine finance: Interest rate reduction — — — — — — Amortization or maturity date change 3 — — 14 1 — Chapter 7 bankruptcy 16 — — 15 — — Other — — — — — — Total RV and marine finance 19 — — 29 1 — Other consumer: Interest rate reduction 440 2 — 1 — — Amortization or maturity date change — — — 2 — — Chapter 7 bankruptcy 1 — — 1 — — Other — — — — — — Total Other consumer 441 2 — 4 — — Total new troubled debt restructurings 1,603 $ 153 $ (3 ) 1,428 $ 180 $ (2 ) (1) TDRs may include multiple concessions and the disclosure classifications are based on the primary concession provided to the borrower. (2) Post-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of a restructuring are not significant. (3) Amount represents the financial impact via provision for loan and lease losses as a result of the modification.

AVAILABLE-FOR-SALE SECURITIES (

AVAILABLE-FOR-SALE SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Contractual maturities of investment securities	ontractual maturities of available-for-sale securities at March 31, 2018 and December 31, 2017 were: March 31, 2018 December 31, 2017 (dollar amounts in millions) Amortized Cost Fair Value Amortized Cost Fair Value U.S. Treasury, Federal agency, and other agency securities: U.S. Treasury: 1 year or less $ 5 $ 5 $ 5 $ 5 Total U.S. Treasury 5 5 5 5 Federal agencies: Residential CMO: After 1 year through 5 years 1 1 1 1 After 5 years through 10 years 47 45 90 89 After 10 years 7,742 7,485 6,570 6,394 Total Residential CMO 7,790 7,531 6,661 6,484 Residential MBS: After 1 year through 5 years 6 5 6 6 After 5 years through 10 years 33 33 7 8 After 10 years 700 686 1,358 1,353 Total Residential MBS 739 724 1,371 1,367 Commercial MBS: After 1 year through 5 years 69 67 23 22 After 5 years through 10 years 9 8 151 148 After 10 years 1,775 1,716 2,365 2,317 Total Commercial MBS 1,853 1,791 2,539 2,487 Other agencies: 1 year or less 1 1 2 2 After 1 year through 5 years 8 8 9 9 After 5 years through 10 years 181 178 58 59 Total other agencies 190 187 69 70 Total U.S. Treasury, Federal agency, and other agency securities 10,577 10,238 10,645 10,413 Municipal securities: 1 year or less 153 153 103 103 After 1 year through 5 years 1,129 1,121 1,140 1,134 After 5 years through 10 years 1,738 1,717 1,709 1,704 After 10 years 867 843 940 937 Total municipal securities 3,887 3,834 3,892 3,878 Asset-backed securities: After 1 year through 5 years 80 79 80 80 After 5 years through 10 years 61 60 53 54 After 10 years 294 288 349 333 Total asset-backed securities 435 427 482 467 Corporate debt: 1 year or less 1 1 — — After 1 year through 5 years 67 67 73 74 After 5 years through 10 years 19 20 20 21 After 10 years 13 14 13 14 Total corporate debt 100 102 106 109 Other securities/Sovereign debt: 1 year or less 2 2 1 1 After 1 year through 5 years 4 4 1 1 Total other securities/Sovereign debt 6 6 2 2 Total available-for-sale securities $ 15,005 $ 14,607 $ 15,127 $ 14,869
Amortized cost, fair value, and gross unrealized gains and losses recognized in accumulated other comprehensive income	The following tables provide amortized cost, fair value, and gross unrealized gains and losses recognized in OCI by investment category at March 31, 2018 and December 31, 2017 : Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value March 31, 2018 U.S. Treasury $ 5 $ — $ — $ 5 Federal agencies: Residential CMO 7,790 — (259 ) 7,531 Residential MBS 739 2 (16 ) 724 Commercial MBS 1,853 — (63 ) 1,791 Other agencies 190 — (3 ) 187 Total U.S. Treasury, Federal agency and other agency securities 10,577 2 (341 ) 10,238 Municipal securities 3,887 14 (67 ) 3,834 Asset-backed securities 435 — (8 ) 427 Corporate debt 100 2 — 102 Other securities/Sovereign debt 6 — — 6 Total available-for-sale securities $ 15,005 $ 18 $ (416 ) $ 14,607 Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value December 31, 2017 U.S. Treasury $ 5 $ — $ — $ 5 Federal agencies: Residential CMO 6,661 1 (178 ) 6,484 Residential MBS 1,371 1 (5 ) 1,367 Commercial MBS 2,539 — (52 ) 2,487 Other agencies 69 1 — 70 Total U.S. Treasury, Federal agency and other agency securities 10,645 3 (235 ) 10,413 Municipal securities 3,892 21 (35 ) 3,878 Asset-backed securities 482 1 (16 ) 467 Corporate debt 106 3 — 109 Other securities/Sovereign debt 2 — — 2 Total available-for-sale securities $ 15,127 $ 28 $ (286 ) $ 14,869
Available for sale securities in an unrealized loss position table text block	The following tables provide detail on investment securities with unrealized losses aggregated by investment category and the length of time the individual securities have been in a continuous loss position as of March 31, 2018 and December 31, 2017 . Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses March 31, 2018 Federal agencies: Residential CMO $ 3,291 $ (71 ) $ 4,027 $ (188 ) $ 7,318 $ (259 ) Residential MBS 648 (16 ) 11 — 659 (16 ) Commercial MBS 322 (9 ) 1,469 (54 ) 1,791 (63 ) Other agencies 107 (1 ) 69 (2 ) 176 (3 ) Total Federal Agency and other agency securities 4,368 (97 ) 5,576 (244 ) 9,944 (341 ) Municipal securities 2,182 (45 ) 623 (22 ) 2,805 (67 ) Asset-backed securities 240 (3 ) 144 (5 ) 384 (8 ) Corporate debt 14 — — — 14 — Other securities/Sovereign debt — — 2 — 2 — Total temporarily impaired securities $ 6,804 $ (145 ) $ 6,345 $ (271 ) $ 13,149 $ (416 ) Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2017 Federal agencies: Residential CMO $ 1,660 $ (19 ) $ 4,520 $ (159 ) $ 6,180 $ (178 ) Residential MBS 1,078 (5 ) 11 — 1,089 (5 ) Commercial MBS 960 (15 ) 1,527 (37 ) 2,487 (52 ) Other agencies 39 — — — 39 — Total Federal Agency and other agency securities 3,737 (39 ) 6,058 (196 ) 9,795 (235 ) Municipal securities 1,681 (21 ) 497 (14 ) 2,178 (35 ) Asset-backed securities 127 (1 ) 173 (15 ) 300 (16 ) Total temporarily impaired securities $ 5,545 $ (61 ) $ 6,728 $ (225 ) $ 12,273 $ (286 )
Realized securities gains and losses	The following table is a summary of realized securities gains and losses for the three-month periods ended March 31, 2018 and 2017 , respectively. Three Months Ended (dollar amounts in millions) 2018 2017 Gross gains on sales of securities $ 5 $ 1 Gross (losses) on sales of securities (5 ) (1 ) Net gain on sales of securities $ — $ —
Trust Preferred Securities Data	.
Schedule of other than temporary impairment	. During the 2018 first quarter, Huntington sold the remaining trust preferred CDO securities resulting in a gain of $3 million . As of March 31, 2018 , the Huntington has evaluated available-for-sale securities with gross unrealized losses for impairment and concluded no OTTI is required.

HELD-TO-MATURITY SECURITIES (Ta

HELD-TO-MATURITY SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Contractual maturities of held-to-maturity securities	Listed below are the contractual maturities of held-to-maturity securities at March 31, 2018 and December 31, 2017 . March 31, 2018 December 31, 2017 (dollar amounts in millions) Amortized Cost Fair Value Amortized Cost Fair Value Federal agencies: Residential CMO: After 5 years through 10 years 39 38 — — After 10 years 2,354 2,291 3,714 3,657 Total Residential CMO 2,393 2,329 3,714 3,657 Residential MBS: After 5 years through 10 years — — 28 28 After 10 years 1,651 1,606 1,021 1,016 Total Residential MBS 1,651 1,606 1,049 1,044 Commercial MBS: After 1 year through 5 years — — 38 37 After 5 years through 10 years 131 128 1 1 After 10 years 4,223 4,101 3,752 3,698 Total Commercial MBS 4,354 4,229 3,791 3,736 Other agencies: After 1 year through 5 years 14 13 7 8 After 5 years through 10 years 215 213 362 360 After 10 years 157 154 163 161 Total other agencies 386 380 532 529 Total Federal agencies and other agencies 8,784 8,544 9,086 8,966 Municipal securities: After 10 years 5 5 5 5 Total municipal securities 5 5 5 5 Total held-to-maturity securities $ 8,789 $ 8,549 $ 9,091 $ 8,971
Amortized cost, gross unrealized gains and losses, and fair value by investment category	The following table provides amortized cost, gross unrealized gains and losses, and fair value by investment category at March 31, 2018 and December 31, 2017 . Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value March 31, 2018 Federal agencies: Residential CMO $ 2,393 $ — $ (63 ) $ 2,329 Residential MBS 1,651 — (45 ) 1,606 Commercial MBS 4,354 — (125 ) 4,229 Other agencies 386 — (6 ) 380 Total Federal agencies and other agencies 8,784 — (239 ) 8,544 Municipal securities 5 — — 5 Total held-to-maturity securities $ 8,789 $ — $ (239 ) $ 8,549 Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value December 31, 2017 Federal agencies: Residential CMO $ 3,714 $ 1 $ (58 ) $ 3,657 Residential MBS 1,049 2 (7 ) 1,044 Commercial MBS 3,791 — (55 ) 3,736 Other agencies 532 1 (4 ) 529 Total Federal agencies and other agencies 9,086 4 (124 ) 8,966 Municipal securities 5 — — 5 Total held-to-maturity securities $ 9,091 $ 4 $ (124 ) $ 8,971
Investment securities in an unrealized loss position	The following tables provide detail on HTM securities with unrealized losses aggregated by investment category and the length of time the individual securities have been in a continuous loss position, at March 31, 2018 and December 31, 2017 . Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Gross Unrealized Fair Gross Unrealized Fair Gross Unrealized March 31, 2018 Federal agencies: Residential CMO $ 947 $ (23 ) $ 1,313 $ (40 ) $ 2,260 $ (63 ) Residential MBS 1,606 (45 ) — — 1,606 (45 ) Commercial MBS 3,495 (109 ) 726 (16 ) 4,221 (125 ) Other agencies 297 (4 ) 62 (2 ) 359 (6 ) Total Federal agencies and other agencies 6,345 (181 ) 2,101 (58 ) 8,446 (239 ) Municipal securities — — 5 — 5 — Total temporarily impaired securities $ 6,345 $ (181 ) $ 2,106 $ (58 ) $ 8,451 $ (239 ) Less than 12 Months Over 12 Months Total (dollar amounts in millions) Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses Fair Value Gross Unrealized Losses December 31, 2017 Federal agencies: Residential CMO $ 2,369 $ (26 ) $ 1,019 $ (32 ) $ 3,388 $ (58 ) Residential MBS 974 (7 ) — — 974 (7 ) Commercial MBS 3,456 (49 ) 253 (6 ) 3,709 (55 ) Other agencies 249 (2 ) 139 (2 ) 388 (4 ) Total Federal agencies and other agencies 7,048 (84 ) 1,411 (40 ) 8,459 (124 ) Municipal securities — — 5 — 5 — Total temporarily impaired securities $ 7,048 $ (84 ) $ 1,416 $ (40 ) $ 8,464 $ (124 )

OTHER SECURITIES (Tables)

OTHER SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Other Securities [Table Text Block]	March 31, 2018 December 31, 2017 (dollar amounts in millions) Amortized Cost Fair Value Amortized Cost Fair Value Other securities, at cost Non-marketable equity securities: Federal Home Loan Bank stock 287 287 287 287 Federal Reserve Bank stock 294 294 294 294 Other securities, at fair value Mutual funds 19 19 18 18 Marketable equity securities 2 2 1 1 Total other securities $ 602 $ 602 $ 600 $ 600 Other securities are primarily composed of FHLB stock and FRB stock (which are carried at cost) and mutual funds and other marketable equity securities (which are carried at fair value, with changes in fair value recognized in other noninterest income). Other securities that are carried at cost are reviewed at least annually for impairment, with valuation adjustments recognized in other noninterest income.

LOAN SALES AND SECURITIZATIONS

LOAN SALES AND SECURITIZATIONS (Tables)	3 Months Ended
	Mar. 31, 2018
Transfers and Servicing [Abstract]
Summarizes activity relating to loans securitized sold with servicing retained	The following table summarizes activity relating to residential mortgage loans sold with servicing retained for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 Residential mortgage loans sold with servicing retained $ 843 $ 845 Pretax gains resulting from above loan sales (1) 21 22 (1) Recorded in mortgage banking income. The following table summarizes activity relating to SBA loans sold with servicing retained for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 SBA loans sold with servicing retained $ 64 $ 78 Pretax gains resulting from above loan sales (1) 7 6 (1) Recorded in gain on sale of loans.
Summarizes activity relating to loans sold with servicing retained using the fair value method	Changes in the carrying value of automobile loan servicing rights for the three-month periods ended March 31, 2018 and 2017 , and the fair value at the end of each period were as follows: Three Months Ended (dollar amounts in millions) 2018 2017 Carrying value, beginning of period $ 8 $ 18 Amortization (2 ) (3 ) Carrying value, end of period $ 6 $ 15 Fair value, end of period $ 7 $ 15 Weighted-average contractual life (years) 3.4 4.0 The following table summarizes the changes in the carrying value of the servicing asset for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 Carrying value, beginning of period $ 27 $ 21 New servicing assets created 3 1 Amortization (2 ) (1 ) Carrying value, end of period $ 28 $ 21 Fair value, end of period $ 32 $ 26 Weighted-average life (years) 3.3 3.3
Summarizes activity relating to loans sold with servicing retained using the amortization method	The following table summarizes the changes in MSRs recorded using the amortization method for the three-month periods ended March 31, 2018 and 2017 : Three Months Ended (dollar amounts in millions) 2018 2017 Carrying value, beginning of period $ 191 $ 172 New servicing assets created 10 10 Impairment recovery (charge) 7 2 Amortization (8 ) (6 ) Carrying value, end of period $ 200 $ 178 Fair value, end of period $ 205 $ 179 Weighted-average life (years) 7.0 7.1
Summary of key assumptions and the sensitivity of the servicing rights value to changes in the assumptions	For MSRs under the amortization method, a summary of key assumptions and the sensitivity of the MSR value to changes in these assumptions at March 31, 2018 , and December 31, 2017 follows: March 31, 2018 December 31, 2017 Decline in fair value due to Decline in fair value due to (dollar amounts in millions) Actual 10% 20% Actual 10% 20% Constant prepayment rate (annualized) 8.42 % $ (9 ) $ (18 ) 8.30 % $ (5 ) $ (10 ) Spread over forward interest rate swap rates 979 bps (8 ) (14 ) 1,049 bps (7 ) (13 )

OTHER COMPREHENSIVE INCOME (Tab

OTHER COMPREHENSIVE INCOME (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Components of other comprehensive income	The components of Huntington's OCI for the three-month periods ended March 31, 2018 and 2017 , were as follows: Three Months Ended Tax (Expense) (dollar amounts in millions) Pretax Benefit After-tax Noncredit-related impairment recoveries (losses) on debt securities not expected to be sold $ — $ — $ — Unrealized holding gains (losses) on available-for-sale debt securities arising during the period (206 ) 45 (161 ) Less: Reclassification adjustment for net losses (gains) included in net income 15 (3 ) 12 Net change in unrealized holding gains (losses) on available-for-sale debt securities (191 ) 42 (149 ) Net change in pension and other post-retirement obligations 1 — 1 Total other comprehensive income (loss) $ (190 ) $ 42 $ (148 ) Three Months Ended Tax (Expense) (dollar amounts in millions) Pretax Benefit After-tax Noncredit-related impairment recoveries (losses) on debt securities not expected to be sold $ 1 $ — $ 1 Unrealized holding gains (losses) on available-for-sale debt securities arising during the period 9 (3 ) 6 Less: Reclassification adjustment for net losses (gains) included in net income 6 (2 ) 4 Net change in unrealized holding gains (losses) on available-for-sale debt securities 16 (5 ) 11 Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period (2 ) 1 (1 ) Less: Reclassification adjustment for net (gains) losses included in net income 1 (1 ) — Net change in unrealized gains (losses) on derivatives used in cash flow hedging relationships (1 ) — (1 ) Net change in pension and other post-retirement obligations — — — Total other comprehensive income (loss) $ 15 $ (5 ) $ 10
Activity in accumulated other comprehensive income, net of tax	ctivity in accumulated OCI for the three -month periods ended March 31, 2018 and 2017 , were as follows: (dollar amounts in millions) Unrealized gains and (losses) on debt securities (1) Unrealized gains and (losses) on cash flow hedging derivatives Unrealized gains (losses) for pension and other post- retirement obligations Total December 31, 2016 $ (193 ) $ (3 ) $ (205 ) $ (401 ) Other comprehensive income before reclassifications 7 (1 ) — 6 Amounts reclassified from accumulated OCI to earnings 4 — — 4 Period change 11 (1 ) — 10 March 31, 2017 $ (182 ) $ (4 ) $ (205 ) $ (391 ) December 31, 2017 $ (278 ) $ — $ (250 ) $ (528 ) Cumulative-effect adjustments (ASU 2016-01) (1 ) — — (1 ) Other comprehensive income before reclassifications (161 ) — — (161 ) Amounts reclassified from accumulated OCI to earnings 12 — 1 13 Period change (149 ) — 1 (148 ) March 31, 2018 $ (428 ) $ — $ (249 ) $ (677 )
Reclassification Out Of Accumulated OCI	The following table presents the reclassification adjustments out of accumulated OCI included in net income and the impacted line items as listed on the Unaudited Condensed Consolidated Statements of Income for the three-month periods ended March 31, 2018 and 2017 : Reclassifications out of accumulated OCI Accumulated OCI components Amounts reclassified from accumulated OCI Location of net gain (loss) reclassified from accumulated OCI into earnings Three Months Ended (dollar amounts in millions) March 31, 2018 March 31, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (3 ) $ (4 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities (12 ) (2 ) Noninterest income - net gains (losses) on sale of securities OTTI recorded — — Noninterest income - net gains (losses) on sale of securities Total before tax (15 ) (6 ) Tax (expense) benefit 3 2 Net of tax $ (12 ) $ (4 ) Gains (losses) on cash flow hedging relationships: Interest rate contracts $ — $ (1 ) Interest income - loans and leases Total before tax — (1 ) Tax (expense) benefit — 1 Net of tax $ — $ — Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ 2 $ (1 ) Noninterest expense - personnel costs Net periodic benefit costs (1 ) 1 Noninterest expense - personnel costs Total before tax 1 — Tax (expense) benefit — — Net of tax $ 1 $ —

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Schedule of Preferred Stock	The following is a summary of Huntington's non-cumulative perpetual preferred stock outstanding as of March 31, 2018 . (dollar amounts in millions, except per share amounts) Series Description Issuance Date Total Shares Outstanding Carrying Amount Dividend Rate Earliest Redemption Date Series B Non-cumulative, non-voting, perpetual 12/28/2011 35,500 23 3-mo. LIBOR + 270 bps 1/15/2017 Series D Non-cumulative, non-voting perpetual 3/21/2016 400,000 386 6.25 % 7/15/2021 Series D Non-cumulative, non-voting perpetual 5/5/2016 200,000 199 6.25 % 7/15/2021 Series C Non-cumulative, non-voting perpetual 8/16/2016 100,000 100 5.875 % 1/15/2022 Series E Non-cumulative, non-voting perpetual 2/27/2018 5,000 495 5.700 % 4/15/2023 Total 740,500 1,203

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Basic and diluted earnings loss per share	The calculation of basic and diluted earnings per share for the three -month periods ended March 31, 2018 and 2017 was as follows: Three Months Ended (dollar amounts in millions, except per share amounts) 2018 2017 Basic earnings per common share: Net income $ 326 $ 208 Preferred stock dividends (12 ) (19 ) Net income available to common shareholders $ 314 $ 189 Average common shares issued and outstanding (000) 1,083,836 1,086,374 Basic earnings per common share $ 0.29 $ 0.17 Diluted earnings per common share: Net income available to common shareholders $ 314 $ 189 Effect of assumed preferred stock conversion — — Net income applicable to diluted earnings per share $ 314 $ 189 Average common shares issued and outstanding (000) 1,083,836 1,086,374 Dilutive potential common shares: Stock options and restricted stock units and awards 19,858 19,139 Shares held in deferred compensation plans 3,228 2,953 Dilutive impact of Preferred Stock 17,856 — Other — 151 Dilutive potential common shares 40,942 22,243 Total diluted average common shares issued and outstanding (000) 1,124,778 1,108,617 Diluted earnings per common share $ 0.28 $ 0.17

NON-INTEREST INCOME (Tables)

NON-INTEREST INCOME (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Non-interest Income	The following table shows Huntington’s total noninterest income segregated between contracts with customers within the scope of ASC 606 and those within the scope of other GAAP Topics. (dollar amounts in millions) Three Months Ended March 31, 2018 Non-interest income Noninterest income from contracts with customers $ 214 Noninterest income within the scope of other GAAP topics 100 Total noninterest income $ 314 The following table illustrates the disaggregation by operating segment and major revenue stream and reconciles disaggregated revenue to segment revenue presented in Note 17 . (dollar amounts in millions) Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated Major Revenue Streams Service charges on deposit accounts $ 68 $ 16 $ 1 $ 1 $ — $ 86 Cards and payment processing income 47 2 — — — 49 Trust and investment management services 7 1 — 36 — 44 Insurance income 8 1 — 11 1 21 Other Income 10 — 1 3 — 14 Net revenue from contracts with customers $ 140 $ 20 $ 2 $ 51 $ 1 $ 214 Noninterest income within the scope of other GAAP topics 34 49 1 — 16 100 Total noninterest income $ 174 $ 69 $ 3 $ 51 $ 17 $ 314

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	3 Months Ended
	Mar. 31, 2018
Retirement Benefits [Abstract]
Schedule of Net Benefit Costs	The following table shows the components of net periodic (benefit) cost for all plans: Pension Benefits (1) Post-Retirement Benefits (1) Three Months Ended March 31, Three Months Ended March 31, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ 1 $ 1 $ — $ — Interest cost 7 7 — — Expected return on plan assets (12 ) (14 ) — — Amortization of prior service cost — — (1 ) — Amortization of loss 2 2 — — Settlements 3 3 — — Net periodic (benefit) cost $ 1 $ (1 ) $ (1 ) $ — (1) All pension and post-retirement (benefits) costs are recorded in Other Income on the Condensed Consolidated Statements of Income.
Schedule of Costs of Retirement Plans	defined contribution plans during the first quarter 2018 and 2017 was $11 million and $11 million , respectively.

FAIR VALUES OF ASSETS AND LIA37

FAIR VALUES OF ASSETS AND LIABILITIES (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value on a recurring basis	Assets and Liabilities measured at fair value on a recurring basis Assets and liabilities measured at fair value on a recurring basis at March 31, 2018 and December 31, 2017 are summarized below: Fair Value Measurements at Reporting Date Using Netting Adjustments (1) March 31, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Municipal securities $ — $ 2 — — $ 2 Other securities 82 1 — — 83 82 3 — — 85 Available-for-sale securities: U.S. Treasury securities 5 — — — 5 Residential CMOs — 7,531 — — 7,531 Residential MBS — 724 — — 724 Commercial MBS — 1,791 — — 1,791 Other agencies — 187 — — 187 Municipal securities — 604 3,230 — 3,834 Asset-backed securities — 427 — — 427 Corporate debt — 102 — — 102 Other securities/sovereign debt — 6 — — 6 5 11,372 3,230 — 14,607 Other securities 21 — — — 21 Loans held for sale — 426 — — 426 Loans held for investment — 49 37 — 86 MSRs — — 12 — 12 Derivative assets — 350 6 (269 ) 87 Liabilities Derivative liabilities — 433 6 (282 ) 157 Short-term borrowings 1 — — — 1 Fair Value Measurements at Reporting Date Using Netting Adjustments (1) December 31, 2017 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Other securities $ 83 $ 3 — — $ 86 83 3 — — 86 Available-for-sale securities: U.S. Treasury securities 5 — — — 5 Residential CMOs — 6,484 — — 6,484 Residential MBS — 1,367 — — 1,367 Commercial MBS — 2,487 — — 2,487 Other agencies — 70 — — 70 Municipal securities — 711 3,167 — 3,878 Asset-backed securities — 443 24 — 467 Corporate debt — 109 — — 109 Other securities/sovereign debt — 2 — — 2 5 11,673 3,191 — 14,869 Other securities 19 — — — 19 Loans held for sale — 413 — — 413 Loans held for investment — 55 38 — 93 MSRs — — 11 — 11 Derivative assets — 316 6 (190 ) 132 Liabilities Derivative liabilities — 326 5 (245 ) 86 (1) Amounts represent the impact of legally enforceable master netting agreements that allow the Company to settle positive and negative positions and cash collateral held or placed with the same counterparties.
Rollforward of financial instruments measured on a recurring basis and classified as Level 3	Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Opening balance $ 11 $ (1 ) $ 3,167 $ 24 $ 38 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — (5 ) — — — Total gains/losses for the period: Included in earnings 1 6 (1 ) (2 ) — Included in OCI — — (28 ) 11 — Purchases/originations — — 193 — — Sales — — — (33 ) — Repayments — — — — (1 ) Settlements — — (101 ) — — Closing balance $ 12 $ — $ 3,230 $ — $ 37 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ 1 $ — $ — $ — $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Opening balance $ 14 $ (2 ) $ 2,798 $ 76 $ 48 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — — — — — Total gains/losses for the period: Included in earnings (1 ) 5 (1 ) — — Included in OCI — — 20 3 — Purchases/originations — — 133 — — Sales — — (19 ) — Repayments — — — — (4 ) Settlements — — (82 ) (1 ) — Closing balance $ 13 $ 3 $ 2,868 $ 59 $ 44 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ 5 $ 20 $ 1 $ — (1) Transfers out of Level 3 represent the settlement value of the derivative instruments (i.e. interest rate lock agreements) that is transferred to loans held for sale, which is classified as Level 2.
Classification of gains and losses due to changes in fair value, recorded in earnings for Level 3 assets and liabilities	The tables below summarize the classification of gains and losses due to changes in fair value, recorded in earnings for Level 3 assets and liabilities for the three-month periods ended March 31, 2018 and 2017 : Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ 1 $ 6 $ — $ — $ — Securities gains (losses) — — — (2 ) — Other expense — — (1 ) — — Total $ 1 $ 6 $ (1 ) $ (2 ) $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ (1 ) $ 5 $ — $ — $ — Securities gains (losses) — — (1 ) — — Total $ (1 ) $ 5 $ (1 ) $ — $ —
Assets and liabilities under the fair value option	The following tables present the fair value and aggregate principal balance of certain assets and liabilities under the fair value option: March 31, 2018 (dollar amounts in millions) Total Loans Loans that are 90 or more days past due Assets Fair value carrying amount Aggregate unpaid principal Difference Fair value carrying amount Aggregate unpaid principal Difference Loans held for sale $ 426 $ 416 $ 10 $ 1 $ 1 $ — Loans held for investment 86 94 (8 ) 8 9 (1 ) December 31, 2017 (dollar amounts in millions) Total Loans Loans that are 90 or more days past due Assets Fair value carrying amount Aggregate unpaid principal Difference Fair value carrying amount Aggregate unpaid principal Difference Loans held for sale $ 413 $ 400 $ 13 $ 1 $ 1 $ — Loans held for investment 93 102 (9 ) 10 11 (1 ) The following tables present the net gains (losses) from fair value changes for the three-month periods ended March 31, 2018 and 2017 . Net gains (losses) from fair value changes (dollar amounts in millions) Three Months Ended Assets 2018 2017 Loans held for sale $ (2 ) $ 9 Loans held for investment — —
Assets measured at fair value on a nonrecurring basis	assets measured at fair value on a nonrecurring basis were as follows: Fair Value Measurements Using (dollar amounts in millions) Fair Value Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Other Unobservable Inputs (Level 3) Total Impaired loans 58 — — 58 — Other real estate owned 30 — — 30 —
Quantitative information about significant unobservable level 3 fair value measurement inputs	Quantitative Information about Level 3 Fair Value Measurements at March 31, 2018 (dollar amounts in millions) Fair Value Valuation Technique Significant Unobservable Input Range (Weighted Average) Measured at fair value on a recurring basis: MSRs $ 12 Discounted cash flow Constant prepayment rate 6% - 31% (9%) Spread over forward interest rate 5% - 11% (8%) Derivative assets 6 Consensus Pricing Net market price -5% - 20% (2%) Estimated Pull through % 0% - 100% (85%) Derivative liabilities 6 Discounted cash flow Estimated conversion factor 165% Estimated growth rate of Visa Class A shares 7% Discount rate 3% Timing of the resolution of the litigation 3/31/2018 - 06/30/2020 Municipal securities 3,230 Discounted cash flow Discount rate 0% - 9% (3%) Cumulative default 0% - 64% (3%) Loss given default 5% - 90% (25%) Loans held for investment 37 Discounted cash flow Discount rate 7% - 18% (8%) Constant prepayment rate 2% - 22% (8%) Measured at fair value on a nonrecurring basis: Impaired loans 58 Appraisal value NA NA Other real estate owned 30 Appraisal value NA NA Quantitative Information about Level 3 Fair Value Measurements at December 31, 2017 (dollar amounts in millions) Fair Value Valuation Technique Significant Unobservable Input Range (Weighted Average) Measured at fair value on a recurring basis: MSRs $ 11 Discounted cash flow Constant prepayment rate 8% - 33% (12%) Spread over forward interest rate 8% - 10% (8%) Derivative assets 6 Consensus Pricing Net market price -5% - 20% (2%) Estimated Pull through % 3% - 100% (75%) Derivative liabilities 5 Discounted cash flow Estimated conversion factor 165% Estimated growth rate of Visa Class A shares 7% Discount rate 3% Timing of the resolution of the litigation 12/31/2017 - 06/30/2020 Municipal securities 3,167 Discounted cash flow Discount rate 0% - 10% (4%) Cumulative default 0% - 64% (3%) Loss given default 5% - 90% (24%) Asset-backed securities 24 Discounted cash flow Discount rate 7% - 7% (7%) Cumulative prepayment rate 0% - 72% (7%) Cumulative default 3% - 53% (7%) Loss given default 90% - 100% (98%) Cure given deferral 50% - 50% (50%) Loans held for investment 38 Discounted cash flow Discount rate 7% - 18% (8%) Constant prepayment rate 2% - 22% (9%) Measured at fair value on a nonrecurring basis: MSRs 190 Discounted cash flow Constant prepayment rate 6% - 21% (8%) Spread over forward interest rate 2% - 20% (10%) Impaired loans 36 Appraisal value NA NA Other real estate owned 33 Appraisal value NA NA
Carrying amounts and estimated fair values of financial instruments	The following table provides the carrying amounts and estimated fair values of Huntington’s financial instruments at March 31, 2018 and December 31, 2017 : March 31, 2018 (dollar amounts in millions) Amortized Cost Lower of Cost or Market Fair Value or Fair Value Option Total Carrying Amount Estimated Fair Value Financial Assets Cash and short-term assets 1,115 — — 1,115 1,115 Trading account securities — — 85 85 85 Available-for-sale securities — — 14,607 14,607 14,607 Held-to-maturity securities 8,789 — — 8,789 8,550 Other securities 581 — 21 602 602 Loans held for sale — 80 426 506 510 Net loans and direct financing leases (1) 70,356 — 86 70,442 69,820 Derivatives — — 87 87 87 Financial Liabilities Deposits 79,471 — — 79,471 79,425 Short-term borrowings 2,854 — — 2,854 2,854 Long-term debt 8,618 — — 8,618 8,771 Derivatives — — 157 157 157 (1) Includes collateral-dependent loans measured for impairment. December 31, 2017 (dollar amounts in millions) Amortized Cost Lower of Cost or Market Fair Value or Fair Value Option Total Carrying Amount Estimated Fair Value Financial Assets Cash and short-term assets 1,567 — — $ 1,567 $ 1,567 Trading account securities — — 86 86 86 Available-for-sale securities — — 14,869 14,869 14,869 Held-to-maturity securities 9,091 — — 9,091 8,971 Other securities 581 — 19 600 600 Loans held for sale — 75 413 488 491 Net loans and direct financing leases (1) 69,333 — 93 69,426 69,146 Derivatives — — 132 132 132 Financial Liabilities Deposits 77,041 — — 77,041 77,010 Short-term borrowings 5,056 — — 5,056 5,056 Long-term debt 9,206 — — 9,206 9,402 Derivatives — — 86 86 86 (1) Includes collateral-dependent loans measured for impairment. The following table presents the level in the fair value hierarchy for the estimated fair values at March 31, 2018 and December 31, 2017 : Estimated Fair Value Measurements at Reporting Date Using March 31, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 82 $ 3 $ — $ 85 Available-for-sale securities 5 11,372 3,230 14,607 Held-to-maturity securities — 8,550 — 8,550 Other securities 21 — — 21 Loans held for sale — 426 84 510 Net loans and direct financing leases — — 69,820 69,820 Financial Liabilities Deposits — 74,573 4,852 79,425 Short-term borrowings 1 — 2,853 2,854 Long-term debt — 8,299 472 8,771 Estimated Fair Value Measurements at Reporting Date Using December 31, 2017 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 83 $ 3 $ — $ 86 Available-for-sale securities 5 11,673 3,191 14,869 Held-to-maturity securities — 8,971 — 8,971 Other securities 19 — — 19 Loans held for sale — 413 78 491 Net loans and direct financing leases — — 69,146 69,146 Financial Liabilities Deposits — 73,975 3,035 77,010 Short-term borrowings — — 5,056 5,056 Long-term debt — 8,944 458 9,402

DERIVATIVE FINANCIAL INSTRUME38

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gross notional values of derivatives used in asset and liability management activities	The following table presents the gross notional values of derivatives used in Huntington’s asset and liability management activities at March 31, 2018 and December 31, 2017 , identified by the underlying interest rate-sensitive instruments. March 31, 2018 (dollar amounts in millions) Fair Value Hedges Cash Flow Hedges Total Instruments associated with: Investment securities — 12 $ 12 Subordinated notes 950 — 950 Long-term debt 6,890 — 6,890 Total notional value at March 31, 2018 $ 7,840 $ 12 $ 7,852 December 31, 2017 (dollar amounts in millions) Fair Value Hedges Cash Flow Hedges Total Instruments associated with: Subordinated notes 950 — 950 Long-term debt 7,425 — 7,425 Total notional value at December 31, 2017 $ 8,375 $ — $ 8,375
Additional information about the interest rate swaps used in asset and liability management activities	The following table presents additional information about the interest rate swaps used in Huntington’s asset and liability management activities at March 31, 2018 and December 31, 2017 . March 31, 2018 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Asset conversion swaps Receive fixed—generic $ 12 2.0 $ — 2.20 % 1.78 % Liability conversion swaps Receive fixed—generic 7,840 2.4 (176 ) 1.57 1.88 Total swap portfolio at March 31, 2018 $ 7,852 2.4 $ (176 ) December 31, 2017 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Liability conversion swaps Receive fixed—generic 8,375 2.5 (99 ) 1.56 1.44 Total swap portfolio at December 31, 2017 $ 8,375 2.5 $ (99 )
Asset and liability derivatives included in accrued income and other assets	March 31, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Derivatives designated as Hedging Instruments Interest rate contracts $ 15 $ 191 $ 22 $ 121 Derivatives not designated as Hedging Instruments Interest rate contracts (1) 228 138 187 100 Foreign exchange contracts 20 22 18 18 Commodities contracts 89 83 92 87 Equity contracts 4 5 3 5 Total Contracts $ 356 $ 439 $ 322 $ 331
Increase or (decrease) to interest expense for derivatives designated as fair value hedges	The following table presents the change in fair value for derivatives designated as fair value hedges as well as the offsetting change in fair value on the hedged item for the three-month periods ended March 31, 2018 and 2017 . Three Months Ended (dollar amounts in millions) 2018 2017 Interest rate contracts Change in fair value of interest rate swaps hedging subordinated notes (1) (17 ) (5 ) Change in fair value of hedged subordinated notes (1) 18 5 Change in fair value of interest rate swaps hedging other long-term debt (1) (51 ) (10 ) Change in fair value of hedged other long-term debt (1) 53 9 (1) Recognized in Interest expense—subordinated notes and other long-term debt in the Unaudited Condensed Consolidated Statements of Income.
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block]	As of March 31, 2018 , the following amounts were recorded on the balance sheet related to cumulative basis adjustments for fair value hedges. Carrying Amount of the Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment To Hedged Liabilities (dollar amounts in millions) March 31, 2018 March 31, 2018 Long-term debt $ 7,709 $ (186 ) Total $ 7,709 $ (186 ) The cumulative amount of fair value hedging adjustments remaining for any hedged assets and liabilities for which hedge accounting has been discontinued is less than $1 million at March 31, 2018.
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges	The following table presents the amount of gain or loss recognized in income for derivatives not designated as hedging instruments under ASC Subtopic 815-10 in the Unaudited Condensed Consolidated Income Statement for the three months ended March 31, 2018 . Location of Gain or (Loss) Recognized in Income on Derivative Amount of Gain or (Loss) Recognized in Income on Derivative (dollar amounts in millions) Three Months Ended March 31, 2018 Interest rate contracts: Customer Capital markets fees $ 7 MSR Mortgage banking income (8 ) Foreign exchange contracts Capital markets fees 6 Commodities contracts Capital markets fees 2 Equity contracts Other noninterest expense (1 ) Total $ 6 The following table presents the gains and (losses) recognized in OCI and the location in the Unaudited Condensed Consolidated Statements of Income of gains and (losses) reclassified from OCI into earnings for derivatives designated as effective cash flow hedges for the three-month periods ended March 31, 2018 and 2017 . Derivatives in cash flow hedging relationships Amount of gain or (loss) recognized in OCI on derivatives (effective portion) (after-tax) Location of gain or (loss) reclassified from accumulated OCI into earnings (effective portion) Amount of (gain) or loss reclassified from accumulated OCI into earnings (effective portion) Three Months Ended March 31, Three Months Ended March 31, (dollar amounts in millions) 2018 2017 2018 2017 Interest rate contracts Loans $ — $ (1 ) Interest and fee income - loans and leases $ — $ 1 Investment securities — — Noninterest income - other income — — Total $ — $ (1 ) $ — $ 1
Gains and (losses) recognized in noninterest income on the ineffective portion on interest rate contracts for derivatives designated as fair value and cash flow hedges
Derivative assets and liabilities used in mortgage banking activities [Table Text Block]	The following table summarizes the derivative assets and liabilities used in mortgage banking activities: Derivatives used in mortgage banking activities March 31, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Interest rate lock agreements $ 6 $ 1 $ 6 $ — Forward trades and options 2 2 1 — Total derivatives used in mortgage banking activities $ 8 $ 3 $ 7 $ —
Offsetting of financial liabilities and derivative liabilities	Offsetting of Financial Liabilities and Derivative Liabilities Gross amounts offset in the condensed consolidated balance sheets Net amounts of liabilities presented in the condensed consolidated balance sheets Gross amounts not offset in the condensed consolidated balance sheets (dollar amounts in millions) Gross amounts of recognized liabilities Financial instruments Cash collateral delivered Net amount March 31, 2018 Derivatives $ 439 $ (282 ) $ 157 $ — $ (21 ) $ 136 December 31, 2017 Derivatives 331 (245 ) 86 — (21 ) 65
Offsetting of financial assets and derivatives assets	The following tables present the gross amounts of these assets and liabilities with any offsets to arrive at the net amounts recognized in the Unaudited Condensed Consolidated Balance Sheets at March 31, 2018 and December 31, 2017 . Offsetting of Financial Assets and Derivative Assets Gross amounts Net amounts of Gross amounts not offset in the condensed consolidated balance sheets (dollar amounts in millions) Gross amounts of recognized assets Financial instruments Cash collateral received Net amount March 31, 2018 Derivatives $ 356 $ (269 ) $ 87 $ (2 ) $ (11 ) $ 74 December 31, 2017 Derivatives 322 (190 ) 132 (11 ) (18 ) 103

VIEs (Tables)

VIEs (Tables)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Carrying amount and classification of the trusts assets and liabilities	The following tables provide a summary of the assets and liabilities included in Huntington’s Unaudited Condensed Consolidated Financial Statements, as well as the maximum exposure to losses, associated with its interests related to unconsolidated VIEs for which Huntington holds an interest, but is not the primary beneficiary, to the VIE at March 31, 2018 , and December 31, 2017 : March 31, 2018 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 6 $ 1 $ 6 2015-1 Automobile Trust 1 — 1 Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 634 320 634 Other Investments 122 57 122 Total $ 777 $ 630 $ 763 December 31, 2017 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 7 $ — $ 7 2015-1 Automobile Trust 1 — 1 Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 636 335 636 Other Investments 117 53 117 Total $ 775 $ 640 $ 761
Summary of Outstanding Trust Preferred Securities	A list of trust preferred securities outstanding at March 31, 2018 follows: (dollar amounts in millions) Rate Principal amount of subordinated note/ debenture issued to trust (1) Investment in unconsolidated subsidiary Huntington Capital I 3.01 % (2) $ 70 $ 6 Huntington Capital II 2.94 (3) 32 3 Sky Financial Capital Trust III 3.71 (4) 72 2 Sky Financial Capital Trust IV 3.71 (4) 74 2 Camco Financial Trust 3.64 (5) 4 1 Total $ 252 $ 14 (1) Represents the principal amount of debentures issued to each trust, including unamortized original issue discount. (2) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 0.70% . (3) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 0.625% . (4) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 1.40% . (5) Variable effective rate at March 31, 2018 , based on three-month LIBOR + 1.33% .
Affordable housing tax credit investments	The following table presents the balances of Huntington’s affordable housing tax credit investments and related unfunded commitments at March 31, 2018 and December 31, 2017 . (dollar amounts in millions) March 31, December 31, Affordable housing tax credit investments $ 1,013 $ 996 Less: amortization (379 ) (360 ) Net affordable housing tax credit investments $ 634 $ 636 Unfunded commitments $ 320 $ 335 The following table presents other information relating to Huntington’s affordable housing tax credit investments for the three-month periods ended March 31, 2018 and 2017 . Three Months Ended (dollar amounts in millions) 2018 2017 Tax credits and other tax benefits recognized $ 23 $ 23 Proportional amortization method Tax credit amortization expense included in provision for income taxes 19 17

COMMITMENTS AND CONTINGENT LI40

COMMITMENTS AND CONTINGENT LIABILITIES (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contract amounts of various commitments to extend credit	In the ordinary course of business, Huntington makes various commitments to extend credit that are not reflected in the Unaudited Condensed Consolidated Financial Statements. The contract amounts of these financial agreements at March 31, 2018 and December 31, 2017 , were as follows: (dollar amounts in millions) March 31, December 31, Contract amount represents credit risk Commitments to extend credit: Commercial $ 16,265 $ 16,219 Consumer 14,353 13,384 Commercial real estate 1,323 1,366 Standby letters of credit 583 510 Commercial letters-of-credit 17 21

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Listed in the table below is certain operating basis financial information reconciled to Huntington’s March 31, 2018 , December 31, 2017 , and March 31, 2017 , reported results by business segment. Three Months Ended March 31, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 395 $ 220 $ 99 $ 45 $ 11 $ 770 Provision (benefit) for credit losses 31 21 14 — — 66 Noninterest income 174 69 3 51 17 314 Noninterest expense 412 120 35 58 8 633 Provision (benefit) for income taxes 26 31 11 8 (17 ) 59 Net income (loss) $ 100 $ 117 $ 42 $ 30 $ 37 $ 326 2017 Net interest income $ 375 $ 228 $ 104 $ 45 $ (22 ) $ 730 Provision (benefit) for credit losses 33 21 11 3 — 68 Noninterest income 171 64 5 48 24 312 Noninterest expense 413 117 36 63 78 707 Provision (benefit) for income taxes 35 54 22 10 (62 ) 59 Net income (loss) $ 65 $ 100 $ 40 $ 17 $ (14 ) $ 208 Assets at Deposits at (dollar amounts in millions) March 31, December 31, March 31, December 31, Consumer & Business Banking $ 26,346 $ 26,220 $ 47,124 $ 45,643 Commercial Banking 32,744 32,118 21,838 21,235 Vehicle Finance 18,138 17,865 345 358 RBHPCG 5,888 5,821 6,053 6,057 Treasury / Other 21,130 22,161 4,111 3,748 Total $ 104,246 $ 104,185 $ 79,471 $ 77,041
Segment Disclosure of Assets and Deposits	Assets at Deposits at (dollar amounts in millions) March 31, December 31, March 31, December 31, Consumer & Business Banking $ 26,346 $ 26,220 $ 47,124 $ 45,643 Commercial Banking 32,744 32,118 21,838 21,235 Vehicle Finance 18,138 17,865 345 358 RBHPCG 5,888 5,821 6,053 6,057 Treasury / Other 21,130 22,161 4,111 3,748 Total $ 104,246 $ 104,185 $ 79,471 $ 77,041

LOANS _ LEASES AND ALLOWANCE 42

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	3 Months Ended
	Mar. 31, 2018USD ($)reserve	Dec. 31, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable net premium	$ 359,000,000	$ 334,000,000
Consumer loans	86,000,000	93,000,000
Allowance for loan and lease losses	$ (721,000,000)	(691,000,000)	$ (673,000,000)	$ (638,000,000)
Number of days past due	30 days
Allowance number of reserves | reserve	2
Collateral for secured borrowings	$ 33,500,000,000	31,700,000,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan and lease losses	$ (515,000,000)	(482,000,000)	(480,000,000)	(451,000,000)
Threshold period past due for nonperforming status	90 days
Threshold outstanding balance for quarterly impairment evaluation	$ 1,000,000
Threshold period past due for write-off	90 days
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	$ 0	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan and lease losses	$ (206,000,000)	(209,000,000)	$ (193,000,000)	$ (187,000,000)
Threshold period past due for write-off	120 days
Consumer | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	$ 1,000,000	1,000,000
Consumer | Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	2,000,000	2,000,000
Consumer | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	82,000,000	89,000,000
Consumer | RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	1,000,000	1,000,000
Consumer | Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer loans	$ 0	$ 0

LOANS _ LEASES AND ALLOWANCE 43

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Loan and Lease Portfolio Composition (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial		$ 28,622	$ 28,107
Commercial real estate		7,412	7,225
Automobile		12,146	12,100
Home equity		9,987	10,099
Residential mortgage		9,357	9,026
Recreation Finance		2,549	2,438
Other consumer		1,090	1,122
Loans and leases	[1]	71,163	70,117
Allowance for loan and lease losses		(721)	(691)	$ (673)	$ (638)
Net loans and leases		70,442	69,426
Loans Receivable, Fair Value Disclosure		86	93
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile		12,145	12,099
Home equity		9,985	10,097
Residential mortgage		9,275	8,937
Other consumer		1,090	1,122
Allowance for loan and lease losses		(206)	(209)	(193)	(187)
Consumer | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		12,146	12,100
Loans Receivable, Fair Value Disclosure		1	1
Consumer | Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		9,987	10,099
Loans Receivable, Fair Value Disclosure		2	2
Consumer | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		9,357	9,026
Loans Receivable, Fair Value Disclosure		82	89
Consumer | RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		2,549	2,438
Loans Receivable, Fair Value Disclosure		1	1
Consumer | Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,090	1,122
Loans Receivable, Fair Value Disclosure		0	0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial		28,622	28,107
Commercial real estate		7,412	7,225
Allowance for loan and lease losses		(515)	(482)	$ (480)	$ (451)
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		28,622	28,107
Loans Receivable, Fair Value Disclosure		0	0
Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		7,412	7,225
Loans Receivable, Fair Value Disclosure		$ 0	$ 0
[1]	Amounts represent loans for which Huntington has elected the fair value option.

LOANS _ LEASES AND ALLOWANCE 44

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Certain Loans Acquired Ending and Unpaid Balances (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance		$ 41
Total ALLL balance	$ 721	691	$ 673	$ 638
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ALLL balance	$ 515	482	$ 480	$ 451
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance		$ 39

LOANS _ LEASES AND ALLOWANCE 45

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Nonaccrual Loans by Loan Class (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 383	$ 349
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	190	161
Commercial | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	30	29
Consumer | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	5	6
Consumer | Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	75	68
Consumer | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	82	84
Consumer | RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	1	1
Consumer | Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 0	$ 0

LOANS _ LEASES AND ALLOWANCE 46

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - NALs Past Due (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		$ 629	$ 714
Current		70,448	69,269
Purchased Credit Impaired			41
Consumer loans		86	93
Loans and leases	[1]	71,163	70,117
90 or more days past due and accruing		106	115
30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		279	335
60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		89	108
90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		261	271
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		117	114
Current		28,505	27,954
Purchased Credit Impaired			39
Consumer loans		0	0
Loans and leases		28,622	28,107
90 or more days past due and accruing		9	9
Commercial | Commercial and Industrial | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		39	35
Commercial | Commercial and Industrial | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		13	14
Commercial | Commercial and Industrial | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		65	65
Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		19	22
Current		7,393	7,201
Purchased Credit Impaired			2
Consumer loans		0	0
Loans and leases		7,412	7,225
90 or more days past due and accruing		1	3
Commercial | Real Estate | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		13	10
Commercial | Real Estate | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		0	1
Commercial | Real Estate | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		6	11
Consumer | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		87	117
Current		12,058	11,982
Purchased Credit Impaired			0
Consumer loans		1	1
Loans and leases		12,146	12,100
90 or more days past due and accruing		6	7
Consumer | Automobile | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		66	89
Consumer | Automobile | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		13	18
Consumer | Automobile | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		8	10
Consumer | Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		137	128
Current		9,848	9,969
Purchased Credit Impaired			0
Consumer loans		2	2
Loans and leases		9,987	10,099
90 or more days past due and accruing		15	18
Consumer | Home Equity | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		55	49
Consumer | Home Equity | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		20	19
Consumer | Home Equity | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		62	60
Consumer | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		241	295
Current		9,034	8,642
Purchased Credit Impaired			0
Consumer loans		82	89
Loans and leases		9,357	9,026
90 or more days past due and accruing		69	72
Consumer | Residential Mortgage | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		89	129
Consumer | Residential Mortgage | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		37	48
Consumer | Residential Mortgage | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		115	118
Consumer | RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		11	16
Current		2,537	2,421
Purchased Credit Impaired			0
Consumer loans		1	1
Loans and leases		2,549	2,438
90 or more days past due and accruing		2	1
Consumer | RV and Marine FInance | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		8	11
Consumer | RV and Marine FInance | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		2	3
Consumer | RV and Marine FInance | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		1	2
Consumer | Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		17	22
Current		1,073	1,100
Purchased Credit Impaired			0
Consumer loans		0	0
Loans and leases		1,090	1,122
90 or more days past due and accruing		4	5
Consumer | Other Consumer | 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		9	12
Consumer | Other Consumer | 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		4	5
Consumer | Other Consumer | 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due		$ 4	$ 5
[1]	Amounts represent loans for which Huntington has elected the fair value option.

LOANS _ LEASES AND ALLOWANCE 47

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision For (Reduction In Allowance) Unfunded Loan Commitments and Letters of Credit.	$ (2)	$ (6)
Portion of ALLL balance:
ALLL balance, beginning of period	691	638
Loan charge-offs	(73)	(70)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	35	31
Provision for credit losses	66	68
Provision For (Reduction In Allowance) Loan and Lease Losses.	68	74
ALLL balance, end of period	721	673
AULC Balance, beginning of period	87	98
AULC Balance, end of period	85	92
ACL balance, end of period	806	765
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision For (Reduction In Allowance) Unfunded Loan Commitments and Letters of Credit.	(2)	2
Portion of ALLL balance:
ALLL balance, beginning of period	482	451
Loan charge-offs	(23)	(24)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	20	18
Provision for credit losses	36	35
ALLL balance, end of period	515	480
AULC Balance, beginning of period	84	87
AULC Balance, end of period	82	89
ACL balance, end of period	597	569
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision For (Reduction In Allowance) Unfunded Loan Commitments and Letters of Credit.	0	(8)
Portion of ALLL balance:
ALLL balance, beginning of period	209	187
Loan charge-offs	(50)	(46)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	15	13
Provision for credit losses		39
Provision For (Reduction In Allowance) Loan and Lease Losses.	32
ALLL balance, end of period	206	193
AULC Balance, beginning of period	3	11
AULC Balance, end of period	3	3
ACL balance, end of period	$ 209	$ 196

LOANS _ LEASES AND ALLOWANCE 48

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Credit Quality Indicators (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	$ 28,622	$ 28,107
Commercial real estate	7,412	7,225
Automobile	12,146	12,100
Home equity	9,987	10,099
Residential mortgage	9,357	9,026
Other consumer	1,090	1,122
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	28,622	28,107
Commercial real estate	7,412	7,225
Commercial | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	26,719	26,268
Commercial real estate	7,049	6,909
Commercial | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	1,142	1,116
Commercial real estate	139	115
Commercial | OLEM
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	747	694
Commercial real estate	222	200
Commercial | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	14	29
Commercial real estate	2	1
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	12,145	12,099
Home equity	9,985	10,097
Residential mortgage	9,275	8,937
RV and marine finance	2,548	2,437
Other consumer	1,090	1,122
Consumer | Greater than 750
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	6,114	6,102
Home equity	6,247	6,352
Residential mortgage	5,976	5,697
RV and marine finance	1,529	1,433
Other consumer	408	428
Consumer | 650-749
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	4,338	4,312
Home equity	3,025	3,024
Residential mortgage	2,591	2,581
RV and marine finance	866	863
Other consumer	549	540
Consumer | Less Than 650
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	1,395	1,390
Home equity	631	617
Residential mortgage	621	605
RV and marine finance	104	96
Other consumer	96	143
Consumer | Other FICO score
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	298	295
Home equity	82	104
Residential mortgage	87	54
RV and marine finance	49	45
Other consumer	$ 37	$ 11

LOANS _ LEASES AND ALLOWANCE 49

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - ALLL Attributable to Loans by Portfolio Segment (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment	$ 676	$ 650
Attributable to loans individually evaluated for impairment	45	41
Total ALLL balance	721	691	$ 673	$ 638
Portion of loan and lease ending balance:
Collectively evaluated for impairment	69,797	68,760
Individually evaluated for impairment	1,280	1,223
Financing Receivable Evaluated For Impairment	71,077	70,024
Commercial
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment	479	450
Attributable to loans individually evaluated for impairment	36	32
Total ALLL balance	515	482	480	451
Portion of loan and lease ending balance:
Collectively evaluated for impairment	35,364	34,684
Individually evaluated for impairment	670	607
Financing Receivable Evaluated For Impairment	36,034	35,332
Consumer
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment	197	200
Attributable to loans individually evaluated for impairment	9	9
Total ALLL balance	206	209	$ 193	$ 187
Portion of loan and lease ending balance:
Collectively evaluated for impairment	34,433	34,076
Individually evaluated for impairment	610	616
Financing Receivable Evaluated For Impairment	$ 35,043	34,692
Purchased credit-impaired
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment		0
Portion of loan and lease ending balance:
Collectively evaluated for impairment		41
Purchased credit-impaired | Commercial
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment		0
Portion of loan and lease ending balance:
Collectively evaluated for impairment		41
Purchased credit-impaired | Consumer
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment		0
Portion of loan and lease ending balance:
Collectively evaluated for impairment		$ 0

LOANS _ LEASES AND ALLOWANCE 50

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	$ 0	$ 0
Average balance of impaired loans with no allowance recorded	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	0	0
Average balance of impaired loans with no allowance recorded	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	0	0
Average balance of impaired loans with no allowance recorded	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0
RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	0
Average balance of impaired loans with no allowance recorded	0
Interest income recognized on impaired loans with no allowance recorded	0
Commercial | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	243	284
Unpaid principal balance of impaired loans with no allowance recorded	271	311
Average balance of impaired loans with no allowance recorded	264	276
Interest income recognized on impaired loans with no allowance recorded	5	4
Ending balance of impaired loans with allowance recorded	314	257
Unpaid principal balance of impaired loans with allowance recorded	349	280
Related Allowance	34	29
Impaired Financing Receivable, Average Recorded Investment	550	610
Impaired Financing Receivable, Interest Income, Accrual Method	8	6
Average balance of impaired loans with allowance recorded	286	334
Interest income recognized on impaired loans with allowance recorded	3	2
Loans considered impaired due to status as a TDR	399	382
Impaired Financing Receivable, Recorded Investment	557	541
Impaired Financing Receivable, Unpaid Principal Balance	620	591
Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	71	56
Unpaid principal balance of impaired loans with no allowance recorded	91	81
Average balance of impaired loans with no allowance recorded		86
Interest income recognized on impaired loans with no allowance recorded		2
Ending balance of impaired loans with allowance recorded	42
Unpaid principal balance of impaired loans with allowance recorded	48
Related Allowance	2
Loans considered impaired due to status as a TDR	92	93
Impaired Financing Receivable, Recorded Investment	113
Impaired Financing Receivable, Unpaid Principal Balance	139
Commercial | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average balance of impaired loans with no allowance recorded	63
Interest income recognized on impaired loans with no allowance recorded	2
Ending balance of impaired loans with allowance recorded		51
Unpaid principal balance of impaired loans with allowance recorded		51
Related Allowance		3
Impaired Financing Receivable, Average Recorded Investment	110	155
Impaired Financing Receivable, Interest Income, Accrual Method	2	2
Average balance of impaired loans with allowance recorded	47	69
Interest income recognized on impaired loans with allowance recorded	0	0
Impaired Financing Receivable, Recorded Investment		107
Impaired Financing Receivable, Unpaid Principal Balance		132
Consumer | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0	0
Ending balance of impaired loans with allowance recorded	37	36
Unpaid principal balance of impaired loans with allowance recorded	41	40
Related Allowance	2	2
Impaired Financing Receivable, Average Recorded Investment	36	32
Impaired Financing Receivable, Interest Income, Accrual Method	1	1
Average balance of impaired loans with allowance recorded	36	32
Interest income recognized on impaired loans with allowance recorded	1	1
Impaired Financing Receivable, Recorded Investment	37	36
Impaired Financing Receivable, Unpaid Principal Balance	41	40
Consumer | Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0	0
Ending balance of impaired loans with allowance recorded	335	334
Unpaid principal balance of impaired loans with allowance recorded	386	385
Related Allowance	14	14
Impaired Financing Receivable, Average Recorded Investment	334	323
Impaired Financing Receivable, Interest Income, Accrual Method	3	4
Average balance of impaired loans with allowance recorded	334	323
Interest income recognized on impaired loans with allowance recorded	3	4
Impaired Financing Receivable, Recorded Investment	335	334
Impaired Financing Receivable, Unpaid Principal Balance	386	385
Consumer | Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0	0
Ending balance of impaired loans with allowance recorded	307	308
Unpaid principal balance of impaired loans with allowance recorded	335	338
Related Allowance	4	4
Impaired Financing Receivable, Average Recorded Investment	308	339
Impaired Financing Receivable, Interest Income, Accrual Method	3	3
Average balance of impaired loans with allowance recorded	308	339
Interest income recognized on impaired loans with allowance recorded	3	3
Impaired Financing Receivable, Recorded Investment	307	308
Impaired Financing Receivable, Unpaid Principal Balance	335	338
Consumer | RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0	0
Unpaid principal balance of impaired loans with no allowance recorded		0
Average balance of impaired loans with no allowance recorded		0
Interest income recognized on impaired loans with no allowance recorded		0
Ending balance of impaired loans with allowance recorded	2	2
Unpaid principal balance of impaired loans with allowance recorded	3	3
Related Allowance	0	0
Impaired Financing Receivable, Average Recorded Investment	2	0
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Average balance of impaired loans with allowance recorded	2	0
Interest income recognized on impaired loans with allowance recorded	0	0
Impaired Financing Receivable, Recorded Investment	2	2
Impaired Financing Receivable, Unpaid Principal Balance	3	3
Consumer | Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0	0
Unpaid principal balance of impaired loans with no allowance recorded	0	0
Average balance of impaired loans with no allowance recorded	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0
Ending balance of impaired loans with allowance recorded	6	8
Unpaid principal balance of impaired loans with allowance recorded	6	8
Related Allowance	2	2
Impaired Financing Receivable, Average Recorded Investment	7	4
Impaired Financing Receivable, Interest Income, Accrual Method	0	0
Average balance of impaired loans with allowance recorded	7	4
Interest income recognized on impaired loans with allowance recorded	0	0
Impaired Financing Receivable, Recorded Investment	6	8
Impaired Financing Receivable, Unpaid Principal Balance	$ 6	$ 8

LOANS _ LEASES AND ALLOWANCE 51

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - TDRs (Details)	3 Months Ended
	Mar. 31, 2018USD ($)contract	Mar. 31, 2017USD ($)contract
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	1,603	1,428
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 153,000,000	$ 180,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 3,000,000	$ 2,000,000
Commercial | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts	1	1
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0
Commercial | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract		236
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	96,000,000	$ 113,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 2,000,000	$ 1,000,000
Commercial | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	2	3
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Commercial | Commercial and Industrial
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	241	240
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 96,000,000	$ 113,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 2,000,000	$ 1,000,000
Commercial | Commercial and Industrial | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	238
Commercial | Commercial Real Estate
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	48	24
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 32,000,000	$ 31,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Commercial | Commercial Real Estate | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Commercial | Commercial Real Estate | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	48	24
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 32,000,000	$ 31,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Commercial | Commercial Real Estate | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Automobile
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	627	731
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 6,000,000	$ 6,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Automobile | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	16	14
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Automobile | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	411	477
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 4,000,000	$ 4,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Automobile | Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	200	240
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 2,000,000	$ 2,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Automobile | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Home Equity
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	144	259
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 8,000,000	$ 13,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 1,000,000	$ 0
Consumer | Home Equity | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	1	8
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Home Equity | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	85	106
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 5,000,000	$ 5,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 1,000,000	$ 1,000,000
Consumer | Home Equity | Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	51	87
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 3,000,000	$ 4,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ (1,000,000)
Consumer | Home Equity | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	7	58
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 4,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Residential Mortgage
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	83	141
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 9,000,000	$ 16,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 1,000,000
Consumer | Residential Mortgage | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	2
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Residential Mortgage | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	72	99
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 9,000,000	$ 11,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 1,000,000
Consumer | Residential Mortgage | Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	10	24
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 3,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Residential Mortgage | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	1	16
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 2,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | RV and Marine FInance
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	19	29
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | RV and Marine FInance | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | RV and Marine FInance | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	3	14
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | RV and Marine FInance | Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	16	15
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | RV and Marine FInance | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Other Consumer
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	441	4
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 2,000,000	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Other Consumer | Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	440	1
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 2,000,000	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Other Consumer | Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	2
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Other Consumer | Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	1	1
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0
Consumer | Other Consumer | Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts | contract	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0

AVAILABLE-FOR-SALE SECURITIES -

AVAILABLE-FOR-SALE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Held To Maturity Securities Transferred To Available For Sale	$ 3,000
Available For Sale Securities Transferred To Held To Maturity Securities	3,000
Pledged investment securities to secure public and trust deposits, trading account liabilities, US Treasury demand notes and security repurchase agreements	7,000		$ 6,000
Unrealized Net Gains Recognized In OCI At Time Of Transfer Of Available For Sale Securities Transferred To Held To Maturity Securities	26
Unrealized Net Losses Recognized In OCI At Time Of Transfer Of Available For Sale Securities Transferred To Held To Maturity Securities	56
Commercial
Schedule of Available-for-sale Securities [Line Items]
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	$ 3	$ 3

AVAILABLE-FOR-SALE SECURITIES53

AVAILABLE-FOR-SALE SECURITIES - Contractual Maturities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	$ 6,804	$ 5,545
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	145	61
Over 12 Months	6,345	6,728
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	271	225
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	13,149	12,273
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(416)	(286)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost	15,005	15,127
Unrealized Gross Gains	18	28
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(416)	(286)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale securities	14,607	14,869
U.S. Treasury
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	5	5
Amortized Cost	5	5
Unrealized Gross Gains	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	5	5
Available-for-sale securities	5	5
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	3,291	1,660
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	71	19
Over 12 Months	4,027	4,520
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	188	159
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	7,318
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(259)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, 1-5 years	1	1
Amortized Cost, 6-10 years	47	90
Amortized Cost, Over 10 years	7,742	6,570
Amortized Cost	7,790	6,661
Unrealized Gross Gains	0	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(259)	(178)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	1	1
Fair Value, 6-10 years	45	89
Fair Value, Over 10 years	7,485	6,394
Available-for-sale securities	7,531	6,484
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	648	1,078
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	16	5
Over 12 Months	11	11
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	659	1,089
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(16)	(5)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, 1-5 years	6	6
Amortized Cost, 6-10 years	33	7
Amortized Cost, Over 10 years	700	1,358
Amortized Cost	739	1,371
Unrealized Gross Gains	2	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(16)	(5)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	5	6
Fair Value, 6-10 years	33	8
Fair Value, Over 10 years	686	1,353
Available-for-sale securities	724	1,367
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	322	960
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9	15
Over 12 Months	1,469	1,527
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	54	37
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,791	2,487
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(63)	(52)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, 1-5 years	69	23
Amortized Cost, 6-10 years	9	151
Amortized Cost, Over 10 years	1,775	2,365
Amortized Cost	1,853	2,539
Unrealized Gross Gains	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(63)	(52)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	67	22
Fair Value, 6-10 years	8	148
Fair Value, Over 10 years	1,716	2,317
Available-for-sale securities	1,791	2,487
Federal agencies: Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		6,180
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		(178)
Federal agencies, Other agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	107	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	0
Over 12 Months	69	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	176	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(3)	0
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	1	2
Amortized Cost, 1-5 years	8	9
Amortized Cost, 6-10 years	181	58
Amortized Cost	190	69
Unrealized Gross Gains	0	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(3)	0
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	1	2
Fair Value, 1-5 years	8	9
Fair Value, 6-10 years	178	59
Available-for-sale securities	187	70
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	4,368	3,737
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	97	39
Over 12 Months	5,576	6,058
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	244	196
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	9,944	9,795
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(341)	(235)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost	10,577	10,645
Unrealized Gross Gains	2	3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(341)	(235)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale securities	10,238	10,413
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	2,182	1,681
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	45	21
Over 12 Months	623	497
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	22	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,805	2,178
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(67)	(35)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	153	103
Amortized Cost, 1-5 years	1,129	1,140
Amortized Cost, 6-10 years	1,738	1,709
Amortized Cost, Over 10 years	867	940
Amortized Cost	3,887	3,892
Unrealized Gross Gains	14	21
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(67)	(35)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	153	103
Fair Value, 1-5 years	1,121	1,134
Fair Value, 6-10 years	1,717	1,704
Fair Value, Over 10 years	843	937
Available-for-sale securities	3,834	3,878
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	240	127
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	1
Over 12 Months	144	173
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	5	15
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	384	300
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(8)	(16)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, 1-5 years	80	80
Amortized Cost, 6-10 years	61	53
Amortized Cost, Over 10 years	294	349
Amortized Cost	435	482
Unrealized Gross Gains	0	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(8)	(16)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	79	80
Fair Value, 6-10 years	60	54
Fair Value, Over 10 years	288	333
Available-for-sale securities	427	467
Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0
Over 12 Months	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	1	0
Amortized Cost, 1-5 years	67	73
Amortized Cost, 6-10 years	19	20
Amortized Cost, Over 10 years	13	13
Amortized Cost	100	106
Unrealized Gross Gains	2	3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	1	0
Fair Value, 1-5 years	67	74
Fair Value, 6-10 years	20	21
Fair Value, Over 10 years	14	14
Available-for-sale securities	102	109
Other securities/Sovereign debt
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0
Over 12 Months	2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	2	1
Amortized Cost, 1-5 years	4	1
Amortized Cost	6	2
Unrealized Gross Gains	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	2	1
Fair Value, 1-5 years	4	1
Available-for-sale securities	$ 6	$ 2

AVAILABLE-FOR-SALE SECURITIES54

AVAILABLE-FOR-SALE SECURITIES - Schedule of Amortized Cost, Fair Value, and Gross Unrealized Gains and Losses (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 15,005	$ 15,127
Unrealized Gross Gains	18	28
Unrealized Gross Losses	(416)	(286)
Fair Value	14,607	14,869
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5	5
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	5	5
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,790	6,661
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(259)	(178)
Fair Value	7,531	6,484
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	739	1,371
Unrealized Gross Gains	2	1
Unrealized Gross Losses	(16)	(5)
Fair Value	724	1,367
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,853	2,539
Unrealized Gross Gains	0	0
Unrealized Gross Losses	(63)	(52)
Fair Value	1,791	2,487
Federal agencies, Other agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	190	69
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(3)	0
Fair Value	187	70
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,577	10,645
Unrealized Gross Gains	2	3
Unrealized Gross Losses	(341)	(235)
Fair Value	10,238	10,413
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,887	3,892
Unrealized Gross Gains	14	21
Unrealized Gross Losses	(67)	(35)
Fair Value	3,834	3,878
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	435	482
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(8)	(16)
Fair Value	427	467
Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	100	106
Unrealized Gross Gains	2	3
Unrealized Gross Losses	0	0
Fair Value	102	109
Other securities/Sovereign debt
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6	2
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	$ 6	$ 2

AVAILABLE-FOR-SALE SECURITIES A

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value
Less than 12 Months	$ 6,804	$ 5,545
Over 12 Months	6,345	6,728
Total	13,149	12,273
Gross Unrealized Losses
Less than 12 Months	(145)	(61)
Over 12 Months	(271)	(225)
Total	(416)	(286)
Federal agencies: Mortgage-backed securities
Fair Value
Total		6,180
Gross Unrealized Losses
Total		(178)
Collateralized Mortgage Obligations [Member]
Fair Value
Less than 12 Months	3,291	1,660
Over 12 Months	4,027	4,520
Total	7,318
Gross Unrealized Losses
Less than 12 Months	(71)	(19)
Over 12 Months	(188)	(159)
Total	(259)
Residential Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	648	1,078
Over 12 Months	11	11
Total	659	1,089
Gross Unrealized Losses
Less than 12 Months	(16)	(5)
Over 12 Months	0	0
Total	(16)	(5)
Commercial Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	322	960
Over 12 Months	1,469	1,527
Total	1,791	2,487
Gross Unrealized Losses
Less than 12 Months	(9)	(15)
Over 12 Months	(54)	(37)
Total	(63)	(52)
Federal agencies, Other agencies
Fair Value
Less than 12 Months	107	39
Over 12 Months	69	0
Total	176	39
Gross Unrealized Losses
Less than 12 Months	(1)	0
Over 12 Months	(2)	0
Total	(3)	0
Total U.S. Treasury, Federal agency and other agency securities
Fair Value
Less than 12 Months	4,368	3,737
Over 12 Months	5,576	6,058
Total	9,944	9,795
Gross Unrealized Losses
Less than 12 Months	(97)	(39)
Over 12 Months	(244)	(196)
Total	(341)	(235)
Municipal securities
Fair Value
Less than 12 Months	2,182	1,681
Over 12 Months	623	497
Total	2,805	2,178
Gross Unrealized Losses
Less than 12 Months	(45)	(21)
Over 12 Months	(22)	(14)
Total	(67)	(35)
Asset-backed securities
Fair Value
Less than 12 Months	240	127
Over 12 Months	144	173
Total	384	300
Gross Unrealized Losses
Less than 12 Months	(3)	(1)
Over 12 Months	(5)	(15)
Total	(8)	$ (16)
Corporate debt
Fair Value
Less than 12 Months	14
Over 12 Months	0
Total	14
Gross Unrealized Losses
Less than 12 Months	0
Over 12 Months	0
Total	0
Other securities/Sovereign debt
Fair Value
Less than 12 Months	0
Over 12 Months	2
Total	2
Gross Unrealized Losses
Less than 12 Months	0
Over 12 Months	0
Total	$ 0

AVAILABLE-FOR-SALE SECURITIES56

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Gross Realized Gains (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Gross gains on sales of securities	$ 5	$ 1
Gross (losses) on sales of securities	5	1
Net gain on sales of securities	0	0
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 0	$ 0

AVAILABLE-FOR-SALE SECURITIES57

AVAILABLE-FOR-SALE SECURITIES - Collateralized Debt Obligation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Unrealized Gross Losses	$ (416)	$ (286)
Collateralized Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gain (Loss) on Sale of Debt Investments	$ 3

AVAILABLE-FOR-SALE SECURITIES58

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Security Impairment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Impairment losses recognized in earnings on available-for-sale securities	$ 0	$ 0

HELD-TO-MATURITY SECURITIES - N

HELD-TO-MATURITY SECURITIES - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Held-to-maturity Securities [Abstract]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities	$ 0
Available For Sale Securities Transferred To Held To Maturity Securities	$ (2,833,000,000)	$ 0

HELD-TO-MATURITY SECURITIES - C

HELD-TO-MATURITY SECURITIES - Contractual Maturities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	$ 2,106	$ 1,416
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized Cost	8,789	9,091
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value	8,549	8,971
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	1,313	1,019
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, 6-10 years	39	0
Held-to-maturity Securities, Over 10 years	2,354	3,714
Amortized Cost	2,393	3,714
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 6-10 years	38	0
Fair Value, Over 10 years	2,291	3,657
Fair Value	2,329	3,657
Residential Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	0	0
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, 6-10 years	0	28
Held-to-maturity Securities, Over 10 years	1,651	1,021
Amortized Cost	1,651	1,049
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 6-10 years	0	28
Fair Value, Over 10 years	1,606	1,016
Fair Value	1,606	1,044
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	726	253
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, 1-5 years	0	38
Held-to-maturity Securities, 6-10 years	131	1
Held-to-maturity Securities, Over 10 years	4,223	3,752
Amortized Cost	4,354	3,791
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	0	37
Fair Value, 6-10 years	128	1
Fair Value, Over 10 years	4,101	3,698
Fair Value	4,229	3,736
Federal agencies, Other agencies
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	62	139
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, 1-5 years	14	7
Held-to-maturity Securities, 6-10 years	215	362
Held-to-maturity Securities, Over 10 years	157	163
Amortized Cost	386	532
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	13	8
Fair Value, 6-10 years	213	360
Fair Value, Over 10 years	154	161
Fair Value	380	529
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	2,101	1,411
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized Cost	8,784	9,086
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value	8,544	8,966
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	5	5
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, Over 10 years	5	5
Amortized Cost	5	5
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Over 10 years	5	5
Fair Value	$ 5	$ 5

HELD-TO-MATURITY SECURITIES - A

HELD-TO-MATURITY SECURITIES - Amortized Cost, Gross Unrealized Gains and Losses, & Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 8,451	$ 8,464
Amortized Cost	8,789	9,091
Unrealized Gross Gains	0	4
Unrealized Gross Losses	(239)	(124)
Fair Value	8,549	8,971
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	2,260	3,388
Amortized Cost	2,393	3,714
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(63)	(58)
Fair Value	2,329	3,657
Residential Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,606	974
Amortized Cost	1,651	1,049
Unrealized Gross Gains	0	2
Unrealized Gross Losses	(45)	(7)
Fair Value	1,606	1,044
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	4,221	3,709
Amortized Cost	4,354	3,791
Unrealized Gross Gains	0	0
Unrealized Gross Losses	(125)	(55)
Fair Value	4,229	3,736
Federal agencies, Other agencies
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	359	388
Amortized Cost	386	532
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(6)	(4)
Fair Value	380	529
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	8,446	8,459
Amortized Cost	8,784	9,086
Unrealized Gross Gains	0	4
Unrealized Gross Losses	(239)	(124)
Fair Value	8,544	8,966
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	5	5
Amortized Cost	5	5
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	$ 5	$ 5

HELD-TO-MATURITY SECURITIES -62

HELD-TO-MATURITY SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value
Less than 12 Months	$ 6,345	$ 7,048
Over 12 Months	2,106	1,416
Total	8,451	8,464
Gross Unrealized Losses
Less than 12 Months	(181)	(84)
Over 12 Months	(58)	(40)
Total	(239)	(124)
Collateralized Mortgage Obligations [Member]
Fair Value
Less than 12 Months	947	2,369
Over 12 Months	1,313	1,019
Total	2,260	3,388
Gross Unrealized Losses
Less than 12 Months	(23)	(26)
Over 12 Months	(40)	(32)
Total	(63)	(58)
Residential Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	1,606	974
Over 12 Months	0	0
Total	1,606	974
Gross Unrealized Losses
Less than 12 Months	(45)	(7)
Over 12 Months	0	0
Total	(45)	(7)
Commercial Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	3,495	3,456
Over 12 Months	726	253
Total	4,221	3,709
Gross Unrealized Losses
Less than 12 Months	(109)	(49)
Over 12 Months	(16)	(6)
Total	(125)	(55)
Federal agencies, Other agencies
Fair Value
Less than 12 Months	297	249
Over 12 Months	62	139
Total	359	388
Gross Unrealized Losses
Less than 12 Months	(4)	(2)
Over 12 Months	(2)	(2)
Total	(6)	(4)
Total U.S. Treasury, Federal agency and other agency securities
Fair Value
Less than 12 Months	6,345	7,048
Over 12 Months	2,101	1,411
Total	8,446	8,459
Gross Unrealized Losses
Less than 12 Months	(181)	(84)
Over 12 Months	(58)	(40)
Total	(239)	(124)
Municipal securities
Fair Value
Less than 12 Months	0	0
Over 12 Months	5	5
Total	5	5
Gross Unrealized Losses
Less than 12 Months	0	0
Over 12 Months	0	0
Total	$ 0	$ 0

OTHER SECURITIES (Details)

OTHER SECURITIES (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	$ 602	$ 600
Other Securities, Fair Value	602	600
Mutual Fund [Member]
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	19	18
Other Securities, Fair Value	19	18
Marketable equity securities
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	2	1
Other Securities, Fair Value	2	1
Investment in Federal Home Loan Bank Stock [Member] | Nonmarketable equity securities [Member]
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	287	287
Other Securities, Fair Value	287	287
Investment in Federal Reserve Stock [Member] | Nonmarketable equity securities [Member]
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	294	294
Other Securities, Fair Value	$ 294	$ 294

LOAN SALES AND SECURITIZATION64

LOAN SALES AND SECURITIZATIONS - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Residential Mortgage
Servicing Assets at Fair Value [Line Items]
Servicing income	$ 15	$ 14
Unpaid principal balance of third party serviced loans	20,100		$ 19,800
Automobile
Servicing Assets at Fair Value [Line Items]
Servicing income	3	5
Unpaid principal balance of third party serviced loans	900		1,000
Small Business Association (SBA) Loan
Servicing Assets at Fair Value [Line Items]
Servicing income	3	$ 3
Unpaid principal balance of third party serviced loans	$ 1,500		$ 1,400

LOAN SALES AND SECURITIZATION65

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio (Details) - Residential Mortgage - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Servicing Asset at Amortized Cost [Line Items]
Loans sold with servicing retained	$ 1	$ 1
Pretax gains resulting from above loan sales	$ 0	$ 0

LOAN SALES AND SECURITIZATION66

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Fair Value Method (Details) - Residential Mortgage - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Servicing Asset at Fair Value, Amount [Roll Forward]
Changes in valuation inputs or assumptions	$ 1	$ 1
Fair value, end of period:	$ 12	$ 13

LOAN SALES AND SECURITIZATION67

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 246		$ 238
Residential Mortgage
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	191	$ 172
New servicing assets created	10	10
Impairment recovery (charge)	(7)	(2)
Amortization and other	(8)	(6)
Carrying value, end of period	200	178
Fair value, end of period	$ 205	$ 179
Residential Mortgage | Amortization method
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Weighted-average life (years)	7 years	7 years 1 month

LOAN SALES AND SECURITIZATION68

LOAN SALES AND SECURITIZATIONS LOAN SALES AND SECURTIZIATIONS - Residential Mortgage Portfolio, MSRs Fair Value Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair value method | Residential Mortgage
Servicing Assets at Fair Value [Line Items]
Spread over forward interest rate swap rates, actual	0.00%	0.00%

LOAN SALES AND SECURITIZATION69

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Amortization Method Key Assumptions (Details) - Amortization method - Residential Mortgage - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Servicing Asset at Amortized Cost [Line Items]
Constant prepayment rate (annualized), actual	8.42%	8.30%
Constant prepayment rate (annualized), 10% adverse change	$ 0	$ 0
Constant prepayment rate (annualized), 20% adverse change	$ 0	$ 0
Spread over forward interest rate swap rates, actual	9.79%	10.49%
Spread over forward interest rate swap rates, 10% adverse change	$ 0	$ 0
Spread over forward interest rate swap rates, 20% adverse change	$ 0	$ 0

LOAN SALES AND SECURITIZATION70

LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 246		$ 238
Automobile
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	8	$ 18
Amortization and other	(2)	(3)
Fair value, end of period	7	15
Carrying value, end of period	$ 6	$ 15
Automobile | Amortization method
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Weighted-average life (years)	3 years 5 months	4 years

LOAN SALES AND SECURITIZATION71

LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortizations Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Amortization method | Automobile
Servicing Asset at Amortized Cost [Line Items]
Spread over forward interest rate swap rates, actual	0.00%	0.00%

LOAN SALES AND SECURITIZATION72

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio (Details) - Small Business Association (SBA) Loan - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Transfer of Financial Assets Accounted for as Sales [Line Items]
Loans with servicing retained sold	$ 64	$ 78
Pretax gains resulting from above loan sales	$ 7	$ 6

LOAN SALES AND SECURITIZATION73

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 246		$ 238
Small Business Association (SBA) Loan
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	27	$ 21
New servicing assets created	3	1
Amortization and other	(2)	(1)
Carrying value, end of period	28	21
Fair value, end of period	$ 32	$ 26
Weighted-average life (years)	3 years 3 months	3 years 4 months

LOAN SALES AND SECURITIZATION74

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio, MSRs Amortization Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Small Business Association (SBA) Loan | Amortization method
Servicing Asset at Amortized Cost [Line Items]
Spread over forward interest rate swap rates, actual	0.00%	0.00%

OTHER COMPREHENSIVE INCOME - Ac

OTHER COMPREHENSIVE INCOME - Activity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pretax
Other comprehensive income (loss), pretax	$ (190)	$ 15
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	42	(5)
After-tax
Other comprehensive income (loss), net of tax	(148)	10
Accumulated OTTI
Pretax
Other comprehensive income (loss), pretax	0	1
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	0	0
After-tax
Other comprehensive income (loss), net of tax	0	1
Unrealized gains and (losses) on debt securities | Debt Securities
Pretax
Other comprehensive income (loss), before reclassifications, before tax	(206)	9
Reclassification adjustment, before tax	15	6
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	45	(3)
Reclassification adjustment, tax	(3)	(2)
After-tax
Other comprehensive income (loss), before reclassifications, net of tax	(161)	6
Reclassification adjustment, net of tax	12	4
Other comprehensive income (loss), net of tax	(149)	11
Unrealized gains and (losses) on debt securities and Accumulated OTTI | Debt Securities
Pretax
Other comprehensive income (loss), pretax	(191)	16
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	42	(5)
Unrealized gains and (losses) on cash flow hedging derivatives
Pretax
Other comprehensive income (loss), before reclassifications, before tax		(2)
Reclassification adjustment, before tax		1
Other comprehensive income (loss), pretax		(1)
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax		1
Reclassification adjustment, tax		(1)
Total other comprehensive income (loss), tax (expense) benefit		0
After-tax
Other comprehensive income (loss), before reclassifications, net of tax		(1)
Reclassification adjustment, net of tax		0
Other comprehensive income (loss), net of tax		(1)
Unrealized gains (losses) for pension and other post- retirement obligations
Pretax
Other comprehensive income (loss), pretax	1	0
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	0	0
After-tax
Other comprehensive income (loss), net of tax	$ 1	$ 0

OTHER COMPREHENSIVE INCOME OTHE

OTHER COMPREHENSIVE INCOME OTHER COMPREHENSIVE INCOME - AOCI Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	$ 10,814	$ 10,308	$ 10,308
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	1
Other comprehensive income before reclassifications	(161)	6
Amounts reclassified from accumulated OCI to earnings	13	4
Period change		10
Balance, end of period	11,308	10,437	10,814
Unrealized gains and (losses) on debt securities | Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(278)	(193)	(193)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	(1)
Other comprehensive income before reclassifications	(161)	7
Amounts reclassified from accumulated OCI to earnings	12	4
Period change	(149)	11
Balance, end of period	(428)	(182)	(278)
Unrealized gains and (losses) on cash flow hedging derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	0	(3)	(3)
Other comprehensive income before reclassifications	0	(1)
Amounts reclassified from accumulated OCI to earnings	0	0
Period change	0	(1)
Balance, end of period	0	(4)	0
Unrealized gains (losses) for pension and other post- retirement obligations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(250)	(205)	(205)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated OCI to earnings	1	0
Period change	1	0
Balance, end of period	(249)	(205)	(250)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(528)	(401)	(401)
Period change	(148)
Balance, end of period	(677)	(391)	(528)
Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net unrealized loss on securities transfer	$ (147)	$ 81	$ (95)

OTHER COMPREHENSIVE INCOME - Re

OTHER COMPREHENSIVE INCOME - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest income - held-to-maturity securities - taxable	$ 54	$ 45
Noninterest income - net gains (losses) on sale of securities	0	0
Interest income - loans and leases	756	676
Noninterest income - other income	42	46
Noninterest expense - personnel costs	(376)	(382)
Income before income taxes	385	267
Provision for income taxes	(59)	(59)
Net income applicable to common shares	314	189
Unrealized gains and (losses) on debt securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest income - held-to-maturity securities - taxable	(3)	(4)
Noninterest income - net gains (losses) on sale of securities	(12)	(2)
Accumulated OTTI | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Noninterest income - net gains (losses) on sale of securities	0	0
Unrealized gains and (losses) on debt securities and Accumulated OTTI | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	(15)	(6)
Provision for income taxes	3	2
Net income applicable to common shares	(12)	(4)
Unrealized gains and (losses) on cash flow hedging derivatives | Interest Rate Contract [Member] | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest income - loans and leases	0	(1)
Income before income taxes	0	(1)
Provision for income taxes	0	1
Net income applicable to common shares	0	0
Amortization of defined benefit pension and post-retirement items: actuarial gains (losses) | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Noninterest expense - personnel costs	2	(1)
Amortization of defined benefit pension and post-retirement items: Prior service credit | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Noninterest expense - personnel costs	(1)	1
Unrealized gains (losses) for pension and other post- retirement obligations | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	1	0
Provision for income taxes	0	0
Net income applicable to common shares	$ 1	$ 0

SHAREHOLDERS' EQUITY (Details)

SHAREHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Millions	Aug. 16, 2016	Mar. 31, 2018	Feb. 27, 2018	Feb. 22, 2018	Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding		740,500			1,098,006
Preferred Stock, Value, Outstanding		$ 1,203
Preferred Stock, Value, Issued		$ 1,203			$ 1,071
Series A Preferred Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividend Payment Rate, Variable		.0850
Series B Preferred Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding		35,500
Preferred Stock, Value, Outstanding		$ 23
Preferred Stock, Dividend Payment Rate, Variable		3-mo. LIBOR + 270 bps
Preferred Stock, Redemption Date		Jan. 15, 2017
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Share Price				$ 15.73
Preferred Class A [Member]
Equity, Class of Treasury Stock [Line Items]
Convertible Preferred Stock, Threshold Percentage of Stock Price Trigger		130.00%
Convertible Preferred Stock Threshold of Stock Price Trigger				$ 11.95
Convertible Preferred Stock, Shares Issued upon Conversion				83.668
Series C Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding		100,000
Preferred Stock, Value, Outstanding		$ 100
Preferred Stock, Dividend Payment Rate, Variable		.05875
Preferred Stock, Redemption Date		Jan. 15, 2022
Preferred Stock, Redemption Period	90 days
Series E Preferred Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share			$ 100,000
Depositary Shares, Liquidation Preference Per Share			$ 1,000
Preferred Stock, Shares Outstanding		5,000
Preferred Stock, Value, Outstanding		$ 495
Preferred Stock, Dividend Payment Rate, Variable		0.057
Preferred Stock, Value, Issued			$ 500
Depositary Shares, Issued		500,000
Preferred Stock, Par or Stated Value Per Share			$ 0.01
Payments of Stock Issuance Costs		$ 5
Preferred Stock, Redemption Date		Apr. 15, 2023
Series D Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding		400,000
Preferred Stock, Value, Outstanding		$ 386
Preferred Stock, Dividend Payment Rate, Variable		.0625
Preferred Stock, Redemption Date		Jul. 15, 2021
Series D Preferred Stock2 [Member]
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding		200,000
Preferred Stock, Value, Outstanding		$ 199

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic earnings per common share:
Net income	$ 326	$ 208
Preferred stock dividends	(12)	(19)
Net income available to common shareholders	314	189
Effect of assumed preferred stock conversion	0	0
Net income applicable to diluted earnings per share	$ 314	$ 189
Average common shares issued and outstanding (in shares)	1,083,836	1,086,374
Basic earnings per common share (in usd per share)	$ 0.29	$ 0.17
Dilutive potential common shares:
Stock options and restricted stock units and awards	19,858	19,139
Shares held in deferred compensation plans	3,228	2,953
Dilutive impact of Preferred Stock	17,856	0
Other	0	151
Dilutive potential common shares	40,942	22,243
Total diluted average common shares issued and outstanding (in shares)	1,124,778	1,108,617
Diluted earnings per common share (in usd per share)	$ 0.28	$ 0.17
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options outstanding to purchase common stock shares having antidilutive effect	100	900

NON-INTEREST INCOME - Summary o

NON-INTEREST INCOME - Summary of Noninterest Income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenue from Contract with Customer [Abstract]
Noninterest income from contracts with customers	$ 214
Other noninterest income	100
Total noninterest income	$ 314	$ 312

NON-INTEREST INCOME - Disaggreg

NON-INTEREST INCOME - Disaggregation by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	$ 214
Other noninterest income	100
Noninterest income	314	$ 312
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	86
Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	49
Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	44
Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	21
Other Income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	14
Operating Segments | Consumer And Business Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	140
Other noninterest income	34
Noninterest income	174	171
Operating Segments | Consumer And Business Banking [Member] | Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	68
Operating Segments | Consumer And Business Banking [Member] | Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	47
Operating Segments | Consumer And Business Banking [Member] | Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	7
Operating Segments | Consumer And Business Banking [Member] | Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	8
Operating Segments | Consumer And Business Banking [Member] | Other Income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	10
Operating Segments | Commercial Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	20
Other noninterest income	49
Noninterest income	69	64
Operating Segments | Commercial Banking [Member] | Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	16
Operating Segments | Commercial Banking [Member] | Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2
Operating Segments | Commercial Banking [Member] | Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Operating Segments | Commercial Banking [Member] | Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Operating Segments | Commercial Banking [Member] | Other Income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Operating Segments | Vehicle Finance [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2
Other noninterest income	1
Noninterest income	3	5
Operating Segments | Vehicle Finance [Member] | Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Operating Segments | Vehicle Finance [Member] | Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Operating Segments | Vehicle Finance [Member] | Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Operating Segments | Vehicle Finance [Member] | Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Operating Segments | Vehicle Finance [Member] | Other Income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Operating Segments | Regional Banking and The Huntington Private Client Group [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	51
Other noninterest income	0
Noninterest income	51	48
Operating Segments | Regional Banking and The Huntington Private Client Group [Member] | Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Operating Segments | Regional Banking and The Huntington Private Client Group [Member] | Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Operating Segments | Regional Banking and The Huntington Private Client Group [Member] | Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	36
Operating Segments | Regional Banking and The Huntington Private Client Group [Member] | Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	11
Operating Segments | Regional Banking and The Huntington Private Client Group [Member] | Other Income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	3
Treasury / Other
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Other noninterest income	16
Noninterest income	17	$ 24
Treasury / Other | Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Treasury / Other | Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Treasury / Other | Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0
Treasury / Other | Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1
Treasury / Other | Other Income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	$ 0

BENEFIT PLANS - Narrative (Deta

BENEFIT PLANS - Narrative (Details)	3 Months Ended
	Mar. 31, 2018year
Defined Contribution Plan [Abstract]
Match - Base pay contributed to the plan	matches participant contributions, up to the first 5%
Post Retirement Benefits
Benefit Plans (Textuals) [Abstract]
Employees retirement age for health care and life insurance benefits under unfunded defined benefit post-retirement plan	55
Deferred Compensation Arrangement With Individual Requisite Service Period	10 years

BENEFIT PLANS - Net Periodic Be

BENEFIT PLANS - Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits
Components of net periodic benefit expense [Abstract]
Service cost	$ 1	$ 1
Interest cost	7	7
Expected return on plan assets	(12)	(14)
Amortization of prior service cost	0	0
Amortization of gain (loss)	2	2
Settlements	3	3
Net periodic (benefit) cost	1	(1)
Post Retirement Benefits
Components of net periodic benefit expense [Abstract]
Service cost	0	0
Interest cost	0	0
Expected return on plan assets	0	0
Amortization of prior service cost	(1)	0
Amortization of gain (loss)	0	0
Settlements	0	0
Net periodic (benefit) cost	$ (1)	$ 0

BENEFIT PLANS - Costs of Retire

BENEFIT PLANS - Costs of Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 11	$ 11

FAIR VALUES OF ASSETS AND LIA85

FAIR VALUES OF ASSETS AND LIABILITIES - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 426	$ 413
Loans Receivable, Fair Value Disclosure	$ 86	$ 93

FAIR VALUES OF ASSETS AND LIA86

FAIR VALUES OF ASSETS AND LIABILITIES - Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	$ 426,000	$ 413,000
Consumer loans	86,000	93,000
Trading account securities	85,000	86,000
Available-for-sale securities	14,607,000	14,869,000
Other Securities, Fair Value	602,000	600,000
Gross amounts of recognized assets	356,000	322,000
Derivative assets netting	(269,000)	(190,000)
Net amounts of assets presented in the condensed consolidated balance sheets	87,000	132,000
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	439,000	331,000
Gross amounts offset in the condensed consolidated balance sheets	(282,000)	(245,000)
Derivative liabilities	157,000	86,000
U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	5,000	5,000
Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	187,000	70,000
Municipal securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	3,834,000	3,878,000
Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	427,000	467,000
Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	102,000	109,000
Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	724,000	1,367,000
Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,791,000	2,487,000
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	426,000	413,000
Trading account securities	85,000	86,000
Available-for-sale securities	14,607,000	14,869,000
Other Securities, Fair Value	21,000	19,000
MSRs	12,000	11,000
Derivative assets netting	(269,000)	(190,000)
Net amounts of assets presented in the condensed consolidated balance sheets	87,000	132,000
Liabilities measured at fair value on a recurring basis
Gross amounts offset in the condensed consolidated balance sheets	(282,000)	(245,000)
Derivative liabilities	157,000	86,000
Short-term borrowings	1,000
Fair Value, Measurements, Recurring | U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	5,000	5,000
Fair Value, Measurements, Recurring | Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	7,531,000	6,484,000
Fair Value, Measurements, Recurring | Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	187,000	70,000
Fair Value, Measurements, Recurring | Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	2,000
Available-for-sale securities	3,834,000	3,878,000
Fair Value, Measurements, Recurring | Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	427,000	467,000
Fair Value, Measurements, Recurring | Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	102,000	109,000
Fair Value, Measurements, Recurring | Other Debt Obligations [Member]
Assets measured at fair value on a recurring basis
Trading account securities	83,000	86,000
Available-for-sale securities	6,000	2,000
Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	724,000	1,367,000
Fair Value, Measurements, Recurring | Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,791,000	2,487,000
Fair Value, Measurements, Recurring | Level 1
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	0	0
Consumer loans	0	0
Trading account securities	82,000	83,000
Available-for-sale securities	5,000	5,000
Other Securities, Fair Value	21,000	19,000
MSRs	0	0
Gross amounts of recognized assets	0	0
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	0	0
Short-term borrowings	1,000
Fair Value, Measurements, Recurring | Level 1 | U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	5,000	5,000
Fair Value, Measurements, Recurring | Level 1 | Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	0
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Other Debt Obligations [Member]
Assets measured at fair value on a recurring basis
Trading account securities	82,000	83,000
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 2
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	426,000	413,000
Consumer loans	49,000	55,000
Trading account securities	3,000	3,000
Available-for-sale securities	11,372,000	11,673,000
MSRs	0	0
Gross amounts of recognized assets	350,000	316,000
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	433,000	326,000
Short-term borrowings	0
Fair Value, Measurements, Recurring | Level 2 | U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 2 | Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	7,531,000	6,484,000
Fair Value, Measurements, Recurring | Level 2 | Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	187,000	70,000
Fair Value, Measurements, Recurring | Level 2 | Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	2,000
Available-for-sale securities	604,000	711,000
Fair Value, Measurements, Recurring | Level 2 | Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	427,000	443,000
Fair Value, Measurements, Recurring | Level 2 | Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	102,000	109,000
Fair Value, Measurements, Recurring | Level 2 | Other Debt Obligations [Member]
Assets measured at fair value on a recurring basis
Trading account securities	1,000	3,000
Available-for-sale securities	6,000	2,000
Fair Value, Measurements, Recurring | Level 2 | Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	724,000	1,367,000
Fair Value, Measurements, Recurring | Level 2 | Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,791,000	2,487,000
Fair Value, Measurements, Recurring | Level 3
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	0	0
Consumer loans	37,000	38,000
Trading account securities	0	0
Available-for-sale securities	3,230,000	3,191,000
MSRs	12,000	11,000
Gross amounts of recognized assets	6,000	6,000
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	6,000	5,000
Short-term borrowings	0
Fair Value, Measurements, Recurring | Level 3 | U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	0
Available-for-sale securities	3,230,000	3,167,000
Fair Value, Measurements, Recurring | Level 3 | Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	24,000
Fair Value, Measurements, Recurring | Level 3 | Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Other Debt Obligations [Member]
Assets measured at fair value on a recurring basis
Trading account securities	0	0
Available-for-sale securities	$ 0	$ 0

FAIR VALUES OF ASSETS AND LIA87

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	$ 14,607,000		$ 14,869,000
MSRs
Assets Level 3 Roll Forward:
Opening balance	11,000	$ 14,000
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	1,000	(1,000)
Included in OCI	0	0
Purchases/originations	0	0
Sales	0	0
Repayments	0	0
Settlements	0	0
Closing balance	12,000	13,000
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	1,000	0
Derivative [Member]
Assets Level 3 Roll Forward:
Opening balance	(1,000)	(2,000)
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	5,000	0
Total gains/losses for the period:
Included in earnings	6,000	5,000
Included in OCI	0	0
Purchases/originations	0	0
Sales	0	0
Repayments	0	0
Settlements	0	0
Closing balance	0	3,000
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	5,000
Municipal securities
Assets Level 3 Roll Forward:
Opening balance	3,167,000	2,798,000
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	(1,000)	(1,000)
Included in OCI	(28,000)	20,000
Purchases/originations	193,000	133,000
Sales	0
Repayments	0	0
Settlements	(101,000)	(82,000)
Closing balance	3,230,000	2,868,000
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	20,000
Asset-backed securities
Assets Level 3 Roll Forward:
Opening balance	24,000	76,000
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	(2,000)	0
Included in OCI	11,000	3,000
Purchases/originations	0	0
Sales	(33,000)	(19,000)
Repayments	0	0
Settlements	0	(1,000)
Closing balance	0	59,000
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	1,000
Automobile
Assets Level 3 Roll Forward:
Opening balance	38,000	48,000
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	0	0
Included in OCI	0	0
Purchases/originations	0	0
Sales	0	0
Repayments	(1,000)	(4,000)
Settlements	0	0
Closing balance	37,000	44,000
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	$ 0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	1,791,000		2,487,000
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	724,000		1,367,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	14,607,000		14,869,000
Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	1,791,000		2,487,000
Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	724,000		1,367,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	11,372,000		11,673,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	1,791,000		2,487,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	$ 724,000		$ 1,367,000

FAIR VALUES OF ASSETS AND LIA88

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	$ (1)	$ 1
Securities gains (losses)	0	0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	1	1
Derivative Financial Instruments, Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	(6)	(5)
Securities gains (losses)	0	0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	(6)	(5)
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	0	0
Securities gains (losses)	0	(1)
Other expense	(1)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	1	1
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	0	0
Securities gains (losses)	(2)	0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	2	0
Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	0	0
Securities gains (losses)	0	0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	$ 0	$ 0

FAIR VALUES OF ASSETS AND LIA89

FAIR VALUES OF ASSETS AND LIABILITIES - Fair Value Option (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 426	$ 413
Loans Receivable, Fair Value Disclosure	86	93
Fair Value, Measurements, Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	426	413
Fair Value, Measurements, Recurring | Mortgages Held For Sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	426	413
Loans Held For Sale Unpaid Principal	416	400
Difference	(10)	(13)
Fair Value, Measurements, Recurring | Mortgages Held To Maturity
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Receivable, Fair Value Disclosure	86	93
Loans Held To Maturity Unpaid Principal	94	102
Difference	(8)	(9)
Fair Value, Measurements, Recurring | 90 or more days | Mortgages Held For Sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	1	1
Loans Held For Sale Unpaid Principal	1	1
Difference	0	0
Fair Value, Measurements, Recurring | 90 or more days | Mortgages Held To Maturity
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Receivable, Fair Value Disclosure	8	10
Loans Held To Maturity Unpaid Principal	9	11
Difference	$ (1)	$ (1)

FAIR VALUES OF ASSETS AND LIA90

FAIR VALUES OF ASSETS AND LIABILITIES - Fair Value Option-Changs in Fair Value (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Measurements, Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) from fair value changes	$ 2	$ 9
Consumer loans
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) from fair value changes	$ 0	$ 0

FAIR VALUES OF ASSETS AND LIA91

FAIR VALUES OF ASSETS AND LIABILITIES - Non-Recurring Basis (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		$ 85	$ 86
Loans held for sale	[1]	506	488
Available-for-sale securities		14,607	14,869
Long-term debt		8,618	9,206
Held-to-maturity securities		8,789	9,091
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		70,442	69,426
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		85	86
Loans held for sale		510	491
Available-for-sale securities		14,607	14,869
Long-term debt		8,771	9,402
Held-to-maturity securities		8,550	8,971
Other Securities		602	600
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		69,820	69,146
Level 1 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		82
Loans held for sale		0	0
Available-for-sale securities		5	5
Long-term debt		0	0
Held-to-maturity securities		0	0
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		0	0
Level 2 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		3
Loans held for sale		426	413
Available-for-sale securities		11,372	11,673
Long-term debt		8,299	8,944
Held-to-maturity securities		8,550	8,971
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		0	0
Level 3 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		0	0
Loans held for sale		84	78
Available-for-sale securities		3,230	3,191
Long-term debt		472	458
Held-to-maturity securities		0	0
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		69,820	69,146
Nonrecurring Basis
Assets measured at fair value on a nonrecurring basis
Impaired loans			(36)
Other real estate owned			(33)
Nonrecurring Basis | Fair Value
Assets measured at fair value on a nonrecurring basis
Impaired loans		(58)
Other real estate owned		(30)
Nonrecurring Basis | Total Gains/(Losses)
Assets measured at fair value on a nonrecurring basis
Impaired loans		0
Other real estate owned		0
Nonrecurring Basis | Level 1 | Fair Value
Assets measured at fair value on a nonrecurring basis
Impaired loans		0
Other real estate owned		0
Nonrecurring Basis | Level 2 | Fair Value
Assets measured at fair value on a nonrecurring basis
Impaired loans		0
Other real estate owned		0
Nonrecurring Basis | Level 3
Assets measured at fair value on a nonrecurring basis
MSRs			$ 190
Nonrecurring Basis | Level 3 | Fair Value
Assets measured at fair value on a nonrecurring basis
Impaired loans		(58)
Other real estate owned		$ (30)
[1]	Amounts represent loans for which Huntington has elected the fair value option.

FAIR VALUES OF ASSETS AND LIA92

FAIR VALUES OF ASSETS AND LIABILITIES - Significant Unobservable Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Gross amounts of recognized assets	$ 356,000	$ 322,000
Derivative Liability, Fair Value, Gross Liability	439,000	331,000
Available-for-sale securities	14,607,000	14,869,000
Consumer loans	86,000	93,000
Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
MSRs	12,000	11,000
Available-for-sale securities	14,607,000	14,869,000
Fair Value, Measurements, Recurring | Level 3
Fair Value Disclosures [Abstract]
MSRs	12,000	11,000
Gross amounts of recognized assets	6,000	6,000
Derivative Liability, Fair Value, Gross Liability	6,000	5,000
Available-for-sale securities	3,230,000	3,191,000
Consumer loans	37,000	38,000
Fair Value, Measurements, Nonrecurring
Fair Value Disclosures [Abstract]
Impaired loans Fair Value Disclosure		36,000
Accrued income and other assets Fair Value Disclosure		33,000
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value Disclosures [Abstract]
MSRs		190,000
Asset-backed securities
Fair Value Disclosures [Abstract]
Available-for-sale securities	427,000	467,000
Asset-backed securities | Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
Available-for-sale securities	427,000	467,000
Asset-backed securities | Fair Value, Measurements, Recurring | Level 3
Fair Value Disclosures [Abstract]
Available-for-sale securities	0	24,000
Municipal securities
Fair Value Disclosures [Abstract]
Available-for-sale securities	3,834,000	3,878,000
Municipal securities | Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
Available-for-sale securities	3,834,000	3,878,000
Municipal securities | Fair Value, Measurements, Recurring | Level 3
Fair Value Disclosures [Abstract]
Available-for-sale securities	$ 3,230,000	$ 3,167,000
Cost Approach Valuation Technique | Maximum | Fair Value, Measurements, Recurring | MSRs | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	31.00%	33.00%
Spread over forward interest rate swap rates	0.11	0.10
Cost Approach Valuation Technique | Maximum | Fair Value, Measurements, Recurring | Private label CMO | Level 3
Fair Value Disclosures [Abstract]
Discount rate	9.00%	10.00%
Cumulative default	64.00%	64.00%
Loss given default	90.00%	90.00%
Cost Approach Valuation Technique | Maximum | Fair Value, Measurements, Recurring | Asset-backed securities | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	72.00%
Discount rate	0.00%	7.00%
Cumulative default	0.00%	53.00%
Loss given default	0.00%	100.00%
Cure given deferral	0.00%	50.00%
Cost Approach Valuation Technique | Maximum | Fair Value, Measurements, Recurring | Loans held for investment | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	22.00%	22.00%
Discount rate	18.00%	18.00%
Cost Approach Valuation Technique | Maximum | Fair Value, Measurements, Nonrecurring | MSRs | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	21.00%
Spread over forward interest rate swap rates	0	0.2
Cost Approach Valuation Technique | Minimum | Fair Value, Measurements, Recurring | MSRs | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	6.00%	8.00%
Spread over forward interest rate swap rates	0.05	0.08
Cost Approach Valuation Technique | Minimum | Fair Value, Measurements, Recurring | Private label CMO | Level 3
Fair Value Disclosures [Abstract]
Discount rate	0.00%	0.00%
Cumulative default	0.00%	0.00%
Loss given default	5.00%	5.00%
Cost Approach Valuation Technique | Minimum | Fair Value, Measurements, Recurring | Asset-backed securities | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	0.00%
Discount rate	0.00%	7.00%
Cumulative default	0.00%	3.00%
Loss given default	0.00%	90.00%
Cure given deferral	0.00%	50.00%
Cost Approach Valuation Technique | Minimum | Fair Value, Measurements, Recurring | Loans held for investment | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	2.00%	2.00%
Discount rate	7.00%	7.00%
Cost Approach Valuation Technique | Minimum | Fair Value, Measurements, Nonrecurring | MSRs | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	6.00%
Spread over forward interest rate swap rates	0	0.02
Cost Approach Valuation Technique | Weighted Average | Fair Value, Measurements, Recurring | MSRs | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	9.00%	12.00%
Spread over forward interest rate swap rates	0.080	0.080
Cost Approach Valuation Technique | Weighted Average | Fair Value, Measurements, Recurring | Private label CMO | Level 3
Fair Value Disclosures [Abstract]
Discount rate	3.00%	4.00%
Cumulative default	3.00%	3.00%
Loss given default	25.00%	24.00%
Cost Approach Valuation Technique | Weighted Average | Fair Value, Measurements, Recurring | Asset-backed securities | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	7.00%
Discount rate	0.00%	7.00%
Cumulative default	0.00%	7.00%
Loss given default	0.00%	98.00%
Cure given deferral	0.00%	50.00%
Cost Approach Valuation Technique | Weighted Average | Fair Value, Measurements, Recurring | Loans held for investment | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	8.00%	9.00%
Discount rate	8.00%	8.00%
Cost Approach Valuation Technique | Weighted Average | Fair Value, Measurements, Nonrecurring | MSRs | Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	8.00%
Spread over forward interest rate swap rates	0	0.100
Market Approach Valuation Technique | Maximum | Fair Value, Measurements, Recurring | Derivative [Member] | Level 3
Fair Value Disclosures [Abstract]
Net market price	20.00%	20.00%
Estimated Pull through %	100.00%	100.00%
Market Approach Valuation Technique | Minimum | Fair Value, Measurements, Recurring | Derivative [Member] | Level 3
Fair Value Disclosures [Abstract]
Net market price	(5.00%)	(5.00%)
Estimated Pull through %	0.00%	3.00%
Market Approach Valuation Technique | Weighted Average | Fair Value, Measurements, Recurring | Derivative [Member] | Level 3
Fair Value Disclosures [Abstract]
Net market price	2.00%	2.00%
Estimated Pull through %	85.00%	75.00%
Derivative Financial Instruments, Liabilities [Member] | Market Approach Valuation Technique | Minimum | Level 3
Fair Value Disclosures [Abstract]
Fair Value Inputs, Estimated conversion factor	165.00%	165.00%
Fair Value Inputs, Estimated growth rate of Visa Class A shares	7.00%	7.00%
Discount rate	3.00%	3.00%
Fair Value Inputs, Timing of the resolution of the litigation	Mar. 31, 2018	Dec. 31, 2017
Derivative Financial Instruments, Liabilities [Member] | Market Approach Valuation Technique | Weighted Average | Level 3
Fair Value Disclosures [Abstract]
Fair Value Inputs, Timing of the resolution of the litigation	Jun. 30, 2020	Jun. 30, 2020

FAIR VALUES OF ASSETS AND LIA93

FAIR VALUES OF ASSETS AND LIABILITIES - Balance Sheet Location (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Financial Assets:
Trading account securities		$ 85,000	$ 86,000
Available-for-sale securities		14,607,000	14,869,000
Held-to-maturity securities, Total		8,789,000	9,091,000
Loans held for sale	[1]	506,000	488,000
Net loans and direct financing leases		70,442,000	69,426,000
Derivatives		87,000	132,000
Financial Liabilities:
Deposits		79,471,000	77,041,000
Short-term borrowings		2,854,000	5,056,000
Long-term borrowings		8,618,000	9,206,000
Derivatives		157,000	86,000
Reported Value Measurement [Member]
Financial Assets:
Cash and short term assets		1,115,000	1,567,000
Trading account securities		85,000	86,000
Available-for-sale securities		14,607,000	14,869,000
Held-to-maturity securities, Total		8,789,000	9,091,000
Loans held for sale		506,000	488,000
Other Securities		602,000	600,000
Net loans and direct financing leases		70,442,000	69,426,000
Derivatives		87,000	132,000
Financial Liabilities:
Deposits		79,471,000	77,041,000
Short-term borrowings		2,854,000	5,056,000
Long-term borrowings		8,618,000	9,206,000
Derivatives		157,000	86,000
Estimate of Fair Value Measurement [Member]
Financial Assets:
Cash and short term assets		1,115,000	1,567,000
Trading account securities		85,000	86,000
Available-for-sale securities		14,607,000	14,869,000
Held-to-maturity securities, Total		8,550,000	8,971,000
Loans held for sale		510,000	491,000
Other Securities		602,000	600,000
Other securities		21,000	19,000
Net loans and direct financing leases		69,820,000	69,146,000
Derivatives		87,000	132,000
Financial Liabilities:
Deposits		79,425,000	77,010,000
Short-term borrowings		2,854,000	5,056,000
Long-term borrowings		8,771,000	9,402,000
Derivatives		157,000	86,000
Estimate of Fair Value Measurement [Member] | Level 1
Financial Assets:
Trading account securities		82,000
Available-for-sale securities		5,000	5,000
Held-to-maturity securities, Total		0	0
Loans held for sale		0	0
Other securities		21,000	19,000
Net loans and direct financing leases		0	0
Financial Liabilities:
Deposits		0	0
Short-term borrowings		1,000	0
Long-term borrowings		0	0
Estimate of Fair Value Measurement [Member] | Level 2
Financial Assets:
Trading account securities		3,000
Available-for-sale securities		11,372,000	11,673,000
Held-to-maturity securities, Total		8,550,000	8,971,000
Loans held for sale		426,000	413,000
Other securities		0	0
Net loans and direct financing leases		0	0
Financial Liabilities:
Deposits		74,573,000	73,975,000
Short-term borrowings		0	0
Long-term borrowings		8,299,000	8,944,000
Estimate of Fair Value Measurement [Member] | Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		3,230,000	3,191,000
Held-to-maturity securities, Total		0	0
Loans held for sale		84,000	78,000
Other securities		0	0
Net loans and direct financing leases		69,820,000	69,146,000
Financial Liabilities:
Deposits		4,852,000	3,035,000
Short-term borrowings		2,853,000	5,056,000
Long-term borrowings		472,000	458,000
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account securities		85,000	86,000
Available-for-sale securities		14,607,000	14,869,000
Derivatives		87,000	132,000
Financial Liabilities:
Derivatives		157,000	86,000
Fair Value, Measurements, Recurring [Member] | Level 1
Financial Assets:
Trading account securities		82,000	83,000
Available-for-sale securities		5,000	5,000
Fair Value, Measurements, Recurring [Member] | Level 2
Financial Assets:
Trading account securities		3,000	3,000
Available-for-sale securities		11,372,000	11,673,000
Fair Value, Measurements, Recurring [Member] | Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		3,230,000	3,191,000
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account securities		83,000	86,000
Available-for-sale securities		6,000	2,000
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Level 1
Financial Assets:
Trading account securities		82,000	83,000
Available-for-sale securities		0	0
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Level 2
Financial Assets:
Trading account securities		1,000	3,000
Available-for-sale securities		6,000	2,000
Other Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member] | Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		0	0
Amortized Cost [Member] | Reported Value Measurement [Member]
Financial Assets:
Cash and short term assets		1,115,000	1,567,000
Held-to-maturity securities, Total		8,789,000	9,091,000
Other Securities		581,000	581,000
Net loans and direct financing leases		70,356,000	69,333,000
Financial Liabilities:
Deposits		79,471,000	77,041,000
Short-term borrowings		2,854,000	5,056,000
Long-term borrowings		8,618,000	9,206,000
Fair Value Fair Value Option [Member] | Reported Value Measurement [Member]
Financial Assets:
Trading account securities		85,000	86,000
Available-for-sale securities		14,607,000	14,869,000
Loans held for sale		426,000	413,000
Other Securities		21,000	19,000
Net loans and direct financing leases		86,000	93,000
Derivatives		87,000	132,000
Financial Liabilities:
Derivatives		157,000	86,000
LowerOfCostOrMarket [Member] | Reported Value Measurement [Member]
Financial Assets:
Loans held for sale		$ 80,000	$ 75,000
[1]	Amounts represent loans for which Huntington has elected the fair value option.

DERIVATIVE FINANCIAL INSTRUME94

DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)group	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Derivative [Line Items]
Increase (decrease) to net interest income due to derivative adjustment	$ 1	$ 10
Derivative Liability	157		$ 86
Purchase of interest rate caps and derivative financial instruments, notional value	7,852		8,375
Total notional amount corresponds to trading assets, fair value (less than)	1
Credit risks from interest rate swaps used for trading purposes	$ 53		119
Additional information about interest rate swaps used in asset and liability management activities [Table Text Block]	The following table presents additional information about the interest rate swaps used in Huntington’s asset and liability management activities at March 31, 2018 and December 31, 2017 . March 31, 2018 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Asset conversion swaps Receive fixed—generic $ 12 2.0 $ — 2.20 % 1.78 % Liability conversion swaps Receive fixed—generic 7,840 2.4 (176 ) 1.57 1.88 Total swap portfolio at March 31, 2018 $ 7,852 2.4 $ (176 ) December 31, 2017 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Liability conversion swaps Receive fixed—generic 8,375 2.5 (99 ) 1.56 1.44 Total swap portfolio at December 31, 2017 $ 8,375 2.5 $ (99 )
Number of primary groups | group	2
Aggregate credit risk, net of collateral	$ 27		30
Investment securities and cash collateral pledged by Huntington	95
Investment securities and cash collateral pledged to Huntington	$ 74
Swap
Derivative [Line Items]
Additional information about interest rate swaps used in asset and liability management activities [Table Text Block]	5
Derivative used in trading activity
Derivative [Line Items]
Net derivative asset (liability)	$ 90		88
Derivative financial instruments used by Huntington on behalf of customers including offsetting derivatives, notional value	23,000		22,000
Derivative used in Mortgage Banking Activities
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	125		188
Gains (losses) related to derivative instruments Included in total MSR	(8)	$ (1)
Fair Value Hedging
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	7,840		8,375
Cash Flow Hedging
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	$ 12		$ 0

DERIVATIVE FINANCIAL INSTRUME95

DERIVATIVE FINANCIAL INSTRUMENTS - Hedging Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 7,852	$ 8,375
Asset derivatives included in accrued income and other assets
Total contracts	356	322
Liability derivatives included in accrued expenses and other liabilities
Total contracts	439	331
Accrued income and other assets
Asset derivatives included in accrued income and other assets
Interest rate contracts designated as hedging instruments	15	22
Interest rate contracts not designated as hedging instruments	228	187
Foreign exchange contracts not designated as hedging instruments	20	18
Commodities contracts not designated as hedging instruments	89	92
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	4	3
Total contracts	356	322
Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Interest rate contracts designated as hedging instruments	191	121
Interest rate contracts not designated as hedging instruments	138	100
Foreign exchange contracts not designated as hedging instruments	22	18
Commodities contracts not designated as hedging instruments	83	87
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	5	5
Total contracts	$ 439	$ 331

DERIVATIVE FINANCIAL INSTRUME96

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	2 years 5 months 1 day
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 7,852	$ 8,375
Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	7,840	8,375
Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	12	0
Subordinated notes
Notional Disclosures [Abstract]
Derivative, Notional Amount	950	950
Subordinated notes | Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	950	950
Subordinated notes | Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
Securities Investment [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	12
Securities Investment [Member] | Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	0
Securities Investment [Member] | Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	12
Other long-term debt
Notional Disclosures [Abstract]
Derivative, Notional Amount	6,890	7,425
Other long-term debt | Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	6,890	7,425
Other long-term debt | Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 0	$ 0
Asset conversion swaps Receive Fixed Generic [Member]
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	1 year 11 months 15 days	0 years
Liability conversion swaps Receive Fixed Generic [Member]
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years		2 years 6 months

DERIVATIVE FINANCIAL INSTRUME97

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Managemen Add Info (Details Add Info) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative, Notional Amount	$ 7,852,000	$ 8,375,000
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 7,852,000	8,375,000
Average Maturity (years)	2 years 5 months 1 day
Fair Value	$ (176,000)	$ (99,000)
Weighted-Average Rate Receive
Weighted-Average Rate Pay
Asset conversion swaps - Receive Fixed - Generic
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 12,000
Average Maturity (years)	1 year 11 months 15 days	0 years
Fair Value	$ (32)
Weighted-Average Rate Receive	2.20%
Weighted-Average Rate Pay	1.78%
Liability conversion swaps - Receive Fixed - Generic
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 7,840,000	$ 8,375,000
Average Maturity (years)		2 years 6 months
Fair Value	$ (175,630)	$ (99,000)
Weighted-Average Rate Receive	1.57%	1.56%
Weighted-Average Rate Pay	1.88%	1.44%

DERIVATIVE FINANCIAL INSTRUME98

DERIVATIVE FINANCIAL INSTRUMENTS - Gain (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) [Table Text Block]	The following table presents the amount of gain or loss recognized in income for derivatives not designated as hedging instruments under ASC Subtopic 815-10 in the Unaudited Condensed Consolidated Income Statement for the three months ended March 31, 2018 . Location of Gain or (Loss) Recognized in Income on Derivative Amount of Gain or (Loss) Recognized in Income on Derivative (dollar amounts in millions) Three Months Ended March 31, 2018 Interest rate contracts: Customer Capital markets fees $ 7 MSR Mortgage banking income (8 ) Foreign exchange contracts Capital markets fees 6 Commodities contracts Capital markets fees 2 Equity contracts Other noninterest expense (1 ) Total $ 6 The following table presents the gains and (losses) recognized in OCI and the location in the Unaudited Condensed Consolidated Statements of Income of gains and (losses) reclassified from OCI into earnings for derivatives designated as effective cash flow hedges for the three-month periods ended March 31, 2018 and 2017 . Derivatives in cash flow hedging relationships Amount of gain or (loss) recognized in OCI on derivatives (effective portion) (after-tax) Location of gain or (loss) reclassified from accumulated OCI into earnings (effective portion) Amount of (gain) or loss reclassified from accumulated OCI into earnings (effective portion) Three Months Ended March 31, Three Months Ended March 31, (dollar amounts in millions) 2018 2017 2018 2017 Interest rate contracts Loans $ — $ (1 ) Interest and fee income - loans and leases $ — $ 1 Investment securities — — Noninterest income - other income — — Total $ — $ (1 ) $ — $ 1
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 6
Gain (Loss) on Commodity Contract Derivative Instruments Not Designated as Hedging Instruments	2
Gain (Loss) on Equity Contract Derivative Instruments Not Designated as Hedging Instruments	(1)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	6
Cash Flow Hedging
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Amount of gain or (loss) recognized in OCI on derivatives (effective portion)	0	$ (1)
Amount of gain or (loss) reclassified from accumulated OCI into earnings (effective portion)	0	1
Subordinated notes | Interest expense subordinated notes and other long term debt
Increase or (decrease) to interest expense for derivatives designated as fair value hedges
Increase or (decrease) to interest expense for derivatives designated as fair value hedges	(17)	(5)
Hedged Subordinated notes | Interest expense subordinated notes and other long term debt
Increase or (decrease) to interest expense for derivatives designated as fair value hedges
Increase or (decrease) to interest expense for derivatives designated as fair value hedges	18	5
Other long-term debt | Interest expense subordinated notes and other long term debt
Increase or (decrease) to interest expense for derivatives designated as fair value hedges
Increase or (decrease) to interest expense for derivatives designated as fair value hedges	(51)	(10)
Hedged Other long term debt | Interest expense subordinated notes and other long term debt
Increase or (decrease) to interest expense for derivatives designated as fair value hedges
Increase or (decrease) to interest expense for derivatives designated as fair value hedges	53	9
Loan | Interest and fee income loans and leases | Cash Flow Hedging
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Amount of gain or (loss) recognized in OCI on derivatives (effective portion)	0	(1)
Amount of gain or (loss) reclassified from accumulated OCI into earnings (effective portion)	0	1
Securities Investment [Member] | Interest and fee income investment securities | Cash Flow Hedging
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Amount of gain or (loss) recognized in OCI on derivatives (effective portion)	0	0
Amount of gain or (loss) reclassified from accumulated OCI into earnings (effective portion)	0	$ 0
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	7
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ (8)
Commodities contracts [Domain]
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Description of Location of Gain (Loss) on Commodity Contract Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Capital markets fees
Foreign currency contract [Domain]
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Description of Location of Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Capital markets fees
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Capital markets fees
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Description of Location of Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Mortgage banking income
Equity contracts [Domain]
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Description of Location of Gain (Loss) on Equity Contract Derivative Instruments Not Designated as Hedging Instruments in Financial Statements	Other noninterest expense

DERIVATIVE FINANCIAL INSTRUME99

DERIVATIVE FINANCIAL INSTRUMENTS - Fair Value Hedges (Details) $ in Millions	Mar. 31, 2018USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge Liabilities	$ 7,709
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	$ (186)

DERIVATIVE FINANCIAL INSTRUM100

DERIVATIVE FINANCIAL INSTRUMENTS - Mortgage Banking Activities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Derivative assets:
Total derivative assets	$ 356		$ 322
Derivative liabilities:
Total derivative liabilities	(439)		(331)
Interest rate lock agreements
Derivative assets:
Total derivative assets	6		6
Derivative liabilities:
Total derivative liabilities	1		0
Forward trades and options
Derivative assets:
Total derivative assets	2		1
Derivative liabilities:
Total derivative liabilities	2		0
Derivative used in Mortgage Banking Activities
Derivatives, Fair Value [Line Items]
Gains losses related to derivative instruments Included in Mortgage securities	(8)	$ (1)
Derivative assets:
Total derivative assets	8		7
Derivative liabilities:
Total derivative liabilities	$ 3		$ 0

DERIVATIVE FINANCIAL INSTRUM101

DERIVATIVE FINANCIAL INSTRUMENTS - Offsetting Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets	$ 356	$ 322
Gross amounts offset in the condensed consolidated balance sheets	269	190
Net amounts of assets presented in the condensed consolidated balance sheets	87	132
Gross amounts not offset in the condensed consolidated balance sheets, Financial instruments	(2)	(11)
Gross amounts not offset in the condensed consolidated balance sheets, cash collateral received	(11)	(18)
Net amount	$ 74	$ 103

DERIVATIVE FINANCIAL INSTRUM102

DERIVATIVE FINANCIAL INSTRUMENTS - Offsetting Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	$ 439	$ 331
Gross amounts offset in the condensed consolidated balance sheets	(282)	(245)
Derivative liabilities	157	86
Gross amounts not offset in the condensed consolidated balance sheets, Financial instruments	0	0
Gross amounts not offset in the condensed consolidated balance sheets, Cash collateral received	(21)	(21)
Net amount	$ 136	$ 65

VIEs - Narrative (Details)

VIEs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Sep. 30, 2015
Trust 2016 Unconsolidated [Member]
Variable Interest Entity [Line Items]
Total of automobile loans transferred in securitization transactions	$ 1,500
2015-1 Automobile Trust
Variable Interest Entity [Line Items]
Total of automobile loans transferred in securitization transactions		$ 750

VIEs - Unconsolidated VIEs (Det

VIEs - Unconsolidated VIEs (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Trust 2016 Unconsolidated [Member]
Variable Interest Entity [Line Items]
Total Assets	$ 6	$ 7
Total Liabilities	1	0
Maximum Exposure to Loss	6	7
2015-1 Automobile Trust
Variable Interest Entity [Line Items]
Total Assets	1	1
Total Liabilities	0	0
Maximum Exposure to Loss	1	1
Trust Preferred Securities
Variable Interest Entity [Line Items]
Total Assets	14	14
Total Liabilities	252	252
Maximum Exposure to Loss	0	0
Affordable Housing Tax Credit Partnerships
Variable Interest Entity [Line Items]
Total Assets	634	636
Total Liabilities	320	335
Maximum Exposure to Loss	634	636
Other Investments
Variable Interest Entity [Line Items]
Total Assets	122	117
Total Liabilities	57	53
Maximum Exposure to Loss	122	117
Total
Variable Interest Entity [Line Items]
Total Assets	777	775
Total Liabilities	630	640
Maximum Exposure to Loss	$ 763	$ 761

VIEs - Trust preferred Securiti

VIEs - Trust preferred Securities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Summary of Outstanding Trust Preferred Securities
Principal amount of subordinated note/ debenture issued to trust	$ 252
Investment in unconsolidated subsidiary	$ 14
Summary of Outstanding Trust Preferred Securities (Textuals) [Abstract]
Maximum year to defer payment of interest on Debenture	5 years
Huntington Capital I
Summary of Outstanding Trust Preferred Securities
Interest rate on Trust Preferred Securities	3.01%
Principal amount of subordinated note/ debenture issued to trust	$ 70
Investment in unconsolidated subsidiary	$ 6
Huntington Capital I | London Interbank Offered Rate (LIBOR) [Member]
Summary of Outstanding Trust Preferred Securities (Textuals) [Abstract]
Rate spread over three month LIBOR	0.70%
Huntington Capital II
Summary of Outstanding Trust Preferred Securities
Interest rate on Trust Preferred Securities	2.94%
Principal amount of subordinated note/ debenture issued to trust	$ 32
Investment in unconsolidated subsidiary	$ 3
Huntington Capital II | London Interbank Offered Rate (LIBOR) [Member]
Summary of Outstanding Trust Preferred Securities (Textuals) [Abstract]
Rate spread over three month LIBOR	0.625%
Sky Financial Capital Trust III
Summary of Outstanding Trust Preferred Securities
Interest rate on Trust Preferred Securities	3.71%
Principal amount of subordinated note/ debenture issued to trust	$ 72
Investment in unconsolidated subsidiary	$ 2
Sky Financial Capital Trust III | London Interbank Offered Rate (LIBOR) [Member]
Summary of Outstanding Trust Preferred Securities (Textuals) [Abstract]
Rate spread over three month LIBOR	1.40%
Sky Financial Capital Trust IV
Summary of Outstanding Trust Preferred Securities
Interest rate on Trust Preferred Securities	3.71%
Principal amount of subordinated note/ debenture issued to trust	$ 74
Investment in unconsolidated subsidiary	$ 2
Camco Financial Trust
Summary of Outstanding Trust Preferred Securities
Interest rate on Trust Preferred Securities	3.64%
Principal amount of subordinated note/ debenture issued to trust	$ 4
Investment in unconsolidated subsidiary	$ 1
Camco Financial Trust | London Interbank Offered Rate (LIBOR) [Member]
Summary of Outstanding Trust Preferred Securities (Textuals) [Abstract]
Rate spread over three month LIBOR	1.33%

VIEs - Low Income Housing Tax C

VIEs - Low Income Housing Tax Credit Partnership (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Low Income Housing Tax Credit Partnerships
Variable Interest Entity [Line Items]
Affordable housing tax credit investments	$ 1,013		$ 996
Less: amortization	(379)		(360)
Net affordable housing tax credit investments	634		636
Unfunded commitments	320		$ 335
Tax credits and other tax benefits recognized	23	$ 23
Proportional Amortization Method
Variable Interest Entity [Line Items]
Tax credit amortization expense included in provision for income taxes	$ 19	$ 17

COMMITMENTS AND CONTINGENT L107

COMMITMENTS AND CONTINGENT LIABILITIES - Commitments to Extend Credit (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Commercial
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	$ 16,265	$ 16,219
Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	14,353	13,384
Commercial Real Estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	1,323	1,366
Standby Letters of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	583	510
Commercial | Letter of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	$ 17	$ 21

COMMITMENTS AND CONTINGENT L108

COMMITMENTS AND CONTINGENT LIABILITIES - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Maturity period of majority of standby letters of credit	P2Y
Maturity period of Commercial letters of credit	P90D
Maturity period of forward contracts relating mortgage banking business	1 year
Standby Letters of Credit
Loss Contingencies [Line Items]
Carrying amount of deferred revenue associated with guarantees	$ 11,000,000	$ 10,000,000
Outstanding standby letters of credit	583,000,000	510,000,000
Commitments to Sell Loans
Loss Contingencies [Line Items]
Commitments to sell residential real estate loans	800,000,000	$ 696,000,000
Maximum
Loss Contingencies [Line Items]
Aggregate range of reasonably possible losses current legal proceedings	30,000,000
Minimum
Loss Contingencies [Line Items]
Aggregate range of reasonably possible losses current legal proceedings	$ 0

SEGMENT REPORTING (Details)

SEGMENT REPORTING (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)reporting_unitsegments	Mar. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | segments	4
Maximum business banking customer's revenue	$ 20
Net interest income	770	$ 730
Provision (reduction in allowance) for credit losses	(66)	(68)
Noninterest income	314	312
Noninterest expense	633	707
Provision (benefit) for income taxes	59	59
Net income	326	208
Assets	104,246		$ 104,185
Deposits	79,471		77,041
Operating Segments | Consumer & Business Banking
Segment Reporting Information [Line Items]
Net interest income	395	375
Provision (reduction in allowance) for credit losses	(31)	(33)
Noninterest income	174	171
Noninterest expense	412	413
Provision (benefit) for income taxes	26	35
Net income	100	65
Assets	26,346		26,220
Deposits	$ 47,124		45,643
Operating Segments | Commercial Banking
Segment Reporting Information [Line Items]
Number of reporting units | reporting_unit	6
Net interest income	$ 220	228
Provision (reduction in allowance) for credit losses	(21)	(21)
Noninterest income	69	64
Noninterest expense	120	117
Provision (benefit) for income taxes	31	54
Net income	117	100
Assets	32,744		32,118
Deposits	21,838		21,235
Operating Segments | Vehicle Finance [Member]
Segment Reporting Information [Line Items]
Net interest income	99	104
Provision (reduction in allowance) for credit losses	(14)	(11)
Noninterest income	3	5
Noninterest expense	35	36
Provision (benefit) for income taxes	11	22
Net income	42	40
Assets	18,138		17,865
Deposits	345		358
Operating Segments | RBPCG
Segment Reporting Information [Line Items]
Net interest income	45	45
Provision (reduction in allowance) for credit losses	0	(3)
Noninterest income	51	48
Noninterest expense	58	63
Provision (benefit) for income taxes	8	10
Net income	30	17
Assets	5,888		5,821
Deposits	6,053		6,057
Treasury / Other
Segment Reporting Information [Line Items]
Net interest income	11	(22)
Provision (reduction in allowance) for credit losses	0	0
Noninterest income	17	24
Noninterest expense	8	78
Provision (benefit) for income taxes	(17)	(62)
Net income	37	$ (14)
Assets	21,130		22,161
Deposits	$ 4,111		$ 3,748