Huntington Bancshares (HBAN) 10-Q30 Jul 182018 Q2 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information	6 Months Ended
Document and Entity Information	Jun. 30, 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	Jun. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
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)	1,104,226,603

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Assets
Cash and due from banks		$ 1,382,000	$ 1,520,000
Interest-bearing deposits in banks		41,000	47,000
Trading account securities		85,000	86,000
Available-for-sale securities		14,070,000	14,869,000
Held-to-maturity securities		8,682,000	9,091,000
Other Securities, Fair Value		597,000	600,000
Loans held for sale (includes $643 and $413 respectively, measured at fair value)(1)	[1]	709,000	488,000
Loans and leases (includes $84 and $93 respectively, measured at fair value)(1)	[1]	72,406,000	70,117,000
Allowance for loan and lease losses		(741,000)	(691,000)
Net loans and leases		71,665,000	69,426,000
Bank owned life insurance		2,488,000	2,466,000
Premises and equipment		840,000	864,000
Goodwill		1,993,000	1,993,000
Other intangible assets		319,000	346,000
Servicing rights		248,000	238,000
Accrued income and other assets		2,239,000	2,151,000
Total assets		105,358,000	104,185,000
Liabilities
Deposits		79,587,000	77,041,000
Short-term borrowings		2,442,000	5,056,000
Long-term debt		9,726,000	9,206,000
Accrued expenses and other liabilities		2,131,000	2,068,000
Total liabilities		93,886,000	93,371,000
Shareholders’ equity
Preferred Stock, Value, Issued		1,203,000	1,071,000
Common stock		11,000	11,000
Capital surplus		10,038,000	9,707,000
Less treasury shares, at cost		(40,000)	(35,000)
Accumulated other comprehensive loss		(730,000)	(528,000)
Retained earnings		990,000	588,000
Total shareholders’ equity		11,472,000	10,814,000
Total liabilities and shareholders’ equity		$ 105,358,000	$ 104,185,000
Common shares authorized (par value of $0.01) (in shares)		1,500,000,000	1,500,000,000
Common shares issued (in shares)		1,107,817,801	1,075,294,946
Common shares outstanding (in shares)		1,104,226,603	1,072,026,681
Treasury shares outstanding (in shares)		3,591,198	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	Jun. 30, 2018	Dec. 31, 2017
Assets
Loans held for sale, fair value	$ 643	$ 413
Loans and leases, fair value	$ 84	$ 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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest and fee income:
Loans and leases	$ 810	$ 700	$ 1,566	$ 1,376
Available-for-sale securities
Taxable	71	74	141	145
Tax-exempt	24	19	47	38
Held-to-maturity securities—taxable	53	44	107	89
Interest Income, Securities, Operating, Other, Taxable	7	4	13	9
Other	7	5	12	10
Total interest income	972	846	1,886	1,667
Interest expense:
Deposits	87	42	147	77
Short-term borrowings	14	5	33	11
Subordinated notes and other long-term debt	87	54	152	104
Total interest expense	188	101	332	192
Net interest income	784	745	1,554	1,475
Provision for credit losses	56	25	122	93
Net interest income after provision for credit losses	728	720	1,432	1,382
Service charges on deposit accounts	91	88	177	171
Cards and payment processing income	56	52	109	100
Mortgage banking income	28	32	54	64
Trust and investment management services	42	37	86	76
Insurance income	21	22	42	42
Capital markets fees	21	17	40	31
Bank owned life insurance income	17	15	32	33
Gain on sale of loans	15	12	23	25
Net gains on sales of securities	0	4	0	4
Other noninterest income	45	50	87	96
Total noninterest income	336	325	650	638
Personnel costs	396	392	772	774
Outside data processing and other services	69	75	142	162
Equipment	38	43	78	90
Net occupancy	35	53	76	120
Professional services	15	18	26	36
Marketing	18	19	26	33
Deposit and other insurance expense	18	20	36	41
Amortization of intangibles	13	14	27	29
Other noninterest expense	50	60	102	117
Total noninterest expense	652	694	1,285	1,402
Income before income taxes	412	351	797	618
Provision for income taxes	57	79	116	138
Net income	355	272	681	480
Dividends on preferred shares	21	19	33	38
Net income applicable to common shares	$ 334	$ 253	$ 648	$ 442
Average common shares—basic (in shares)	1,103,337	1,088,934	1,093,587	1,087,654
Average common shares—diluted (in shares)	1,122,612	1,108,527	1,123,646	1,108,572
Per common share:
Net income—basic (in usd per share)	$ 0.30	$ 0.23	$ 0.59	$ 0.41
Net income—diluted (in usd per share)	0.30	0.23	0.58	0.40
Cash dividends declared (in usd per share)	$ 0.11	$ 0.08	$ 0.22	$ 0.16
OTTI losses for the periods presented:
Total OTTI losses	$ 0	$ (4)	$ 0	$ (4)
Noncredit-related portion of loss recognized in OCI	0	0	0	0
Impairment losses recognized in earnings on available-for-sale securities	$ 0	$ (4)	$ 0	$ (4)

Condensed Consolidated Stateme5

Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 355	$ 272	$ 681	$ 480
Unrealized gains (losses) on available-for-sale securities:
Non-credit-related impairment recoveries (losses) on debt securities not expected to be sold	0	1	0	2
Unrealized net gains (losses) on available-for-sale securities arising during the period, net of reclassification for net realized gains and losses	53	(37)	203	(47)
Total unrealized gains (losses) on available-for-sale securities	(53)	38	(203)	49
Unrealized gains (losses) on cash flow hedging derivatives, net of reclassifications to income	0	1	0	1
Change in accumulated unrealized losses for pension and other post-retirement obligations	1	1	2	1
Other comprehensive income (loss), net of tax	(52)	40	(201)	51
Comprehensive income	$ 303	$ 312	$ 480	$ 531

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	Series E Preferred StockRetained Earnings (Deficit)	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	480					480
Other comprehensive income (loss)	51				51
Cash dividends declared:
Common stock, dividend	(174)					(174)
Preferred stock, dividend								$ (15)	$ (15)	$ (1)	$ (1)	$ (3)	$ (3)			$ (19)	$ (19)
Recognition of the fair value of share-based compensation	52		52
Other share-based compensation activity (in shares)		4,514
Other share-based compensation activity	(22)	$ 0	(15)			(7)
Other (in shares)		7		(193)
Other	(3)	$ 0	1	$ (4)		0
Balance, end of period (in shares) at Jun. 30, 2017		1,093,162		(3,146)
Balance, end of period at Jun. 30, 2017	10,654	$ 11	9,919	$ (31)	(350)	34	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	681					681
Other comprehensive income (loss)	(201)				(201)
Cash dividends declared:
Common stock, dividend	(243)					(243)
Preferred stock, dividend										$ (1)	$ (1)	$ (3)	$ (3)		$ (10)	$ (19)	$ (19)
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	$ 0	48
Conversion of Stock, Amount Converted	0		(363)				(363)
Conversion of Stock, Shares		30,330
Recognition of the fair value of share-based compensation	44		44
Other share-based compensation activity (in shares)		5,199
Other share-based compensation activity	(32)	$ 0	(28)			(4)
Other (in shares)				0
Other	(5)		0	$ (5)
Balance, end of period (in shares) at Jun. 30, 2018		1,107,817		(3,268)
Balance, end of period at Jun. 30, 2018	11,472	$ 11	$ 10,038	$ (40)	$ (730)	$ 990	$ 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	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash dividends declared:
Common stock, Cash dividend per share (in usd per share)	$ 0.22	$ 0.16
Series A Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	0	42.5
Series B Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	23.67	18.95
Series C Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	29.38	29.38
Series D Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	31.25	31.25
Series E Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	$ 2,042.50	$ 0

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities
Net income	$ 681	$ 480
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	122	93
Depreciation and amortization	228	211
Share-based compensation expense	44	52
Deferred income tax expense (benefit)	139	12
Net gains on sales of securities	0	(4)
Net change in:
Trading account securities	1	39
Loans held for sale	(274)	(221)
Accrued income and other assets	(170)	(58)
Accrued expense and other liabilities	(33)	(60)
Other, net	(136)	11
Net cash provided by (used in) operating activities	602	559
Investing activities
Change in interest bearing deposits in banks	56	19
Proceeds from:
Maturities and calls of available-for-sale securities	1,014	716
Maturities of held-to-maturity securities	350	523
Proceeds from Maturities, Prepayments and Calls of Other Investments	5	0
Sales of available-for-sale securities	381	406
Proceeds from Sale of Other Securities	0	6
Purchases of available-for-sale securities	(771)	(1,850)
Purchases of held-to-maturity securities	(71)	(9)
Payments To Acquire Other Securities	2	41
Net proceeds from sales of portfolio loans	310	259
Net loan and lease activity, excluding sales and purchases	(2,619)	(1,429)
Purchases of premises and equipment	(38)	(113)
Proceeds from sales of other real estate	13	18
Purchases of loans and leases	(104)	(94)
Other, net	18	9
Net cash provided by (used in) investing activities	(1,458)	(1,580)
Financing activities
Increase (decrease) in deposits	2,546	326
Increase (decrease) in short-term borrowings	(2,579)	838
Net proceeds from issuance of long-term debt	1,331	1,061
Maturity/redemption of long-term debt	(734)	(843)
Dividends paid on preferred stock	(30)	(38)
Dividends paid on common stock	(240)	(174)
Payments for Repurchase of Common Stock	(48)	0
Proceeds from stock options exercised	4	6
Net proceeds from issuance of preferred stock	495	0
Payments related to tax-withholding for share based compensation awards	(27)	(25)
Other, net	0	0
Net cash provided by (used for) financing activities	718	1,151
Increase (decrease) in cash a cash equivalents	(138)	130
Cash and cash equivalents at beginning of period	1,520	1,385
Cash and cash equivalents at end of period	1,382	1,515
Supplemental disclosures:
Interest paid	320	185
Income taxes paid (refunded)	(113)	54
Non-cash activities
Loans transferred to held-for-sale from portfolio	316	298
Loans transferred to portfolio from held-for-sale	34	1
Transfer of loans to OREO	10	17
Available For Sale Securities Transferred To Held To Maturity Securities	2,833	0
Held To Maturity Securities Transferred To Available For Sale	$ 2,707	$ 993

ACCOUNTING STANDARDS UPDATE

ACCOUNTING STANDARDS UPDATE	6 Months Ended
ACCOUNTING STANDARDS UPDATE	Jun. 30, 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. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. - See Footnote 12 for further detail impact on adoption. 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 using the modified retrospective approach. - 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. Standard Summary of guidance Effects on 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. 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. Except as mentioned in the paragraph below, 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 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 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. The amounts of right-of-use assets and corresponding lease liabilities recorded upon adoption will be based, primarily, on the present value of unpaid future minimum lease payments as of January 1, 2019. Those amounts will also be impacted by assumptions around renewals and/or extensions, and the interest rate used to discount those future lease obligations. As of December 31, 2017, the Company reported approximately $315 million in minimum lease payments due under such agreements January 1, 2019 forward. While these leases represent a majority of the leases within the scope of the standard, the lease portfolio is subject to change as a result of the execution of new leases and termination of existing leases prior to the effective date, as well as the identification of potential embedded and other leases. 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, finance, and risk management to evaluate the requirements of the new standard and the impact it will have on our processes. - Huntington is currently in the process of developing credit models as well as accounting, reporting, and governance processes to comply with the new credit reserve requirements. Standard Summary of guidance Effects on financial statements 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	6 Months Ended
BASIS OF PRESENTATION	Jun. 30, 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	6 Months Ended
LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES	Jun. 30, 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. The total balance that is netted against the loans pertaining to unamortized premiums, discounts, fees, and costs are $372 million and $334 million at June 30, 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 June 30, 2018 and December 31, 2017 . (dollar amounts in millions) June 30, 2018 December 31, 2017 Loans and leases: Commercial and industrial $ 28,850 $ 28,107 Commercial real estate 7,201 7,225 Automobile 12,390 12,100 Home equity 9,907 10,099 Residential mortgage 10,006 9,026 RV and marine finance 2,846 2,438 Other consumer 1,206 1,122 Loans and leases $ 72,406 $ 70,117 Allowance for loan and lease losses (741 ) (691 ) Net loans and leases $ 71,665 $ 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 June 30, 2018 and December 31, 2017 . (dollar amounts in millions) June 30, December 31, Commercial and industrial $ 207 $ 161 Commercial real estate 25 29 Automobile 4 6 Home equity 68 68 Residential mortgage 73 84 RV and marine finance 1 1 Other consumer — — Total nonaccrual loans $ 378 $ 349 The following table presents an aging analysis of loans and leases, including past due loans and leases, by loan class at June 30, 2018 and December 31, 2017 : June 30, 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 $ 47 $ 28 $ 63 $ 138 $ 28,712 $ — $ 28,850 $ 9 (2) Commercial real estate 2 12 6 20 7,181 — 7,201 — Automobile 71 15 7 93 12,297 — 12,390 6 Home equity 44 19 59 122 9,783 2 9,907 16 Residential mortgage 108 40 133 281 9,644 81 10,006 96 (3) RV and marine finance 8 2 1 11 2,834 1 2,846 1 Other consumer 12 6 4 22 1,184 — 1,206 4 Total loans and leases $ 292 $ 122 $ 273 $ 687 $ 71,635 $ 84 $ 72,406 $ 132 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 ALLL 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 and six-month periods ended June 30, 2018 and 2017 . (dollar amounts in millions) Commercial Consumer Total Three-month period ended June 30, 2018: ALLL balance, beginning of period $ 515 $ 206 $ 721 Loan charge-offs (12 ) (41 ) (53 ) Recoveries of loans previously charged-off 10 15 25 Provision for loan and lease losses 18 30 48 ALLL balance, end of period $ 531 $ 210 $ 741 AULC balance, beginning of period $ 82 $ 3 $ 85 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 8 — 8 AULC balance, end of period $ 90 $ 3 $ 93 ACL balance, end of period $ 621 $ 213 $ 834 Six-month period ended June 30, 2018: ALLL balance, beginning of period $ 482 $ 209 $ 691 Loan charge-offs (35 ) (91 ) (126 ) Recoveries of loans previously charged-off 30 30 60 Provision for loan and lease losses 54 62 116 ALLL balance, end of period $ 531 $ 210 $ 741 AULC balance, beginning of period $ 84 $ 3 $ 87 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 6 — 6 AULC balance, end of period $ 90 $ 3 $ 93 ACL balance, end of period $ 621 $ 213 $ 834 (dollar amounts in millions) Commercial Consumer Total Three-month period ended June 30, 2017: ALLL balance, beginning of period $ 480 $ 193 $ 673 Loan charge-offs (15 ) (42 ) (57 ) Recoveries of loans previously charged-off 6 15 21 Provision for loan and lease losses 4 27 31 ALLL balance, end of period $ 475 $ 193 $ 668 AULC balance, beginning of period $ 89 $ 3 $ 92 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (7 ) — (7 ) AULC balance, end of period $ 82 $ 3 $ 85 ACL balance, end of period $ 557 $ 196 $ 753 Six-month period ended June 30, 2017: ALLL balance, beginning of period $ 451 $ 187 $ 638 Loan charge-offs (39 ) (88 ) (127 ) Recoveries of loans previously charged-off 24 28 52 Provision for loan and lease losses 39 66 105 ALLL balance, end of period $ 475 $ 193 $ 668 AULC balance, beginning of period $ 87 $ 11 $ 98 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (5 ) (8 ) (13 ) AULC balance, end of period $ 82 $ 3 $ 85 ACL balance, end of period $ 557 $ 196 $ 753 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. Loans are generally assigned a category of " Pass " rating upon initial approval and subsequently updated as appropriate based on the borrowers financial performance. 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 June 30, 2018 and December 31, 2017 . June 30, 2018 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 26,940 $ 784 $ 1,115 $ 11 $ 28,850 Commercial real estate 6,895 181 123 2 7,201 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,338 $ 4,469 $ 1,296 $ 287 $ 12,390 Home equity 6,219 3,014 601 71 9,905 Residential mortgage 6,579 2,598 592 156 9,925 RV and marine finance 1,805 887 96 57 2,845 Other consumer 452 580 116 58 1,206 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 June 30, 2018 and December 31, 2017 . (dollar amounts in millions) Commercial Consumer Total ALLL at June 30, 2018: Portion of ALLL balance: Attributable to loans individually evaluated for impairment $ 39 $ 10 $ 49 Attributable to loans collectively evaluated for impairment 492 200 692 Total ALLL balance $ 531 $ 210 $ 741 Loan and Lease Ending Balances at June 30, 2018: (1) Portion of loan and lease ending balance: Individually evaluated for impairment $ 642 $ 599 $ 1,241 Collectively evaluated for impairment 35,409 35,672 71,081 Total loans and leases evaluated for impairment $ 36,051 $ 36,271 $ 72,322 (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 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) June 30, 2018 Three Months Ended Six Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 276 $ 305 $ — $ 259 $ 6 $ 268 $ 10 Commercial real estate 39 58 — 55 2 55 4 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 277 311 37 295 3 283 6 Commercial real estate 50 56 2 46 — 48 1 Automobile 36 40 2 37 1 36 1 Home equity 327 372 13 331 4 332 7 Residential mortgage 294 327 4 300 3 303 5 RV and marine finance 2 2 — 2 — 2 — Other consumer 9 9 3 7 — 7 — Total Commercial and industrial (3) 553 616 37 554 9 551 16 Commercial real estate (4) 89 114 2 101 2 103 5 Automobile (2) 36 40 2 37 1 36 1 Home equity (5) 327 372 13 331 4 332 7 Residential mortgage (5) 294 327 4 300 3 303 5 RV and marine finance (2) 2 2 — 2 — 2 — Other consumer (2) 9 9 3 7 — 7 — December 31, 2017 Three Months Ended Six Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 284 $ 311 $ — $ 263 $ 5 $ 268 $ 9 Commercial real estate 56 81 — 82 2 85 4 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 257 280 29 258 2 311 4 Commercial real estate 51 51 3 39 — 58 1 Automobile 36 40 2 33 1 32 1 Home equity 334 385 14 326 4 324 8 Residential mortgage 308 338 4 339 3 335 6 RV and marine finance 2 3 — 1 — 1 — Other consumer 8 8 2 4 — 4 — Total Commercial and industrial (3) 541 591 29 521 7 579 13 Commercial real estate (4) 107 132 3 121 2 143 5 Automobile (2) 36 40 2 33 1 32 1 Home equity (5) 334 385 14 326 4 324 8 Residential mortgage (5) 308 338 4 339 3 335 6 RV and marine finance (2) 2 3 — 1 — 1 — Other consumer (2) 8 8 2 4 — 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 June 30, 2018 and December 31, 2017 , C&I loans of $401 million and $382 million , respectively, were considered impaired due to their status as a TDR. (4) At June 30, 2018 and December 31, 2017 , CRE loans of $79 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 and six-month periods ended June 30, 2018 and 2017 . New Troubled Debt Restructurings During The Three-Month Period Ended (1) June 30, 2018 June 30, 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 4 — — 1 $ — $ — Amortization or maturity date change 264 171 (6 ) 228 168 (7 ) Other 1 — — 1 — — Total Commercial and industrial 269 171 (6 ) 230 168 (7 ) Commercial real estate: Interest rate reduction — — — — — — Amortization or maturity date change 36 43 (1 ) 19 25 — Other 2 — — — — — Total commercial real estate: 38 43 (1 ) 19 25 — Automobile: Interest rate reduction 10 — — 5 — — Amortization or maturity date change 382 3 — 334 3 — Chapter 7 bankruptcy 221 2 — 198 1 — Other — — — — — — Total Automobile 613 5 — 537 4 — Home equity: Interest rate reduction — — — 9 — — Amortization or maturity date change 113 8 — 135 8 (1 ) Chapter 7 bankruptcy 56 2 — 77 3 1 Other — — — 12 1 — Total Home equity 169 10 — 233 12 — Residential mortgage: Interest rate reduction 4 — — — — — Amortization or maturity date change 107 12 — 81 8 (1 ) Chapter 7 bankruptcy 7 — — 25 2 — Other 1 — — 5 1 — Total Residential mortgage 119 12 — 111 11 (1 ) RV and marine finance: Interest rate reduction — — — — — — Amortization or maturity date change 14 — — 10 — — Chapter 7 bankruptcy 26 — — 34 1 — Other — — — — — — Total RV and marine finance 40 — — 44 1 — Other consumer: Interest rate reduction 491 4 — — — — Amortization or maturity date change 1 — — 2 — — Chapter 7 bankruptcy 1 — — 2 — — Other — — — — — — Total Other consumer 493 4 — 4 — — Total new troubled debt restructurings 1,741 245 (7 ) 1,178 $ 221 $ (8 ) (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. New Troubled Debt Restructurings During The Six-Month Period Ended (1) June 30, 2018 June 30, 2017 (dollar amounts in millions) Number of Contracts Post-modification Outstanding Ending Balance (2) Financial effects of modification (3) Number of Contracts Post-modification Outstanding Ending Balance (2) Financial effects of modification (3) Commercial and industrial: Interest rate reduction 5 — — 2 $ — $ — Amortization or maturity date change 502 267 (8 ) 464 281 (8 ) Other 3 — — 4 — — Total Commercial and industrial 510 267 (8 ) 470 281 (8 ) Commercial real estate: Interest rate reduction — — — — — — Amortization or maturity date change 84 74 (1 ) 43 56 (1 ) Other 2 — — — — — Total commercial real estate: 86 74 (1 ) 43 56 (1 ) Automobile: Interest rate reduction 26 — — 19 — — Amortization or maturity date change 793 7 — 811 7 — Chapter 7 bankruptcy 421 4 — 438 4 — Other — — — — — — Total Automobile 1,240 11 — 1,268 11 — Home equity: Interest rate reduction 1 — — 17 1 — Amortization or maturity date change 212 14 (1 ) 241 14 (1 ) Chapter 7 bankruptcy 105 5 — 164 6 1 Other 7 1 — 70 4 — Total Home equity 325 20 (1 ) 492 25 — Residential mortgage: Interest rate reduction 4 — — 2 — — Amortization or maturity date change 179 20 — 180 19 — Chapter 7 bankruptcy 17 1 — 49 5 — Other 2 — — 21 3 — Total Residential mortgage 202 21 — 252 27 — RV and marine finance: Interest rate reduction — — — — — — Amortization or maturity date change 17 — — 24 — — Chapter 7 bankruptcy 42 1 — 49 1 — Other — — — — — — Total RV and marine finance 59 1 — 73 1 — Other consumer: Interest rate reduction 931 4 — 1 — — Amortization or maturity date change 1 — — 4 — — Chapter 7 bankruptcy 2 — — 3 — — Other — — — — — — Total Other consumer 934 4 — 8 — — Total new troubled debt restructurings 3,356 398 (10 ) 2,606 $ 401 $ (9 ) (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 June 30, 2018 and December 31, 2017 , these borrowings and advances are secured by $34.1 billion and $31.7 billion of loans and securities, respectively.

AVAILABLE-FOR-SALE SECURITIES

AVAILABLE-FOR-SALE SECURITIES	6 Months Ended
AVAILABLE-FOR-SALE SECURITIES	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
AVAILABLE-FOR-SALE AND OTHER SECURITIES	AVAILABLE-FOR-SALE SECURITIES Contractual maturities of available-for-sale securities at June 30, 2018 and December 31, 2017 were: June 30, 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 $ 6 $ 6 $ 5 $ 5 Total U.S. Treasury 6 6 5 5 Federal agencies: Residential CMO: After 1 year through 5 years — — 1 1 After 5 years through 10 years 44 42 90 89 After 10 years 7,510 7,208 6,570 6,394 Total Residential CMO 7,554 7,250 6,661 6,484 Residential MBS: After 1 year through 5 years 4 4 6 6 After 5 years through 10 years 31 30 7 8 After 10 years 643 625 1,358 1,353 Total Residential MBS 678 659 1,371 1,367 Commercial MBS: After 1 year through 5 years 69 66 23 22 After 5 years through 10 years 9 8 151 148 After 10 years 1,737 1,669 2,365 2,317 Total Commercial MBS 1,815 1,743 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 179 174 58 59 Total other agencies 188 183 69 70 Total U.S. Treasury, Federal agency, and other agency securities 10,241 9,841 10,645 10,413 Municipal securities: 1 year or less 164 164 103 103 After 1 year through 5 years 1,115 1,105 1,140 1,134 After 5 years through 10 years 1,702 1,674 1,709 1,704 After 10 years 845 822 940 937 Total municipal securities 3,826 3,765 3,892 3,878 Asset-backed securities: After 1 year through 5 years 40 39 80 80 After 5 years through 10 years 46 46 53 54 After 10 years 295 288 349 333 Total asset-backed securities 381 373 482 467 Corporate debt: 1 year or less 1 1 — — After 1 year through 5 years 75 74 73 74 After 5 years through 10 years 11 12 20 21 After 10 years — — 13 14 Total corporate debt 87 87 106 109 Other securities/Sovereign debt: 1 year or less — — 1 1 After 1 year through 5 years 4 4 1 1 Total other securities/Sovereign debt 4 4 2 2 Total available-for-sale securities $ 14,539 $ 14,070 $ 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 June 30, 2018 and December 31, 2017 : Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value June 30, 2018 U.S. Treasury $ 6 $ — $ — $ 6 Federal agencies: Residential CMO 7,554 — (304 ) 7,250 Residential MBS 678 — (19 ) 659 Commercial MBS 1,815 — (72 ) 1,743 Other agencies 188 — (5 ) 183 Total U.S. Treasury, Federal agency and other agency securities 10,241 — (400 ) 9,841 Municipal securities 3,826 12 (73 ) 3,765 Asset-backed securities 381 — (8 ) 373 Corporate debt 87 1 (1 ) 87 Other securities/Sovereign debt 4 — — 4 Total available-for-sale securities $ 14,539 $ 13 $ (482 ) $ 14,070 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 June 30, 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 June 30, 2018 Federal agencies: Residential CMO $ 3,217 $ (86 ) $ 3,988 $ (218 ) $ 7,205 $ (304 ) Residential MBS 638 (19 ) 12 — 650 (19 ) Commercial MBS 285 (9 ) 1,458 (63 ) 1,743 (72 ) Other agencies 88 (2 ) 85 (3 ) 173 (5 ) Total Federal Agency and other agency securities 4,228 (116 ) 5,543 (284 ) 9,771 (400 ) Municipal securities 2,306 (49 ) 723 (24 ) 3,029 (73 ) Asset-backed securities 210 (4 ) 102 (4 ) 312 (8 ) Corporate debt 61 (1 ) — — 61 (1 ) Other securities/Sovereign debt — — — — — — Total temporarily impaired securities $ 6,805 $ (170 ) $ 6,368 $ (312 ) $ 13,173 $ (482 ) 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 June 30, 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 $4.7 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 June 30, 2018 or December 31, 2017 . The following table is a summary of realized securities gains and losses for the three-month and six-month periods ended June 30, 2018 and 2017 , respectively. Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Gross gains on sales of securities $ 1 $ 4 $ 6 $ 5 Gross (losses) on sales of securities (1 ) — (6 ) (1 ) Net gain on sales of securities $ — $ 4 $ — $ 4 OTTI recognized in earnings — (4 ) — (4 ) Net securities gains (losses) $ — $ — $ — $ — Security Impairment Huntington evaluates the available-for-sale securities portfolio for impairment on a quarterly basis by conducting 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. As of June 30, 2018 , 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	6 Months Ended
HELD-TO-MATURITY SECURITIES	Jun. 30, 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. Listed below are the contractual maturities of held-to-maturity securities at June 30, 2018 and December 31, 2017 . June 30, 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 37 37 — — After 10 years 2,262 2,185 3,714 3,657 Total Residential CMO 2,299 2,222 3,714 3,657 Residential MBS: After 5 years through 10 years — — 28 28 After 10 years 1,677 1,623 1,021 1,016 Total Residential MBS 1,677 1,623 1,049 1,044 Commercial MBS: After 1 year through 5 years — — 38 37 After 5 years through 10 years 130 127 1 1 After 10 years 4,196 4,047 3,752 3,698 Total Commercial MBS 4,326 4,174 3,791 3,736 Other agencies: After 1 year through 5 years 13 13 7 8 After 5 years through 10 years 211 206 362 360 After 10 years 151 148 163 161 Total other agencies 375 367 532 529 Total Federal agencies and other agencies 8,677 8,386 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 $ 8,682 $ 8,391 $ 9,091 $ 8,971 The following table provides amortized cost, gross unrealized gains and losses, and fair value by investment category at June 30, 2018 and December 31, 2017 . Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value June 30, 2018 Federal agencies: Residential CMO $ 2,299 $ — $ (77 ) $ 2,222 Residential MBS 1,677 — (54 ) 1,623 Commercial MBS 4,326 — (152 ) 4,174 Other agencies 375 — (8 ) 367 Total Federal agencies and other agencies 8,677 — (291 ) 8,386 Municipal securities 5 — — 5 Total held-to-maturity securities $ 8,682 $ — $ (291 ) $ 8,391 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 June 30, 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 June 30, 2018 Federal agencies: Residential CMO $ 958 $ (29 ) $ 1,264 $ (48 ) $ 2,222 $ (77 ) Residential MBS 1,552 (54 ) — — 1,552 (54 ) Commercial MBS 3,458 (134 ) 716 (18 ) 4,174 (152 ) Other agencies 281 (6 ) 64 (2 ) 345 (8 ) Total Federal agencies and other agencies 6,249 (223 ) 2,044 (68 ) 8,293 (291 ) Municipal securities — — 5 — 5 — Total temporarily impaired securities $ 6,249 $ (223 ) $ 2,049 $ (68 ) $ 8,298 $ (291 ) 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 June 30, 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)	6 Months Ended
OTHER SECURITIES (Notes)	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
OTHER SECURITIES [Text Block]	OTHER SECURITIES June 30, 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 282 282 287 287 Federal Reserve Bank stock 294 294 294 294 Other securities, at fair value Mutual funds 19 19 18 18 Marketable equity securities 1 2 1 1 Total other securities $ 596 $ 597 $ 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	6 Months Ended
LOAN SALES AND SECURITIZATIONS	Jun. 30, 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 and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Residential mortgage loans sold with servicing retained $ 897 $ 798 $ 1,740 $ 1,646 Pretax gains resulting from above loan sales (1) 19 17 40 39 (1) Recorded in mortgage banking income. The following table summarizes the changes in MSRs recorded using the amortization method for the three-month and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 200 $ 178 $ 191 $ 172 New servicing assets created 11 8 20 18 Impairment recovery (charge) — (3 ) 7 (1 ) Amortization (7 ) (7 ) (14 ) (13 ) Carrying value, end of period $ 204 $ 176 $ 204 $ 176 Fair value, end of period $ 212 $ 177 $ 212 $ 177 Weighted-average life (years) 7.0 7.1 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 highly sensitive to movement 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 June 30, 2018 , and December 31, 2017 follows: June 30, 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) 8.50 % $ (5 ) $ (10 ) 8.30 % $ (5 ) $ (10 ) Spread over forward interest rate swap rates 952 bps (8 ) (15 ) 1,049 bps (7 ) (13 ) Additionally, at June 30, 2018 and 2017, Huntington held MSRs recorded using the fair value method of $11 million and $13 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 June 30, 2018 and 2017 , respectively. For the six-month periods ended June 30, 2018 and 2017 , total servicing, late and other ancillary fees included in mortgage banking income were $29 million and $28 million . The unpaid principal balance of residential mortgage loans serviced for third parties was $20.2 billion and $19.8 billion at June 30, 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 and six-month periods ended June 30, 2018 and 2017 , and the fair value at the end of each period were as follows: Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 6 $ 15 $ 8 $ 18 Amortization (1 ) (3 ) (3 ) (6 ) Carrying value, end of period $ 5 $ 12 $ 5 $ 12 Fair value, end of period $ 5 $ 12 $ 5 $ 12 Weighted-average contractual life (years) 3.2 3.8 3.2 3.8 Servicing income amounted to $3 million and $5 million for the three-month periods ending June 30, 2018 , and 2017 . For the six-month periods ended June 30, 2018 and 2017 , servicing income was $6 million and $10 million , respectively. The unpaid principal balance of automobile loans serviced for third parties was $0.8 billion and $1.0 billion at June 30, 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 and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 SBA loans sold with servicing retained $ 97 $ 88 $ 161 $ 165 Pretax gains resulting from above loan sales (1) 10 7 17 13 (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 and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 28 $ 21 $ 27 $ 21 New servicing assets created 3 4 5 6 Amortization (3 ) (2 ) (4 ) (4 ) Carrying value, end of period $ 28 $ 23 $ 28 $ 23 Fair value, end of period $ 33 $ 27 $ 33 $ 27 Weighted-average life (years) 3.4 3.3 3.4 3.3 Servicing income amounted to $3 million and $3 million for the three-month periods ending June 30, 2018 , and 2017 , respectively. For the six-month periods ended June 30, 2018 and 2017 , servicing income was $6 million and $5 million , respectively. The unpaid principal balance of SBA loans serviced for third parties was $1.5 billion and $1.4 billion at June 30, 2018 and December 31, 2017 , respectively.

LONG-TERM DEBT

LONG-TERM DEBT	6 Months Ended
LONG-TERM DEBT	Jun. 30, 2018
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT In May 2018, Huntington issued $500 million of senior notes at 99.686% of face value. The senior notes mature on May 15, 2025 and have a fixed coupon rate of 4.00% . The senior notes may be redeemed one month prior to the maturity date at 100% of principal plus accrued and unpaid interest. At June 30, 2018 , debt issuance costs of $1 million related to the note are reported on the balance sheet as a direct deduction from the face of the note. In May 2018, the Bank issued $750 million of senior notes at 99.774% of face value. The senior notes mature on May 14, 2021 and have a fixed coupon rate of 3.25% . The senior notes may be redeemed one month prior to the maturity date at 100% of principal plus accrued and unpaid interest. At June 30, 2018 , debt issuance costs of $2 million related to the note are reported on the balance sheet as a direct deduction from the face of the note.

OTHER COMPREHENSIVE INCOME

OTHER COMPREHENSIVE INCOME	6 Months Ended
OTHER COMPREHENSIVE INCOME	Jun. 30, 2018
Equity [Abstract]
OTHER COMPREHENSIVE INCOME	OTHER COMPREHENSIVE INCOME The components of Huntington's OCI for the three-month and six-month periods ended June 30, 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 (71 ) 15 (56 ) Less: Reclassification adjustment for net losses (gains) included in net income 3 — 3 Net change in unrealized holding gains (losses) on available-for-sale debt securities (68 ) 15 (53 ) Net change in pension and other post-retirement obligations 1 — 1 Total other comprehensive income (loss) $ (67 ) $ 15 $ (52 ) 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 $ 2 $ (1 ) $ 1 Unrealized holding gains (losses) on available-for-sale debt securities arising during the period 53 (19 ) 34 Less: Reclassification adjustment for net losses (gains) included in net income 4 (1 ) 3 Net change in unrealized holding gains (losses) on available-for-sale debt securities 59 (21 ) 38 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 — — — Net change in unrealized gains (losses) on derivatives used in cash flow hedging relationships 2 (1 ) 1 Net change in pension and other post-retirement obligations 1 — 1 Total other comprehensive income (loss) $ 62 $ (22 ) $ 40 Six 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 (277 ) 59 (218 ) Less: Reclassification adjustment for net losses (gains) included in net income 18 (3 ) 15 Net change in unrealized holding gains (losses) on available-for-sale debt securities (259 ) 56 (203 ) Net change in pension and other post-retirement obligations 2 — 2 Total other comprehensive income (loss) $ (257 ) $ 56 $ (201 ) Six 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 $ 3 $ (1 ) $ 2 Unrealized holding gains (losses) on available-for-sale debt securities arising during the period 62 (22 ) 40 Less: Reclassification adjustment for net losses (gains) included in net income 10 (3 ) 7 Net change in unrealized holding gains (losses) on available-for-sale debt securities 75 (26 ) 49 Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period — — — 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 2 (1 ) 1 Total other comprehensive income (loss) $ 78 $ (27 ) $ 51 Activity in accumulated OCI for the six -month periods ended June 30, 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 42 — — 42 Amounts reclassified from accumulated OCI to earnings 7 1 1 9 Period change 49 1 1 51 June 30, 2017 $ (144 ) $ (2 ) $ (204 ) $ (350 ) December 31, 2017 $ (278 ) $ — $ (250 ) $ (528 ) Cumulative-effect adjustments (ASU 2016-01) (1 ) — — (1 ) Other comprehensive income before reclassifications (218 ) — — (218 ) Amounts reclassified from accumulated OCI to earnings 15 — 2 17 Period change (203 ) — 2 (201 ) June 30, 2018 $ (482 ) $ — $ (248 ) $ (730 ) (1) AOCI amounts at June 30, 2018 , December 31, 2017 and June 30, 2017 include $144 million , $95 million and $98 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 and six-month periods ended June 30, 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) June 30, 2018 June 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (3 ) $ (2 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities — 2 Noninterest income - net gains (losses) on sale of securities OTTI recorded — (4 ) Noninterest income - net gains (losses) on sale of securities Total before tax (3 ) (4 ) Tax (expense) benefit — 1 Net of tax $ (3 ) $ (3 ) Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (1 ) $ (2 ) Noninterest income / expense (1) Net periodic benefit costs — 1 Noninterest income / expense (1) Total before tax (1 ) (1 ) Tax (expense) benefit — — Net of tax $ (1 ) $ (1 ) Reclassifications out of accumulated OCI Accumulated OCI components Amounts reclassified from accumulated OCI Location of net gain (loss) reclassified from accumulated OCI into earnings Six Months Ended (dollar amounts in millions) June 30, 2018 June 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (6 ) $ (6 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities (12 ) — Noninterest income - net gains (losses) on sale of securities OTTI recorded — (4 ) Noninterest income - net gains (losses) on sale of securities (18 ) (10 ) Total before tax 3 3 Tax (expense) benefit $ (15 ) $ (7 ) Net of tax Gains (losses) on cash flow hedging relationships: Interest rate contracts $ — $ (1 ) Interest income - loans and leases Interest rate contracts — — Noninterest income - other income — (1 ) Total before tax — — Tax (expense) benefit $ — $ (1 ) Net of tax Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (3 ) $ (3 ) Noninterest income / expense (1) Net periodic benefit costs 1 1 Noninterest income / expense (1) (2 ) (2 ) Total before tax — 1 Tax (expense) benefit $ (2 ) $ (1 ) Net of tax (1) The activity for 2018 and 2017 is recorded in Noninterest Income - other noninterest income and Noninterest Expense - personnel costs on the Condensed Consolidated Statements of Income, respectively.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	6 Months Ended
SHAREHOLDERS' EQUITY	Jun. 30, 2018
Equity [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY The following is a summary of Huntington's non-cumulative perpetual preferred stock outstanding as of June 30, 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 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 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.

EARNINGS PER SHARE

EARNINGS PER SHARE	6 Months Ended
EARNINGS PER SHARE	Jun. 30, 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 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 and six -month periods ended June 30, 2018 and 2017 was as follows: Three Months Ended Six Months Ended (dollar amounts in millions, except per share amounts) 2018 2017 2018 2017 Basic earnings per common share: Net income $ 355 $ 272 $ 681 $ 480 Preferred stock dividends (21 ) (19 ) (33 ) (38 ) Net income available to common shareholders $ 334 $ 253 $ 648 $ 442 Average common shares issued and outstanding (000) 1,103,337 1,088,934 1,093,587 1,087,654 Basic earnings per common share $ 0.30 $ 0.23 $ 0.59 $ 0.41 Diluted earnings per common share: Net income available to common shareholders $ 334 $ 253 $ 648 $ 442 Effect of assumed preferred stock conversion — — — — Net income applicable to diluted earnings per share $ 334 $ 253 $ 648 $ 442 Average common shares issued and outstanding (000) 1,103,337 1,088,934 1,093,587 1,087,654 Dilutive potential common shares: Stock options and restricted stock units and awards 15,803 16,329 17,830 17,734 Shares held in deferred compensation plans 3,472 3,108 3,350 3,030 Dilutive impact of Preferred Stock — — 8,879 — Other — 156 — 154 Dilutive potential common shares 19,275 19,593 30,059 20,918 Total diluted average common shares issued and outstanding (000) 1,122,612 1,108,527 1,123,646 1,108,572 Diluted earnings per common share $ 0.30 $ 0.23 $ 0.58 $ 0.40 There were approximately 2.5 million and 2.6 million of options to purchase shares of common stock outstanding for the three-month periods ended June 30, 2018 and 2017 , respectively. There were approximately 1.6 million and 1.8 million of options to purchase shares of common stock outstanding for the six-month periods ended June 30, 2018 and 2017. 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)	6 Months Ended
NON-INTEREST INCOME (Notes)	Jun. 30, 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 June 30, 2018 Six Months Ended June 30, 2018 Noninterest income Noninterest income from contracts with customers $ 217 $ 431 Noninterest income within the scope of other GAAP topics 119 219 Total noninterest income $ 336 $ 650 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 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 charges 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 does 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 fees 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 June 30, 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 are 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 includes fee income generated from personal, corporate and institutional customers. Huntington also provides investment management services, cash management services and 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. • Insurance income includes 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 18 . Three Months Ended June 30, 2018 (dollar amounts in millions) Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated Major Revenue Streams Service charges on deposit accounts $ 72 $ 16 $ 2 $ 1 $ — $ 91 Cards and payment processing income 49 3 — — — 52 Trust and investment management services 5 2 — 35 — 42 Insurance income 10 1 — 10 — 21 Other income 10 1 — — — 11 Net revenue from contracts with customers $ 146 $ 23 $ 2 $ 46 $ — $ 217 Noninterest income within the scope of other GAAP topics 41 57 — 2 19 119 Total noninterest income $ 187 $ 80 $ 2 $ 48 $ 19 $ 336 Six Months Ended June 30, 2018 (dollar amounts in millions) Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated Major Revenue Streams Service charges on deposit accounts $ 140 $ 32 $ 3 $ 2 $ — $ 177 Cards and payment processing income 96 5 — — — 101 Trust and investment management services 12 2 — 72 — 86 Insurance income 18 2 — 21 1 42 Other Income 20 1 1 2 1 25 Net revenue from contracts with customers $ 286 $ 42 $ 4 $ 97 $ 2 $ 431 Noninterest income within the scope of other GAAP topics 75 107 2 1 34 219 Total noninterest income $ 361 $ 149 $ 6 $ 98 $ 36 $ 650 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 June 30, 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 June 30, 2018 was determined to be immaterial.

BENEFIT PLANS

BENEFIT PLANS	6 Months Ended
BENEFIT PLANS	Jun. 30, 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 June 30, Three Months Ended June 30, (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 2 3 — — Net periodic (benefit) cost $ — $ (1 ) $ — $ (1 ) Pension Benefits (1) Post-Retirement Benefits (1) Six Months Ended June 30, Six Months Ended June 30, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ 2 $ 1 $ — $ — Interest cost 14 15 — — Expected return on plan assets (24 ) (28 ) — — Amortization of prior service cost — — (1 ) (1 ) Amortization of (gain) loss 4 4 — — Settlements 4 5 — — Net periodic (benefit) cost $ — $ (3 ) $ (1 ) $ (1 ) (1) The Pension and post-retirement (benefits) costs for 2018 and 2017 are recorded in Other noninterest income and Noninterest expense - personnel costs, respectively on the Condensed Consolidated Statements of Income. Huntington has a defined contribution plan that is available to eligible employees. Beginning January 1, 2018, Huntington increased the company match such that Huntington matches participant contributions 150% of the first 2% of base pay and 100% of the next 2%. Huntington's expense related to the defined contribution plans during the second quarter 2018 and 2017 was $17 million and $11 million , respectively. For the six-month period ended June 30, 2018 and 2017, expense related to the defined contribution plans was $28 million and $22 million , respectively.

FAIR VALUES OF ASSETS AND LIABI

FAIR VALUES OF ASSETS AND LIABILITIES	6 Months Ended
FAIR VALUES OF ASSETS AND LIABILITIES	Jun. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUES OF ASSETS AND LIABILITIES	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 and six-month periods ended June 30, 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 June 30, 2018 and December 31, 2017 are summarized below: Fair Value Measurements at Reporting Date Using Netting Adjustments (1) June 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Municipal securities $ — $ 5 $ — $ — $ 5 Other securities 78 2 — — 80 78 7 — — 85 Available-for-sale securities: U.S. Treasury securities 6 — — — 6 Residential CMOs — 7,250 — — 7,250 Residential MBS — 659 — — 659 Commercial MBS — 1,743 — — 1,743 Other agencies — 183 — — 183 Municipal securities — 587 3,178 — 3,765 Asset-backed securities — 373 — — 373 Corporate debt — 87 — — 87 Other securities/sovereign debt — 4 — — 4 6 10,886 3,178 — 14,070 Other securities 21 — — — 21 Loans held for sale — 643 — — 643 Loans held for investment — 50 34 — 84 MSRs — — 11 — 11 Derivative assets — 446 8 (275 ) 179 Liabilities Derivative liabilities — 399 7 (204 ) 202 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 and six-month periods ended June 30, 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 Loans held for investment Opening balance $ 12 $ — $ 3,230 $ 37 Transfers into Level 3 — — — — Transfers out of Level 3 (1) — (9 ) — — Total gains/losses for the period: Included in earnings (1 ) 10 (1 ) — Included in OCI — — (9 ) — Purchases/originations — — 86 — Sales — — — — Repayments — — — (3 ) Settlements — — (128 ) — Closing balance $ 11 $ 1 $ 3,178 $ 34 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (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 Opening balance $ 13 $ 3 $ 2,868 $ 59 $ 44 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — (2 ) — — — Total gains/losses for the period: Included in earnings — 2 (1 ) (3 ) 2 Included in OCI — — 12 6 — Purchases/originations — — 115 — — Sales — — — (19 ) — Repayments — — — — (2 ) Settlements — — (122 ) — — Closing balance $ 13 $ 3 $ 2,872 $ 43 $ 44 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ 3 $ 12 $ 6 $ — (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. 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) — (14 ) — — — Total gains/losses for the period: Included in earnings — 16 (2 ) (2 ) — Included in OCI — — (37 ) 11 — Purchases/originations — — 279 — — Sales — — — (33 ) — Repayments — — — — (4 ) Settlements — — (229 ) — — Closing balance $ 11 $ 1 $ 3,178 $ — $ 34 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ 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 Opening balance $ 14 $ (2 ) $ 2,798 $ 76 $ 48 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — (3 ) — — — Total gains/losses for the period: Included in earnings (1 ) 8 (3 ) (3 ) 1 Included in OCI — — 33 9 — Purchases/originations — — 248 — — Sales — — — (38 ) — Repayments — — — — (5 ) Settlements — — (204 ) (1 ) — Closing balance $ 13 $ 3 $ 2,872 $ 43 $ 44 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (1 ) $ 8 $ 33 $ 9 $ — (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 and six-month periods ended June 30, 2018 and 2017 : Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ (1 ) $ 10 $ — $ — Securities gains (losses) — — — — Other expense — — (1 ) — Total $ (1 ) $ 10 $ (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 Classification of gains and losses in earnings: Mortgage banking income $ — $ 2 $ — $ — $ — Securities gains (losses) — — (1 ) (3 ) — Noninterest income — — — — 2 Total $ — $ 2 $ (1 ) $ (3 ) $ 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 $ — $ 16 $ — $ — $ — Securities gains (losses) — — — (2 ) — Other expense — — (2 ) — — Total $ — $ 16 $ (2 ) $ (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 ) $ 8 $ — $ — $ — Securities gains (losses) — — (3 ) (3 ) — Noninterest income — — — — 1 Total $ (1 ) $ 8 $ (3 ) $ (3 ) $ 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: June 30, 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 $ 643 $ 625 $ 18 $ — $ — $ — Loans held for investment 84 93 (9 ) 7 8 (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 and six-month periods ended June 30, 2018 and 2017 . Net gains (losses) from fair value changes Net gains (losses) from fair value changes (dollar amounts in millions) Three Months Ended June 30, Six Months Ended June 30, Assets 2018 2017 2018 2017 Loans held for sale $ 5 $ 5 $ 3 $ 14 Loans held for investment — 2 — 1 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 six months ended June 30, 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 55 — — 55 — Other real estate owned 28 — — 28 (1 ) 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 June 30, 2018 and December 31, 2017 : Quantitative Information about Level 3 Fair Value Measurements at June 30, 2018 (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 6% - 44% (8%) Spread over forward interest rate 5% - 11% (8%) Derivative assets 8 Consensus Pricing Net market price -5% - 8% (2%) Estimated Pull through % 2% - 100% (90%) Derivative liabilities 7 Discounted cash flow Estimated conversion factor 163 % Estimated growth rate of Visa Class A shares 7 % Discount rate 3 % Timing of the resolution of the litigation 06/30/2020 Municipal securities 3,178 Discounted cash flow Discount rate 0% - 9% (4%) Cumulative default 0% - 64% (4%) Loss given default 5% - 90% (25%) Loans held for investment 34 Discounted cash flow Discount rate 7% - 19% (8%) Constant prepayment rate 2% - 22% (9%) Measured at fair value on a nonrecurring basis: Impaired loans 55 Appraisal value NA NA Other real estate owned 28 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 June 30, 2018 and December 31, 2017 : June 30, 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 1,423 — — 1,423 1,423 Trading account securities — — 85 85 85 Available-for-sale securities — — 14,070 14,070 14,070 Held-to-maturity securities 8,682 — — 8,682 8,391 Other securities 576 — 21 597 597 Loans held for sale — 66 643 709 713 Net loans and direct financing leases (1) 71,581 — 84 71,665 70,996 Derivatives — — 179 179 179 Financial Liabilities Deposits 79,587 — — 79,587 79,534 Short-term borrowings 2,442 — — 2,442 2,442 Long-term debt 9,726 — — 9,726 9,889 Derivatives — — 202 202 202 (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 June 30, 2018 and December 31, 2017 : Estimated Fair Value Measurements at Reporting Date Using June 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 78 $ 7 $ — $ 85 Available-for-sale securities 6 10,886 3,178 14,070 Held-to-maturity securities — 8,391 — 8,391 Other securities 21 — — 21 Loans held for sale — 643 70 713 Net loans and direct financing leases — 50 70,946 70,996 Financial Liabilities Deposits — 73,371 6,163 79,534 Short-term borrowings 2 — 2,440 2,442 Long-term debt — 9,416 473 9,889 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	6 Months Ended
DERIVATIVE FINANCIAL INSTRUMENTS	Jun. 30, 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 June 30, 2018 and December 31, 2017 . Amounts in the table below are presented gross without the impact of any net collateral arrangements. June 30, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Derivatives designated as Hedging Instruments Interest rate contracts $ 16 $ 66 $ 22 $ 121 Derivatives not designated as Hedging Instruments Interest rate contracts 268 176 187 100 Foreign exchange contracts 32 29 18 18 Commodities contracts 134 129 92 87 Equity contracts 4 6 3 5 Total Contracts $ 454 $ 406 $ 322 $ 331 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-month and six-month periods ended June 30, 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 June 30, 2018 Six Months Ended June 30, 2018 Interest rate contracts: Customer Capital markets fees $ 12 $ 19 Mortgage Banking Mortgage banking income — (8 ) Foreign exchange contracts Capital markets fees 7 12 Commodities contracts Capital markets fees — 2 Equity contracts Other noninterest expense (3 ) (3 ) Total $ 16 $ 22 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 securities into fixed rate securities. The following table presents the gross notional values of derivatives used in Huntington’s asset and liability management activities at June 30, 2018 and December 31, 2017 , identified by the underlying interest rate-sensitive instruments. June 30, 2018 (dollar amounts in millions) Fair Value Hedges Cash Flow Hedges Total Instruments associated with: Investment securities — 12 $ 12 Subordinated notes 375 — 375 Long-term debt 4,990 — 4,990 Total notional value at June 30, 2018 $ 5,365 $ 12 $ 5,377 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 June 30, 2018 and December 31, 2017 . June 30, 2018 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Asset conversion swaps Receive fixed—generic $ 12 1.7 $ — 2.20 % 2.07 % Liability conversion swaps Receive fixed—generic 5,365 2.2 (50 ) 1.93 2.27 Total swap portfolio at June 30, 2018 $ 5,377 2.2 $ (50 ) 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 adjustment to net interest income of $(15) million and $6 million for the three-month periods ended June 30, 2018 , and 2017 , respectively. The net amounts resulted in an adjustment to net interest income of $(14) million and $16 million for the six -month periods ended June 30, 2018 , and 2017 , respectively. During the second quarter of 2018, Huntington terminated $2.9 billion (notional value) of liability conversion swaps subsequent to de-designating these swaps as fair value hedges. The adjusted basis of the hedged item at termination was $149 million , which will be amortized over the remaining life of the long-term debt using the effective yield method. 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 and six-month periods ended June 30, 2018 and 2017 . Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Interest rate contracts Change in fair value of interest rate swaps hedging subordinated notes (1) 41 2 24 (2 ) Change in fair value of hedged subordinated notes (1) (42 ) (2 ) (24 ) 3 Change in fair value of interest rate swaps hedging other long-term debt (1) 93 16 42 6 Change in fair value of hedged other long-term debt (1) (90 ) (17 ) (37 ) (8 ) (1) Recognized in Interest expense—subordinated notes and other long-term debt in the Unaudited Condensed Consolidated Statements of Income. As of June 30, 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) June 30, 2018 June 30, 2018 Long-term debt $ 5,302 $ (55 ) The cumulative amount of fair value hedging adjustments remaining for any hedged assets and liabilities for which hedge accounting has been discontinued is $144 million at June 30, 2018 . 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 that economically hedge forward commitments to sell loans. The following table summarizes the derivative assets and liabilities used in mortgage banking activities: Derivatives used in mortgage banking activities June 30, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Interest rate lock agreements $ 8 $ — $ 6 $ — Forward trades and options — 5 1 — Total derivatives used in mortgage banking activities $ 8 $ 5 $ 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. All MSR hedging instruments matured during the second quarter of 2018. The notional value of the derivative financial instruments, corresponding trading liabilities, and net trading gains (losses) related to MSR hedging activity is summarized in the following table: MSR hedging activity (dollar amounts in millions) June 30, 2018 December 31, 2017 Notional Value $ — $ 188 Trading Liabilities — 3 Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Trading gains (losses) — 2 (8 ) 1 Trading gains (losses) are included in mortgage banking income in the Unaudited Condensed Consolidated Statement 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 enters 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 or price 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 June 30, 2018 and December 31, 2017 , were $99 million and $88 million , respectively. The total notional values of derivative financial instruments used by Huntington on behalf of customers, including offsetting derivatives, were $24 billion and $22 billion at June 30, 2018 and December 31, 2017 , respectively. Huntington’s credit risk from interest rate swaps used for trading purposes was $101 million and $119 million at the same dates, respectively. Visa ® -related Swaps 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 June 30, 2018 , the combined fair value of the swap liabilities of $7 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 14 . 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 June 30, 2018 and December 31, 2017 , aggregate credit risk associated with these derivatives, net of collateral that has been pledged by the counterparty, was $28 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 June 30, 2018 , Huntington pledged $64 million of investment securities and cash collateral to counterparties, while other counterparties pledged $200 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 June 30, 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 June 30, 2018 Derivatives $ 454 $ (275 ) $ 179 $ — $ (61 ) $ 118 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 June 30, 2018 Derivatives $ 406 $ (204 ) $ 202 $ — $ (20 ) $ 182 December 31, 2017 Derivatives 331 (245 ) 86 — (21 ) 65

VIEs

VIEs	6 Months Ended
VIEs	Jun. 30, 2018
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 June 30, 2018 , and December 31, 2017 : June 30, 2018 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 4 $ 1 $ 4 2015-1 Automobile Trust — — — Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 625 293 625 Other Investments 135 62 135 Total $ 778 $ 608 $ 764 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 June 30, 2018 follows: (dollar amounts in millions) Rate Principal amount of subordinated note/ debenture issued to trust (1) Investment in unconsolidated subsidiary Huntington Capital I 3.04 % (2) $ 70 $ 6 Huntington Capital II 2.96 (3) 32 3 Sky Financial Capital Trust III 3.74 (4) 72 2 Sky Financial Capital Trust IV 3.74 (4) 74 2 Camco Financial Trust 3.67 (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 June 30, 2018 , based on three-month LIBOR + 0.70% . (3) Variable effective rate at June 30, 2018 , based on three-month LIBOR + 0.625% . (4) Variable effective rate at June 30, 2018 , based on three-month LIBOR + 1.40% . (5) Variable effective rate at June 30, 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 accounted for 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 June 30, 2018 and December 31, 2017 . (dollar amounts in millions) June 30, December 31, Affordable housing tax credit investments $ 1,024 $ 996 Less: amortization (399 ) (360 ) Net affordable housing tax credit investments $ 625 $ 636 Unfunded commitments $ 293 $ 335 The following table presents other information relating to Huntington’s affordable housing tax credit investments for the three-month and six-month periods ended June 30, 2018 and 2017 . Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Tax credits and other tax benefits recognized $ 23 $ 23 $ 46 $ 46 Proportional amortization method Tax credit amortization expense included in provision for income taxes 20 17 39 34 Huntington recognized immaterial impairment losses for the three-month and six-month periods ended June 30, 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	6 Months Ended
COMMITMENTS AND CONTINGENT LIABILITIES	Jun. 30, 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 June 30, 2018 and December 31, 2017 , were as follows: (dollar amounts in millions) June 30, December 31, Contract amount representing credit risk Commitments to extend credit: Commercial $ 16,641 $ 16,219 Consumer 14,338 13,384 Commercial real estate 1,200 1,366 Standby letters of credit 601 510 Commercial letters-of-credit 27 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 $9 million and $10 million at June 30, 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 June 30, 2018 and December 31, 2017 , Huntington had commitments to sell residential real estate loans of $1.1 billion and $0.7 billion , respectively. These contracts mature in less than one year . Litigation and Regulatory Matters The following supplements the disclosure in Note 21 - Commitments and Contingencies to the Consolidated Financial Statements of the Corporation's 2017 Annual Report on Form 10-K. 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 June 30, 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, or in the prior commitments and contingencies disclosures, regarding the nature 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, and in the prior commitments and contingencies disclosures, 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 order approving the settlement became final on April 30, 2018. The settlement amount was paid in May 2018 and was within the Company's reserve for this matter.

SEGMENT REPORTING

SEGMENT REPORTING	6 Months Ended
SEGMENT REPORTING	Jun. 30, 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 June 30, 2018 , December 31, 2017 , and June 30, 2017 , reported results by business segment. Three Months Ended June 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 413 $ 229 $ 100 $ 46 $ (4 ) $ 784 Provision (benefit) for credit losses 27 18 10 1 — 56 Noninterest income 187 80 2 48 19 336 Noninterest expense 429 128 38 66 (9 ) 652 Provision (benefit) for income taxes 30 35 11 6 (25 ) 57 Net income (loss) $ 114 $ 128 $ 43 $ 21 $ 49 $ 355 2017 Net interest income 385 223 106 42 (11 ) 745 Provision (benefit) for credit losses 17 (5 ) 16 (3 ) — 25 Noninterest income 184 69 3 47 22 325 Noninterest expense 413 119 38 61 63 694 Provision (benefit) for income taxes 49 62 19 11 (62 ) 79 Net income (loss) $ 90 $ 116 $ 36 $ 20 $ 10 $ 272 Six Months Ended June 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 808 $ 449 $ 199 $ 91 $ 7 $ 1,554 Provision (benefit) for credit losses 59 39 23 1 — 122 Noninterest income 361 149 6 98 36 650 Noninterest expense 840 249 74 123 (1 ) 1,285 Provision (benefit) for income taxes 57 65 23 13 (42 ) 116 Net income (loss) $ 213 $ 245 $ 85 $ 52 $ 86 $ 681 2017 Net interest income $ 759 $ 452 $ 210 $ 83 $ (29 ) $ 1,475 Provision (benefit) for credit losses 51 16 26 — — 93 Noninterest income 355 134 8 94 47 638 Noninterest expense 826 236 74 124 142 1,402 Provision (benefit) for income taxes 83 117 41 19 (122 ) 138 Net income (loss) $ 154 $ 217 $ 77 $ 34 $ (2 ) $ 480 Assets at Deposits at (dollar amounts in millions) June 30, December 31, June 30, December 31, Consumer & Business Banking $ 27,013 $ 26,220 $ 48,186 $ 45,643 Commercial Banking 33,036 32,118 21,142 21,235 Vehicle Finance 18,590 17,865 340 358 RBHPCG 6,185 5,821 5,985 6,057 Treasury / Other 20,534 22,161 3,934 3,748 Total $ 105,358 $ 104,185 $ 79,587 $ 77,041

ACCOUNTING STANDARDS UPDATE (Po

ACCOUNTING STANDARDS UPDATE (Policies)	6 Months Ended
ACCOUNTING STANDARDS UPDATE (Policies)	Jun. 30, 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. - The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. - See Footnote 12 for further detail impact on adoption. 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 using the modified retrospective approach. - 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. Standard Summary of guidance Effects on 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. 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. Except as mentioned in the paragraph below, 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 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 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. The amounts of right-of-use assets and corresponding lease liabilities recorded upon adoption will be based, primarily, on the present value of unpaid future minimum lease payments as of January 1, 2019. Those amounts will also be impacted by assumptions around renewals and/or extensions, and the interest rate used to discount those future lease obligations. As of December 31, 2017, the Company reported approximately $315 million in minimum lease payments due under such agreements January 1, 2019 forward. While these leases represent a majority of the leases within the scope of the standard, the lease portfolio is subject to change as a result of the execution of new leases and termination of existing leases prior to the effective date, as well as the identification of potential embedded and other leases. 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, finance, and risk management to evaluate the requirements of the new standard and the impact it will have on our processes. - Huntington is currently in the process of developing credit models as well as accounting, reporting, and governance processes to comply with the new credit reserve requirements. Standard Summary of guidance Effects on financial statements 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 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 charges 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 does 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 fees 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 June 30, 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 are 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 includes fee income generated from personal, corporate and institutional customers. Huntington also provides investment management services, cash management services and 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. • Insurance income includes 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 28

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES (Tables)	6 Months Ended
LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES (Tables)	Jun. 30, 2018
Receivables [Abstract]
Loan and Lease Portfolio	The following table provides a detailed listing of Huntington’s loan and lease portfolio at June 30, 2018 and December 31, 2017 . (dollar amounts in millions) June 30, 2018 December 31, 2017 Loans and leases: Commercial and industrial $ 28,850 $ 28,107 Commercial real estate 7,201 7,225 Automobile 12,390 12,100 Home equity 9,907 10,099 Residential mortgage 10,006 9,026 RV and marine finance 2,846 2,438 Other consumer 1,206 1,122 Loans and leases $ 72,406 $ 70,117 Allowance for loan and lease losses (741 ) (691 ) Net loans and leases $ 71,665 $ 69,426
NALs and Past Due Loans	The following table presents NALs by loan class at June 30, 2018 and December 31, 2017 . (dollar amounts in millions) June 30, December 31, Commercial and industrial $ 207 $ 161 Commercial real estate 25 29 Automobile 4 6 Home equity 68 68 Residential mortgage 73 84 RV and marine finance 1 1 Other consumer — — Total nonaccrual loans $ 378 $ 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 June 30, 2018 and December 31, 2017 : June 30, 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 $ 47 $ 28 $ 63 $ 138 $ 28,712 $ — $ 28,850 $ 9 (2) Commercial real estate 2 12 6 20 7,181 — 7,201 — Automobile 71 15 7 93 12,297 — 12,390 6 Home equity 44 19 59 122 9,783 2 9,907 16 Residential mortgage 108 40 133 281 9,644 81 10,006 96 (3) RV and marine finance 8 2 1 11 2,834 1 2,846 1 Other consumer 12 6 4 22 1,184 — 1,206 4 Total loans and leases $ 292 $ 122 $ 273 $ 687 $ 71,635 $ 84 $ 72,406 $ 132 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 and six-month periods ended June 30, 2018 and 2017 . (dollar amounts in millions) Commercial Consumer Total Three-month period ended June 30, 2018: ALLL balance, beginning of period $ 515 $ 206 $ 721 Loan charge-offs (12 ) (41 ) (53 ) Recoveries of loans previously charged-off 10 15 25 Provision for loan and lease losses 18 30 48 ALLL balance, end of period $ 531 $ 210 $ 741 AULC balance, beginning of period $ 82 $ 3 $ 85 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 8 — 8 AULC balance, end of period $ 90 $ 3 $ 93 ACL balance, end of period $ 621 $ 213 $ 834 Six-month period ended June 30, 2018: ALLL balance, beginning of period $ 482 $ 209 $ 691 Loan charge-offs (35 ) (91 ) (126 ) Recoveries of loans previously charged-off 30 30 60 Provision for loan and lease losses 54 62 116 ALLL balance, end of period $ 531 $ 210 $ 741 AULC balance, beginning of period $ 84 $ 3 $ 87 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 6 — 6 AULC balance, end of period $ 90 $ 3 $ 93 ACL balance, end of period $ 621 $ 213 $ 834 (dollar amounts in millions) Commercial Consumer Total Three-month period ended June 30, 2017: ALLL balance, beginning of period $ 480 $ 193 $ 673 Loan charge-offs (15 ) (42 ) (57 ) Recoveries of loans previously charged-off 6 15 21 Provision for loan and lease losses 4 27 31 ALLL balance, end of period $ 475 $ 193 $ 668 AULC balance, beginning of period $ 89 $ 3 $ 92 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (7 ) — (7 ) AULC balance, end of period $ 82 $ 3 $ 85 ACL balance, end of period $ 557 $ 196 $ 753 Six-month period ended June 30, 2017: ALLL balance, beginning of period $ 451 $ 187 $ 638 Loan charge-offs (39 ) (88 ) (127 ) Recoveries of loans previously charged-off 24 28 52 Provision for loan and lease losses 39 66 105 ALLL balance, end of period $ 475 $ 193 $ 668 AULC balance, beginning of period $ 87 $ 11 $ 98 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (5 ) (8 ) (13 ) AULC balance, end of period $ 82 $ 3 $ 85 ACL balance, end of period $ 557 $ 196 $ 753
Loan and lease balances by credit quality indicator	The following table presents each loan and lease class by credit quality indicator at June 30, 2018 and December 31, 2017 . June 30, 2018 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 26,940 $ 784 $ 1,115 $ 11 $ 28,850 Commercial real estate 6,895 181 123 2 7,201 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,338 $ 4,469 $ 1,296 $ 287 $ 12,390 Home equity 6,219 3,014 601 71 9,905 Residential mortgage 6,579 2,598 592 156 9,925 RV and marine finance 1,805 887 96 57 2,845 Other consumer 452 580 116 58 1,206 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 June 30, 2018 and December 31, 2017 . (dollar amounts in millions) Commercial Consumer Total ALLL at June 30, 2018: Portion of ALLL balance: Attributable to loans individually evaluated for impairment $ 39 $ 10 $ 49 Attributable to loans collectively evaluated for impairment 492 200 692 Total ALLL balance $ 531 $ 210 $ 741 Loan and Lease Ending Balances at June 30, 2018: (1) Portion of loan and lease ending balance: Individually evaluated for impairment $ 642 $ 599 $ 1,241 Collectively evaluated for impairment 35,409 35,672 71,081 Total loans and leases evaluated for impairment $ 36,051 $ 36,271 $ 72,322 (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 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) June 30, 2018 Three Months Ended Six Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 276 $ 305 $ — $ 259 $ 6 $ 268 $ 10 Commercial real estate 39 58 — 55 2 55 4 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 277 311 37 295 3 283 6 Commercial real estate 50 56 2 46 — 48 1 Automobile 36 40 2 37 1 36 1 Home equity 327 372 13 331 4 332 7 Residential mortgage 294 327 4 300 3 303 5 RV and marine finance 2 2 — 2 — 2 — Other consumer 9 9 3 7 — 7 — Total Commercial and industrial (3) 553 616 37 554 9 551 16 Commercial real estate (4) 89 114 2 101 2 103 5 Automobile (2) 36 40 2 37 1 36 1 Home equity (5) 327 372 13 331 4 332 7 Residential mortgage (5) 294 327 4 300 3 303 5 RV and marine finance (2) 2 2 — 2 — 2 — Other consumer (2) 9 9 3 7 — 7 — December 31, 2017 Three Months Ended Six Months Ended (dollar amounts in millions) Ending Balance Unpaid Principal Balance (6) Related Allowance Average Balance Interest Income Recognized Average Balance Interest Income Recognized With no related allowance recorded: Commercial and industrial $ 284 $ 311 $ — $ 263 $ 5 $ 268 $ 9 Commercial real estate 56 81 — 82 2 85 4 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 257 280 29 258 2 311 4 Commercial real estate 51 51 3 39 — 58 1 Automobile 36 40 2 33 1 32 1 Home equity 334 385 14 326 4 324 8 Residential mortgage 308 338 4 339 3 335 6 RV and marine finance 2 3 — 1 — 1 — Other consumer 8 8 2 4 — 4 — Total Commercial and industrial (3) 541 591 29 521 7 579 13 Commercial real estate (4) 107 132 3 121 2 143 5 Automobile (2) 36 40 2 33 1 32 1 Home equity (5) 334 385 14 326 4 324 8 Residential mortgage (5) 308 338 4 339 3 335 6 RV and marine finance (2) 2 3 — 1 — 1 — Other consumer (2) 8 8 2 4 — 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 June 30, 2018 and December 31, 2017 , C&I loans of $401 million and $382 million , respectively, were considered impaired due to their status as a TDR. (4) At June 30, 2018 and December 31, 2017 , CRE loans of $79 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 and six-month periods ended June 30, 2018 and 2017 . New Troubled Debt Restructurings During The Three-Month Period Ended (1) June 30, 2018 June 30, 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 4 — — 1 $ — $ — Amortization or maturity date change 264 171 (6 ) 228 168 (7 ) Other 1 — — 1 — — Total Commercial and industrial 269 171 (6 ) 230 168 (7 ) Commercial real estate: Interest rate reduction — — — — — — Amortization or maturity date change 36 43 (1 ) 19 25 — Other 2 — — — — — Total commercial real estate: 38 43 (1 ) 19 25 — Automobile: Interest rate reduction 10 — — 5 — — Amortization or maturity date change 382 3 — 334 3 — Chapter 7 bankruptcy 221 2 — 198 1 — Other — — — — — — Total Automobile 613 5 — 537 4 — Home equity: Interest rate reduction — — — 9 — — Amortization or maturity date change 113 8 — 135 8 (1 ) Chapter 7 bankruptcy 56 2 — 77 3 1 Other — — — 12 1 — Total Home equity 169 10 — 233 12 — Residential mortgage: Interest rate reduction 4 — — — — — Amortization or maturity date change 107 12 — 81 8 (1 ) Chapter 7 bankruptcy 7 — — 25 2 — Other 1 — — 5 1 — Total Residential mortgage 119 12 — 111 11 (1 ) RV and marine finance: Interest rate reduction — — — — — — Amortization or maturity date change 14 — — 10 — — Chapter 7 bankruptcy 26 — — 34 1 — Other — — — — — — Total RV and marine finance 40 — — 44 1 — Other consumer: Interest rate reduction 491 4 — — — — Amortization or maturity date change 1 — — 2 — — Chapter 7 bankruptcy 1 — — 2 — — Other — — — — — — Total Other consumer 493 4 — 4 — — Total new troubled debt restructurings 1,741 245 (7 ) 1,178 $ 221 $ (8 ) (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. New Troubled Debt Restructurings During The Six-Month Period Ended (1) June 30, 2018 June 30, 2017 (dollar amounts in millions) Number of Contracts Post-modification Outstanding Ending Balance (2) Financial effects of modification (3) Number of Contracts Post-modification Outstanding Ending Balance (2) Financial effects of modification (3) Commercial and industrial: Interest rate reduction 5 — — 2 $ — $ — Amortization or maturity date change 502 267 (8 ) 464 281 (8 ) Other 3 — — 4 — — Total Commercial and industrial 510 267 (8 ) 470 281 (8 ) Commercial real estate: Interest rate reduction — — — — — — Amortization or maturity date change 84 74 (1 ) 43 56 (1 ) Other 2 — — — — — Total commercial real estate: 86 74 (1 ) 43 56 (1 ) Automobile: Interest rate reduction 26 — — 19 — — Amortization or maturity date change 793 7 — 811 7 — Chapter 7 bankruptcy 421 4 — 438 4 — Other — — — — — — Total Automobile 1,240 11 — 1,268 11 — Home equity: Interest rate reduction 1 — — 17 1 — Amortization or maturity date change 212 14 (1 ) 241 14 (1 ) Chapter 7 bankruptcy 105 5 — 164 6 1 Other 7 1 — 70 4 — Total Home equity 325 20 (1 ) 492 25 — Residential mortgage: Interest rate reduction 4 — — 2 — — Amortization or maturity date change 179 20 — 180 19 — Chapter 7 bankruptcy 17 1 — 49 5 — Other 2 — — 21 3 — Total Residential mortgage 202 21 — 252 27 — RV and marine finance: Interest rate reduction — — — — — — Amortization or maturity date change 17 — — 24 — — Chapter 7 bankruptcy 42 1 — 49 1 — Other — — — — — — Total RV and marine finance 59 1 — 73 1 — Other consumer: Interest rate reduction 931 4 — 1 — — Amortization or maturity date change 1 — — 4 — — Chapter 7 bankruptcy 2 — — 3 — — Other — — — — — — Total Other consumer 934 4 — 8 — — Total new troubled debt restructurings 3,356 398 (10 ) 2,606 $ 401 $ (9 ) (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)	6 Months Ended
AVAILABLE-FOR-SALE SECURITIES (Tables)	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Contractual maturities of investment securities	ontractual maturities of available-for-sale securities at June 30, 2018 and December 31, 2017 were: June 30, 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 $ 6 $ 6 $ 5 $ 5 Total U.S. Treasury 6 6 5 5 Federal agencies: Residential CMO: After 1 year through 5 years — — 1 1 After 5 years through 10 years 44 42 90 89 After 10 years 7,510 7,208 6,570 6,394 Total Residential CMO 7,554 7,250 6,661 6,484 Residential MBS: After 1 year through 5 years 4 4 6 6 After 5 years through 10 years 31 30 7 8 After 10 years 643 625 1,358 1,353 Total Residential MBS 678 659 1,371 1,367 Commercial MBS: After 1 year through 5 years 69 66 23 22 After 5 years through 10 years 9 8 151 148 After 10 years 1,737 1,669 2,365 2,317 Total Commercial MBS 1,815 1,743 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 179 174 58 59 Total other agencies 188 183 69 70 Total U.S. Treasury, Federal agency, and other agency securities 10,241 9,841 10,645 10,413 Municipal securities: 1 year or less 164 164 103 103 After 1 year through 5 years 1,115 1,105 1,140 1,134 After 5 years through 10 years 1,702 1,674 1,709 1,704 After 10 years 845 822 940 937 Total municipal securities 3,826 3,765 3,892 3,878 Asset-backed securities: After 1 year through 5 years 40 39 80 80 After 5 years through 10 years 46 46 53 54 After 10 years 295 288 349 333 Total asset-backed securities 381 373 482 467 Corporate debt: 1 year or less 1 1 — — After 1 year through 5 years 75 74 73 74 After 5 years through 10 years 11 12 20 21 After 10 years — — 13 14 Total corporate debt 87 87 106 109 Other securities/Sovereign debt: 1 year or less — — 1 1 After 1 year through 5 years 4 4 1 1 Total other securities/Sovereign debt 4 4 2 2 Total available-for-sale securities $ 14,539 $ 14,070 $ 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 June 30, 2018 and December 31, 2017 : Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value June 30, 2018 U.S. Treasury $ 6 $ — $ — $ 6 Federal agencies: Residential CMO 7,554 — (304 ) 7,250 Residential MBS 678 — (19 ) 659 Commercial MBS 1,815 — (72 ) 1,743 Other agencies 188 — (5 ) 183 Total U.S. Treasury, Federal agency and other agency securities 10,241 — (400 ) 9,841 Municipal securities 3,826 12 (73 ) 3,765 Asset-backed securities 381 — (8 ) 373 Corporate debt 87 1 (1 ) 87 Other securities/Sovereign debt 4 — — 4 Total available-for-sale securities $ 14,539 $ 13 $ (482 ) $ 14,070 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 June 30, 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 June 30, 2018 Federal agencies: Residential CMO $ 3,217 $ (86 ) $ 3,988 $ (218 ) $ 7,205 $ (304 ) Residential MBS 638 (19 ) 12 — 650 (19 ) Commercial MBS 285 (9 ) 1,458 (63 ) 1,743 (72 ) Other agencies 88 (2 ) 85 (3 ) 173 (5 ) Total Federal Agency and other agency securities 4,228 (116 ) 5,543 (284 ) 9,771 (400 ) Municipal securities 2,306 (49 ) 723 (24 ) 3,029 (73 ) Asset-backed securities 210 (4 ) 102 (4 ) 312 (8 ) Corporate debt 61 (1 ) — — 61 (1 ) Other securities/Sovereign debt — — — — — — Total temporarily impaired securities $ 6,805 $ (170 ) $ 6,368 $ (312 ) $ 13,173 $ (482 ) 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 and six-month periods ended June 30, 2018 and 2017 , respectively. Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Gross gains on sales of securities $ 1 $ 4 $ 6 $ 5 Gross (losses) on sales of securities (1 ) — (6 ) (1 ) Net gain on sales of securities $ — $ 4 $ — $ 4 OTTI recognized in earnings — (4 ) — (4 ) Net securities gains (losses) $ — $ — $ — $ —

HELD-TO-MATURITY SECURITIES (Ta

HELD-TO-MATURITY SECURITIES (Tables)	6 Months Ended
HELD-TO-MATURITY SECURITIES (Tables)	Jun. 30, 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 June 30, 2018 and December 31, 2017 . June 30, 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 37 37 — — After 10 years 2,262 2,185 3,714 3,657 Total Residential CMO 2,299 2,222 3,714 3,657 Residential MBS: After 5 years through 10 years — — 28 28 After 10 years 1,677 1,623 1,021 1,016 Total Residential MBS 1,677 1,623 1,049 1,044 Commercial MBS: After 1 year through 5 years — — 38 37 After 5 years through 10 years 130 127 1 1 After 10 years 4,196 4,047 3,752 3,698 Total Commercial MBS 4,326 4,174 3,791 3,736 Other agencies: After 1 year through 5 years 13 13 7 8 After 5 years through 10 years 211 206 362 360 After 10 years 151 148 163 161 Total other agencies 375 367 532 529 Total Federal agencies and other agencies 8,677 8,386 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 $ 8,682 $ 8,391 $ 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 June 30, 2018 and December 31, 2017 . Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value June 30, 2018 Federal agencies: Residential CMO $ 2,299 $ — $ (77 ) $ 2,222 Residential MBS 1,677 — (54 ) 1,623 Commercial MBS 4,326 — (152 ) 4,174 Other agencies 375 — (8 ) 367 Total Federal agencies and other agencies 8,677 — (291 ) 8,386 Municipal securities 5 — — 5 Total held-to-maturity securities $ 8,682 $ — $ (291 ) $ 8,391 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 June 30, 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 June 30, 2018 Federal agencies: Residential CMO $ 958 $ (29 ) $ 1,264 $ (48 ) $ 2,222 $ (77 ) Residential MBS 1,552 (54 ) — — 1,552 (54 ) Commercial MBS 3,458 (134 ) 716 (18 ) 4,174 (152 ) Other agencies 281 (6 ) 64 (2 ) 345 (8 ) Total Federal agencies and other agencies 6,249 (223 ) 2,044 (68 ) 8,293 (291 ) Municipal securities — — 5 — 5 — Total temporarily impaired securities $ 6,249 $ (223 ) $ 2,049 $ (68 ) $ 8,298 $ (291 ) 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)	6 Months Ended
OTHER SECURITIES (Tables)	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Other Securities [Table Text Block]	June 30, 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 282 282 287 287 Federal Reserve Bank stock 294 294 294 294 Other securities, at fair value Mutual funds 19 19 18 18 Marketable equity securities 1 2 1 1 Total other securities $ 596 $ 597 $ 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)	6 Months Ended
LOAN SALES AND SECURITIZATIONS (Tables)	Jun. 30, 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 and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Residential mortgage loans sold with servicing retained $ 897 $ 798 $ 1,740 $ 1,646 Pretax gains resulting from above loan sales (1) 19 17 40 39 (1) Recorded in mortgage banking income. The following table summarizes activity relating to SBA loans sold with servicing retained for the three-month and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 SBA loans sold with servicing retained $ 97 $ 88 $ 161 $ 165 Pretax gains resulting from above loan sales (1) 10 7 17 13 (1) Recorded in gain on sale of loans.
Summarizes activity relating to loans sold with servicing retained using the fair value method	The following table summarizes the changes in the carrying value of the servicing asset for the three-month and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 28 $ 21 $ 27 $ 21 New servicing assets created 3 4 5 6 Amortization (3 ) (2 ) (4 ) (4 ) Carrying value, end of period $ 28 $ 23 $ 28 $ 23 Fair value, end of period $ 33 $ 27 $ 33 $ 27 Weighted-average life (years) 3.4 3.3 3.4 3.3 Changes in the carrying value of automobile loan servicing rights for the three-month and six-month periods ended June 30, 2018 and 2017 , and the fair value at the end of each period were as follows: Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 6 $ 15 $ 8 $ 18 Amortization (1 ) (3 ) (3 ) (6 ) Carrying value, end of period $ 5 $ 12 $ 5 $ 12 Fair value, end of period $ 5 $ 12 $ 5 $ 12 Weighted-average contractual life (years) 3.2 3.8 3.2 3.8
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 and six-month periods ended June 30, 2018 and 2017 : Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 200 $ 178 $ 191 $ 172 New servicing assets created 11 8 20 18 Impairment recovery (charge) — (3 ) 7 (1 ) Amortization (7 ) (7 ) (14 ) (13 ) Carrying value, end of period $ 204 $ 176 $ 204 $ 176 Fair value, end of period $ 212 $ 177 $ 212 $ 177 Weighted-average life (years) 7.0 7.1 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 June 30, 2018 , and December 31, 2017 follows: June 30, 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) 8.50 % $ (5 ) $ (10 ) 8.30 % $ (5 ) $ (10 ) Spread over forward interest rate swap rates 952 bps (8 ) (15 ) 1,049 bps (7 ) (13 )

OTHER COMPREHENSIVE INCOME (Tab

OTHER COMPREHENSIVE INCOME (Tables)	6 Months Ended
OTHER COMPREHENSIVE INCOME (Tables)	Jun. 30, 2018
Equity [Abstract]
Components of other comprehensive income	The components of Huntington's OCI for the three-month and six-month periods ended June 30, 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 (71 ) 15 (56 ) Less: Reclassification adjustment for net losses (gains) included in net income 3 — 3 Net change in unrealized holding gains (losses) on available-for-sale debt securities (68 ) 15 (53 ) Net change in pension and other post-retirement obligations 1 — 1 Total other comprehensive income (loss) $ (67 ) $ 15 $ (52 ) 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 $ 2 $ (1 ) $ 1 Unrealized holding gains (losses) on available-for-sale debt securities arising during the period 53 (19 ) 34 Less: Reclassification adjustment for net losses (gains) included in net income 4 (1 ) 3 Net change in unrealized holding gains (losses) on available-for-sale debt securities 59 (21 ) 38 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 — — — Net change in unrealized gains (losses) on derivatives used in cash flow hedging relationships 2 (1 ) 1 Net change in pension and other post-retirement obligations 1 — 1 Total other comprehensive income (loss) $ 62 $ (22 ) $ 40 Six 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 (277 ) 59 (218 ) Less: Reclassification adjustment for net losses (gains) included in net income 18 (3 ) 15 Net change in unrealized holding gains (losses) on available-for-sale debt securities (259 ) 56 (203 ) Net change in pension and other post-retirement obligations 2 — 2 Total other comprehensive income (loss) $ (257 ) $ 56 $ (201 ) Six 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 $ 3 $ (1 ) $ 2 Unrealized holding gains (losses) on available-for-sale debt securities arising during the period 62 (22 ) 40 Less: Reclassification adjustment for net losses (gains) included in net income 10 (3 ) 7 Net change in unrealized holding gains (losses) on available-for-sale debt securities 75 (26 ) 49 Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period — — — 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 2 (1 ) 1 Total other comprehensive income (loss) $ 78 $ (27 ) $ 51
Activity in accumulated other comprehensive income, net of tax	ctivity in accumulated OCI for the six -month periods ended June 30, 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 42 — — 42 Amounts reclassified from accumulated OCI to earnings 7 1 1 9 Period change 49 1 1 51 June 30, 2017 $ (144 ) $ (2 ) $ (204 ) $ (350 ) December 31, 2017 $ (278 ) $ — $ (250 ) $ (528 ) Cumulative-effect adjustments (ASU 2016-01) (1 ) — — (1 ) Other comprehensive income before reclassifications (218 ) — — (218 ) Amounts reclassified from accumulated OCI to earnings 15 — 2 17 Period change (203 ) — 2 (201 ) June 30, 2018 $ (482 ) $ — $ (248 ) $ (730 )
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 and six-month periods ended June 30, 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) June 30, 2018 June 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (3 ) $ (2 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities — 2 Noninterest income - net gains (losses) on sale of securities OTTI recorded — (4 ) Noninterest income - net gains (losses) on sale of securities Total before tax (3 ) (4 ) Tax (expense) benefit — 1 Net of tax $ (3 ) $ (3 ) Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (1 ) $ (2 ) Noninterest income / expense (1) Net periodic benefit costs — 1 Noninterest income / expense (1) Total before tax (1 ) (1 ) Tax (expense) benefit — — Net of tax $ (1 ) $ (1 ) Reclassifications out of accumulated OCI Accumulated OCI components Amounts reclassified from accumulated OCI Location of net gain (loss) reclassified from accumulated OCI into earnings Six Months Ended (dollar amounts in millions) June 30, 2018 June 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (6 ) $ (6 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities (12 ) — Noninterest income - net gains (losses) on sale of securities OTTI recorded — (4 ) Noninterest income - net gains (losses) on sale of securities (18 ) (10 ) Total before tax 3 3 Tax (expense) benefit $ (15 ) $ (7 ) Net of tax Gains (losses) on cash flow hedging relationships: Interest rate contracts $ — $ (1 ) Interest income - loans and leases Interest rate contracts — — Noninterest income - other income — (1 ) Total before tax — — Tax (expense) benefit $ — $ (1 ) Net of tax Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (3 ) $ (3 ) Noninterest income / expense (1) Net periodic benefit costs 1 1 Noninterest income / expense (1) (2 ) (2 ) Total before tax — 1 Tax (expense) benefit $ (2 ) $ (1 ) Net of tax (1) The activity for 2018 and 2017 is recorded in Noninterest Income - other noninterest income and Noninterest Expense - personnel costs on the Condensed Consolidated Statements of Income, respectively.

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	6 Months Ended
SHAREHOLDERS' EQUITY (Tables)	Jun. 30, 2018
Equity [Abstract]
Schedule of Preferred Stock	The following is a summary of Huntington's non-cumulative perpetual preferred stock outstanding as of June 30, 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)	6 Months Ended
EARNINGS PER SHARE (Tables)	Jun. 30, 2018
Earnings Per Share [Abstract]
Basic and diluted earnings loss per share	The calculation of basic and diluted earnings per share for the three and six -month periods ended June 30, 2018 and 2017 was as follows: Three Months Ended Six Months Ended (dollar amounts in millions, except per share amounts) 2018 2017 2018 2017 Basic earnings per common share: Net income $ 355 $ 272 $ 681 $ 480 Preferred stock dividends (21 ) (19 ) (33 ) (38 ) Net income available to common shareholders $ 334 $ 253 $ 648 $ 442 Average common shares issued and outstanding (000) 1,103,337 1,088,934 1,093,587 1,087,654 Basic earnings per common share $ 0.30 $ 0.23 $ 0.59 $ 0.41 Diluted earnings per common share: Net income available to common shareholders $ 334 $ 253 $ 648 $ 442 Effect of assumed preferred stock conversion — — — — Net income applicable to diluted earnings per share $ 334 $ 253 $ 648 $ 442 Average common shares issued and outstanding (000) 1,103,337 1,088,934 1,093,587 1,087,654 Dilutive potential common shares: Stock options and restricted stock units and awards 15,803 16,329 17,830 17,734 Shares held in deferred compensation plans 3,472 3,108 3,350 3,030 Dilutive impact of Preferred Stock — — 8,879 — Other — 156 — 154 Dilutive potential common shares 19,275 19,593 30,059 20,918 Total diluted average common shares issued and outstanding (000) 1,122,612 1,108,527 1,123,646 1,108,572 Diluted earnings per common share $ 0.30 $ 0.23 $ 0.58 $ 0.40

NON-INTEREST INCOME (Tables)

NON-INTEREST INCOME (Tables)	6 Months Ended
NON-INTEREST INCOME (Tables)	Jun. 30, 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 June 30, 2018 Six Months Ended June 30, 2018 Noninterest income Noninterest income from contracts with customers $ 217 $ 431 Noninterest income within the scope of other GAAP topics 119 219 Total noninterest income $ 336 $ 650 The following table illustrates the disaggregation by operating segment and major revenue stream and reconciles disaggregated revenue to segment revenue presented in Note 18 . Three Months Ended June 30, 2018 (dollar amounts in millions) Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated Major Revenue Streams Service charges on deposit accounts $ 72 $ 16 $ 2 $ 1 $ — $ 91 Cards and payment processing income 49 3 — — — 52 Trust and investment management services 5 2 — 35 — 42 Insurance income 10 1 — 10 — 21 Other income 10 1 — — — 11 Net revenue from contracts with customers $ 146 $ 23 $ 2 $ 46 $ — $ 217 Noninterest income within the scope of other GAAP topics 41 57 — 2 19 119 Total noninterest income $ 187 $ 80 $ 2 $ 48 $ 19 $ 336 Six Months Ended June 30, 2018 (dollar amounts in millions) Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated Major Revenue Streams Service charges on deposit accounts $ 140 $ 32 $ 3 $ 2 $ — $ 177 Cards and payment processing income 96 5 — — — 101 Trust and investment management services 12 2 — 72 — 86 Insurance income 18 2 — 21 1 42 Other Income 20 1 1 2 1 25 Net revenue from contracts with customers $ 286 $ 42 $ 4 $ 97 $ 2 $ 431 Noninterest income within the scope of other GAAP topics 75 107 2 1 34 219 Total noninterest income $ 361 $ 149 $ 6 $ 98 $ 36 $ 650

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	6 Months Ended
BENEFIT PLANS (Tables)	Jun. 30, 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 June 30, Three Months Ended June 30, (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 2 3 — — Net periodic (benefit) cost $ — $ (1 ) $ — $ (1 ) Pension Benefits (1) Post-Retirement Benefits (1) Six Months Ended June 30, Six Months Ended June 30, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ 2 $ 1 $ — $ — Interest cost 14 15 — — Expected return on plan assets (24 ) (28 ) — — Amortization of prior service cost — — (1 ) (1 ) Amortization of (gain) loss 4 4 — — Settlements 4 5 — — Net periodic (benefit) cost $ — $ (3 ) $ (1 ) $ (1 ) (1) The Pension and post-retirement (benefits) costs for 2018 and 2017 are recorded in Other noninterest income and Noninterest expense - personnel costs, respectively on the Condensed Consolidated Statements of Income.
Schedule of Costs of Retirement Plans	Huntington's expense related to the defined contribution plans during the second quarter 2018 and 2017 was $17 million and $11 million , respectively. For the six-month period ended June 30, 2018 and 2017, expense related to the defined contribution plans was $28 million and $22 million , respectively.

FAIR VALUES OF ASSETS AND LIA38

FAIR VALUES OF ASSETS AND LIABILITIES (Tables)	6 Months Ended
FAIR VALUES OF ASSETS AND LIABILITIES (Tables)	Jun. 30, 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 June 30, 2018 and December 31, 2017 are summarized below: Fair Value Measurements at Reporting Date Using Netting Adjustments (1) June 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Municipal securities $ — $ 5 $ — $ — $ 5 Other securities 78 2 — — 80 78 7 — — 85 Available-for-sale securities: U.S. Treasury securities 6 — — — 6 Residential CMOs — 7,250 — — 7,250 Residential MBS — 659 — — 659 Commercial MBS — 1,743 — — 1,743 Other agencies — 183 — — 183 Municipal securities — 587 3,178 — 3,765 Asset-backed securities — 373 — — 373 Corporate debt — 87 — — 87 Other securities/sovereign debt — 4 — — 4 6 10,886 3,178 — 14,070 Other securities 21 — — — 21 Loans held for sale — 643 — — 643 Loans held for investment — 50 34 — 84 MSRs — — 11 — 11 Derivative assets — 446 8 (275 ) 179 Liabilities Derivative liabilities — 399 7 (204 ) 202 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 Loans held for investment Opening balance $ 12 $ — $ 3,230 $ 37 Transfers into Level 3 — — — — Transfers out of Level 3 (1) — (9 ) — — Total gains/losses for the period: Included in earnings (1 ) 10 (1 ) — Included in OCI — — (9 ) — Purchases/originations — — 86 — Sales — — — — Repayments — — — (3 ) Settlements — — (128 ) — Closing balance $ 11 $ 1 $ 3,178 $ 34 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (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 Opening balance $ 13 $ 3 $ 2,868 $ 59 $ 44 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — (2 ) — — — Total gains/losses for the period: Included in earnings — 2 (1 ) (3 ) 2 Included in OCI — — 12 6 — Purchases/originations — — 115 — — Sales — — — (19 ) — Repayments — — — — (2 ) Settlements — — (122 ) — — Closing balance $ 13 $ 3 $ 2,872 $ 43 $ 44 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ 3 $ 12 $ 6 $ — (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. 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) — (14 ) — — — Total gains/losses for the period: Included in earnings — 16 (2 ) (2 ) — Included in OCI — — (37 ) 11 — Purchases/originations — — 279 — — Sales — — — (33 ) — Repayments — — — — (4 ) Settlements — — (229 ) — — Closing balance $ 11 $ 1 $ 3,178 $ — $ 34 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ 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 Opening balance $ 14 $ (2 ) $ 2,798 $ 76 $ 48 Transfers into Level 3 — — — — — Transfers out of Level 3 (1) — (3 ) — — — Total gains/losses for the period: Included in earnings (1 ) 8 (3 ) (3 ) 1 Included in OCI — — 33 9 — Purchases/originations — — 248 — — Sales — — — (38 ) — Repayments — — — — (5 ) Settlements — — (204 ) (1 ) — Closing balance $ 13 $ 3 $ 2,872 $ 43 $ 44 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (1 ) $ 8 $ 33 $ 9 $ —
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 and six-month periods ended June 30, 2018 and 2017 : Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ (1 ) $ 10 $ — $ — Securities gains (losses) — — — — Other expense — — (1 ) — Total $ (1 ) $ 10 $ (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 Classification of gains and losses in earnings: Mortgage banking income $ — $ 2 $ — $ — $ — Securities gains (losses) — — (1 ) (3 ) — Noninterest income — — — — 2 Total $ — $ 2 $ (1 ) $ (3 ) $ 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 $ — $ 16 $ — $ — $ — Securities gains (losses) — — — (2 ) — Other expense — — (2 ) — — Total $ — $ 16 $ (2 ) $ (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 ) $ 8 $ — $ — $ — Securities gains (losses) — — (3 ) (3 ) — Noninterest income — — — — 1 Total $ (1 ) $ 8 $ (3 ) $ (3 ) $ 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: June 30, 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 $ 643 $ 625 $ 18 $ — $ — $ — Loans held for investment 84 93 (9 ) 7 8 (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 and six-month periods ended June 30, 2018 and 2017 . Net gains (losses) from fair value changes Net gains (losses) from fair value changes (dollar amounts in millions) Three Months Ended June 30, Six Months Ended June 30, Assets 2018 2017 2018 2017 Loans held for sale $ 5 $ 5 $ 3 $ 14 Loans held for investment — 2 — 1
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 55 — — 55 — Other real estate owned 28 — — 28 (1 )
Quantitative information about significant unobservable level 3 fair value measurement inputs	Quantitative Information about Level 3 Fair Value Measurements at June 30, 2018 (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 6% - 44% (8%) Spread over forward interest rate 5% - 11% (8%) Derivative assets 8 Consensus Pricing Net market price -5% - 8% (2%) Estimated Pull through % 2% - 100% (90%) Derivative liabilities 7 Discounted cash flow Estimated conversion factor 163 % Estimated growth rate of Visa Class A shares 7 % Discount rate 3 % Timing of the resolution of the litigation 06/30/2020 Municipal securities 3,178 Discounted cash flow Discount rate 0% - 9% (4%) Cumulative default 0% - 64% (4%) Loss given default 5% - 90% (25%) Loans held for investment 34 Discounted cash flow Discount rate 7% - 19% (8%) Constant prepayment rate 2% - 22% (9%) Measured at fair value on a nonrecurring basis: Impaired loans 55 Appraisal value NA NA Other real estate owned 28 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 June 30, 2018 and December 31, 2017 : June 30, 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 1,423 — — 1,423 1,423 Trading account securities — — 85 85 85 Available-for-sale securities — — 14,070 14,070 14,070 Held-to-maturity securities 8,682 — — 8,682 8,391 Other securities 576 — 21 597 597 Loans held for sale — 66 643 709 713 Net loans and direct financing leases (1) 71,581 — 84 71,665 70,996 Derivatives — — 179 179 179 Financial Liabilities Deposits 79,587 — — 79,587 79,534 Short-term borrowings 2,442 — — 2,442 2,442 Long-term debt 9,726 — — 9,726 9,889 Derivatives — — 202 202 202 (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 June 30, 2018 and December 31, 2017 : Estimated Fair Value Measurements at Reporting Date Using June 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 78 $ 7 $ — $ 85 Available-for-sale securities 6 10,886 3,178 14,070 Held-to-maturity securities — 8,391 — 8,391 Other securities 21 — — 21 Loans held for sale — 643 70 713 Net loans and direct financing leases — 50 70,946 70,996 Financial Liabilities Deposits — 73,371 6,163 79,534 Short-term borrowings 2 — 2,440 2,442 Long-term debt — 9,416 473 9,889 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 INSTRUME39

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	6 Months Ended
DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset and liability derivatives included in accrued income and other assets	June 30, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Derivatives designated as Hedging Instruments Interest rate contracts $ 16 $ 66 $ 22 $ 121 Derivatives not designated as Hedging Instruments Interest rate contracts 268 176 187 100 Foreign exchange contracts 32 29 18 18 Commodities contracts 134 129 92 87 Equity contracts 4 6 3 5 Total Contracts $ 454 $ 406 $ 322 $ 331
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-month and six-month periods ended June 30, 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 June 30, 2018 Six Months Ended June 30, 2018 Interest rate contracts: Customer Capital markets fees $ 12 $ 19 Mortgage Banking Mortgage banking income — (8 ) Foreign exchange contracts Capital markets fees 7 12 Commodities contracts Capital markets fees — 2 Equity contracts Other noninterest expense (3 ) (3 ) Total $ 16 $ 22
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 June 30, 2018 and December 31, 2017 , identified by the underlying interest rate-sensitive instruments. June 30, 2018 (dollar amounts in millions) Fair Value Hedges Cash Flow Hedges Total Instruments associated with: Investment securities — 12 $ 12 Subordinated notes 375 — 375 Long-term debt 4,990 — 4,990 Total notional value at June 30, 2018 $ 5,365 $ 12 $ 5,377 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 June 30, 2018 and December 31, 2017 . June 30, 2018 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Asset conversion swaps Receive fixed—generic $ 12 1.7 $ — 2.20 % 2.07 % Liability conversion swaps Receive fixed—generic 5,365 2.2 (50 ) 1.93 2.27 Total swap portfolio at June 30, 2018 $ 5,377 2.2 $ (50 ) 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 )
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 and six-month periods ended June 30, 2018 and 2017 . Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Interest rate contracts Change in fair value of interest rate swaps hedging subordinated notes (1) 41 2 24 (2 ) Change in fair value of hedged subordinated notes (1) (42 ) (2 ) (24 ) 3 Change in fair value of interest rate swaps hedging other long-term debt (1) 93 16 42 6 Change in fair value of hedged other long-term debt (1) (90 ) (17 ) (37 ) (8 ) (1) Recognized in Interest expense—subordinated notes and other long-term debt in the Unaudited Condensed Consolidated Statements of Income.
Amounts recorded on the balance sheet related to cumulative basis adjustments	As of June 30, 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) June 30, 2018 June 30, 2018 Long-term debt $ 5,302 $ (55 ) The cumulative amount of fair value hedging adjustments remaining for any hedged assets and liabilities for which hedge accounting has been discontinued is $144 million at June 30, 2018 .
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 June 30, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Interest rate lock agreements $ 8 $ — $ 6 $ — Forward trades and options — 5 1 — Total derivatives used in mortgage banking activities $ 8 $ 5 $ 7 $ —
Summary of MSR hedging activity	MSR hedging activity (dollar amounts in millions) June 30, 2018 December 31, 2017 Notional Value $ — $ 188 Trading Liabilities — 3 Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Trading gains (losses) — 2 (8 ) 1
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 June 30, 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 June 30, 2018 Derivatives $ 454 $ (275 ) $ 179 $ — $ (61 ) $ 118 December 31, 2017 Derivatives 322 (190 ) 132 (11 ) (18 ) 103
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 June 30, 2018 Derivatives $ 406 $ (204 ) $ 202 $ — $ (20 ) $ 182 December 31, 2017 Derivatives 331 (245 ) 86 — (21 ) 65

VIEs (Tables)

VIEs (Tables)	6 Months Ended
VIEs (Tables)	Jun. 30, 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 June 30, 2018 , and December 31, 2017 : June 30, 2018 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 4 $ 1 $ 4 2015-1 Automobile Trust — — — Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 625 293 625 Other Investments 135 62 135 Total $ 778 $ 608 $ 764 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 June 30, 2018 follows: (dollar amounts in millions) Rate Principal amount of subordinated note/ debenture issued to trust (1) Investment in unconsolidated subsidiary Huntington Capital I 3.04 % (2) $ 70 $ 6 Huntington Capital II 2.96 (3) 32 3 Sky Financial Capital Trust III 3.74 (4) 72 2 Sky Financial Capital Trust IV 3.74 (4) 74 2 Camco Financial Trust 3.67 (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 June 30, 2018 , based on three-month LIBOR + 0.70% . (3) Variable effective rate at June 30, 2018 , based on three-month LIBOR + 0.625% . (4) Variable effective rate at June 30, 2018 , based on three-month LIBOR + 1.40% . (5) Variable effective rate at June 30, 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 June 30, 2018 and December 31, 2017 . (dollar amounts in millions) June 30, December 31, Affordable housing tax credit investments $ 1,024 $ 996 Less: amortization (399 ) (360 ) Net affordable housing tax credit investments $ 625 $ 636 Unfunded commitments $ 293 $ 335 The following table presents other information relating to Huntington’s affordable housing tax credit investments for the three-month and six-month periods ended June 30, 2018 and 2017 . Three Months Ended Six Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Tax credits and other tax benefits recognized $ 23 $ 23 $ 46 $ 46 Proportional amortization method Tax credit amortization expense included in provision for income taxes 20 17 39 34

COMMITMENTS AND CONTINGENT LI41

COMMITMENTS AND CONTINGENT LIABILITIES (Tables)	6 Months Ended
COMMITMENTS AND CONTINGENT LIABILITIES (Tables)	Jun. 30, 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 June 30, 2018 and December 31, 2017 , were as follows: (dollar amounts in millions) June 30, December 31, Contract amount representing credit risk Commitments to extend credit: Commercial $ 16,641 $ 16,219 Consumer 14,338 13,384 Commercial real estate 1,200 1,366 Standby letters of credit 601 510 Commercial letters-of-credit 27 21

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	6 Months Ended
SEGMENT REPORTING (Tables)	Jun. 30, 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 June 30, 2018 , December 31, 2017 , and June 30, 2017 , reported results by business segment. Three Months Ended June 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 413 $ 229 $ 100 $ 46 $ (4 ) $ 784 Provision (benefit) for credit losses 27 18 10 1 — 56 Noninterest income 187 80 2 48 19 336 Noninterest expense 429 128 38 66 (9 ) 652 Provision (benefit) for income taxes 30 35 11 6 (25 ) 57 Net income (loss) $ 114 $ 128 $ 43 $ 21 $ 49 $ 355 2017 Net interest income 385 223 106 42 (11 ) 745 Provision (benefit) for credit losses 17 (5 ) 16 (3 ) — 25 Noninterest income 184 69 3 47 22 325 Noninterest expense 413 119 38 61 63 694 Provision (benefit) for income taxes 49 62 19 11 (62 ) 79 Net income (loss) $ 90 $ 116 $ 36 $ 20 $ 10 $ 272 Six Months Ended June 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 808 $ 449 $ 199 $ 91 $ 7 $ 1,554 Provision (benefit) for credit losses 59 39 23 1 — 122 Noninterest income 361 149 6 98 36 650 Noninterest expense 840 249 74 123 (1 ) 1,285 Provision (benefit) for income taxes 57 65 23 13 (42 ) 116 Net income (loss) $ 213 $ 245 $ 85 $ 52 $ 86 $ 681 2017 Net interest income $ 759 $ 452 $ 210 $ 83 $ (29 ) $ 1,475 Provision (benefit) for credit losses 51 16 26 — — 93 Noninterest income 355 134 8 94 47 638 Noninterest expense 826 236 74 124 142 1,402 Provision (benefit) for income taxes 83 117 41 19 (122 ) 138 Net income (loss) $ 154 $ 217 $ 77 $ 34 $ (2 ) $ 480 Assets at Deposits at (dollar amounts in millions) June 30, December 31, June 30, December 31, Consumer & Business Banking $ 27,013 $ 26,220 $ 48,186 $ 45,643 Commercial Banking 33,036 32,118 21,142 21,235 Vehicle Finance 18,590 17,865 340 358 RBHPCG 6,185 5,821 5,985 6,057 Treasury / Other 20,534 22,161 3,934 3,748 Total $ 105,358 $ 104,185 $ 79,587 $ 77,041
Segment Disclosure of Assets and Deposits	Assets at Deposits at (dollar amounts in millions) June 30, December 31, June 30, December 31, Consumer & Business Banking $ 27,013 $ 26,220 $ 48,186 $ 45,643 Commercial Banking 33,036 32,118 21,142 21,235 Vehicle Finance 18,590 17,865 340 358 RBHPCG 6,185 5,821 5,985 6,057 Treasury / Other 20,534 22,161 3,934 3,748 Total $ 105,358 $ 104,185 $ 79,587 $ 77,041

LOANS _ LEASES AND ALLOWANCE 43

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	3 Months Ended
	Jun. 30, 2018USD ($)reserve	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases receivable net premium	$ 372,000,000		$ 334,000,000
Consumer loans	84,000,000		93,000,000
Allowance for loan and lease losses	$ (741,000,000)	$ (721,000,000)	(691,000,000)	$ (668,000,000)	$ (673,000,000)	$ (638,000,000)
Number of days past due	30 days
Allowance number of reserves \| reserve	2
Collateral for secured borrowings	$ 34,100,000,000		31,700,000,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan and lease losses	$ (531,000,000)	(515,000,000)	(482,000,000)	(475,000,000)	(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	$ (210,000,000)	$ (206,000,000)	(209,000,000)	$ (193,000,000)	$ (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	$ 0		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	81,000,000		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 44

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Loan and Lease Portfolio Composition (Details) - USD ($) $ in Thousands		Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial		$ 28,850,000		$ 28,107,000
Commercial real estate		7,201,000		7,225,000
Automobile		12,390,000		12,100,000
Home equity		9,907,000		10,099,000
Residential mortgage		10,006,000		9,026,000
Recreation Finance		2,846,000		2,438,000
Other consumer		1,206,000		1,122,000
Loans and leases	[1]	72,406,000		70,117,000
Allowance for loan and lease losses		(741,000)	$ (721,000)	(691,000)	$ (668,000)	$ (673,000)	$ (638,000)
Net loans and leases		71,665,000		69,426,000
Loans Receivable, Fair Value Disclosure		84,000		93,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile		12,390,000		12,099,000
Home equity		9,905,000		10,097,000
Residential mortgage		9,925,000		8,937,000
Other consumer		1,206,000		1,122,000
Allowance for loan and lease losses		(210,000)	(206,000)	(209,000)	(193,000)	(193,000)	(187,000)
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		12,390,000		12,100,000
Loans Receivable, Fair Value Disclosure		0		1,000
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		9,907,000		10,099,000
Loans Receivable, Fair Value Disclosure		2,000		2,000
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		10,006,000		9,026,000
Loans Receivable, Fair Value Disclosure		81,000		89,000
Consumer \| RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		2,846,000		2,438,000
Loans Receivable, Fair Value Disclosure		1,000		1,000
Consumer \| Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,206,000		1,122,000
Loans Receivable, Fair Value Disclosure		0		0
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial		28,850,000		28,107,000
Commercial real estate		7,201,000		7,225,000
Allowance for loan and lease losses		(531,000)	$ (515,000)	(482,000)	$ (475,000)	$ (480,000)	$ (451,000)
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		28,850,000		28,107,000
Loans Receivable, Fair Value Disclosure		0		0
Commercial \| Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		7,201,000		7,225,000
Loans Receivable, Fair Value Disclosure		$ 0		$ 0

[1]	Amounts represent loans for which Huntington has elected the fair value option.

LOANS _ LEASES AND ALLOWANCE 45

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Certain Loans Acquired Ending and Unpaid Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance			$ 41,000
Total ALLL balance	$ 741,000	$ 721,000	691,000	$ 668,000	$ 673,000	$ 638,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ALLL balance	$ 531,000	$ 515,000	482,000	$ 475,000	$ 480,000	$ 451,000
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Ending Balance			$ 39,000

LOANS _ LEASES AND ALLOWANCE 46

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Nonaccrual Loans by Loan Class (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 378	$ 349
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	207	161
Commercial \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	25	29
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	4	6
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	68	68
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	73	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 47

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - NALs Past Due (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		$ 687	$ 714
Current		71,635	69,269
Purchased Credit Impaired			41
Consumer loans		84	93
Loans and leases	[1]	72,406	70,117
90 or more days past due and accruing		132	115
30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		292	335
60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		122	108
90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		273	271
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		138	114
Current		28,712	27,954
Purchased Credit Impaired			39
Consumer loans		0	0
Loans and leases		28,850	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 (1)		47	35
Commercial \| Commercial and Industrial \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		28	14
Commercial \| Commercial and Industrial \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		63	65
Commercial \| Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		20	22
Current		7,181	7,201
Purchased Credit Impaired			2
Consumer loans		0	0
Loans and leases		7,201	7,225
90 or more days past due and accruing		0	3
Commercial \| Real Estate \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		2	10
Commercial \| Real Estate \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		12	1
Commercial \| Real Estate \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		6	11
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		93	117
Current		12,297	11,982
Purchased Credit Impaired			0
Consumer loans		0	1
Loans and leases		12,390	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 (1)		71	89
Consumer \| Automobile \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		15	18
Consumer \| Automobile \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		7	10
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		122	128
Current		9,783	9,969
Purchased Credit Impaired			0
Consumer loans		2	2
Loans and leases		9,907	10,099
90 or more days past due and accruing		16	18
Consumer \| Home Equity \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		44	49
Consumer \| Home Equity \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		19	19
Consumer \| Home Equity \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		59	60
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		281	295
Current		9,644	8,642
Purchased Credit Impaired			0
Consumer loans		81	89
Loans and leases		10,006	9,026
90 or more days past due and accruing		96	72
Consumer \| Residential Mortgage \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		108	129
Consumer \| Residential Mortgage \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		40	48
Consumer \| Residential Mortgage \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		133	118
Consumer \| RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		11	16
Current		2,834	2,421
Purchased Credit Impaired			0
Consumer loans		1	1
Loans and leases		2,846	2,438
90 or more days past due and accruing		1	1
Consumer \| RV and Marine FInance \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		8	11
Consumer \| RV and Marine FInance \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		2	3
Consumer \| RV and Marine FInance \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		1	2
Consumer \| Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		22	22
Current		1,184	1,100
Purchased Credit Impaired			0
Consumer loans		0	0
Loans and leases		1,206	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 (1)		12	12
Consumer \| Other Consumer \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		6	5
Consumer \| Other Consumer \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		$ 4	$ 5

[1]	Amounts represent loans for which Huntington has elected the fair value option.

LOANS _ LEASES AND ALLOWANCE 48

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision For (Reduction In Allowance) Unfunded Loan Commitments and Letters of Credit.	$ 8,000	$ (7,000)	$ 6,000	$ (13,000)
Portion of ALLL balance:
ALLL balance, beginning of period	721,000	673,000	691,000	638,000
Loan charge-offs	(53,000)	(57,000)	(126,000)	(127,000)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	25,000	21,000	60,000	52,000
Provision for credit losses	56,000	25,000	122,000	93,000
Provision For (Reduction In Allowance) Loan and Lease Losses.	48,000	31,000	116,000	105,000
ALLL balance, end of period	741,000	668,000	741,000	668,000
AULC Balance, beginning of period	85,000	92,000	87,000	98,000
AULC Balance, end of period	93,000	85,000	93,000	85,000
ACL balance, end of period	834,000	753,000	834,000	753,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision For (Reduction In Allowance) Unfunded Loan Commitments and Letters of Credit.	8,000	(7,000)	6,000	(5,000)
Portion of ALLL balance:
ALLL balance, beginning of period	515,000	480,000	482,000	451,000
Loan charge-offs	(12,000)	(15,000)	(35,000)	(39,000)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	10,000	6,000	30,000	24,000
Provision for credit losses		4,000	54,000
Provision For (Reduction In Allowance) Loan and Lease Losses.	18,000			39,000
ALLL balance, end of period	531,000	475,000	531,000	475,000
AULC Balance, beginning of period	82,000	89,000	84,000	87,000
AULC Balance, end of period	90,000	82,000	90,000	82,000
ACL balance, end of period	621,000	557,000	621,000	557,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision For (Reduction In Allowance) Unfunded Loan Commitments and Letters of Credit.	0	0	0	(8,000)
Portion of ALLL balance:
ALLL balance, beginning of period	206,000	193,000	209,000	187,000
Loan charge-offs	(41,000)	(42,000)	(91,000)	(88,000)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	15,000	15,000	30,000	28,000
Provision for credit losses		27,000
Provision For (Reduction In Allowance) Loan and Lease Losses.	30,000		62,000	66,000
ALLL balance, end of period	210,000	193,000	210,000	193,000
AULC Balance, beginning of period	3,000	3,000	3,000	11,000
AULC Balance, end of period	3,000	3,000	3,000	3,000
ACL balance, end of period	$ 213,000	$ 196,000	$ 213,000	$ 196,000

LOANS _ LEASES AND ALLOWANCE 49

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Credit Quality Indicators (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	$ 28,850	$ 28,107
Commercial real estate	7,201	7,225
Automobile	12,390	12,100
Home equity	9,907	10,099
Residential mortgage	10,006	9,026
Other consumer	1,206	1,122
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	28,850	28,107
Commercial real estate	7,201	7,225
Commercial \| Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	26,940	26,268
Commercial real estate	6,895	6,909
Commercial \| Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	1,115	1,116
Commercial real estate	123	115
Commercial \| OLEM
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	784	694
Commercial real estate	181	200
Commercial \| Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	11	29
Commercial real estate	2	1
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	12,390	12,099
Home equity	9,905	10,097
Residential mortgage	9,925	8,937
RV and marine finance	2,845	2,437
Other consumer	1,206	1,122
Consumer \| Greater than 750
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	6,338	6,102
Home equity	6,219	6,352
Residential mortgage	6,579	5,697
RV and marine finance	1,805	1,433
Other consumer	452	428
Consumer \| 650-749
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	4,469	4,312
Home equity	3,014	3,024
Residential mortgage	2,598	2,581
RV and marine finance	887	863
Other consumer	580	540
Consumer \| Less Than 650
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	1,296	1,390
Home equity	601	617
Residential mortgage	592	605
RV and marine finance	96	96
Other consumer	116	143
Consumer \| Other FICO score
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	287	295
Home equity	71	104
Residential mortgage	156	54
RV and marine finance	57	45
Other consumer	$ 58	$ 11

LOANS _ LEASES AND ALLOWANCE 50

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - ALLL Attributable to Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment	$ 692,000		$ 650,000
Attributable to loans individually evaluated for impairment	49,000		41,000
Total ALLL balance	741,000	$ 721,000	691,000	$ 668,000	$ 673,000	$ 638,000
Portion of loan and lease ending balance:
Collectively evaluated for impairment	71,081,000		68,760,000
Individually evaluated for impairment	1,241,000		1,223,000
Financing Receivable Evaluated For Impairment	72,322,000		70,024,000
Commercial
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment	492,000		450,000
Attributable to loans individually evaluated for impairment	39,000		32,000
Total ALLL balance	531,000	515,000	482,000	475,000	480,000	451,000
Portion of loan and lease ending balance:
Collectively evaluated for impairment	35,409,000		34,684,000
Individually evaluated for impairment	642,000		607,000
Financing Receivable Evaluated For Impairment	36,051,000		35,332,000
Consumer
Portion of ALLL balance:
Attributable to loans collectively evaluated for impairment	200,000		200,000
Attributable to loans individually evaluated for impairment	10,000		9,000
Total ALLL balance	210,000	$ 206,000	209,000	$ 193,000	$ 193,000	$ 187,000
Portion of loan and lease ending balance:
Collectively evaluated for impairment	35,672,000		34,076,000
Individually evaluated for impairment	599,000		616,000
Financing Receivable Evaluated For Impairment	$ 36,271,000		34,692,000
Purchased credit-impaired
Portion of loan and lease ending balance:
Collectively evaluated for impairment			41,000
Purchased credit-impaired \| Commercial
Portion of loan and lease ending balance:
Collectively evaluated for impairment			41,000
Purchased credit-impaired \| Consumer
Portion of loan and lease ending balance:
Collectively evaluated for impairment			$ 0

LOANS _ LEASES AND ALLOWANCE 51

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	$ 0		$ 0		$ 0
Average balance of impaired loans with no allowance recorded	0	$ 0	0	$ 0
Interest income recognized on impaired loans with no allowance recorded	0	0	0	0
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	0		0		0
Average balance of impaired loans with no allowance recorded	0	0	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0	0	0
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid principal balance of impaired loans with no allowance recorded	0		0		0
Average balance of impaired loans with no allowance recorded	0	0	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0	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		0
Average balance of impaired loans with no allowance recorded	0		0
Interest income recognized on impaired loans with no allowance recorded	0		0
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	276,000		276,000		284,000
Unpaid principal balance of impaired loans with no allowance recorded	305,000		305,000		311,000
Average balance of impaired loans with no allowance recorded	259,000	263,000	268,000	268,000
Interest income recognized on impaired loans with no allowance recorded	6,000	5,000	10,000	9,000
Ending balance of impaired loans with allowance recorded	277,000		277,000		257,000
Unpaid principal balance of impaired loans with allowance recorded	311,000		311,000		280,000
Related Allowance	37,000		37,000		29,000
Impaired Financing Receivable, Average Recorded Investment	554,000	521,000	551,000	579,000
Impaired Financing Receivable, Interest Income, Accrual Method	9,000	7,000	16,000	13,000
Average balance of impaired loans with allowance recorded	295,000	258,000	283,000	311,000
Interest income recognized on impaired loans with allowance recorded	3,000	2,000	6,000	4,000
Loans considered impaired due to status as a TDR	401,000		401,000		382,000
Impaired Financing Receivable, Recorded Investment	553,000		553,000		541,000
Impaired Financing Receivable, Unpaid Principal Balance	616,000		616,000		591,000
Commercial \| Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	39,000		39,000		56,000
Unpaid principal balance of impaired loans with no allowance recorded	58,000		58,000		81,000
Average balance of impaired loans with no allowance recorded		82,000		85,000
Interest income recognized on impaired loans with no allowance recorded		2,000		4,000
Ending balance of impaired loans with allowance recorded	50,000		50,000
Unpaid principal balance of impaired loans with allowance recorded	56,000		56,000
Related Allowance	2,000		2,000
Loans considered impaired due to status as a TDR	79,000		79,000		93,000
Impaired Financing Receivable, Recorded Investment	89,000		89,000
Impaired Financing Receivable, Unpaid Principal Balance	114,000		114,000
Commercial \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average balance of impaired loans with no allowance recorded	55,000		55,000
Interest income recognized on impaired loans with no allowance recorded	2,000		4,000
Ending balance of impaired loans with allowance recorded					51,000
Unpaid principal balance of impaired loans with allowance recorded					51,000
Related Allowance					3,000
Impaired Financing Receivable, Average Recorded Investment	101,000	121,000	103,000	143,000
Impaired Financing Receivable, Interest Income, Accrual Method	2,000	2,000	5,000	5,000
Average balance of impaired loans with allowance recorded	46,000	39,000	48,000	58,000
Interest income recognized on impaired loans with allowance recorded	0	0	1,000	1,000
Impaired Financing Receivable, Recorded Investment					107,000
Impaired Financing Receivable, Unpaid Principal Balance					132,000
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0		0		0
Ending balance of impaired loans with allowance recorded	36,000		36,000		36,000
Unpaid principal balance of impaired loans with allowance recorded	40,000		40,000		40,000
Related Allowance	2,000		2,000		2,000
Impaired Financing Receivable, Average Recorded Investment	37,000	33,000	36,000	32,000
Impaired Financing Receivable, Interest Income, Accrual Method	1,000	1,000	1,000	1,000
Average balance of impaired loans with allowance recorded	37,000	33,000	36,000	32,000
Interest income recognized on impaired loans with allowance recorded	1,000	1,000	1,000	1,000
Impaired Financing Receivable, Recorded Investment	36,000		36,000		36,000
Impaired Financing Receivable, Unpaid Principal Balance	40,000		40,000		40,000
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0		0		0
Ending balance of impaired loans with allowance recorded	327,000		327,000		334,000
Unpaid principal balance of impaired loans with allowance recorded	372,000		372,000		385,000
Related Allowance	13,000		13,000		14,000
Impaired Financing Receivable, Average Recorded Investment	331,000	326,000	332,000	324,000
Impaired Financing Receivable, Interest Income, Accrual Method	4,000	4,000	7,000	8,000
Average balance of impaired loans with allowance recorded	331,000	326,000	332,000	324,000
Interest income recognized on impaired loans with allowance recorded	4,000	4,000	7,000	8,000
Impaired Financing Receivable, Recorded Investment	327,000		327,000		334,000
Impaired Financing Receivable, Unpaid Principal Balance	372,000		372,000		385,000
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0		0		0
Ending balance of impaired loans with allowance recorded	294,000		294,000		308,000
Unpaid principal balance of impaired loans with allowance recorded	327,000		327,000		338,000
Related Allowance	4,000		4,000		4,000
Impaired Financing Receivable, Average Recorded Investment	300,000	339,000	303,000	335,000
Impaired Financing Receivable, Interest Income, Accrual Method	3,000	3,000	5,000	6,000
Average balance of impaired loans with allowance recorded	300,000	339,000	303,000	335,000
Interest income recognized on impaired loans with allowance recorded	3,000	3,000	5,000	6,000
Impaired Financing Receivable, Recorded Investment	294,000		294,000		308,000
Impaired Financing Receivable, Unpaid Principal Balance	327,000		327,000		338,000
Consumer \| RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0		0		0
Unpaid principal balance of impaired loans with no allowance recorded					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	2,000		2,000		2,000
Unpaid principal balance of impaired loans with allowance recorded	2,000		2,000		3,000
Related Allowance	0		0		0
Impaired Financing Receivable, Average Recorded Investment	2,000	1,000	2,000	1,000
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Average balance of impaired loans with allowance recorded	2,000	1,000	2,000	1,000
Interest income recognized on impaired loans with allowance recorded	0	0	0	0
Impaired Financing Receivable, Recorded Investment	2,000		2,000		2,000
Impaired Financing Receivable, Unpaid Principal Balance	2,000		2,000		3,000
Consumer \| Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	0		0		0
Unpaid principal balance of impaired loans with no allowance recorded	0		0		0
Average balance of impaired loans with no allowance recorded	0	0	0	0
Interest income recognized on impaired loans with no allowance recorded	0	0	0	0
Ending balance of impaired loans with allowance recorded	9,000		9,000		8,000
Unpaid principal balance of impaired loans with allowance recorded	9,000		9,000		8,000
Related Allowance	3,000		3,000		2,000
Impaired Financing Receivable, Average Recorded Investment	7,000	4,000	7,000	4,000
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
Average balance of impaired loans with allowance recorded	7,000	4,000	7,000	4,000
Interest income recognized on impaired loans with allowance recorded	0	$ 0	0	$ 0
Impaired Financing Receivable, Recorded Investment	9,000		9,000		8,000
Impaired Financing Receivable, Unpaid Principal Balance	$ 9,000		$ 9,000		$ 8,000

LOANS _ LEASES AND ALLOWANCE 52

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - TDRs (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)contract	Jun. 30, 2017USD ($)contract	Jun. 30, 2018USD ($)contract	Jun. 30, 2017USD ($)contract
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	1,741	1,178	3,356	2,606
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 221,000,000	$ 0	$ 401,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 8,000,000	0	$ 9,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts	4	1	5	2
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Commercial \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract		228		464
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	$ 168,000,000	0	$ 281,000
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 7,000,000	$ 0	$ 8,000
Commercial \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	1	1	3	4
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0	$ 0	$ 0
Commercial \| Commercial and Industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	269	230	510	470
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 168,000,000	$ 0	$ 281,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 7,000,000	0	$ 8,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial and Industrial \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial and Industrial \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	264		502
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial and Industrial \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial Real Estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	38	19	86	43
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 25,000,000	$ 0	$ 56,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 1,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial Real Estate \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	0	0	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial Real Estate \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	36	19	84	43
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 25,000,000	$ 0	$ 56,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 1,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Commercial \| Commercial Real Estate \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	2	0	2	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Automobile
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	613	537	1,240	1,268
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 4,000,000	$ 0	$ 11,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Automobile \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	10	5	26	19
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Automobile \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	382	334	793	811
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 3,000,000	$ 0	$ 7,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Automobile \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	221	198	421	438
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000	$ 0	$ 4,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Automobile \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	0	0	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Home Equity
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	169	233	325	492
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 12,000,000	$ 0	$ 25,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Home Equity \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	0	9	1	17
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 1,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Home Equity \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	113	135	212	241
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 8,000,000	$ 0	$ 14,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 1,000,000	0	$ 1,000
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Home Equity \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	56	77	105	164
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 3,000,000	$ 0	$ 6,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ (1,000,000)	0	$ (1,000)
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Home Equity \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	0	12	7	70
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000	$ 0	$ 4,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Residential Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	119	111	202	252
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 11,000,000	$ 0	$ 27,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 1,000,000	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Residential Mortgage \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	4	0	4	2
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Residential Mortgage \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	107	81	179	180
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 8,000,000	$ 0	$ 19,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 1,000,000	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Residential Mortgage \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	7	25	17	49
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 2,000,000	$ 0	$ 5,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Residential Mortgage \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	1	5	2	21
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000	$ 0	$ 3,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| RV and Marine FInance
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	40	44	59	73
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000	$ 0	$ 1,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| RV and Marine FInance \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	0	0	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| RV and Marine FInance \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	14	10	17	24
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| RV and Marine FInance \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	26	34	42	49
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1,000,000	$ 0	$ 1,000
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| RV and Marine FInance \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
New Troubled Debt Restructuring, Number of Contracts \| contract	0	0	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	0	$ 0	0	$ 0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Other Consumer
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	493	4	934	8
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0	$ 0	$ 0
Consumer \| Other Consumer \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	491	0	931	1
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0	$ 0	$ 0
Consumer \| Other Consumer \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	1	2	1	4
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0	$ 0	$ 0
Consumer \| Other Consumer \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	1	2	2	3
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0	$ 0	$ 0
Consumer \| Other Consumer \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	0	0	0	0
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
New Troubled Debt Restructuring, Financial effects of modification	$ 0	$ 0	$ 0	$ 0
Consumer \| Other Consumer Loan [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Other Consumer Loan [Member] \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Other Consumer Loan [Member] \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Other Consumer Loan [Member] \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0
Consumer \| Other Consumer Loan [Member] \| Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Subsequent Default, Number of Contracts \| contract	0		0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0		$ 0

AVAILABLE-FOR-SALE SECURITIES -

AVAILABLE-FOR-SALE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Pledged investment securities to secure public and trust deposits, trading account liabilities, US Treasury demand notes and security repurchase agreements	$ 5,000		$ 5,000	$ 6,000
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	$ 6

AVAILABLE-FOR-SALE SECURITIES54

AVAILABLE-FOR-SALE SECURITIES - Contractual Maturities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	$ 6,805	$ 5,545
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	170	61
Over 12 Months	6,368	6,728
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	312	225
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	13,173	12,273
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(482)	(286)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost	14,539	15,127
Unrealized Gross Gains	13	28
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(482)	(286)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale securities	14,070	14,869
U.S. Treasury
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	6	5
Amortized Cost	6	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	6	5
Available-for-sale securities	6	5
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	3,217	1,660
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	86	19
Over 12 Months	3,988	4,520
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	218	159
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	7,205
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(304)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, 1-5 years	0	1
Amortized Cost, 6-10 years	44	90
Amortized Cost, Over 10 years	7,510	6,570
Amortized Cost	7,554	6,661
Unrealized Gross Gains	0	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(304)	(178)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	0	1
Fair Value, 6-10 years	42	89
Fair Value, Over 10 years	7,208	6,394
Available-for-sale securities	7,250	6,484
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	638	1,078
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	19	5
Over 12 Months	12	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	650	1,089
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(19)	(5)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, 1-5 years	4	6
Amortized Cost, 6-10 years	31	7
Amortized Cost, Over 10 years	643	1,358
Amortized Cost	678	1,371
Unrealized Gross Gains	0	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(19)	(5)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	4	6
Fair Value, 6-10 years	30	8
Fair Value, Over 10 years	625	1,353
Available-for-sale securities	659	1,367
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	285	960
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	9	15
Over 12 Months	1,458	1,527
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	63	37
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,743	2,487
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(72)	(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	1,737	2,365
Amortized Cost	1,815	2,539
Unrealized Gross Gains	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(72)	(52)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	66	22
Fair Value, 6-10 years	8	148
Fair Value, Over 10 years	1,669	2,317
Available-for-sale securities	1,743	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	88	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	0
Over 12 Months	85	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	173	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(5)	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	179	58
Amortized Cost	188	69
Unrealized Gross Gains	0	1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(5)	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	174	59
Available-for-sale securities	183	70
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	4,228	3,737
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	116	39
Over 12 Months	5,543	6,058
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	284	196
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	9,771	9,795
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(400)	(235)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost	10,241	10,645
Unrealized Gross Gains	0	3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(400)	(235)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale securities	9,841	10,413
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	2,306	1,681
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	49	21
Over 12 Months	723	497
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	24	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,029	2,178
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(73)	(35)
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Amortized Cost, Under 1 year	164	103
Amortized Cost, 1-5 years	1,115	1,140
Amortized Cost, 6-10 years	1,702	1,709
Amortized Cost, Over 10 years	845	940
Amortized Cost	3,826	3,892
Unrealized Gross Gains	12	21
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(73)	(35)
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	164	103
Fair Value, 1-5 years	1,105	1,134
Fair Value, 6-10 years	1,674	1,704
Fair Value, Over 10 years	822	937
Available-for-sale securities	3,765	3,878
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	210	127
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4	1
Over 12 Months	102	173
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	4	15
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	312	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	40	80
Amortized Cost, 6-10 years	46	53
Amortized Cost, Over 10 years	295	349
Amortized Cost	381	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	39	80
Fair Value, 6-10 years	46	54
Fair Value, Over 10 years	288	333
Available-for-sale securities	373	467
Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Less than 12 Months	61
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1
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	61
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(1)
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	75	73
Amortized Cost, 6-10 years	11	20
Amortized Cost, Over 10 years	0	13
Amortized Cost	87	106
Unrealized Gross Gains	1	3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(1)	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	74	74
Fair Value, 6-10 years	12	21
Fair Value, Over 10 years	0	14
Available-for-sale securities	87	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	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	0
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	0	1
Amortized Cost, 1-5 years	4	1
Amortized Cost	4	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	0	1
Fair Value, 1-5 years	4	1
Available-for-sale securities	$ 4	$ 2

AVAILABLE-FOR-SALE SECURITIES55

AVAILABLE-FOR-SALE SECURITIES - Schedule of Amortized Cost, Fair Value, and Gross Unrealized Gains and Losses (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 14,539	$ 15,127
Unrealized Gross Gains	13	28
Unrealized Gross Losses	(482)	(286)
Fair Value	14,070	14,869
U.S. Treasury
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6	5
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	6	5
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	7,554	6,661
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(304)	(178)
Fair Value	7,250	6,484
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	678	1,371
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(19)	(5)
Fair Value	659	1,367
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,815	2,539
Unrealized Gross Gains	0	0
Unrealized Gross Losses	(72)	(52)
Fair Value	1,743	2,487
Federal agencies, Other agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	188	69
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(5)	0
Fair Value	183	70
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,241	10,645
Unrealized Gross Gains	0	3
Unrealized Gross Losses	(400)	(235)
Fair Value	9,841	10,413
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,826	3,892
Unrealized Gross Gains	12	21
Unrealized Gross Losses	(73)	(35)
Fair Value	3,765	3,878
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	381	482
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(8)	(16)
Fair Value	373	467
Corporate debt
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	87	106
Unrealized Gross Gains	1	3
Unrealized Gross Losses	(1)	0
Fair Value	87	109
Other securities/Sovereign debt
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4	2
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	$ 4	$ 2

AVAILABLE-FOR-SALE SECURITIES A

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value
Less than 12 Months	$ 6,805	$ 5,545
Over 12 Months	6,368	6,728
Total	13,173	12,273
Gross Unrealized Losses
Less than 12 Months	(170)	(61)
Over 12 Months	(312)	(225)
Total	(482)	(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	3,217	1,660
Over 12 Months	3,988	4,520
Total	7,205
Gross Unrealized Losses
Less than 12 Months	(86)	(19)
Over 12 Months	(218)	(159)
Total	(304)
Residential Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	638	1,078
Over 12 Months	12	11
Total	650	1,089
Gross Unrealized Losses
Less than 12 Months	(19)	(5)
Over 12 Months	0	0
Total	(19)	(5)
Commercial Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	285	960
Over 12 Months	1,458	1,527
Total	1,743	2,487
Gross Unrealized Losses
Less than 12 Months	(9)	(15)
Over 12 Months	(63)	(37)
Total	(72)	(52)
Federal agencies, Other agencies
Fair Value
Less than 12 Months	88	39
Over 12 Months	85	0
Total	173	39
Gross Unrealized Losses
Less than 12 Months	(2)	0
Over 12 Months	(3)	0
Total	(5)	0
Total U.S. Treasury, Federal agency and other agency securities
Fair Value
Less than 12 Months	4,228	3,737
Over 12 Months	5,543	6,058
Total	9,771	9,795
Gross Unrealized Losses
Less than 12 Months	(116)	(39)
Over 12 Months	(284)	(196)
Total	(400)	(235)
Municipal securities
Fair Value
Less than 12 Months	2,306	1,681
Over 12 Months	723	497
Total	3,029	2,178
Gross Unrealized Losses
Less than 12 Months	(49)	(21)
Over 12 Months	(24)	(14)
Total	(73)	(35)
Asset-backed securities
Fair Value
Less than 12 Months	210	127
Over 12 Months	102	173
Total	312	300
Gross Unrealized Losses
Less than 12 Months	(4)	(1)
Over 12 Months	(4)	(15)
Total	(8)	$ (16)
Corporate debt
Fair Value
Less than 12 Months	61
Over 12 Months	0
Total	61
Gross Unrealized Losses
Less than 12 Months	(1)
Over 12 Months	0
Total	(1)
Other securities/Sovereign debt
Fair Value
Less than 12 Months	0
Over 12 Months	0
Total	0
Gross Unrealized Losses
Less than 12 Months	0
Over 12 Months	0
Total	$ 0

AVAILABLE-FOR-SALE SECURITIES57

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Gross Realized Gains (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Gross gains on sales of securities	$ 1	$ 4	$ 6	$ 5
Gross (losses) on sales of securities	1	0	6	1
Net gain on sales of securities	0	4	0	4
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0	(4)	0	(4)
Gain (Loss) on Sale of Investments	$ 0	$ 0	$ 0	$ 0

AVAILABLE-FOR-SALE SECURITIES58

AVAILABLE-FOR-SALE SECURITIES - Collateralized Debt Obligation (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Unrealized Gross Losses	$ (482)	$ (286)

AVAILABLE-FOR-SALE SECURITIES59

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Security Impairment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Impairment losses recognized in earnings on available-for-sale securities	$ 0	$ 4	$ 0	$ 4

HELD-TO-MATURITY SECURITIES - N

HELD-TO-MATURITY SECURITIES - Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended
HELD-TO-MATURITY SECURITIES - Narrative (Details) - USD ($)	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 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	Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	$ 2,049	$ 1,416
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized Cost	8,682	9,091
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value	8,391	8,971
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	1,264	1,019
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, 6-10 years	37	0
Held-to-maturity Securities, Over 10 years	2,262	3,714
Amortized Cost	2,299	3,714
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 6-10 years	37	0
Fair Value, Over 10 years	2,185	3,657
Fair Value	2,222	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	1,677	1,021
Amortized Cost	1,677	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	1,623	1,016
Fair Value	1,623	1,044
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	716	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	130	1
Held-to-maturity Securities, Over 10 years	4,196	3,752
Amortized Cost	4,326	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	127	1
Fair Value, Over 10 years	4,047	3,698
Fair Value	4,174	3,736
Federal agencies, Other agencies
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	64	139
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Held-to-maturity Securities, 1-5 years	13	7
Held-to-maturity Securities, 6-10 years	211	362
Held-to-maturity Securities, Over 10 years	151	163
Amortized Cost	375	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	206	360
Fair Value, Over 10 years	148	161
Fair Value	367	529
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Held-to-maturity Securities [Line Items]
Over 12 Months	2,044	1,411
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Amortized Cost	8,677	9,086
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value	8,386	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	Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 8,298	$ 8,464
Amortized Cost	8,682	9,091
Unrealized Gross Gains	0	4
Unrealized Gross Losses	(291)	(124)
Fair Value	8,391	8,971
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	2,222	3,388
Amortized Cost	2,299	3,714
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(77)	(58)
Fair Value	2,222	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	1,552	974
Amortized Cost	1,677	1,049
Unrealized Gross Gains	0	2
Unrealized Gross Losses	(54)	(7)
Fair Value	1,623	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	4,174	3,709
Amortized Cost	4,326	3,791
Unrealized Gross Gains	0	0
Unrealized Gross Losses	(152)	(55)
Fair Value	4,174	3,736
Federal agencies, Other agencies
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	345	388
Amortized Cost	375	532
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(8)	(4)
Fair Value	367	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	8,293	8,459
Amortized Cost	8,677	9,086
Unrealized Gross Gains	0	4
Unrealized Gross Losses	(291)	(124)
Fair Value	8,386	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 -63

HELD-TO-MATURITY SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value
Less than 12 Months	$ 6,249	$ 7,048
Over 12 Months	2,049	1,416
Total	8,298	8,464
Gross Unrealized Losses
Less than 12 Months	(223)	(84)
Over 12 Months	(68)	(40)
Total	(291)	(124)
Collateralized Mortgage Obligations [Member]
Fair Value
Less than 12 Months	958	2,369
Over 12 Months	1,264	1,019
Total	2,222	3,388
Gross Unrealized Losses
Less than 12 Months	(29)	(26)
Over 12 Months	(48)	(32)
Total	(77)	(58)
Residential Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	1,552	974
Over 12 Months	0	0
Total	1,552	974
Gross Unrealized Losses
Less than 12 Months	(54)	(7)
Over 12 Months	0	0
Total	(54)	(7)
Commercial Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	3,458	3,456
Over 12 Months	716	253
Total	4,174	3,709
Gross Unrealized Losses
Less than 12 Months	(134)	(49)
Over 12 Months	(18)	(6)
Total	(152)	(55)
Federal agencies, Other agencies
Fair Value
Less than 12 Months	281	249
Over 12 Months	64	139
Total	345	388
Gross Unrealized Losses
Less than 12 Months	(6)	(2)
Over 12 Months	(2)	(2)
Total	(8)	(4)
Total U.S. Treasury, Federal agency and other agency securities
Fair Value
Less than 12 Months	6,249	7,048
Over 12 Months	2,044	1,411
Total	8,293	8,459
Gross Unrealized Losses
Less than 12 Months	(223)	(84)
Over 12 Months	(68)	(40)
Total	(291)	(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	Jun. 30, 2018	Dec. 31, 2017
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	$ 596	$ 600
Other Securities, Fair Value	597	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	1	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	282	287
Other Securities, Fair Value	282	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 SECURITIZATION65

LOAN SALES AND SECURITIZATIONS - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Residential Mortgage
Servicing Assets at Fair Value [Line Items]
Servicing income	$ 15	$ 14	$ 29
Unpaid principal balance of third party serviced loans	20,200		20,200	$ 19,800
Automobile
Servicing Assets at Fair Value [Line Items]
Servicing income	3	5	6
Unpaid principal balance of third party serviced loans	800		800	1,000
Small Business Association (SBA) Loan
Servicing Assets at Fair Value [Line Items]
Servicing income	3	$ 3	6
Unpaid principal balance of third party serviced loans	$ 1,500		$ 1,500	$ 1,400

LOAN SALES AND SECURITIZATION66

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio (Details) - Residential Mortgage - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Servicing Asset at Amortized Cost [Line Items]
Loans sold with servicing retained	$ 897	$ 798	$ 1,740	$ 1,646
Pretax gains resulting from above loan sales	$ 19	$ 17	$ 40	$ 39

LOAN SALES AND SECURITIZATION67

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Fair Value Method (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Residential Mortgage
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, end of period:	$ 11	$ 13

LOAN SALES AND SECURITIZATION68

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 248		$ 248		$ 238
Residential Mortgage
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	200	$ 178	191	$ 172
New servicing assets created	11	8	20	18
Impairment recovery (charge)	0	(3)	(7)	(1)
Amortization and other	(7)	(7)	(14)	(13)
Carrying value, end of period	204	176	204	176
Fair value, end of period	$ 212	$ 177	$ 212	$ 177
Residential Mortgage \| Amortization method
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Weighted-average life (years)	7 years	7 years 1 month	7 years	7 years 1 month

LOAN SALES AND SECURITIZATION69

LOAN SALES AND SECURITIZATIONS LOAN SALES AND SECURTIZIATIONS - Residential Mortgage Portfolio, MSRs Fair Value Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 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 SECURITIZATION70

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
	Jun. 30, 2018	Dec. 31, 2017
Servicing Asset at Amortized Cost [Line Items]
Constant prepayment rate (annualized), actual	8.50%	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	9.52%	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 SECURITIZATION71

LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 248		$ 248		$ 238
Automobile
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	6	$ 15	8	$ 18
Amortization and other	(1)	(3)	(3)	(6)
Fair value, end of period	5	12	5	12
Carrying value, end of period	$ 5	$ 12	$ 5	$ 12
Automobile \| Amortization method
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Weighted-average life (years)	3 years 2 months	3 years 9 months	3 years 2 months	3 years 9 months

LOAN SALES AND SECURITIZATION72

LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortizations Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 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 SECURITIZATION73

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio (Details) - Small Business Association (SBA) Loan - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Transfer of Financial Assets Accounted for as Sales [Line Items]
Loans with servicing retained sold	$ 97	$ 88	$ 161	$ 165
Pretax gains resulting from above loan sales	$ 10	$ 7	$ 17	$ 13

LOAN SALES AND SECURITIZATION74

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 248		$ 248		$ 238
Small Business Association (SBA) Loan
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	28	$ 21	27	$ 21
New servicing assets created	3	4	5	6
Amortization and other	(3)	(2)	(4)	(4)
Carrying value, end of period	28	23	28	23
Fair value, end of period	$ 33	$ 27	$ 33	$ 27
Weighted-average life (years)	3 years 5 months	3 years 4 months	3 years 5 months	3 years 4 months

LOAN SALES AND SECURITIZATION75

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio, MSRs Amortization Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 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%

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details) - Senior Notes - USD ($)	6 Months Ended
LONG-TERM DEBT (Details) - Senior Notes - USD ($)	Jun. 30, 2018	May 08, 2018
Huntington National Bank Senior Note Due May 2025, 4.00 Percent
Debt Instrument [Line Items]
Debt face amount		$ 500,000,000
Debt percent of value		99.686%
Debt stated interest rate		4.00%
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Issuance Costs, Gross	$ 1,000,000
Huntington National Bank Senior Note Due May 2021, 3.25 Percent
Debt Instrument [Line Items]
Debt face amount		$ 750,000,000
Debt percent of value		99.774%
Debt stated interest rate		3.25%
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Issuance Costs, Gross	$ 2,000,000

OTHER COMPREHENSIVE INCOME - Ac

OTHER COMPREHENSIVE INCOME - Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pretax
Other comprehensive income (loss), pretax	$ (67)	$ 62	$ (257)	$ 78
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	15	(22)	56	(27)
After-tax
Other comprehensive income (loss), net of tax	(52)	40	(201)	51
Accumulated OTTI
Pretax
Other comprehensive income (loss), pretax	0	2	0	3
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	0	(1)	0	(1)
After-tax
Other comprehensive income (loss), net of tax	0	1	0	2
Unrealized gains and (losses) on debt securities \| Debt Securities
Pretax
Other comprehensive income (loss), before reclassifications, before tax	(71)	53	(277)	62
Reclassification adjustment, before tax	3	4	18	10
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	15	(19)	59	(22)
Reclassification adjustment, tax	0	(1)	(3)	(3)
After-tax
Other comprehensive income (loss), before reclassifications, net of tax	(56)	34	(218)	40
Reclassification adjustment, net of tax	3	3	15	7
Other comprehensive income (loss), net of tax	(53)	38	(203)	49
Unrealized gains and (losses) on debt securities and Accumulated OTTI \| Debt Securities
Pretax
Other comprehensive income (loss), pretax	(68)	59	(259)	75
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	15	(21)	56	(26)
Unrealized gains and (losses) on cash flow hedging derivatives
Pretax
Other comprehensive income (loss), before reclassifications, before tax		2		0
Reclassification adjustment, before tax		0		1
Other comprehensive income (loss), pretax		2		1
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax		(1)		0
Reclassification adjustment, tax		0		0
Total other comprehensive income (loss), tax (expense) benefit		(1)		0
After-tax
Other comprehensive income (loss), before reclassifications, net of tax		1		0
Reclassification adjustment, net of tax		0		1
Other comprehensive income (loss), net of tax		1		1
Unrealized gains (losses) for pension and other post- retirement obligations
Pretax
Other comprehensive income (loss), pretax	1	1	2	2
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	0	0	0	(1)
After-tax
Other comprehensive income (loss), net of tax	$ 1	$ 1	$ 2	$ 1

OTHER COMPREHENSIVE INCOME OTHE

OTHER COMPREHENSIVE INCOME OTHER COMPREHENSIVE INCOME - AOCI Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			$ 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	(218)	$ 42
Amounts reclassified from accumulated OCI to earnings	17	9
Period change		51
Balance, end of period	11,472	10,654	10,814
Unrealized gains and (losses) on debt securities \| Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(193)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	(1)
Other comprehensive income before reclassifications	(218)	42
Amounts reclassified from accumulated OCI to earnings	15	7
Period change	(203)	49
Balance, end of period	(482)	(144)	(278)
Unrealized gains and (losses) on cash flow hedging derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(3)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated OCI to earnings	0	1
Period change	0	1
Balance, end of period	0	(2)	0
Unrealized gains (losses) for pension and other post- retirement obligations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(205)
Other comprehensive income before reclassifications	0	0
Amounts reclassified from accumulated OCI to earnings	2	1
Period change	2	1
Balance, end of period	(248)	(204)	(250)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(401)
Period change	(201)
Balance, end of period	(730)	(350)	(528)
Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net unrealized loss on securities transfer	$ (144)	$ 98	$ (95)

OTHER COMPREHENSIVE INCOME - Re

OTHER COMPREHENSIVE INCOME - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest income - held-to-maturity securities - taxable	$ 53	$ 44	$ 107	$ 89
Noninterest income - net gains (losses) on sale of securities	0	4	0	4
Interest income - loans and leases	810	700	1,566	1,376
Noninterest income - other income	45	50	87	96
Noninterest expense - personnel costs	(396)	(392)	(772)	(774)
Income before income taxes	412	351	797	618
Provision for income taxes	(57)	(79)	(116)	(138)
Net income applicable to common shares	334	253	648	442
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)	(2)	(6)	(6)
Noninterest income - net gains (losses) on sale of securities	0	2	(12)	0
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	(4)	0	(4)
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	(3)	(4)	(18)	(10)
Provision for income taxes	0	1	3	3
Net income applicable to common shares	(3)	(3)	(15)	(7)
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)
Noninterest income - other income			0	0
Income before income taxes			0	(1)
Provision for income taxes			0	0
Net income applicable to common shares			0	(1)
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	(1)	(2)	(3)	(3)
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	0	1	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)	(1)	(2)	(2)
Provision for income taxes	0	0	0	1
Net income applicable to common shares	$ (1)	$ (1)	$ (2)	$ (1)

SHAREHOLDERS' EQUITY (Details)

SHAREHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Feb. 27, 2018	Feb. 22, 2018	Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items]
Stock Issued During Period, Value, New Issues		$ 495
Preferred Stock, Shares Outstanding	740,500	740,500			1,098,006
Preferred Stock, Value, Outstanding	$ 1,203	$ 1,203
Preferred Stock, Value, Issued	$ 1,203	$ 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	35,500
Preferred Stock, Value, Outstanding	$ 23	$ 23
Preferred Stock, Dividend Payment Rate, Variable	3-mo. LIBOR + 270 bps
Preferred Stock, Redemption Date	Jan. 15, 2017
Preferred Class A [Member]
Equity, Class of Treasury Stock [Line Items]
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	100,000
Preferred Stock, Value, Outstanding	$ 100	$ 100
Preferred Stock, Dividend Payment Rate, Variable	.05875
Preferred Stock, Redemption Date	Jan. 15, 2022
Series E Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Stock Issued During Period, Value, New Issues		$ 495
Preferred Stock, Liquidation Preference Per Share			$ 100,000
Depositary Shares, Liquidation Preference Per Share			$ 1,000
Preferred Stock, Shares Outstanding	5,000	5,000
Preferred Stock, Value, Outstanding	$ 495	$ 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	400,000
Preferred Stock, Value, Outstanding	$ 386	$ 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	200,000
Preferred Stock, Value, Outstanding	$ 199	$ 199

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic earnings per common share:
Net income	$ 355	$ 272	$ 681	$ 480
Preferred stock dividends	(21)	(19)	(33)	(38)
Net income available to common shareholders	334	253	648	442
Effect of assumed preferred stock conversion	0	0	0	0
Net income applicable to diluted earnings per share	$ 334	$ 253	$ 648	$ 442
Average common shares issued and outstanding (in shares)	1,103,337	1,088,934	1,093,587	1,087,654
Basic earnings per common share (in usd per share)	$ 0.30	$ 0.23	$ 0.59	$ 0.41
Dilutive potential common shares:
Stock options and restricted stock units and awards	15,803	16,329	17,830	17,734
Shares held in deferred compensation plans	3,472	3,108	3,350	3,030
Dilutive impact of Preferred Stock	0	0	8,879	0
Other	0	156	0	154
Dilutive potential common shares	19,275	19,593	30,059	20,918
Total diluted average common shares issued and outstanding (in shares)	1,122,612	1,108,527	1,123,646	1,108,572
Diluted earnings per common share (in usd per share)	$ 0.30	$ 0.23	$ 0.58	$ 0.40
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options outstanding to purchase common stock shares having antidilutive effect	2,500	2,600	1,600	1,800

NON-INTEREST INCOME - Summary o

NON-INTEREST INCOME - Summary of Noninterest Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue from Contract with Customer [Abstract]
Noninterest income from contracts with customers	$ 217		$ 431
Noninterest income within the scope of other GAAP topics	119		219
Total noninterest income	$ 336	$ 325	$ 650	$ 638

NON-INTEREST INCOME - Disaggreg

NON-INTEREST INCOME - Disaggregation by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	$ 217		$ 431
Noninterest income within the scope of other GAAP topics	119		219
Noninterest income	336	$ 325	650	$ 638
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	91		177
Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	52		101
Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	42		86
Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	21		42
Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	11		25
Operating Segments \| Consumer And Business Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	146		286
Noninterest income within the scope of other GAAP topics	41		75
Noninterest income	187	184	361	355
Operating Segments \| Consumer And Business Banking [Member] \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	72		140
Operating Segments \| Consumer And Business Banking [Member] \| Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	49		96
Operating Segments \| Consumer And Business Banking [Member] \| Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	5		12
Operating Segments \| Consumer And Business Banking [Member] \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	10		18
Operating Segments \| Consumer And Business Banking [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	10		20
Operating Segments \| Commercial Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	23		42
Noninterest income within the scope of other GAAP topics	57		107
Noninterest income	80	69	149	134
Operating Segments \| Commercial Banking [Member] \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	16		32
Operating Segments \| Commercial Banking [Member] \| Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	3		5
Operating Segments \| Commercial Banking [Member] \| Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2		2
Operating Segments \| Commercial Banking [Member] \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1		2
Operating Segments \| Commercial Banking [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1		1
Operating Segments \| Vehicle Finance [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2		4
Noninterest income within the scope of other GAAP topics	0		2
Noninterest income	2	3	6	8
Operating Segments \| Vehicle Finance [Member] \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2		3
Operating Segments \| Vehicle Finance [Member] \| Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		0
Operating Segments \| Vehicle Finance [Member] \| Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		0
Operating Segments \| Vehicle Finance [Member] \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		0
Operating Segments \| Vehicle Finance [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		1
Operating Segments \| Regional Banking and The Huntington Private Client Group [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	46		97
Noninterest income within the scope of other GAAP topics	2		1
Noninterest income	48	47	98	94
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		2
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		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	35		72
Operating Segments \| Regional Banking and The Huntington Private Client Group [Member] \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	10		21
Operating Segments \| Regional Banking and The Huntington Private Client Group [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		2
Treasury / Other
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		2
Noninterest income within the scope of other GAAP topics	19		34
Noninterest income	19	$ 22	36	$ 47
Treasury / Other \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		0
Treasury / Other \| Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		0
Treasury / Other \| Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		0
Treasury / Other \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	0		1
Treasury / Other \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	$ 0		$ 1

BENEFIT PLANS - Narrative (Deta

BENEFIT PLANS - Narrative (Details)	3 Months Ended
BENEFIT PLANS - Narrative (Details)	Jun. 30, 2018year
Defined Contribution Plan [Abstract]
Match - Base pay contributed to the plan	matches participant contributions 150% of the first 2% of base pay and 100% of the next 2%.
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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Benefits
Components of net periodic benefit expense [Abstract]
Service cost	$ 1	$ 1	$ 2	$ 1
Interest cost	7	7	14	15
Expected return on plan assets	(12)	(14)	(24)	(28)
Amortization of prior service cost	0	0	0	0
Amortization of gain (loss)	2	2	4	4
Settlements	2	3	4	5
Net periodic (benefit) cost	0	(1)	0	(3)
Post Retirement Benefits
Components of net periodic benefit expense [Abstract]
Service cost	0	0	0	0
Interest cost	0	0	0	0
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	0	(1)	(1)	(1)
Amortization of gain (loss)	0	0	0	0
Settlements	0	0	0	0
Net periodic (benefit) cost	$ 0	$ (1)	$ (1)	$ (1)

BENEFIT PLANS - Costs of Retire

BENEFIT PLANS - Costs of Retirement Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 17	$ 11	$ 28	$ 22

FAIR VALUES OF ASSETS AND LIA87

FAIR VALUES OF ASSETS AND LIABILITIES - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 643	$ 413
Loans Receivable, Fair Value Disclosure	$ 84	$ 93

FAIR VALUES OF ASSETS AND LIA88

FAIR VALUES OF ASSETS AND LIABILITIES - Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	$ 643	$ 413
Consumer loans	84	93
Trading account securities	85	86
Available-for-sale securities	14,070	14,869
Other Securities, Fair Value	597	600
Gross amounts of recognized assets	454	322
Derivative assets netting	(275)	(190)
Net amounts of assets presented in the condensed consolidated balance sheets	179	132
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	406	331
Gross amounts offset in the condensed consolidated balance sheets	(204)	(245)
Derivative liabilities	202	86
U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	6	5
Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	183	70
Municipal securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	3,765	3,878
Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	373	467
Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	87	109
Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	659	1,367
Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,743	2,487
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis
Loans Held-for-sale, Fair Value Disclosure	643	413
Trading account securities	85	86
Available-for-sale securities	14,070	14,869
Other Securities, Fair Value	21	19
MSRs	11	11
Derivative assets netting	(275)	(190)
Net amounts of assets presented in the condensed consolidated balance sheets	179	132
Liabilities measured at fair value on a recurring basis
Gross amounts offset in the condensed consolidated balance sheets	(204)	(245)
Derivative liabilities	202	86
Fair Value, Measurements, Recurring \| U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	6	5
Fair Value, Measurements, Recurring \| Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	7,250	6,484
Fair Value, Measurements, Recurring \| Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	183	70
Fair Value, Measurements, Recurring \| Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	5
Available-for-sale securities	3,765	3,878
Fair Value, Measurements, Recurring \| Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	373	467
Fair Value, Measurements, Recurring \| Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	87	109
Fair Value, Measurements, Recurring \| Other Debt Obligations [Member]
Assets measured at fair value on a recurring basis
Trading account securities	80	86
Available-for-sale securities	4	2
Fair Value, Measurements, Recurring \| Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	659	1,367
Fair Value, Measurements, Recurring \| Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,743	2,487
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	78	83
Available-for-sale securities	6	5
Other Securities, Fair Value	21	19
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
Fair Value, Measurements, Recurring \| Level 1 \| U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	6	5
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	78	83
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	643	413
Consumer loans	50	55
Trading account securities	7	3
Available-for-sale securities	10,886	11,673
MSRs	0	0
Gross amounts of recognized assets	446	316
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	399	326
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	7,250	6,484
Fair Value, Measurements, Recurring \| Level 2 \| Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	183	70
Fair Value, Measurements, Recurring \| Level 2 \| Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	5
Available-for-sale securities	587	711
Fair Value, Measurements, Recurring \| Level 2 \| Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	373	443
Fair Value, Measurements, Recurring \| Level 2 \| Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	87	109
Fair Value, Measurements, Recurring \| Level 2 \| Other Debt Obligations [Member]
Assets measured at fair value on a recurring basis
Trading account securities	2	3
Available-for-sale securities	4	2
Fair Value, Measurements, Recurring \| Level 2 \| Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	659	1,367
Fair Value, Measurements, Recurring \| Level 2 \| Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,743	2,487
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	34	38
Trading account securities	0	0
Available-for-sale securities	3,178	3,191
MSRs	11	11
Gross amounts of recognized assets	8	6
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	7	5
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	3,178	3,167
Fair Value, Measurements, Recurring \| Level 3 \| Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	24
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 LIA89

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	$ 1	$ 3	$ 1	$ 3	$ (1)	$ (2)
Available-for-sale securities	14,070		14,070		14,869
Assets Level 3 Roll Forward:
Transfers into Level 3			0	0
Transfers out of Level 3 (1)			(14)	(3)
Total gains/losses for the period:
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings			16	8
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Other Comprehensive Income (Loss)			0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases			0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Sales			0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements			0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)			2	8
MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance	12	13	11	14
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	(1)	0	0	(1)
Included in OCI	0	0	0	0
Purchases/originations	0	0	0	0
Sales	0	0	0	0
Repayments	0	0	0	0
Settlements	0	0	0	0
Closing balance	11	13	11	13
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	(1)	0	0	(1)
Derivative instruments
Assets Level 3 Roll Forward:
Opening balance	0	3
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	9	2
Total gains/losses for the period:
Included in earnings	10	2
Included in OCI	0	0
Purchases/originations	0	0
Sales	0	0
Repayments	0	0	0	0
Settlements	0	0
Closing balance	1	3	1	3
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	2	3
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance	3,230	2,868	3,167	2,798
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	(1)	(1)	(2)	(3)
Included in OCI	(9)	12	(37)	33
Purchases/originations	86	115	279	248
Sales	0	0	0	0
Repayments	0	0	0	0
Settlements	(128)	(122)	(229)	(204)
Closing balance	3,178	2,872	3,178	2,872
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	12	0	33
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance		59	24	76
Transfers into Level 3		0
Transfers out of Level 3 (1)		0
Total gains/losses for the period:
Included in earnings		(3)	(2)	(3)
Included in OCI		6	11	9
Purchases/originations		0	0	0
Sales		(19)	(33)	(38)
Repayments		0	0	0
Settlements		0	0	(1)
Closing balance	0	43	0	43
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date		6	0	9
Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3			0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance	37	44	38	48
Transfers into Level 3	0	0
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	0	2	0	1
Included in OCI	0	0	0	0
Purchases/originations	0	0	0	0
Sales	0	0	0	0
Repayments	(3)	(2)	(4)	(5)
Settlements	0	0	0	0
Closing balance	34	44	34	44
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	$ 0	0	$ 0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	1,743		1,743		2,487
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	659		659		1,367
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	14,070		14,070		14,869
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	1,743		1,743		2,487
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	659		659		1,367
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	10,886		10,886		11,673
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	1,743		1,743		2,487
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	$ 659		$ 659		$ 1,367

FAIR VALUES OF ASSETS AND LIA90

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings			$ 16	$ 8
MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	$ (1)	$ 0	0	(1)
Mortgage banking income	1	0
Securities gains (losses)	0	0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	(1)	0
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Noninterest income		0
Derivative Financial Instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	(10)	(2)
Securities gains (losses)	0	0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	(10)	(2)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Noninterest income		0
Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	(1)	(1)	(2)	(3)
Mortgage banking income	0	0
Securities gains (losses)	0	(1)
Other expense	(1)		(2)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	1	1
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Noninterest income		0
Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(3)	(2)	(3)
Mortgage banking income		0
Securities gains (losses)		(3)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings		3
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Noninterest income		0
Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	0	2	0	1
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	(2)
Mortgage Banking Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings			16	8
Mortgage Banking Income [Member] \| MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			0	(1)
Mortgage Banking Income [Member] \| Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			0	0
Mortgage Banking Income [Member] \| Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			0	0
Mortgage Banking Income [Member] \| Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			0	0
Securities Gain (Losses) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings			0	0
Securities Gain (Losses) [Member] \| MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			0	0
Securities Gain (Losses) [Member] \| Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			0	(3)
Securities Gain (Losses) [Member] \| Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			(2)	(3)
Securities Gain (Losses) [Member] \| Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings			$ 0	0
Noninterest Income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings				0
Noninterest Income \| MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0
Noninterest Income \| Municipal securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0
Noninterest Income \| Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0
Noninterest Income \| Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		$ 2		$ 1

FAIR VALUES OF ASSETS AND LIA91

FAIR VALUES OF ASSETS AND LIABILITIES - Fair Value Option (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 643	$ 413
Loans Receivable, Fair Value Disclosure	84	93
Fair Value, Measurements, Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	643	413
Fair Value, Measurements, Recurring \| Mortgages Held For Sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	643	413
Loans Held For Sale Unpaid Principal	625	400
Difference	(18)	(13)
Fair Value, Measurements, Recurring \| Mortgages Held To Maturity
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Receivable, Fair Value Disclosure	84	93
Loans Held To Maturity Unpaid Principal	93	102
Difference	(9)	(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	0	1
Loans Held For Sale Unpaid Principal	0	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	7	10
Loans Held To Maturity Unpaid Principal	8	11
Difference	$ (1)	$ (1)

FAIR VALUES OF ASSETS AND LIA92

FAIR VALUES OF ASSETS AND LIABILITIES - Fair Value Option-Changs in Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Measurements, Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) from fair value changes	$ (5)	$ 5	$ (3)	$ (14)
Consumer loans
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) from fair value changes	$ 0	$ (2)	$ 0	$ (1)

FAIR VALUES OF ASSETS AND LIA93

FAIR VALUES OF ASSETS AND LIABILITIES - Non-Recurring Basis (Details) - USD ($) $ in Millions		Jun. 30, 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]	709	488
Available-for-sale securities		14,070	14,869
Long-term debt		9,726	9,206
Held-to-maturity securities		8,682	9,091
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		71,665	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		713	491
Available-for-sale securities		14,070	14,869
Long-term debt		9,889	9,402
Held-to-maturity securities		8,391	8,971
Other Securities		597	600
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		70,996	69,146
Level 1 \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		78
Loans held for sale		0	0
Available-for-sale securities		6	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		7
Loans held for sale		643	413
Available-for-sale securities		10,886	11,673
Long-term debt		9,416	8,944
Held-to-maturity securities		8,391	8,971
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		50	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		70	78
Available-for-sale securities		3,178	3,191
Long-term debt		473	458
Held-to-maturity securities		0	0
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		70,946	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		(55)
Other real estate owned		(28)
Nonrecurring Basis \| Total Gains/(Losses)
Assets measured at fair value on a nonrecurring basis
Impaired loans		0
Other real estate owned		1
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		(55)
Other real estate owned		$ (28)

[1]	Amounts represent loans for which Huntington has elected the fair value option.

FAIR VALUES OF ASSETS AND LIA94

FAIR VALUES OF ASSETS AND LIABILITIES - Significant Unobservable Level 3 Inputs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Gross amounts of recognized assets	$ 454	$ 322
Derivative Liability, Fair Value, Gross Liability	406	331
Available-for-sale securities	14,070	14,869
Consumer loans	84	93
Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
MSRs	11	11
Available-for-sale securities	14,070	14,869
Fair Value, Measurements, Recurring \| Level 3
Fair Value Disclosures [Abstract]
MSRs	11	11
Gross amounts of recognized assets	8	6
Derivative Liability, Fair Value, Gross Liability	7	5
Available-for-sale securities	3,178	3,191
Consumer loans	34	38
Fair Value, Measurements, Nonrecurring
Fair Value Disclosures [Abstract]
Impaired loans Fair Value Disclosure		36
Accrued income and other assets Fair Value Disclosure		33
Fair Value, Measurements, Nonrecurring \| Level 3
Fair Value Disclosures [Abstract]
MSRs		190
Asset-backed securities
Fair Value Disclosures [Abstract]
Available-for-sale securities	373	467
Asset-backed securities \| Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
Available-for-sale securities	373	467
Asset-backed securities \| Fair Value, Measurements, Recurring \| Level 3
Fair Value Disclosures [Abstract]
Available-for-sale securities	0	24
Municipal securities
Fair Value Disclosures [Abstract]
Available-for-sale securities	3,765	3,878
Municipal securities \| Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
Available-for-sale securities	3,765	3,878
Municipal securities \| Fair Value, Measurements, Recurring \| Level 3
Fair Value Disclosures [Abstract]
Available-for-sale securities	$ 3,178	$ 3,167
Cost Approach Valuation Technique \| Maximum \| Fair Value, Measurements, Recurring \| MSRs \| Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	44.00%	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	0.19%	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	8.00%	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	0.40%	4.00%
Cumulative default	0.40%	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	9.00%	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 instruments \| Level 3
Fair Value Disclosures [Abstract]
Net market price	8.00%	20.00%
Estimated Pull through %	100.00%	100.00%
Market Approach Valuation Technique \| Minimum \| Fair Value, Measurements, Recurring \| Derivative instruments \| Level 3
Fair Value Disclosures [Abstract]
Net market price	(5.00%)	(5.00%)
Estimated Pull through %	2.00%	3.00%
Market Approach Valuation Technique \| Weighted Average \| Fair Value, Measurements, Recurring \| Derivative instruments \| Level 3
Fair Value Disclosures [Abstract]
Net market price	2.00%	2.00%
Estimated Pull through %	90.00%	75.00%
Derivative Financial Instruments, Liabilities [Member] \| Market Approach Valuation Technique \| Minimum \| Level 3
Fair Value Disclosures [Abstract]
Fair Value Inputs, Estimated conversion factor	163.00%	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		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 LIA95

FAIR VALUES OF ASSETS AND LIABILITIES - Balance Sheet Location (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Financial Assets:
Trading account securities		$ 85	$ 86
Available-for-sale securities		14,070	14,869
Held-to-maturity securities		8,682	9,091
Loans held for sale	[1]	709	488
Net loans and direct financing leases		71,665	69,426
Derivatives		179	132
Financial Liabilities:
Deposits		79,587	77,041
Short-term borrowings		2,442	5,056
Long-term borrowings		9,726	9,206
Derivatives		202	86
Reported Value Measurement [Member]
Financial Assets:
Cash and short term assets			1,567
Trading account securities		85	86
Available-for-sale securities		14,070	14,869
Held-to-maturity securities		8,682
Other Securities		597	600
Loans held for sale		709
Net loans and direct financing leases			69,426
Derivatives			132
Financial Liabilities:
Deposits		79,587	77,041
Short-term borrowings		2,442	5,056
Long-term borrowings		9,726	9,206
Derivatives		202	86
Estimate of Fair Value Measurement [Member]
Financial Assets:
Cash and short term assets		1,423
Trading account securities		85	86
Available-for-sale securities		14,070	14,869
Held-to-maturity securities		8,391	8,971
Other Securities		597	600
Loans held for sale		713	491
Other securities		21	19
Net loans and direct financing leases		70,996	69,146
Derivatives			132
Financial Liabilities:
Deposits		79,534	77,010
Short-term borrowings		2,442	5,056
Long-term borrowings		9,889	9,402
Estimate of Fair Value Measurement [Member] \| Level 1
Financial Assets:
Trading account securities		78
Available-for-sale securities		6	5
Held-to-maturity securities		0	0
Loans held for sale		0	0
Other securities		21	19
Net loans and direct financing leases		0	0
Financial Liabilities:
Deposits		0	0
Short-term borrowings		2	0
Long-term borrowings		0	0
Estimate of Fair Value Measurement [Member] \| Level 2
Financial Assets:
Trading account securities		7
Available-for-sale securities		10,886	11,673
Held-to-maturity securities		8,391	8,971
Loans held for sale		643	413
Other securities		0	0
Net loans and direct financing leases		50	0
Financial Liabilities:
Deposits		73,371	73,975
Short-term borrowings		0	0
Long-term borrowings		9,416	8,944
Estimate of Fair Value Measurement [Member] \| Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		3,178	3,191
Held-to-maturity securities		0	0
Loans held for sale		70	78
Other securities		0	0
Net loans and direct financing leases		70,946	69,146
Financial Liabilities:
Deposits		6,163	3,035
Short-term borrowings		2,440	5,056
Long-term borrowings		473	458
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account securities		85	86
Available-for-sale securities		14,070	14,869
Derivatives		179	132
Financial Liabilities:
Derivatives		202	86
Fair Value, Measurements, Recurring [Member] \| Level 1
Financial Assets:
Trading account securities		78	83
Available-for-sale securities		6	5
Fair Value, Measurements, Recurring [Member] \| Level 2
Financial Assets:
Trading account securities		7	3
Available-for-sale securities		10,886	11,673
Fair Value, Measurements, Recurring [Member] \| Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		3,178	3,191
Other Debt Obligations [Member] \| Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account securities		80	86
Available-for-sale securities		4	2
Other Debt Obligations [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 1
Financial Assets:
Trading account securities		78	83
Available-for-sale securities		0	0
Other Debt Obligations [Member] \| Fair Value, Measurements, Recurring [Member] \| Level 2
Financial Assets:
Trading account securities		2	3
Available-for-sale securities		4	2
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		1,423	1,567
Held-to-maturity securities		8,682	9,091
Other Securities		576	581
Net loans and direct financing leases		71,581	69,333
Financial Liabilities:
Deposits		79,587	77,041
Short-term borrowings		2,442	5,056
Long-term borrowings		9,726	9,206
Fair Value Fair Value Option [Member] \| Reported Value Measurement [Member]
Financial Assets:
Trading account securities		85	86
Available-for-sale securities		14,070	14,869
Other Securities		21	19
Loans held for sale		643	413
Net loans and direct financing leases		84	93
Derivatives		179	132
Financial Liabilities:
Derivatives		202	86
LowerOfCostOrMarket [Member] \| Reported Value Measurement [Member]
Financial Assets:
Loans held for sale		$ 66	$ 75

[1]	Amounts represent loans for which Huntington has elected the fair value option.

DERIVATIVE FINANCIAL INSTRUME96

DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)group	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Derivative [Line Items]
Fair value hedging adjustments			$ 144
Increase (decrease) to net interest income due to derivative adjustment	$ (15)	$ 6	(14)	$ 16
Derivative Liability	202		202		$ 86
Purchase of interest rate caps and derivative financial instruments, notional value	5,377		5,377		8,375
Total notional amount corresponds to trading assets, fair value (less than)	0		0		3
Credit risks from interest rate swaps used for trading purposes	$ 101		$ 101		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 June 30, 2018 and December 31, 2017 . June 30, 2018 Weighted-Average Rate (dollar amounts in millions) Notional Value Average Maturity (years) Fair Value Receive Pay Asset conversion swaps Receive fixed—generic $ 12 1.7 $ — 2.20 % 2.07 % Liability conversion swaps Receive fixed—generic 5,365 2.2 (50 ) 1.93 2.27 Total swap portfolio at June 30, 2018 $ 5,377 2.2 $ (50 ) 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	$ 28		$ 28		30
Investment securities and cash collateral pledged by Huntington	64		64
Investment securities and cash collateral pledged to Huntington	200		$ 200
liability conversion swaps (notional value)	2,900
Liability conversion swap (adjusted basis)	149
Swap
Derivative [Line Items]
Additional information about interest rate swaps used in asset and liability management activities [Table Text Block]			7
Derivative used in trading activity
Derivative [Line Items]
Net derivative asset (liability)	99		$ 99		88
Derivative financial instruments used by Huntington on behalf of customers including offsetting derivatives, notional value	24,000		24,000		22,000
Derivative used in Mortgage Banking Activities
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	0		0		188
Gains (losses) related to derivative instruments Included in total MSR	0	$ 2	(8)	$ 1
Fair Value Hedging
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	5,365		5,365		8,375
Cash Flow Hedging
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	$ 12		$ 12		$ 0

DERIVATIVE FINANCIAL INSTRUME97

DERIVATIVE FINANCIAL INSTRUMENTS - Hedging Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 5,377	$ 8,375
Asset derivatives included in accrued income and other assets
Total contracts	454	322
Liability derivatives included in accrued expenses and other liabilities
Total contracts	406	331
Accrued income and other assets
Asset derivatives included in accrued income and other assets
Interest rate contracts designated as hedging instruments	16	22
Interest rate contracts not designated as hedging instruments	268	187
Foreign exchange contracts not designated as hedging instruments	32	18
Commodities contracts not designated as hedging instruments	134	92
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	4	3
Total contracts	454	322
Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Interest rate contracts designated as hedging instruments	66	121
Interest rate contracts not designated as hedging instruments	176	100
Foreign exchange contracts not designated as hedging instruments	29	18
Commodities contracts not designated as hedging instruments	129	87
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	6	5
Total contracts	$ 406	$ 331

DERIVATIVE FINANCIAL INSTRUME98

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	2 years 6 months
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 5,377	$ 8,375
Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	5,365	8,375
Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	12	0
Subordinated notes
Notional Disclosures [Abstract]
Derivative, Notional Amount	375	950
Subordinated notes \| Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	375	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	4,990	7,425
Other long-term debt \| Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	4,990	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 8 months 12 days	0 years
Liability conversion swaps Receive Fixed Generic [Member]
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	2 years 2 months 12 days	2 years 6 months

DERIVATIVE FINANCIAL INSTRUME99

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Managemen Add Info (Details Add Info) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative, Notional Amount	$ 5,377,000	$ 8,375,000
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 5,377,000	8,375,000
Average Maturity (years)	2 years 6 months
Fair Value	$ (50,000)	$ (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 8 months 12 days	0 years
Fair Value	$ 0
Weighted-Average Rate Receive	2.20%
Weighted-Average Rate Pay	2.07%
Liability conversion swaps - Receive Fixed - Generic
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 5,365,000	$ 8,375,000
Average Maturity (years)	2 years 2 months 12 days	2 years 6 months
Fair Value	$ (50,000)	$ (99,000)
Weighted-Average Rate Receive	1.93%	1.56%
Weighted-Average Rate Pay	2.27%	1.44%

DERIVATIVE FINANCIAL INSTRUM100

DERIVATIVE FINANCIAL INSTRUMENTS - Gain (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 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-month and six-month periods ended June 30, 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 June 30, 2018 Six Months Ended June 30, 2018 Interest rate contracts: Customer Capital markets fees $ 12 $ 19 Mortgage Banking Mortgage banking income — (8 ) Foreign exchange contracts Capital markets fees 7 12 Commodities contracts Capital markets fees — 2 Equity contracts Other noninterest expense (3 ) (3 ) Total $ 16 $ 22
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	$ 7,000		$ 12,000
Gain (Loss) on Commodity Contract Derivative Instruments Not Designated as Hedging Instruments	0		2,000
Gain (Loss) on Equity Contract Derivative Instruments Not Designated as Hedging Instruments	(3,000)		(3,000)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	16,000		22,000
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	41,000	$ 2,000	24,000	$ (2,000)
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	(42,000)	(2,000)	(24,000)	3,000
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	93,000	16,000	42,000	6,000
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	(90,000)	$ (17,000)	(37,000)	$ (8,000)
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	12,000		19,000
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ 0		$ (8,000)
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 INSTRUM101

DERIVATIVE FINANCIAL INSTRUMENTS - Fair Value Hedges (Details) $ in Millions	Jun. 30, 2018USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge Liabilities	$ 5,302
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	$ (55)

DERIVATIVE FINANCIAL INSTRUM102

DERIVATIVE FINANCIAL INSTRUMENTS - Mortgage Banking Activities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Derivative assets:
Total derivative assets	$ 454		$ 454		$ 322
Derivative liabilities:
Total derivative liabilities	(406)		(406)		(331)
Interest rate lock agreements
Derivative assets:
Total derivative assets	8		8		6
Derivative liabilities:
Total derivative liabilities	0		0		0
Forward trades and options
Derivative assets:
Total derivative assets	0		0		1
Derivative liabilities:
Total derivative liabilities	5		5		0
Derivative used in Mortgage Banking Activities
Derivatives, Fair Value [Line Items]
Gains losses related to derivative instruments Included in Mortgage securities	0	$ 2	(8)	$ 1
Derivative assets:
Total derivative assets	8		8		7
Derivative liabilities:
Total derivative liabilities	$ 5		$ 5		$ 0

DERIVATIVE FINANCIAL INSTRUM103

DERIVATIVE FINANCIAL INSTRUMENTS - MSR Hedging Activities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 5,377		$ 5,377		$ 8,375
Notional amount corresponds to trading assets, fair value	0		0		3
Derivative used in Mortgage Banking Activities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	0		0		$ 188
Gains losses related to derivative instruments Included in Mortgage securities	$ 0	$ 2	$ (8)	$ 1

DERIVATIVE FINANCIAL INSTRUM104

DERIVATIVE FINANCIAL INSTRUMENTS - Offsetting Assets (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets	$ 454	$ 322
Gross amounts offset in the condensed consolidated balance sheets	275	190
Net amounts of assets presented in the condensed consolidated balance sheets	179	132
Gross amounts not offset in the condensed consolidated balance sheets, Financial instruments	0	(11)
Gross amounts not offset in the condensed consolidated balance sheets, cash collateral received	(61)	(18)
Net amount	$ 118	$ 103

DERIVATIVE FINANCIAL INSTRUM105

DERIVATIVE FINANCIAL INSTRUMENTS - Offsetting Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	$ 406	$ 331
Gross amounts offset in the condensed consolidated balance sheets	(204)	(245)
Derivative liabilities	202	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	(20)	(21)
Net amount	$ 182	$ 65

VIEs - Narrative (Details)

VIEs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
VIEs - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2015	Jun. 30, 2018
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	Jun. 30, 2018	Dec. 31, 2017
Trust 2016 Unconsolidated [Member]
Variable Interest Entity [Line Items]
Total Assets	$ 4	$ 7
Total Liabilities	1	0
Maximum Exposure to Loss	4	7
2015-1 Automobile Trust
Variable Interest Entity [Line Items]
Total Assets	0	1
Total Liabilities	0	0
Maximum Exposure to Loss	0	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	625	636
Total Liabilities	293	335
Maximum Exposure to Loss	625	636
Other Investments
Variable Interest Entity [Line Items]
Total Assets	135	117
Total Liabilities	62	53
Maximum Exposure to Loss	135	117
Total
Variable Interest Entity [Line Items]
Total Assets	778	775
Total Liabilities	608	640
Maximum Exposure to Loss	$ 764	$ 761

VIEs - Trust preferred Securiti

VIEs - Trust preferred Securities (Details) $ in Millions	3 Months Ended
VIEs - Trust preferred Securities (Details) $ in Millions	Jun. 30, 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	3.04%
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	2.96%
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	3.74%
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	3.74%
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	3.67%
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		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Low Income Housing Tax Credit Partnerships
Variable Interest Entity [Line Items]
Affordable housing tax credit investments	$ 1,024		$ 1,024		$ 996
Less: amortization	(399)		(399)		(360)
Net affordable housing tax credit investments	625		625		636
Unfunded commitments	293		293		$ 335
Tax credits and other tax benefits recognized	23	$ 23	46	$ 46
Proportional Amortization Method
Variable Interest Entity [Line Items]
Tax credit amortization expense included in provision for income taxes	$ 20	$ 17	$ 39	$ 34

COMMITMENTS AND CONTINGENT L110

COMMITMENTS AND CONTINGENT LIABILITIES - Commitments to Extend Credit (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Commercial
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	$ 16,641	$ 16,219
Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	14,338	13,384
Commercial Real Estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	1,200	1,366
Standby Letters of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	601	510
Commercial \| Letter of Credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	$ 27	$ 21

COMMITMENTS AND CONTINGENT L111

COMMITMENTS AND CONTINGENT LIABILITIES - Narrative (Details) - USD ($)	3 Months Ended
	Jun. 30, 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	$ 9,000,000	$ 10,000,000
Outstanding standby letters of credit	601,000,000	510,000,000
Commitments to Sell Loans
Loss Contingencies [Line Items]
Commitments to sell residential real estate loans	1,100,000,000	$ 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		6 Months Ended
SEGMENT REPORTING (Details) $ in Millions	Jun. 30, 2018USD ($)reporting_unitsegments	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments \| segments	4
Maximum business banking customer's revenue	$ 20
Net interest income	784	$ 745	$ 1,554	$ 1,475
Provision (reduction in allowance) for credit losses	(56)	(25)	(122)	(93)
Noninterest income	336	325	650	638
Noninterest expense	652	694	1,285	1,402
Provision (benefit) for income taxes	57	79	116	138
Net income	355	272	681	480
Assets	105,358		105,358		$ 104,185
Deposits	79,587		79,587		77,041
Operating Segments \| Consumer & Business Banking
Segment Reporting Information [Line Items]
Net interest income	413	385	808	759
Provision (reduction in allowance) for credit losses	(27)	(17)	(59)	(51)
Noninterest income	187	184	361	355
Noninterest expense	429	413	840	826
Provision (benefit) for income taxes	30	49	57	83
Net income	114	90	213	154
Assets	27,013		27,013		26,220
Deposits	$ 48,186		48,186		45,643
Operating Segments \| Commercial Banking
Segment Reporting Information [Line Items]
Number of reporting units \| reporting_unit	6
Net interest income	$ 229	223	449	452
Provision (reduction in allowance) for credit losses	(18)	5	(39)	(16)
Noninterest income	80	69	149	134
Noninterest expense	128	119	249	236
Provision (benefit) for income taxes	35	62	65	117
Net income	128	116	245	217
Assets	33,036		33,036		32,118
Deposits	21,142		21,142		21,235
Operating Segments \| Vehicle Finance [Member]
Segment Reporting Information [Line Items]
Net interest income	100	106	199	210
Provision (reduction in allowance) for credit losses	(10)	(16)	(23)	(26)
Noninterest income	2	3	6	8
Noninterest expense	38	38	74	74
Provision (benefit) for income taxes	11	19	23	41
Net income	43	36	85	77
Assets	18,590		18,590		17,865
Deposits	340		340		358
Operating Segments \| RBPCG
Segment Reporting Information [Line Items]
Net interest income	46	42	91	83
Provision (reduction in allowance) for credit losses	(1)	3	(1)	0
Noninterest income	48	47	98	94
Noninterest expense	66	61	123	124
Provision (benefit) for income taxes	6	11	13	19
Net income	21	20	52	34
Assets	6,185		6,185		5,821
Deposits	5,985		5,985		6,057
Treasury / Other
Segment Reporting Information [Line Items]
Net interest income	(4)	(11)	7	(29)
Provision (reduction in allowance) for credit losses	0	0	0	0
Noninterest income	19	22	36	47
Noninterest expense	(9)	63	(1)	142
Provision (benefit) for income taxes	(25)	(62)	(42)	(122)
Net income	49	$ 10	86	$ (2)
Assets	20,534		20,534		22,161
Deposits	$ 3,934		$ 3,934		$ 3,748