Huntington Bancshares (HBAN) 10-Q30 Oct 182018 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 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	Sep. 30, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding (in shares)	1,061,529,259

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and due from banks		$ 1,299	$ 1,520
Interest-bearing deposits in banks		43	47
Trading account securities		83	86
Available-for-sale securities		13,727	14,869
Held-to-maturity securities		8,465	9,091
Other securities		565	600
Loans held for sale (includes $727 and $413 respectively, measured at fair value)	[1]	792	488
Loans and leases (includes $81 and $93 respectively, measured at fair value)	[1]	73,370	70,117
Allowance for loan and lease losses		(761)	(691)
Net loans and leases		72,609	69,426
Bank owned life insurance		2,494	2,466
Premises and equipment		827	864
Goodwill		1,993	1,993
Other intangible assets		306	346
Servicing rights		251	238
Accrued income and other assets		2,198	2,151
Total assets		105,652	104,185
Liabilities
Deposits		81,689	77,041
Short-term borrowings		1,348	5,056
Long-term debt		9,385	9,206
Accrued expenses and other liabilities		2,296	2,068
Total liabilities		94,718	93,371
Shareholders’ equity
Preferred stock		1,203	1,071
Common stock		11	11
Capital surplus		9,358	9,707
Less treasury shares, at cost		(44)	(35)
Accumulated other comprehensive loss		(790)	(528)
Retained earnings		1,196	588
Total shareholders’ equity		10,934	10,814
Total liabilities and shareholders’ equity		$ 105,652	$ 104,185
Common shares authorized (par value of $0.01) (in shares)		1,500,000,000	1,500,000,000
Common shares issued (in shares)		1,065,251,488	1,075,294,946
Common shares outstanding (in shares)		1,061,529,259	1,072,026,681
Treasury shares outstanding (in shares)		3,722,229	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 Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets
Loans held for sale, fair value	$ 727	$ 413
Loans and leases, fair value	$ 81	$ 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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest and fee income:
Loans and leases	$ 848	$ 724	$ 2,414	$ 2,100
Available-for-sale securities
Taxable	68	69	209	215
Tax-exempt	24	19	71	56
Held-to-maturity securities—taxable	52	49	159	138
Other securities—taxable	6	5	19	14
Other	9	7	21	16
Total interest income	1,007	873	2,893	2,539
Interest expense:
Deposits	112	50	259	126
Short-term borrowings	9	6	42	17
Subordinated notes and other long-term debt	84	59	236	163
Total interest expense	205	115	537	306
Net interest income	802	758	2,356	2,233
Provision for credit losses	53	43	175	136
Net interest income after provision for credit losses	749	715	2,181	2,097
Service charges on deposit accounts	93	91	270	262
Cards and payment processing income	57	54	166	153
Trust and investment management services	43	39	129	115
Mortgage banking income	31	34	85	98
Insurance income	19	18	61	60
Capital markets fees	22	22	62	53
Bank owned life insurance income	19	16	51	49
Gain on sale of loans and leases	16	14	39	39
Net (losses) gains on sales of securities	(2)	0	(2)	4
Other noninterest income	44	42	131	138
Total noninterest income	342	330	992	967
Personnel costs	388	377	1,160	1,151
Outside data processing and other services	69	80	211	242
Net occupancy	38	55	114	176
Equipment	38	45	116	135
Deposit and other insurance expense	18	19	54	59
Professional services	17	15	43	51
Marketing	12	17	38	50
Amortization of intangibles	13	14	40	42
Other noninterest expense	58	58	160	176
Total noninterest expense	651	680	1,936	2,082
Income before income taxes	440	365	1,237	982
Provision for income taxes	62	90	178	228
Net income	378	275	1,059	754
Dividends on preferred shares	18	19	51	57
Net income applicable to common shares	$ 360	$ 256	$ 1,008	$ 697
Average common shares—basic (in shares)	1,084,536	1,086,038	1,090,570	1,087,115
Average common shares—diluted (in shares)	1,103,740	1,106,491	1,116,978	1,107,878
Per common share:
Net income—basic (in usd per share)	$ 0.33	$ 0.24	$ 0.92	$ 0.64
Net income—diluted (in usd per share)	0.33	0.23	0.90	0.63
Cash dividends declared (in usd per share)	$ 0.14	$ 0.08	$ 0.36	$ 0.24
OTTI losses for the periods presented:
Total OTTI losses	$ 0	$ 0	$ 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	$ 0	$ 0	$ (4)

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 378	$ 275	$ 1,059	$ 754
Unrealized gains (losses) on available-for-sale securities:
Non-credit-related impairment recoveries (losses) on debt securities not expected to be sold	0	0	0	2
Unrealized net gains (losses) on available-for-sale securities arising during the period, net of reclassification for net realized gains and losses	62	22	264	(25)
Total unrealized gains (losses) on available-for-sale securities	(62)	(22)	(264)	27
Unrealized gains (losses) on cash flow hedging derivatives, net of reclassifications to income	0	2	0	2
Change in accumulated unrealized losses for pension and other post-retirement obligations	1	1	3	2
Other comprehensive income (loss), net of tax	(61)	(19)	(261)	31
Comprehensive income	$ 317	$ 256	$ 798	$ 785

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	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	$ 10,308,000	$ 11,000	$ 9,881,000	$ (27,000)	$ (401,000)	$ (227,000)	$ 1,071,000
Comprehensive Income:
Net income	754,000					754,000
Other comprehensive income (loss)	31,000				31,000
Cash dividends declared:
Common stock, dividend	(261,000)					(261,000)
Preferred stock, dividend								$ (23,000)	$ (23,000)	$ (1,000)	$ (1,000)	$ (5,000)	$ (5,000)			$ (28,000)	$ (28,000)
Stock Repurchased and Retired During Period, Shares		9,645
Stock Repurchased and Retired During Period, Value	123,000	$ 0	123,000
Recognition of the fair value of share-based compensation	73,000		73,000
Other share-based compensation activity (in shares)		5,361
Other share-based compensation activity	(20,000)	$ 0	(12,000)			(8,000)
Other (in shares)		10		(468)
Other	(6,000)	$ 0	2,000	$ (8,000)		0
Balance, end of period (in shares) at Sep. 30, 2017		1,084,367		(3,421)
Balance, end of period at Sep. 30, 2017	10,699,000	$ 11,000	9,821,000	$ (35,000)	(370,000)	201,000	1,071,000
Balance, beginning of period (in shares) at Dec. 31, 2017		1,075,295		(3,268)
Balance, beginning of period at Dec. 31, 2017	10,814,000	$ 11,000	9,707,000	$ (35,000)	(528,000)	588,000	1,071,000
Comprehensive Income:
Net income	1,059,000					1,059,000
Other comprehensive income (loss)	(261,000)				(261,000)
Cash dividends declared:
Common stock, dividend	(393,000)					(393,000)
Preferred stock, dividend										$ (2,000)	$ (2,000)	$ (4,000)	$ (4,000)		$ (17,000)	$ (28,000)	$ (28,000)
Stock Issued During Period, Value, New Issues	495,000													$ 495,000
Stock Repurchased and Retired During Period, Shares		46,677
Stock Repurchased and Retired During Period, Value	739,000	$ 0	739,000
Conversion of Stock, Amount Converted	0		(363,000)				(363,000)
Conversion of Stock, Shares		30,330
Recognition of the fair value of share-based compensation	59,000		59,000
Other share-based compensation activity (in shares)		6,303
Other share-based compensation activity	(40,000)	$ 0	(32,000)			(8,000)
Other (in shares)				454
Other	(9,000)		0	$ (9,000)
Balance, end of period (in shares) at Sep. 30, 2018		1,065,251		(3,722)
Balance, end of period at Sep. 30, 2018	10,934,000	$ 11,000	$ 9,358,000	$ (44,000)	$ (790,000)	$ 1,196,000	$ 1,203,000
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	(1,000)
Cumulative Effect of New Accounting Principle in Period of Adoption	$ 0

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash dividends declared:
Common stock, Cash dividend per share (in usd per share)	$ 0.36	$ 0.24
Series A Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	0	63.75
Series B Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	36.51	28.96
Series C Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	44.07	44.07
Series D Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	46.88	46.88
Series E Preferred Stock
Cash dividends declared:
Preferred stock dividend per share (in usd per share)	$ 3,467.50	$ 0

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 1,059	$ 754
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	175	136
Depreciation and amortization	350	307
Share-based compensation expense	59	73
Deferred income tax expense	125	36
Net losses (gains) on sales of securities	2	(4)
Impairment losses recognized in earnings on available-for-sale securities	0	4
Net change in:
Trading account securities	3	45
Loans held for sale	(384)	(164)
Accrued income and other assets	(325)	(137)
Accrued expense and other liabilities	215	42
Other, net	(135)	14
Net cash provided by (used in) operating activities	1,144	1,106
Investing activities
Change in interest bearing deposits in banks	62	21
Proceeds from:
Maturities and calls of available-for-sale securities	1,539	1,081
Maturities of held-to-maturity securities	573	793
Sales of available-for-sale securities	381	1,247
Sales of other securities	40	8
Purchases of available-for-sale securities	(1,044)	(3,169)
Purchases of held-to-maturity securities	(71)	(690)
Purchases of other securities	(5)	(40)
Net proceeds from sales of portfolio loans	461	427
Net loan and lease activity, excluding sales and purchases	(3,583)	(2,159)
Purchases of premises and equipment	(62)	(145)
Purchases of loans and leases	(318)	(113)
Other, net	50	37
Net cash provided by (used in) investing activities	(1,977)	(2,702)
Financing activities
Increase in deposits	4,648	2,837
Decrease in short-term borrowings	(3,613)	(1,865)
Net proceeds from issuance of long-term debt	2,121	1,773
Maturity/redemption of long-term debt	(1,915)	(883)
Dividends paid on preferred stock	(51)	(57)
Dividends paid on common stock	(362)	(262)
Repurchases of common stock	(739)	(123)
Net proceeds from issuance of preferred stock	495	0
Proceeds from issuance of secured financing	50	0
Payments related to tax-withholding for share based compensation awards	(27)	(24)
Proceeds from (Payments for) Other Financing Activities	5	9
Net cash provided by (used for) financing activities	612	1,405
Increase (decrease) in cash a cash equivalents	(221)	(191)
Cash and cash equivalents at beginning of period	1,520	1,385
Cash and cash equivalents at end of period	1,299	1,194
Supplemental disclosures:
Interest paid	527	307
Income taxes (refunded) paid	(112)	71
Non-cash activities
Loans transferred to held-for-sale from portfolio	470	446
Loans transferred to portfolio from held-for-sale	49	5
Transfer of loans to OREO	15	24
Transfer of securities from held-to-maturity to available-for-sale	2,833	0
Transfer of securities from available-for-sale to held-to-maturity	$ 2,707	$ 993

BASIS OF PRESENTATION

BASIS OF PRESENTATION	9 Months Ended
BASIS OF PRESENTATION	Sep. 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.

ACCOUNTING STANDARDS UPDATE

ACCOUNTING STANDARDS UPDATE	9 Months Ended
ACCOUNTING STANDARDS UPDATE	Sep. 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 Note 12 for further detail impact on adoption. ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities. Issued January 2016 - Makes targeted improvements related to certain aspects of recognition, measurement, presentation and disclosures for financial instruments 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 on January 1, 2018 using the modified retrospective approach. - Amendments were applied as a cumulative-effect adjustment to the balance sheet as of January 1, 2018. - 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 from the service cost component in the income statement. - 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 the 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. ASU 2018-15 - Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. Issued August 2018 - Aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software as well as with hosting arrangements that include an internal-use software license. - Requires the entity to expense the capitalized implementation costs of a hosting arrangement over the term of the hosting arrangement. - Requires the entity to present the expense related to implementation costs in the same statement of income line and statement of cash flows line where the fees for the service contract is recognized for respective statements. - Effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years with early adoption permitted. - Huntington early adopted the guidance effective 3Q 2018. The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements as the guidance was consistent with Huntington's existing accounting treatment for such arrangements. 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 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. - Management expects to elect certain practical expedients offered by the FASB, including adopting the standard as of the effective date, and foregoing the restatement of comparative periods. Management also expects to exclude short-term leases from the recognition of right-of-use asset and lease liabilities. Additionally, Huntington will elect the transition relief allowed by FASB in foregoing the reassessment of the following: whether any existing contracts are or contain leases, the classification of existing leases, and the determination of initial direct costs for existing leases. - Huntington expects to recognize right-of-use assets and lease liabilities of less than 1% of total assets, representing substantially all of its operating lease commitments. This estimate is based, primarily, on the present value of unpaid future minimum lease payments. Additionally, that amount may be impacted by assumptions around renewals and/or extensions, actual renewals and extensions before the effective date, the identification of embedded and other leases, and the interest rate used to discount those future lease obligations. 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 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 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. ASU 2018-13 - Fair Value Measurement (Topic 820). Issued August 2018 - Modifies the disclosure requirements on fair value measurements. - Removes disclosures for transfers between Level 1 and Level 2, the policy for timing of transfers between levels, and the valuation processes for Level 3 fair value measurements. - Clarifies that the information about uncertainty in measurement in uncertainty disclosure should be as of the reporting date. - Adds disclosures related to (a) changes in unrealized gains/losses in OCI for Level 3 fair value measurements for assets held at the end of the reporting period, and (b) the process of calculating weighted average for significant unobservable inputs used to develop Level 3 fair value measurements. - Effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years with early adoption permitted. - The amendment is not expected to have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. ASU 2018-14 - Compensation - Retirement Benefits - Defined Benefit Plans. Issued August 2018 - Modifies the disclosure requirements for defined benefit pension plans. - Removes disclosures pertaining to (a) the amounts of AOCI expected to be recognized as pension costs over the next fiscal year, (b) the amount and timing of plan assets expected to be returned to the employer, and (c) the effect of one-percentage-point change in the assumed health care trends on (i) service and interest cost and (ii) postretirement health care benefit obligation. - Adds a new disclosure requiring an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. - Effective retrospectively for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years with early adoption permitted. - The amendment is not expected to have significant impact on the Huntington's Unaudited Condensed Consolidated Financial Statements.

LOANS _ LEASES AND ALLOWANCE FO

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES	9 Months Ended
LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES	Sep. 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 $408 million and $334 million at September 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 September 30, 2018 and December 31, 2017 . (dollar amounts in millions) September 30, 2018 December 31, 2017 Loans and leases: Commercial and industrial $ 29,196 $ 28,107 Commercial real estate 7,073 7,225 Automobile 12,375 12,100 Home equity 9,850 10,099 Residential mortgage 10,459 9,026 RV and marine finance 3,152 2,438 Other consumer 1,265 1,122 Loans and leases $ 73,370 $ 70,117 Allowance for loan and lease losses (761 ) (691 ) Net loans and leases $ 72,609 $ 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 September 30, 2018 and December 31, 2017 . (dollar amounts in millions) September 30, December 31, Commercial and industrial $ 211 $ 161 Commercial real estate 19 29 Automobile 5 6 Home equity 67 68 Residential mortgage 67 84 RV and marine finance 1 1 Other consumer — — Total nonaccrual loans $ 370 $ 349 The following table presents an aging analysis of loans and leases, including past due loans and leases, by loan class at September 30, 2018 and December 31, 2017 : September 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 $ 48 $ 17 $ 58 $ 123 $ 29,073 $ — $ 29,196 $ 9 (2) Commercial real estate 6 1 7 14 7,059 — 7,073 — Automobile 77 16 8 101 12,274 — 12,375 7 Home equity 46 17 60 123 9,725 2 9,850 15 Residential mortgage 116 42 151 309 10,071 79 10,459 117 (3) RV and marine finance 9 2 2 13 3,139 — 3,152 1 Other consumer 13 6 5 24 1,241 — 1,265 5 Total loans and leases $ 315 $ 101 $ 291 $ 707 $ 72,582 $ 81 $ 73,370 $ 154 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 nine-month periods ended September 30, 2018 and 2017 . (dollar amounts in millions) Commercial Consumer Total Three-month period ended September 30, 2018: ALLL balance, beginning of period $ 531 $ 210 $ 741 Loan charge-offs (11 ) (47 ) (58 ) Recoveries of loans previously charged-off 15 14 29 Provision for loan and lease losses 8 41 49 ALLL balance, end of period $ 543 $ 218 $ 761 AULC balance, beginning of period $ 90 $ 3 $ 93 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 5 (1 ) 4 AULC balance, end of period $ 95 $ 2 $ 97 ACL balance, end of period $ 638 $ 220 $ 858 Nine-month period ended September 30, 2018: ALLL balance, beginning of period $ 482 $ 209 $ 691 Loan charge-offs (46 ) (138 ) (184 ) Recoveries of loans previously charged-off 45 44 89 Provision for loan and lease losses 62 103 165 ALLL balance, end of period $ 543 $ 218 $ 761 AULC balance, beginning of period $ 84 $ 3 $ 87 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 11 (1 ) 10 AULC balance, end of period $ 95 $ 2 $ 97 ACL balance, end of period $ 638 $ 220 $ 858 (dollar amounts in millions) Commercial Consumer Total Three-month period ended September 30, 2017: ALLL balance, beginning of period $ 475 $ 193 $ 668 Loan charge-offs (19 ) (46 ) (65 ) Recoveries of loans previously charged-off 10 12 22 Provision for loan and lease losses 8 42 50 ALLL balance, end of period $ 474 $ 201 $ 675 AULC balance, beginning of period $ 82 $ 3 $ 85 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (6 ) — (6 ) AULC balance, end of period $ 76 $ 3 $ 79 ACL balance, end of period $ 550 $ 204 $ 754 Nine-month period ended September 30, 2017: ALLL balance, beginning of period $ 451 $ 187 $ 638 Loan charge-offs (58 ) (134 ) (192 ) Recoveries of loans previously charged-off 34 40 74 Provision for loan and lease losses 47 108 155 ALLL balance, end of period $ 474 $ 201 $ 675 AULC balance, beginning of period $ 87 $ 11 $ 98 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (11 ) (8 ) (19 ) AULC balance, end of period $ 76 $ 3 $ 79 ACL balance, end of period $ 550 $ 204 $ 754 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 commercial 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 September 30, 2018 and December 31, 2017 . September 30, 2018 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 27,407 $ 678 $ 1,104 $ 7 $ 29,196 Commercial real estate 6,766 189 117 1 7,073 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,233 $ 4,503 $ 1,350 $ 289 $ 12,375 Home equity 6,173 2,963 650 62 9,848 Residential mortgage 6,841 2,783 622 134 10,380 RV and marine finance 2,007 966 101 78 3,152 Other consumer 471 612 124 58 1,265 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 September 30, 2018 and December 31, 2017 . (dollar amounts in millions) Commercial Consumer Total ALLL at September 30, 2018 Portion of ALLL balance: Attributable to loans individually evaluated for impairment $ 46 $ 10 $ 56 Attributable to loans collectively evaluated for impairment 497 208 705 Total ALLL balance $ 543 $ 218 $ 761 Loan and Lease Ending Balances at September 30, 2018 (1) Portion of loan and lease ending balance: Individually evaluated for impairment $ 623 $ 598 $ 1,221 Collectively evaluated for impairment 35,646 36,422 72,068 Total loans and leases evaluated for impairment $ 36,269 $ 37,020 $ 73,289 (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) September 30, 2018 Three Months Ended Nine 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 $ 252 $ 289 $ — $ 264 $ 5 $ 264 $ 16 Commercial real estate 33 44 — 36 2 49 6 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 291 318 43 284 3 285 9 Commercial real estate 47 52 3 49 1 48 2 Automobile 39 43 2 38 1 37 2 Home equity 325 370 6 326 3 330 11 Residential mortgage 286 322 4 290 3 299 8 RV and marine finance 3 3 — 2 — 2 — Other consumer 8 8 3 9 — 8 — Total Commercial and industrial (3) 543 607 43 548 8 549 25 Commercial real estate (4) 80 96 3 85 3 97 8 Automobile (2) 39 43 2 38 1 37 2 Home equity (5) 325 370 6 326 3 330 11 Residential mortgage (5) 286 322 4 290 3 299 8 RV and marine finance (2) 3 3 — 2 — 2 — Other consumer (2) 8 8 3 9 — 8 — December 31, 2017 Three Months Ended Nine 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 $ — $ 295 $ 5 $ 228 $ 7 Commercial real estate 56 81 — 71 2 80 6 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 257 280 29 223 2 334 13 Commercial real estate 51 51 3 41 — 54 1 Automobile 36 40 2 33 — 32 2 Home equity 334 385 14 331 4 327 12 Residential mortgage 308 338 4 320 3 329 9 RV and marine finance 2 3 — 1 — 1 — Other consumer 8 8 2 7 — 7 — Total Commercial and industrial (3) 541 591 29 518 7 562 20 Commercial real estate (4) 107 132 3 112 2 134 7 Automobile (2) 36 40 2 33 — 32 2 Home equity (5) 334 385 14 331 4 327 12 Residential mortgage (5) 308 338 4 320 3 329 9 RV and marine finance (2) 2 3 — 1 — 1 — Other consumer (2) 8 8 2 7 — 7 — (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 September 30, 2018 and December 31, 2017 , C&I loans of $408 million and $382 million , respectively, were considered impaired due to their status as a TDR. (4) At September 30, 2018 and December 31, 2017 , CRE loans of $68 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 nine-month periods ended September 30, 2018 and 2017 . New Troubled Debt Restructurings (1) Three Months Ended September 30, 2018 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 131 $ — $ 35 $ — $ — $ 35 $ — Commercial real estate 9 — 5 — — 5 — Automobile 848 — 4 3 — 7 — Home equity 159 — 8 3 — 11 (1 ) Residential mortgage 76 — 8 1 — 9 — RV and marine finance 40 — — — — — — Other consumer 386 2 — — — 2 — Total new TDRs 1,649 $ 2 $ 60 $ 7 $ — $ 69 $ (1 ) Three Months Ended September 30, 2017 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 277 $ 1 $ 138 $ — $ — $ 139 $ (1 ) Commercial real estate 28 — 18 — — 18 — Automobile 797 — 4 3 — 7 — Home equity 247 — 12 3 — 15 — Residential mortgage 123 — 11 2 — 13 — RV and marine finance 32 — — 1 — 1 — Other consumer 699 — 2 — — 2 — Total new TDRs 2,203 $ 1 $ 185 $ 9 $ — $ 195 $ (1 ) (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 (1) Nine Months Ended September 30, 2018 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 641 $ — $ 302 $ — $ — $ 302 $ (7 ) Commercial real estate 95 — 79 — — 79 (1 ) Automobile 2,088 — 11 6 — 17 — Home equity 472 — 21 8 — 29 (2 ) Residential mortgage 278 — 29 2 — 31 (1 ) RV and marine finance 99 — — 1 — 1 — Other consumer 1,320 6 — — — 6 — Total new TDRs 4,993 $ 6 $ 442 $ 17 $ — $ 465 $ (11 ) Nine Months Ended September 30, 2017 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 747 $ 1 $ 419 $ — $ — $ 420 $ (9 ) Commercial real estate 71 — 74 — — 74 (1 ) Automobile 2,065 — 11 6 — 17 1 Home equity 739 1 26 9 4 40 (1 ) Residential mortgage 375 — 31 6 3 40 (1 ) RV and marine finance 105 — 1 1 — 2 — Other consumer 707 — 4 — — 4 — Total new TDRs 4,809 $ 2 $ 566 $ 22 $ 7 $ 597 $ (11 ) (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 September 30, 2018 and December 31, 2017 , these borrowings and advances are secured by $44.1 billion and $31.7 billion of loans and securities, respectively.

AVAILABLE-FOR-SALE SECURITIES

AVAILABLE-FOR-SALE SECURITIES	9 Months Ended
AVAILABLE-FOR-SALE SECURITIES	Sep. 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 September 30, 2018 and December 31, 2017 were: September 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 $ 5 $ 5 $ 5 $ 5 Total U.S. Treasury 5 5 5 5 Federal agencies: Residential CMO: After 1 year through 5 years — — 1 1 After 5 years through 10 years 41 40 90 89 After 10 years 7,266 6,900 6,570 6,394 Total Residential CMO 7,307 6,940 6,661 6,484 Residential MBS: After 1 year through 5 years 3 3 6 6 After 5 years through 10 years 30 29 7 8 After 10 years 613 588 1,358 1,353 Total Residential MBS 646 620 1,371 1,367 Commercial MBS: After 1 year through 5 years 68 65 23 22 After 5 years through 10 years 8 8 151 148 After 10 years 1,707 1,630 2,365 2,317 Total Commercial MBS 1,783 1,703 2,539 2,487 Other agencies: 1 year or less 1 1 2 2 After 1 year through 5 years 10 10 9 9 After 5 years through 10 years 151 146 58 59 Total other agencies 162 157 69 70 Total U.S. Treasury, Federal agency, and other agency securities 9,903 9,425 10,645 10,413 Municipal securities: 1 year or less 211 208 103 103 After 1 year through 5 years 1,156 1,143 1,140 1,134 After 5 years through 10 years 1,714 1,686 1,709 1,704 After 10 years 833 811 940 937 Total municipal securities 3,914 3,848 3,892 3,878 Asset-backed securities: After 1 year through 5 years 40 39 80 80 After 5 years through 10 years 41 41 53 54 After 10 years 291 283 349 333 Total asset-backed securities 372 363 482 467 Corporate debt: 1 year or less 1 1 — — After 1 year through 5 years 74 74 73 74 After 5 years through 10 years 11 12 20 21 After 10 years — — 13 14 Total corporate debt 86 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 $ 14,279 $ 13,727 $ 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 September 30, 2018 and December 31, 2017 : Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value September 30, 2018 U.S. Treasury $ 5 $ — $ — $ 5 Federal agencies: Residential CMO 7,307 — (367 ) 6,940 Residential MBS 646 — (26 ) 620 Commercial MBS 1,783 — (80 ) 1,703 Other agencies 162 — (5 ) 157 Total U.S. Treasury, Federal agency and other agency securities 9,903 — (478 ) 9,425 Municipal securities 3,914 11 (77 ) 3,848 Asset-backed securities 372 — (9 ) 363 Corporate debt 86 1 — 87 Other securities/Sovereign debt 4 — — 4 Total available-for-sale securities $ 14,279 $ 12 $ (564 ) $ 13,727 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 September 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 September 30, 2018 Federal agencies: Residential CMO $ 2,286 $ (77 ) $ 4,632 $ (290 ) $ 6,918 $ (367 ) Residential MBS 542 (23 ) 70 (3 ) 612 (26 ) Commercial MBS 109 (4 ) 1,594 (76 ) 1,703 (80 ) Other agencies 80 (2 ) 72 (3 ) 152 (5 ) Total Federal Agency and other agency securities 3,017 (106 ) 6,368 (372 ) 9,385 (478 ) Municipal securities 1,846 (39 ) 1,278 (38 ) 3,124 (77 ) Asset-backed securities 157 (3 ) 146 (6 ) 303 (9 ) Corporate debt 65 — — — 65 — Other securities/Sovereign debt — — — — — — Total temporarily impaired securities $ 5,085 $ (148 ) $ 7,792 $ (416 ) $ 12,877 $ (564 ) 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 September 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 $4.6 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 September 30, 2018 or December 31, 2017 . The following table is a summary of realized securities gains and losses for the three-month and nine-month periods ended September 30, 2018 and 2017 , respectively. Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Gross gains on sales of securities $ — $ 4 $ 6 $ 8 Gross losses on sales of securities (2 ) (4 ) (8 ) (4 ) Net (loss) gain on sales of securities $ (2 ) $ — $ (2 ) $ 4 OTTI recognized in earnings — — — (4 ) Net securities losses $ (2 ) $ — $ (2 ) $ — 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 September 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	9 Months Ended
HELD-TO-MATURITY SECURITIES	Sep. 30, 2018
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [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 September 30, 2018 and December 31, 2017 . September 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 36 35 — — After 10 years 2,167 2,073 3,714 3,657 Total Residential CMO 2,203 2,108 3,714 3,657 Residential MBS: After 5 years through 10 years — — 28 28 After 10 years 1,624 1,555 1,021 1,016 Total Residential MBS 1,624 1,555 1,049 1,044 Commercial MBS: After 1 year through 5 years — — 38 37 After 5 years through 10 years 130 126 1 1 After 10 years 4,141 3,968 3,752 3,698 Total Commercial MBS 4,271 4,094 3,791 3,736 Other agencies: After 1 year through 5 years 12 12 7 8 After 5 years through 10 years 204 197 362 360 After 10 years 146 141 163 161 Total other agencies 362 350 532 529 Total Federal agencies and other agencies 8,460 8,107 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 $ 8,465 $ 8,112 $ 9,091 $ 8,971 The following table provides amortized cost, gross unrealized gains and losses, and fair value by investment category at September 30, 2018 and December 31, 2017 . Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value September 30, 2018 Federal agencies: Residential CMO $ 2,203 $ — $ (95 ) $ 2,108 Residential MBS 1,624 — (69 ) 1,555 Commercial MBS 4,271 — (177 ) 4,094 Other agencies 362 — (12 ) 350 Total Federal agencies and other agencies 8,460 — (353 ) 8,107 Municipal securities 5 — — 5 Total held-to-maturity securities $ 8,465 $ — $ (353 ) $ 8,112 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 September 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 September 30, 2018 Federal agencies: Residential CMO $ 557 $ (21 ) $ 1,551 $ (74 ) $ 2,108 $ (95 ) Residential MBS 807 (33 ) 748 (36 ) 1,555 (69 ) Commercial MBS 410 (15 ) 3,683 (162 ) 4,093 (177 ) Other agencies 192 (6 ) 138 (6 ) 330 (12 ) Total Federal agencies and other agencies 1,966 (75 ) 6,120 (278 ) 8,086 (353 ) Municipal securities — — 4 — 4 — Total temporarily impaired securities $ 1,966 $ (75 ) $ 6,124 $ (278 ) $ 8,090 $ (353 ) 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 September 30, 2018 , Huntington has evaluated held-to-maturity securities with gross unrealized losses for impairment and concluded no OTTI is required.

OTHER SECURITIES

OTHER SECURITIES	9 Months Ended
OTHER SECURITIES	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
OTHER SECURITIES	OTHER SECURITIES September 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 248 248 287 287 Federal Reserve Bank stock 295 295 294 294 Other securities, at fair value Mutual funds 20 20 18 18 Marketable equity securities 1 2 1 1 Total other securities $ 564 $ 565 $ 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	9 Months Ended
LOAN SALES AND SECURITIZATIONS	Sep. 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 nine-month periods ended September 30, 2018 and 2017 : Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Residential mortgage loans sold with servicing retained $ 1,047 $ 1,179 $ 2,787 $ 2,824 Pretax gains resulting from above loan sales (1) 24 27 64 66 (1) Recorded in mortgage banking income. The following table summarizes the changes in MSRs recorded using the amortization method for the three-month and nine-month periods ended September 30, 2018 and 2017 : Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 204 $ 176 $ 191 $ 172 New servicing assets created 12 13 32 31 Impairment recovery (charge) — 1 7 — Amortization (8 ) (7 ) (22 ) (20 ) Carrying value, end of period $ 208 $ 183 $ 208 $ 183 Fair value, end of period $ 222 $ 184 $ 222 $ 184 Weighted-average life (years) 7.1 7.0 7.1 7.0 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 September 30, 2018 , and December 31, 2017 follows: September 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) 8.10 % $ (5 ) $ (10 ) 8.30 % $ (5 ) $ (10 ) Spread over forward interest rate swap rates 941 bps (7 ) (14 ) 1,049 bps (7 ) (13 ) Additionally, at September 30, 2018 and 2017 , Huntington held MSRs recorded using the fair value method of $11 million and $12 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 September 30, 2018 and 2017 , respectively. For the nine-month periods ended September 30, 2018 and 2017 , total servicing, late and other ancillary fees included in mortgage banking income were $44 million and $42 million . The unpaid principal balance of residential mortgage loans serviced for third parties was $20.6 billion and $19.8 billion at September 30, 2018 and December 31, 2017 , respectively.

LONG-TERM DEBT

LONG-TERM DEBT	9 Months Ended
LONG-TERM DEBT	Sep. 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. 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. In August 2018, the Bank issued $750 million of senior notes at 99.780% of face value. The senior notes mature on October 6, 2023 and have a fixed coupon rate of 3.550% . The senior notes may be redeemed one month prior to the maturity date at 100% of principal plus accrued and unpaid interest.

OTHER COMPREHENSIVE INCOME

OTHER COMPREHENSIVE INCOME	9 Months Ended
OTHER COMPREHENSIVE INCOME	Sep. 30, 2018
Equity [Abstract]
OTHER COMPREHENSIVE INCOME	OTHER COMPREHENSIVE INCOME The components of Huntington's OCI for the three-month and nine-month periods ended September 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 (82 ) 18 (64 ) Less: Reclassification adjustment for net losses (gains) included in net income 3 (1 ) 2 Net change in unrealized holding gains (losses) on available-for-sale debt securities (79 ) 17 (62 ) Net change in pension and other post-retirement obligations 2 (1 ) 1 Total other comprehensive income (loss) $ (77 ) $ 16 $ (61 ) 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 (42 ) 15 (27 ) Less: Reclassification adjustment for net losses (gains) included in net income 9 (4 ) 5 Net change in unrealized holding gains (losses) on available-for-sale debt securities (33 ) 11 (22 ) Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period 2 — 2 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 — 2 Net change in pension and other post-retirement obligations 2 (1 ) 1 Total other comprehensive income (loss) $ (29 ) $ 10 $ (19 ) Nine 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 (359 ) 78 (281 ) Less: Reclassification adjustment for net losses (gains) included in net income 21 (4 ) 17 Net change in unrealized holding gains (losses) on available-for-sale debt securities (338 ) 74 (264 ) Net change in pension and other post-retirement obligations 4 (1 ) 3 Total other comprehensive income (loss) $ (334 ) $ 73 $ (261 ) Nine 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 20 (7 ) 13 Less: Reclassification adjustment for net losses (gains) included in net income 19 (7 ) 12 Net change in unrealized holding gains (losses) on available-for-sale debt securities 42 (15 ) 27 Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period 2 — 2 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 3 (1 ) 2 Net change in pension and other post-retirement obligations 3 (1 ) 2 Total other comprehensive income (loss) $ 48 $ (17 ) $ 31 Activity in accumulated OCI for the nine -month periods ended September 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, 2017 $ (278 ) $ — $ (250 ) $ (528 ) Cumulative-effect adjustments (ASU 2016-01) (1 ) — — (1 ) Other comprehensive income before reclassifications (281 ) — — (281 ) Amounts reclassified from accumulated OCI to earnings 17 — 3 20 Period change (264 ) — 3 (261 ) September 30, 2018 $ (543 ) $ — $ (247 ) $ (790 ) December 31, 2016 $ (193 ) $ (3 ) $ (205 ) $ (401 ) Other comprehensive income before reclassifications 15 2 — 17 Amounts reclassified from accumulated OCI to earnings 12 — 2 14 Period change 27 2 2 31 September 30, 2017 $ (166 ) $ (1 ) $ (203 ) $ (370 ) (1) AOCI amounts at September 30, 2018 , December 31, 2017 and September 30, 2017 include $141 million , $95 million and $97 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 nine-month periods ended September 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) September 30, 2018 September 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (3 ) $ (1 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities — (8 ) Noninterest income - net gains (losses) on sale of securities OTTI recorded — — Noninterest income - net gains (losses) on sale of securities Total before tax (3 ) (9 ) Tax (expense) benefit 1 4 Net of tax $ (2 ) $ (5 ) Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (2 ) $ (1 ) Noninterest income / expense (1) Net periodic benefit costs — (1 ) Noninterest income / expense (1) Total before tax (2 ) (2 ) Tax (expense) benefit 1 1 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 Nine Months Ended (dollar amounts in millions) September 30, 2018 September 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (9 ) $ (7 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities (12 ) (8 ) Noninterest income - net gains (losses) on sale of securities OTTI recorded — (4 ) Noninterest income - net gains (losses) on sale of securities Total before tax (21 ) (19 ) Tax (expense) benefit 4 7 Net of tax $ (17 ) $ (12 ) Gains (losses) on cash flow hedging relationships: Interest rate contracts $ — $ (1 ) Interest income - loans and leases Interest rate contracts — — Noninterest income - other income Total before tax — (1 ) Tax (expense) benefit — 1 Net of tax $ — $ — Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (6 ) $ (4 ) Noninterest income / expense (1) Net periodic benefit costs 2 1 Noninterest income / expense (1) Total before tax (4 ) (3 ) Tax (expense) benefit 1 1 Net of tax $ (3 ) $ (2 ) (1) The activity for 2018 and 2017 is recorded in Noninterest Income - other noninterest income and Noninterest Expense - personnel costs, respectively, on the Condensed Consolidated Statements of Income.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	9 Months Ended
SHAREHOLDERS' EQUITY	Sep. 30, 2018
Equity [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY The following is a summary of Huntington's non-cumulative perpetual preferred stock outstanding as of September 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, 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 prior approval of the FRB.

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
EARNINGS PER SHARE	Sep. 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 nine -month periods ended September 30, 2018 and 2017 was as follows: Three Months Ended Nine Months Ended (dollar amounts in millions, share amounts in thousands) 2018 2017 2018 2017 Basic earnings per common share: Net income $ 378 $ 275 $ 1,059 $ 754 Preferred stock dividends (18 ) (19 ) (51 ) (57 ) Net income available to common shareholders $ 360 $ 256 $ 1,008 $ 697 Average common shares issued and outstanding 1,084,536 1,086,038 1,090,570 1,087,115 Basic earnings per common share $ 0.33 $ 0.24 $ 0.92 $ 0.64 Diluted earnings per common share: Net income available to common shareholders $ 360 $ 256 $ 1,008 $ 697 Effect of assumed preferred stock conversion — — — — Net income applicable to diluted earnings per share $ 360 $ 256 $ 1,008 $ 697 Average common shares issued and outstanding 1,084,536 1,086,038 1,090,570 1,087,115 Dilutive potential common shares: Stock options and restricted stock units and awards 15,655 17,079 17,105 17,515 Shares held in deferred compensation plans 3,549 3,228 3,416 3,096 Dilutive impact of Preferred Stock — — 5,887 — Other — 146 — 152 Dilutive potential common shares 19,204 20,453 26,408 20,763 Total diluted average common shares issued and outstanding 1,103,740 1,106,491 1,116,978 1,107,878 Diluted earnings per common share $ 0.33 $ 0.23 $ 0.90 $ 0.63 There were approximately 1.6 million and 1.5 million of options to purchase shares of common stock outstanding for the three-month periods ended September 30, 2018 and 2017 , respectively. There were approximately 2.0 million and 0.9 million of options to purchase shares of common stock outstanding for the nine-month periods ended September 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)	9 Months Ended
NON-INTEREST INCOME (Notes)	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition, Policy [Policy Text Block]	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 has been assessed as not material. 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.
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 September 30, 2018 Nine Months Ended September 30, 2018 Noninterest income Noninterest income from contracts with customers $ 223 $ 654 Noninterest income within the scope of other GAAP topics 119 338 Total noninterest income $ 342 $ 992 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 has been assessed as not material. 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 September 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 $ 75 $ 16 $ 1 $ 1 $ — $ 93 Cards and payment processing income 50 3 — — — 53 Trust and investment management services 7 1 — 34 — 42 Insurance income 8 1 — 10 — 19 Other income 10 2 1 2 1 16 Net revenue from contracts with customers $ 150 $ 23 $ 2 $ 47 $ 1 $ 223 Noninterest income within the scope of other GAAP topics 42 56 — — 21 119 Total noninterest income $ 192 $ 79 $ 2 $ 47 $ 22 $ 342 Nine Months Ended September 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 $ 215 $ 48 $ 4 $ 3 $ — $ 270 Cards and payment processing income 146 8 — — — 154 Trust and investment management services 19 3 — 106 — 128 Insurance income 26 3 — 31 1 61 Other Income 30 3 2 4 2 41 Net revenue from contracts with customers $ 436 $ 65 $ 6 $ 144 $ 3 $ 654 Noninterest income within the scope of other GAAP topics 117 163 2 1 55 338 Total noninterest income $ 553 $ 228 $ 8 $ 145 $ 58 $ 992 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 September 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 September 30, 2018 was determined to be immaterial.

BENEFIT PLANS

BENEFIT PLANS	9 Months Ended
BENEFIT PLANS	Sep. 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 September 30, Three Months Ended September 30, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ — $ — $ — $ — Interest cost 9 8 — — Expected return on plan assets (12 ) (13 ) — — Amortization of prior service cost — — (1 ) — Amortization of loss 2 1 — — Settlements 1 4 — — Net periodic (benefit) cost $ — $ — $ (1 ) $ — Pension Benefits (1) Post-Retirement Benefits (1) Nine Months Ended September 30, Nine Months Ended September 30, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ 2 $ 2 $ — $ — Interest cost 23 22 — — Expected return on plan assets (36 ) (41 ) — — Amortization of prior service cost — — (2 ) (1 ) Amortization of loss 6 5 — — Settlements 6 10 — — Net periodic (benefit) cost $ 1 $ (2 ) $ (2 ) $ (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, in 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 third quarter 2018 and 2017 was $7 million and $5 million , respectively. For the nine-month period ended September 30, 2018 and 2017 , expense related to the defined contribution plans was $35 million and $26 million , respectively.

FAIR VALUES OF ASSETS AND LIABI

FAIR VALUES OF ASSETS AND LIABILITIES	9 Months Ended
FAIR VALUES OF ASSETS AND LIABILITIES	Sep. 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 nine-month periods ended September 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 September 30, 2018 and December 31, 2017 are summarized below: Fair Value Measurements at Reporting Date Using Netting Adjustments (1) September 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Municipal securities $ — $ 5 $ — $ — $ 5 Other securities 77 1 — — 78 77 6 — — 83 Available-for-sale securities: U.S. Treasury securities 5 — — — 5 Residential CMOs — 6,940 — — 6,940 Residential MBS — 620 — — 620 Commercial MBS — 1,703 — — 1,703 Other agencies — 157 — — 157 Municipal securities — 571 3,277 — 3,848 Asset-backed securities — 363 — — 363 Corporate debt — 87 — — 87 Other securities/sovereign debt — 4 — — 4 5 10,445 3,277 — 13,727 Other securities 22 — — — 22 Loans held for sale — 727 — — 727 Loans held for investment — 49 32 — 81 MSRs — — 11 — 11 Derivative assets — 493 5 (318 ) 180 Liabilities Derivative liabilities — 437 4 (221 ) 220 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 nine-month periods ended September 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 $ 11 $ 1 $ 3,178 $ 34 Transfers out of Level 3 (1) — (12 ) — — Total gains/losses for the period: Included in earnings — 9 (1 ) — Included in OCI — — — — Purchases/originations — — 260 — Sales — — — — Repayments — — — (2 ) Settlements — 3 (160 ) — Closing balance $ 11 $ 1 $ 3,277 $ 32 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ (3 ) $ — $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Opening balance $ 13 $ 3 $ 2,872 $ 43 $ 44 Transfers out of Level 3 (1) — (1 ) — — — Total gains/losses for the period: Included in earnings (1 ) 1 (1 ) (2 ) — Included in OCI — — (34 ) 5 — Purchases/originations — — 167 — — Sales — — — (22 ) — Repayments — — — — (4 ) Settlements — — (46 ) — — Closing balance $ 12 $ 3 $ 2,958 $ 24 $ 40 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (1 ) $ 1 $ — $ — $ — (1) Transfers out of Level 3 represent the settlement value of the derivative instruments (i.e. interest rate lock agreements) that is transferred to loans held for sale, which is classified as Level 2. 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 out of Level 3 (1) — (26 ) — — — Total gains/losses for the period: Included in earnings — 25 (3 ) (2 ) — Included in OCI — — (37 ) 11 — Purchases/originations — — 539 — — Sales — — — (33 ) — Repayments — — — — (6 ) Settlements — 3 (389 ) — — Closing balance $ 11 $ 1 $ 3,277 $ — $ 32 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ (1 ) $ — $ — $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset- backed securities Loans held for investment Opening balance $ 14 $ (2 ) $ 2,798 $ 76 $ 48 Transfers out of Level 3 (1) — (4 ) — — — Total gains/losses for the period: Included in earnings (2 ) 9 (4 ) (5 ) 1 Included in OCI — — (1 ) 13 — Purchases/originations — — 414 — — Sales — — — (59 ) — Repayments — — — — (9 ) Settlements — — (249 ) (1 ) — Closing balance $ 12 $ 3 $ 2,958 $ 24 $ 40 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (2 ) $ 9 $ — $ (4 ) $ — (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 nine-month periods ended September 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 $ — $ 9 $ — $ — Other expense — — (1 ) — Total $ — $ 9 $ (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 $ (1 ) $ 1 $ — $ — $ — Securities gains (losses) — — — (2 ) — Interest and fee income — — (1 ) — — Total $ (1 ) $ 1 $ (1 ) $ (2 ) $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ — $ 25 $ — $ — $ — Securities gains (losses) — — — (2 ) — Other expense — — (3 ) — — Total $ — $ 25 $ (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 $ (2 ) $ 9 $ — $ — $ — Securities gains (losses) — — — (5 ) — Interest and fee income — — (4 ) — — Noninterest income — — — — 1 Total $ (2 ) $ 9 $ (4 ) $ (5 ) $ 1 Assets and liabilities under the fair value option The following tables present the fair value and aggregate principal balance of certain assets and liabilities under the fair value option: September 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 $ 727 $ 713 $ 14 $ — $ — $ — Loans held for investment 81 88 (7 ) 6 7 (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 nine-month periods ended September 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 September 30, Nine Months Ended September 30, Assets 2018 2017 2018 2017 Loans held for sale $ (4 ) $ (2 ) $ (1 ) $ 12 Loans held for investment — — — 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 nine months ended September 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 53 — — 53 1 Other real estate owned 27 — — 27 (1 ) 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. Periodically, 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 September 30, 2018 and December 31, 2017 : Quantitative Information about Level 3 Fair Value Measurements at September 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% - 54% (8%) Spread over forward interest rate 5% - 11% (8%) Derivative assets 5 Consensus Pricing Net market price -4%-8%(1%) Estimated Pull through % 3% - 100% (91%) Derivative liabilities 4 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 6/30/2020 Municipal securities 3,277 Discounted cash flow Discount rate 3% - 4% (3%) Cumulative default 0% - 64% (4%) Loss given default 5% - 90% (25%) Loans held for investment 32 Discounted cash flow Discount rate 7% (7%) Constant prepayment rate 9% (9%) Measured at fair value on a nonrecurring basis: Impaired loans 53 Appraisal value NA NA Other real estate owned 27 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 September 30, 2018 and December 31, 2017 : September 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 1,342 — — 1,342 1,342 Trading account securities — — 83 83 83 Available-for-sale securities — — 13,727 13,727 13,727 Held-to-maturity securities 8,465 — — 8,465 8,112 Other securities 543 — 22 565 565 Loans held for sale — 65 727 792 795 Net loans and direct financing leases (1) 72,528 — 81 72,609 71,918 Derivatives — — 180 180 180 Financial Liabilities Deposits 81,689 — — 81,689 81,631 Short-term borrowings 1,348 — — 1,348 1,348 Long-term debt 9,385 — — 9,385 9,523 Derivatives — — 220 220 220 (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 September 30, 2018 and December 31, 2017 : Estimated Fair Value Measurements at Reporting Date Using September 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 77 $ 6 $ — $ 83 Available-for-sale securities 5 10,445 3,277 13,727 Held-to-maturity securities — 8,112 — 8,112 Other securities 22 — — 22 Loans held for sale — 727 68 795 Net loans and direct financing leases — 49 71,869 71,918 Financial Liabilities Deposits — 74,423 7,208 81,631 Short-term borrowings 2 — 1,346 1,348 Long-term debt — 8,986 537 9,523 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	9 Months Ended
DERIVATIVE FINANCIAL INSTRUMENTS	Sep. 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 September 30, 2018 and December 31, 2017 . Amounts in the table below are presented gross without the impact of any net collateral arrangements. September 30, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Derivatives designated as Hedging Instruments Interest rate contracts $ 15 $ 65 $ 22 $ 121 Derivatives not designated as Hedging Instruments Interest rate contracts 294 198 187 100 Foreign exchange contracts 28 22 18 18 Commodities contracts 157 152 92 87 Equity contracts 4 4 3 5 Total Contracts $ 498 $ 441 $ 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 nine-month periods ended September 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 September 30, 2018 Nine Months Ended September 30, 2018 Interest rate contracts: Customer Capital markets fees $ 11 $ 30 Mortgage Banking Mortgage banking income 5 (3 ) Foreign exchange contracts Capital markets fees 6 18 Commodities contracts Capital markets fees 1 3 Equity contracts Other noninterest expense — 3 Total $ 23 $ 51 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 September 30, 2018 and December 31, 2017 , identified by the underlying interest rate-sensitive instruments. September 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 5,340 — 5,340 Total notional value at September 30, 2018 $ 5,715 $ 12 $ 5,727 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 September 30, 2018 and December 31, 2017 . September 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 1.5 $ — 2.20 % 2.16 % Liability conversion swaps Receive fixed—generic 5,715 2.5 (50 ) 2.08 2.26 Total swap portfolio at September 30, 2018 $ 5,727 2.5 $ (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 $(11) million and $3 million for the three-month periods ended September 30, 2018 , and 2017 , respectively, and $(25) million and $20 million for the nine -month periods ended September 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 recorded as a loss of $149 million , which is being amortized over the remaining life of the long-term debt using the effective yield method. Cash payments to counterparties resulting from termination of interest rate swaps are classified as operating activities in our unaudited condensed consolidated statements of cash flows. 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 nine-month periods ended September 30, 2018 and 2017 . Three Months Ended Nine 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) $ (2 ) $ (2 ) $ 22 $ (5 ) Change in fair value of hedged subordinated notes (1) 2 4 (22 ) 7 Change in fair value of interest rate swaps hedging other long-term debt (1) (9 ) (6 ) 33 (1 ) Change in fair value of hedged other long-term debt (1) 10 7 (27 ) (1 ) (1) Recognized in Interest expense—subordinated notes and other long-term debt in the Unaudited Condensed Consolidated Statements of Income. As of September 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) September 30, 2018 September 30, 2018 Long-term debt $ 5,637 $ (67 ) The cumulative amount of fair value hedging adjustments remaining for any hedged assets and liabilities for which hedge accounting has been discontinued is $(135) million at September 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 net asset position of these derivatives at September 30, 2018 and December 31, 2017 are $8 million and $7 million , respectively. 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 September 30, 2018 and December 31, 2017 , were $100 million and $88 million , respectively. The total notional values of derivative financial instruments used by Huntington on behalf of customers, including offsetting derivatives, were $25 billion and $22 billion at September 30, 2018 and December 31, 2017 , respectively. Huntington’s credit risk from interest rate swaps used for trading purposes was $115 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 September 30, 2018 , the combined fair value of the swap liabilities of $4 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 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 September 30, 2018 and December 31, 2017 , aggregate credit risk associated with these derivatives, net of collateral that has been pledged by the counterparty, was $17 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 September 30, 2018 , Huntington pledged $72 million of investment securities and cash collateral to counterparties, while other counterparties pledged $246 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 September 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 September 30, 2018 Derivatives $ 498 $ (318 ) $ 180 $ (2 ) $ (59 ) $ 119 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 September 30, 2018 Derivatives $ 441 $ (221 ) $ 220 $ — $ (15 ) $ 205 December 31, 2017 Derivatives 331 (245 ) 86 — (21 ) 65

VIEs

VIEs	9 Months Ended
VIEs	Sep. 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 September 30, 2018 , and December 31, 2017 : September 30, 2018 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 3 $ 1 $ 3 2015-1 Automobile Trust — — — Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 683 345 683 Other Investments 125 54 125 Total $ 825 $ 652 $ 811 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 Huntington transferred two automobile loans to trusts in two separate 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. 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 September 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 3.10 % (2) $ 70 $ 6 Huntington Capital II 3.02 (3) 32 3 Sky Financial Capital Trust III 3.80 (4) 72 2 Sky Financial Capital Trust IV 3.80 (4) 74 2 Camco Financial Trust 3.73 (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 September 30, 2018 , based on three-month LIBOR + 0.70% . (3) Variable effective rate at September 30, 2018 , based on three-month LIBOR + 0.625% . (4) Variable effective rate at September 30, 2018 , based on three-month LIBOR + 1.40% . (5) Variable effective rate at September 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 September 30, 2018 and December 31, 2017 . (dollar amounts in millions) September 30, December 31, Affordable housing tax credit investments $ 1,102 $ 996 Less: amortization (419 ) (360 ) Net affordable housing tax credit investments $ 683 $ 636 Unfunded commitments $ 345 $ 335 The following table presents other information relating to Huntington’s affordable housing tax credit investments for the three-month and nine-month periods ended September 30, 2018 and 2017 . Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Tax credits and other tax benefits recognized $ 24 $ 22 $ 70 $ 68 Proportional amortization method Tax credit amortization expense included in provision for income taxes 19 17 59 51 There were no impairment losses recognized during the three-month period ended September 30, 2018. Huntington recognized immaterial impairment losses for the three-month and nine-month periods ended September 30, 2017 , and for the nine-month period ended September 30, 2018. 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 Small Business Investment Companies, Historic Tax Credit Investments, certain equity method investments and other miscellaneous investments.

COMMITMENTS AND CONTINGENT LIAB

COMMITMENTS AND CONTINGENT LIABILITIES	9 Months Ended
COMMITMENTS AND CONTINGENT LIABILITIES	Sep. 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 September 30, 2018 and December 31, 2017 , were as follows: (dollar amounts in millions) September 30, December 31, Contract amount representing credit risk Commitments to extend credit: Commercial $ 16,594 $ 16,219 Consumer 14,798 13,384 Commercial real estate 1,182 1,366 Standby letters of credit 623 510 Commercial letters-of-credit 33 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 $10 million and $10 million at September 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 secure 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 September 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 September 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. Based on current knowledge, management does not believe that loss contingencies arising from pending matters will have a material adverse effect on the consolidated financial position of Huntington. Further, management believes that amounts 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.

SEGMENT REPORTING

SEGMENT REPORTING	9 Months Ended
SEGMENT REPORTING	Sep. 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 September 30, 2018 , December 31, 2017 , and September 30, 2017 , reported results by business segment. Three Months Ended September 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 431 $ 239 $ 101 $ 48 $ (17 ) $ 802 Provision (benefit) for credit losses 42 (1 ) 12 — — 53 Noninterest income 192 79 2 47 22 342 Noninterest expense 425 124 37 61 4 651 Provision (benefit) for income taxes 33 41 11 7 (30 ) 62 Net income (loss) $ 123 $ 154 $ 43 $ 27 $ 31 $ 378 2017 Net interest income $ 391 $ 224 $ 108 $ 43 $ (8 ) $ 758 Provision (benefit) for credit losses 24 — 20 — (1 ) 43 Noninterest income 189 67 3 46 25 330 Noninterest expense 416 117 39 58 50 680 Provision (benefit) for income taxes 49 61 18 11 (49 ) 90 Net income (loss) $ 91 $ 113 $ 34 $ 20 $ 17 $ 275 Nine Months Ended September 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 1,239 $ 688 $ 300 $ 139 $ (10 ) $ 2,356 Provision (benefit) for credit losses 101 38 36 — — 175 Noninterest income 553 228 8 145 58 992 Noninterest expense 1,266 373 110 184 3 1,936 Provision (benefit) for income taxes 89 106 34 21 (72 ) 178 Net income (loss) $ 336 $ 399 $ 128 $ 79 $ 117 $ 1,059 2017 Net interest income $ 1,151 $ 675 $ 318 $ 126 $ (37 ) $ 2,233 Provision (benefit) for credit losses 75 15 45 1 — 136 Noninterest income 544 201 11 141 70 967 Noninterest expense 1,242 353 113 182 192 2,082 Provision (benefit) for income taxes 132 178 60 29 (171 ) 228 Net income (loss) $ 246 $ 330 $ 111 $ 55 $ 12 $ 754 Assets at Deposits at (dollar amounts in millions) September 30, December 31, September 30, December 31, Consumer & Business Banking $ 27,362 $ 26,220 $ 49,434 $ 45,643 Commercial Banking 33,759 32,118 22,288 21,235 Vehicle Finance 18,895 17,865 348 358 RBHPCG 6,374 5,821 5,783 6,057 Treasury / Other 19,262 22,161 3,836 3,748 Total $ 105,652 $ 104,185 $ 81,689 $ 77,041

ACCOUNTING STANDARDS UPDATE (Po

ACCOUNTING STANDARDS UPDATE (Policies)	9 Months Ended
ACCOUNTING STANDARDS UPDATE (Policies)	Sep. 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 Note 12 for further detail impact on adoption. ASU 2016-01 - Recognition and Measurement of Financial Assets and Financial Liabilities. Issued January 2016 - Makes targeted improvements related to certain aspects of recognition, measurement, presentation and disclosures for financial instruments 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 on January 1, 2018 using the modified retrospective approach. - Amendments were applied as a cumulative-effect adjustment to the balance sheet as of January 1, 2018. - 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 from the service cost component in the income statement. - 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 the 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. ASU 2018-15 - Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. Issued August 2018 - Aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software as well as with hosting arrangements that include an internal-use software license. - Requires the entity to expense the capitalized implementation costs of a hosting arrangement over the term of the hosting arrangement. - Requires the entity to present the expense related to implementation costs in the same statement of income line and statement of cash flows line where the fees for the service contract is recognized for respective statements. - Effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years with early adoption permitted. - Huntington early adopted the guidance effective 3Q 2018. The update did not have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements as the guidance was consistent with Huntington's existing accounting treatment for such arrangements. 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 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. - Management expects to elect certain practical expedients offered by the FASB, including adopting the standard as of the effective date, and foregoing the restatement of comparative periods. Management also expects to exclude short-term leases from the recognition of right-of-use asset and lease liabilities. Additionally, Huntington will elect the transition relief allowed by FASB in foregoing the reassessment of the following: whether any existing contracts are or contain leases, the classification of existing leases, and the determination of initial direct costs for existing leases. - Huntington expects to recognize right-of-use assets and lease liabilities of less than 1% of total assets, representing substantially all of its operating lease commitments. This estimate is based, primarily, on the present value of unpaid future minimum lease payments. Additionally, that amount may be impacted by assumptions around renewals and/or extensions, actual renewals and extensions before the effective date, the identification of embedded and other leases, and the interest rate used to discount those future lease obligations. 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 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 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. ASU 2018-13 - Fair Value Measurement (Topic 820). Issued August 2018 - Modifies the disclosure requirements on fair value measurements. - Removes disclosures for transfers between Level 1 and Level 2, the policy for timing of transfers between levels, and the valuation processes for Level 3 fair value measurements. - Clarifies that the information about uncertainty in measurement in uncertainty disclosure should be as of the reporting date. - Adds disclosures related to (a) changes in unrealized gains/losses in OCI for Level 3 fair value measurements for assets held at the end of the reporting period, and (b) the process of calculating weighted average for significant unobservable inputs used to develop Level 3 fair value measurements. - Effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years with early adoption permitted. - The amendment is not expected to have a significant impact on Huntington's Unaudited Condensed Consolidated Financial Statements. ASU 2018-14 - Compensation - Retirement Benefits - Defined Benefit Plans. Issued August 2018 - Modifies the disclosure requirements for defined benefit pension plans. - Removes disclosures pertaining to (a) the amounts of AOCI expected to be recognized as pension costs over the next fiscal year, (b) the amount and timing of plan assets expected to be returned to the employer, and (c) the effect of one-percentage-point change in the assumed health care trends on (i) service and interest cost and (ii) postretirement health care benefit obligation. - Adds a new disclosure requiring an explanation of the reasons for significant gains and losses related to changes in the benefit obligation for the period. - Effective retrospectively for fiscal years beginning after December 15, 2020 and interim periods within those fiscal years with early adoption permitted. - The amendment is not expected to have significant impact on the 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 has been assessed as not material. 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 _2

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES (Tables)	9 Months Ended
LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES (Tables)	Sep. 30, 2018
Receivables [Abstract]
Loan and Lease Portfolio	The following table provides a detailed listing of Huntington’s loan and lease portfolio at September 30, 2018 and December 31, 2017 . (dollar amounts in millions) September 30, 2018 December 31, 2017 Loans and leases: Commercial and industrial $ 29,196 $ 28,107 Commercial real estate 7,073 7,225 Automobile 12,375 12,100 Home equity 9,850 10,099 Residential mortgage 10,459 9,026 RV and marine finance 3,152 2,438 Other consumer 1,265 1,122 Loans and leases $ 73,370 $ 70,117 Allowance for loan and lease losses (761 ) (691 ) Net loans and leases $ 72,609 $ 69,426
NALs and Past Due Loans	The following table presents NALs by loan class at September 30, 2018 and December 31, 2017 . (dollar amounts in millions) September 30, December 31, Commercial and industrial $ 211 $ 161 Commercial real estate 19 29 Automobile 5 6 Home equity 67 68 Residential mortgage 67 84 RV and marine finance 1 1 Other consumer — — Total nonaccrual loans $ 370 $ 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 September 30, 2018 and December 31, 2017 : September 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 $ 48 $ 17 $ 58 $ 123 $ 29,073 $ — $ 29,196 $ 9 (2) Commercial real estate 6 1 7 14 7,059 — 7,073 — Automobile 77 16 8 101 12,274 — 12,375 7 Home equity 46 17 60 123 9,725 2 9,850 15 Residential mortgage 116 42 151 309 10,071 79 10,459 117 (3) RV and marine finance 9 2 2 13 3,139 — 3,152 1 Other consumer 13 6 5 24 1,241 — 1,265 5 Total loans and leases $ 315 $ 101 $ 291 $ 707 $ 72,582 $ 81 $ 73,370 $ 154 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 nine-month periods ended September 30, 2018 and 2017 . (dollar amounts in millions) Commercial Consumer Total Three-month period ended September 30, 2018: ALLL balance, beginning of period $ 531 $ 210 $ 741 Loan charge-offs (11 ) (47 ) (58 ) Recoveries of loans previously charged-off 15 14 29 Provision for loan and lease losses 8 41 49 ALLL balance, end of period $ 543 $ 218 $ 761 AULC balance, beginning of period $ 90 $ 3 $ 93 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 5 (1 ) 4 AULC balance, end of period $ 95 $ 2 $ 97 ACL balance, end of period $ 638 $ 220 $ 858 Nine-month period ended September 30, 2018: ALLL balance, beginning of period $ 482 $ 209 $ 691 Loan charge-offs (46 ) (138 ) (184 ) Recoveries of loans previously charged-off 45 44 89 Provision for loan and lease losses 62 103 165 ALLL balance, end of period $ 543 $ 218 $ 761 AULC balance, beginning of period $ 84 $ 3 $ 87 Provision (reduction in allowance) for unfunded loan commitments and letters of credit 11 (1 ) 10 AULC balance, end of period $ 95 $ 2 $ 97 ACL balance, end of period $ 638 $ 220 $ 858 (dollar amounts in millions) Commercial Consumer Total Three-month period ended September 30, 2017: ALLL balance, beginning of period $ 475 $ 193 $ 668 Loan charge-offs (19 ) (46 ) (65 ) Recoveries of loans previously charged-off 10 12 22 Provision for loan and lease losses 8 42 50 ALLL balance, end of period $ 474 $ 201 $ 675 AULC balance, beginning of period $ 82 $ 3 $ 85 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (6 ) — (6 ) AULC balance, end of period $ 76 $ 3 $ 79 ACL balance, end of period $ 550 $ 204 $ 754 Nine-month period ended September 30, 2017: ALLL balance, beginning of period $ 451 $ 187 $ 638 Loan charge-offs (58 ) (134 ) (192 ) Recoveries of loans previously charged-off 34 40 74 Provision for loan and lease losses 47 108 155 ALLL balance, end of period $ 474 $ 201 $ 675 AULC balance, beginning of period $ 87 $ 11 $ 98 Provision (reduction in allowance) for unfunded loan commitments and letters of credit (11 ) (8 ) (19 ) AULC balance, end of period $ 76 $ 3 $ 79 ACL balance, end of period $ 550 $ 204 $ 754
Loan and lease balances by credit quality indicator	The following table presents each loan and lease class by credit quality indicator at September 30, 2018 and December 31, 2017 . September 30, 2018 (dollar amounts in millions) Credit Risk Profile by UCS Classification Commercial Pass OLEM Substandard Doubtful Total Commercial and industrial $ 27,407 $ 678 $ 1,104 $ 7 $ 29,196 Commercial real estate 6,766 189 117 1 7,073 Credit Risk Profile by FICO Score (1), (2) Consumer 750+ 650-749 <650 Other (3) Total Automobile $ 6,233 $ 4,503 $ 1,350 $ 289 $ 12,375 Home equity 6,173 2,963 650 62 9,848 Residential mortgage 6,841 2,783 622 134 10,380 RV and marine finance 2,007 966 101 78 3,152 Other consumer 471 612 124 58 1,265 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 September 30, 2018 and December 31, 2017 . (dollar amounts in millions) Commercial Consumer Total ALLL at September 30, 2018 Portion of ALLL balance: Attributable to loans individually evaluated for impairment $ 46 $ 10 $ 56 Attributable to loans collectively evaluated for impairment 497 208 705 Total ALLL balance $ 543 $ 218 $ 761 Loan and Lease Ending Balances at September 30, 2018 (1) Portion of loan and lease ending balance: Individually evaluated for impairment $ 623 $ 598 $ 1,221 Collectively evaluated for impairment 35,646 36,422 72,068 Total loans and leases evaluated for impairment $ 36,269 $ 37,020 $ 73,289 (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) September 30, 2018 Three Months Ended Nine 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 $ 252 $ 289 $ — $ 264 $ 5 $ 264 $ 16 Commercial real estate 33 44 — 36 2 49 6 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 291 318 43 284 3 285 9 Commercial real estate 47 52 3 49 1 48 2 Automobile 39 43 2 38 1 37 2 Home equity 325 370 6 326 3 330 11 Residential mortgage 286 322 4 290 3 299 8 RV and marine finance 3 3 — 2 — 2 — Other consumer 8 8 3 9 — 8 — Total Commercial and industrial (3) 543 607 43 548 8 549 25 Commercial real estate (4) 80 96 3 85 3 97 8 Automobile (2) 39 43 2 38 1 37 2 Home equity (5) 325 370 6 326 3 330 11 Residential mortgage (5) 286 322 4 290 3 299 8 RV and marine finance (2) 3 3 — 2 — 2 — Other consumer (2) 8 8 3 9 — 8 — December 31, 2017 Three Months Ended Nine 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 $ — $ 295 $ 5 $ 228 $ 7 Commercial real estate 56 81 — 71 2 80 6 Automobile — — — — — — — Home equity — — — — — — — Residential mortgage — — — — — — — RV and marine finance — — — — — — — Other consumer — — — — — — — With an allowance recorded: Commercial and industrial 257 280 29 223 2 334 13 Commercial real estate 51 51 3 41 — 54 1 Automobile 36 40 2 33 — 32 2 Home equity 334 385 14 331 4 327 12 Residential mortgage 308 338 4 320 3 329 9 RV and marine finance 2 3 — 1 — 1 — Other consumer 8 8 2 7 — 7 — Total Commercial and industrial (3) 541 591 29 518 7 562 20 Commercial real estate (4) 107 132 3 112 2 134 7 Automobile (2) 36 40 2 33 — 32 2 Home equity (5) 334 385 14 331 4 327 12 Residential mortgage (5) 308 338 4 320 3 329 9 RV and marine finance (2) 2 3 — 1 — 1 — Other consumer (2) 8 8 2 7 — 7 — (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 September 30, 2018 and December 31, 2017 , C&I loans of $408 million and $382 million , respectively, were considered impaired due to their status as a TDR. (4) At September 30, 2018 and December 31, 2017 , CRE loans of $68 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 nine-month periods ended September 30, 2018 and 2017 . New Troubled Debt Restructurings (1) Three Months Ended September 30, 2018 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 131 $ — $ 35 $ — $ — $ 35 $ — Commercial real estate 9 — 5 — — 5 — Automobile 848 — 4 3 — 7 — Home equity 159 — 8 3 — 11 (1 ) Residential mortgage 76 — 8 1 — 9 — RV and marine finance 40 — — — — — — Other consumer 386 2 — — — 2 — Total new TDRs 1,649 $ 2 $ 60 $ 7 $ — $ 69 $ (1 ) Three Months Ended September 30, 2017 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 277 $ 1 $ 138 $ — $ — $ 139 $ (1 ) Commercial real estate 28 — 18 — — 18 — Automobile 797 — 4 3 — 7 — Home equity 247 — 12 3 — 15 — Residential mortgage 123 — 11 2 — 13 — RV and marine finance 32 — — 1 — 1 — Other consumer 699 — 2 — — 2 — Total new TDRs 2,203 $ 1 $ 185 $ 9 $ — $ 195 $ (1 ) (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 (1) Nine Months Ended September 30, 2018 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 641 $ — $ 302 $ — $ — $ 302 $ (7 ) Commercial real estate 95 — 79 — — 79 (1 ) Automobile 2,088 — 11 6 — 17 — Home equity 472 — 21 8 — 29 (2 ) Residential mortgage 278 — 29 2 — 31 (1 ) RV and marine finance 99 — — 1 — 1 — Other consumer 1,320 6 — — — 6 — Total new TDRs 4,993 $ 6 $ 442 $ 17 $ — $ 465 $ (11 ) Nine Months Ended September 30, 2017 Number of Post-modification Outstanding Recorded Investment (2) Financial effects of modification (3) (dollar amounts in millions) Interest rate reduction Amortization or maturity date change Chapter 7 bankruptcy Other Total Commercial and industrial 747 $ 1 $ 419 $ — $ — $ 420 $ (9 ) Commercial real estate 71 — 74 — — 74 (1 ) Automobile 2,065 — 11 6 — 17 1 Home equity 739 1 26 9 4 40 (1 ) Residential mortgage 375 — 31 6 3 40 (1 ) RV and marine finance 105 — 1 1 — 2 — Other consumer 707 — 4 — — 4 — Total new TDRs 4,809 $ 2 $ 566 $ 22 $ 7 $ 597 $ (11 ) (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)	9 Months Ended
AVAILABLE-FOR-SALE SECURITIES (Tables)	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Contractual maturities of investment securities	ontractual maturities of available-for-sale securities at September 30, 2018 and December 31, 2017 were: September 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 $ 5 $ 5 $ 5 $ 5 Total U.S. Treasury 5 5 5 5 Federal agencies: Residential CMO: After 1 year through 5 years — — 1 1 After 5 years through 10 years 41 40 90 89 After 10 years 7,266 6,900 6,570 6,394 Total Residential CMO 7,307 6,940 6,661 6,484 Residential MBS: After 1 year through 5 years 3 3 6 6 After 5 years through 10 years 30 29 7 8 After 10 years 613 588 1,358 1,353 Total Residential MBS 646 620 1,371 1,367 Commercial MBS: After 1 year through 5 years 68 65 23 22 After 5 years through 10 years 8 8 151 148 After 10 years 1,707 1,630 2,365 2,317 Total Commercial MBS 1,783 1,703 2,539 2,487 Other agencies: 1 year or less 1 1 2 2 After 1 year through 5 years 10 10 9 9 After 5 years through 10 years 151 146 58 59 Total other agencies 162 157 69 70 Total U.S. Treasury, Federal agency, and other agency securities 9,903 9,425 10,645 10,413 Municipal securities: 1 year or less 211 208 103 103 After 1 year through 5 years 1,156 1,143 1,140 1,134 After 5 years through 10 years 1,714 1,686 1,709 1,704 After 10 years 833 811 940 937 Total municipal securities 3,914 3,848 3,892 3,878 Asset-backed securities: After 1 year through 5 years 40 39 80 80 After 5 years through 10 years 41 41 53 54 After 10 years 291 283 349 333 Total asset-backed securities 372 363 482 467 Corporate debt: 1 year or less 1 1 — — After 1 year through 5 years 74 74 73 74 After 5 years through 10 years 11 12 20 21 After 10 years — — 13 14 Total corporate debt 86 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 $ 14,279 $ 13,727 $ 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 September 30, 2018 and December 31, 2017 : Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value September 30, 2018 U.S. Treasury $ 5 $ — $ — $ 5 Federal agencies: Residential CMO 7,307 — (367 ) 6,940 Residential MBS 646 — (26 ) 620 Commercial MBS 1,783 — (80 ) 1,703 Other agencies 162 — (5 ) 157 Total U.S. Treasury, Federal agency and other agency securities 9,903 — (478 ) 9,425 Municipal securities 3,914 11 (77 ) 3,848 Asset-backed securities 372 — (9 ) 363 Corporate debt 86 1 — 87 Other securities/Sovereign debt 4 — — 4 Total available-for-sale securities $ 14,279 $ 12 $ (564 ) $ 13,727 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 September 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 September 30, 2018 Federal agencies: Residential CMO $ 2,286 $ (77 ) $ 4,632 $ (290 ) $ 6,918 $ (367 ) Residential MBS 542 (23 ) 70 (3 ) 612 (26 ) Commercial MBS 109 (4 ) 1,594 (76 ) 1,703 (80 ) Other agencies 80 (2 ) 72 (3 ) 152 (5 ) Total Federal Agency and other agency securities 3,017 (106 ) 6,368 (372 ) 9,385 (478 ) Municipal securities 1,846 (39 ) 1,278 (38 ) 3,124 (77 ) Asset-backed securities 157 (3 ) 146 (6 ) 303 (9 ) Corporate debt 65 — — — 65 — Other securities/Sovereign debt — — — — — — Total temporarily impaired securities $ 5,085 $ (148 ) $ 7,792 $ (416 ) $ 12,877 $ (564 ) 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 nine-month periods ended September 30, 2018 and 2017 , respectively. Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Gross gains on sales of securities $ — $ 4 $ 6 $ 8 Gross losses on sales of securities (2 ) (4 ) (8 ) (4 ) Net (loss) gain on sales of securities $ (2 ) $ — $ (2 ) $ 4 OTTI recognized in earnings — — — (4 ) Net securities losses $ (2 ) $ — $ (2 ) $ —

HELD-TO-MATURITY SECURITIES (Ta

HELD-TO-MATURITY SECURITIES (Tables)	9 Months Ended
HELD-TO-MATURITY SECURITIES (Tables)	Sep. 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 September 30, 2018 and December 31, 2017 . September 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 36 35 — — After 10 years 2,167 2,073 3,714 3,657 Total Residential CMO 2,203 2,108 3,714 3,657 Residential MBS: After 5 years through 10 years — — 28 28 After 10 years 1,624 1,555 1,021 1,016 Total Residential MBS 1,624 1,555 1,049 1,044 Commercial MBS: After 1 year through 5 years — — 38 37 After 5 years through 10 years 130 126 1 1 After 10 years 4,141 3,968 3,752 3,698 Total Commercial MBS 4,271 4,094 3,791 3,736 Other agencies: After 1 year through 5 years 12 12 7 8 After 5 years through 10 years 204 197 362 360 After 10 years 146 141 163 161 Total other agencies 362 350 532 529 Total Federal agencies and other agencies 8,460 8,107 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 $ 8,465 $ 8,112 $ 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 September 30, 2018 and December 31, 2017 . Unrealized (dollar amounts in millions) Amortized Cost Gross Gains Gross Losses Fair Value September 30, 2018 Federal agencies: Residential CMO $ 2,203 $ — $ (95 ) $ 2,108 Residential MBS 1,624 — (69 ) 1,555 Commercial MBS 4,271 — (177 ) 4,094 Other agencies 362 — (12 ) 350 Total Federal agencies and other agencies 8,460 — (353 ) 8,107 Municipal securities 5 — — 5 Total held-to-maturity securities $ 8,465 $ — $ (353 ) $ 8,112 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 September 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 September 30, 2018 Federal agencies: Residential CMO $ 557 $ (21 ) $ 1,551 $ (74 ) $ 2,108 $ (95 ) Residential MBS 807 (33 ) 748 (36 ) 1,555 (69 ) Commercial MBS 410 (15 ) 3,683 (162 ) 4,093 (177 ) Other agencies 192 (6 ) 138 (6 ) 330 (12 ) Total Federal agencies and other agencies 1,966 (75 ) 6,120 (278 ) 8,086 (353 ) Municipal securities — — 4 — 4 — Total temporarily impaired securities $ 1,966 $ (75 ) $ 6,124 $ (278 ) $ 8,090 $ (353 ) 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)	9 Months Ended
OTHER SECURITIES (Tables)	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Other Securities	September 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 248 248 287 287 Federal Reserve Bank stock 295 295 294 294 Other securities, at fair value Mutual funds 20 20 18 18 Marketable equity securities 1 2 1 1 Total other securities $ 564 $ 565 $ 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)	9 Months Ended
LOAN SALES AND SECURITIZATIONS (Tables)	Sep. 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 nine-month periods ended September 30, 2018 and 2017 : Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Residential mortgage loans sold with servicing retained $ 1,047 $ 1,179 $ 2,787 $ 2,824 Pretax gains resulting from above loan sales (1) 24 27 64 66 (1) Recorded in mortgage banking income.
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 nine-month periods ended September 30, 2018 and 2017 : Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Carrying value, beginning of period $ 204 $ 176 $ 191 $ 172 New servicing assets created 12 13 32 31 Impairment recovery (charge) — 1 7 — Amortization (8 ) (7 ) (22 ) (20 ) Carrying value, end of period $ 208 $ 183 $ 208 $ 183 Fair value, end of period $ 222 $ 184 $ 222 $ 184 Weighted-average life (years) 7.1 7.0 7.1 7.0
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 September 30, 2018 , and December 31, 2017 follows: September 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) 8.10 % $ (5 ) $ (10 ) 8.30 % $ (5 ) $ (10 ) Spread over forward interest rate swap rates 941 bps (7 ) (14 ) 1,049 bps (7 ) (13 )

OTHER COMPREHENSIVE INCOME (Tab

OTHER COMPREHENSIVE INCOME (Tables)	9 Months Ended
OTHER COMPREHENSIVE INCOME (Tables)	Sep. 30, 2018
Equity [Abstract]
Components of other comprehensive income	The components of Huntington's OCI for the three-month and nine-month periods ended September 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 (82 ) 18 (64 ) Less: Reclassification adjustment for net losses (gains) included in net income 3 (1 ) 2 Net change in unrealized holding gains (losses) on available-for-sale debt securities (79 ) 17 (62 ) Net change in pension and other post-retirement obligations 2 (1 ) 1 Total other comprehensive income (loss) $ (77 ) $ 16 $ (61 ) 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 (42 ) 15 (27 ) Less: Reclassification adjustment for net losses (gains) included in net income 9 (4 ) 5 Net change in unrealized holding gains (losses) on available-for-sale debt securities (33 ) 11 (22 ) Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period 2 — 2 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 — 2 Net change in pension and other post-retirement obligations 2 (1 ) 1 Total other comprehensive income (loss) $ (29 ) $ 10 $ (19 ) Nine 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 (359 ) 78 (281 ) Less: Reclassification adjustment for net losses (gains) included in net income 21 (4 ) 17 Net change in unrealized holding gains (losses) on available-for-sale debt securities (338 ) 74 (264 ) Net change in pension and other post-retirement obligations 4 (1 ) 3 Total other comprehensive income (loss) $ (334 ) $ 73 $ (261 ) Nine 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 20 (7 ) 13 Less: Reclassification adjustment for net losses (gains) included in net income 19 (7 ) 12 Net change in unrealized holding gains (losses) on available-for-sale debt securities 42 (15 ) 27 Unrealized gains (losses) on derivatives used in cash flow hedging relationships arising during the period 2 — 2 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 3 (1 ) 2 Net change in pension and other post-retirement obligations 3 (1 ) 2 Total other comprehensive income (loss) $ 48 $ (17 ) $ 31
Activity in accumulated other comprehensive income, net of tax	ctivity in accumulated OCI for the nine -month periods ended September 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, 2017 $ (278 ) $ — $ (250 ) $ (528 ) Cumulative-effect adjustments (ASU 2016-01) (1 ) — — (1 ) Other comprehensive income before reclassifications (281 ) — — (281 ) Amounts reclassified from accumulated OCI to earnings 17 — 3 20 Period change (264 ) — 3 (261 ) September 30, 2018 $ (543 ) $ — $ (247 ) $ (790 ) December 31, 2016 $ (193 ) $ (3 ) $ (205 ) $ (401 ) Other comprehensive income before reclassifications 15 2 — 17 Amounts reclassified from accumulated OCI to earnings 12 — 2 14 Period change 27 2 2 31 September 30, 2017 $ (166 ) $ (1 ) $ (203 ) $ (370 )
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 nine-month periods ended September 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) September 30, 2018 September 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (3 ) $ (1 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities — (8 ) Noninterest income - net gains (losses) on sale of securities OTTI recorded — — Noninterest income - net gains (losses) on sale of securities Total before tax (3 ) (9 ) Tax (expense) benefit 1 4 Net of tax $ (2 ) $ (5 ) Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (2 ) $ (1 ) Noninterest income / expense (1) Net periodic benefit costs — (1 ) Noninterest income / expense (1) Total before tax (2 ) (2 ) Tax (expense) benefit 1 1 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 Nine Months Ended (dollar amounts in millions) September 30, 2018 September 30, 2017 Gains (losses) on debt securities: Amortization of unrealized gains (losses) $ (9 ) $ (7 ) Interest income - held-to-maturity securities - taxable Realized gain (loss) on sale of securities (12 ) (8 ) Noninterest income - net gains (losses) on sale of securities OTTI recorded — (4 ) Noninterest income - net gains (losses) on sale of securities Total before tax (21 ) (19 ) Tax (expense) benefit 4 7 Net of tax $ (17 ) $ (12 ) Gains (losses) on cash flow hedging relationships: Interest rate contracts $ — $ (1 ) Interest income - loans and leases Interest rate contracts — — Noninterest income - other income Total before tax — (1 ) Tax (expense) benefit — 1 Net of tax $ — $ — Amortization of defined benefit pension and post-retirement items: Actuarial gains (losses) $ (6 ) $ (4 ) Noninterest income / expense (1) Net periodic benefit costs 2 1 Noninterest income / expense (1) Total before tax (4 ) (3 ) Tax (expense) benefit 1 1 Net of tax $ (3 ) $ (2 ) (1) The activity for 2018 and 2017 is recorded in Noninterest Income - other noninterest income and Noninterest Expense - personnel costs, respectively, on the Condensed Consolidated Statements of Income.

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	9 Months Ended
SHAREHOLDERS' EQUITY (Tables)	Sep. 30, 2018
Equity [Abstract]
Schedule of Preferred Stock	The following is a summary of Huntington's non-cumulative perpetual preferred stock outstanding as of September 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)	9 Months Ended
EARNINGS PER SHARE (Tables)	Sep. 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 nine -month periods ended September 30, 2018 and 2017 was as follows: Three Months Ended Nine Months Ended (dollar amounts in millions, share amounts in thousands) 2018 2017 2018 2017 Basic earnings per common share: Net income $ 378 $ 275 $ 1,059 $ 754 Preferred stock dividends (18 ) (19 ) (51 ) (57 ) Net income available to common shareholders $ 360 $ 256 $ 1,008 $ 697 Average common shares issued and outstanding 1,084,536 1,086,038 1,090,570 1,087,115 Basic earnings per common share $ 0.33 $ 0.24 $ 0.92 $ 0.64 Diluted earnings per common share: Net income available to common shareholders $ 360 $ 256 $ 1,008 $ 697 Effect of assumed preferred stock conversion — — — — Net income applicable to diluted earnings per share $ 360 $ 256 $ 1,008 $ 697 Average common shares issued and outstanding 1,084,536 1,086,038 1,090,570 1,087,115 Dilutive potential common shares: Stock options and restricted stock units and awards 15,655 17,079 17,105 17,515 Shares held in deferred compensation plans 3,549 3,228 3,416 3,096 Dilutive impact of Preferred Stock — — 5,887 — Other — 146 — 152 Dilutive potential common shares 19,204 20,453 26,408 20,763 Total diluted average common shares issued and outstanding 1,103,740 1,106,491 1,116,978 1,107,878 Diluted earnings per common share $ 0.33 $ 0.23 $ 0.90 $ 0.63

NON-INTEREST INCOME (Tables)

NON-INTEREST INCOME (Tables)	9 Months Ended
NON-INTEREST INCOME (Tables)	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Schedule of Non-interest Income	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 September 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 $ 75 $ 16 $ 1 $ 1 $ — $ 93 Cards and payment processing income 50 3 — — — 53 Trust and investment management services 7 1 — 34 — 42 Insurance income 8 1 — 10 — 19 Other income 10 2 1 2 1 16 Net revenue from contracts with customers $ 150 $ 23 $ 2 $ 47 $ 1 $ 223 Noninterest income within the scope of other GAAP topics 42 56 — — 21 119 Total noninterest income $ 192 $ 79 $ 2 $ 47 $ 22 $ 342 Nine Months Ended September 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 $ 215 $ 48 $ 4 $ 3 $ — $ 270 Cards and payment processing income 146 8 — — — 154 Trust and investment management services 19 3 — 106 — 128 Insurance income 26 3 — 31 1 61 Other Income 30 3 2 4 2 41 Net revenue from contracts with customers $ 436 $ 65 $ 6 $ 144 $ 3 $ 654 Noninterest income within the scope of other GAAP topics 117 163 2 1 55 338 Total noninterest income $ 553 $ 228 $ 8 $ 145 $ 58 $ 992 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 September 30, 2018 Nine Months Ended September 30, 2018 Noninterest income Noninterest income from contracts with customers $ 223 $ 654 Noninterest income within the scope of other GAAP topics 119 338 Total noninterest income $ 342 $ 992

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	9 Months Ended
BENEFIT PLANS (Tables)	Sep. 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 September 30, Three Months Ended September 30, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ — $ — $ — $ — Interest cost 9 8 — — Expected return on plan assets (12 ) (13 ) — — Amortization of prior service cost — — (1 ) — Amortization of loss 2 1 — — Settlements 1 4 — — Net periodic (benefit) cost $ — $ — $ (1 ) $ — Pension Benefits (1) Post-Retirement Benefits (1) Nine Months Ended September 30, Nine Months Ended September 30, (dollar amounts in millions) 2018 2017 2018 2017 Service cost $ 2 $ 2 $ — $ — Interest cost 23 22 — — Expected return on plan assets (36 ) (41 ) — — Amortization of prior service cost — — (2 ) (1 ) Amortization of loss 6 5 — — Settlements 6 10 — — Net periodic (benefit) cost $ 1 $ (2 ) $ (2 ) $ (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, in the Condensed Consolidated Statements of Income.
Schedule of Costs of Retirement Plans	Huntington's expense related to the defined contribution plans during the third quarter 2018 and 2017 was $7 million and $5 million , respectively. For the nine-month period ended September 30, 2018 and 2017 , expense related to the defined contribution plans was $35 million and $26 million , respectively.

FAIR VALUES OF ASSETS AND LIA_2

FAIR VALUES OF ASSETS AND LIABILITIES (Tables)	9 Months Ended
FAIR VALUES OF ASSETS AND LIABILITIES (Tables)	Sep. 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 September 30, 2018 and December 31, 2017 are summarized below: Fair Value Measurements at Reporting Date Using Netting Adjustments (1) September 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Assets Trading account securities: Municipal securities $ — $ 5 $ — $ — $ 5 Other securities 77 1 — — 78 77 6 — — 83 Available-for-sale securities: U.S. Treasury securities 5 — — — 5 Residential CMOs — 6,940 — — 6,940 Residential MBS — 620 — — 620 Commercial MBS — 1,703 — — 1,703 Other agencies — 157 — — 157 Municipal securities — 571 3,277 — 3,848 Asset-backed securities — 363 — — 363 Corporate debt — 87 — — 87 Other securities/sovereign debt — 4 — — 4 5 10,445 3,277 — 13,727 Other securities 22 — — — 22 Loans held for sale — 727 — — 727 Loans held for investment — 49 32 — 81 MSRs — — 11 — 11 Derivative assets — 493 5 (318 ) 180 Liabilities Derivative liabilities — 437 4 (221 ) 220 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 $ 11 $ 1 $ 3,178 $ 34 Transfers out of Level 3 (1) — (12 ) — — Total gains/losses for the period: Included in earnings — 9 (1 ) — Included in OCI — — — — Purchases/originations — — 260 — Sales — — — — Repayments — — — (2 ) Settlements — 3 (160 ) — Closing balance $ 11 $ 1 $ 3,277 $ 32 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ (3 ) $ — $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Opening balance $ 13 $ 3 $ 2,872 $ 43 $ 44 Transfers out of Level 3 (1) — (1 ) — — — Total gains/losses for the period: Included in earnings (1 ) 1 (1 ) (2 ) — Included in OCI — — (34 ) 5 — Purchases/originations — — 167 — — Sales — — — (22 ) — Repayments — — — — (4 ) Settlements — — (46 ) — — Closing balance $ 12 $ 3 $ 2,958 $ 24 $ 40 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (1 ) $ 1 $ — $ — $ — (1) Transfers out of Level 3 represent the settlement value of the derivative instruments (i.e. interest rate lock agreements) that is transferred to loans held for sale, which is classified as Level 2. 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 out of Level 3 (1) — (26 ) — — — Total gains/losses for the period: Included in earnings — 25 (3 ) (2 ) — Included in OCI — — (37 ) 11 — Purchases/originations — — 539 — — Sales — — — (33 ) — Repayments — — — — (6 ) Settlements — 3 (389 ) — — Closing balance $ 11 $ 1 $ 3,277 $ — $ 32 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ — $ (1 ) $ — $ — $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset- backed securities Loans held for investment Opening balance $ 14 $ (2 ) $ 2,798 $ 76 $ 48 Transfers out of Level 3 (1) — (4 ) — — — Total gains/losses for the period: Included in earnings (2 ) 9 (4 ) (5 ) 1 Included in OCI — — (1 ) 13 — Purchases/originations — — 414 — — Sales — — — (59 ) — Repayments — — — — (9 ) Settlements — — (249 ) (1 ) — Closing balance $ 12 $ 3 $ 2,958 $ 24 $ 40 Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date $ (2 ) $ 9 $ — $ (4 ) $ —
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 nine-month periods ended September 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 $ — $ 9 $ — $ — Other expense — — (1 ) — Total $ — $ 9 $ (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 $ (1 ) $ 1 $ — $ — $ — Securities gains (losses) — — — (2 ) — Interest and fee income — — (1 ) — — Total $ (1 ) $ 1 $ (1 ) $ (2 ) $ — Level 3 Fair Value Measurements Available-for-sale securities (dollar amounts in millions) MSRs Derivative instruments Municipal securities Asset-backed securities Loans held for investment Classification of gains and losses in earnings: Mortgage banking income $ — $ 25 $ — $ — $ — Securities gains (losses) — — — (2 ) — Other expense — — (3 ) — — Total $ — $ 25 $ (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 $ (2 ) $ 9 $ — $ — $ — Securities gains (losses) — — — (5 ) — Interest and fee income — — (4 ) — — Noninterest income — — — — 1 Total $ (2 ) $ 9 $ (4 ) $ (5 ) $ 1
Assets and liabilities under the fair value option	The following tables present the fair value and aggregate principal balance of certain assets and liabilities under the fair value option: September 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 $ 727 $ 713 $ 14 $ — $ — $ — Loans held for investment 81 88 (7 ) 6 7 (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 nine-month periods ended September 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 September 30, Nine Months Ended September 30, Assets 2018 2017 2018 2017 Loans held for sale $ (4 ) $ (2 ) $ (1 ) $ 12 Loans held for investment — — — 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 53 — — 53 1 Other real estate owned 27 — — 27 (1 )
Quantitative information about significant unobservable level 3 fair value measurement inputs	Quantitative Information about Level 3 Fair Value Measurements at September 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% - 54% (8%) Spread over forward interest rate 5% - 11% (8%) Derivative assets 5 Consensus Pricing Net market price -4%-8%(1%) Estimated Pull through % 3% - 100% (91%) Derivative liabilities 4 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 6/30/2020 Municipal securities 3,277 Discounted cash flow Discount rate 3% - 4% (3%) Cumulative default 0% - 64% (4%) Loss given default 5% - 90% (25%) Loans held for investment 32 Discounted cash flow Discount rate 7% (7%) Constant prepayment rate 9% (9%) Measured at fair value on a nonrecurring basis: Impaired loans 53 Appraisal value NA NA Other real estate owned 27 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 September 30, 2018 and December 31, 2017 : September 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 1,342 — — 1,342 1,342 Trading account securities — — 83 83 83 Available-for-sale securities — — 13,727 13,727 13,727 Held-to-maturity securities 8,465 — — 8,465 8,112 Other securities 543 — 22 565 565 Loans held for sale — 65 727 792 795 Net loans and direct financing leases (1) 72,528 — 81 72,609 71,918 Derivatives — — 180 180 180 Financial Liabilities Deposits 81,689 — — 81,689 81,631 Short-term borrowings 1,348 — — 1,348 1,348 Long-term debt 9,385 — — 9,385 9,523 Derivatives — — 220 220 220 (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 September 30, 2018 and December 31, 2017 : Estimated Fair Value Measurements at Reporting Date Using September 30, 2018 (dollar amounts in millions) Level 1 Level 2 Level 3 Financial Assets Trading account securities $ 77 $ 6 $ — $ 83 Available-for-sale securities 5 10,445 3,277 13,727 Held-to-maturity securities — 8,112 — 8,112 Other securities 22 — — 22 Loans held for sale — 727 68 795 Net loans and direct financing leases — 49 71,869 71,918 Financial Liabilities Deposits — 74,423 7,208 81,631 Short-term borrowings 2 — 1,346 1,348 Long-term debt — 8,986 537 9,523 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 INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	9 Months Ended
DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset and liability derivatives included in accrued income and other assets	September 30, 2018 December 31, 2017 (dollar amounts in millions) Asset Liability Asset Liability Derivatives designated as Hedging Instruments Interest rate contracts $ 15 $ 65 $ 22 $ 121 Derivatives not designated as Hedging Instruments Interest rate contracts 294 198 187 100 Foreign exchange contracts 28 22 18 18 Commodities contracts 157 152 92 87 Equity contracts 4 4 3 5 Total Contracts $ 498 $ 441 $ 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 nine-month periods ended September 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 September 30, 2018 Nine Months Ended September 30, 2018 Interest rate contracts: Customer Capital markets fees $ 11 $ 30 Mortgage Banking Mortgage banking income 5 (3 ) Foreign exchange contracts Capital markets fees 6 18 Commodities contracts Capital markets fees 1 3 Equity contracts Other noninterest expense — 3 Total $ 23 $ 51
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 September 30, 2018 and December 31, 2017 , identified by the underlying interest rate-sensitive instruments. September 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 5,340 — 5,340 Total notional value at September 30, 2018 $ 5,715 $ 12 $ 5,727 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 September 30, 2018 and December 31, 2017 . September 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 1.5 $ — 2.20 % 2.16 % Liability conversion swaps Receive fixed—generic 5,715 2.5 (50 ) 2.08 2.26 Total swap portfolio at September 30, 2018 $ 5,727 2.5 $ (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 nine-month periods ended September 30, 2018 and 2017 . Three Months Ended Nine 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) $ (2 ) $ (2 ) $ 22 $ (5 ) Change in fair value of hedged subordinated notes (1) 2 4 (22 ) 7 Change in fair value of interest rate swaps hedging other long-term debt (1) (9 ) (6 ) 33 (1 ) Change in fair value of hedged other long-term debt (1) 10 7 (27 ) (1 ) (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 September 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) September 30, 2018 September 30, 2018 Long-term debt $ 5,637 $ (67 ) The cumulative amount of fair value hedging adjustments remaining for any hedged assets and liabilities for which hedge accounting has been discontinued is $(135) million at September 30, 2018 .
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 September 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 September 30, 2018 Derivatives $ 498 $ (318 ) $ 180 $ (2 ) $ (59 ) $ 119 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 September 30, 2018 Derivatives $ 441 $ (221 ) $ 220 $ — $ (15 ) $ 205 December 31, 2017 Derivatives 331 (245 ) 86 — (21 ) 65

VIEs (Tables)

VIEs (Tables)	9 Months Ended
VIEs (Tables)	Sep. 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 September 30, 2018 , and December 31, 2017 : September 30, 2018 (dollar amounts in millions) Total Assets Total Liabilities Maximum Exposure to Loss 2016-1 Automobile Trust $ 3 $ 1 $ 3 2015-1 Automobile Trust — — — Trust Preferred Securities 14 252 — Affordable Housing Tax Credit Partnerships 683 345 683 Other Investments 125 54 125 Total $ 825 $ 652 $ 811 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 September 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 3.10 % (2) $ 70 $ 6 Huntington Capital II 3.02 (3) 32 3 Sky Financial Capital Trust III 3.80 (4) 72 2 Sky Financial Capital Trust IV 3.80 (4) 74 2 Camco Financial Trust 3.73 (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 September 30, 2018 , based on three-month LIBOR + 0.70% . (3) Variable effective rate at September 30, 2018 , based on three-month LIBOR + 0.625% . (4) Variable effective rate at September 30, 2018 , based on three-month LIBOR + 1.40% . (5) Variable effective rate at September 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 September 30, 2018 and December 31, 2017 . (dollar amounts in millions) September 30, December 31, Affordable housing tax credit investments $ 1,102 $ 996 Less: amortization (419 ) (360 ) Net affordable housing tax credit investments $ 683 $ 636 Unfunded commitments $ 345 $ 335 The following table presents other information relating to Huntington’s affordable housing tax credit investments for the three-month and nine-month periods ended September 30, 2018 and 2017 . Three Months Ended Nine Months Ended (dollar amounts in millions) 2018 2017 2018 2017 Tax credits and other tax benefits recognized $ 24 $ 22 $ 70 $ 68 Proportional amortization method Tax credit amortization expense included in provision for income taxes 19 17 59 51

COMMITMENTS AND CONTINGENT LI_2

COMMITMENTS AND CONTINGENT LIABILITIES (Tables)	9 Months Ended
COMMITMENTS AND CONTINGENT LIABILITIES (Tables)	Sep. 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 September 30, 2018 and December 31, 2017 , were as follows: (dollar amounts in millions) September 30, December 31, Contract amount representing credit risk Commitments to extend credit: Commercial $ 16,594 $ 16,219 Consumer 14,798 13,384 Commercial real estate 1,182 1,366 Standby letters of credit 623 510 Commercial letters-of-credit 33 21

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	9 Months Ended
SEGMENT REPORTING (Tables)	Sep. 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 September 30, 2018 , December 31, 2017 , and September 30, 2017 , reported results by business segment. Three Months Ended September 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 431 $ 239 $ 101 $ 48 $ (17 ) $ 802 Provision (benefit) for credit losses 42 (1 ) 12 — — 53 Noninterest income 192 79 2 47 22 342 Noninterest expense 425 124 37 61 4 651 Provision (benefit) for income taxes 33 41 11 7 (30 ) 62 Net income (loss) $ 123 $ 154 $ 43 $ 27 $ 31 $ 378 2017 Net interest income $ 391 $ 224 $ 108 $ 43 $ (8 ) $ 758 Provision (benefit) for credit losses 24 — 20 — (1 ) 43 Noninterest income 189 67 3 46 25 330 Noninterest expense 416 117 39 58 50 680 Provision (benefit) for income taxes 49 61 18 11 (49 ) 90 Net income (loss) $ 91 $ 113 $ 34 $ 20 $ 17 $ 275 Nine Months Ended September 30, Income Statements Consumer & Business Banking Commercial Banking Vehicle Finance RBHPCG Treasury / Other Huntington Consolidated (dollar amounts in millions) 2018 Net interest income $ 1,239 $ 688 $ 300 $ 139 $ (10 ) $ 2,356 Provision (benefit) for credit losses 101 38 36 — — 175 Noninterest income 553 228 8 145 58 992 Noninterest expense 1,266 373 110 184 3 1,936 Provision (benefit) for income taxes 89 106 34 21 (72 ) 178 Net income (loss) $ 336 $ 399 $ 128 $ 79 $ 117 $ 1,059 2017 Net interest income $ 1,151 $ 675 $ 318 $ 126 $ (37 ) $ 2,233 Provision (benefit) for credit losses 75 15 45 1 — 136 Noninterest income 544 201 11 141 70 967 Noninterest expense 1,242 353 113 182 192 2,082 Provision (benefit) for income taxes 132 178 60 29 (171 ) 228 Net income (loss) $ 246 $ 330 $ 111 $ 55 $ 12 $ 754 Assets at Deposits at (dollar amounts in millions) September 30, December 31, September 30, December 31, Consumer & Business Banking $ 27,362 $ 26,220 $ 49,434 $ 45,643 Commercial Banking 33,759 32,118 22,288 21,235 Vehicle Finance 18,895 17,865 348 358 RBHPCG 6,374 5,821 5,783 6,057 Treasury / Other 19,262 22,161 3,836 3,748 Total $ 105,652 $ 104,185 $ 81,689 $ 77,041
Segment Disclosure of Assets and Deposits	Assets at Deposits at (dollar amounts in millions) September 30, December 31, September 30, December 31, Consumer & Business Banking $ 27,362 $ 26,220 $ 49,434 $ 45,643 Commercial Banking 33,759 32,118 22,288 21,235 Vehicle Finance 18,895 17,865 348 358 RBHPCG 6,374 5,821 5,783 6,057 Treasury / Other 19,262 22,161 3,836 3,748 Total $ 105,652 $ 104,185 $ 81,689 $ 77,041

LOANS _ LEASES AND ALLOWANCE _3

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details)	3 Months Ended
	Sep. 30, 2018USD ($)reserve	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ALLL balance	$ 761,000,000	$ 741,000,000	$ 691,000,000	$ 675,000,000	$ 668,000,000	$ 638,000,000
Loans and leases receivable net premium	$ 408,000,000		334,000,000
Number of days past due	30 days
Allowance number of reserves \| reserve	2
Collateral for secured borrowings	$ 44,100,000,000		31,700,000,000
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ALLL balance	$ 543,000,000	531,000,000	482,000,000	474,000,000	475,000,000	451,000,000
Threshold period past due for nonperforming status	90 days
Threshold period past due for write-off	90 days
Threshold outstanding balance for quarterly impairment evaluation	$ 1,000,000
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total ALLL balance	$ 218,000,000	$ 210,000,000	$ 209,000,000	$ 201,000,000	$ 193,000,000	$ 187,000,000
Threshold period past due for write-off	120 days

LOANS _ LEASES AND ALLOWANCE _4

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Loan and Lease Portfolio Composition (Details) - USD ($) $ in Millions		Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial		$ 29,196		$ 28,107
Commercial real estate		7,073		7,225
Automobile		12,375		12,100
Home equity		9,850		10,099
Residential mortgage		10,459		9,026
Recreation Finance		3,152		2,438
Other consumer		1,265		1,122
Loans and leases	[1]	73,370		70,117
Allowance for loan and lease losses		(761)	$ (741)	(691)	$ (675)	$ (668)	$ (638)
Net loans and leases		72,609		69,426
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile		12,375		12,099
Home equity		9,848		10,097
Residential mortgage		10,380		8,937
Other consumer		1,265		1,122
Allowance for loan and lease losses		(218)	(210)	(209)	(201)	(193)	(187)
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		12,375		12,100
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		9,850		10,099
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		10,459		9,026
Consumer \| RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		3,152		2,438
Consumer \| Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		1,265		1,122
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial		29,196		28,107
Commercial real estate		7,073		7,225
Allowance for loan and lease losses		(543)	$ (531)	(482)	$ (474)	$ (475)	$ (451)
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		29,196		28,107
Commercial \| Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases		$ 7,073		$ 7,225

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

LOANS _ LEASES AND ALLOWANCE _5

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Nonaccrual Loans by Loan Class (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 370	$ 349
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	211	161
Commercial \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	19	29
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	5	6
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	67	68
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	67	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 _6

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - NALs Past Due (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		$ 707	$ 714
Current		72,582	69,269
Purchased Credit Impaired			41
Consumer loans		81	93
Loans and leases	[1]	73,370	70,117
90 or more days past due and accruing		154	115
30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		315	335
60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		101	108
90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		291	271
Commercial \| Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		123	114
Current		29,073	27,954
Purchased Credit Impaired			39
Consumer loans		0	0
Loans and leases		29,196	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)		48	35
Commercial \| Commercial and Industrial \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		17	14
Commercial \| Commercial and Industrial \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		58	65
Commercial \| Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		14	22
Current		7,059	7,201
Purchased Credit Impaired			2
Consumer loans		0	0
Loans and leases		7,073	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)		6	10
Commercial \| Real Estate \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		1	1
Commercial \| Real Estate \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		7	11
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		101	117
Current		12,274	11,982
Purchased Credit Impaired			0
Consumer loans		0	1
Loans and leases		12,375	12,100
90 or more days past due and accruing		7	7
Consumer \| Automobile \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		77	89
Consumer \| Automobile \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		16	18
Consumer \| Automobile \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		8	10
Consumer \| Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		123	128
Current		9,725	9,969
Purchased Credit Impaired			0
Consumer loans		2	2
Loans and leases		9,850	10,099
90 or more days past due and accruing		15	18
Consumer \| Home Equity \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		46	49
Consumer \| Home Equity \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		17	19
Consumer \| Home Equity \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		60	60
Consumer \| Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		309	295
Current		10,071	8,642
Purchased Credit Impaired			0
Consumer loans		79	89
Loans and leases		10,459	9,026
90 or more days past due and accruing		117	72
Consumer \| Residential Mortgage \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		116	129
Consumer \| Residential Mortgage \| 60-89 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		42	48
Consumer \| Residential Mortgage \| 90 or more days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		151	118
Consumer \| RV and Marine FInance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		13	16
Current		3,139	2,421
Purchased Credit Impaired			0
Consumer loans		0	1
Loans and leases		3,152	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)		9	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)		2	2
Consumer \| Other Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		24	22
Current		1,241	1,100
Purchased Credit Impaired			0
Consumer loans		0	0
Loans and leases		1,265	1,122
90 or more days past due and accruing		5	5
Consumer \| Other Consumer \| 30-59 Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past Due (1)		13	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)		$ 5	$ 5

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

LOANS _ LEASES AND ALLOWANCE _7

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Portion of ALLL balance:
ALLL balance, beginning of period	$ 741	$ 668	$ 691	$ 638
Loan charge-offs	(58)	(65)	(184)	(192)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	29	22	89	74
Provision for Loan and Lease Losses	53	43	175	136
Provision For (Reduction In Allowance) Loan and Lease Losses.	49	50	165	155
ALLL balance, end of period	761	675	761	675
AULC Balance, beginning of period	93	85	87	98
Provision (reduction in allowance) for unfunded loan commitments and letters of credit	4	(6)	10	(19)
AULC Balance, end of period	97	79	97	79
ACL balance, end of period	858	754	858	754
Commercial
Portion of ALLL balance:
ALLL balance, beginning of period	531	475	482	451
Loan charge-offs	(11)	(19)	(46)	(58)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	15	10	45	34
Provision for Loan and Lease Losses		8
Provision For (Reduction In Allowance) Loan and Lease Losses.	8		62	47
ALLL balance, end of period	543	474	543	474
AULC Balance, beginning of period	90	82	84	87
Provision (reduction in allowance) for unfunded loan commitments and letters of credit	5	(6)	11	(11)
AULC Balance, end of period	95	76	95	76
ACL balance, end of period	638	550	638	550
Consumer
Portion of ALLL balance:
ALLL balance, beginning of period	210	193	209	187
Loan charge-offs	(47)	(46)	(138)	(134)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	14	12	44	40
Provision for Loan and Lease Losses		42
Provision For (Reduction In Allowance) Loan and Lease Losses.	41		103	108
ALLL balance, end of period	218	201	218	201
AULC Balance, beginning of period	3	3	3	11
Provision (reduction in allowance) for unfunded loan commitments and letters of credit	(1)	0	(1)	(8)
AULC Balance, end of period	2	3	2	3
ACL balance, end of period	$ 220	$ 204	$ 220	$ 204

LOANS _ LEASES AND ALLOWANCE _8

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Credit Quality Indicators (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	$ 29,196	$ 28,107
Commercial real estate	7,073	7,225
Automobile	12,375	12,100
Home equity	9,850	10,099
Residential mortgage	10,459	9,026
Other consumer	1,265	1,122
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	29,196	28,107
Commercial real estate	7,073	7,225
Commercial \| Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	27,407	26,268
Commercial real estate	6,766	6,909
Commercial \| Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	1,104	1,116
Commercial real estate	117	115
Commercial \| OLEM
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	678	694
Commercial real estate	189	200
Commercial \| Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial and industrial	7	29
Commercial real estate	1	1
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	12,375	12,099
Home equity	9,848	10,097
Residential mortgage	10,380	8,937
RV and marine finance	3,152	2,437
Other consumer	1,265	1,122
Consumer \| Greater than 750
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	6,233	6,102
Home equity	6,173	6,352
Residential mortgage	6,841	5,697
RV and marine finance	2,007	1,433
Other consumer	471	428
Consumer \| 650-749
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	4,503	4,312
Home equity	2,963	3,024
Residential mortgage	2,783	2,581
RV and marine finance	966	863
Other consumer	612	540
Consumer \| Less Than 650
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	1,350	1,390
Home equity	650	617
Residential mortgage	622	605
RV and marine finance	101	96
Other consumer	124	143
Consumer \| Other FICO score
Accounts, Notes, Loans and Financing Receivable [Line Items]
Automobile	289	295
Home equity	62	104
Residential mortgage	134	54
RV and marine finance	78	45
Other consumer	$ 58	$ 11

LOANS _ LEASES AND ALLOWANCE _9

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - ALLL Attributable to Loans by Portfolio Segment (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Portion of ALLL balance:
Attributable to loans individually evaluated for impairment	$ 56		$ 41
Attributable to loans collectively evaluated for impairment	705		650
Total ALLL balance	761	$ 741	691	$ 675	$ 668	$ 638
Portion of loan and lease ending balance:
Collectively evaluated for impairment	72,068		68,760
Individually evaluated for impairment	1,221		1,223
Financing Receivable Evaluated For Impairment	73,289		70,024
Commercial
Portion of ALLL balance:
Attributable to loans individually evaluated for impairment	46		32
Attributable to loans collectively evaluated for impairment	497		450
Total ALLL balance	543	531	482	474	475	451
Portion of loan and lease ending balance:
Collectively evaluated for impairment	35,646		34,684
Individually evaluated for impairment	623		607
Financing Receivable Evaluated For Impairment	36,269		35,332
Consumer
Portion of ALLL balance:
Attributable to loans individually evaluated for impairment	10		9
Attributable to loans collectively evaluated for impairment	208		200
Total ALLL balance	218	$ 210	209	$ 201	$ 193	$ 187
Portion of loan and lease ending balance:
Collectively evaluated for impairment	36,422		34,076
Individually evaluated for impairment	598		616
Financing Receivable Evaluated For Impairment	$ 37,020		34,692
Purchased credit-impaired
Portion of loan and lease ending balance:
Collectively evaluated for impairment			41
Purchased credit-impaired \| Commercial
Portion of loan and lease ending balance:
Collectively evaluated for impairment			41
Purchased credit-impaired \| Consumer
Portion of loan and lease ending balance:
Collectively evaluated for impairment			$ 0

LOANS _ LEASES AND ALLOWANCE_10

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - Impaired Loans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	252		252		284
Unpaid principal balance of impaired loans with no allowance recorded	289		289		311
Average balance of impaired loans with no allowance recorded	264	295	264	228
Interest income recognized on impaired loans with no allowance recorded	5	5	16	7
Ending balance of impaired loans with allowance recorded	291		291		257
Unpaid principal balance of impaired loans with allowance recorded	318		318		280
Related Allowance	43		43		29
Average balance of impaired loans with allowance recorded	284	223	285	334
Interest income recognized on impaired loans with allowance recorded	3	2	9	13
Impaired Financing Receivable, Recorded Investment	543		543		541
Impaired Financing Receivable, Unpaid Principal Balance	607		607		591
Impaired Financing Receivable, Average Recorded Investment	548	518	549	562
Impaired Financing Receivable, Interest Income, Accrual Method	8	7	25	20
Loans considered impaired due to status as a TDR	408		408		382
Commercial \| Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Ending balance of impaired loans with no allowance recorded	33		33		56
Unpaid principal balance of impaired loans with no allowance recorded	44		44		81
Average balance of impaired loans with no allowance recorded		71		80
Interest income recognized on impaired loans with no allowance recorded		2		6
Ending balance of impaired loans with allowance recorded	47		47
Unpaid principal balance of impaired loans with allowance recorded	52		52
Related Allowance	3		3
Impaired Financing Receivable, Recorded Investment	80		80
Impaired Financing Receivable, Unpaid Principal Balance	96		96
Loans considered impaired due to status as a TDR	68		68		93
Commercial \| Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Average balance of impaired loans with no allowance recorded	36		49
Interest income recognized on impaired loans with no allowance recorded	2		6
Ending balance of impaired loans with allowance recorded					51
Unpaid principal balance of impaired loans with allowance recorded					51
Related Allowance					3
Average balance of impaired loans with allowance recorded	49	41	48	54
Interest income recognized on impaired loans with allowance recorded	1	0	2	1
Impaired Financing Receivable, Recorded Investment					107
Impaired Financing Receivable, Unpaid Principal Balance					132
Impaired Financing Receivable, Average Recorded Investment	85	112	97	134
Impaired Financing Receivable, Interest Income, Accrual Method	3	2	8	7
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	39		39		36
Unpaid principal balance of impaired loans with allowance recorded	43		43		40
Related Allowance	2		2		2
Average balance of impaired loans with allowance recorded	38	33	37	32
Interest income recognized on impaired loans with allowance recorded	1	0	2	2
Impaired Financing Receivable, Recorded Investment	39		39		36
Impaired Financing Receivable, Unpaid Principal Balance	43		43		40
Impaired Financing Receivable, Average Recorded Investment	38	33	37	32
Impaired Financing Receivable, Interest Income, Accrual Method	1	0	2	2
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	325		325		334
Unpaid principal balance of impaired loans with allowance recorded	370		370		385
Related Allowance	6		6		14
Average balance of impaired loans with allowance recorded	326	331	330	327
Interest income recognized on impaired loans with allowance recorded	3	4	11	12
Impaired Financing Receivable, Recorded Investment	325		325		334
Impaired Financing Receivable, Unpaid Principal Balance	370		370		385
Impaired Financing Receivable, Average Recorded Investment	326	331	330	327
Impaired Financing Receivable, Interest Income, Accrual Method	3	4	11	12
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	286		286		308
Unpaid principal balance of impaired loans with allowance recorded	322		322		338
Related Allowance	4		4		4
Average balance of impaired loans with allowance recorded	290	320	299	329
Interest income recognized on impaired loans with allowance recorded	3	3	8	9
Impaired Financing Receivable, Recorded Investment	286		286		308
Impaired Financing Receivable, Unpaid Principal Balance	322		322		338
Impaired Financing Receivable, Average Recorded Investment	290	320	299	329
Impaired Financing Receivable, Interest Income, Accrual Method	3	3	8	9
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	3		3		2
Unpaid principal balance of impaired loans with allowance recorded	3		3		3
Related Allowance	0		0		0
Average balance of impaired loans with allowance recorded	2	1	2	1
Interest income recognized on impaired loans with allowance recorded	0	0	0	0
Impaired Financing Receivable, Recorded Investment	3		3		2
Impaired Financing Receivable, Unpaid Principal Balance	3		3		3
Impaired Financing Receivable, Average Recorded Investment	2	1	2	1
Impaired Financing Receivable, Interest Income, Accrual Method	0	0	0	0
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	8		8		8
Unpaid principal balance of impaired loans with allowance recorded	8		8		8
Related Allowance	3		3		2
Average balance of impaired loans with allowance recorded	9	7	8	7
Interest income recognized on impaired loans with allowance recorded	0	0	0	0
Impaired Financing Receivable, Recorded Investment	8		8		8
Impaired Financing Receivable, Unpaid Principal Balance	8		8		$ 8
Impaired Financing Receivable, Average Recorded Investment	9	7	8	7
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 0	$ 0

LOANS _ LEASES AND ALLOWANCE_11

LOANS / LEASES AND ALLOWANCE FOR CREDIT LOSSES - TDRs (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)contract	Sep. 30, 2018USD ($)contract	Sep. 30, 2017USD ($)contract
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	1,649	2,203	4,993	4,809
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 69	$ 195	$ 465	$ 597
New Troubled Debt Restructuring, Financial effects of modification	1	1	11	11
Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	2	1	6	2
Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	60	185	442	566
Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	7	9	17	22
Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 7
Commercial \| Commercial and Industrial
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	131	277	641	747
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 35	$ 139	$ 302	$ 420
New Troubled Debt Restructuring, Financial effects of modification	0	1	7	9
Commercial \| Commercial \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	1	0	1
Commercial \| Commercial \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	35	138	302	419
Commercial \| Commercial \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Commercial \| Commercial \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
Commercial \| Commercial Real Estate
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	9	28	95	71
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 5	$ 18	$ 79	$ 74
New Troubled Debt Restructuring, Financial effects of modification	0	0	1	1
Commercial \| Commercial Real Estate \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Commercial \| Commercial Real Estate \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	5	18	79	74
Commercial \| Commercial Real Estate \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Commercial \| Commercial Real Estate \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
Consumer \| Automobile
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	848	797	2,088	2,065
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 7	$ 7	$ 17	$ 17
New Troubled Debt Restructuring, Financial effects of modification	0	0	0	(1)
Consumer \| Automobile \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Consumer \| Automobile \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	4	4	11	11
Consumer \| Automobile \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	3	3	6	6
Consumer \| Automobile \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
Consumer \| Home Equity
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	159	247	472	739
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 11	$ 15	$ 29	$ 40
New Troubled Debt Restructuring, Financial effects of modification	1	0	2	1
Consumer \| Home Equity \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	1
Consumer \| Home Equity \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	8	12	21	26
Consumer \| Home Equity \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	3	3	8	9
Consumer \| Home Equity \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 4
Consumer \| Residential Mortgage
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	76	123	278	375
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 9	$ 13	$ 31	$ 40
New Troubled Debt Restructuring, Financial effects of modification	0	0	1	1
Consumer \| Residential Mortgage \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Consumer \| Residential Mortgage \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	8	11	29	31
Consumer \| Residential Mortgage \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	1	2	2	6
Consumer \| Residential Mortgage \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 3
Consumer \| RV and Marine FInance
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	40	32	99	105
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 1	$ 1	$ 2
New Troubled Debt Restructuring, Financial effects of modification	0	0	0	0
Consumer \| RV and Marine FInance \| Interest rate reduction
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Consumer \| RV and Marine FInance \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	1
Consumer \| RV and Marine FInance \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	1	1	1
Consumer \| RV and Marine FInance \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0
Consumer \| Other Consumer
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Number of Contracts \| contract	386	699	1,320	707
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 2	$ 2	$ 6	$ 4
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, Post-modification Outstanding Ending Balance	2	0	6	0
Consumer \| Other Consumer \| Amortization or maturity date change
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	2	0	4
Consumer \| Other Consumer \| Chapter 7 bankruptcy
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	0	0	0	0
Consumer \| Other Consumer \| Other
Financing Receivable, Modifications [Line Items]
New Troubled Debt Restructuring, Post-modification Outstanding Ending Balance	$ 0	$ 0	$ 0	$ 0

AVAILABLE-FOR-SALE SECURITIES -

AVAILABLE-FOR-SALE SECURITIES - Narrative (Details) - USD ($)	3 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Pledged investment securities to secure public and trust deposits, trading account liabilities, US Treasury demand notes and security repurchase agreements	$ 5,000,000,000	$ 6,000,000,000
Other-than-temporary Impairment Loss, Debt Securities, Held-to-maturity, before Tax	$ 0

AVAILABLE-FOR-SALE SECURITIES_2

AVAILABLE-FOR-SALE SECURITIES - Contractual Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	$ 5,085	$ 5,545
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	148	61
Over 12 Months	7,792	6,728
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	416	225
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	12,877	12,273
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(564)	(286)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost	14,279	15,127
Unrealized Gross Gains	12	28
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(564)	(286)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale securities	13,727	14,869
U.S. Treasury
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, Under 1 year	5	5
Amortized Cost	5	5
Unrealized Gross Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	5	5
Available-for-sale securities	5	5
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	2,286	1,660
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	77	19
Over 12 Months	4,632	4,520
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	290	159
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6,918
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(367)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, 1-5 years	0	1
Amortized Cost, 6-10 years	41	90
Amortized Cost, Over 10 years	7,266	6,570
Amortized Cost	7,307	6,661
Unrealized Gross Gains	0	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(367)	(178)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	0	1
Fair Value, 6-10 years	40	89
Fair Value, Over 10 years	6,900	6,394
Available-for-sale securities	6,940	6,484
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	542	1,078
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	23	5
Over 12 Months	70	11
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	612	1,089
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(26)	(5)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, 1-5 years	3	6
Amortized Cost, 6-10 years	30	7
Amortized Cost, Over 10 years	613	1,358
Amortized Cost	646	1,371
Unrealized Gross Gains	0	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(26)	(5)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	3	6
Fair Value, 6-10 years	29	8
Fair Value, Over 10 years	588	1,353
Available-for-sale securities	620	1,367
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	109	960
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	4	15
Over 12 Months	1,594	1,527
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	76	37
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,703	2,487
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(80)	(52)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, 1-5 years	68	23
Amortized Cost, 6-10 years	8	151
Amortized Cost, Over 10 years	1,707	2,365
Amortized Cost	1,783	2,539
Unrealized Gross Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(80)	(52)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	65	22
Fair Value, 6-10 years	8	148
Fair Value, Over 10 years	1,630	2,317
Available-for-sale securities	1,703	2,487
Federal agencies: Mortgage-backed securities
Debt Securities, Available-for-sale [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
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	80	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	2	0
Over 12 Months	72	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	152	39
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(5)	0
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, Under 1 year	1	2
Amortized Cost, 1-5 years	10	9
Amortized Cost, 6-10 years	151	58
Amortized Cost	162	69
Unrealized Gross Gains	0	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(5)	0
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	1	2
Fair Value, 1-5 years	10	9
Fair Value, 6-10 years	146	59
Available-for-sale securities	157	70
Total U.S. Treasury, Federal agency and other agency securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	3,017	3,737
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	106	39
Over 12 Months	6,368	6,058
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	372	196
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	9,385	9,795
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(478)	(235)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost	9,903	10,645
Unrealized Gross Gains	0	3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(478)	(235)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale securities	9,425	10,413
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	1,846	1,681
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	39	21
Over 12 Months	1,278	497
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	38	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,124	2,178
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(77)	(35)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, Under 1 year	211	103
Amortized Cost, 1-5 years	1,156	1,140
Amortized Cost, 6-10 years	1,714	1,709
Amortized Cost, Over 10 years	833	940
Amortized Cost	3,914	3,892
Unrealized Gross Gains	11	21
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(77)	(35)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, Under 1 year	208	103
Fair Value, 1-5 years	1,143	1,134
Fair Value, 6-10 years	1,686	1,704
Fair Value, Over 10 years	811	937
Available-for-sale securities	3,848	3,878
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	157	127
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	3	1
Over 12 Months	146	173
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	6	15
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	303	300
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	(9)	(16)
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, 1-5 years	40	80
Amortized Cost, 6-10 years	41	53
Amortized Cost, Over 10 years	291	349
Amortized Cost	372	482
Unrealized Gross Gains	0	1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(9)	(16)
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Fair Value, 1-5 years	39	80
Fair Value, 6-10 years	41	54
Fair Value, Over 10 years	283	333
Available-for-sale securities	363	467
Corporate debt
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months	65
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	65
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, Under 1 year	1	0
Amortized Cost, 1-5 years	74	73
Amortized Cost, 6-10 years	11	20
Amortized Cost, Over 10 years	0	13
Amortized Cost	86	106
Unrealized Gross Gains	1	3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale, 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
Debt Securities, Available-for-sale [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
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, Amortized Cost [Abstract]
Amortized Cost, Under 1 year	0	1
Amortized Cost, 1-5 years	4	1
Amortized Cost	4	2
Unrealized Gross Gains	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale, 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 SECURITIES_3

AVAILABLE-FOR-SALE SECURITIES - Schedule of Amortized Cost, Fair Value, and Gross Unrealized Gains and Losses (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 14,279	$ 15,127
Unrealized Gross Gains	12	28
Unrealized Gross Losses	(564)	(286)
Fair Value	13,727	14,869
U.S. Treasury
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5	5
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	5	5
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,307	6,661
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(367)	(178)
Fair Value	6,940	6,484
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	646	1,371
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(26)	(5)
Fair Value	620	1,367
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,783	2,539
Unrealized Gross Gains	0	0
Unrealized Gross Losses	(80)	(52)
Fair Value	1,703	2,487
Federal agencies, Other agencies
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	162	69
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(5)	0
Fair Value	157	70
Total U.S. Treasury, Federal agency and other agency securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	9,903	10,645
Unrealized Gross Gains	0	3
Unrealized Gross Losses	(478)	(235)
Fair Value	9,425	10,413
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	3,914	3,892
Unrealized Gross Gains	11	21
Unrealized Gross Losses	(77)	(35)
Fair Value	3,848	3,878
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	372	482
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(9)	(16)
Fair Value	363	467
Corporate debt
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	86	106
Unrealized Gross Gains	1	3
Unrealized Gross Losses	0	0
Fair Value	87	109
Other securities/Sovereign debt
Debt Securities, Available-for-sale [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	Sep. 30, 2018	Dec. 31, 2017
Fair Value
Less than 12 Months	$ 5,085	$ 5,545
Over 12 Months	7,792	6,728
Total	12,877	12,273
Gross Unrealized Losses
Less than 12 Months	(148)	(61)
Over 12 Months	(416)	(225)
Total	(564)	(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	2,286	1,660
Over 12 Months	4,632	4,520
Total	6,918
Gross Unrealized Losses
Less than 12 Months	(77)	(19)
Over 12 Months	(290)	(159)
Total	(367)
Residential Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	542	1,078
Over 12 Months	70	11
Total	612	1,089
Gross Unrealized Losses
Less than 12 Months	(23)	(5)
Over 12 Months	(3)	0
Total	(26)	(5)
Commercial Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	109	960
Over 12 Months	1,594	1,527
Total	1,703	2,487
Gross Unrealized Losses
Less than 12 Months	(4)	(15)
Over 12 Months	(76)	(37)
Total	(80)	(52)
Federal agencies, Other agencies
Fair Value
Less than 12 Months	80	39
Over 12 Months	72	0
Total	152	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	3,017	3,737
Over 12 Months	6,368	6,058
Total	9,385	9,795
Gross Unrealized Losses
Less than 12 Months	(106)	(39)
Over 12 Months	(372)	(196)
Total	(478)	(235)
Municipal securities
Fair Value
Less than 12 Months	1,846	1,681
Over 12 Months	1,278	497
Total	3,124	2,178
Gross Unrealized Losses
Less than 12 Months	(39)	(21)
Over 12 Months	(38)	(14)
Total	(77)	(35)
Asset-backed securities
Fair Value
Less than 12 Months	157	127
Over 12 Months	146	173
Total	303	300
Gross Unrealized Losses
Less than 12 Months	(3)	(1)
Over 12 Months	(6)	(15)
Total	(9)	$ (16)
Corporate debt
Fair Value
Less than 12 Months	65
Over 12 Months	0
Total	65
Gross Unrealized Losses
Less than 12 Months	0
Over 12 Months	0
Total	0
Other securities/Sovereign debt
Fair Value
Less than 12 Months	0
Over 12 Months	0
Total	0
Gross Unrealized Losses
Less than 12 Months	0
Over 12 Months	0
Total	$ 0

AVAILABLE-FOR-SALE SECURITIES_4

AVAILABLE-FOR-SALE SECURITIES AVAILABLE-FOR-SALE SECURITIES - Gross Realized Gains (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Gross gains on sales of securities	$ 0	$ 4	$ 6	$ 8
Gross (losses) on sales of securities	2	4	8	4
Net (loss) gain on sales of securities	(2)	0	(2)	4
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0	0	0	(4)
Gain (Loss) on Sale of Investments	$ (2)	$ 0	$ (2)	$ 0

HELD-TO-MATURITY SECURITIES - N

HELD-TO-MATURITY SECURITIES - Narrative (Details)	3 Months Ended
HELD-TO-MATURITY SECURITIES - Narrative (Details)	Sep. 30, 2018USD ($)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Other-than-temporary Impairment Loss, Debt Securities, Held-to-maturity, before Tax	$ 0

HELD-TO-MATURITY SECURITIES - C

HELD-TO-MATURITY SECURITIES - Contractual Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Amortized Cost	$ 8,465	$ 9,091
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Fair Value	8,112	8,971
Collateralized Mortgage Obligations [Member]
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held-to-maturity Securities, 6-10 years	36	0
Held-to-maturity Securities, Over 10 years	2,167	3,714
Amortized Cost	2,203	3,714
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Fair Value, 6-10 years	35	0
Fair Value, Over 10 years	2,073	3,657
Fair Value	2,108	3,657
Residential Mortgage Backed Securities [Member]
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held-to-maturity Securities, 6-10 years	0	28
Held-to-maturity Securities, Over 10 years	1,624	1,021
Amortized Cost	1,624	1,049
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Fair Value, 6-10 years	0	28
Fair Value, Over 10 years	1,555	1,016
Fair Value	1,555	1,044
Commercial Mortgage Backed Securities [Member]
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [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	4,141	3,752
Amortized Cost	4,271	3,791
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Fair Value, 1-5 years	0	37
Fair Value, 6-10 years	126	1
Fair Value, Over 10 years	3,968	3,698
Fair Value	4,094	3,736
Federal agencies, Other agencies
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held-to-maturity Securities, 1-5 years	12	7
Held-to-maturity Securities, 6-10 years	204	362
Held-to-maturity Securities, Over 10 years	146	163
Amortized Cost	362	532
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Fair Value, 1-5 years	12	8
Fair Value, 6-10 years	197	360
Fair Value, Over 10 years	141	161
Fair Value	350	529
Total U.S. Treasury, Federal agency and other agency securities
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Amortized Cost	8,460	9,086
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Fair Value	8,107	8,966
Municipal securities
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held-to-maturity Securities, Over 10 years	5	5
Amortized Cost	5	5
Debt Securities, Held-to-maturity, Maturity, Fair Value [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	Sep. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 8,465	$ 9,091
Unrealized Gross Gains	0	4
Unrealized Gross Losses	(353)	(124)
Fair Value	8,112	8,971
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,203	3,714
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(95)	(58)
Fair Value	2,108	3,657
Residential Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,624	1,049
Unrealized Gross Gains	0	2
Unrealized Gross Losses	(69)	(7)
Fair Value	1,555	1,044
Commercial Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	4,271	3,791
Unrealized Gross Gains	0	0
Unrealized Gross Losses	(177)	(55)
Fair Value	4,094	3,736
Federal agencies, Other agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	362	532
Unrealized Gross Gains	0	1
Unrealized Gross Losses	(12)	(4)
Fair Value	350	529
Total U.S. Treasury, Federal agency and other agency securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	8,460	9,086
Unrealized Gross Gains	0	4
Unrealized Gross Losses	(353)	(124)
Fair Value	8,107	8,966
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	5	5
Unrealized Gross Gains	0	0
Unrealized Gross Losses	0	0
Fair Value	$ 5	$ 5

HELD-TO-MATURITY SECURITIES -_2

HELD-TO-MATURITY SECURITIES - Continuous Unrealized Loss Position (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fair Value
Less than 12 Months	$ 1,966	$ 7,048
Over 12 Months	6,124	1,416
Total	8,090	8,464
Gross Unrealized Losses
Less than 12 Months	(75)	(84)
Over 12 Months	(278)	(40)
Total	(353)	(124)
Collateralized Mortgage Obligations [Member]
Fair Value
Less than 12 Months	557	2,369
Over 12 Months	1,551	1,019
Total	2,108	3,388
Gross Unrealized Losses
Less than 12 Months	(21)	(26)
Over 12 Months	(74)	(32)
Total	(95)	(58)
Residential Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	807	974
Over 12 Months	748	0
Total	1,555	974
Gross Unrealized Losses
Less than 12 Months	(33)	(7)
Over 12 Months	(36)	0
Total	(69)	(7)
Commercial Mortgage Backed Securities [Member]
Fair Value
Less than 12 Months	410	3,456
Over 12 Months	3,683	253
Total	4,093	3,709
Gross Unrealized Losses
Less than 12 Months	(15)	(49)
Over 12 Months	(162)	(6)
Total	(177)	(55)
Federal agencies, Other agencies
Fair Value
Less than 12 Months	192	249
Over 12 Months	138	139
Total	330	388
Gross Unrealized Losses
Less than 12 Months	(6)	(2)
Over 12 Months	(6)	(2)
Total	(12)	(4)
Total U.S. Treasury, Federal agency and other agency securities
Fair Value
Less than 12 Months	1,966	7,048
Over 12 Months	6,120	1,411
Total	8,086	8,459
Gross Unrealized Losses
Less than 12 Months	(75)	(84)
Over 12 Months	(278)	(40)
Total	(353)	(124)
Municipal securities
Fair Value
Less than 12 Months	0	0
Over 12 Months	4	5
Total	4	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	Sep. 30, 2018	Dec. 31, 2017
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	$ 564	$ 600
Other securities	565	600
Mutual Fund
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	20	18
Other securities	20	18
Marketable equity securities
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	1	1
Other securities	2	1
Investment in Federal Home Loan Bank Stock \| Nonmarketable equity securities
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	248	287
Other securities	248	287
Investment in Federal Reserve Stock \| Nonmarketable equity securities
Schedule of Other Securities [Line Items]
Other Securities, Amortized Cost Basis	295	294
Other securities	$ 295	$ 294

LOAN SALES AND SECURITIZATION_2

LOAN SALES AND SECURITIZATIONS - Narrative (Details) - Residential Mortgage - USD ($) $ in Millions	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Servicing Assets at Fair Value [Line Items]
Servicing income	$ 15	$ 14	$ 44	$ 42
Unpaid principal balance of third party serviced loans	$ 20,600		$ 20,600	$ 19,800

LOAN SALES AND SECURITIZATION_3

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio (Details) - Commercial Loan [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Servicing Asset at Amortized Cost [Line Items]
Loans sold with servicing retained	$ 1,047	$ 1,179	$ 2,787	$ 2,824
Pretax gains resulting from above loan sales	$ 24	$ 27	$ 64	$ 66

LOAN SALES AND SECURITIZATION_4

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Fair Value Method (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Residential Mortgage
Servicing Asset at Fair Value, Amount [Roll Forward]
Fair value, end of period:	$ 11	$ 12

LOAN SALES AND SECURITIZATION_5

LOAN SALES AND SECURITIZATIONS - Residential Mortgage Portfolio, MSRs Amortization Method (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 251		$ 251		$ 238
Residential Mortgage
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Carrying value, beginning of period	204	$ 176	191	$ 172
New servicing assets created	12	13	32	31
Impairment recovery (charge)	0	(1)	(7)	0
Amortization and other	(8)	(7)	(22)	(20)
Carrying value, end of period	208	183	208	183
Fair value, end of period	$ 222	$ 184	$ 222	$ 184
Residential Mortgage \| Amortization method
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Weighted-average life (years)	7 years 1 month	7 years	7 years 1 month	7 years

LOAN SALES AND SECURITIZATION_6

LOAN SALES AND SECURITIZATIONS LOAN SALES AND SECURTIZIATIONS - Residential Mortgage Portfolio, MSRs Fair Value Method Key Assumptions (Details)	3 Months Ended	12 Months Ended
	Sep. 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 SECURITIZATION_7

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
	Sep. 30, 2018	Dec. 31, 2017
Servicing Asset at Amortized Cost [Line Items]
Constant prepayment rate (annualized), actual	8.10%	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	9.41%	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 SECURITIZATION_8

LOAN SALES AND SECURITIZATIONS - Automobile Loans, MSRs Amortization Method (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 251	$ 238

LOAN SALES AND SECURITIZATION_9

LOAN SALES AND SECURITIZATIONS - Small Business Association Portfolio, MSRs Amortization Method (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Fair value, end of period	$ 251	$ 238

LONG-TERM DEBT (Details)

LONG-TERM DEBT (Details) - Senior Notes - USD ($)	9 Months Ended
LONG-TERM DEBT (Details) - Senior Notes - USD ($)	Sep. 30, 2018	Aug. 16, 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
Huntington National Bank Senior Note Due October 2023, 3.55 Percent [Domain]
Debt Instrument [Line Items]
Debt face amount		$ 750,000,000
Debt percent of value		99.78%
Debt stated interest rate		3.55%
Debt Instrument, Redemption Price, Percentage	100.00%
Debt Issuance Costs, Gross	$ 4,000,000

OTHER COMPREHENSIVE INCOME - Ac

OTHER COMPREHENSIVE INCOME - Activity (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pretax
Other comprehensive income (loss), pretax	$ (77)	$ (29)	$ (334)	$ 48
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	16	10	73	(17)
After-tax
Other comprehensive income (loss), net of tax	(61)	(19)	(261)	31
Accumulated OTTI
Pretax
Other comprehensive income (loss), pretax	0	0	0	3
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	0	0	0	(1)
After-tax
Other comprehensive income (loss), net of tax	0	0	0	2
Unrealized gains and (losses) on debt securities \| Debt Securities
Pretax
Other comprehensive income (loss), before reclassifications, before tax	(82)	(42)	(359)	20
Reclassification adjustment, before tax	3	9	21	19
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	18	15	78	(7)
Reclassification adjustment, tax	(1)	(4)	(4)	(7)
After-tax
Other comprehensive income (loss), before reclassifications, net of tax	(64)	(27)	(281)	13
Reclassification adjustment, net of tax	2	5	17	12
Other comprehensive income (loss), net of tax	(62)	(22)	(264)	27
Unrealized gains and (losses) on debt securities and Accumulated OTTI \| Debt Securities
Pretax
Other comprehensive income (loss), pretax	(79)	(33)	(338)	42
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	17	11	74	(15)
Unrealized gains and (losses) on cash flow hedging derivatives
Pretax
Other comprehensive income (loss), before reclassifications, before tax		2		2
Reclassification adjustment, before tax		0		1
Other comprehensive income (loss), pretax		2		3
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax		0		0
Reclassification adjustment, tax		0		(1)
Total other comprehensive income (loss), tax (expense) benefit		0		(1)
After-tax
Other comprehensive income (loss), before reclassifications, net of tax		2		2
Reclassification adjustment, net of tax		0		0
Other comprehensive income (loss), net of tax		2		2
Unrealized gains (losses) for pension and other post- retirement obligations
Pretax
Other comprehensive income (loss), pretax	2	2	4	3
Tax (Expense) Benefit
Total other comprehensive income (loss), tax (expense) benefit	(1)	(1)	(1)	(1)
After-tax
Other comprehensive income (loss), net of tax	$ 1	$ 1	$ 3	$ 2

OTHER COMPREHENSIVE INCOME OTHE

OTHER COMPREHENSIVE INCOME OTHER COMPREHENSIVE INCOME - AOCI Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			$ 10,814	$ 10,308	$ 10,308
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 1		1
Other comprehensive income before reclassifications			(281)	17
Amounts reclassified from accumulated OCI to earnings			20	14
Period change			(261)	31
Balance, end of period	10,934	$ 10,699	10,934	10,699	10,814
Unrealized gains and (losses) on debt securities \| Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(278)	(193)	(193)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					(1)
Other comprehensive income before reclassifications			(281)	15
Amounts reclassified from accumulated OCI to earnings			17	12
Period change			(264)	27
Balance, end of period	(543)	(166)	(543)	(166)	(278)
Unrealized gains and (losses) on cash flow hedging derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			0	(3)	(3)
Other comprehensive income before reclassifications			0	2
Amounts reclassified from accumulated OCI to earnings			0	0
Period change			0	2
Balance, end of period	0	(1)	0	(1)	0
Unrealized gains (losses) for pension and other post- retirement obligations
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(250)	(205)	(205)
Other comprehensive income before reclassifications			0	0
Amounts reclassified from accumulated OCI to earnings			3	2
Period change			3	2
Balance, end of period	(247)	(203)	(247)	(203)	(250)
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(528)	(401)	(401)
Balance, end of period	(790)	(370)	$ (790)	$ (370)	(528)
Reclassification out of Accumulated Other Comprehensive Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Net unrealized loss on securities transfer	$ (141)	$ 97			$ (95)

OTHER COMPREHENSIVE INCOME - Re

OTHER COMPREHENSIVE INCOME - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest income - held-to-maturity securities - taxable	$ 52	$ 49	$ 159	$ 138
Noninterest income - net gains (losses) on sale of securities	(2)	0	(2)	4
Interest income - loans and leases	848	724	2,414	2,100
Noninterest income - other income	44	42	131	138
Noninterest expense - personnel costs	(388)	(377)	(1,160)	(1,151)
Income before income taxes	440	365	1,237	982
Provision for income taxes	(62)	(90)	(178)	(228)
Net income applicable to common shares	360	256	1,008	697
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)	(1)	(9)	(7)
Noninterest income - net gains (losses) on sale of securities	0	(8)	(12)	(8)
Accumulated OTTI \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Noninterest income - net gains (losses) on sale of securities	0	0	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)	(9)	(21)	(19)
Provision for income taxes	1	4	4	7
Net income applicable to common shares	(2)	(5)	(17)	(12)
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	1
Net income applicable to common shares			0	0
Amortization of defined benefit pension and post-retirement items: actuarial gains (losses) \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Noninterest expense - personnel costs	(2)	(1)	(6)	(4)
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)	2	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	(2)	(2)	(4)	(3)
Provision for income taxes	1	1	1	1
Net income applicable to common shares	$ (1)	$ (1)	$ (3)	$ (2)

SHAREHOLDERS' EQUITY (Details)

SHAREHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Sep. 30, 2018	Feb. 27, 2018	Feb. 22, 2018	Dec. 31, 2017
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding	740,500			1,098,006
Preferred Stock, Value, Outstanding	$ 1,203
Preferred stock	$ 1,203			$ 1,071
Series A Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred stock, dividend payment rate, variable	0.085
Series B Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding	35,500
Preferred Stock, Value, Outstanding	$ 23
Preferred stock, dividend payment rate, variable	3-mo. LIBOR + 270 bps
Preferred Stock, Redemption Date	Jan. 15, 2017
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
Preferred Stock, Value, Outstanding	$ 100
Preferred stock, dividend payment rate, variable	0.05875
Preferred Stock, Redemption Date	Jan. 15, 2022
Series E Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share		$ 100,000
Depositary Shares, Liquidation Preference Per Share		$ 1,000
Preferred Stock, Shares Outstanding	5,000
Preferred Stock, Value, Outstanding	$ 495
Preferred stock, dividend payment rate, variable	0.057
Preferred stock		$ 500
Depositary Shares, Issued	500,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Payments of Stock Issuance Costs	$ 5
Preferred Stock, Redemption Date	Apr. 15, 2023
Series D Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding	400,000
Preferred Stock, Value, Outstanding	$ 386
Preferred stock, dividend payment rate, variable	0.0625
Preferred Stock, Redemption Date	Jul. 15, 2021
Series D Preferred Stock2
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Shares Outstanding	200,000
Preferred Stock, Value, Outstanding	$ 199
Preferred stock, dividend payment rate, variable	0.0625
Preferred Stock, Redemption Date	Jul. 15, 2021

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Feb. 22, 2018
Basic earnings per common share:
Net income	$ 378	$ 275	$ 1,059	$ 754
Preferred stock dividends	(18)	(19)	(51)	(57)
Net income available to common shareholders	360	256	1,008	697
Effect of assumed preferred stock conversion	0	0	0	0
Net income applicable to diluted earnings per share	$ 360	$ 256	$ 1,008	$ 697
Average common shares issued and outstanding (in shares)	1,084,536,000	1,086,038,000	1,090,570,000	1,087,115,000
Basic earnings per common share (in usd per share)	$ 0.33	$ 0.24	$ 0.92	$ 0.64
Dilutive potential common shares:
Stock options and restricted stock units and awards	15,655,000	17,079,000	17,105,000	17,515,000
Shares held in deferred compensation plans	3,549,000	3,228,000	3,416,000	3,096,000
Dilutive impact of Preferred Stock	0	0	5,887,000	0
Other	0	146,000	0	152,000
Dilutive potential common shares	19,204,000	20,453,000	26,408,000	20,763,000
Total diluted average common shares issued and outstanding (in shares)	1,103,740,000	1,106,491,000	1,116,978,000	1,107,878,000
Diluted earnings per common share (in usd per share)	$ 0.33	$ 0.23	$ 0.90	$ 0.63
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Options outstanding to purchase common stock shares having antidilutive effect	1,600,000	1,500,000	2,000,000	900,000
Series A Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Preferred stock, dividend payment rate, variable	0.085
Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issued upon conversion of convertible preferred stock (in shares)					30,300,000

NON-INTEREST INCOME - Summary o

NON-INTEREST INCOME - Summary of Noninterest Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue from Contract with Customer [Abstract]
Noninterest income from contracts with customers	$ 223		$ 654
Noninterest income within the scope of other GAAP topics	119		338
Total noninterest income	$ 342	$ 330	$ 992	$ 967

NON-INTEREST INCOME - Disaggreg

NON-INTEREST INCOME - Disaggregation by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	$ 223		$ 654
Noninterest income within the scope of other GAAP topics	119		338
Noninterest income	342	$ 330	992	$ 967
Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	93		270
Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	53		154
Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	42		128
Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	19		61
Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	16		41
Operating Segments \| Consumer And Business Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	150		436
Noninterest income within the scope of other GAAP topics	42		117
Noninterest income	192	189	553	544
Operating Segments \| Consumer And Business Banking [Member] \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	75		215
Operating Segments \| Consumer And Business Banking [Member] \| Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	50		146
Operating Segments \| Consumer And Business Banking [Member] \| Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	7		19
Operating Segments \| Consumer And Business Banking [Member] \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	8		26
Operating Segments \| Consumer And Business Banking [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	10		30
Operating Segments \| Commercial Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	23		65
Noninterest income within the scope of other GAAP topics	56		163
Noninterest income	79	67	228	201
Operating Segments \| Commercial Banking [Member] \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	16		48
Operating Segments \| Commercial Banking [Member] \| Cards and payment processing income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	3		8
Operating Segments \| Commercial Banking [Member] \| Trust and investment management services
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1		3
Operating Segments \| Commercial Banking [Member] \| Insurance income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1		3
Operating Segments \| Commercial Banking [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2		3
Operating Segments \| Vehicle Finance [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2		6
Noninterest income within the scope of other GAAP topics	0		2
Noninterest income	2	3	8	11
Operating Segments \| Vehicle Finance [Member] \| Service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1		4
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	1		2
Operating Segments \| Regional Banking and The Huntington Private Client Group [Member]
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	47		144
Noninterest income within the scope of other GAAP topics	0		1
Noninterest income	47	46	145	141
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		3
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	34		106
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		31
Operating Segments \| Regional Banking and The Huntington Private Client Group [Member] \| Other income
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	2		4
Treasury / Other
Disaggregation of Revenue [Line Items]
Noninterest income from contracts with customers	1		3
Noninterest income within the scope of other GAAP topics	21		55
Noninterest income	22	$ 25	58	$ 70
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	$ 1		$ 2

BENEFIT PLANS - Narrative (Deta

BENEFIT PLANS - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
BENEFIT PLANS - Narrative (Details) $ in Millions	Sep. 30, 2018USD ($)year	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
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%.
Defined Contribution Plan, Cost \| $	$ 7	$ 5	$ 35	$ 26
Post Retirement Benefits
Benefit Plans (Textuals) [Abstract]
Employees retirement age for health care and life insurance benefits under unfunded defined benefit post-retirement plan \| year	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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits
Components of net periodic benefit expense [Abstract]
Service cost	$ 0	$ 0	$ 2	$ 2
Interest cost	9	8	23	22
Expected return on plan assets	(12)	(13)	(36)	(41)
Amortization of prior service cost	0	0	0	0
Amortization of gain (loss)	2	1	6	5
Settlements	1	4	6	10
Net periodic (benefit) cost	0	0	1	(2)
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	(1)	0	(2)	(1)
Amortization of gain (loss)	0	0	0	0
Settlements	0	0	0	0
Net periodic (benefit) cost	$ (1)	$ 0	$ (2)	$ (1)

FAIR VALUES OF ASSETS AND LIA_3

FAIR VALUES OF ASSETS AND LIABILITIES - Narrative (Details) - USD ($) $ in Millions	Sep. 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	$ 727	$ 413
Loans Receivable, Fair Value Disclosure	$ 81	$ 93

FAIR VALUES OF ASSETS AND LIA_4

FAIR VALUES OF ASSETS AND LIABILITIES - Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets measured at fair value on a recurring basis
Trading account securities	$ 83	$ 86
Available-for-sale securities	13,727	14,869
Other securities	565	600
Loans Held-for-sale, Fair Value Disclosure	727	413
Consumer loans	81	93
Gross amounts of recognized assets	498	322
Derivative assets netting	(318)	(190)
Net amounts of assets presented in the condensed consolidated balance sheets	180	132
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	441	331
Gross amounts offset in the condensed consolidated balance sheets	(221)	(245)
Derivative liabilities	220	86
Municipal securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	3,848	3,878
U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	5	5
Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	620	1,367
Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,703	2,487
Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	157	70
Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	363	467
Corporate debt
Assets measured at fair value on a recurring basis
Available-for-sale securities	87	109
Fair Value, Measurements, Recurring
Assets measured at fair value on a recurring basis
Trading account securities	83	86
Available-for-sale securities	13,727	14,869
Other securities	22	19
Loans Held-for-sale, Fair Value Disclosure	727	413
MSRs	11	11
Derivative assets netting	(318)	(190)
Net amounts of assets presented in the condensed consolidated balance sheets	180	132
Liabilities measured at fair value on a recurring basis
Gross amounts offset in the condensed consolidated balance sheets	(221)	(245)
Derivative liabilities	220	86
Fair Value, Measurements, Recurring \| Municipal securities
Assets measured at fair value on a recurring basis
Trading account securities	5
Available-for-sale securities	3,848	3,878
Fair Value, Measurements, Recurring \| Other securities
Assets measured at fair value on a recurring basis
Trading account securities	78	86
Available-for-sale securities	4	2
Fair Value, Measurements, Recurring \| U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	5	5
Fair Value, Measurements, Recurring \| Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	6,940	6,484
Fair Value, Measurements, Recurring \| Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	620	1,367
Fair Value, Measurements, Recurring \| Commercial Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	1,703	2,487
Fair Value, Measurements, Recurring \| Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	157	70
Fair Value, Measurements, Recurring \| Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	363	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 \| Level 1
Assets measured at fair value on a recurring basis
Trading account securities	77	83
Available-for-sale securities	5	5
Other securities	22	19
Loans Held-for-sale, Fair Value Disclosure	0	0
Consumer loans	0	0
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 \| 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 \| Other securities
Assets measured at fair value on a recurring basis
Trading account securities	77	83
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring \| Level 1 \| U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	5	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 \| 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 2
Assets measured at fair value on a recurring basis
Trading account securities	6	3
Available-for-sale securities	10,445	11,673
Loans Held-for-sale, Fair Value Disclosure	727	413
Consumer loans	49	55
MSRs	0	0
Gross amounts of recognized assets	493	316
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	437	326
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	571	711
Fair Value, Measurements, Recurring \| Level 2 \| Other securities
Assets measured at fair value on a recurring basis
Trading account securities	1	3
Available-for-sale securities	4	2
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	6,940	6,484
Fair Value, Measurements, Recurring \| Level 2 \| Residential Mortgage Backed Securities [Member]
Assets measured at fair value on a recurring basis
Available-for-sale securities	620	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	1,703	2,487
Fair Value, Measurements, Recurring \| Level 2 \| Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	157	70
Fair Value, Measurements, Recurring \| Level 2 \| Asset-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	363	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 3
Assets measured at fair value on a recurring basis
Trading account securities	0	0
Available-for-sale securities	3,277	3,191
Loans Held-for-sale, Fair Value Disclosure	0	0
Consumer loans	32	38
MSRs	11	11
Gross amounts of recognized assets	5	6
Liabilities measured at fair value on a recurring basis
Gross amounts of recognized liabilities	4	5
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	3,277	3,167
Fair Value, Measurements, Recurring \| Level 3 \| Other securities
Assets measured at fair value on a recurring basis
Trading account securities	0	0
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| U.S. Treasury
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Federal agencies: Mortgage-backed securities
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| Federal agencies, Other agencies
Assets measured at fair value on a recurring basis
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring \| Level 3 \| 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 VALUES OF ASSETS AND LIA_5

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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	13,727		13,727		14,869
Assets Level 3 Roll Forward:
Transfers out of Level 3 (1)			(26)	(4)
Total gains/losses for the period:
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings			25	9
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			3	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Change in Unrealized Gain (Loss)			(1)	(9)
MSRs
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance	11	13	11	14	14
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	0	(1)	0	(2)
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	12	11	12	11
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date	0	(1)	0	(2)
Derivative instruments
Assets Level 3 Roll Forward:
Opening balance	1	3
Transfers out of Level 3 (1)	(12)	(1)
Total gains/losses for the period:
Included in earnings	(9)	(1)
Included in OCI	0	0
Purchases/originations	0	0
Sales	0	0
Repayments	0	0	0	0
Settlements	(3)	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	(3)	(1)
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 out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance	3,178	2,872	3,167	2,798	2,798
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	(1)	(1)	(3)	(4)
Included in OCI	0	34	(37)	(1)
Purchases/originations	260	167	539	414
Sales	0	0	0	0
Repayments	0	0	0	0
Settlements	(160)	(46)	(389)	(249)
Closing balance	3,277	2,958	3,277	2,958	3,167
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
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 out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance		43	24	76	76
Transfers out of Level 3 (1)		0
Total gains/losses for the period:
Included in earnings		(2)	(2)	(5)
Included in OCI		(5)	(11)	(13)
Purchases/originations		0	0	0
Sales		(22)	(33)	(59)
Repayments		0	0	0
Settlements		0	0	(1)
Closing balance	0	24	0	24	24
Change in unrealized gains or losses for the period included in earnings for assets held at end of the reporting date		0	0	(4)
Automobile
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3			0	0
Assets Level 3 Roll Forward:
Opening balance	34	44	38	48	48
Transfers out of Level 3 (1)	0	0
Total gains/losses for the period:
Included in earnings	0	0	0	(1)
Included in OCI	0	0	0	0
Purchases/originations	0	0	0	0
Sales	0	0	0	0
Repayments	(2)	(4)	(6)	(9)
Settlements	0	0	0	0
Closing balance	32	40	32	40	38
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	1,703		1,703		2,487
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	620		620		1,367
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Available-for-sale securities	13,727		13,727		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	1,703		1,703		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	620		620		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	10,445		10,445		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	1,703		1,703		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	$ 620		$ 620		$ 1,367

FAIR VALUES OF ASSETS AND LIA_6

FAIR VALUES OF ASSETS AND LIABILITIES - Level 3 Classification of Gains/Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 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			$ 25	$ 9
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)	0	(2)
Mortgage banking income	0	1
Securities gains (losses)		0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	0	(1)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee income		0
Derivative Financial Instruments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Mortgage banking income	(9)	(1)
Securities gains (losses)		0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	(9)	(1)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee 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)	(3)	(4)
Mortgage banking income	0	0
Securities gains (losses)		0
Other expense	(1)		(3)
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 Interest and fee income		(1)
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)	(2)	(5)
Mortgage banking income		0
Securities gains (losses)		(2)
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings		(2)
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee 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	0	0	(1)
Mortgage banking income	0	0
Securities gains (losses)		0
Other expense	0
Fair Value, Assets and Liabilities Measured on Recurring Basis, Gain (Loss) Included in Earnings	$ 0	0
Fair Value Assets Measured On Recurring Basis Gain Loss Included In Interest and fee income		$ 0
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			25	9
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	(2)
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	0
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)	(5)
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				$ (1)
Interest and Fee 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					$ 0
Interest and Fee 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
Interest and Fee 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					(4)
Interest and Fee 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
Interest and Fee 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

FAIR VALUES OF ASSETS AND LIA_7

FAIR VALUES OF ASSETS AND LIABILITIES - Fair Value Option (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	$ 727	$ 413
Loans Receivable, Fair Value Disclosure	81	93
Fair Value, Measurements, Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	727	413
Fair Value, Measurements, Recurring \| Mortgages Held For Sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Held-for-sale, Fair Value Disclosure	727	413
Loans Held For Sale Unpaid Principal	713	400
Difference	(14)	(13)
Fair Value, Measurements, Recurring \| Mortgages Held To Maturity
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans Receivable, Fair Value Disclosure	81	93
Loans Held To Maturity Unpaid Principal	88	102
Difference	(7)	(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	6	10
Loans Held To Maturity Unpaid Principal	7	11
Difference	$ (1)	$ (1)

FAIR VALUES OF ASSETS AND LIA_8

FAIR VALUES OF ASSETS AND LIABILITIES - Fair Value Option-Changs in Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Measurements, Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) from fair value changes	$ (4)	$ (2)	$ (1)	$ (12)
Consumer loans
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) from fair value changes	$ 0	$ 0	$ 0	$ (1)

FAIR VALUES OF ASSETS AND LIA_9

FAIR VALUES OF ASSETS AND LIABILITIES - Non-Recurring Basis (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI		$ 83	$ 86
Loans held for sale	[1]	792	488
Available-for-sale securities		13,727	14,869
Long-term debt		9,385	9,206
Held-to-maturity securities		8,465	9,091
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		72,609	69,426
Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI		83	86
Loans held for sale		795	491
Available-for-sale securities		13,727	14,869
Long-term debt		9,523	9,402
Held-to-maturity securities		8,112	8,971
Other Securities		565	600
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		71,918	69,146
Level 1 \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI		77
Loans held for sale		0	0
Available-for-sale securities		5	5
Long-term debt		0	0
Held-to-maturity securities		0	0
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		0	0
Level 2 \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI		6
Loans held for sale		727	413
Available-for-sale securities		10,445	11,673
Long-term debt		8,986	8,944
Held-to-maturity securities		8,112	8,971
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		49	0
Level 3 \| Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI		0	0
Loans held for sale		68	78
Available-for-sale securities		3,277	3,191
Long-term debt		537	458
Held-to-maturity securities		0	0
Assets measured at fair value on a nonrecurring basis
Net loans and direct financing leases		71,869	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		(53)
Other real estate owned		(27)
Nonrecurring Basis \| Total Gains/(Losses)
Assets measured at fair value on a nonrecurring basis
Impaired loans		(1)
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		(53)
Other real estate owned		$ (27)

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

FAIR VALUES OF ASSETS AND LI_10

FAIR VALUES OF ASSETS AND LIABILITIES - Significant Unobservable Level 3 Inputs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Gross amounts of recognized assets	$ 498	$ 322
Derivative Liability, Fair Value, Gross Liability	441	331
Available-for-sale securities	13,727	14,869
Consumer loans	81	93
Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
MSRs	11	11
Available-for-sale securities	13,727	14,869
Fair Value, Measurements, Recurring \| Level 3
Fair Value Disclosures [Abstract]
MSRs	11	11
Gross amounts of recognized assets	5	6
Derivative Liability, Fair Value, Gross Liability	4	5
Available-for-sale securities	3,277	3,191
Consumer loans	32	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	363	467
Asset-backed securities \| Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
Available-for-sale securities	363	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	3,848	3,878
Municipal securities \| Fair Value, Measurements, Recurring
Fair Value Disclosures [Abstract]
Available-for-sale securities	3,848	3,878
Municipal securities \| Fair Value, Measurements, Recurring \| Level 3
Fair Value Disclosures [Abstract]
Available-for-sale securities	$ 3,277	$ 3,167
Cost Approach Valuation Technique \| Maximum \| Fair Value, Measurements, Recurring \| MSRs \| Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	54.00%	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	4.00%	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	9.00%	22.00%
Discount rate	7.00%	18.00%
Cost Approach Valuation Technique \| Maximum \| Fair Value, Measurements, Nonrecurring \| MSRs \| Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	21.00%
Spread over forward interest rate swap rates	0	0.2
Cost Approach Valuation Technique \| Minimum \| Fair Value, Measurements, Recurring \| MSRs \| Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	6.00%	8.00%
Spread over forward interest rate swap rates	0.05	0.08
Cost Approach Valuation Technique \| Minimum \| Fair Value, Measurements, Recurring \| Private label CMO \| Level 3
Fair Value Disclosures [Abstract]
Discount rate	3.00%	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	9.00%	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	3.00%	4.00%
Cumulative default	4.00%	3.00%
Loss given default	25.00%	24.00%
Cost Approach Valuation Technique \| Weighted Average \| Fair Value, Measurements, Recurring \| Asset-backed securities \| Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	0.00%	7.00%
Discount rate	0.00%	7.00%
Cumulative default	0.00%	7.00%
Loss given default	0.00%	98.00%
Cure given deferral	0.00%	50.00%
Cost Approach Valuation Technique \| Weighted Average \| Fair Value, Measurements, Recurring \| Loans held for investment \| Level 3
Fair Value Disclosures [Abstract]
Constant prepayment rate	9.00%	9.00%
Discount rate	7.00%	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	(4.00%)	(5.00%)
Estimated Pull through %	3.00%	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 \| Level 3
Fair Value Disclosures [Abstract]
Fair Value Inputs, Timing of the resolution of the litigation	Jun. 30, 2020
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

FAIR VALUES OF ASSETS AND LI_11

FAIR VALUES OF ASSETS AND LIABILITIES - Balance Sheet Location (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Financial Assets:
Trading account securities		$ 83	$ 86
Available-for-sale securities		13,727	14,869
Held-to-maturity securities		8,465	9,091
Loans held for sale	[1]	792	488
Net loans and direct financing leases		72,609	69,426
Derivatives		180	132
Financial Liabilities:
Deposits		81,689	77,041
Short-term borrowings		1,348	5,056
Long-term borrowings		9,385	9,206
Derivatives		220	86
Reported Value Measurement [Member]
Financial Assets:
Cash and short term assets			1,567
Trading account securities		83	86
Available-for-sale securities		13,727	14,869
Held-to-maturity securities		8,465
Other Securities		565	600
Loans held for sale		792
Net loans and direct financing leases			69,426
Derivatives			132
Financial Liabilities:
Deposits		81,689	77,041
Short-term borrowings		1,348	5,056
Long-term borrowings		9,385	9,206
Derivatives		220	86
Estimate of Fair Value Measurement [Member]
Financial Assets:
Cash and short term assets		1,342
Trading account securities		83	86
Available-for-sale securities		13,727	14,869
Held-to-maturity securities		8,112	8,971
Other Securities		565	600
Loans held for sale		795	491
Other securities		22	19
Net loans and direct financing leases		71,918	69,146
Derivatives			132
Financial Liabilities:
Deposits		81,631	77,010
Short-term borrowings		1,348	5,056
Long-term borrowings		9,523	9,402
Estimate of Fair Value Measurement [Member] \| Level 1
Financial Assets:
Trading account securities		77
Available-for-sale securities		5	5
Held-to-maturity securities		0	0
Loans held for sale		0	0
Other securities		22	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		6
Available-for-sale securities		10,445	11,673
Held-to-maturity securities		8,112	8,971
Loans held for sale		727	413
Other securities		0	0
Net loans and direct financing leases		49	0
Financial Liabilities:
Deposits		74,423	73,975
Short-term borrowings		0	0
Long-term borrowings		8,986	8,944
Estimate of Fair Value Measurement [Member] \| Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		3,277	3,191
Held-to-maturity securities		0	0
Loans held for sale		68	78
Other securities		0	0
Net loans and direct financing leases		71,869	69,146
Financial Liabilities:
Deposits		7,208	3,035
Short-term borrowings		1,346	5,056
Long-term borrowings		537	458
Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account securities		83	86
Available-for-sale securities		13,727	14,869
Derivatives		180	132
Financial Liabilities:
Derivatives		220	86
Fair Value, Measurements, Recurring [Member] \| Level 1
Financial Assets:
Trading account securities		77	83
Available-for-sale securities		5	5
Fair Value, Measurements, Recurring [Member] \| Level 2
Financial Assets:
Trading account securities		6	3
Available-for-sale securities		10,445	11,673
Fair Value, Measurements, Recurring [Member] \| Level 3
Financial Assets:
Trading account securities		0	0
Available-for-sale securities		3,277	3,191
Other securities \| Fair Value, Measurements, Recurring [Member]
Financial Assets:
Trading account securities		78	86
Available-for-sale securities		4	2
Other securities \| Fair Value, Measurements, Recurring [Member] \| Level 1
Financial Assets:
Trading account securities		77	83
Available-for-sale securities		0	0
Other securities \| Fair Value, Measurements, Recurring [Member] \| Level 2
Financial Assets:
Trading account securities		1	3
Available-for-sale securities		4	2
Other securities \| 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		1,342	1,567
Held-to-maturity securities		8,465	9,091
Other Securities		543	581
Net loans and direct financing leases			69,333
Financial Liabilities:
Deposits		81,689	77,041
Short-term borrowings		1,348	5,056
Long-term borrowings		9,385	9,206
Fair Value Fair Value Option [Member] \| Reported Value Measurement [Member]
Financial Assets:
Trading account securities		83	86
Available-for-sale securities		13,727	14,869
Other Securities		22	19
Loans held for sale		727	413
Net loans and direct financing leases			93
Derivatives		180	132
Financial Liabilities:
Derivatives		220	86
LowerOfCostOrMarket [Member] \| Reported Value Measurement [Member]
Financial Assets:
Loans held for sale		$ 65	$ 75

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

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)group	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Derivative [Line Items]
Fair value hedging adjustments			$ (135)
Increase (decrease) to net interest income due to derivative adjustment	$ (11)	$ 3	(25)	$ 20
Derivative Liability	220		220		$ 86
Purchase of interest rate caps and derivative financial instruments, notional value	5,727		5,727		8,375
Credit risks from interest rate swaps used for trading purposes	$ 115		$ 115		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 September 30, 2018 and December 31, 2017 . September 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 1.5 $ — 2.20 % 2.16 % Liability conversion swaps Receive fixed—generic 5,715 2.5 (50 ) 2.08 2.26 Total swap portfolio at September 30, 2018 $ 5,727 2.5 $ (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	$ 17		$ 17		30
Investment securities and cash collateral pledged by Huntington	72		72
Investment securities and cash collateral pledged to Huntington	246		$ 246
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]			4,000,000
Derivative used in trading activity
Derivative [Line Items]
Net derivative asset (liability)	100		$ 100		88
Derivative financial instruments used by Huntington on behalf of customers including offsetting derivatives, notional value	25,000		25,000		22,000
Fair Value Hedging
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	5,715		5,715		8,375
Cash Flow Hedging
Derivative [Line Items]
Purchase of interest rate caps and derivative financial instruments, notional value	$ 12		$ 12		$ 0

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS - Hedging Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative, Notional Amount	$ 5,727	$ 8,375
Asset derivatives included in accrued income and other assets
Total contracts	498	322
Liability derivatives included in accrued expenses and other liabilities
Total contracts	441	331
Accrued income and other assets
Asset derivatives included in accrued income and other assets
Interest rate contracts designated as hedging instruments	15	22
Interest rate contracts not designated as hedging instruments	294	187
Foreign exchange contracts not designated as hedging instruments	28	18
Commodities contracts not designated as hedging instruments	157	92
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	4	3
Total contracts	498	322
Accrued expenses and other liabilities
Liability derivatives included in accrued expenses and other liabilities
Interest rate contracts designated as hedging instruments	65	121
Interest rate contracts not designated as hedging instruments	198	100
Foreign exchange contracts not designated as hedging instruments	22	18
Commodities contracts not designated as hedging instruments	152	87
Derivative Instruments Not Designated as Hedging Instruments, Liability, at Fair Value	4	5
Total contracts	$ 441	$ 331

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Management (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 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	$ 5,727	$ 8,375
Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	5,715	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	5,340	7,425
Other long-term debt \| Fair Value Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	5,340	7,425
Other long-term debt \| Cash Flow Hedging
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 0	$ 0
Asset conversion swaps Receive Fixed Generic
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
Credit Derivatives [Line Items]
Average maturity of interest rate derivative in years	2 years 2 months 12 days	2 years 6 months

DERIVATIVE FINANCIAL INSTRUME_6

DERIVATIVE FINANCIAL INSTRUMENTS - Asset and Liability Managemen Add Info (Details Add Info) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative, Notional Amount	$ 5,727	$ 8,375
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 5,727	8,375
Average Maturity (years)	2 years 6 months
Fair Value	$ (50)	$ (99)
Asset conversion swaps - Receive Fixed - Generic
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 12
Average Maturity (years)	1 year 8 months 12 days	0 years
Fair Value	$ 0
Weighted-Average Rate Receive	2.20%
Weighted-Average Rate Pay	2.16%
Liability conversion swaps - Receive Fixed - Generic
Additional information about the interest rate swaps used in companies Asset and Liability Management
Notional Value	$ 5,715	$ 8,375
Average Maturity (years)	2 years 2 months 12 days	2 years 6 months
Fair Value	$ (50)	$ (99)
Weighted-Average Rate Receive	2.08%	1.56%
Weighted-Average Rate Pay	2.26%	1.44%

DERIVATIVE FINANCIAL INSTRUME_7

DERIVATIVE FINANCIAL INSTRUMENTS - Gain (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 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 nine-month periods ended September 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 September 30, 2018 Nine Months Ended September 30, 2018 Interest rate contracts: Customer Capital markets fees $ 11 $ 30 Mortgage Banking Mortgage banking income 5 (3 ) Foreign exchange contracts Capital markets fees 6 18 Commodities contracts Capital markets fees 1 3 Equity contracts Other noninterest expense — 3 Total $ 23 $ 51
Gains and (losses) recognized in other comprehensive income (loss) (OCI) for derivatives designated as effective cash flow hedges
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 6		$ 18
Gain (Loss) on Commodity Contract Derivative Instruments Not Designated as Hedging Instruments	1		3
Gain (Loss) on Equity Contract Derivative Instruments Not Designated as Hedging Instruments	0		3
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	23		51
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	(2)	$ (2)	22	$ (5)
Hedged Subordinated notes \| Interest expense subordinated notes and other long term debt
Increase or (decrease) to interest expense for derivatives designated as fair value hedges
Increase or (decrease) to interest expense for derivatives designated as fair value hedges	2	4	(22)	7
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	(9)	(6)	33	(1)
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	10	$ 7	(27)	$ (1)
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	11		30
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ 5		$ (3)
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 INSTRUME_8

DERIVATIVE FINANCIAL INSTRUMENTS - Fair Value Hedges (Details) $ in Millions	Sep. 30, 2018USD ($)
Derivative Instruments, Gain (Loss) [Line Items]
Fair Value Hedge Liabilities	$ 5,637
Hedged Liability, Fair Value Hedge, Cumulative Increase (Decrease)	$ (67)

DERIVATIVE FINANCIAL INSTRUME_9

DERIVATIVE FINANCIAL INSTRUMENTS - Mortgage Banking Activities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative assets:
Total derivative assets	$ 498	$ 322
Derivative liabilities:
Total derivative liabilities	(441)	(331)
Derivative used in Mortgage Banking Activities
Derivatives, Fair Value [Line Items]
Derivative, Fair Value, Net	$ 8	$ 7

DERIVATIVE FINANCIAL INSTRUM_10

DERIVATIVE FINANCIAL INSTRUMENTS - MSR Hedging Activities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Notional Amount	$ 5,727	$ 8,375

DERIVATIVE FINANCIAL INSTRUM_11

DERIVATIVE FINANCIAL INSTRUMENTS - Offsetting Assets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized assets	$ 498	$ 322
Gross amounts offset in the condensed consolidated balance sheets	318	190
Net amounts of assets presented in the condensed consolidated balance sheets	180	132
Gross amounts not offset in the condensed consolidated balance sheets, Financial instruments	(2)	(11)
Gross amounts not offset in the condensed consolidated balance sheets, cash collateral received	(59)	(18)
Net amount	$ 119	$ 103

DERIVATIVE FINANCIAL INSTRUM_12

DERIVATIVE FINANCIAL INSTRUMENTS - Offsetting Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized liabilities	$ 441	$ 331
Gross amounts offset in the condensed consolidated balance sheets	(221)	(245)
Derivative liabilities	220	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	(15)	(21)
Net amount	$ 205	$ 65

VIEs - Narrative (Details)

VIEs - Narrative (Details)	3 Months Ended
VIEs - Narrative (Details)	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Maximum year to defer payment of interest on Debenture	5 years

VIEs - Unconsolidated VIEs (Det

VIEs - Unconsolidated VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
2016-1 Automobile Trust
Variable Interest Entity [Line Items]
Total Assets	$ 3	$ 7
Total Liabilities	1	0
Maximum Exposure to Loss	3	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	683	636
Total Liabilities	345	335
Maximum Exposure to Loss	683	636
Other Investments
Variable Interest Entity [Line Items]
Total Assets	125	117
Total Liabilities	54	53
Maximum Exposure to Loss	125	117
Total
Variable Interest Entity [Line Items]
Total Assets	825	775
Total Liabilities	652	640
Maximum Exposure to Loss	$ 811	$ 761

VIEs - Trust preferred Securiti

VIEs - Trust preferred Securities (Details) $ in Millions	3 Months Ended
VIEs - Trust preferred Securities (Details) $ in Millions	Sep. 30, 2018USD ($)
Summary of Outstanding Trust Preferred Securities
Principal amount of subordinated note/ debenture issued to trust	$ 252
Investment in unconsolidated subsidiary	$ 14
Huntington Capital I
Summary of Outstanding Trust Preferred Securities
Interest rate on Trust Preferred Securities	3.10%
Principal amount of subordinated note/ debenture issued to trust	$ 70
Investment in unconsolidated subsidiary	$ 6
Huntington Capital I \| London Interbank Offered Rate (LIBOR)
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	3.02%
Principal amount of subordinated note/ debenture issued to trust	$ 32
Investment in unconsolidated subsidiary	$ 3
Huntington Capital II \| London Interbank Offered Rate (LIBOR)
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	3.80%
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)
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	3.80%
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	3.73%
Principal amount of subordinated note/ debenture issued to trust	$ 4
Investment in unconsolidated subsidiary	$ 1
Camco Financial Trust \| London Interbank Offered Rate (LIBOR)
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		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Low Income Housing Tax Credit Partnerships
Variable Interest Entity [Line Items]
Affordable housing tax credit investments	$ 1,102		$ 1,102		$ 996
Less: amortization	(419)		(419)		(360)
Net affordable housing tax credit investments	683		683		636
Unfunded commitments	345		345		$ 335
Tax credits and other tax benefits recognized	24	$ 22	70	$ 68
Proportional Amortization Method
Variable Interest Entity [Line Items]
Tax credit amortization expense included in provision for income taxes	$ 19	$ 17	$ 59	$ 51

COMMITMENTS AND CONTINGENT LI_3

COMMITMENTS AND CONTINGENT LIABILITIES - Commitments to Extend Credit (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Commercial
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	$ 16,594	$ 16,219
Consumer
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	14,798	13,384
Commercial real estate
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	1,182	1,366
Standby letters of credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	623	510
Commercial \| Commercial letters-of-credit
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Contract amount represents credit risk	$ 33	$ 21

COMMITMENTS AND CONTINGENT LI_4

COMMITMENTS AND CONTINGENT LIABILITIES - Narrative (Details) - USD ($)	3 Months Ended
	Sep. 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	$ 10,000,000	$ 10,000,000
Outstanding standby letters of credit	623,000,000	510,000,000
Commitments to Sell Loans
Loss Contingencies [Line Items]
Commitments to sell residential real estate loans	1,075,000,000	$ 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		9 Months Ended
SEGMENT REPORTING (Details) $ in Millions	Sep. 30, 2018USD ($)reporting_unitsegments	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments \| segments	4
Maximum business banking customer's revenue	$ 20
Net interest income	802	$ 758	$ 2,356	$ 2,233
Provision (reduction in allowance) for credit losses	(53)	(43)	(175)	(136)
Noninterest income	342	330	992	967
Noninterest expense	651	680	1,936	2,082
Provision (benefit) for income taxes	62	90	178	228
Net income	378	275	1,059	754
Assets	105,652		105,652		$ 104,185
Deposits	81,689		81,689		77,041
Operating Segments \| Consumer & Business Banking
Segment Reporting Information [Line Items]
Net interest income	431	391	1,239	1,151
Provision (reduction in allowance) for credit losses	(42)	(24)	(101)	(75)
Noninterest income	192	189	553	544
Noninterest expense	425	416	1,266	1,242
Provision (benefit) for income taxes	33	49	89	132
Net income	123	91	336	246
Assets	27,362		27,362		26,220
Deposits	$ 49,434		49,434		45,643
Operating Segments \| Commercial Banking
Segment Reporting Information [Line Items]
Number of reporting units \| reporting_unit	6
Net interest income	$ 239	224	688	675
Provision (reduction in allowance) for credit losses	1	0	(38)	(15)
Noninterest income	79	67	228	201
Noninterest expense	124	117	373	353
Provision (benefit) for income taxes	41	61	106	178
Net income	154	113	399	330
Assets	33,759		33,759		32,118
Deposits	22,288		22,288		21,235
Operating Segments \| Vehicle Finance [Member]
Segment Reporting Information [Line Items]
Net interest income	101	108	300	318
Provision (reduction in allowance) for credit losses	(12)	(20)	(36)	(45)
Noninterest income	2	3	8	11
Noninterest expense	37	39	110	113
Provision (benefit) for income taxes	11	18	34	60
Net income	43	34	128	111
Assets	18,895		18,895		17,865
Deposits	348		348		358
Operating Segments \| RBPCG
Segment Reporting Information [Line Items]
Net interest income	48	43	139	126
Provision (reduction in allowance) for credit losses	0	0	0	(1)
Noninterest income	47	46	145	141
Noninterest expense	61	58	184	182
Provision (benefit) for income taxes	7	11	21	29
Net income	27	20	79	55
Assets	6,374		6,374		5,821
Deposits	5,783		5,783		6,057
Treasury / Other
Segment Reporting Information [Line Items]
Net interest income	(17)	(8)	(10)	(37)
Provision (reduction in allowance) for credit losses	0	1	0	0
Noninterest income	22	25	58	70
Noninterest expense	4	50	3	192
Provision (benefit) for income taxes	(30)	(49)	(72)	(171)
Net income	31	$ 17	117	$ 12
Assets	19,262		19,262		22,161
Deposits	$ 3,836		$ 3,836		$ 3,748