F.N.B. (FNB) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-31940
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	25-1255406
Entity Address, Address Line One	One North Shore Center,
Entity Address, Address Line Two	12 Federal Street,
Entity Address, City or Town	Pittsburgh,
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	15212
City Area Code	800
Local Phone Number	555-5455
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		319,385,342
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Registrant Name	FNB CORP/PA/
Entity Central Index Key	0000037808
Current Fiscal Year End Date	--12-31
New York Stock Exchange | Common Stock, par value $0.01 per share
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	FNB
Security Exchange Name	NYSE
New York Stock Exchange | Depositary Shares each representing 1/40th interest in a share of Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series E
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shares each representing 1/40th interest in a share of Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series E
Trading Symbol	FNBPrE
Security Exchange Name	NYSE

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Assets
Cash and due from banks		$ 339	$ 369
Interest-bearing deposits with banks		2,329	1,014
Cash and Cash Equivalents		2,668	1,383
Debt securities available for sale (amortized cost of $3,110 and $3,380; allowance for credit losses of $0 and $0)		3,166	3,463
Debt securities held to maturity (fair value of $3,114 and $2,973; allowance for credit losses of $0 and $0 )		3,043	2,868
Loans held for sale (includes $165 and $144 measured at fair value)	[1]	185	154
Loans and leases, net of unearned income of $93 and $77		25,532	25,459
Allowance for credit losses		(362)	(363)
Net Loans and Leases		25,170	25,096
Premises and equipment, net		330	332
Goodwill		2,262	2,262
Core deposit and other intangible assets, net		51	54
Bank owned life insurance		549	549
Other assets		1,051	1,193
Total Assets		38,475	37,354
Liabilities
Non-interest-bearing demand		9,935	9,042
Interest-bearing demand		13,684	13,157
Savings		3,351	3,261
Certificates and other time deposits		3,384	3,662
Total Deposits		30,354	29,122
Short-term borrowings		1,687	1,804
Long-term borrowings		1,091	1,095
Other liabilities		369	374
Total Liabilities		33,501	32,395
Stockholders’ Equity
Preferred stock - $0.01 par value; liquidation preference of $1,000 per share Authorized - 20,000,000 shares Issued - 110,877 shares		107	107
Common stock - $0.01 par value Authorized - 500,000,000 shares Issued - 328,213,157 and 328,057,368 shares		3	3
Additional paid-in capital		4,099	4,087
Retained earnings		921	869
Accumulated other comprehensive loss		(51)	(39)
Treasury stock – 9,516,731 and 6,427,839 shares at cost		(105)	(68)
Total Stockholders’ Equity		4,974	4,959
Total Liabilities and Stockholders’ Equity		$ 38,475	$ 37,354
[1]	Amount represents loans for which we have elected the fair value option. See Note 18.

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)		Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Debt securities available for sale, amortized cost		$ 3,110,000,000	$ 3,380,000,000
Debt securities available for sale, allowance for credit losses		0	0
Debt securities held-to-maturity, fair value		3,114,000,000	2,973,000,000
Debt securities held to maturity, allowance for credit losses		40,000	40,000
Loans held for sale, fair value	[1]	165,000,000	144,000,000
Unearned income on loans		$ 93,000,000	$ 77,000,000
Preferred stock, par value (in dollars per share)		$ 0.01	$ 0.01
Preferred stock, liquidation preference per share (in dollars per share)		$ 1,000	$ 1,000
Preferred stock, shares authorized		20,000,000	20,000,000
Preferred stock, shares issued		110,877	110,877
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Common stock, shares authorized		500,000,000	500,000,000
Common stock, shares issued		328,213,157	328,057,368
Treasury stock, shares		9,516,731	6,427,839
[1]	Amount represents loans for which we have elected the fair value option. See Note 18.

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest Income
Loans and leases, including fees	$ 221	$ 266
Securities:
Taxable	22	31
Tax-exempt	8	8
Other	0	1
Total Interest Income	251	306
Interest Expense
Deposits	15	49
Short-term borrowings	7	14
Long-term borrowings	6	11
Total Interest Expense	28	74
Net Interest Income	223	232
Provision for credit losses	6	48
Net Interest Income After Provision for Credit Losses	217	184
Non-Interest Income
Service charges	28	30
Trust services	9	8
Insurance commissions and fees	7	7
Securities commissions and fees	6	5
Capital markets income	8	11
Mortgage banking operations	16	(1)
Dividends on non-marketable equity securities	2	5
Bank owned life insurance	3	3
Other	4	1
Total Non-Interest Income	83	69
Non-Interest Expense
Salaries and employee benefits	107	104
Net occupancy	16	21
Equipment	17	16
Amortization of intangibles	3	3
Outside services	17	17
FDIC insurance	5	6
Bank shares and franchise taxes	4	4
Other	16	24
Total Non-Interest Expense	185	195
Income Before Income Taxes	115	58
Income taxes	22	11
Net Income	93	47
Preferred stock dividends	2	2
Net Income Available to Common Stockholders	$ 91	$ 45
Earnings per Common Share
Basic (in USD per share)	$ 0.28	$ 0.14
Diluted (in USD per share)	$ 0.28	$ 0.14

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 93	$ 47
Securities available for sale:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $(6) and $15	(21)	53
Derivative instruments:
Unrealized gains (losses) arising during the period, net of tax expense (benefit) of $1 and $(10)	4	(35)
Reclassification adjustment for gains (losses) included in net income, net of tax expense (benefit) of $1 and $0	4	1
Pension and postretirement benefit obligations:
Unrealized gains arising during the period, net of tax expense of $0 and $0	1	1
Other Comprehensive Income (Loss)	(12)	20
Comprehensive Income	$ 81	$ 67

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Unrealized gains (losses) arising during the period, tax expense (benefit)	$ (6)	$ 15
Unrealized gains (losses) arising during the period, tax expense (benefit)	1	(10)
Reclassification adjustment for (gains) losses included in net income, tax of expense (benefit)	1	0
Unrealized gains arising during the period, tax expense	$ 0	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Adoption of new accounting standard [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]Adoption of new accounting standard [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at beginning of period at Dec. 31, 2019	$ 4,883		$ 107	$ 3	$ 4,067	$ 798		$ (65)	$ (27)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	67					47		20
Dividends declared:
Preferred stock	(2)					(2)
Common stock	(39)					(39)
Repurchase of common stock	(25)								(25)
Restricted stock compensation	8				8
Balance at end of period at Mar. 31, 2020	4,842	$ (50)	107	3	4,075	754	$ (50)	(45)	(52)
Balance at beginning of period at Dec. 31, 2020	4,959		107	3	4,087	869		(39)	(68)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	81					93		(12)
Dividends declared:
Preferred stock	(2)					(2)
Common stock	(39)					(39)
Issuance of common stock	0				1				(1)
Repurchase of common stock	(36)								(36)
Restricted stock compensation	11				11
Balance at end of period at Mar. 31, 2021	$ 4,974		$ 107	$ 3	$ 4,099	$ 921		$ (51)	$ (105)

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Preferred stock dividends per share (in USD per share)	$ 18.13	$ 18.13
Common stock dividends per share (in USD per share)	$ 0.12	$ 0.12

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net income	$ 93	$ 47
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation, amortization and accretion	1	4
Provision for credit losses	6	48
Deferred tax expense (benefit)	(1)	2
Loans originated for sale	(566)	(301)
Loans sold	550	275
Net gain on sale of loans	(16)	(5)
Net change in:
Interest receivable	1	21
Interest payable	(4)	(2)
Bank owned life insurance, excluding purchases	0	(2)
Other, net	151	(292)
Net cash flows (used in) provided by operating activities	215	(205)
Investing Activities
Net change in loans and leases, excluding sales and transfers	(59)	(500)
Debt securities available for sale:
Purchases	(567)	(54)
Maturities/payments	835	215
Debt securities held to maturity:
Purchases	(365)	(59)
Maturities/payments	188	154
Increase in premises and equipment	(8)	(8)
Net cash flows provided by (used in) investing activities	24	(252)
Financing Activities
Demand (non-interest bearing and interest bearing) and savings accounts	1,510	126
Time deposits	(278)	(166)
Short-term borrowings	(117)	228
Proceeds from issuance of long-term borrowings	4	307
Repayment of long-term borrowings	(7)	(15)
Repurchases of common stock	(36)	(25)
Cash dividends paid:
Preferred stock	(2)	(2)
Common stock	(39)	(39)
Other, net	11	8
Net cash flows provided by financing activities	1,046	422
Net Increase (Decrease) in Cash and Cash Equivalents	1,285	(35)
Cash and cash equivalents at beginning of period	1,383	599
Cash and Cash Equivalents at End of Period	$ 2,668	$ 564

NATURE OF OPERATIONS

NATURE OF OPERATIONS	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NATURE OF OPERATIONS	NATURE OF OPERATIONS F.N.B. Corporation, headquartered in Pittsburgh, Pennsylvania, is a diversified financial services company operating in seven states and the District of Columbia. Our market coverage spans several major metropolitan areas including: Pittsburgh, Pennsylvania; Baltimore, Maryland; Cleveland, Ohio; Washington, D.C.; and Charlotte, Raleigh, Durham and the Piedmont Triad (Winston-Salem, Greensboro and High Point) in North Carolina. As of March 31, 2021, we had 337 banking offices throughout Pennsylvania, Ohio, Maryland, West Virginia, North Carolina, South Carolina, Washington D.C. and Virginia.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation Our accompanying Consolidated Financial Statements and these Notes to Consolidated Financial Statements (unaudited) include subsidiaries in which we have a controlling financial interest. We own and operate FNBPA, First National Trust Company, First National Investment Services Company, LLC, F.N.B. Investment Advisors, Inc., First National Insurance Agency, LLC, Bank Capital Services, LLC and F.N.B. Capital Corporation, LLC, and include results for each of these entities in the accompanying Consolidated Financial Statements. Companies in which we hold a controlling financial interest, or are a VIE in which we have the power to direct the activities of an entity that most significantly impact the entity’s economic performance and have an obligation to absorb losses or the right to receive benefits which could potentially be significant to the VIE, are consolidated. For a voting interest entity, a controlling financial interest is generally where we hold more than 50% of the outstanding voting shares. VIEs in which we do not hold the power to direct the activities of the entity that most significantly impact the entity’s economic performance or an obligation to absorb losses or the right to receive benefits which could potentially be significant to the VIE are not consolidated. Investments in companies that are not consolidated are accounted for using the equity method when we have the ability to exert significant influence or the cost method when we do not have the ability to exert significant influence. Investments in private investment partnerships that are accounted for under the equity method or the cost method are included in other assets and our proportional interest in the equity investments’ earnings are included in other non-interest income. Investment interests accounted for under the cost and equity methods are periodically evaluated for impairment. The accompanying interim unaudited Consolidated Financial Statements include all adjustments that are necessary, in the opinion of management, to fairly reflect our financial position and results of operations in accordance with GAAP. All significant intercompany balances and transactions have been eliminated. Certain prior period amounts have been reclassified to conform to the current period presentation. Such reclassifications had no impact on our net income and stockholders’ equity. Events occurring subsequent to March 31, 2021 have been evaluated for potential recognition or disclosure in the Consolidated Financial Statements through the date of the filing of the Consolidated Financial Statements with the Securities and Exchange Commission. Certain information and Note disclosures normally included in Consolidated Financial Statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. The interim operating results are not necessarily indicative of operating results FNB expects for the full year. These interim unaudited Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and Notes thereto included in our 2020 Annual Report on Form 10-K filed with the SEC on February 25, 2021. Use of Estimates Our accounting and reporting policies conform with GAAP. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying Notes to Consolidated Financial Statements (unaudited). Actual results could materially differ from those estimates. Material estimates that are particularly susceptible to significant changes include the ACL, fair value of financial instruments, goodwill and other intangible assets, income taxes and deferred tax assets and litigation reserves, which are listed in the critical accounting estimates. For a detailed description of our significant accounting policies and critical accounting estimates, see Note 1, "Summary of Significant Accounting Policies" and the "Application of Critical Accounting Policies" section in the MD&A, both in our 2020 Annual Report on Form 10-K .

NEW ACCOUNTING STANDARDS

NEW ACCOUNTING STANDARDS	3 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
NEW ACCOUNTING STANDARDS	NEW ACCOUNTING STANDARDS The following table summarizes accounting pronouncements issued by the FASB that we recently adopted. TABLE 2.1 Standard Description Financial Statements Impact Reference Rate Reform ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ASU 2021-01, Reference Rate Reform (Topic 848): Scope These Updates provide temporary optional expedients and exceptions for applying GAAP to financial contracts, hedging relationships and other transactions affected by RRR if certain criteria are met. The following optional expedients, exceptions and elections are permitted for certain contracts that are modified because of RRR and meet certain scope guidance: • Contract modifications may be accounted for prospectively as a continuation of existing contracts rather than a new contract without remeasurement or reassessment of significant contract amendments • modifications of leases to be accounted for as a continuation of the existing contracts without reassessment of lease classification and discount rate or remeasurement of lease payments • to not reassess the original conclusion about whether a contract contains an embedded derivative that is clearly and closely related to the host contract • changes to critical terms of hedging relationships, on a hedge-by-hedge basis, without designation of the hedging relationship and various practical expedients and elections designed to allow hedge accounting to continue uninterrupted • modifications of certain derivatives modified to change the rate used for margining, discounting or contract price alignment. The Updates also allow an entity to make a one-time election to sell and/or transfer to HTM securities that are affected by RRR and were classified as HTM before January 1, 2020. RRR Updates are effective for all entities from the beginning of an interim period that includes or is subsequent to March 12, 2020 and terminates on December 31, 2022 on a full retrospective or prospective basis. Although we do not expect RRR to have a material accounting impact on our consolidated financial position or results of operations, the Updates will ease the administrative burden in accounting for the effects of RRR. We adopted these updates on October 1, 2020 by retrospective application. The adoption did not have a material impact on our consolidated financial position or results of operations. We will continue to assess the impact of adoption through the termination date of these Updates on December 31, 2022.

SECURITIES

SECURITIES	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
SECURITIES	SECURITIES The amortized cost and fair value of AFS debt securities are presented in the table below. There was no ACL in the AFS portfolio at March 31, 2021 and December 31, 2020. Accrued interest receivable on AFS debt securities totaled $5.9 million and $6.2 million at March 31, 2021 and December 31, 2020, respectively, and is excluded from the estimate of credit losses and assessed separately in other assets in the Consolidated Balance Sheets. Accordingly, we have excluded accrued interest receivable from both the fair value and the amortized cost basis of AFS debt securities. TABLE 3.1 (in millions) Amortized Gross Gross Fair Debt Securities AFS: March 31, 2021 U.S. Treasury $ 100 $ — $ — $ 100 U.S. government agencies 175 — — 175 U.S. government-sponsored entities 160 1 (1) 160 Residential mortgage-backed securities: Agency mortgage-backed securities 1,074 30 (1) 1,103 Agency collateralized mortgage obligations 1,242 26 (5) 1,263 Commercial mortgage-backed securities 328 9 (2) 335 States of the U.S. and political subdivisions (municipals) 29 — (1) 28 Other debt securities 2 — — 2 Total debt securities AFS $ 3,110 $ 66 $ (10) $ 3,166 (in millions) Amortized Gross Gross Fair Debt Securities AFS: December 31, 2020 U.S. Treasury $ 600 $ — $ — $ 600 U.S. government agencies 172 — — 172 U.S. government-sponsored entities 160 1 — 161 Residential mortgage-backed securities: Agency mortgage-backed securities 959 35 — 994 Agency collateralized mortgage obligations 1,094 31 (1) 1,124 Commercial mortgage-backed securities 361 17 — 378 States of the U.S. and political subdivisions (municipals) 32 — — 32 Other debt securities 2 — — 2 Total debt securities AFS $ 3,380 $ 84 $ (1) $ 3,463 The amortized cost and fair value of HTM debt securities are presented in the table below. The ACL for the HTM municipal bond portfolio was $0.04 million at both March 31, 2021 and December 31, 2020. Accrued interest receivable on HTM debt securities totaled $11.5 million and $12.5 million at March 31, 2021 and December 31, 2020, respectively, and is excluded from the estimate of credit losses and assessed separately in other assets in the Consolidated Balance Sheets. TABLE 3.2 (in millions) Amortized Gross Gross Fair Debt Securities HTM: March 31, 2021 U.S. Treasury $ 1 $ — $ — $ 1 U.S. government agencies 1 — — 1 U.S. government-sponsored entities 100 — — 100 Residential mortgage-backed securities: Agency mortgage-backed securities 889 22 (2) 909 Agency collateralized mortgage obligations 643 14 (2) 655 Commercial mortgage-backed securities 314 4 (3) 315 States of the U.S. and political subdivisions (municipals) 1,095 39 (1) 1,133 Total debt securities HTM $ 3,043 $ 79 $ (8) $ 3,114 (in millions) Amortized Gross Gross Fair Debt Securities HTM: December 31, 2020 U.S. Treasury $ 1 $ — $ — $ 1 U.S. government agencies 1 — — 1 U.S. government-sponsored entities 120 1 — 121 Residential mortgage-backed securities: Agency mortgage-backed securities 769 29 — 798 Agency collateralized mortgage obligations 562 17 — 579 Commercial mortgage-backed securities 307 10 — 317 States of the U.S. and political subdivisions (municipals) 1,108 48 — 1,156 Total debt securities HTM $ 2,868 $ 105 $ — $ 2,973 There were no significant gross gains or gross losses realized on securities during the three months ended March 31, 2021 or 2020. As of March 31, 2021, the amortized cost and fair value of debt securities, by contractual maturities, were as follows: TABLE 3.3 Available for Sale Held to Maturity (in millions) Amortized Fair Amortized Fair Due in one year or less $ 185 $ 186 $ 100 $ 101 Due after one year but within five years 70 69 21 21 Due after five years but within ten years 127 126 145 147 Due after ten years 84 84 931 966 466 465 1,197 1,235 Residential mortgage-backed securities: Agency mortgage-backed securities 1,074 1,103 889 909 Agency collateralized mortgage obligations 1,242 1,263 643 655 Commercial mortgage-backed securities 328 335 314 315 Total debt securities $ 3,110 $ 3,166 $ 3,043 $ 3,114 Actual maturities may differ from contractual terms because security issuers may have the right to call or prepay obligations with or without penalties. Periodic principal payments are received on residential mortgage-backed securities based on the payment patterns of the underlying collateral. Following is information relating to securities pledged: TABLE 3.4 (dollars in millions) March 31, December 31, Securities pledged (carrying value): To secure public deposits, trust deposits and for other purposes as required by law $ 5,429 $ 5,384 As collateral for short-term borrowings 434 402 Securities pledged as a percent of total securities 94.4 % 91.4 % At March 31, 2021, there were no holdings of securities of any one issuer, other than the U.S. government and its agencies, in any amount greater than 10% of stockholders’ equity. Following are summaries of the fair values of AFS debt securities in an unrealized loss position for which an ACL has not been recorded, segregated by security type and length of continuous loss position: TABLE 3.5 Less than 12 Months 12 Months or More Total (dollars in millions) # Fair Unrealized # Fair Unrealized # Fair Unrealized Debt Securities AFS March 31, 2021 U.S. government agencies 1 $ 1 $ — 16 $ 65 $ — 17 $ 66 $ — U.S. government-sponsored entities 2 74 (1) — — — 2 74 (1) Residential mortgage-backed securities: Agency mortgage-backed securities 2 103 (1) — — — 2 103 (1) Agency collateralized mortgage obligations 10 399 (5) — — — 10 399 (5) Commercial mortgage-backed securities 4 103 (2) — — — 4 103 (2) States of the U.S. and political subdivisions (municipals) 8 22 (1) — — — 8 22 (1) Other debt securities — — — 1 2 — 1 2 — Total 27 $ 702 $ (10) 17 $ 67 $ — 44 $ 769 $ (10) Less than 12 Months 12 Months or More Total (dollars in millions) # Fair Unrealized # Fair Unrealized # Fair Unrealized Debt Securities AFS December 31, 2020 U.S. government agencies 1 $ 13 $ — 16 $ 69 $ — 17 $ 82 $ — U.S. government-sponsored entities 1 25 — — — — 1 25 — Residential mortgage-backed securities: Agency collateralized mortgage obligations 5 130 (1) — — — 5 130 (1) Other debt securities — — — 1 2 — 1 2 — Total 7 $ 168 $ (1) 17 $ 71 $ — 24 $ 239 $ (1) We evaluated the AFS debt securities that were in an unrealized loss position at March 31, 2021. Based on the credit ratings and implied government guarantee for these securities, we concluded the loss position is temporary and caused by the movement of interest rates and does not reflect any expected credit losses. We do not intend to sell the AFS debt securities and it is not more likely than not that we will be required to sell the securities before the recovery of their amortized cost basis. Credit Quality Indicators We use credit ratings and the most recent financial information to help evaluate the credit quality of our credit-related AFS and HTM securities portfolios. Management reviews the credit profile of each issuer on a quarterly basis. Based on the nature of the issuers and current conditions, we have determined that securities backed by the UST, Fannie Mae, Freddie Mac, FHLB, Ginnie Mae, and the SBA have zero expected credit loss. Our municipal bond portfolio, with a carrying amount of $1.1 billion as of March 31, 2021 is highly rated with an average rating of AA and 99% of the portfolio having an A or better rating. All of the securities in the municipal portfolio are general obligation bonds. Geographically, municipal bonds support our primary footprint as 65% of the securities are from municipalities located in the primary states within which we conduct business. The average holding size of the securities in the municipal bond portfolio is $3.6 million. In addition to the strong stand-alone ratings, 62% of the municipal bonds have some formal credit enhancement (e.g., insurance) that strengthens the creditworthiness of the bond. The ACL on the HTM municipal bond portfolio is calculated on each bond using: • The bond’s underlying credit rating, time to maturity and exposure amount; • Credit enhancements that improve the bond’s credit rating (e.g., insurance); and • Moody’s U.S. Bond Defaults and Recoveries, 1970-2019 study. By using these components, we derive the expected credit loss on the HTM general obligation bond portfolio. We further refine the expected credit loss by factoring in economic forecast data using our Commercial and Industrial Non-Manufacturing loan portfolio forecast adjustment as derived through our assessment of the loan portfolio as a proxy for our municipal bond portfolio. For the year-to-date periods ending March 31, 2021 and 2020, we had no significant provision expense and no charge-offs or recoveries. The ACL on the HTM portfolio was $0.04 million as of both March 31, 2021 and December 31, 2020, respectively. No other securities portfolios had an ACL. At March 31, 2021 and December 31, 2020, there were no securities that were past due or on non-accrual.

LOANS AND LEASES

LOANS AND LEASES	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
LOANS AND LEASES	LOANS AND LEASES Accrued interest receivable on loans and leases, which totaled $63.5 million at March 31, 2021 and $62.9 million at December 31, 2020, is excluded from the estimate of credit losses and assessed separately in other assets in the Consolidated Balance Sheets for both periods and not included in the tables below. Upon adoption of CECL on January 1, 2020, PCD assets were adjusted to reflect the addition of a $50.3 million ACL and a remaining noncredit discount of $110.0 million included in the amortized cost. The remaining noncredit discount was $44.3 million and $50.9 million at March 31, 2021 and December 31, 2020, respectively. Loans and Leases by Portfolio Segment Following is a summary of total loans and leases, net of unearned income: TABLE 4.1 (in millions) March 31, 2021 December 31, 2020 Commercial real estate $ 9,799 $ 9,731 Commercial and industrial 7,401 7,214 Commercial leases 471 485 Other 25 40 Total commercial loans and leases 17,696 17,470 Direct installment 2,025 2,020 Residential mortgages 3,329 3,433 Indirect installment 1,201 1,218 Consumer lines of credit 1,281 1,318 Total consumer loans 7,836 7,989 Total loans and leases, net of unearned income $ 25,532 $ 25,459 The loans and leases portfolio categories are comprised of the following types of loans, where in each case the LGD is dependent on the nature and value of the respective collateral: • Commercial real estate includes both owner-occupied and non-owner-occupied loans secured by commercial properties where operational cash flows on owner-occupied properties or rents received by our borrowers from their tenant(s) on both a property and global basis are the primary default risk drivers, including rents paid by stand-alone business customers for owner-occupied properties; • Commercial and industrial includes loans to businesses that are not secured by real estate where the borrower's leverage and cash flows from operations are the primary default risk drivers. PPP loans are included in the commercial and industrial category and comprise $2.5 billion and $2.2 billion of this category's outstanding balance at March 31, 2021 and December 31, 2020, respectively. The PPP loans are 100% guaranteed by the SBA, which provides a reduced risk of loss to us on these loans; • Commercial leases consist of leases for new or used equipment where the borrower's cash flow from operations is the primary default risk driver; • Other is comprised primarily of credit cards and mezzanine loans where the borrower's cash flow from operations is the primary default risk driver; • Direct installment is comprised of fixed-rate, closed-end consumer loans for personal, family or household use, such as home equity loans and automobile loans where the primary default risk driver is the borrower's employment status and income; • Residential mortgages consist of conventional and jumbo mortgage loans for 1-4 family properties where the primary default risk driver is the borrower's employment status and income; • Indirect installment is comprised of loans originated by approved third parties and underwritten by us, primarily automobile loans where the primary default risk driver is the borrower's employment status and income; and • Consumer lines of credit include home equity lines of credit and consumer lines of credit that are either unsecured or secured by collateral other than home equity where the primary default risk driver is the borrower's employment status and income. The loans and leases portfolio consists principally of loans to individuals and small- and medium-sized businesses within our primary market in seven states and the District of Columbia. Our primary market coverage spans several major metropolitan areas including: Pittsburgh, Pennsylvania; Baltimore, Maryland; Cleveland, Ohio; Washington, D.C.; and Charlotte, Raleigh, Durham and the Piedmont Triad (Winston-Salem, Greensboro and High Point) in North Carolina. The following table shows occupancy information relating to commercial real estate loans: TABLE 4.2 (dollars in millions) March 31, December 31, Commercial real estate: Percent owner-occupied 28.1 % 28.1 % Percent non-owner-occupied 71.9 71.9 Credit Quality Management monitors the credit quality of our loan portfolio using several performance measures based on payment activity and borrower performance. We use an internal risk rating assigned to a commercial loan or lease at origination, summarized below. TABLE 4.3 Rating Category Definition Pass in general, the condition of the borrower and the performance of the loan is satisfactory or better Special Mention in general, the condition of the borrower has deteriorated, requiring an increased level of monitoring Substandard in general, the condition of the borrower has significantly deteriorated and the performance of the loan could further deteriorate if deficiencies are not corrected Doubtful in general, the condition of the borrower has significantly deteriorated and the collection in full of both principal and interest is highly questionable or improbable The use of these internally assigned credit quality categories within the commercial loan and lease portfolio permits management’s use of transition matrices to establish a basis which is then impacted by quantitative inputs from our econometric model forecasts over the R&S period. Our internal credit risk grading system is based on past experiences with similarly graded loans and leases and conforms to regulatory categories. In general, loan and lease risk ratings within each category are reviewed on an ongoing basis according to our policy for each class of loans and leases. Each quarter, management analyzes the resulting ratings, as well as other external statistics and factors such as delinquency, to track the migration performance of the commercial loan and lease portfolio. Loans and leases within the Pass credit category or that migrate toward the Pass credit category generally have a lower risk of loss compared to loans and leases that migrate toward the Substandard or Doubtful credit categories. Accordingly, management applies higher risk factors to Substandard and Doubtful credit categories. The following tables summarize the designated loan rating category by loan class including term loans on an amortized cost basis by origination year: TABLE 4.4 March 31, 2021 2021 2020 2019 2018 2017 Prior Revolving Loans Amortized Cost Basis Total (in millions) COMMERCIAL Commercial Real Estate: Risk Rating: Pass $ 323 $ 1,876 $ 1,874 $ 1,080 $ 881 $ 2,680 $ 145 $ 8,859 Special Mention 5 12 32 93 151 191 5 489 Substandard — 8 33 41 73 291 5 451 Total commercial real estate 328 1,896 1,939 1,214 1,105 3,162 155 9,799 Commercial and Industrial: Risk Rating: Pass 1,116 2,642 921 561 280 354 1,030 6,904 Special Mention — 32 20 9 28 67 53 209 Substandard 2 8 28 57 45 44 104 288 Total commercial and industrial 1,118 2,682 969 627 353 465 1,187 7,401 Commercial Leases: Risk Rating: Pass 34 158 124 73 52 6 — 447 Special Mention — — 1 3 3 3 — 10 Substandard — 8 3 2 1 — — 14 Total commercial leases 34 166 128 78 56 9 — 471 Other Commercial: Risk Rating: Pass 6 — — — — 4 15 25 Substandard — — — — — — — — Total other commercial 6 — — — — 4 15 25 Total commercial 1,486 4,744 3,036 1,919 1,514 3,640 1,357 17,696 CONSUMER Direct Installment: Current 154 676 306 182 130 560 — 2,008 Past due — — 1 1 1 14 — 17 Total direct installment 154 676 307 183 131 574 — 2,025 Residential Mortgages: Current 248 1,033 586 239 327 856 1 3,290 Past due — 1 2 3 4 29 — 39 Total residential mortgages 248 1,034 588 242 331 885 1 3,329 Indirect Installment: Current 122 353 233 289 123 75 — 1,195 Past due — 1 2 1 1 1 — 6 Total indirect installment 122 354 235 290 124 76 — 1,201 Consumer Lines of Credit: Current 1 4 5 8 3 132 1,114 1,267 Past due — — — — — 13 1 14 Total consumer lines of credit 1 4 5 8 3 145 1,115 1,281 Total consumer 525 2,068 1,135 723 589 1,680 1,116 7,836 Total loans and leases $ 2,011 $ 6,812 $ 4,171 $ 2,642 $ 2,103 $ 5,320 $ 2,473 $ 25,532 December 31, 2020 2020 2019 2018 2017 2016 Prior Revolving Loans Amortized Cost Basis Total (in millions) COMMERCIAL Commercial Real Estate: Risk Rating: Pass $ 1,879 $ 1,854 $ 1,135 $ 927 $ 888 $ 1,911 $ 163 $ 8,757 Special Mention 9 30 80 158 70 163 4 514 Substandard 4 32 29 81 116 192 6 460 Total commercial real estate 1,892 1,916 1,244 1,166 1,074 2,266 173 9,731 Commercial and Industrial: Risk Rating: Pass 3,286 1,007 590 304 120 311 1,095 6,713 Special Mention 30 23 13 28 10 35 79 218 Substandard 8 26 65 44 6 37 97 283 Total commercial and industrial 3,324 1,056 668 376 136 383 1,271 7,214 Commercial Leases: Risk Rating: Pass 178 134 83 56 5 3 — 459 Special Mention 1 1 4 4 1 2 — 13 Substandard 7 2 2 1 1 — — 13 Total commercial leases 186 137 89 61 7 5 — 485 Other Commercial: Risk Rating: Pass — — — — — 4 35 39 Substandard — — — — — 1 — 1 Total other commercial — — — — — 5 35 40 Total commercial 5,402 3,109 2,001 1,603 1,217 2,659 1,479 17,470 CONSUMER Direct Installment: Current 706 337 200 143 171 442 1 2,000 Past due — 1 2 1 2 14 — 20 Total direct installment 706 338 202 144 173 456 1 2,020 Residential Mortgages: Current 1,079 707 283 378 330 603 1 3,381 Past due 1 5 7 4 6 29 — 52 Total residential mortgages 1,080 712 290 382 336 632 1 3,433 Indirect Installment: Current 372 260 332 147 67 27 — 1,205 Past due 1 3 4 2 2 1 — 13 Total indirect installment 373 263 336 149 69 28 — 1,218 Consumer Lines of Credit: Current 4 7 8 3 5 127 1,146 1,300 Past due — — — — — 15 3 18 Total consumer lines of credit 4 7 8 3 5 142 1,149 1,318 Total consumer 2,163 1,320 836 678 583 1,258 1,151 7,989 Total loans and leases $ 7,565 $ 4,429 $ 2,837 $ 2,281 $ 1,800 $ 3,917 $ 2,630 $ 25,459 We use delinquency transition matrices within the consumer and other loan classes to establish the basis for the R&S forecast portion of the credit risk. Each month, management analyzes payment and volume activity, Fair Isaac Corporation (FICO) scores and Debt-to-Income (DTI) scores and other external factors such as unemployment, to determine how consumer loans are performing. Non-Performing and Past Due The following tables provide an analysis of the aging of loans by class. TABLE 4.5 (in millions) 30-89 Days > 90 Days Past Due and Still Accruing Non- Total Current Total Non-accrual with No ACL March 31, 2021 Commercial real estate $ 8 $ — $ 78 $ 86 $ 9,713 $ 9,799 $ 30 Commercial and industrial 2 — 36 38 7,363 7,401 15 Commercial leases 3 — 2 5 466 471 — Other — — — — 25 25 — Total commercial loans and leases 13 — 116 129 17,567 17,696 45 Direct installment 5 1 11 17 2,008 2,025 — Residential mortgages 12 6 21 39 3,290 3,329 — Indirect installment 4 — 2 6 1,195 1,201 — Consumer lines of credit 4 3 7 14 1,267 1,281 — Total consumer loans 25 10 41 76 7,760 7,836 — Total loans and leases $ 38 $ 10 $ 157 $ 205 $ 25,327 $ 25,532 $ 45 (in millions) 30-89 Days > 90 Days Past Due and Still Accruing Non- Total Current Total Non-accrual with No ACL December 31, 2020 Commercial real estate $ 13 $ — $ 85 $ 98 $ 9,633 $ 9,731 $ 36 Commercial and industrial 8 — 44 52 7,162 7,214 16 Commercial leases 2 — 2 4 481 485 — Other — — 1 1 39 40 — Total commercial loans and leases 23 — 132 155 17,315 17,470 52 Direct installment 7 2 11 20 2,000 2,020 — Residential mortgages 23 11 18 52 3,381 3,433 — Indirect installment 10 1 2 13 1,205 1,218 — Consumer lines of credit 9 2 7 18 1,300 1,318 — Total consumer loans 49 16 38 103 7,886 7,989 — Total loans and leases $ 72 $ 16 $ 170 $ 258 $ 25,201 $ 25,459 $ 52 Following is a summary of non-performing assets: TABLE 4.6 (dollars in millions) March 31, December 31, Non-accrual loans $ 157 $ 170 Total non-performing loans 157 170 Other real estate owned 9 10 Total non-performing assets $ 166 $ 180 Asset quality ratios: Non-performing loans / total loans and leases 0.62 % 0.67 % Non-performing assets + 90 days past due + OREO / total loans and leases + OREO 0.68 0.77 The carrying value of residential-secured consumer OREO held as a result of obtaining physical possession upon completion of a foreclosure or through completion of a deed in lieu of foreclosure amounted to $1.6 million at March 31, 2021 and $2.5 million at December 31, 2020. The recorded investment of residential-secured consumer OREO for which formal foreclosure proceedings are in process at March 31, 2021 and December 31, 2020 totaled $7.6 million and $8.2 million, respectively. During 2020 and 2021, we extended the residential mortgage foreclosure moratorium beyond the requirements for government-backed loans, under the CARES Act, to all residential mortgage loan customers. Approximately $85 million of commercial loans are collateral dependent at March 31, 2021. Repayment is expected to be substantially through the operation or sale of the collateral on the loan. These loans are primarily secured by business assets or commercial real estate. Troubled Debt Restructurings TDRs are loans whose contractual terms have been modified in a manner that grants a concession to a borrower experiencing financial difficulties. TDRs typically result from loss mitigation activities and could include the extension of a maturity date, interest rate reduction, principal forgiveness, deferral or decrease in payments for a period of time and other actions intended to minimize the economic loss and to avoid foreclosure or repossession of collateral. Consistent with the CARES Act and interagency bank regulatory guidance which allows temporary relief for current borrowers affected by COVID-19, we are working with borrowers and granting certain modifications through programs related to COVID-19 relief. As of March 31, 2021, we had $269 million in loans that have been granted short-term modifications as a result of financial disruptions associated with the COVID-19 pandemic. Also, consistent with the CARES Act and the interagency bank regulatory guidelines, such modifications are not included in our TDR totals. Following is a summary of the composition of total TDRs: TABLE 4.7 (in millions) March 31, December 31, Accruing $ 58 $ 58 Non-accrual 40 33 Total TDRs $ 98 $ 91 TDRs that are accruing and performing include loans that met the criteria for non-accrual of interest prior to restructuring for which we can reasonably estimate the timing and amount of the expected cash flows on such loans and for which we expect to fully collect the new carrying value of the loans. During the three months ended March 31, 2021, we returned to accruing status $3.9 million in restructured residential mortgage loans that have consistently met their modified obligations for more than six months. TDRs that are on non-accrual are not placed on accruing status until all delinquent principal and interest have been paid and the ultimate collectability of the remaining principal and interest is reasonably assured. Some loan modifications classified as TDRs may not ultimately result in the full collection of principal and interest, as modified, and may result in potential incremental losses which are factored into the ACL. Commercial loans over $1.0 million whose terms have been modified in a TDR are generally placed on non-accrual, individually analyzed and measured based on the fair value of the underlying collateral. Our ACL includes specific reserves for commercial TDRs of $1.6 million at March 31, 2021 compared to $2.8 million at December 31, 2020, and pooled reserves for individual loans of $2.5 million for those same periods based on loan segment LGD. Upon default, the amount of the recorded investment in the TDR in excess of the fair value of the collateral, less estimated selling costs, is generally considered a confirmed loss and is charged-off against the ACL. All other classes of loans whose terms have been modified in a TDR are pooled and measured based on the loan segment LGD. Our ACL included pooled reserves for these classes of loans of $3.9 million for March 31, 2021 and $4.1 million for December 31, 2020. Upon default of an individual loan, our charge-off policy is followed for that class of loan. Following is a summary of TDR loans, by class, for loans that were modified during the periods indicated: TABLE 4.8 Three Months Ended March 31, 2021 (dollars in millions) Number Pre- Post- Commercial real estate 11 $ 17 $ 17 Commercial and industrial 1 — — Total commercial loans 12 17 17 Direct installment 10 — — Residential mortgages 2 1 1 Consumer lines of credit 10 1 1 Total consumer loans 22 2 2 Total 34 $ 19 $ 19 Three Months Ended March 31, 2020 (dollars in millions) Number Pre- Post- Commercial real estate 5 $ 1 $ 1 Commercial and industrial 7 1 — Total commercial loans 12 2 1 Direct installment 19 2 2 Residential mortgages 14 1 1 Consumer lines of credit 15 — — Total consumer loans 48 3 3 Total 60 $ 5 $ 4 The year-to-date items in the above tables have been adjusted for loans that have been paid off and/or sold. Following is a summary of TDRs, by class, for which there was a payment default, excluding loans that have been paid off and/or sold. Default occurs when a loan is 90 days or more past due and is within 12 months of restructuring. TABLE 4.9 Three Months Ended (dollars in millions) Number of Recorded Commercial and industrial 1 $ — Total commercial loans 1 — Residential mortgages 1 — Total consumer loans 1 — Total 2 $ — Three Months Ended (dollars in millions) Number of Recorded Commercial real estate 10 $ 4 Commercial and industrial 2 — Total commercial loans 12 4 Direct installment 4 — Residential mortgages 1 — Total consumer loans 5 — Total 17 $ 4

ALLOWANCE FOR CREDIT LOSSES ON

ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES	ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES Beginning January 1, 2020, the former incurred loss method was replaced with the CECL method to calculate estimated loan losses. The CECL model takes into consideration the expected credit losses over the expected life of the loan compared to the incurred loss model under the prior standard. At the time of CECL adoption, we recorded a one-time cumulative-effect adjustment of $50.6 million as a reduction to Retained Earnings. The ACL balance increased by $105 million and included a “gross-up" to purchased credit impaired (PCD under CECL) loan balances and the ACL of $50 million. Included in the CECL adoption impact was a Day 1 increase to our AULC of $10 million. The ACL addresses credit losses expected in the existing loan and lease portfolio and is presented as a reserve against loans and leases on the Consolidated Balance Sheets. Loan and lease losses are charged off against the ACL, with recoveries of amounts previously charged off credited to the ACL. Provisions for credit losses are charged to operations based on management’s periodic evaluation of the appropriate level of the ACL. Included in Table 5.1 is the impact to the ACL from our CECL (ASC 326) adoption on January 1, 2020. Following is a summary of changes in the ACL, by loan and lease class: TABLE 5.1 (in millions) Balance at Charge- Recoveries Net Provision for Credit Losses Balance at Three Months Ended March 31, 2021 Commercial real estate $ 181 $ (1) $ 1 $ — $ 3 $ 184 Commercial and industrial 81 (8) 1 (7) 5 79 Commercial leases 17 — 1 1 (1) 17 Other 1 (1) 1 — — 1 Total commercial loans and leases 280 (10) 4 (6) 7 281 Direct installment 26 — — — — 26 Residential mortgages 34 — — — (2) 32 Indirect installment 11 (2) 1 (1) 1 11 Consumer lines of credit 12 — — — — 12 Total consumer loans 83 (2) 1 (1) (1) 81 Total allowance for credit losses on loans and leases 363 (12) 5 (7) 6 362 Allowance for unfunded loan commitments 14 — — — — 14 Total allowance for credit losses on loans and leases and allowance for unfunded loan commitments $ 377 $ (12) $ 5 $ (7) $ 6 $ 376 (in millions) Balance at Charge- Recoveries Net Provision ASC 326 Adoption Impact Initial ACL on PCD Loans Balance at Three Months Ended March 31, 2020 Commercial real estate $ 60 $ (2) $ 4 $ 2 $ 12 $ 38 $ 40 $ 152 Commercial and industrial 53 (4) 1 (3) 26 8 4 88 Commercial leases 11 — — — 2 — — 13 Other 9 (1) — (1) 2 (9) — 1 Total commercial loans and leases 133 (7) 5 (2) 42 37 44 254 Direct installment 13 (1) — (1) 3 10 1 26 Residential mortgages 22 — — — (1) 6 4 31 Indirect installment 19 (3) 1 (2) 2 2 — 21 Consumer lines of credit 9 (1) — (1) 2 — 1 11 Total consumer loans 63 (5) 1 (4) 6 18 6 89 Total allowance for credit losses on loans and leases 196 (12) 6 (6) 48 55 50 343 Allowance for unfunded loan commitments (1) 3 — — — 1 10 — 14 Total allowance for credit losses on loans and leases and allowance for unfunded loan commitments $ 199 $ (12) $ 6 $ (6) $ 49 $ 65 $ 50 $ 357 (1) The $1 million provision for the AULC is included in other non-interest expense on the Consolidated Statements of Income. Following is a summary of changes in the AULC by portfolio segment: TABLE 5.2 Three Months Ended 2021 2020 (in millions) Balance at beginning of period $ 14 $ 3 Provision for unfunded loan commitments and letters of credit: Commercial portfolio — — Consumer portfolio — — Other adjustments: Commercial portfolio — 1 ASC 326 adoption impact: Commercial portfolio — 8 Consumer portfolio — 2 Balance at end of period $ 14 $ 14 The model used to calculate the ACL is dependent on the portfolio composition and credit quality, as well as historical experience, current conditions and forecasts of economic conditions and interest rates. Specifically, the following considerations are incorporated into the ACL calculation: • a third-party macroeconomic forecast scenario; • a 24-month R&S forecast period for macroeconomic factors with a reversion to the historical mean on a straight-line basis over a 12-month period; and • the historical through-the-cycle mean was calculated using an expanded period to include a prior recessionary period. COVID-19 Impacts on the ACL Beginning in March 2020, the broader economy experienced a significant deterioration in the macroeconomic environment driven by the COVID-19 pandemic resulting in notable adverse changes to forecasted economic variables utilized in our ACL modeling process. Based on these changes, we utilized a third-party pandemic recessionary scenario from the first quarter of 2020 through the third quarter of 2020 for ACL modeling purposes. At December 31, 2020 and March 31, 2021, we utilized a third-party consensus macroeconomic forecast due to the improving macroeconomic environment. Macroeconomic variables that we utilized from this scenario for our ACL calculation as of December 31, 2020 included, but were not limited to: (i) gross domestic product, which reflects growth of 4% in 2021, (ii) the Dow Jones Total Stock Market Index, which grows steadily throughout the R&S forecast period, (iii) unemployment, which steadily declines and averages 6% over the R&S forecast period and (iv) the Volatility Index, which remains stable over the R&S forecast period. For our ACL calculation at March 31, 2021, the macroeconomic variables that we utilized included, but were not limited to: (i) gross domestic product, which reflects growth of 6% in 2021 and 2% in 2022, (ii) the Dow Jones Total Stock Market Index, which remains relatively flat through the R&S forecast period, (iii) unemployment, which averages 5% over the R&S forecast period and (iv) the Volatility Index, which remains stable over the R&S forecast period.

LOAN SERVICING

LOAN SERVICING	3 Months Ended
	Mar. 31, 2021
Transfers and Servicing [Abstract]
LOAN SERVICING	LOAN SERVICING Mortgage Loan Servicing We retain the servicing rights on certain mortgage loans sold. The unpaid principal balance of mortgage loans serviced for others is listed below: TABLE 6.1 (in millions) March 31, December 31, Mortgage loans sold with servicing retained $ 4,670 $ 4,653 The following table summarizes activity relating to mortgage loans sold with servicing retained: TABLE 6.2 Three Months Ended (in millions) 2021 2020 Mortgage loans sold with servicing retained $ 506 $ 260 Pretax net gains resulting from above loan sales (1) 17 7 Mortgage servicing fees (1) 3 3 (1) Recorded in mortgage banking operations on the Consolidated Statements of Income. Following is a summary of activity relating to MSRs: TABLE 6.3 Three Months Ended (in millions) 2021 2020 Balance at beginning of period $ 35.6 $ 42.6 Additions 5.2 2.5 Payoffs and curtailments (4.1) (1.9) (Impairment charge) / recovery 2.5 (7.7) Amortization (0.6) (0.6) Balance at end of period $ 38.6 $ 34.9 Fair value, beginning of period $ 35.6 $ 45.0 Fair value, end of period 40.2 34.9 We had a $4.8 million valuation allowance for MSRs as of March 31, 2021, compared to $7.3 million at December 31, 2020. The fair value of MSRs is highly sensitive to changes in assumptions and is determined by estimating the present value of the asset’s future cash flows utilizing market-based prepayment rates, discount rates and other assumptions validated through comparison to trade information, industry surveys and with the use of independent third-party valuations. Changes in prepayment speed assumptions have the most significant impact on the fair value of MSRs. Generally, as interest rates decline, mortgage loan prepayments accelerate due to increased refinance activity, which results in a decrease in the fair value of MSRs and as interest rates increase, mortgage loan prepayments decline, which results in an increase in the fair value of MSRs. Measurement of fair value is limited to the conditions existing and the assumptions utilized as of a particular point in time, and those assumptions may not be appropriate if they are applied at a different time. Following is a summary of the sensitivity of the fair value of MSRs to changes in key assumptions: TABLE 6.4 (dollars in millions) March 31, December 31, Weighted average life (months) 71.3 66.6 Constant prepayment rate (annualized) 12.6 % 13.4 % Discount rate 9.5 % 9.5 % Effect on fair value due to change in interest rates: +0.25% $ 3 $ 2 +0.50% 5 4 -0.25% (3) (2) -0.50% (6) (3) The sensitivity calculations above are hypothetical and should not be considered to be predictive of future performance. Changes in fair value based on adverse changes in assumptions generally cannot be extrapolated because the relationship of the changes in assumptions to fair value may not be linear. Also, in this table, the effects of an adverse variation in a particular assumption on the fair value of MSRs is calculated without changing any other assumptions, while in reality, changes in one factor may result in changing another, which may magnify or contract the effect of the change.

OPERATING LEASES

OPERATING LEASES	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
OPERATING LEASES	OPERATING LEASES We have operating leases primarily for certain branches, office space, land and office equipment. Our operating leases expire at various dates through the year 2046 and generally include one or more options to renew. The exercise of lease renewal options is at our sole discretion. As of March 31, 2021, we had operating lease right-of-use assets operating lease liabilities Our operating lease agreements do not contain any material residual value guarantees or material restrictive covenants. As of March 31, 2021, we have certain operating lease agreements, primarily for administrative office space, that have not yet commenced. At commencement, it is expected that these leases will add approximately $21.5 million in right-of-use assets and other liabilities. These operating leases are currently expected to commence in 2021 with lease terms of 3 years to 20 years. The components of lease expense were as follows: TABLE 7.1 Three Months Ended (dollars in millions) 2021 2020 Operating lease cost $ 7 $ 7 Variable lease cost 1 1 Total lease cost $ 8 $ 8 Other information related to leases is as follows: TABLE 7.2 Three Months Ended (dollars in millions) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 7 $ 6 Right-of-use assets obtained in exchange for lease obligations: Operating leases — 4 Weighted average remaining lease term (years): Operating leases 9.39 9.64 Weighted average discount rate: Operating leases 2.6 % 2.9 % Maturities of operating lease liabilities were as follows: TABLE 7.3 (in millions) March 31, 2021 $ 19 2022 22 2023 17 2024 16 2025 12 Later years 64 Total lease payments 150 Less: imputed interest (20) Present value of lease liabilities $ 130 As a lessor we offer commercial leasing services to customers in need of new or used equipment primarily within our market areas of Pennsylvania, Ohio, Maryland, North Carolina, South Carolina and West Virginia. Additional information relating to commercial leasing is provided in Note 4, “Loans and Leases” in the Notes to Consolidated Financial Statements.

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
VARIABLE INTEREST ENTITIES	VARIABLE INTEREST ENTITIES We evaluate our interest in certain entities to determine if these entities meet the definition of a VIE and whether we are the primary beneficiary and required to consolidate the entity based on the variable interest we held both at inception and when there is a change in circumstances that requires a reconsideration. Unconsolidated VIEs The following table provides a summary of the assets and liabilities included in our Consolidated Financial Statements, as well as the maximum exposure to losses, associated with our interests related to VIEs for which we hold an interest, but are not the primary beneficiary, at March 31, 2021 and December 31, 2020. TABLE 8.1 (in millions) Total Assets Total Liabilities Maximum Exposure to Loss March 31, 2021 Trust preferred securities (1) $ 1 $ 66 $ — Affordable housing tax credit partnerships 115 41 115 Other investments 26 7 26 Total $ 142 $ 114 $ 141 December 31, 2020 Trust preferred securities (1) $ 1 $ 66 $ — Affordable housing tax credit partnerships 119 45 119 Other investments 26 8 26 Total $ 146 $ 119 $ 145 (1) Represents our investment in unconsolidated subsidiaries. Trust-Preferred Securities We have certain wholly-owned trusts whose assets, liabilities, equity, income and expenses are not included within our Consolidated Financial Statements. These trusts have been formed for the sole purpose of issuing TPS, from which the proceeds are then invested in our junior subordinated debentures, which are reflected in our Consolidated Balance Sheets as subordinated notes. The TPS are the obligations of the trusts, and as such, are not consolidated within our Consolidated Financial Statements. For additional information relating to our TPS, see Note 9, “Borrowings” in the Notes to Consolidated Financial Statements. Each issue of the junior subordinated debentures has an interest rate equal to the corresponding TPS distribution rate. We have 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 TPS will also be deferred and our ability to pay dividends on our common stock will be restricted. Periodic cash payments and payments upon liquidation or redemption with respect to TPS are guaranteed by us to the extent of funds held by the trusts. The guarantee ranks subordinate and junior in right of payment to all of our indebtedness 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 us. Affordable Housing Tax Credit Partnerships We make equity investments as a limited partner in various partnerships that sponsor affordable housing projects utilizing the LIHTC pursuant to Section 42 of the Internal Revenue Code. The purpose of these investments is to support initiatives associated with the Community Reinvestment Act while earning a satisfactory return. The activities of these LIHTC partnerships include the development and operation of multi-family housing that is leased to qualifying residential tenants. These partnerships are generally located in communities where we have a banking presence and meet the definition of a VIE; however, we are not the primary beneficiary of the entities, as the general partner or managing member has both the power to direct the activities that most significantly impact the economic performance of the entities and the obligation to absorb losses beyond our own equity investment. We record our investment in LIHTC partnerships as a component of other assets. We use the proportional amortization method to account for a majority of our investments in LIHTC partnerships. Investments that do not meet the requirements of the proportional amortization method are recognized using the equity method. Amortization related to investments under the proportional amortization method are recorded on a net basis as a component of the provision of income taxes on the Consolidated Statements of Income, while write-downs and losses related to investments under the equity method are included in non-interest expense. The following table presents the balances of our affordable housing tax credit investments and related unfunded commitments: TABLE 8.2 (in millions) March 31, December 31, Proportional amortization method investments included in other assets $ 71 $ 71 Equity method investments included in other assets 3 3 Total LIHTC investments included in other assets $ 74 $ 74 Unfunded LIHTC commitments $ 41 $ 45 The following table summarizes the impact of these LIHTC investments on specific line items of our Consolidated Statements of Income: TABLE 8.3 Three Months Ended (in millions) 2021 2020 Non-interest income: Amortization of tax credit investments under equity method, net of tax benefit $ — $ — Provision for income taxes: Amortization of LIHTC investments under proportional method $ 3 $ 3 Low-income housing tax credits (3) (3) Other tax benefits related to tax credit investments (1) (1) Total provision for income taxes $ (1) $ (1) Other Investments Other investments we also consider to be unconsolidated VIE’s include investments in Small Business Investment Companies, Historic Tax Credit Investments, and other equity method investments.

BORROWINGS

BORROWINGS	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
BORROWINGS	BORROWINGS Following is a summary of short-term borrowings: TABLE 9.1 (in millions) March 31, December 31, Securities sold under repurchase agreements $ 435 $ 403 Federal Home Loan Bank advances 1,130 1,280 Subordinated notes 122 121 Total short-term borrowings $ 1,687 $ 1,804 Borrowings with original maturities of one year or less are classified as short-term. Securities sold under repurchase agreements are comprised of customer repurchase agreements, which are sweep accounts with next-day maturities utilized by larger commercial customers to earn interest on their funds. Securities are pledged to these customers in an amount at least equal to the outstanding balance. We did not have any short-term FHLB advances with overnight maturities as of March 31, 2021 or December 31, 2020. At March 31, 2021, $1.1 billion, or 100.0%, of the short-term FHLB advances were swapped to a fixed rate with maturities in 2021. This compares to $1.3 billion, or 100.0%, as of December 31, 2020. Following is a summary of long-term borrowings: TABLE 9.2 (in millions) March 31, December 31, Federal Home Loan Bank advances $ 400 $ 400 Senior notes 299 299 Subordinated notes 78 81 Junior subordinated debt 66 66 Other subordinated debt 248 249 Total long-term borrowings $ 1,091 $ 1,095 Our banking affiliate has available credit with the FHLB of $8.3 billion, of which $1.5 billion was utilized as of March 31, 2021. These advances are secured by loans collateralized by residential mortgages, home equity lines of credit, commercial real estate and FHLB stock and are scheduled to mature in various amounts periodically through the year 2021. Effective interest rates paid on the long-term advances ranged from 0.26% to 0.29% for the three months ended March 31, 2021 and 0.30% to 0.34% for the year ended December 31, 2020. The following table provides information relating to our senior debt and other subordinated debt as of March 31, 2021. These debt issuances are fixed-rate, with the exception of the debt offering in 2019, which is fixed-to-floating rate after February 14, 2024. The subordinated notes are eligible for treatment as tier 2 capital for regulatory capital purposes. TABLE 9.3 (dollars in millions) Aggregate Principal Amount Issued Net Proceeds (2) Carrying Value Stated Maturity Date Interest 2.20% Senior Notes due February 24, 2023 $ 300 $ 298 $ 299 2/24/2023 2.20 % 4.95% Fixed-To-Floating Rate Subordinated Notes due 2029 120 118 118 2/14/2029 4.95 % 4.875% Subordinated Notes due 2025 100 98 99 10/2/2025 4.875 % 7.625% Subordinated Notes due August 12, 2023 (1) 38 46 31 8/12/2023 7.625 % Total $ 558 $ 560 $ 547 (1) Assumed from a prior acquisition and adjusted to fair value at the time of acquisition. (2) After deducting underwriting discounts and commissions and offering costs. For the debt assumed from a prior acquisition, this is the fair value of the debt at the time of the acquisition. The junior subordinated debt is comprised of the debt securities issued by FNB in relation to our unconsolidated subsidiary trusts (collectively, the Trusts), which are unconsolidated VIEs, and are included on the Consolidated Balance Sheets in long-term borrowings. Since third-party investors are the primary beneficiaries, the Trusts are not consolidated in our Financial Statements. We record the distributions on the junior subordinated debt issued to the Trusts as interest expense. The following table provides information relating to the Trusts as of March 31, 2021: TABLE 9.4 (dollars in millions) Trust Common Junior Stated Interest Rate Rate Reset Factor F.N.B. Statutory Trust II $ 22 $ 1 $ 22 6/15/2036 1.83 % LIBOR + 165 basis points (bps) Yadkin Valley Statutory Trust I 25 1 22 12/15/2037 1.50 % LIBOR + 132 bps FNB Financial Services Capital Trust I 25 1 22 9/30/2035 1.66 % LIBOR + 146 bps Total $ 72 $ 3 $ 66

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES We are exposed to certain risks arising from both our business operations and economic conditions. We principally manage our exposures to a wide variety of business and operational risks through management of our core business activities. We manage economic risks, including interest rate risk, primarily by managing the amount, source, and duration of our assets and liabilities, and through the use of derivative instruments. Derivative instruments are used to reduce the effects that changes in interest rates may have on net income and cash flows. We also use derivative instruments to facilitate transactions on behalf of our customers. All derivatives are carried on the Consolidated Balance Sheets at fair value and do not take into account the effects of master netting arrangements we have with other financial institutions. Credit risk is included in the determination of the estimated fair value of derivatives. Derivative assets are reported in the Consolidated Balance Sheets in other assets and derivative liabilities are reported in other liabilities. Changes in fair value are recognized in earnings except for certain changes related to derivative instruments designated as part of a cash flow hedging relationship. The following table presents notional amounts and gross fair values of our derivative assets and derivative liabilities which are not offset in the Consolidated Balance Sheets: TABLE 10.1 March 31, 2021 December 31, 2020 Notional Fair Value Notional Fair Value (in millions) Amount Asset Liability Amount Asset Liability Gross Derivatives Subject to master netting arrangements: Interest rate contracts – designated $ 1,180 $ 2 $ — $ 1,430 $ 3 $ — Interest rate swaps – not designated 4,947 4 25 4,791 — 37 Total subject to master netting arrangements 6,127 6 25 6,221 3 37 Not subject to master netting arrangements: Interest rate swaps – not designated 4,947 211 32 4,791 349 — Interest rate lock commitments – not designated 549 10 1 531 24 — Forward delivery commitments – not designated 571 9 — 500 — 2 Credit risk contracts – not designated 425 — 1 437 — 1 Total not subject to master netting arrangements 6,492 230 34 6,259 373 3 Total $ 12,619 $ 236 $ 59 $ 12,480 $ 376 $ 40 Certain derivative exchanges have enacted a rule change which in effect results in the legal characterization of variation margin payments for certain derivative contracts as settlement of the derivatives mark-to-market exposure and not collateral. Accordingly, we have changed our reporting of certain derivatives to record variation margin on trades cleared through these exchanges as settled. The daily settlement of the derivative exposure does not change or reset the contractual terms of the instrument. The fair value of interest rate swaps - not designated has increased from December 31, 2020 primarily due to the significantly lower interest rate environment since year-end. We adopted RRR on October 1, 2020, and the guidance will be followed until the Update terminates on December 31, 2022. As of October 16, 2020, we changed our valuation methodology to reflect changes made by central clearinghouses that changed the discounting methodology and interest calculation of cash migration from overnight index swap (OIS) to SOFR for U.S. dollar cleared interest rate swaps to better reflect prices obtainable in the markets in which we transact. Certain of these valuation methodology changes were applied to eligible hedging relationships. Accordingly, we have updated our hedge documentation to reflect the election of certain expedients and exceptions related to our cash flow hedging programs. The change in valuation methodology was applied prospectively as a change in accounting estimate and did not have a material impact on our consolidated financial position or results of operations. Derivatives Designated as Hedging Instruments under GAAP Interest Rate Contracts. We entered into interest rate derivative agreements to modify the interest rate characteristics of certain commercial loans and certain of our FHLB advances from variable rate to fixed rate in order to reduce the impact of changes in future cash flows due to market interest rate changes. These agreements are designated as cash flow hedges, hedging the exposure to variability in expected future cash flows. The derivative’s gain or loss, including any ineffectiveness, is initially reported as a component of other comprehensive income and subsequently reclassified into earnings in the same line item associated with the forecasted transaction when the forecasted transaction affects earnings. The following table shows amounts reclassified from AOCI: TABLE 10.2 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from AOCI into Income Amount of Gain (Loss) Reclassified from AOCI into Income Three Months Ended Three Months Ended (in millions) 2021 2020 2021 2020 Derivatives in cash flow hedging relationships: Interest rate contracts $ 5 $ (45) Interest income (expense) $ (5) $ (1) The following table represents gains (losses) recognized in the Consolidated Statements of Income on cash flow hedging relationships: TABLE 10.3 Three months ended March 31, 2021 2020 (in millions) Interest Income - Loans and Leases Interest Expense - Short-Term Borrowings Interest Income - Loans and Leases Interest Expense - Short-Term Borrowings Total amounts of income and expense line items presented in the Consolidated Statements of Income (the effects of cash flow hedges are included in these line items) $ 221 $ 7 $ 266 $ 14 The effects of cash flow hedging: Gain (loss) on cash flow hedging relationships: Interest rate contracts: Amount of gain (loss) reclassified from AOCI into net income — (5) — (1) As of March 31, 2021, the maximum length of time over which forecasted interest cash flows are hedged is 3.6 years. In the twelve months that follow March 31, 2021, we expect to reclassify from the amount currently reported in AOCI net derivative losses of $18.0 million ($14.0 million net of tax), in association with interest on the hedged loans and FHLB advances. This amount could differ from amounts actually recognized due to changes in interest rates, hedge de-designations, and the addition of other hedges subsequent to March 31, 2021. There were no components of derivative gains or losses excluded from the assessment of hedge effectiveness related to these cash flow hedges. Also, during the three months ended March 31, 2021 and 2020, there were no gains or losses from cash flow hedge derivatives reclassified to earnings because it became probable that the original forecasted transactions would not occur. Derivatives Not Designated as Hedging Instruments under GAAP A description of interest rate swaps, interest rate lock commitments, forward delivery commitments and credit risk contracts can be found in Note 15, "Derivative Instruments and Hedging Activities" in the Consolidated Financial Statements included in our 2020 Annual Report on Form 10-K filed with the SEC on February 25, 2021. Interest rate swap agreements with loan customers and with the offsetting counterparties are reported at fair value in other assets and other liabilities on the Consolidated Balance Sheets with any resulting gain or loss recorded in current period earnings as other income or other expense. Risk participation agreements sold with notional amounts totaling $291.9 million as of March 31, 2021 have remaining terms ranging from one month to twenty years. Under these agreements, our maximum exposure assuming a customer defaults on their obligation to perform under certain derivative swap contracts with third parties would be $0.3 million at March 31, 2021 and $0.6 million at December 31, 2020. The fair values of risk participation agreements purchased and sold were $0.1 million and $0.3 million, respectively, at March 31, 2021 and $0.2 million and $0.6 million, respectively at December 31, 2020. The following table presents the effect of certain derivative financial instruments on the Consolidated Statements of Income: TABLE 10.4 Three Months Ended (in millions) Consolidated Statements of Income Location 2021 2020 Interest rate swaps Non-interest income - other $ — $ — Interest rate lock commitments Mortgage banking operations — — Forward delivery contracts Mortgage banking operations 9 (1) Credit risk contracts Non-interest income - other — — Counterparty Credit Risk We are party to master netting arrangements with most of our swap derivative dealer counterparties. Collateral, usually marketable securities and/or cash, is exchanged between FNB and our counterparties, and is generally subject to thresholds and transfer minimums. For swap transactions that require central clearing, we post cash to our clearing agency. Collateral positions are settled or valued daily, and adjustments to amounts received and pledged by us are made as appropriate to maintain proper collateralization for these transactions. Certain master netting agreements contain provisions that, if violated, could cause the counterparties to request immediate settlement or demand full collateralization under the derivative instrument. If we had breached our agreements with our derivative counterparties we would be required to settle our obligations under the agreements at the termination value and would be required to pay an additional $0.1 million and $0.3 million as of March 31, 2021 and December 31, 2020, respectively, in excess of amounts previously posted as collateral with the respective counterparty. The following table presents a reconciliation of the net amounts of derivative assets and derivative liabilities presented in the Consolidated Balance Sheets to the net amounts that would result in the event of offset: TABLE 10.5 Amount Not Offset in the (in millions) Net Amount Financial Cash Net March 31, 2021 Derivative Assets Interest rate contracts: Designated $ 2 $ — $ 2 $ — Not designated 4 — 4 — Total $ 6 $ — $ 6 $ — Derivative Liabilities Interest rate contracts: Not designated $ 25 $ — $ 25 $ — Total $ 25 $ — $ 25 $ — December 31, 2020 Derivative Assets Interest rate contracts: Designated $ 3 $ — $ 3 $ — Total $ 3 $ — $ 3 $ — Derivative Liabilities Interest rate contracts: Not designated $ 37 $ — $ 37 $ — Total $ 37 $ — $ 37 $ —

COMMITMENTS, CREDIT RISK AND CO

COMMITMENTS, CREDIT RISK AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS, CREDIT RISK AND CONTINGENCIES	COMMITMENTS, CREDIT RISK AND CONTINGENCIES We have commitments to extend credit and standby letters of credit that involve certain elements of credit risk in excess of the amount stated in the Consolidated Balance Sheets. Our exposure to credit loss in the event of non-performance by the customer is represented by the contractual amount of those instruments. The credit risk associated with commitments to extend credit and standby letters of credit is essentially the same as that involved in extending loans and leases to customers and is subject to normal credit policies. Since many of these commitments expire without being drawn upon, the total commitment amounts do not necessarily represent future cash flow requirements. Following is a summary of off-balance sheet credit risk information: TABLE 11.1 (in millions) March 31, December 31, Commitments to extend credit $ 9,806 $ 9,285 Standby letters of credit 168 158 At March 31, 2021, funding of 74.6% of the commitments to extend credit was dependent on the financial condition of the customer. We have the ability to withdraw such commitments at our discretion. Commitments generally have fixed expiration dates or other termination clauses and may require payment of a fee. Based on management’s credit evaluation of the customer, collateral may be deemed necessary. Collateral requirements vary and may include accounts receivable, inventory, property, plant and equipment and income-producing commercial properties. Standby letters of credit are conditional commitments issued by us that may require payment at a future date. The credit risk involved in issuing letters of credit is actively monitored through review of the historical performance of our portfolios. Our AULC for commitments that are not unconditionally cancellable, which is included in other liabilities on the Consolidated Balance Sheets, was $13.5 million at March 31, 2021. Additional information relating to the AULC is provided in Note 5, "Allowance for Credit Losses on Loans and Leases" in the Notes to Consolidated Financial Statements. In addition to the above commitments, subordinated notes issued by FNB Financial Services, LP, a wholly-owned finance subsidiary, are fully and unconditionally guaranteed by FNB. These subordinated notes are included in the summaries of short-term borrowings and long-term borrowings in Note 9, “Borrowings” in the Notes to Consolidated Financial Statements. Other Legal Proceedings In the ordinary course of business, we may assert claims in legal proceedings against another party or parties, and we are routinely named as defendants in, or made parties to, pending and potential legal actions. Also, as regulated entities, we are subject to governmental and regulatory examinations, information-gathering requests, and may be subject to investigations and proceedings (both formal and informal). Such threatened claims, litigation, investigations, regulatory and administrative proceedings typically entail matters that are considered incidental to the normal conduct of business. Claims for significant monetary damages may be asserted in many of these types of legal actions, while claims for disgorgement, restitution, penalties and/or other remedial actions or sanctions may be sought in regulatory matters. In these instances, if we determine that we have meritorious defenses, we will engage in an aggressive defense. However, if management determines, in consultation with counsel, that settlement of a matter is in the best interest of FNB and our shareholders, we may do so. It is inherently difficult to predict the eventual outcomes of such matters given their complexity and the particular facts and circumstances at issue in each of these matters. However, on the basis of current knowledge and understanding, and advice of counsel, we do not believe that judgments, sanctions, settlements or orders, if any, that may arise from these matters (either individually or in the aggregate, after giving effect to applicable reserves and insurance coverage) will have a material adverse effect on our financial position or liquidity, although they could have a material effect on net income in a given period. In view of the inherent unpredictability of outcomes in litigation and governmental and regulatory matters, particularly where (i) the damages sought are indeterminate, (ii) the proceedings are in the early stages, or (iii) the matters involve novel legal theories or a large number of parties, as a matter of course, there is considerable uncertainty surrounding the timing or ultimate resolution of litigation and governmental and regulatory matters, including a possible eventual loss, fine, penalty, business or adverse reputational impact, if any, associated with each such matter. In accordance with applicable accounting guidance, we establish accruals for litigation and governmental and regulatory matters when those matters proceed to a stage where they present loss contingencies that are both probable and reasonably estimable. In such cases, there may be a possible exposure to loss in excess of any amounts accrued. We will continue to monitor such matters for developments that could affect the amount of the accrual, and will adjust the accrual amount as appropriate. If the loss contingency in question is not both probable and reasonably estimable, we do not establish an accrual and the matter will continue to be monitored for any developments that would make the loss contingency both probable and reasonably estimable. We believe that our accruals for legal proceedings are appropriate and, in the aggregate, are not material to our consolidated financial position, although future accruals could have a material effect on net income in a given period.

STOCK INCENTIVE PLANS

STOCK INCENTIVE PLANS	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
STOCK INCENTIVE PLANS	STOCK INCENTIVE PLANS Restricted Stock We issue restricted stock awards to key employees under our Incentive Compensation Plan (Plan). We issue time-based awards and performance-based awards under this Plan, both of which are based on a three-year vesting period. The grant date fair value of the time-based awards is equal to the price of our common stock on the grant date. The fair value of the performance-based awards is based on a Monte-Carlo simulation valuation of our common stock as of the grant date. The assumptions used for this valuation include stock price volatility, risk-free interest rate and dividend yield. We issued 542,136 and 1,988,225 restricted stock units during the three months ended March 31, 2021 and 2020, respectively, including 325,284 and 571,932 performance-based restricted stock units during those same periods, respectively. As of March 31, 2021, we had available up to 5,362,034 shares of common stock to issue under this Plan, which includes 4,640,000 additional shares registered during the third quarter of 2020. The unvested restricted stock unit awards are eligible to receive cash dividends or dividend equivalents which are ultimately used to purchase additional shares of stock and are subject to forfeiture if the requisite service period is not completed or the specified performance criteria are not met. These awards are subject to certain accelerated vesting provisions upon retirement, death, disability or in the event of a change of control as defined in the award agreements. The following table summarizes the activity relating to restricted stock units during the periods indicated: TABLE 12.1 Three Months Ended March 31, 2021 2020 Units Weighted Units Weighted Unvested units outstanding at beginning of period 4,322,115 $ 9.46 2,858,357 $ 12.56 Granted 542,136 12.61 1,988,225 6.95 Net adjustment due to performance 327,256 11.84 — — Vested (142,687) 7.29 (1,717) 14.15 Forfeited/expired (8,334) 7.52 (11,362) 12.85 Dividend reinvestment 42,310 13.43 39,865 8.57 Unvested units outstanding at end of period 5,082,796 10.05 4,873,368 10.23 The following table provides certain information related to restricted stock units: TABLE 12.2 (in millions) Three Months Ended 2021 2020 Stock-based compensation expense $ 12 $ 8 Tax benefit related to stock-based compensation expense 3 2 Fair value of units vested 1 — As of March 31, 2021, there was $10.0 million of unrecognized compensation cost related to unvested restricted stock units, including $1.2 million that is subject to accelerated vesting under the Plan’s immediate vesting upon retirement. The components of the restricted stock units as of March 31, 2021 are as follows: TABLE 12.3 (dollars in millions) Service- Performance- Total Unvested restricted stock units 3,076,326 2,006,470 5,082,796 Unrecognized compensation expense $ 7 $ 3 $ 10 Intrinsic value $ 39 $ 25 $ 64 Weighted average remaining life (in years) 1.64 1.27 1.49 Stock Options All outstanding stock options were assumed from acquisitions and are fully vested. Upon consummation of our acquisitions, all outstanding stock options issued by the acquired companies were converted into equivalent FNB stock options. We issue shares of treasury stock or authorized but unissued shares to satisfy stock options exercised. As of March 31, 2021, we had 182,747 stock options outstanding and exercisable at a weighted average exercise price per share of $8.86, compared to 231,646 stock options outstanding and exercisable at a weighted average exercise price per share of $8.22 as of March 31, 2020. The intrinsic value of outstanding and exercisable stock options at March 31, 2021 was $0.7 million. The aggregate intrinsic value represents the amount by which the fair value of underlying stock exceeds the option exercise price.

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Income Tax Expense Federal and state income tax expense and the statutory tax rate and the actual effective tax rate consist of the following: TABLE 13.1 Three Months Ended (in millions) 2021 2020 Current income taxes: Federal taxes $ 21 $ 7 State taxes 2 2 Total current income taxes 23 9 Deferred income taxes: Federal taxes (1) 2 State taxes — — Total deferred income taxes (1) 2 Total income taxes $ 22 $ 11 Statutory tax rate 21.0 % 21.0 % Effective tax rate 18.9 % 18.8 % The effective tax rates for the three months ended March 31, 2021 and March 31, 2020 were lower than the statutory federal tax rate primarily due to tax benefits resulting from tax-exempt income on investments and loans, tax credits and income from BOLI. Deferred Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and tax purposes. Deferred tax assets and liabilities are measured based on the enacted tax rates that will apply in the years in which the temporary differences are expected to be recovered or paid. Net deferred tax assets were $56.1 million and $51.0 million at March 31, 2021 and December 31, 2020, respectively.

OTHER COMPREHENSIVE INCOME

OTHER COMPREHENSIVE INCOME	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
OTHER COMPREHENSIVE INCOME	OTHER COMPREHENSIVE INCOME The following table presents changes in AOCI, net of tax, by component: TABLE 14.1 (in millions) Unrealized Unrealized Unrecognized Total Three Months Ended March 31, 2021 Balance at beginning of period $ 65 $ (40) $ (64) $ (39) Other comprehensive (loss) income before reclassifications (21) 4 1 (16) Amounts reclassified from AOCI — 4 — 4 Net current period other comprehensive (loss) income (21) 8 1 (12) Balance at end of period $ 44 $ (32) $ (63) $ (51) The amounts reclassified from AOCI related to debt securities AFS are included in net securities gains on the Consolidated Statements of Income, while the amounts reclassified from AOCI related to derivative instruments in cash flow hedge programs are generally included in interest income on loans and leases on the Consolidated Statements of Income. The tax (benefit) expense amounts reclassified from AOCI in connection with the debt securities AFS and derivative instruments reclassifications are included in income taxes on the Consolidated Statements of Income.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE Basic earnings per common share is calculated by dividing net income available to common stockholders by the weighted average number of shares of common stock outstanding net of unvested shares of restricted stock. Diluted earnings per common share is calculated by dividing net income available to common stockholders by the weighted average number of shares of common stock outstanding, adjusted for the dilutive effect of potential common shares issuable for stock options and restricted shares, as calculated using the treasury stock method. Adjustments to the weighted average number of shares of common stock outstanding are made only when such adjustments dilute earnings per common share. The following table sets forth the computation of basic and diluted earnings per common share: TABLE 15.1 Three Months Ended ( dollars in millions, except per share data) 2021 2020 Net income $ 93 $ 47 Less: Preferred stock dividends 2 2 Net income available to common stockholders $ 91 $ 45 Basic weighted average common shares outstanding 320,975,209 324,247,710 Net effect of dilutive stock options, warrants and restricted stock 3,769,650 1,797,472 Diluted weighted average common shares outstanding 324,744,859 326,045,182 Earnings per common share: Basic $ 0.28 $ 0.14 Diluted $ 0.28 $ 0.14 The following table shows the average shares excluded from the above calculation as their effect would have been anti-dilutive: TABLE 15.2 Three Months Ended 2021 2020 Average shares excluded from the diluted earnings per common share calculation — 450

CASH FLOW INFORMATION

CASH FLOW INFORMATION	3 Months Ended
	Mar. 31, 2021
Supplemental Cash Flow Elements [Abstract]
CASH FLOW INFORMATION	CASH FLOW INFORMATION Following is a summary of supplemental cash flow information: TABLE 16.1 Three Months Ended (in millions) 2021 2020 Interest paid on deposits and other borrowings $ 32 $ 75 Income taxes paid 5 — Transfers of loans to other real estate owned — 1

BUSINESS SEGMENTS

BUSINESS SEGMENTS	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
BUSINESS SEGMENTS	BUSINESS SEGMENTS We operate in three reportable segments: Community Banking, Wealth Management and Insurance. • The Community Banking segment provides commercial and consumer banking services. Commercial banking solutions include corporate banking, small business banking, investment real estate financing, business credit, capital markets and lease financing. Consumer banking products and services include deposit products, mortgage lending, consumer lending and a complete suite of mobile and online banking services. • The Wealth Management segment provides a broad range of personal and corporate fiduciary services including the administration of decedent and trust estates. In addition, it offers various alternative products, including securities brokerage and investment advisory services, mutual funds and annuities. • The Insurance segment includes a full-service insurance brokerage service offering all lines of commercial and personal insurance through major carriers. The Insurance segment also includes a reinsurer. The following tables provide financial information for these segments of FNB. The information provided under the caption “Parent and Other” represents operations not considered to be reportable segments and/or general operating expenses of FNB, and includes the parent company, other non-bank subsidiaries and eliminations and adjustments to reconcile to the Consolidated Financial Statements. TABLE 17.1 (in millions) Community Wealth Insurance Parent and Consolidated At or for the Three Months Ended March 31, 2021 Interest income $ 251 $ — $ — $ — $ 251 Interest expense 25 — — 3 28 Net interest income 226 — — (3) 223 Provision for credit losses 6 — — — 6 Non-interest income 63 15 6 (1) 83 Non-interest expense (1) 165 10 5 2 182 Amortization of intangibles 3 — — — 3 Income tax expense (benefit) 22 1 — (1) 22 Net income (loss) 93 4 1 (5) 93 Total assets 38,360 40 34 41 38,475 Total intangibles 2,276 9 28 — 2,313 At or for the Three Months Ended March 31, 2020 Interest income $ 306 $ — $ — $ — $ 306 Interest expense 68 — — 6 74 Net interest income 238 — — (6) 232 Provision for credit losses 48 — — — 48 Non-interest income 52 13 6 (2) 69 Non-interest expense (1) 176 10 5 1 192 Amortization of intangibles 3 — — — 3 Income tax expense (benefit) 12 1 — (2) 11 Net income (loss) 51 2 1 (7) 47 Total assets 34,933 34 36 46 35,049 Total intangibles 2,288 9 29 — 2,326 (1) Excludes amortization of intangibles, which is presented separately.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Refer to Note 25 "Fair Value Measurements" to the Consolidated Financial Statements included in our 2020 Annual Report on Form 10-K filed with the SEC on February 25, 2021 for a description of additional valuation methodologies for assets and liabilities measured at fair value on a recurring and non-recurring basis. The following table presents the balances of assets and liabilities measured at fair value on a recurring basis: TABLE 18.1 (in millions) Level 1 Level 2 Level 3 Total March 31, 2021 Assets Measured at Fair Value Debt securities available for sale U.S. Treasury $ 100 $ — $ — $ 100 U.S. government agencies — 175 — 175 U.S. government-sponsored entities — 160 — 160 Residential mortgage-backed securities: Agency mortgage-backed securities — 1,103 — 1,103 Agency collateralized mortgage obligations — 1,263 — 1,263 Commercial mortgage-backed securities — 335 — 335 States of the U.S. and political subdivisions (municipals) — 28 — 28 Other debt securities — 2 — 2 Total debt securities available for sale 100 3,066 — 3,166 Loans held for sale — 165 — 165 Derivative financial instruments Trading — 214 — 214 Not for trading — 12 10 22 Total derivative financial instruments — 226 10 236 Total assets measured at fair value on a recurring basis $ 100 $ 3,457 $ 10 $ 3,567 Liabilities Measured at Fair Value Derivative financial instruments Trading $ — $ 58 $ — $ 58 Not for trading — — 1 1 Total derivative financial instruments — 58 1 59 Total liabilities measured at fair value on a recurring basis $ — $ 58 $ 1 $ 59 (in millions) Level 1 Level 2 Level 3 Total December 31, 2020 Assets Measured at Fair Value Debt securities available for sale U.S. Treasury $ 600 $ — $ — $ 600 U.S. government agencies — 172 — 172 U.S. government-sponsored entities — 161 — 161 Residential mortgage-backed securities: Agency mortgage-backed securities — 994 — 994 Agency collateralized mortgage obligations — 1,124 — 1,124 Commercial mortgage-backed securities — 378 — 378 States of the U.S. and political subdivisions (municipals) — 32 — 32 Other debt securities — 2 — 2 Total debt securities available for sale 600 2,863 — 3,463 Loans held for sale — 144 — 144 Derivative financial instruments Trading — 349 — 349 Not for trading — 3 24 27 Total derivative financial instruments — 352 24 376 Total assets measured at fair value on a recurring basis $ 600 $ 3,359 $ 24 $ 3,983 Liabilities Measured at Fair Value Derivative financial instruments Trading $ — $ 37 $ — $ 37 Not for trading — 3 — 3 Total derivative financial instruments — 40 — 40 Total liabilities measured at fair value on a recurring basis $ — $ 40 $ — $ 40 The following table presents additional information about assets measured at fair value on a recurring basis and for which we have utilized Level 3 inputs to determine fair value: TABLE 18.2 (in millions) Interest Total Three Months Ended March 31, 2021 Balance at beginning of period $ 24 $ 24 Purchases, issuances, sales and settlements: Issuances 10 10 Settlements (24) (24) Balance at end of period $ 10 $ 10 Year Ended December 31, 2020 Balance at beginning of period $ 3 $ 3 Purchases, issuances, sales and settlements: Issuances 24 24 Settlements (3) (3) Balance at end of period $ 24 $ 24 We review fair value hierarchy classifications on a quarterly basis. Changes in the observability of the valuation attributes may result in reclassification of certain financial assets or liabilities. Such reclassifications are reported as transfers in/out of Level 3 at fair value at the beginning of the period in which the changes occur. There were no transfers of assets or liabilities between the hierarchy levels during the first three months of 2021 or 2020. From time to time, we measure certain assets at fair value on a non-recurring basis. These adjustments to fair value usually result from the application of the lower of cost or fair value accounting or write-downs of individual assets. Valuation methodologies used to measure these fair value adjustments were described in Note 25, "Fair Value Measurements" to the Consolidated Financial Statements included in 2020 Annual Report on Form 10-K . For assets measured at fair value on a non-recurring basis still held at the Balance Sheet date, the following table provides the hierarchy level and the fair value of the related assets or portfolios: TABLE 18.3 (in millions) Level 1 Level 2 Level 3 Total March 31, 2021 Collateral dependent loans $ — $ — $ 14 $ 14 Other assets - MSRs — — 14 14 Other assets - SBA servicing asset — — 3 3 Other real estate owned — — — — December 31, 2020 Collateral dependent loans $ — $ — $ 45 $ 45 Other assets - MSRs — — 36 36 Other assets - SBA servicing asset — — 3 3 Other real estate owned — — 3 3 The fair value amounts for collateral dependent loans and OREO in the table above were estimated at a date during the three months or twelve months ended March 31, 2021 and December 31, 2020, respectively. Consequently, the fair value information presented is not necessarily as of the period’s end. Collateral dependent loans measured or re-measured at fair value on a non-recurring basis during the three months ended March 31, 2021 had a carrying amount of $19.2 million, which includes an allocated ACL of $18.0 million. The ACL includes a provision applicable to the current period fair value measurements of $6.8 million, which was included in provision for credit losses for the three months ended March 31, 2021. MSRs measured at fair value on a non-recurring basis had a carrying value of $13.9 million, which included a valuation allowance of $4.8 million, as of March 31, 2021. The valuation allowance includes a recovery of $2.5 million included in earnings for the three months ended March 31, 2021. SBA servicing assets measured at fair value on a non-recurring basis had a carrying value of $3.1 million, which included a valuation allowance of $0.9 million, as of March 31, 2021. The valuation allowance includes a recovery of $0.2 million included in earnings for the three months ended March 31, 2021. OREO measured at fair value on a non-recurring basis during 2021 had a carrying amount of $0.5 million and was written down to $0.4 million, resulting in a loss of $0.1 million, which was included in earnings for the three months ended March 31, 2021. Fair Value of Financial Instruments Refer to Note 25, "Fair Value Measurements" to the Consolidated Financial Statements included in our 2020 Annual Report on Form 10-K filed with the SEC on February 25, 2021 for a description of methods and assumptions that were used to estimate the fair value of each financial instrument. The fair values of our financial instruments are as follows: TABLE 18.4 Fair Value Measurements (in millions) Carrying Fair Level 1 Level 2 Level 3 March 31, 2021 Financial Assets Cash and cash equivalents $ 2,668 $ 2,668 $ 2,668 $ — $ — Debt securities available for sale 3,166 3,166 100 3,066 — Debt securities held to maturity 3,043 3,114 1 3,113 — Net loans and leases, including loans held for sale 25,355 24,938 — 165 24,773 Loan servicing rights 42 43 — — 43 Derivative assets 236 236 — 226 10 Accrued interest receivable 89 89 89 — — Financial Liabilities Deposits 30,354 30,376 26,970 3,406 — Short-term borrowings 1,687 1,688 1,688 — — Long-term borrowings 1,091 1,088 — — 1,088 Derivative liabilities 59 59 — 58 1 Accrued interest payable 9 9 9 — — December 31, 2020 Financial Assets Cash and cash equivalents $ 1,383 $ 1,383 $ 1,383 $ — $ — Debt securities available for sale 3,463 3,463 600 2,863 — Debt securities held to maturity 2,868 2,973 — 2,973 — Net loans and leases, including loans held for sale 25,250 25,012 — 144 24,868 Loan servicing rights 39 39 — — 39 Derivative assets 376 376 — 352 24 Accrued interest receivable 90 90 90 — — Financial Liabilities Deposits 29,122 29,158 25,460 3,698 — Short-term borrowings 1,804 1,809 1,809 — — Long-term borrowings 1,095 1,068 — — 1,068 Derivative liabilities 40 40 — 40 — Accrued interest payable 13 13 13 — —

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Our accompanying Consolidated Financial Statements and these Notes to Consolidated Financial Statements (unaudited) include subsidiaries in which we have a controlling financial interest. We own and operate FNBPA, First National Trust Company, First National Investment Services Company, LLC, F.N.B. Investment Advisors, Inc., First National Insurance Agency, LLC, Bank Capital Services, LLC and F.N.B. Capital Corporation, LLC, and include results for each of these entities in the accompanying Consolidated Financial Statements. Companies in which we hold a controlling financial interest, or are a VIE in which we have the power to direct the activities of an entity that most significantly impact the entity’s economic performance and have an obligation to absorb losses or the right to receive benefits which could potentially be significant to the VIE, are consolidated. For a voting interest entity, a controlling financial interest is generally where we hold more than 50% of the outstanding voting shares. VIEs in which we do not hold the power to direct the activities of the entity that most significantly impact the entity’s economic performance or an obligation to absorb losses or the right to receive benefits which could potentially be significant to the VIE are not consolidated. Investments in companies that are not consolidated are accounted for using the equity method when we have the ability to exert significant influence or the cost method when we do not have the ability to exert significant influence. Investments in private investment partnerships that are accounted for under the equity method or the cost method are included in other assets and our proportional interest in the equity investments’ earnings are included in other non-interest income. Investment interests accounted for under the cost and equity methods are periodically evaluated for impairment. The accompanying interim unaudited Consolidated Financial Statements include all adjustments that are necessary, in the opinion of management, to fairly reflect our financial position and results of operations in accordance with GAAP. All significant intercompany balances and transactions have been eliminated. Certain prior period amounts have been reclassified to conform to the current period presentation. Such reclassifications had no impact on our net income and stockholders’ equity. Events occurring subsequent to March 31, 2021 have been evaluated for potential recognition or disclosure in the Consolidated Financial Statements through the date of the filing of the Consolidated Financial Statements with the Securities and Exchange Commission. Certain information and Note disclosures normally included in Consolidated Financial Statements prepared in accordance with GAAP have been condensed or omitted pursuant to the rules and regulations of the SEC. The interim operating results are not necessarily indicative of operating results FNB expects for the full year. These interim unaudited Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and Notes thereto included in our 2020 Annual Report on Form 10-K filed with the SEC on February 25, 2021.
Use of Estimates	Use of Estimates Our accounting and reporting policies conform with GAAP. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying Notes to Consolidated Financial Statements (unaudited). Actual results could materially differ from those estimates. Material estimates that are particularly susceptible to significant changes include the ACL, fair value of financial instruments, goodwill and other intangible assets, income taxes and deferred tax assets and litigation reserves, which are listed in the critical accounting estimates. For a detailed description of our significant accounting policies and critical accounting estimates, see Note 1, "Summary of Significant Accounting Policies" and the "Application of Critical Accounting Policies" section in the MD&A, both in our 2020 Annual Report on Form 10-K .
New Accounting Standards	The following table summarizes accounting pronouncements issued by the FASB that we recently adopted. TABLE 2.1 Standard Description Financial Statements Impact Reference Rate Reform ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ASU 2021-01, Reference Rate Reform (Topic 848): Scope These Updates provide temporary optional expedients and exceptions for applying GAAP to financial contracts, hedging relationships and other transactions affected by RRR if certain criteria are met. The following optional expedients, exceptions and elections are permitted for certain contracts that are modified because of RRR and meet certain scope guidance: • Contract modifications may be accounted for prospectively as a continuation of existing contracts rather than a new contract without remeasurement or reassessment of significant contract amendments • modifications of leases to be accounted for as a continuation of the existing contracts without reassessment of lease classification and discount rate or remeasurement of lease payments • to not reassess the original conclusion about whether a contract contains an embedded derivative that is clearly and closely related to the host contract • changes to critical terms of hedging relationships, on a hedge-by-hedge basis, without designation of the hedging relationship and various practical expedients and elections designed to allow hedge accounting to continue uninterrupted • modifications of certain derivatives modified to change the rate used for margining, discounting or contract price alignment. The Updates also allow an entity to make a one-time election to sell and/or transfer to HTM securities that are affected by RRR and were classified as HTM before January 1, 2020. RRR Updates are effective for all entities from the beginning of an interim period that includes or is subsequent to March 12, 2020 and terminates on December 31, 2022 on a full retrospective or prospective basis. Although we do not expect RRR to have a material accounting impact on our consolidated financial position or results of operations, the Updates will ease the administrative burden in accounting for the effects of RRR. We adopted these updates on October 1, 2020 by retrospective application. The adoption did not have a material impact on our consolidated financial position or results of operations. We will continue to assess the impact of adoption through the termination date of these Updates on December 31, 2022.

NEW ACCOUNTING STANDARDS (Table

NEW ACCOUNTING STANDARDS (Tables)	3 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The following table summarizes accounting pronouncements issued by the FASB that we recently adopted. TABLE 2.1 Standard Description Financial Statements Impact Reference Rate Reform ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ASU 2021-01, Reference Rate Reform (Topic 848): Scope These Updates provide temporary optional expedients and exceptions for applying GAAP to financial contracts, hedging relationships and other transactions affected by RRR if certain criteria are met. The following optional expedients, exceptions and elections are permitted for certain contracts that are modified because of RRR and meet certain scope guidance: • Contract modifications may be accounted for prospectively as a continuation of existing contracts rather than a new contract without remeasurement or reassessment of significant contract amendments • modifications of leases to be accounted for as a continuation of the existing contracts without reassessment of lease classification and discount rate or remeasurement of lease payments • to not reassess the original conclusion about whether a contract contains an embedded derivative that is clearly and closely related to the host contract • changes to critical terms of hedging relationships, on a hedge-by-hedge basis, without designation of the hedging relationship and various practical expedients and elections designed to allow hedge accounting to continue uninterrupted • modifications of certain derivatives modified to change the rate used for margining, discounting or contract price alignment. The Updates also allow an entity to make a one-time election to sell and/or transfer to HTM securities that are affected by RRR and were classified as HTM before January 1, 2020. RRR Updates are effective for all entities from the beginning of an interim period that includes or is subsequent to March 12, 2020 and terminates on December 31, 2022 on a full retrospective or prospective basis. Although we do not expect RRR to have a material accounting impact on our consolidated financial position or results of operations, the Updates will ease the administrative burden in accounting for the effects of RRR. We adopted these updates on October 1, 2020 by retrospective application. The adoption did not have a material impact on our consolidated financial position or results of operations. We will continue to assess the impact of adoption through the termination date of these Updates on December 31, 2022.

SECURITIES (Tables)

SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Schedule of Amortized Cost and Fair Value of Securities Available for Sale	TABLE 3.1 (in millions) Amortized Gross Gross Fair Debt Securities AFS: March 31, 2021 U.S. Treasury $ 100 $ — $ — $ 100 U.S. government agencies 175 — — 175 U.S. government-sponsored entities 160 1 (1) 160 Residential mortgage-backed securities: Agency mortgage-backed securities 1,074 30 (1) 1,103 Agency collateralized mortgage obligations 1,242 26 (5) 1,263 Commercial mortgage-backed securities 328 9 (2) 335 States of the U.S. and political subdivisions (municipals) 29 — (1) 28 Other debt securities 2 — — 2 Total debt securities AFS $ 3,110 $ 66 $ (10) $ 3,166 (in millions) Amortized Gross Gross Fair Debt Securities AFS: December 31, 2020 U.S. Treasury $ 600 $ — $ — $ 600 U.S. government agencies 172 — — 172 U.S. government-sponsored entities 160 1 — 161 Residential mortgage-backed securities: Agency mortgage-backed securities 959 35 — 994 Agency collateralized mortgage obligations 1,094 31 (1) 1,124 Commercial mortgage-backed securities 361 17 — 378 States of the U.S. and political subdivisions (municipals) 32 — — 32 Other debt securities 2 — — 2 Total debt securities AFS $ 3,380 $ 84 $ (1) $ 3,463
Schedule of Amortized Cost and Fair Value of Securities Held to Maturity	TABLE 3.2 (in millions) Amortized Gross Gross Fair Debt Securities HTM: March 31, 2021 U.S. Treasury $ 1 $ — $ — $ 1 U.S. government agencies 1 — — 1 U.S. government-sponsored entities 100 — — 100 Residential mortgage-backed securities: Agency mortgage-backed securities 889 22 (2) 909 Agency collateralized mortgage obligations 643 14 (2) 655 Commercial mortgage-backed securities 314 4 (3) 315 States of the U.S. and political subdivisions (municipals) 1,095 39 (1) 1,133 Total debt securities HTM $ 3,043 $ 79 $ (8) $ 3,114 (in millions) Amortized Gross Gross Fair Debt Securities HTM: December 31, 2020 U.S. Treasury $ 1 $ — $ — $ 1 U.S. government agencies 1 — — 1 U.S. government-sponsored entities 120 1 — 121 Residential mortgage-backed securities: Agency mortgage-backed securities 769 29 — 798 Agency collateralized mortgage obligations 562 17 — 579 Commercial mortgage-backed securities 307 10 — 317 States of the U.S. and political subdivisions (municipals) 1,108 48 — 1,156 Total debt securities HTM $ 2,868 $ 105 $ — $ 2,973
Amortized Cost and Fair Value of Securities, by Contractual Maturities	As of March 31, 2021, the amortized cost and fair value of debt securities, by contractual maturities, were as follows: TABLE 3.3 Available for Sale Held to Maturity (in millions) Amortized Fair Amortized Fair Due in one year or less $ 185 $ 186 $ 100 $ 101 Due after one year but within five years 70 69 21 21 Due after five years but within ten years 127 126 145 147 Due after ten years 84 84 931 966 466 465 1,197 1,235 Residential mortgage-backed securities: Agency mortgage-backed securities 1,074 1,103 889 909 Agency collateralized mortgage obligations 1,242 1,263 643 655 Commercial mortgage-backed securities 328 335 314 315 Total debt securities $ 3,110 $ 3,166 $ 3,043 $ 3,114
Schedule of Securities Pledged as Collateral	Following is information relating to securities pledged: TABLE 3.4 (dollars in millions) March 31, December 31, Securities pledged (carrying value): To secure public deposits, trust deposits and for other purposes as required by law $ 5,429 $ 5,384 As collateral for short-term borrowings 434 402 Securities pledged as a percent of total securities 94.4 % 91.4 %
Summaries of Fair Values and Unrealized Losses of Impaired Securities, Segregated by Length of Impairment	Following are summaries of the fair values of AFS debt securities in an unrealized loss position for which an ACL has not been recorded, segregated by security type and length of continuous loss position: TABLE 3.5 Less than 12 Months 12 Months or More Total (dollars in millions) # Fair Unrealized # Fair Unrealized # Fair Unrealized Debt Securities AFS March 31, 2021 U.S. government agencies 1 $ 1 $ — 16 $ 65 $ — 17 $ 66 $ — U.S. government-sponsored entities 2 74 (1) — — — 2 74 (1) Residential mortgage-backed securities: Agency mortgage-backed securities 2 103 (1) — — — 2 103 (1) Agency collateralized mortgage obligations 10 399 (5) — — — 10 399 (5) Commercial mortgage-backed securities 4 103 (2) — — — 4 103 (2) States of the U.S. and political subdivisions (municipals) 8 22 (1) — — — 8 22 (1) Other debt securities — — — 1 2 — 1 2 — Total 27 $ 702 $ (10) 17 $ 67 $ — 44 $ 769 $ (10) Less than 12 Months 12 Months or More Total (dollars in millions) # Fair Unrealized # Fair Unrealized # Fair Unrealized Debt Securities AFS December 31, 2020 U.S. government agencies 1 $ 13 $ — 16 $ 69 $ — 17 $ 82 $ — U.S. government-sponsored entities 1 25 — — — — 1 25 — Residential mortgage-backed securities: Agency collateralized mortgage obligations 5 130 (1) — — — 5 130 (1) Other debt securities — — — 1 2 — 1 2 — Total 7 $ 168 $ (1) 17 $ 71 $ — 24 $ 239 $ (1)

LOANS AND LEASES (Tables)

LOANS AND LEASES (Tables)	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Summary of Loans and Leases, Net of Unearned Income	Following is a summary of total loans and leases, net of unearned income: TABLE 4.1 (in millions) March 31, 2021 December 31, 2020 Commercial real estate $ 9,799 $ 9,731 Commercial and industrial 7,401 7,214 Commercial leases 471 485 Other 25 40 Total commercial loans and leases 17,696 17,470 Direct installment 2,025 2,020 Residential mortgages 3,329 3,433 Indirect installment 1,201 1,218 Consumer lines of credit 1,281 1,318 Total consumer loans 7,836 7,989 Total loans and leases, net of unearned income $ 25,532 $ 25,459
Certain Information Relating to Commercial Real Estate Loans	The following table shows occupancy information relating to commercial real estate loans: TABLE 4.2 (dollars in millions) March 31, December 31, Commercial real estate: Percent owner-occupied 28.1 % 28.1 % Percent non-owner-occupied 71.9 71.9
Summary of Loan, Credit Quality Indicators	We use an internal risk rating assigned to a commercial loan or lease at origination, summarized below. TABLE 4.3 Rating Category Definition Pass in general, the condition of the borrower and the performance of the loan is satisfactory or better Special Mention in general, the condition of the borrower has deteriorated, requiring an increased level of monitoring Substandard in general, the condition of the borrower has significantly deteriorated and the performance of the loan could further deteriorate if deficiencies are not corrected Doubtful in general, the condition of the borrower has significantly deteriorated and the collection in full of both principal and interest is highly questionable or improbable
Schedule of Financing Receivables, Originated Year	The following tables summarize the designated loan rating category by loan class including term loans on an amortized cost basis by origination year: TABLE 4.4 March 31, 2021 2021 2020 2019 2018 2017 Prior Revolving Loans Amortized Cost Basis Total (in millions) COMMERCIAL Commercial Real Estate: Risk Rating: Pass $ 323 $ 1,876 $ 1,874 $ 1,080 $ 881 $ 2,680 $ 145 $ 8,859 Special Mention 5 12 32 93 151 191 5 489 Substandard — 8 33 41 73 291 5 451 Total commercial real estate 328 1,896 1,939 1,214 1,105 3,162 155 9,799 Commercial and Industrial: Risk Rating: Pass 1,116 2,642 921 561 280 354 1,030 6,904 Special Mention — 32 20 9 28 67 53 209 Substandard 2 8 28 57 45 44 104 288 Total commercial and industrial 1,118 2,682 969 627 353 465 1,187 7,401 Commercial Leases: Risk Rating: Pass 34 158 124 73 52 6 — 447 Special Mention — — 1 3 3 3 — 10 Substandard — 8 3 2 1 — — 14 Total commercial leases 34 166 128 78 56 9 — 471 Other Commercial: Risk Rating: Pass 6 — — — — 4 15 25 Substandard — — — — — — — — Total other commercial 6 — — — — 4 15 25 Total commercial 1,486 4,744 3,036 1,919 1,514 3,640 1,357 17,696 CONSUMER Direct Installment: Current 154 676 306 182 130 560 — 2,008 Past due — — 1 1 1 14 — 17 Total direct installment 154 676 307 183 131 574 — 2,025 Residential Mortgages: Current 248 1,033 586 239 327 856 1 3,290 Past due — 1 2 3 4 29 — 39 Total residential mortgages 248 1,034 588 242 331 885 1 3,329 Indirect Installment: Current 122 353 233 289 123 75 — 1,195 Past due — 1 2 1 1 1 — 6 Total indirect installment 122 354 235 290 124 76 — 1,201 Consumer Lines of Credit: Current 1 4 5 8 3 132 1,114 1,267 Past due — — — — — 13 1 14 Total consumer lines of credit 1 4 5 8 3 145 1,115 1,281 Total consumer 525 2,068 1,135 723 589 1,680 1,116 7,836 Total loans and leases $ 2,011 $ 6,812 $ 4,171 $ 2,642 $ 2,103 $ 5,320 $ 2,473 $ 25,532 December 31, 2020 2020 2019 2018 2017 2016 Prior Revolving Loans Amortized Cost Basis Total (in millions) COMMERCIAL Commercial Real Estate: Risk Rating: Pass $ 1,879 $ 1,854 $ 1,135 $ 927 $ 888 $ 1,911 $ 163 $ 8,757 Special Mention 9 30 80 158 70 163 4 514 Substandard 4 32 29 81 116 192 6 460 Total commercial real estate 1,892 1,916 1,244 1,166 1,074 2,266 173 9,731 Commercial and Industrial: Risk Rating: Pass 3,286 1,007 590 304 120 311 1,095 6,713 Special Mention 30 23 13 28 10 35 79 218 Substandard 8 26 65 44 6 37 97 283 Total commercial and industrial 3,324 1,056 668 376 136 383 1,271 7,214 Commercial Leases: Risk Rating: Pass 178 134 83 56 5 3 — 459 Special Mention 1 1 4 4 1 2 — 13 Substandard 7 2 2 1 1 — — 13 Total commercial leases 186 137 89 61 7 5 — 485 Other Commercial: Risk Rating: Pass — — — — — 4 35 39 Substandard — — — — — 1 — 1 Total other commercial — — — — — 5 35 40 Total commercial 5,402 3,109 2,001 1,603 1,217 2,659 1,479 17,470 CONSUMER Direct Installment: Current 706 337 200 143 171 442 1 2,000 Past due — 1 2 1 2 14 — 20 Total direct installment 706 338 202 144 173 456 1 2,020 Residential Mortgages: Current 1,079 707 283 378 330 603 1 3,381 Past due 1 5 7 4 6 29 — 52 Total residential mortgages 1,080 712 290 382 336 632 1 3,433 Indirect Installment: Current 372 260 332 147 67 27 — 1,205 Past due 1 3 4 2 2 1 — 13 Total indirect installment 373 263 336 149 69 28 — 1,218 Consumer Lines of Credit: Current 4 7 8 3 5 127 1,146 1,300 Past due — — — — — 15 3 18 Total consumer lines of credit 4 7 8 3 5 142 1,149 1,318 Total consumer 2,163 1,320 836 678 583 1,258 1,151 7,989 Total loans and leases $ 7,565 $ 4,429 $ 2,837 $ 2,281 $ 1,800 $ 3,917 $ 2,630 $ 25,459
Age Analysis of Past Due Loans, by Class	The following tables provide an analysis of the aging of loans by class. TABLE 4.5 (in millions) 30-89 Days > 90 Days Past Due and Still Accruing Non- Total Current Total Non-accrual with No ACL March 31, 2021 Commercial real estate $ 8 $ — $ 78 $ 86 $ 9,713 $ 9,799 $ 30 Commercial and industrial 2 — 36 38 7,363 7,401 15 Commercial leases 3 — 2 5 466 471 — Other — — — — 25 25 — Total commercial loans and leases 13 — 116 129 17,567 17,696 45 Direct installment 5 1 11 17 2,008 2,025 — Residential mortgages 12 6 21 39 3,290 3,329 — Indirect installment 4 — 2 6 1,195 1,201 — Consumer lines of credit 4 3 7 14 1,267 1,281 — Total consumer loans 25 10 41 76 7,760 7,836 — Total loans and leases $ 38 $ 10 $ 157 $ 205 $ 25,327 $ 25,532 $ 45 (in millions) 30-89 Days > 90 Days Past Due and Still Accruing Non- Total Current Total Non-accrual with No ACL December 31, 2020 Commercial real estate $ 13 $ — $ 85 $ 98 $ 9,633 $ 9,731 $ 36 Commercial and industrial 8 — 44 52 7,162 7,214 16 Commercial leases 2 — 2 4 481 485 — Other — — 1 1 39 40 — Total commercial loans and leases 23 — 132 155 17,315 17,470 52 Direct installment 7 2 11 20 2,000 2,020 — Residential mortgages 23 11 18 52 3,381 3,433 — Indirect installment 10 1 2 13 1,205 1,218 — Consumer lines of credit 9 2 7 18 1,300 1,318 — Total consumer loans 49 16 38 103 7,886 7,989 — Total loans and leases $ 72 $ 16 $ 170 $ 258 $ 25,201 $ 25,459 $ 52
Summary of Non-Performing Assets	Following is a summary of non-performing assets: TABLE 4.6 (dollars in millions) March 31, December 31, Non-accrual loans $ 157 $ 170 Total non-performing loans 157 170 Other real estate owned 9 10 Total non-performing assets $ 166 $ 180 Asset quality ratios: Non-performing loans / total loans and leases 0.62 % 0.67 % Non-performing assets + 90 days past due + OREO / total loans and leases + OREO 0.68 0.77
Summary of the composition of total TDRs	Following is a summary of the composition of total TDRs: TABLE 4.7 (in millions) March 31, December 31, Accruing $ 58 $ 58 Non-accrual 40 33 Total TDRs $ 98 $ 91
Summary of Troubled Debt Restructurings by Class of Loans	Following is a summary of TDR loans, by class, for loans that were modified during the periods indicated: TABLE 4.8 Three Months Ended March 31, 2021 (dollars in millions) Number Pre- Post- Commercial real estate 11 $ 17 $ 17 Commercial and industrial 1 — — Total commercial loans 12 17 17 Direct installment 10 — — Residential mortgages 2 1 1 Consumer lines of credit 10 1 1 Total consumer loans 22 2 2 Total 34 $ 19 $ 19 Three Months Ended March 31, 2020 (dollars in millions) Number Pre- Post- Commercial real estate 5 $ 1 $ 1 Commercial and industrial 7 1 — Total commercial loans 12 2 1 Direct installment 19 2 2 Residential mortgages 14 1 1 Consumer lines of credit 15 — — Total consumer loans 48 3 3 Total 60 $ 5 $ 4 The year-to-date items in the above tables have been adjusted for loans that have been paid off and/or sold.
Summary of Troubled Debt Restructurings by Class of Loans and Leases, Payment Default	Following is a summary of TDRs, by class, for which there was a payment default, excluding loans that have been paid off and/or sold. Default occurs when a loan is 90 days or more past due and is within 12 months of restructuring. TABLE 4.9 Three Months Ended (dollars in millions) Number of Recorded Commercial and industrial 1 $ — Total commercial loans 1 — Residential mortgages 1 — Total consumer loans 1 — Total 2 $ — Three Months Ended (dollars in millions) Number of Recorded Commercial real estate 10 $ 4 Commercial and industrial 2 — Total commercial loans 12 4 Direct installment 4 — Residential mortgages 1 — Total consumer loans 5 — Total 17 $ 4

ALLOWANCE FOR CREDIT LOSSES O_2

ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES (Tables)	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Summary of Changes in Allowance for Credit Losses by Loan and Lease Class	Following is a summary of changes in the ACL, by loan and lease class: TABLE 5.1 (in millions) Balance at Charge- Recoveries Net Provision for Credit Losses Balance at Three Months Ended March 31, 2021 Commercial real estate $ 181 $ (1) $ 1 $ — $ 3 $ 184 Commercial and industrial 81 (8) 1 (7) 5 79 Commercial leases 17 — 1 1 (1) 17 Other 1 (1) 1 — — 1 Total commercial loans and leases 280 (10) 4 (6) 7 281 Direct installment 26 — — — — 26 Residential mortgages 34 — — — (2) 32 Indirect installment 11 (2) 1 (1) 1 11 Consumer lines of credit 12 — — — — 12 Total consumer loans 83 (2) 1 (1) (1) 81 Total allowance for credit losses on loans and leases 363 (12) 5 (7) 6 362 Allowance for unfunded loan commitments 14 — — — — 14 Total allowance for credit losses on loans and leases and allowance for unfunded loan commitments $ 377 $ (12) $ 5 $ (7) $ 6 $ 376 (in millions) Balance at Charge- Recoveries Net Provision ASC 326 Adoption Impact Initial ACL on PCD Loans Balance at Three Months Ended March 31, 2020 Commercial real estate $ 60 $ (2) $ 4 $ 2 $ 12 $ 38 $ 40 $ 152 Commercial and industrial 53 (4) 1 (3) 26 8 4 88 Commercial leases 11 — — — 2 — — 13 Other 9 (1) — (1) 2 (9) — 1 Total commercial loans and leases 133 (7) 5 (2) 42 37 44 254 Direct installment 13 (1) — (1) 3 10 1 26 Residential mortgages 22 — — — (1) 6 4 31 Indirect installment 19 (3) 1 (2) 2 2 — 21 Consumer lines of credit 9 (1) — (1) 2 — 1 11 Total consumer loans 63 (5) 1 (4) 6 18 6 89 Total allowance for credit losses on loans and leases 196 (12) 6 (6) 48 55 50 343 Allowance for unfunded loan commitments (1) 3 — — — 1 10 — 14 Total allowance for credit losses on loans and leases and allowance for unfunded loan commitments $ 199 $ (12) $ 6 $ (6) $ 49 $ 65 $ 50 $ 357 (1) The $1 million provision for the AULC is included in other non-interest expense on the Consolidated Statements of Income. Following is a summary of changes in the AULC by portfolio segment: TABLE 5.2 Three Months Ended 2021 2020 (in millions) Balance at beginning of period $ 14 $ 3 Provision for unfunded loan commitments and letters of credit: Commercial portfolio — — Consumer portfolio — — Other adjustments: Commercial portfolio — 1 ASC 326 adoption impact: Commercial portfolio — 8 Consumer portfolio — 2 Balance at end of period $ 14 $ 14

LOAN SERVICING (Tables)

LOAN SERVICING (Tables) - Mortgage Servicing Rights [Member]	3 Months Ended
	Mar. 31, 2021
Servicing Assets at Fair Value [Line Items]
Servicing Asset at Amortized Cost	The unpaid principal balance of mortgage loans serviced for others is listed below: TABLE 6.1 (in millions) March 31, December 31, Mortgage loans sold with servicing retained $ 4,670 $ 4,653 The following table summarizes activity relating to mortgage loans sold with servicing retained: TABLE 6.2 Three Months Ended (in millions) 2021 2020 Mortgage loans sold with servicing retained $ 506 $ 260 Pretax net gains resulting from above loan sales (1) 17 7 Mortgage servicing fees (1) 3 3 (1) Recorded in mortgage banking operations on the Consolidated Statements of Income. Following is a summary of activity relating to MSRs: TABLE 6.3 Three Months Ended (in millions) 2021 2020 Balance at beginning of period $ 35.6 $ 42.6 Additions 5.2 2.5 Payoffs and curtailments (4.1) (1.9) (Impairment charge) / recovery 2.5 (7.7) Amortization (0.6) (0.6) Balance at end of period $ 38.6 $ 34.9 Fair value, beginning of period $ 35.6 $ 45.0 Fair value, end of period 40.2 34.9
Schedule of Assumptions for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement	Following is a summary of the sensitivity of the fair value of MSRs to changes in key assumptions: TABLE 6.4 (dollars in millions) March 31, December 31, Weighted average life (months) 71.3 66.6 Constant prepayment rate (annualized) 12.6 % 13.4 % Discount rate 9.5 % 9.5 % Effect on fair value due to change in interest rates: +0.25% $ 3 $ 2 +0.50% 5 4 -0.25% (3) (2) -0.50% (6) (3)

OPERATING LEASES (Tables)

OPERATING LEASES (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Lease, Cost	The components of lease expense were as follows: TABLE 7.1 Three Months Ended (dollars in millions) 2021 2020 Operating lease cost $ 7 $ 7 Variable lease cost 1 1 Total lease cost $ 8 $ 8
Leases, Other Information	Other information related to leases is as follows: TABLE 7.2 Three Months Ended (dollars in millions) 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 7 $ 6 Right-of-use assets obtained in exchange for lease obligations: Operating leases — 4 Weighted average remaining lease term (years): Operating leases 9.39 9.64 Weighted average discount rate: Operating leases 2.6 % 2.9 %
Lessor, Operating Lease, Payments to be Received, Maturity	Maturities of operating lease liabilities were as follows: TABLE 7.3 (in millions) March 31, 2021 $ 19 2022 22 2023 17 2024 16 2025 12 Later years 64 Total lease payments 150 Less: imputed interest (20) Present value of lease liabilities $ 130

VARIABLE INTEREST ENTITIES (Tab

VARIABLE INTEREST ENTITIES (Tables)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities, Assets and Liabilities	The following table provides a summary of the assets and liabilities included in our Consolidated Financial Statements, as well as the maximum exposure to losses, associated with our interests related to VIEs for which we hold an interest, but are not the primary beneficiary, at March 31, 2021 and December 31, 2020. TABLE 8.1 (in millions) Total Assets Total Liabilities Maximum Exposure to Loss March 31, 2021 Trust preferred securities (1) $ 1 $ 66 $ — Affordable housing tax credit partnerships 115 41 115 Other investments 26 7 26 Total $ 142 $ 114 $ 141 December 31, 2020 Trust preferred securities (1) $ 1 $ 66 $ — Affordable housing tax credit partnerships 119 45 119 Other investments 26 8 26 Total $ 146 $ 119 $ 145 (1) Represents our investment in unconsolidated subsidiaries.
Low Income Housing Tax Credits, Balances Of Affordable Housing Tax Credit Investments And Related Unfunded Commitments	The following table presents the balances of our affordable housing tax credit investments and related unfunded commitments: TABLE 8.2 (in millions) March 31, December 31, Proportional amortization method investments included in other assets $ 71 $ 71 Equity method investments included in other assets 3 3 Total LIHTC investments included in other assets $ 74 $ 74 Unfunded LIHTC commitments $ 41 $ 45
Low Income Housing Tax Credits, Income Statement Effect	The following table summarizes the impact of these LIHTC investments on specific line items of our Consolidated Statements of Income: TABLE 8.3 Three Months Ended (in millions) 2021 2020 Non-interest income: Amortization of tax credit investments under equity method, net of tax benefit $ — $ — Provision for income taxes: Amortization of LIHTC investments under proportional method $ 3 $ 3 Low-income housing tax credits (3) (3) Other tax benefits related to tax credit investments (1) (1) Total provision for income taxes $ (1) $ (1)

BORROWINGS (Tables)

BORROWINGS (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Summary of Short-Term Borrowings	Following is a summary of short-term borrowings: TABLE 9.1 (in millions) March 31, December 31, Securities sold under repurchase agreements $ 435 $ 403 Federal Home Loan Bank advances 1,130 1,280 Subordinated notes 122 121 Total short-term borrowings $ 1,687 $ 1,804
Summary of Long-Term Borrowings	Following is a summary of long-term borrowings: TABLE 9.2 (in millions) March 31, December 31, Federal Home Loan Bank advances $ 400 $ 400 Senior notes 299 299 Subordinated notes 78 81 Junior subordinated debt 66 66 Other subordinated debt 248 249 Total long-term borrowings $ 1,091 $ 1,095
Schedule of Other Subordinated Debt	The subordinated notes are eligible for treatment as tier 2 capital for regulatory capital purposes. TABLE 9.3 (dollars in millions) Aggregate Principal Amount Issued Net Proceeds (2) Carrying Value Stated Maturity Date Interest 2.20% Senior Notes due February 24, 2023 $ 300 $ 298 $ 299 2/24/2023 2.20 % 4.95% Fixed-To-Floating Rate Subordinated Notes due 2029 120 118 118 2/14/2029 4.95 % 4.875% Subordinated Notes due 2025 100 98 99 10/2/2025 4.875 % 7.625% Subordinated Notes due August 12, 2023 (1) 38 46 31 8/12/2023 7.625 % Total $ 558 $ 560 $ 547 (1) Assumed from a prior acquisition and adjusted to fair value at the time of acquisition. (2) After deducting underwriting discounts and commissions and offering costs. For the debt assumed from a prior acquisition, this is the fair value of the debt at the time of the acquisition.
Schedule of Junior Subordinated Debt Trusts	The following table provides information relating to the Trusts as of March 31, 2021: TABLE 9.4 (dollars in millions) Trust Common Junior Stated Interest Rate Rate Reset Factor F.N.B. Statutory Trust II $ 22 $ 1 $ 22 6/15/2036 1.83 % LIBOR + 165 basis points (bps) Yadkin Valley Statutory Trust I 25 1 22 12/15/2037 1.50 % LIBOR + 132 bps FNB Financial Services Capital Trust I 25 1 22 9/30/2035 1.66 % LIBOR + 146 bps Total $ 72 $ 3 $ 66

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Notional Amounts and Gross Fair Values of Derivative Assets and Derivative Liabilities	The following table presents notional amounts and gross fair values of our derivative assets and derivative liabilities which are not offset in the Consolidated Balance Sheets: TABLE 10.1 March 31, 2021 December 31, 2020 Notional Fair Value Notional Fair Value (in millions) Amount Asset Liability Amount Asset Liability Gross Derivatives Subject to master netting arrangements: Interest rate contracts – designated $ 1,180 $ 2 $ — $ 1,430 $ 3 $ — Interest rate swaps – not designated 4,947 4 25 4,791 — 37 Total subject to master netting arrangements 6,127 6 25 6,221 3 37 Not subject to master netting arrangements: Interest rate swaps – not designated 4,947 211 32 4,791 349 — Interest rate lock commitments – not designated 549 10 1 531 24 — Forward delivery commitments – not designated 571 9 — 500 — 2 Credit risk contracts – not designated 425 — 1 437 — 1 Total not subject to master netting arrangements 6,492 230 34 6,259 373 3 Total $ 12,619 $ 236 $ 59 $ 12,480 $ 376 $ 40
Summary of Amounts Reclassified from Accumulated Other Comprehensive Income (AOCI)	The following table shows amounts reclassified from AOCI: TABLE 10.2 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from AOCI into Income Amount of Gain (Loss) Reclassified from AOCI into Income Three Months Ended Three Months Ended (in millions) 2021 2020 2021 2020 Derivatives in cash flow hedging relationships: Interest rate contracts $ 5 $ (45) Interest income (expense) $ (5) $ (1)
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table represents gains (losses) recognized in the Consolidated Statements of Income on cash flow hedging relationships: TABLE 10.3 Three months ended March 31, 2021 2020 (in millions) Interest Income - Loans and Leases Interest Expense - Short-Term Borrowings Interest Income - Loans and Leases Interest Expense - Short-Term Borrowings Total amounts of income and expense line items presented in the Consolidated Statements of Income (the effects of cash flow hedges are included in these line items) $ 221 $ 7 $ 266 $ 14 The effects of cash flow hedging: Gain (loss) on cash flow hedging relationships: Interest rate contracts: Amount of gain (loss) reclassified from AOCI into net income — (5) — (1)
Schedule of Derivative Financial Instruments on the Consolidated Statements of Income	The following table presents the effect of certain derivative financial instruments on the Consolidated Statements of Income: TABLE 10.4 Three Months Ended (in millions) Consolidated Statements of Income Location 2021 2020 Interest rate swaps Non-interest income - other $ — $ — Interest rate lock commitments Mortgage banking operations — — Forward delivery contracts Mortgage banking operations 9 (1) Credit risk contracts Non-interest income - other — —
Schedule of Offsetting Assets and Liabilities	The following table presents a reconciliation of the net amounts of derivative assets and derivative liabilities presented in the Consolidated Balance Sheets to the net amounts that would result in the event of offset: TABLE 10.5 Amount Not Offset in the (in millions) Net Amount Financial Cash Net March 31, 2021 Derivative Assets Interest rate contracts: Designated $ 2 $ — $ 2 $ — Not designated 4 — 4 — Total $ 6 $ — $ 6 $ — Derivative Liabilities Interest rate contracts: Not designated $ 25 $ — $ 25 $ — Total $ 25 $ — $ 25 $ — December 31, 2020 Derivative Assets Interest rate contracts: Designated $ 3 $ — $ 3 $ — Total $ 3 $ — $ 3 $ — Derivative Liabilities Interest rate contracts: Not designated $ 37 $ — $ 37 $ — Total $ 37 $ — $ 37 $ —

COMMITMENTS, CREDIT RISK AND _2

COMMITMENTS, CREDIT RISK AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of Off-Balance Sheet Credit Risk Information	Following is a summary of off-balance sheet credit risk information: TABLE 11.1 (in millions) March 31, December 31, Commitments to extend credit $ 9,806 $ 9,285 Standby letters of credit 168 158

STOCK INCENTIVE PLANS (Tables)

STOCK INCENTIVE PLANS (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Activity Relating to Restricted Stock Units	The following table summarizes the activity relating to restricted stock units during the periods indicated: TABLE 12.1 Three Months Ended March 31, 2021 2020 Units Weighted Units Weighted Unvested units outstanding at beginning of period 4,322,115 $ 9.46 2,858,357 $ 12.56 Granted 542,136 12.61 1,988,225 6.95 Net adjustment due to performance 327,256 11.84 — — Vested (142,687) 7.29 (1,717) 14.15 Forfeited/expired (8,334) 7.52 (11,362) 12.85 Dividend reinvestment 42,310 13.43 39,865 8.57 Unvested units outstanding at end of period 5,082,796 10.05 4,873,368 10.23
Schedule of Certain Information Related to Restricted Stock Units	The following table provides certain information related to restricted stock units: TABLE 12.2 (in millions) Three Months Ended 2021 2020 Stock-based compensation expense $ 12 $ 8 Tax benefit related to stock-based compensation expense 3 2 Fair value of units vested 1 —
Components of Restricted Stock Units	The components of the restricted stock units as of March 31, 2021 are as follows: TABLE 12.3 (dollars in millions) Service- Performance- Total Unvested restricted stock units 3,076,326 2,006,470 5,082,796 Unrecognized compensation expense $ 7 $ 3 $ 10 Intrinsic value $ 39 $ 25 $ 64 Weighted average remaining life (in years) 1.64 1.27 1.49

INCOME TAXES (Tables)

INCOME TAXES (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Federal and state income tax expense and the statutory tax rate and the actual effective tax rate consist of the following: TABLE 13.1 Three Months Ended (in millions) 2021 2020 Current income taxes: Federal taxes $ 21 $ 7 State taxes 2 2 Total current income taxes 23 9 Deferred income taxes: Federal taxes (1) 2 State taxes — — Total deferred income taxes (1) 2 Total income taxes $ 22 $ 11 Statutory tax rate 21.0 % 21.0 % Effective tax rate 18.9 % 18.8 %

OTHER COMPREHENSIVE INCOME (Tab

OTHER COMPREHENSIVE INCOME (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Changes in AOCI, Net of Tax, by Component	The following table presents changes in AOCI, net of tax, by component: TABLE 14.1 (in millions) Unrealized Unrealized Unrecognized Total Three Months Ended March 31, 2021 Balance at beginning of period $ 65 $ (40) $ (64) $ (39) Other comprehensive (loss) income before reclassifications (21) 4 1 (16) Amounts reclassified from AOCI — 4 — 4 Net current period other comprehensive (loss) income (21) 8 1 (12) Balance at end of period $ 44 $ (32) $ (63) $ (51)

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Common Share	The following table sets forth the computation of basic and diluted earnings per common share: TABLE 15.1 Three Months Ended ( dollars in millions, except per share data) 2021 2020 Net income $ 93 $ 47 Less: Preferred stock dividends 2 2 Net income available to common stockholders $ 91 $ 45 Basic weighted average common shares outstanding 320,975,209 324,247,710 Net effect of dilutive stock options, warrants and restricted stock 3,769,650 1,797,472 Diluted weighted average common shares outstanding 324,744,859 326,045,182 Earnings per common share: Basic $ 0.28 $ 0.14 Diluted $ 0.28 $ 0.14
Schedule of Average Shares Excluded from Diluted Earnings Per Common Share Calculation	The following table shows the average shares excluded from the above calculation as their effect would have been anti-dilutive: TABLE 15.2 Three Months Ended 2021 2020 Average shares excluded from the diluted earnings per common share calculation — 450

CASH FLOW INFORMATION (Tables)

CASH FLOW INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2021
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information	Following is a summary of supplemental cash flow information: TABLE 16.1 Three Months Ended (in millions) 2021 2020 Interest paid on deposits and other borrowings $ 32 $ 75 Income taxes paid 5 — Transfers of loans to other real estate owned — 1

BUSINESS SEGMENTS (Tables)

BUSINESS SEGMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Financial Information for Segments of FNB	The following tables provide financial information for these segments of FNB. The information provided under the caption “Parent and Other” represents operations not considered to be reportable segments and/or general operating expenses of FNB, and includes the parent company, other non-bank subsidiaries and eliminations and adjustments to reconcile to the Consolidated Financial Statements. TABLE 17.1 (in millions) Community Wealth Insurance Parent and Consolidated At or for the Three Months Ended March 31, 2021 Interest income $ 251 $ — $ — $ — $ 251 Interest expense 25 — — 3 28 Net interest income 226 — — (3) 223 Provision for credit losses 6 — — — 6 Non-interest income 63 15 6 (1) 83 Non-interest expense (1) 165 10 5 2 182 Amortization of intangibles 3 — — — 3 Income tax expense (benefit) 22 1 — (1) 22 Net income (loss) 93 4 1 (5) 93 Total assets 38,360 40 34 41 38,475 Total intangibles 2,276 9 28 — 2,313 At or for the Three Months Ended March 31, 2020 Interest income $ 306 $ — $ — $ — $ 306 Interest expense 68 — — 6 74 Net interest income 238 — — (6) 232 Provision for credit losses 48 — — — 48 Non-interest income 52 13 6 (2) 69 Non-interest expense (1) 176 10 5 1 192 Amortization of intangibles 3 — — — 3 Income tax expense (benefit) 12 1 — (2) 11 Net income (loss) 51 2 1 (7) 47 Total assets 34,933 34 36 46 35,049 Total intangibles 2,288 9 29 — 2,326 (1) Excludes amortization of intangibles, which is presented separately.

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Balances of Assets and Liabilities Measured at Fair Value on Recurring Basis	The following table presents the balances of assets and liabilities measured at fair value on a recurring basis: TABLE 18.1 (in millions) Level 1 Level 2 Level 3 Total March 31, 2021 Assets Measured at Fair Value Debt securities available for sale U.S. Treasury $ 100 $ — $ — $ 100 U.S. government agencies — 175 — 175 U.S. government-sponsored entities — 160 — 160 Residential mortgage-backed securities: Agency mortgage-backed securities — 1,103 — 1,103 Agency collateralized mortgage obligations — 1,263 — 1,263 Commercial mortgage-backed securities — 335 — 335 States of the U.S. and political subdivisions (municipals) — 28 — 28 Other debt securities — 2 — 2 Total debt securities available for sale 100 3,066 — 3,166 Loans held for sale — 165 — 165 Derivative financial instruments Trading — 214 — 214 Not for trading — 12 10 22 Total derivative financial instruments — 226 10 236 Total assets measured at fair value on a recurring basis $ 100 $ 3,457 $ 10 $ 3,567 Liabilities Measured at Fair Value Derivative financial instruments Trading $ — $ 58 $ — $ 58 Not for trading — — 1 1 Total derivative financial instruments — 58 1 59 Total liabilities measured at fair value on a recurring basis $ — $ 58 $ 1 $ 59 (in millions) Level 1 Level 2 Level 3 Total December 31, 2020 Assets Measured at Fair Value Debt securities available for sale U.S. Treasury $ 600 $ — $ — $ 600 U.S. government agencies — 172 — 172 U.S. government-sponsored entities — 161 — 161 Residential mortgage-backed securities: Agency mortgage-backed securities — 994 — 994 Agency collateralized mortgage obligations — 1,124 — 1,124 Commercial mortgage-backed securities — 378 — 378 States of the U.S. and political subdivisions (municipals) — 32 — 32 Other debt securities — 2 — 2 Total debt securities available for sale 600 2,863 — 3,463 Loans held for sale — 144 — 144 Derivative financial instruments Trading — 349 — 349 Not for trading — 3 24 27 Total derivative financial instruments — 352 24 376 Total assets measured at fair value on a recurring basis $ 600 $ 3,359 $ 24 $ 3,983 Liabilities Measured at Fair Value Derivative financial instruments Trading $ — $ 37 $ — $ 37 Not for trading — 3 — 3 Total derivative financial instruments — 40 — 40 Total liabilities measured at fair value on a recurring basis $ — $ 40 $ — $ 40
Additional Information about Assets Measured at Fair Value on Recurring Basis	The following table presents additional information about assets measured at fair value on a recurring basis and for which we have utilized Level 3 inputs to determine fair value: TABLE 18.2 (in millions) Interest Total Three Months Ended March 31, 2021 Balance at beginning of period $ 24 $ 24 Purchases, issuances, sales and settlements: Issuances 10 10 Settlements (24) (24) Balance at end of period $ 10 $ 10 Year Ended December 31, 2020 Balance at beginning of period $ 3 $ 3 Purchases, issuances, sales and settlements: Issuances 24 24 Settlements (3) (3) Balance at end of period $ 24 $ 24
Additional Information about Assets Measured at Fair Value on Non-Recurring Basis	For assets measured at fair value on a non-recurring basis still held at the Balance Sheet date, the following table provides the hierarchy level and the fair value of the related assets or portfolios: TABLE 18.3 (in millions) Level 1 Level 2 Level 3 Total March 31, 2021 Collateral dependent loans $ — $ — $ 14 $ 14 Other assets - MSRs — — 14 14 Other assets - SBA servicing asset — — 3 3 Other real estate owned — — — — December 31, 2020 Collateral dependent loans $ — $ — $ 45 $ 45 Other assets - MSRs — — 36 36 Other assets - SBA servicing asset — — 3 3 Other real estate owned — — 3 3
Fair Values of Financial Instruments	The fair values of our financial instruments are as follows: TABLE 18.4 Fair Value Measurements (in millions) Carrying Fair Level 1 Level 2 Level 3 March 31, 2021 Financial Assets Cash and cash equivalents $ 2,668 $ 2,668 $ 2,668 $ — $ — Debt securities available for sale 3,166 3,166 100 3,066 — Debt securities held to maturity 3,043 3,114 1 3,113 — Net loans and leases, including loans held for sale 25,355 24,938 — 165 24,773 Loan servicing rights 42 43 — — 43 Derivative assets 236 236 — 226 10 Accrued interest receivable 89 89 89 — — Financial Liabilities Deposits 30,354 30,376 26,970 3,406 — Short-term borrowings 1,687 1,688 1,688 — — Long-term borrowings 1,091 1,088 — — 1,088 Derivative liabilities 59 59 — 58 1 Accrued interest payable 9 9 9 — — December 31, 2020 Financial Assets Cash and cash equivalents $ 1,383 $ 1,383 $ 1,383 $ — $ — Debt securities available for sale 3,463 3,463 600 2,863 — Debt securities held to maturity 2,868 2,973 — 2,973 — Net loans and leases, including loans held for sale 25,250 25,012 — 144 24,868 Loan servicing rights 39 39 — — 39 Derivative assets 376 376 — 352 24 Accrued interest receivable 90 90 90 — — Financial Liabilities Deposits 29,122 29,158 25,460 3,698 — Short-term borrowings 1,804 1,809 1,809 — — Long-term borrowings 1,095 1,068 — — 1,068 Derivative liabilities 40 40 — 40 — Accrued interest payable 13 13 13 — —

NATURE OF OPERATIONS (Detail)

NATURE OF OPERATIONS (Detail)	3 Months Ended
	Mar. 31, 2021StateOffice
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of states, company operating financial services | State	7
Number of banking offices | Office	337

SECURITIES - Additional Informa

SECURITIES - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Securities [Line Items]
Debt securities available for sale, allowance for credit losses	$ 0	$ 0
Debt securities held to maturity, allowance for credit losses	40,000	40,000
Municipal bond portfolio, value	$ 1,100,000,000
Percentage of formal credit enhancement insurance of municipalities	62.00%
Municipal Bonds [Member] | Weighted Average [Member]
Schedule Of Securities [Line Items]
Average holding size of securities in bond portfolio	$ 3,600,000
Municipal Bonds [Member] | Credit Concentration Risk [Member] | General Obligation Bonds [Member] | A Rating or Better [Member] | Minimum [Member]
Schedule Of Securities [Line Items]
Percentage of portfolio	99.00%
Municipal Bonds [Member] | Geographic Concentration Risk [Member] | Pennsylvania, Ohio and Maryland [Member]
Schedule Of Securities [Line Items]
Percentage of portfolio	65.00%
Available-for-sale Debt Securities [Member]
Schedule Of Securities [Line Items]
Accrued investment income receivable	$ 5,900,000	6,200,000
Municipal Portfolio [Member]
Schedule Of Securities [Line Items]
Debt securities held to maturity, allowance for credit losses	40,000	40,000
Held-to-maturity Securities [Member]
Schedule Of Securities [Line Items]
Accrued investment income receivable	$ 11,500,000	$ 12,500,000

SECURITIES - Amortized Cost and

SECURITIES - Amortized Cost and Fair Value of Securities Available for Sale (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 3,110	$ 3,380
Gross Unrealized Gains	66	84
Gross Unrealized Losses	(10)	(1)
Fair Value	3,166	3,463
U.S. Treasury [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	100	600
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	100	600
US Government Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	175	172
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	175	172
U.S. Government-Sponsored Entities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	160	160
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(1)	0
Fair Value	160	161
Agency Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,074	959
Gross Unrealized Gains	30	35
Gross Unrealized Losses	(1)	0
Fair Value	1,103	994
Agency Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,242	1,094
Gross Unrealized Gains	26	31
Gross Unrealized Losses	(5)	(1)
Fair Value	1,263	1,124
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	328	361
Gross Unrealized Gains	9	17
Gross Unrealized Losses	(2)	0
Fair Value	335	378
States of the U.S. and Political Subdivisions (municipals) [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	29	32
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	0
Fair Value	28	32
Other Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2	2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 2	$ 2

SECURITIES - Amortized Cost a_2

SECURITIES - Amortized Cost and Fair Value of Securities Held to Maturity (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Investment Securities Held To Maturity [Line Items]
Amortized Cost	$ 3,043	$ 2,868
Gross Unrealized Gains	79	105
Gross Unrealized Losses	(8)	0
Fair  Value	3,114	2,973
U.S. Treasury [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	1	1
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair  Value	1	1
US Government Agencies [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	1	1
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair  Value	1	1
U.S. Government-Sponsored Entities [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	100	120
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Fair  Value	100	121
Agency Mortgage-Backed Securities [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	889	769
Gross Unrealized Gains	22	29
Gross Unrealized Losses	(2)	0
Fair  Value	909	798
Agency Collateralized Mortgage Obligations [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	643	562
Gross Unrealized Gains	14	17
Gross Unrealized Losses	(2)	0
Fair  Value	655	579
Commercial Mortgage-Backed Securities [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	314	307
Gross Unrealized Gains	4	10
Gross Unrealized Losses	(3)	0
Fair  Value	315	317
States of the U.S. and Political Subdivisions (municipals) [Member]
Investment Securities Held To Maturity [Line Items]
Amortized Cost	1,095	1,108
Gross Unrealized Gains	39	48
Gross Unrealized Losses	(1)	0
Fair  Value	$ 1,133	$ 1,156

SECURITIES - Amortized Cost a_3

SECURITIES - Amortized Cost and Fair Value of Securities, by Contractual Maturities (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Securities [Line Items]
Available for sale, due in one year or less, amortized cost	$ 185
Available for sale, due after one year but within five years, amortized cost	70
Available for sale, due after five years but within ten years, amortized cost	127
Available for sale, due after ten years, amortized cost	84
Available for sale, with contractual maturities, amortized cost	466
Amortized Cost	3,110	$ 3,380
Available for sale, due in one year or less, fair value	186
Available for sale, due after one year but within five years, fair value	69
Available for sale, due after five years but within ten years, fair value	126
Available for sale, due after ten years, fair value	84
Available for sale, with contractual maturities, fair value	465
Total securities available for sale, fair value	3,166	3,463
Held to maturity, due in one year or less, amortized cost	100
Held to maturity, due after one year but within five years, amortized cost	21
Held to maturity, due after five years but within ten years, amortized cost	145
Held to maturity, due after ten years, amortized cost	931
Held to maturity, with contractual maturities, amortized cost	1,197
Amortized Cost	3,043	2,868
Held to maturity, due in one year or less, fair value	101
Held to maturity, due after one year but within five years, fair value	21
Held to maturity, due after five years but within ten years, fair value	147
Held to maturity, due after ten years, fair value	966
Held to maturity, with contractual maturities, fair value	1,235
Held to maturity, fair value, net	3,114	2,973
Agency Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Available-for-sale, amortized cost	1,074
Amortized Cost	1,074	959
Available for sale, fair value	1,103
Total securities available for sale, fair value	1,103	994
Held to maturity, amortized cost	889
Amortized Cost	889	769
Held to maturity, fair value	909
Held to maturity, fair value, net	909	798
Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Available-for-sale, amortized cost	1,242
Amortized Cost	1,242	1,094
Available for sale, fair value	1,263
Total securities available for sale, fair value	1,263	1,124
Held to maturity, amortized cost	643
Amortized Cost	643	562
Held to maturity, fair value	655
Held to maturity, fair value, net	655	579
Commercial Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Available-for-sale, amortized cost	328
Amortized Cost	328	361
Available for sale, fair value	335
Total securities available for sale, fair value	335	378
Held to maturity, amortized cost	314
Amortized Cost	314	307
Held to maturity, fair value	315
Held to maturity, fair value, net	$ 315	$ 317

SECURITIES - Schedule of Securi

SECURITIES - Schedule of Securities Pledged as Collateral (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Securities pledged (carrying value), to secure public deposits, trust deposits and for other purposes as required by law	$ 5,429	$ 5,384
Securities pledged (carrying value), as collateral for short-term borrowings	$ 434	$ 402
Securities pledged as a percent of total securities	94.40%	91.40%

SECURITIES - Fair Values and Un

SECURITIES - Fair Values and Unrealized Losses of Impaired Securities, by Length of Impairment (Detail) $ in Millions	Mar. 31, 2021USD ($)Security	Dec. 31, 2020USD ($)Security
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	27	7
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	17	17
Number of temporarily impaired available for sale securities | Security	44	24
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 702	$ 168
Temporarily impaired securities available for sale, 12 months or more, fair value	67	71
Temporarily impaired securities available for sale, fair value, total	769	239
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	(10)	(1)
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0	0
Temporarily impaired securities available for sale, unrealized losses, total	$ (10)	$ (1)
US Government Agencies [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	1	1
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	16	16
Number of temporarily impaired available for sale securities | Security	17	17
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 1	$ 13
Temporarily impaired securities available for sale, 12 months or more, fair value	65	69
Temporarily impaired securities available for sale, fair value, total	66	82
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	0	0
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0	0
Temporarily impaired securities available for sale, unrealized losses, total	$ 0	$ 0
U.S. Government-Sponsored Entities [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	2	1
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	0	0
Number of temporarily impaired available for sale securities | Security	2	1
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 74	$ 25
Temporarily impaired securities available for sale, 12 months or more, fair value	0	0
Temporarily impaired securities available for sale, fair value, total	74	25
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	(1)	0
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0	0
Temporarily impaired securities available for sale, unrealized losses, total	$ (1)	$ 0
Agency Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	2
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	0
Number of temporarily impaired available for sale securities | Security	2
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 103
Temporarily impaired securities available for sale, 12 months or more, fair value	0
Temporarily impaired securities available for sale, fair value, total	103
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	(1)
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0
Temporarily impaired securities available for sale, unrealized losses, total	$ (1)
Agency Collateralized Mortgage Obligations [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	10	5
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	0	0
Number of temporarily impaired available for sale securities | Security	10	5
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 399	$ 130
Temporarily impaired securities available for sale, 12 months or more, fair value	0	0
Temporarily impaired securities available for sale, fair value, total	399	130
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	(5)	(1)
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0	0
Temporarily impaired securities available for sale, unrealized losses, total	$ (5)	$ (1)
Commercial Mortgage-Backed Securities [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	4
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	0
Number of temporarily impaired available for sale securities | Security	4
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 103
Temporarily impaired securities available for sale, 12 months or more, fair value	0
Temporarily impaired securities available for sale, fair value, total	103
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	(2)
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0
Temporarily impaired securities available for sale, unrealized losses, total	$ (2)
States of the U.S. and Political Subdivisions (municipals) [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	8
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	0
Number of temporarily impaired available for sale securities | Security	8
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 22
Temporarily impaired securities available for sale, 12 months or more, fair value	0
Temporarily impaired securities available for sale, fair value, total	22
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	(1)
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0
Temporarily impaired securities available for sale, unrealized losses, total	$ (1)
Other Debt Securities [Member]
Schedule Of Securities [Line Items]
Number of temporarily impaired available for sale securities, Less than 1 year | Security	0	0
Number of temporarily impaired available for sale securities, Greater than 1 year | Security	1	1
Number of temporarily impaired available for sale securities | Security	1	1
Temporarily impaired securities available for sale, less than 12 months, fair value	$ 0	$ 0
Temporarily impaired securities available for sale, 12 months or more, fair value	2	2
Temporarily impaired securities available for sale, fair value, total	2	2
Temporarily impaired securities available for sale, less than 12 months, unrealized losses	0	0
Temporarily impaired securities available for sale, 12 months or more, unrealized losses	0	0
Temporarily impaired securities available for sale, unrealized losses, total	$ 0	$ 0

LOANS AND LEASES - Additional I

LOANS AND LEASES - Additional Information (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021USD ($)State	Dec. 31, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accrued interest receivable	$ 63.5	$ 62.9
Purchased with credit deterioration included with allowance for credit losses, amount	50.3
Purchased with credit deterioration, discount	110
Discount remaining	$ 44.3	50.9
Number of states, company operating financial services | State	7
Loans granted short-term modification due to COVID-19	$ 269
Restructured loans returned to performing status	3.9
Total loan on allowance	362	363
Pooled reserves for all other classes of loans	$ 3.9	4.1
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due period for loan to be in default	90 days
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Past due period for loan to be in default	12 months
SBA-Guaranteed Loan Servicing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Guaranteed percentage	100.00%
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of OREO through foreclosure	$ 1.6	2.5
Mortgage loans on real estate, foreclosure	7.6	8.2
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan on allowance	79	81	$ 88	$ 53
Commercial and Industrial [Member] | Paycheck Protection Program Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to customers	2,500	2,200
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, collateral dependent	85
Commercial Loan [Member] | Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold for loans whose terms have been modified in a trouble debt restructuring, non accrual	1
Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan on allowance	281	280	$ 254	$ 133
Total Commercial Loans and Leases [Member] | Specific Reserves for Commercial Troubled Debt Restructurings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan on allowance	1.6	2.8
Total Commercial Loans and Leases [Member] | Pooled Reserves For Commercial Troubled Debt Restructurings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan on allowance	$ 2.5	$ 2.5

LOANS AND LEASES - Net of Unear

LOANS AND LEASES - Net of Unearned Income (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	$ 25,532	$ 25,459
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	9,799	9,731
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	7,401	7,214
Commercial Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	471	485
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	25	40
Total Commercial Loans and Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	17,696	17,470
Direct Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	2,025	2,020
Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	3,329	3,433
Indirect Installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	1,201	1,218
Consumer Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	1,281	1,318
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Amortized cost loans and leases, carrying amount	$ 7,836	$ 7,989

LOANS AND LEASES - Commercial R

LOANS AND LEASES - Commercial Real Estate Loans (Detail) - Loan Portfolio Diversification Risk [Member] - Commercial Real Estate Loans [Member]	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Owner-Occupied [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Percent of total loans and leases	28.10%	28.10%
Non-Owner-Occupied [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Percent of total loans and leases	71.90%	71.90%

LOANS AND LEASES - Origination

LOANS AND LEASES - Origination Year (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 2,011	$ 7,565
Fiscal year before current fiscal year	6,812	4,429
Two years before current fiscal year	4,171	2,837
Three years before current fiscal year	2,642	2,281
Four years before current fiscal year	2,103	1,800
Prior	5,320	3,917
Revolving Loans Amortized Cost Basis	2,473	2,630
Total Loans and Leases	25,532	25,459
Commercial Real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	328	1,892
Fiscal year before current fiscal year	1,896	1,916
Two years before current fiscal year	1,939	1,244
Three years before current fiscal year	1,214	1,166
Four years before current fiscal year	1,105	1,074
Prior	3,162	2,266
Revolving Loans Amortized Cost Basis	155	173
Total Loans and Leases	9,799	9,731
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	323	1,879
Fiscal year before current fiscal year	1,876	1,854
Two years before current fiscal year	1,874	1,135
Three years before current fiscal year	1,080	927
Four years before current fiscal year	881	888
Prior	2,680	1,911
Revolving Loans Amortized Cost Basis	145	163
Total Loans and Leases	8,859	8,757
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	5	9
Fiscal year before current fiscal year	12	30
Two years before current fiscal year	32	80
Three years before current fiscal year	93	158
Four years before current fiscal year	151	70
Prior	191	163
Revolving Loans Amortized Cost Basis	5	4
Total Loans and Leases	489	514
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	4
Fiscal year before current fiscal year	8	32
Two years before current fiscal year	33	29
Three years before current fiscal year	41	81
Four years before current fiscal year	73	116
Prior	291	192
Revolving Loans Amortized Cost Basis	5	6
Total Loans and Leases	451	460
Commercial and Industrial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,118	3,324
Fiscal year before current fiscal year	2,682	1,056
Two years before current fiscal year	969	668
Three years before current fiscal year	627	376
Four years before current fiscal year	353	136
Prior	465	383
Revolving Loans Amortized Cost Basis	1,187	1,271
Total Loans and Leases	7,401	7,214
Commercial and Industrial [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,116	3,286
Fiscal year before current fiscal year	2,642	1,007
Two years before current fiscal year	921	590
Three years before current fiscal year	561	304
Four years before current fiscal year	280	120
Prior	354	311
Revolving Loans Amortized Cost Basis	1,030	1,095
Total Loans and Leases	6,904	6,713
Commercial and Industrial [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	30
Fiscal year before current fiscal year	32	23
Two years before current fiscal year	20	13
Three years before current fiscal year	9	28
Four years before current fiscal year	28	10
Prior	67	35
Revolving Loans Amortized Cost Basis	53	79
Total Loans and Leases	209	218
Commercial and Industrial [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	2	8
Fiscal year before current fiscal year	8	26
Two years before current fiscal year	28	65
Three years before current fiscal year	57	44
Four years before current fiscal year	45	6
Prior	44	37
Revolving Loans Amortized Cost Basis	104	97
Total Loans and Leases	288	283
Commercial Leases [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	34	186
Fiscal year before current fiscal year	166	137
Two years before current fiscal year	128	89
Three years before current fiscal year	78	61
Four years before current fiscal year	56	7
Prior	9	5
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	471	485
Commercial Leases [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	34	178
Fiscal year before current fiscal year	158	134
Two years before current fiscal year	124	83
Three years before current fiscal year	73	56
Four years before current fiscal year	52	5
Prior	6	3
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	447	459
Commercial Leases [Member] | Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
Fiscal year before current fiscal year	0	1
Two years before current fiscal year	1	4
Three years before current fiscal year	3	4
Four years before current fiscal year	3	1
Prior	3	2
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	10	13
Commercial Leases [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	7
Fiscal year before current fiscal year	8	2
Two years before current fiscal year	3	2
Three years before current fiscal year	2	1
Four years before current fiscal year	1	1
Prior	0	0
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	14	13
Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	4	5
Revolving Loans Amortized Cost Basis	15	35
Total Loans and Leases	25	40
Other [Member] | Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	6	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	4	4
Revolving Loans Amortized Cost Basis	15	35
Total Loans and Leases	25	39
Other [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	0	1
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	0	1
Total Commercial Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,486	5,402
Fiscal year before current fiscal year	4,744	3,109
Two years before current fiscal year	3,036	2,001
Three years before current fiscal year	1,919	1,603
Four years before current fiscal year	1,514	1,217
Prior	3,640	2,659
Revolving Loans Amortized Cost Basis	1,357	1,479
Total Loans and Leases	17,696	17,470
Direct Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	154	706
Fiscal year before current fiscal year	676	338
Two years before current fiscal year	307	202
Three years before current fiscal year	183	144
Four years before current fiscal year	131	173
Prior	574	456
Revolving Loans Amortized Cost Basis	0	1
Total Loans and Leases	2,025	2,020
Direct Installment [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	154	706
Fiscal year before current fiscal year	676	337
Two years before current fiscal year	306	200
Three years before current fiscal year	182	143
Four years before current fiscal year	130	171
Prior	560	442
Revolving Loans Amortized Cost Basis	0	1
Total Loans and Leases	2,008	2,000
Direct Installment [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	1
Two years before current fiscal year	1	2
Three years before current fiscal year	1	1
Four years before current fiscal year	1	2
Prior	14	14
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	17	20
Residential Mortgages [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	248	1,080
Fiscal year before current fiscal year	1,034	712
Two years before current fiscal year	588	290
Three years before current fiscal year	242	382
Four years before current fiscal year	331	336
Prior	885	632
Revolving Loans Amortized Cost Basis	1	1
Total Loans and Leases	3,329	3,433
Residential Mortgages [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	248	1,079
Fiscal year before current fiscal year	1,033	707
Two years before current fiscal year	586	283
Three years before current fiscal year	239	378
Four years before current fiscal year	327	330
Prior	856	603
Revolving Loans Amortized Cost Basis	1	1
Total Loans and Leases	3,290	3,381
Residential Mortgages [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
Fiscal year before current fiscal year	1	5
Two years before current fiscal year	2	7
Three years before current fiscal year	3	4
Four years before current fiscal year	4	6
Prior	29	29
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	39	52
Indirect Installment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	122	373
Fiscal year before current fiscal year	354	263
Two years before current fiscal year	235	336
Three years before current fiscal year	290	149
Four years before current fiscal year	124	69
Prior	76	28
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	1,201	1,218
Indirect Installment [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	122	372
Fiscal year before current fiscal year	353	260
Two years before current fiscal year	233	332
Three years before current fiscal year	289	147
Four years before current fiscal year	123	67
Prior	75	27
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	1,195	1,205
Indirect Installment [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	1
Fiscal year before current fiscal year	1	3
Two years before current fiscal year	2	4
Three years before current fiscal year	1	2
Four years before current fiscal year	1	2
Prior	1	1
Revolving Loans Amortized Cost Basis	0	0
Total Loans and Leases	6	13
Consumer Lines of Credit [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	4
Fiscal year before current fiscal year	4	7
Two years before current fiscal year	5	8
Three years before current fiscal year	8	3
Four years before current fiscal year	3	5
Prior	145	142
Revolving Loans Amortized Cost Basis	1,115	1,149
Total Loans and Leases	1,281	1,318
Consumer Lines of Credit [Member] | Current [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1	4
Fiscal year before current fiscal year	4	7
Two years before current fiscal year	5	8
Three years before current fiscal year	8	3
Four years before current fiscal year	3	5
Prior	132	127
Revolving Loans Amortized Cost Basis	1,114	1,146
Total Loans and Leases	1,267	1,300
Consumer Lines of Credit [Member] | Past Due [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Fiscal year before current fiscal year	0	0
Two years before current fiscal year	0	0
Three years before current fiscal year	0	0
Four years before current fiscal year	0	0
Prior	13	15
Revolving Loans Amortized Cost Basis	1	3
Total Loans and Leases	14	18
Consumer Loan [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	525	2,163
Fiscal year before current fiscal year	2,068	1,320
Two years before current fiscal year	1,135	836
Three years before current fiscal year	723	678
Four years before current fiscal year	589	583
Prior	1,680	1,258
Revolving Loans Amortized Cost Basis	1,116	1,151
Total Loans and Leases	$ 7,836	$ 7,989

LOANS AND LEASES - Age Analysis

LOANS AND LEASES - Age Analysis of Past Due Loans (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	$ 25,532	$ 25,459
Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	9,799	9,731
Commercial and Industrial [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,401	7,214
Commercial Leases [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	471	485
Other [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	25	40
Total Commercial Loans [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	17,696	17,470
Direct Installment [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	2,025	2,020
Residential Mortgages [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	3,329	3,433
Indirect Installment [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,201	1,218
Consumer Lines of Credit [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	1,281	1,318
Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases	7,836	7,989
Loans and Leases [Member]
Financing Receivable, Past Due [Line Items]
Past Due	205	258
Non-accrual loans	157	170
Current	25,327	25,201
Total Loans and Leases	25,532	25,459
Non-accrual with No ACL	45	52
Loans and Leases [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	38	72
Loans and Leases [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	10	16
Loans and Leases [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Past Due	86	98
Non-accrual loans	78	85
Current	9,713	9,633
Total Loans and Leases	9,799	9,731
Non-accrual with No ACL	30	36
Loans and Leases [Member] | Commercial Real Estate [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	8	13
Loans and Leases [Member] | Commercial Real Estate [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	0
Loans and Leases [Member] | Commercial and Industrial [Member]
Financing Receivable, Past Due [Line Items]
Past Due	38	52
Non-accrual loans	36	44
Current	7,363	7,162
Total Loans and Leases	7,401	7,214
Non-accrual with No ACL	15	16
Loans and Leases [Member] | Commercial and Industrial [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	2	8
Loans and Leases [Member] | Commercial and Industrial [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	0
Loans and Leases [Member] | Commercial Leases [Member]
Financing Receivable, Past Due [Line Items]
Past Due	5	4
Non-accrual loans	2	2
Current	466	481
Total Loans and Leases	471	485
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Commercial Leases [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	3	2
Loans and Leases [Member] | Commercial Leases [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	0
Loans and Leases [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	1
Non-accrual loans	0	1
Current	25	39
Total Loans and Leases	25	40
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Other [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	0
Loans and Leases [Member] | Other [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	0
Loans and Leases [Member] | Total Commercial Loans [Member]
Financing Receivable, Past Due [Line Items]
Past Due	129	155
Non-accrual loans	116	132
Current	17,567	17,315
Total Loans and Leases	17,696	17,470
Non-accrual with No ACL	45	52
Loans and Leases [Member] | Total Commercial Loans [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	13	23
Loans and Leases [Member] | Total Commercial Loans [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	0
Loans and Leases [Member] | Direct Installment [Member]
Financing Receivable, Past Due [Line Items]
Past Due	17	20
Non-accrual loans	11	11
Current	2,008	2,000
Total Loans and Leases	2,025	2,020
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Direct Installment [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	5	7
Loans and Leases [Member] | Direct Installment [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	1	2
Loans and Leases [Member] | Residential Mortgages [Member]
Financing Receivable, Past Due [Line Items]
Past Due	39	52
Non-accrual loans	21	18
Current	3,290	3,381
Total Loans and Leases	3,329	3,433
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Residential Mortgages [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	12	23
Loans and Leases [Member] | Residential Mortgages [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	6	11
Loans and Leases [Member] | Indirect Installment [Member]
Financing Receivable, Past Due [Line Items]
Past Due	6	13
Non-accrual loans	2	2
Current	1,195	1,205
Total Loans and Leases	1,201	1,218
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Indirect Installment [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	4	10
Loans and Leases [Member] | Indirect Installment [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	0	1
Loans and Leases [Member] | Consumer Lines of Credit [Member]
Financing Receivable, Past Due [Line Items]
Past Due	14	18
Non-accrual loans	7	7
Current	1,267	1,300
Total Loans and Leases	1,281	1,318
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Consumer Lines of Credit [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	4	9
Loans and Leases [Member] | Consumer Lines of Credit [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	3	2
Loans and Leases [Member] | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Past Due	76	103
Non-accrual loans	41	38
Current	7,760	7,886
Total Loans and Leases	7,836	7,989
Non-accrual with No ACL	0	0
Loans and Leases [Member] | Consumer Loan [Member] | 30-89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Past Due	25	49
Loans and Leases [Member] | Consumer Loan [Member] | Equal to Greater than 90 Days Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Past Due	$ 10	$ 16

LOANS AND LEASES - Non-Performi

LOANS AND LEASES - Non-Performing Assets (Detail) - Non-Performing [Member] - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 157	$ 170
Total non-performing loans	157	170
Other real estate owned	9	10
Non Performing Assets	$ 166	$ 180
Non-performing loans / total loans and leases	0.62%	0.67%
Non-performing assets + 90 days past due + OREO / total loans and leases + OREO	0.68%	0.77%
Past due	90 days	90 days

LOANS AND LEASES - Summary of P

LOANS AND LEASES - Summary of Payment Status of TDRs (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings ("TDRs")	$ 98	$ 91
Performing [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings ("TDRs")	58	58
Non-Accrual [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled debt restructurings ("TDRs")	$ 40	$ 33

LOANS AND LEASES - Troubled Deb

LOANS AND LEASES - Troubled Debt Restructurings (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)Contract	Mar. 31, 2020USD ($)Contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	34	60
Pre- Modification Outstanding Recorded Investment	$ 19	$ 5
Post- Modification Outstanding Recorded Investment	$ 19	$ 4
Total Commercial Loans and Leases [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	12	12
Pre- Modification Outstanding Recorded Investment	$ 17	$ 2
Post- Modification Outstanding Recorded Investment	$ 17	$ 1
Commercial Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	11	5
Pre- Modification Outstanding Recorded Investment	$ 17	$ 1
Post- Modification Outstanding Recorded Investment	$ 17	$ 1
Commercial and Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	1	7
Pre- Modification Outstanding Recorded Investment	$ 0	$ 1
Post- Modification Outstanding Recorded Investment	$ 0	$ 0
Consumer Loan [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	22	48
Pre- Modification Outstanding Recorded Investment	$ 2	$ 3
Post- Modification Outstanding Recorded Investment	$ 2	$ 3
Direct Installment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	10	19
Pre- Modification Outstanding Recorded Investment	$ 0	$ 2
Post- Modification Outstanding Recorded Investment	$ 0	$ 2
Residential Mortgages [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	2	14
Pre- Modification Outstanding Recorded Investment	$ 1	$ 1
Post- Modification Outstanding Recorded Investment	$ 1	$ 1
Consumer Lines of Credit [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	10	15
Pre- Modification Outstanding Recorded Investment	$ 1	$ 0
Post- Modification Outstanding Recorded Investment	$ 1	$ 0

LOANS AND LEASES - Originated T

LOANS AND LEASES - Originated Troubled Debt Restructurings, Payment Default (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)Contract	Mar. 31, 2020USD ($)Contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	2	17
Recorded Investment | $	$ 0	$ 4
Total Commercial Loans and Leases [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	1	12
Recorded Investment | $	$ 0	$ 4
Commercial Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract		10
Recorded Investment | $		$ 4
Commercial and Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	1	2
Recorded Investment | $	$ 0	$ 0
Consumer Loan [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	1	5
Recorded Investment | $	$ 0	$ 0
Direct Installment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract		4
Recorded Investment | $		$ 0
Residential Mortgages [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract	1	1
Recorded Investment | $	$ 0	$ 0

ALLOWANCE FOR CREDIT LOSSES O_3

ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES - Narrative (Details) - USD ($) $ in Millions	Jan. 01, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' equity attributable to parent		$ 4,974	$ 4,842	$ 4,959	$ 4,883
Financing receivable, allowance for credit loss, period increase (decrease)	$ 105			(1.1)
Allowance for credit loss		$ 362		$ 363
Percentage of growth, gross domestic product				4.00%
Percentage of unemployment		5.00%		6.00%
Percentage of contraction, gross domestic product, current year		6.00%
Percentage of contraction, gross domestic product, next fiscal year		2.00%
Financing receivable, allowance for credit loss, period increase (decrease), percentage				(0.30%)
Financing receivable, allowance for credit loss, ratio		1.42%		1.43%
Provision for credit losses		$ 5.9
Financing receivable, allowance for credit loss, write-off		7.1	5.7
Allowance For Credit Losses on Loans and Leases [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss		362	343	$ 363	196
Impact of ASC 326 Adoption [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' equity attributable to parent			(50)
Retained Earnings [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' equity attributable to parent		$ 921	754	$ 869	$ 798
Retained Earnings [Member] | Impact of ASC 326 Adoption [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' equity attributable to parent			$ (50)
Accounting Standards Update 2016-13 [Member] | Retained Earnings [Member] | Impact of ASC 326 Adoption [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Stockholders' equity attributable to parent	(50.6)
Longer Duration Loans and Gross Up [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing receivable, allowance for credit loss, period increase (decrease)	50
Unfunded Loan Commitment [Member] | Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss	$ 10

ALLOWANCE FOR CREDIT LOSSES O_4

ALLOWANCE FOR CREDIT LOSSES ON LOANS AND LEASES - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Millions	Jan. 01, 2020	Mar. 31, 2021	Mar. 31, 2020
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period		$ 363
Provision for Credit Losses		6	$ 48
Balance at End of Period		362
Unfunded Loan Commitment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	$ 3	14	3
Charge- Offs		0	0
Recoveries		0	0
Net Charge- Offs		0	0
Provision for Credit Losses		0	1
Other adjustments:		0	1
ASC 326 Adoption Impact	10
Initial ACL on PCD Loans			0
Balance at End of Period		14	14
Unfunded Loan Commitment [Member] | Other Non-interest Expense
Allowance for Loan and Lease Losses [Roll Forward]
Balance at End of Period			1
Commercial Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	60	181	60
Charge- Offs		(1)	(2)
Recoveries		1	4
Net Charge- Offs		0	2
Provision for Credit Losses		3	12
ASC 326 Adoption Impact	38
Initial ACL on PCD Loans			40
Balance at End of Period		184	152
Commercial and Industrial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	53	81	53
Charge- Offs		(8)	(4)
Recoveries		1	1
Net Charge- Offs		(7)	(3)
Provision for Credit Losses		5	26
ASC 326 Adoption Impact	8
Initial ACL on PCD Loans			4
Balance at End of Period		79	88
Commercial Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	11	17	11
Charge- Offs		0	0
Recoveries		1	0
Net Charge- Offs		1	0
Provision for Credit Losses		(1)	2
ASC 326 Adoption Impact	0
Initial ACL on PCD Loans			0
Balance at End of Period		17	13
Other [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	9	1	9
Charge- Offs		(1)	(1)
Recoveries		1	0
Net Charge- Offs		0	(1)
Provision for Credit Losses		0	2
ASC 326 Adoption Impact	(9)
Initial ACL on PCD Loans			0
Balance at End of Period		1	1
Total Commercial Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	133	280	133
Charge- Offs		(10)	(7)
Recoveries		4	5
Net Charge- Offs		(6)	(2)
Provision for Credit Losses		7	42
ASC 326 Adoption Impact	37
Initial ACL on PCD Loans			44
Balance at End of Period		281	254
Total Commercial Loans and Leases [Member] | Unfunded Loan Commitment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Provision for Credit Losses		0	0
ASC 326 Adoption Impact		0	8
Direct Installment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	13	26	13
Charge- Offs		0	(1)
Recoveries		0	0
Net Charge- Offs		0	(1)
Provision for Credit Losses		0	3
ASC 326 Adoption Impact	10
Initial ACL on PCD Loans			1
Balance at End of Period		26	26
Residential Mortgages [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	22	34	22
Charge- Offs		0	0
Recoveries		0	0
Net Charge- Offs		0	0
Provision for Credit Losses		(2)	(1)
ASC 326 Adoption Impact	6
Initial ACL on PCD Loans			4
Balance at End of Period		32	31
Indirect Installment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	19	11	19
Charge- Offs		(2)	(3)
Recoveries		1	1
Net Charge- Offs		(1)	(2)
Provision for Credit Losses		1	2
ASC 326 Adoption Impact	2
Initial ACL on PCD Loans			0
Balance at End of Period		11	21
Consumer Lines of Credit [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	9	12	9
Charge- Offs		0	(1)
Recoveries		0	0
Net Charge- Offs		0	(1)
Provision for Credit Losses		0	2
ASC 326 Adoption Impact	0
Initial ACL on PCD Loans			1
Balance at End of Period		12	11
Consumer Lines of Credit [Member] | Unfunded Loan Commitment [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Provision for Credit Losses		0	0
ASC 326 Adoption Impact		0	2
Consumer Loan [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	63	83	63
Charge- Offs		(2)	(5)
Recoveries		1	1
Net Charge- Offs		(1)	(4)
Provision for Credit Losses		(1)	6
ASC 326 Adoption Impact	18
Initial ACL on PCD Loans			6
Balance at End of Period		81	89
Allowance For Credit Losses on Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	196	363	196
Charge- Offs		(12)	(12)
Recoveries		5	6
Net Charge- Offs		(7)	(6)
Provision for Credit Losses		6	48
ASC 326 Adoption Impact	55
Initial ACL on PCD Loans			50
Balance at End of Period		362	343
Allowance For Credit Losses on Loans and Leases and Unfunded Loans Commitments [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at Beginning of Period	199	377	199
Charge- Offs		(12)	(12)
Recoveries		5	6
Net Charge- Offs		(7)	(6)
Provision for Credit Losses		6	49
ASC 326 Adoption Impact	$ 65
Initial ACL on PCD Loans			50
Balance at End of Period		$ 376	$ 357

LOAN SERVICING - Activity in MS

LOAN SERVICING - Activity in MSR (Detail) - Mortgage Servicing Rights [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Servicing Assets at Fair Value [Line Items]
Mortgage loans sold with servicing retained	$ 4,670		$ 4,653
Mortgage loans sold with servicing retained	506	$ 260
Pretax net gains resulting from above loan sales	17	7
Mortgage banking operations	3	3
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of period	35.6	42.6
Additions	5.2	2.5
Payoffs and curtailments	(4.1)	(1.9)
(Impairment charge) / recovery	2.5	(7.7)
Amortization	(0.6)	(0.6)
Balance at end of period	38.6	34.9
Loan servicing rights, fair value, start	35.6	45
Loan servicing rights, fair value, end	40.2	$ 34.9
Valuation allowance for servicing rights	$ 4.8		$ 7.3

LOAN SERVICING - Sensitivity of

LOAN SERVICING - Sensitivity of Fair Value to Changes in key Assumptions (Detail) - Mortgage Servicing Rights [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Weighted average life (months)	71 months 8 days	66 months 17 days
Constant prepayment rate (annualized)	12.60%	13.40%
Discount rate	9.50%	9.50%
Sensitivity analysis of fair value, change in interest rates, plus .25%	$ 3	$ 2
Sensitivity analysis of fair value, change in interest rates, plus .50%	5	4
Sensitivity analysis of fair value, change in interest rates, minus .25%	(3)	(2)
Sensitivity analysis of fair value, change in interest rates, minus .50%	$ (6)	$ (3)

OPERATING LEASES (Details)

OPERATING LEASES (Details) $ in Millions	Mar. 31, 2021USD ($)
Leases [Abstract]
Operating lease, right-of-use asset, statement of financial position [extensible list]	Other assets
Operating lease, liability, statement of financial position [extensible list]	Other liabilities
Operating lease, right-of-use asset	$ 122.5
Operating lease, liability	130.4
Operating lease, lease not yet commenced, expense	$ 21.5
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, operating lease, lease not yet commenced, term of contract	3 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, operating lease, lease not yet commenced, term of contract	20 years

OPERATING LEASES - Lease Expens

OPERATING LEASES - Lease Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 7	$ 7
Variable lease cost	1	1
Total lease cost	$ 8	$ 8

OPERATING LEASES - Other Inform

OPERATING LEASES - Other Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease, Cash paid for amounts included in the measurement of lease liabilities, operating	$ 7	$ 6
Operating lease, right-of-use assets obtained in exchange for lease obligations	$ 0	$ 4
Operating lease, weighted average remaining lease term (in years)	9 years 4 months 20 days	9 years 7 months 20 days
Operating lease, weighted average discount rate, percent	2.60%	2.90%

OPERATING LEASES - Maturities (

OPERATING LEASES - Maturities (Details) $ in Millions	Mar. 31, 2021USD ($)
Leases [Abstract]
2021	$ 19
2022	22
2023	17
2024	16
2025	12
Later years	64
Total lease payments	150
Less: imputed interest	(20)
Present value of lease liabilities	$ 130.4

VARIABLE INTEREST ENTITIES - As

VARIABLE INTEREST ENTITIES - Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Variable Interest Entity [Line Items]
Assets	$ 38,475	$ 37,354	$ 35,049
Liabilities	33,501	32,395
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	142	146
Liabilities	114	119
Maximum Exposure to Loss	141	145
Trust Preferred Securities [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	1	1
Liabilities	66	66
Maximum Exposure to Loss	0	0
Affordable Housing Tax Credit Partnerships [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	115	119
Liabilities	41	45
Maximum Exposure to Loss	115	119
Other Investments [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Assets	26	26
Liabilities	7	8
Maximum Exposure to Loss	$ 26	$ 26

VARIABLE INTEREST ENTITIES - Af

VARIABLE INTEREST ENTITIES - Affordable Housing Tax Credit Investments And Related Unfunded Commitments (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Proportional amortization method investments included in other assets	$ 71	$ 71
Equity method investments included in other assets	3	3
Total LIHTC investments included in other assets	74	74
Unfunded LIHTC commitments	$ 41	$ 45

VARIABLE INTEREST ENTITIES - In

VARIABLE INTEREST ENTITIES - Income Statement Effect (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Non-Interest Income
Amortization of tax credit investments under equity method, net of tax benefit	$ 0	$ 0
Provision for income taxes:
Amortization of LIHTC investments under proportional method	3	3
Low-income housing tax credits	(3)	(3)
Other tax benefits related to tax credit investments	(1)	(1)
Amortization Method Qualified Affordable Housing Project Investments, Provision For Income Tax	$ (1)	$ (1)

BORROWINGS - Summary of Short-T

BORROWINGS - Summary of Short-Term Borrowings (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Securities sold under repurchase agreements	$ 435	$ 403
Federal Home Loan Bank advances	1,130	1,280
Subordinated notes	122	121
Total short-term borrowings	$ 1,687	$ 1,804

BORROWINGS - Additional Informa

BORROWINGS - Additional Information (Detail) - USD ($) $ in Billions	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Short-term advances	$ 1.1	$ 1.3
Short-term advances, percentage bearing fixed interest rate	100.00%	100.00%
FHLB [Member]
Debt Instrument [Line Items]
Credit available with FHLB	$ 8.3
Credit with FHLB utilized	$ 1.5
Minimum [Member] | FHLB [Member]
Debt Instrument [Line Items]
Effective interest rates	0.26%	0.30%
Maximum [Member] | FHLB [Member]
Debt Instrument [Line Items]
Effective interest rates	0.29%	0.34%

BORROWINGS - Summary of Long-Te

BORROWINGS - Summary of Long-Term Borrowings (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Federal Home Loan Bank advances	$ 400	$ 400
Senior notes	299	299
Subordinated notes	78	81
Junior subordinated debt	66	66
Other subordinated debt	248	249
Total long-term borrowings	$ 1,091	$ 1,095

BORROWINGS - Schedule of Subord

BORROWINGS - Schedule of Subordinated Debt (Details)	3 Months Ended
	Mar. 31, 2021USD ($)
Debt Instrument [Line Items]
Aggregate Principal Amount Issued	$ 558,000,000
Net Proceeds	560,000,000
Carrying Value	$ 547,000,000
2.20% Senior Notes due February 24, 2023 [Member]
Debt Instrument [Line Items]
Interest Rate	2.20%
Aggregate Principal Amount Issued	$ 300,000,000
Net Proceeds	298,000,000
Carrying Value	$ 299,000,000
4.95% Fixed-To-Floating Rate Subordinated Notes due 2029 [Member]
Debt Instrument [Line Items]
Interest Rate	4.95%
Aggregate Principal Amount Issued	$ 120,000,000
Net Proceeds	118,000,000
Carrying Value	$ 118,000,000
4.875% Subordinated Notes due 2025 [Member]
Debt Instrument [Line Items]
Interest Rate	4.875%
Aggregate Principal Amount Issued	$ 100,000,000
Net Proceeds	98,000,000
Carrying Value	$ 99,000,000
7.625% Subordinated Notes due August 12, 2023 [Member] | Yadkin Financial Corporation (YDKN) [Member]
Debt Instrument [Line Items]
Interest Rate	7.625%
Aggregate Principal Amount Issued	$ 38,000,000
Net Proceeds	46,000,000
Carrying Value	$ 31,000,000

BORROWINGS - Junior Subordinate

BORROWINGS - Junior Subordinated Debt Trusts (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 66	$ 66
Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	72
Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	3
F.N.B. Statutory Trust II [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
Interest Rate	1.83%
F.N.B. Statutory Trust II [Member] | London Interbank Offered Rate (LIBOR) [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.65%
F.N.B. Statutory Trust II [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
F.N.B. Statutory Trust II [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1
Yadkin Valley Statutory Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
Interest Rate	1.50%
Yadkin Valley Statutory Trust I [Member] | London Interbank Offered Rate (LIBOR) [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.32%
Yadkin Valley Statutory Trust I [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 25
Yadkin Valley Statutory Trust I [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	1
FNB Financial Services Capital Trust I [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 22
Interest Rate	1.66%
FNB Financial Services Capital Trust I [Member] | London Interbank Offered Rate (LIBOR) [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.46%
FNB Financial Services Capital Trust I [Member] | Trust Preferred Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 25
FNB Financial Services Capital Trust I [Member] | Common Securities [Member]
Subordinated Borrowing [Line Items]
Junior subordinated debt	$ 1

DERIVATIVE INSTRUMENTS AND HE_3

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Notional Amounts and Gross Fair Values (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Notional amount	$ 12,619	$ 12,480
Derivative asset, not offset against collateral	6	3
Derivative liability, not offset against collateral	25	37
Derivative asset, not subject to master netting arrangement	230	373
Derivative liability, not subject to master netting arrangement	34	3
Fair value, asset	236	376
Fair value, liability	59	40
Interest rate contracts - designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not offset against collateral	2	3
Derivative liability, not offset against collateral	0	0
Interest rate swaps - not designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not offset against collateral	4	0
Derivative liability, not offset against collateral	25	37
Derivative asset, not subject to master netting arrangement	211	349
Derivative liability, not subject to master netting arrangement	32	0
Interest rate lock commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not subject to master netting arrangement	10	24
Derivative liability, not subject to master netting arrangement	1	0
Forward delivery commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, not subject to master netting arrangement	9	0
Derivative liability, not subject to master netting arrangement	0	2
Credit risk contracts - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	291.9
Derivative asset, not subject to master netting arrangement	0	0
Derivative liability, not subject to master netting arrangement	1	1
Subject to Master Netting Arrangements [Member]
Derivatives, Fair Value [Line Items]
Notional amount	6,127	6,221
Subject to Master Netting Arrangements [Member] | Interest rate contracts - designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	1,180	1,430
Subject to Master Netting Arrangements [Member] | Interest rate swaps - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	4,947	4,791
Not Subject to Master Netting Arrangements [Member]
Derivatives, Fair Value [Line Items]
Notional amount	6,492	6,259
Not Subject to Master Netting Arrangements [Member] | Interest rate swaps - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	4,947	4,791
Not Subject to Master Netting Arrangements [Member] | Interest rate lock commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	549	531
Not Subject to Master Netting Arrangements [Member] | Forward delivery commitments – not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	571	500
Not Subject to Master Netting Arrangements [Member] | Credit risk contracts - not designated [Member]
Derivatives, Fair Value [Line Items]
Notional amount	$ 425	$ 437

DERIVATIVE INSTRUMENTS AND HE_4

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Amounts Reclassified from AOCI (Detail) - Interest rate contracts [Member] - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives	$ 5,000,000	$ (45,000,000)
Amount of Gain (Loss) Reclassified from AOCI into Income	0	0
Interest Income (Expense) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount of Gain (Loss) Reclassified from AOCI into Income	$ (5,000,000)	$ (1,000,000)

DERIVATIVE INSTRUMENTS AND HE_5

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Effect of Cash Flow Hedging on Income Statement (Detail) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative [Line Items]
Interest Income - Loans and Leases	$ 221,000,000	$ 266,000,000
Interest Expense - Short-Term Borrowings	7,000,000	14,000,000
Interest rate contracts [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into net income	0	0
Interest Income - Loans and Leases [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into net income	0	0
Interest Expense - Short-Term Borrowings [Member] | Interest rate contracts [Member]
Derivative [Line Items]
Amount of gain (loss) reclassified from AOCI into net income	$ (5,000,000)	$ (1,000,000)

DERIVATIVE INSTRUMENTS AND HE_6

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative [Line Items]
Notional amount	$ 12,619,000,000		$ 12,480,000,000
Additional amount in excess of posted collateral required in case of breached agreements	$ 100,000		300,000
Interest rate contracts [Member]
Derivative [Line Items]
Maximum length of time hedged in interest rate cash flow hedge	3 years 7 months 6 days
Period to reclassification of cash flow hedge gain loss	12 months
Derivative gains to be reclassified within twelve months	$ 18,000,000
Derivative gains to be reclassified within twelve months, net of tax	14,000,000
Derivative gain or losses excluded from assessment of hedge effectiveness	0
Amount of gain (loss) reclassified from AOCI into net income	0	$ 0
Credit risk contracts - not designated [Member]
Derivative [Line Items]
Notional amount	291,900,000
Maximum exposure under credit risk agreement assuming customer default	300,000		600,000
Credit risk derivatives, purchased at fair value	100,000		200,000
Credit risk derivatives, sold at fair value	$ 300,000		$ 600,000
Credit risk contracts - not designated [Member] | Minimum [Member]
Derivative [Line Items]
Risk participation agreements, term	1 month
Credit risk contracts - not designated [Member] | Maximum [Member]
Derivative [Line Items]
Risk participation agreements, term	20 years

DERIVATIVE INSTRUMENTS AND HE_7

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Effect of Derivative Financial Instruments on Income Statement (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest Rate Swap [Member] | Non-interest income - other [Member]
Derivative [Line Items]
Derivative financial instrument, net	$ 0	$ 0
Interest Rate Lock Commitments [Member] | Mortgage banking operations [Member]
Derivative [Line Items]
Derivative financial instrument, net	0	0
Forward Delivery Contracts [Member] | Mortgage banking operations [Member]
Derivative [Line Items]
Derivative financial instrument, net	9	(1)
Credit Risk Contract [Member] | Non-interest income - other [Member]
Derivative [Line Items]
Derivative financial instrument, net	$ 0	$ 0

DERIVATIVE INSTRUMENTS AND HE_8

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Derivative Assets (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	$ 6	$ 3
Financial Instruments	0	0
Cash Collateral	6	3
Net Amount	0	0
Interest rate contracts - designated [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	2	3
Financial Instruments	0	0
Cash Collateral	2	3
Net Amount	0	0
Interest rate swaps - not designated [Member]
Derivative [Line Items]
Net Amount Presented in the Balance Sheet	4	$ 0
Financial Instruments	0
Cash Collateral	4
Net Amount	$ 0

DERIVATIVE INSTRUMENTS AND HE_9

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Derivative Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Net Amount Presented in the Consolidated Balance Sheets	$ 25	$ 37
Financial Instruments	0	0
Cash Collateral	25	37
Net Amount	0	0
Interest rate contracts - designated [Member]
Derivative [Line Items]
Net Amount Presented in the Consolidated Balance Sheets	0	0
Interest rate swaps - not designated [Member]
Derivative [Line Items]
Net Amount Presented in the Consolidated Balance Sheets	25	37
Financial Instruments	0	0
Cash Collateral	25	37
Net Amount	$ 0	$ 0

COMMITMENTS, CREDIT RISK AND _3

COMMITMENTS, CREDIT RISK AND CONTINGENCIES - Off-Balance Sheet Credit Risk (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Extended credit and standby letters of credit	$ 168	$ 158
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Extended credit and standby letters of credit	$ 9,806	$ 9,285

COMMITMENTS, CREDIT RISK AND _4

COMMITMENTS, CREDIT RISK AND CONTINGENCIES - Additional Information (Detail) $ in Millions	Mar. 31, 2021USD ($)
Commitments and Contingencies Disclosure [Abstract]
Percentage of commitments to extend credit dependent upon the financial condition of the customers	74.60%
Allowance for credit losses on loan commitments that are not unconditionally cancellable	$ 13.5

STOCK INCENTIVE PLANS - Additio

STOCK INCENTIVE PLANS - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares available up to (in shares)	5,362,034
Common stock additional shares registered (in shares)			4,640,000
Unrecognized compensation expense	$ 10
Shares, options outstanding and exercisable (in shares)	182,747	231,646
Weighted average exercise price, options outstanding (in USD per share)	$ 8.86	$ 8.22
Intrinsic value of outstanding and exercisable stock options	$ 0.7
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of units issued, years	3 years
Restricted stock awards issued (in shares)	542,136	1,988,225
Unrecognized compensation expense	$ 10
Amount subject to accelerated vesting under Incentive Compensation Plan	1.2
Performance-based Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense	$ 3
Performance-based Units [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock awards issued (in shares)	325,284	571,932

STOCK INCENTIVE PLANS - Restric

STOCK INCENTIVE PLANS - Restricted Stock Units Activity (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, unvested units outstanding at end of period (in shares)	5,082,796
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, unvested units outstanding at beginning of period (in shares)	4,322,115	2,858,357
Shares, granted (in shares)	542,136	1,988,225
Net adjustment due to performance (in shares)	327,256	0
Shares, vested (in shares)	(142,687)	(1,717)
Shares, forfeited/expired (in shares)	(8,334)	(11,362)
Shares, dividend reinvestment (in shares)	42,310	39,865
Shares, unvested units outstanding at end of period (in shares)	5,082,796	4,873,368
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant price, invested units outstanding at beginning of period (in USD per share)	$ 9.46	$ 12.56
Weighted average grant price, granted (in USD per share)	12.61	6.95
Weighted average grant price, net adjusted due to performance (in USD per share)	11.84	0
Weighted average grant price, vested (in USD per share)	7.29	14.15
Weighted average grant price, forfeited/expired (in USD per share)	7.52	12.85
Weighted average grant price, dividend reinvestment (in USD per share)	13.43	8.57
Weighted average grant price, invested units outstanding at end of period (in USD per share)	$ 10.05	$ 10.23

STOCK INCENTIVE PLANS - Schedul

STOCK INCENTIVE PLANS - Schedule of Certain Information Related to Restricted Stock Units (Detail) - Restricted Stock [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 12	$ 8
Tax benefit related to stock-based compensation expense	3	2
Fair value of units vested	$ 1	$ 0

STOCK INCENTIVE PLANS - Compone

STOCK INCENTIVE PLANS - Components of Restricted Stock Units (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units (in shares) | shares	5,082,796
Unrecognized compensation expense	$ 10
Intrinsic value	$ 64
Weighted average remaining life (in years)	1 year 5 months 26 days
Service-Based Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units (in shares) | shares	3,076,326
Unrecognized compensation expense	$ 7
Intrinsic value	$ 39
Weighted average remaining life (in years)	1 year 7 months 20 days
Performance-based Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested restricted stock units (in shares) | shares	2,006,470
Unrecognized compensation expense	$ 3
Intrinsic value	$ 25
Weighted average remaining life (in years)	1 year 3 months 7 days

INCOME TAXES - Income Tax Expen

INCOME TAXES - Income Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Current income taxes: Federal taxes	$ 21	$ 7
Current income taxes: State taxes	2	2
Total current income taxes	23	9
Deferred income taxes: Federal taxes	(1)	2
Deferred income taxes: State taxes	0	0
Total deferred income taxes	(1)	2
Income taxes	$ 22	$ 11
Statutory tax rate	21.00%	21.00%
Effective tax rate	18.90%	18.80%

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Deferred tax assets	$ 56.1	$ 51

OTHER COMPREHENSIVE INCOME (Det

OTHER COMPREHENSIVE INCOME (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 4,959
Other comprehensive (loss) income before reclassifications	(16)
Amounts reclassified from AOCI	4
Net current period other comprehensive (loss) income	(12)
Balance at end of period	4,974
Unrealized Net Gains (Losses) on Debt Securities Available for Sale [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	65
Other comprehensive (loss) income before reclassifications	(21)
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	(21)
Balance at end of period	44
Unrealized Net Gains (Losses) on Derivative Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(40)
Other comprehensive (loss) income before reclassifications	4
Amounts reclassified from AOCI	4
Net current period other comprehensive (loss) income	8
Balance at end of period	(32)
Unrecognized Pension and Postretirement Obligations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(64)
Other comprehensive (loss) income before reclassifications	1
Amounts reclassified from AOCI	0
Net current period other comprehensive (loss) income	1
Balance at end of period	(63)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(39)
Balance at end of period	$ (51)

EARNINGS PER COMMON SHARE - Com

EARNINGS PER COMMON SHARE - Computation of Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income	$ 93	$ 47
Less: Preferred stock dividends	2	2
Net Income Available to Common Stockholders	$ 91	$ 45
Basic weighted average common shares outstanding (in shares)	320,975,209	324,247,710
Net effect of dilutive stock options, warrants and restricted stock (in shares)	3,769,650	1,797,472
Diluted weighted average common shares outstanding (in shares)	324,744,859	326,045,182
Earnings per common share:
Basic (in USD per share)	$ 0.28	$ 0.14
Diluted (in USD per share)	$ 0.28	$ 0.14

EARNINGS PER COMMON SHARE - Ave

EARNINGS PER COMMON SHARE - Average Shares Excluded from Earnings Per Common Share (Detail) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Average shares excluded from the diluted earnings per common share calculation (in shares)	0	450

CASH FLOW INFORMATION (Detail)

CASH FLOW INFORMATION (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Interest paid on deposits and other borrowings	$ 32	$ 75
Income taxes paid	5	0
Transfers of loans to other real estate owned	$ 0	$ 1

BUSINESS SEGMENTS - Additional

BUSINESS SEGMENTS - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2021Segment
Segment Reporting [Abstract]
Number of reportable segments	3

BUSINESS SEGMENTS - Financial I

BUSINESS SEGMENTS - Financial Information for Segments (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Interest income	$ 251	$ 306
Interest expense	28	74
Net Interest Income	223	232
Provision for credit losses	6	48
Non-interest income	83	69
Non-interest expense	182	192
Amortization of intangibles	3	3
Income tax expense (benefit)	22	11
Net income (loss)	93	47
Total assets	38,475	35,049	$ 37,354
Total intangibles	2,313	2,326
Operating Segments [Member] | Community Banking [Member]
Segment Reporting Information [Line Items]
Interest income	251	306
Interest expense	25	68
Net Interest Income	226	238
Provision for credit losses	6	48
Non-interest income	63	52
Non-interest expense	165	176
Amortization of intangibles	3	3
Income tax expense (benefit)	22	12
Net income (loss)	93	51
Total assets	38,360	34,933
Total intangibles	2,276	2,288
Operating Segments [Member] | Wealth Management [Member]
Segment Reporting Information [Line Items]
Interest income	0	0
Interest expense	0	0
Net Interest Income	0	0
Provision for credit losses	0	0
Non-interest income	15	13
Non-interest expense	10	10
Amortization of intangibles	0	0
Income tax expense (benefit)	1	1
Net income (loss)	4	2
Total assets	40	34
Total intangibles	9	9
Operating Segments [Member] | Insurance [Member]
Segment Reporting Information [Line Items]
Interest income	0	0
Interest expense	0	0
Net Interest Income	0	0
Provision for credit losses	0	0
Non-interest income	6	6
Non-interest expense	5	5
Amortization of intangibles	0	0
Income tax expense (benefit)	0	0
Net income (loss)	1	1
Total assets	34	36
Total intangibles	28	29
Parent and Other [Member]
Segment Reporting Information [Line Items]
Interest income	0	0
Interest expense	3	6
Net Interest Income	(3)	(6)
Provision for credit losses	0	0
Non-interest income	(1)	(2)
Non-interest expense	2	1
Amortization of intangibles	0	0
Income tax expense (benefit)	(1)	(2)
Net income (loss)	(5)	(7)
Total assets	41	46
Total intangibles	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Asset

FAIR VALUE MEASUREMENTS - Assets and Liabilities on Recurring Basis (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		$ 3,166	$ 3,463
Loans held for sale	[1]	165	144
Derivative assets		236	376
Derivative liabilities		59	40
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		100	600
US Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		175	172
U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		160	161
Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		1,263	1,124
Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		335	378
States of the U.S. and Political Subdivisions (municipals) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		28	32
Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		2	2
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		100	600
Derivative assets		0	0
Derivative liabilities		0	0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		3,066	2,863
Derivative assets		226	352
Derivative liabilities		58	40
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Derivative assets		10	24
Derivative liabilities		1	0
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		3,166	3,463
Loans held for sale		165	144
Derivative assets		236	376
Total assets measured at fair value on a recurring basis		3,567	3,983
Derivative liabilities		59	40
Total liabilities measured at fair value on a recurring basis		59	40
Fair Value, Recurring [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		100	600
Fair Value, Recurring [Member] | US Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		175	172
Fair Value, Recurring [Member] | U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		160	161
Fair Value, Recurring [Member] | Agency Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		1,103	994
Fair Value, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		1,263	1,124
Fair Value, Recurring [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		335	378
Fair Value, Recurring [Member] | States of the U.S. and Political Subdivisions (municipals) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		28	32
Fair Value, Recurring [Member] | Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		2	2
Fair Value, Recurring [Member] | Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		214	349
Fair Value, Recurring [Member] | Non Trading Account Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		22	27
Fair Value, Recurring [Member] | Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		58	37
Fair Value, Recurring [Member] | Not for Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		1	3
Fair Value, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		100	600
Loans held for sale		0	0
Derivative assets		0	0
Total assets measured at fair value on a recurring basis		100	600
Derivative liabilities		0	0
Total liabilities measured at fair value on a recurring basis		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		100	600
Fair Value, Recurring [Member] | Level 1 [Member] | US Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Agency Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | States of the U.S. and Political Subdivisions (municipals) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Non Trading Account Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0	0
Fair Value, Recurring [Member] | Level 1 [Member] | Not for Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0	0
Fair Value, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		3,066	2,863
Loans held for sale		165	144
Derivative assets		226	352
Total assets measured at fair value on a recurring basis		3,457	3,359
Derivative liabilities		58	40
Total liabilities measured at fair value on a recurring basis		58	40
Fair Value, Recurring [Member] | Level 2 [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 2 [Member] | US Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		175	172
Fair Value, Recurring [Member] | Level 2 [Member] | U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		160	161
Fair Value, Recurring [Member] | Level 2 [Member] | Agency Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		1,103	994
Fair Value, Recurring [Member] | Level 2 [Member] | Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		1,263	1,124
Fair Value, Recurring [Member] | Level 2 [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		335	378
Fair Value, Recurring [Member] | Level 2 [Member] | States of the U.S. and Political Subdivisions (municipals) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		28	32
Fair Value, Recurring [Member] | Level 2 [Member] | Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		2	2
Fair Value, Recurring [Member] | Level 2 [Member] | Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		214	349
Fair Value, Recurring [Member] | Level 2 [Member] | Non Trading Account Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		12	3
Fair Value, Recurring [Member] | Level 2 [Member] | Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		58	37
Fair Value, Recurring [Member] | Level 2 [Member] | Not for Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0	3
Fair Value, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Loans held for sale		0	0
Derivative assets		10	24
Total assets measured at fair value on a recurring basis		10	24
Derivative liabilities		1	0
Total liabilities measured at fair value on a recurring basis		1	0
Fair Value, Recurring [Member] | Level 3 [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | US Government Agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | U.S. Government-Sponsored Entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Agency Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Agency Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Commercial Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | States of the U.S. and Political Subdivisions (municipals) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Trading Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Non Trading Account Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		10	24
Fair Value, Recurring [Member] | Level 3 [Member] | Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0	0
Fair Value, Recurring [Member] | Level 3 [Member] | Not for Trading Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		$ 1	$ 0
[1]	Amount represents loans for which we have elected the fair value option. See Note 18.

FAIR VALUE MEASUREMENTS - Rollf

FAIR VALUE MEASUREMENTS - Rollforward on Recurring Basis (Detail) - Fair Value, Recurring [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 24	$ 3
Purchases, issuances, sales and settlements:
Issuances	10	24
Settlements	(24)	(3)
Balance at end of period	10	24
Interest Rate Lock Commitments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	24	3
Purchases, issuances, sales and settlements:
Issuances	10	24
Settlements	(24)	(3)
Balance at end of period	$ 10	$ 24

FAIR VALUE MEASUREMENTS - Addit

FAIR VALUE MEASUREMENTS - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value Measurements Disclosure [Line Items]
Transfer of equity security to non-marketable equity securities, included in other assets	$ 0	$ 0
Collateral dependent loans, allowance for credit loss	18,000,000
Provision for fair value measurements included in allowance for loan losses	6,800,000
Carrying amount of OREO	500,000
Written down of OREO	400,000
Loss from OREO included in earnings	100,000
Fair Value, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Collateral dependent loans carrying value	19,200,000
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Servicing asset	13,900,000
Valuation allowance for impairment of recognized servicing assets, additions (deductions) for expenses (recoveries)	4,800,000
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member] | Provision Expense [Member]
Fair Value Measurements Disclosure [Line Items]
Valuation allowance for impairment of recognized servicing assets, provision recovery	2,500,000
SBA-Guaranteed Loan Servicing [Member] | Fair Value, Nonrecurring [Member]
Fair Value Measurements Disclosure [Line Items]
Servicing asset	3,100,000
Valuation allowance for impairment of recognized servicing assets, additions (deductions) for expenses (recoveries)	900,000
Valuation allowance for impairment of recognized servicing assets, provision recovery	$ 200,000

FAIR VALUE MEASUREMENTS - Add_2

FAIR VALUE MEASUREMENTS - Additional Information on Non-Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	$ 0	$ 0
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	0	0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	43	39
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	14	45
Other real estate owned	0	3
Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	0	0
Other real estate owned	0	0
Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	0	0
Other real estate owned	0	0
Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent loans	14	45
Other real estate owned	0	3
Mortgage Servicing Rights [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	40.2	35.6	$ 34.9	$ 45
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	14	36
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	0	0
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	0	0
Mortgage Servicing Rights [Member] | Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	14	36
SBA-Guaranteed Loan Servicing [Member] | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	3	3
SBA-Guaranteed Loan Servicing [Member] | Fair Value, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	0	0
SBA-Guaranteed Loan Servicing [Member] | Fair Value, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	0	0
SBA-Guaranteed Loan Servicing [Member] | Fair Value, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other asset	$ 3	$ 3

FAIR VALUE MEASUREMENTS - Finan

FAIR VALUE MEASUREMENTS - Financial Instruments (Detail) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 2,668	$ 1,383
Debt securities available for sale	3,166	3,463
Securities held to maturity	3,043	2,868
Securities held to maturity, fair value	3,114	2,973
Net loans and leases	25,170	25,096
Derivative assets	236	376
Deposits	30,354	29,122
Short-term borrowings	1,687	1,804
Long-term borrowings	1,091	1,095
Long-term borrowings, fair value	547
Derivative liabilities	59	40
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	2,668	1,383
Debt securities available for sale	3,166	3,463
Securities held to maturity	3,043	2,868
Net loans and leases	25,355	25,250
Loan servicing rights	42	39
Derivative assets	236	376
Accrued interest receivable	89	90
Deposits	30,354	29,122
Short-term borrowings	1,687	1,804
Long-term borrowings	1,091	1,095
Derivative liabilities	59	40
Accrued interest payable	9	13
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	2,668	1,383
Debt securities available for sale	3,166	3,463
Securities held to maturity, fair value	3,114	2,973
Net loans and leases, fair value	24,938	25,012
Loan servicing rights, fair value	43	39
Derivative assets	236	376
Accrued interest receivable	89	90
Deposits, fair value	30,376	29,158
Short-term borrowings, fair value	1,688	1,809
Long-term borrowings, fair value	1,088	1,068
Derivative liabilities	59	40
Accrued interest payable	9	13
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	2,668	1,383
Debt securities available for sale	100	600
Securities held to maturity, fair value	1	0
Net loans and leases, fair value	0	0
Loan servicing rights, fair value	0	0
Derivative assets	0	0
Accrued interest receivable	89	90
Deposits, fair value	26,970	25,460
Short-term borrowings, fair value	1,688	1,809
Long-term borrowings, fair value	0	0
Derivative liabilities	0	0
Accrued interest payable	9	13
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	0	0
Debt securities available for sale	3,066	2,863
Securities held to maturity, fair value	3,113	2,973
Net loans and leases, fair value	165	144
Loan servicing rights, fair value	0	0
Derivative assets	226	352
Accrued interest receivable	0	0
Deposits, fair value	3,406	3,698
Short-term borrowings, fair value	0	0
Long-term borrowings, fair value	0	0
Derivative liabilities	58	40
Accrued interest payable	0	0
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents, fair value	0	0
Debt securities available for sale	0	0
Securities held to maturity, fair value	0	0
Net loans and leases, fair value	24,773	24,868
Loan servicing rights, fair value	43	39
Derivative assets	10	24
Accrued interest receivable	0	0
Deposits, fair value	0	0
Short-term borrowings, fair value	0	0
Long-term borrowings, fair value	1,088	1,068
Derivative liabilities	1	0
Accrued interest payable	$ 0	$ 0