Zions Bancorporation, National Association (ZION) 10-K 25 Feb 21 2020 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 08, 2021	Jun. 30, 2020
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-12307
Entity Registrant Name	ZIONS BANCORPORATION, NATIONAL ASSOCIATION
Entity Incorporation, State or Country Code	X1
Entity Tax Identification Number	87-0189025
Entity Address, Address Line One	One South Main
Entity Address, City or Town	Salt Lake City,
Entity Address, State or Province	UT
Entity Address, Postal Zip Code	84133-1109
City Area Code	801
Local Phone Number	844-7637
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 5,470,950,404
Entity Common Stock, Shares Outstanding		164,214,100
Documents Incorporated by Reference	Documents Incorporated by Reference: Part III of this Annual Report on Form 10-K incorporates by reference specified portions of Zions Bancorporation, National Association's Proxy Statement for its 2021 Annual Meeting of Shareholders, which the registrant anticipates will be filed with the Securities and Exchange Commission approximately March 18, 2021.
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0000109380
Common stock | The NASDAQ Stock Market LLC
Document Information [Line Items]
Title of 12(b) Security	Common Stock, par value $0.001
Trading Symbol	ZION
Security Exchange Name	NASDAQ
Series A Floating-Rate Non-Cumulative Perpetual Preferred Stock | The NASDAQ Stock Market LLC
Document Information [Line Items]
Title of 12(b) Security	Series A Floating-Rate Non-Cumulative Perpetual Preferred Stock
Trading Symbol	ZIONP
Security Exchange Name	NASDAQ
Series G Fixed/Floating-Rate Non-Cumulative Perpetual Preferred Stock | The NASDAQ Stock Market LLC
Document Information [Line Items]
Title of 12(b) Security	Series G Fixed/Floating-Rate Non-Cumulative Perpetual Preferred Stock
Trading Symbol	ZIONO
Security Exchange Name	NASDAQ
Series H 5.75% Non-Cumulative Perpetual Preferred Stock | The NASDAQ Stock Market LLC
Document Information [Line Items]
Title of 12(b) Security	Series H 5.75% Non-Cumulative Perpetual Preferred Stock
Trading Symbol	ZIONN
Security Exchange Name	NASDAQ
6.95% Fixed-to-Floating Rate Subordinated Notes due September 15, 2028 | The NASDAQ Stock Market LLC
Document Information [Line Items]
Title of 12(b) Security	6.95% Fixed-to-Floating Rate Subordinated Notes due September 15, 2028
Trading Symbol	ZIONL
Security Exchange Name	NASDAQ

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Cash and due from banks	$ 543	$ 705
Money market investments:
Interest-bearing deposits	1,074	743
Federal funds sold and security resell agreements	5,765	484
Investment securities:
Held-to-maturity, at amortized cost	636	592
Available-for-sale, at fair value	15,731	13,725
Trading account, at fair value	266	182
Total investment securities	16,633	14,499
Loans held for sale	81	129
Loans, net of allowance
Loans and leases, net of unearned income and fees	53,476	48,709
Less allowance for loan losses	777	495
Loans, net of allowance	52,699	48,214
Other noninterest-bearing investments	817	898
Premises, equipment and software, net	1,209	1,142
Goodwill and intangibles	1,016	1,014
Other real estate owned	4	8
Other assets	1,638	1,336
Total assets	81,479	69,172
LIABILITIES AND SHAREHOLDERS’ EQUITY
Noninterest-bearing demand	32,494	23,576
Interest-bearing:
Savings and money market	34,571	28,790
Time	2,588	4,719
Total deposits	69,653	57,085
Federal funds and other short-term borrowings	1,572	2,053
Long-term debt	1,336	1,723
Reserve for unfunded lending commitments	58	59
Other liabilities	974	899
Total liabilities	73,593	61,819
Shareholders’ equity:
Preferred stock, without par value; authorized 4,400 shares	566	566
Common stock ($0.001 par value; authorized 350,000 shares; issued and outstanding 164,090 and 165,057 shares and additional paid-in capital	2,686	2,735
Retained earnings	4,309	4,009
Accumulated other comprehensive income	325	43
Total shareholders’ equity	7,886	7,353
Total liabilities and shareholders’ equity	$ 81,479	$ 69,172

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Investment securities:
Held-to-maturity investment securities	$ 640	$ 597
Shareholders’ equity:
Preferred stock, authorized shares (in shares)	4,400,000	4,400,000
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized shares (in shares)	350,000,000	350,000,000
Common stock, issued shares (in shares)	164,090,000	165,057,000
Common stock, outstanding shares (in shares)	164,090,000	165,057,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest income:
Interest and fees on loans	$ 2,050	$ 2,289	$ 2,102
Interest on money market investments	14	32	29
Interest on securities	304	362	350
Total interest income	2,368	2,683	2,481
Interest expense:
Interest on deposits	105	254	135
Interest on short- and long-term borrowings	47	157	116
Total interest expense	152	411	251
Net interest income	2,216	2,272	2,230
Provision for loan losses	385	37	(39)
Provision for unfunded lending commitments	29	2	(1)
Total provision for credit losses	414	39	(40)
Net interest income after provision for credit losses	1,802	2,233	2,270
Noninterest income:
Commercial account fees	125	121	122
Card fees	82	92	94
Retail and business banking fees	68	78	78
Loan-related fees and income	109	75	74
Capital markets and foreign exchange fees	77	78	58
Wealth management and trust fees	62	60	55
Other customer-related fees	26	21	27
Customer-related fees	549	525	508
Fair value and nonhedge derivative loss	(6)	(9)	(1)
Dividends and other income	24	43	44
Securities gains, net	7	3	1
Total noninterest income	574	562	552
Noninterest expense:
Salaries and employee benefits	1,087	1,141	1,070
Occupancy, net	130	133	132
Furniture, equipment and software, net	127	135	126
Other real estate expense, net	1	(3)	1
Credit-related expense	22	20	25
Professional and legal services	52	47	52
Advertising	19	19	26
FDIC premiums	25	25	50
Other	241	225	197
Total noninterest expense	1,704	1,742	1,679
Income before income taxes	672	1,053	1,143
Income taxes	133	237	259
Net income	539	816	884
Preferred stock dividends	(34)	(34)	(34)
Preferred stock redemption	0	0	0
Net earnings applicable to common shareholders	$ 505	$ 782	$ 850
Weighted average common shares outstanding during the year:
Basic shares (in shares)	163,737	175,984	193,589
Diluted shares (in shares)	165,613	186,504	206,501
Net earnings per common share:
Basic (in dollars per share)	$ 3.06	$ 4.41	$ 4.36
Diluted (in dollars per share)	$ 3.02	$ 4.16	$ 4.08

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 539	$ 816	$ 884
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) on investment securities	229	257	(113)
Net unrealized gains (losses) on other noninterest-bearing investments	1	(9)	2
Net unrealized holding gains (losses) on derivative instruments	76	33	(4)
Reclassification adjustment for decrease (increase) in interest income recognized in earnings on derivative instruments	(36)	5	3
Pension and postretirement	12	7	1
Other comprehensive income (loss)	282	293	(111)
Comprehensive income	$ 821	$ 1,109	$ 773

Consolidated Statements of Chan

Consolidated Statements of Changes in Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Preferred stock	Common stock	Accumulated paid-in capital	Retained earnings	Retained earningsCumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive income (loss)
Beginning balance at Dec. 31, 2017	$ 7,679	$ 1	$ 566	$ 4,445	$ 0	$ 2,807	$ 1	$ (139)
Beginning balance (in shares) at Dec. 31, 2017				197,532
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	884					884
Merger of Bank Holding Company into Bank				$ (4,052)	4,052
Other comprehensive income, net of tax	(111)							(111)
Bank common stock repurchased (in shares)				(12,984)
Bank common stock repurchased	(672)			$ (422)	(250)
Net shares issued from stock warrant exercises (in shares)				1,770
Net activity under employee plans and related tax benefits (in shares)				1,236
Net activity under employee plans and related tax benefits	33			$ 29	4
Dividends on preferred stock	(34)					(34)
Dividends on common stock	(202)					(202)
Ending balance at Dec. 31, 2018	$ 7,578	(3)	566	$ 0	3,806	3,456	(3)	(250)
Ending balance (in shares) at Dec. 31, 2018				187,554
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201708Member
Net income	$ 816					816
Other comprehensive income, net of tax	$ 293							293
Bank common stock repurchased (in shares)	(23,500)			(23,531)
Bank common stock repurchased	$ (1,102)				(1,102)
Net shares issued from stock warrant exercises (in shares)				8
Net activity under employee plans and related tax benefits (in shares)				1,026
Net activity under employee plans and related tax benefits	31				31
Dividends on preferred stock	(34)					(34)
Dividends on common stock	(226)					(226)
Ending balance at Dec. 31, 2019	$ 7,353	$ 20	566	$ 0	2,735	4,009	$ 20	43
Ending balance (in shares) at Dec. 31, 2019	165,057			165,057
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Net income	$ 539					539
Other comprehensive income, net of tax	$ 282							282
Bank common stock repurchased (in shares)	(1,700)			(1,686)
Bank common stock repurchased	$ (76)				(76)
Net shares issued from stock warrant exercises (in shares)				1
Net activity under employee plans and related tax benefits (in shares)				718
Net activity under employee plans and related tax benefits	27				27
Dividends on preferred stock	(34)					(34)
Dividends on common stock	(225)					(225)
Ending balance at Dec. 31, 2020	$ 7,886		$ 566	$ 0	$ 2,686	$ 4,309		$ 325
Ending balance (in shares) at Dec. 31, 2020	164,090			164,090

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends on common stock (in dollars per share)	$ 1.36	$ 1.28	$ 1.04

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 539	$ 816	$ 884
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for credit losses	414	39	(40)
Depreciation and amortization	86	188	193
Share-based compensation	26	27	26
Deferred income tax benefit	(58)	(2)	0
Net decrease (increase) in trading securities	(83)	(76)	42
Net decrease (increase) in loans held for sale	(10)	(84)	9
Change in other liabilities	57	(14)	74
Change in other assets	(223)	(179)	14
Other, net	(29)	(18)	(26)
Net cash provided by operating activities	719	697	1,176
CASH FLOWS FROM INVESTING ACTIVITIES
Net decrease (increase) in money market investments	(5,611)	852	(784)
Proceeds from maturities and paydowns of investment securities held-to-maturity	386	391	361
Purchases of investment securities held-to-maturity	(430)	(209)	(365)
Proceeds from sales, maturities, and paydowns of investment securities available-for-sale	4,339	3,105	3,061
Purchases of investment securities available-for-sale	(6,151)	(1,864)	(2,927)
Net change in loans and leases	(4,687)	(1,957)	(1,943)
Purchases and sales of other noninterest-bearing investments	79	172	14
Purchases of premises and equipment	(171)	(117)	(129)
Other, net	42	2	6
Net cash provided by (used in) investing activities	(12,204)	375	(2,706)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase in deposits	12,568	2,984	1,484
Net change in short-term funds borrowed	(481)	(3,600)	2,677
Repayments of debt over 90 days and up to one year	0	0	(2,000)
Repayments of long-term debt	(429)	0	(162)
Proceeds from the issuance of long-term debt	0	992	497
Bank common stock repurchased	(76)	(1,102)	(672)
Proceeds from the issuance of common stock	8	14	20
Dividends paid on common and preferred stock	(259)	(260)	(236)
Other, net	(8)	(9)	(12)
Net cash provided by (used in) financing activities	11,323	(981)	1,596
Net increase (decrease) in cash and due from banks	(162)	91	66
Cash and due from banks at beginning of year	705	614	548
Cash and due from banks at end of year	543	705	614
Cash paid for interest	195	401	237
Net cash paid for income taxes	169	233	207
Noncash activities are summarized as follows:
Loans held for investment transferred to other real estate owned	4	12	8
Loans held for investment reclassified to loans held for sale, net	$ (11)	$ 85	$ 111

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Business Zions Bancorporation, National Association and its subsidiaries (collectively “Zions Bancorporation, N.A.,” “the Bank,” “we,” “our,” “us”) together comprise a bank headquartered in Salt Lake City, Utah. We provide a wide range of banking products and related services in 11 Western and Southwestern states through seven separately managed affiliates, as follows: Zions Bank in Utah, Idaho and Wyoming; California Bank & Trust (“CB&T”); Amegy Bank (“Amegy”) in Texas; National Bank of Arizona (“NBAZ”); Nevada State Bank (“NSB”); Vectra Bank Colorado (“Vectra”) in Colorado and New Mexico; and The Commerce Bank of Washington (“TCBW”) which operates under that name in Washington and under The Commerce Bank of Oregon (“TCBO”) in Oregon. Basis of Financial Statement Presentation and Principles of Consolidation The consolidated financial statements include our accounts and those of our majority-owned, consolidated subsidiaries. Unconsolidated investments where we have the ability to exercise significant influence over the operating and financial policies of the respective investee are accounted for using the equity method of accounting. All significant intercompany accounts and transactions have been eliminated in consolidation. Assets held in an agency or fiduciary capacity are not included in the Consolidated Financial Statements. The consolidated financial statements have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“GAAP”) and prevailing practices within the financial services industry. References to GAAP, including standards promulgated by the Financial Accounting Standards Board (“FASB”), are made according to sections of the Accounting Standards Codification (“ASC”). Changes to the ASC are made with Accounting Standards Updates (“ASU”) that include consensus issues of the Emerging Issues Task Force. In certain cases, ASUs are issued jointly with International Financial Reporting Standards. In preparing the consolidated financial statements, we are required to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Certain prior year amounts have been reclassified to conform with the current year presentation. These reclassifications did not affect net income or shareholders’ equity. Variable Interest Entities A variable interest entity (“VIE”) is consolidated when a company is the primary beneficiary of the VIE. Current accounting guidance requires continuous analysis on a qualitative rather than a quantitative basis to determine the primary beneficiary of a VIE. At the commencement of our involvement, and periodically thereafter, we consider our consolidation conclusions for all entities with which we are involved. As of December 31, 2020, and 2019, we have no VIEs that have been consolidated in our financial statements. Statement of Cash Flows For purposes of presentation in the consolidated statements of cash flows, “cash and cash equivalents” are defined as those amounts included in cash and due from banks in the consolidated balance sheets. Fair Value Estimates We measure many of our assets and liabilities on a fair value basis. Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. To improve consistency and comparability in fair value measurements, GAAP has established a hierarchy to prioritize the valuation inputs among three levels. We prioritize quoted prices in active markets and minimize reliance on unobservable inputs when possible. When observable market prices are not available, fair value is estimated using modeling techniques such as discounted cash flow analysis. These modeling techniques use assumptions that market participants would consider in pricing the asset or the liability — including assumptions about the risk inherent in a particular valuation technique — the effect of a restriction on the sale or use of an asset, the life of the asset and applicable growth rate, the risk of nonperformance, and other related assumptions. Changes in market conditions may reduce the availability of quoted prices or observable data. When market data is not available, we use valuation techniques requiring professional judgment to estimate the appropriate fair value. See Note 3 of the “Notes to Consolidated Financial Statements” for further information regarding the use of fair value estimates. Security Resell Agreements Security resell agreements represent overnight and term agreements with the majority maturing within 30 days. Due to increased cash reserves and in order to increase yield, we have extended the maturity of some security resell agreements beyond 30 days. As of December 31, 2020, 28% of all security resell agreements have a maturity beyond 30 days but none greater than 50 days. These agreements are generally treated as collateralized financing transactions and are carried at amounts at which the securities were acquired plus accrued interest. Either we, or in some instances third-parties on our behalf, take possession of the underlying securities. The fair value of such securities is monitored throughout the contract term to ensure that asset values remain sufficient to protect against counterparty default. We are permitted by contract to sell or repledge certain securities that we accept as collateral for security resell agreements. If sold, our obligation to return the collateral is recorded as “securities sold, not yet purchased” and included as a liability in “Federal funds and other short-term borrowings.” At December 31, 2020, we held $5.7 billion of securities for which we were permitted by contract to sell or repledge. Security resell agreements averaged $2.1 billion during 2020, and the maximum amount outstanding at any month-end during 2020 was $6.4 billion. Investment Securities We classify our investment securities according to their purpose and holding period. Gains or losses on the sale of securities are recognized using the specific identification method and recorded in noninterest income. Held-to-maturity (“HTM”) debt securities are carried at amortized cost with purchase discounts or premiums accreted or amortized into interest income over the contractual life of the security. We have the intent and ability to hold such securities until maturity. For HTM securities, the ACL is assessed consistent with the approach described in Note 6 for loans carried at amortized cost. Available-for-sale (“AFS”) securities are stated at fair value and generally consist of debt securities held for investment. Unrealized gains and losses of AFS securities, after applicable taxes, are recorded as a component of other comprehensive income (“OCI”). AFS securities in an unrealized loss position are formally reviewed on a quarterly basis for the presence of impairment. If we have an intent to sell an identified security, or it is more likely than not we will be required to sell the security before recovery of its amortized cost basis, then we recognize an impairment equal to any existing allowance written off against the security. If we do not have the intent to sell a security, and it is more likely than not that we will not be required to sell a security prior to recovery of its amortized cost basis, then we determine whether there is any impairment attributable to credit-related factors. The process, methodology, and factors considered to evaluate securities for impairment are described further in Note 5. Trading securities are stated at fair value and consist of securities acquired for short-term appreciation or other trading purposes. Realized and unrealized gains and losses are recorded in trading income, which is included in “Capital Markets and Foreign Exchange.” The fair values of investment securities, as estimated under current accounting guidance, are described in Note 3. Leases As a lessee, when we enter a lease contract, we classify and account for the lease as either a finance lease or an operating lease, depending on the terms and conditions of the lease. A finance lease is recorded as an asset and a liability, and the asset is generally depreciated over the lease term. The lease liability is reduced as lease payments are made. An operating lease is recorded as a right-of-use (“ROU”) asset and operating lease liability. These balance sheet items are reduced as lease payments are made. Lease payments are expensed over the lease term; they are recorded as rent expense and are recognized on a straight-line basis. Lease-related assets are reviewed for impairment on an on-going basis. The lease term is the non-cancelable period that we have the right to use the leased asset. This term begins on the commencement date of the lease and incorporates options to extend or renew the lease when it is reasonably certain that we will exercise these options. Loans Loans are reported at the principal amount outstanding, net of unearned income, unamortized purchase premiums and discounts, and net deferred loan fees and costs, which are amortized to interest income over the life of the loan using the interest method. Interest income is recognized on an accrual basis. At the time of origination, we determine whether loans will be held for investment or held for sale. We may subsequently change our intent to hold loans for investment and reclassify them as held for sale. Loans held for sale are carried at the lower of aggregate cost or fair value. A valuation allowance is recorded when cost exceeds fair value based on reviews at the time of reclassification and periodically thereafter. Gains and losses are recorded in noninterest income based on the difference between sales proceeds and carrying value. We evaluate loans throughout their lives for signs of credit deterioration, which may impact the loan’s status, and potentially impact our accounting for that loan. Loan status categories include past due as to contractual payments, nonaccrual, and restructured, including troubled debt restructurings (“TDRs”). Our accounting policies for these loan statuses and our estimation of the related allowance for loan and lease losses (“ALLL”) are described further in Note 6. In the ordinary course of business, we transfer portions of loans under participation agreements to manage credit risk and our portfolio concentration. We evaluate the loan participations to determine if they meet the appropriate accounting guidance to qualify as sales. Certain purchased loans require separate accounting procedures that are also described in Note 6. Allowance for Credit Losses The allowance for credit losses (“ACL”) includes the ALLL and the reserve for unfunded lending commitments (“RULC”). For periods prior to 2020, the ALLL represented management’s estimate of probable losses believed to be inherent in the loan portfolio at that time, and the RULC was estimated using the same procedures and methodologies as for the ALLL, in addition to assumptions regarding the probability and amount of unfunded commitments being drawn. On January 1, 2020, we adopted ASU 2016-13, Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and its subsequent updates, often referred to as the Current Expected Credit Loss (“CECL”) model. CECL changes how the ACL is measured for loans and for additional financial assets, including HTM securities. Under CECL, the ACL will represent our estimate of current expected credit losses over the contractual term of the loan and lease portfolio and unfunded lending commitments as of the balance sheet date. The ACL for debt securities is estimated separately from loans. Further discussion of our estimation process for the ACL is included in Note 6. Other Noninterest-bearing Investments These investments include investments in private equity funds — referred to in this document as private equity investments (“PEIs”) — venture capital securities, securities acquired for various debt and regulatory requirements, bank-owned life insurance (“BOLI”), and certain other noninterest-bearing investments. See further discussion in Note 3. Certain PEIs and venture capital securities are accounted for under the equity method and some are reported at fair value. Changes in fair value and gains and losses from sales are recognized in noninterest income. The values assigned to the securities where no market quotations exist are based upon available information and may not necessarily represent amounts that will ultimately be realized. Such estimated amounts depend on future circumstances and will not be realized until the individual securities are liquidated. BOLI is accounted for at fair value based on the cash surrender values (“CSVs”) of the general account insurance policies. A third-party service provides these values. Other PEIs, and those acquired for various debt and regulatory requirements, are accounted for at cost less impairment (if any), plus or minus observable price changes from an identical or similar investment of the same issuer, with such changes recognized in income. Periodic reviews are conducted for impairment by comparing carrying values with estimates of fair value determined according to the previous discussion. Premises, Equipment and Software, Net Premises, equipment, and software are stated at cost, net of accumulated depreciation and amortization. Depreciation, computed primarily on the straight-line method, is charged to operations over the estimated useful lives of the properties, generally 25 to 40 years for buildings, three three to 10 years for software, including capitalized costs related to our technology initiatives. Leasehold improvements are amortized over the terms of the respective leases or the estimated useful lives of the improvements (including any extension options that are reasonably certain to be exercised), whichever is shorter. Premises, equipment and software are evaluated for impairment on a periodic basis. Goodwill and Identifiable Intangible Assets Goodwill and intangible assets deemed to have indefinite lives are not amortized. We subject these assets to annual specified impairment tests as of the beginning of the fourth quarter and more frequently if changing conditions warrant. Business Combinations Business combinations are accounted for under the acquisition method of accounting. Upon initially obtaining control, we recognize 100% of all acquired assets and all assumed liabilities, regardless of the percentage owned. The assets and liabilities are recorded at their estimated fair values, with goodwill being recorded when such fair values are less than the cost of acquisition. Certain transaction and restructuring costs are expensed as incurred. Changes to estimated fair values from a business combination are recognized as an adjustment to goodwill over the measurement period, which cannot exceed one year from the acquisition date. Results of operations of the acquired business are included in our statement of income from the date of acquisition. Other Real Estate Owned Other real estate owned (“OREO”) consists principally of commercial and residential real estate obtained in partial or total satisfaction of loan obligations. Amounts are recorded initially at fair value (less any selling costs) based on property appraisals at the time of transfer and subsequently at the lower of cost or fair value (less any selling costs). Derivative Instruments We use derivative instruments — including interest rate swaps and purchased and sold options such as floors and basis swaps—as part of our overall interest rate risk management strategy. Derivatives are an important tool used in managing our overall asset and liability sensitivities to remain within management’s stated interest rate risk thresholds. Their use allows us to adjust and align our naturally occurring mix of fixed and floating-rate assets and liabilities to manage interest income volatility by synthetically converting variable-rate assets to fixed-rate, or synthetically converting fixed-rate funding instruments to floating-rates. We also execute both interest rate and short-term foreign currency derivative instruments with our commercial banking customers to facilitate their risk management strategies. These derivatives are immediately hedged by offsetting derivatives with third-parties such that we minimize our net risk exposure as a result of such transactions. We record all derivatives at fair value in the balance sheet as either other assets or other liabilities. The accounting for the change in value of a derivative depends on whether or not the transaction has been designated and qualifies for hedge accounting. Derivatives that are not designated as hedges are reported and measured at fair value through earnings. See Note 7 for more information. Derivatives in Designated Accounting Hedge We apply hedge accounting to certain derivatives executed for risk management purposes, primarily interest rate risk. To qualify for hedge accounting, a derivative must be highly effective at reducing the risk associated with the exposure being hedged and the hedging relationship must be formally documented. We primarily use regression analysis to assess the effectiveness of each hedging relationship, unless the hedge qualifies for other methods of assessing effectiveness (e.g., shortcut or critical terms match), both at inception and on an ongoing basis. We designate derivatives as fair value and cash flow hedges for accounting purposes and these hedges can be a significant aspect of our overall interest risk sensitivity management. We may add additional hedging strategies and apply hedge accounting to the strategies as it deems necessary. See Note 7 for more information regarding the accounting for derivatives designated as hedging instruments. Commitments and Letters of Credit In the ordinary course of business, we enter into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the ALLL. The RULC is presented separately in the balance sheet. Revenue Recognition Service charges and fees on deposit accounts are recognized in accordance with published deposit account agreements for customer accounts or contractual agreements for commercial accounts. Other service charges, commissions, and fees include interchange fees, bank services, and other fees, which are generally recognized at the time of transaction or as the services are performed. Share-based Compensation Share-based compensation generally includes grants of stock options, restricted stock, restricted stock units (“RSUs”), and other awards to employees and nonemployee directors. We recognize compensation expense in the statement of income based on the grant-date value of the associated share-based awards. See further discussion in Note 19. Income Taxes Deferred tax assets (“DTAs”) and liabilities (“DTLs”) are determined based on temporary differences between financial statement asset and liability amounts and their respective tax basis and are measured using enacted tax laws and rates. The effect on DTAs and DTLs of a change in tax rates is recognized in income in the period that includes the enactment date. DTAs are recognized subject to management’s judgment that realization is more likely than not. Unrecognized tax benefits for uncertain tax positions relate primarily to tax credits on technology initiatives. See further discussion in Note 20. Net Earnings Per Common Share Net earnings per common share is based on net earnings applicable to common shareholders, which is net of preferred stock dividends. Basic net earnings per common share is based on the weighted average outstanding common shares during each year. Unvested share-based awards with rights to receive nonforfeitable dividends are considered participating securities and included in the computation of basic earnings per share. Diluted net earnings per common share is based on the weighted average outstanding common shares during each year, including common stock equivalents. Stock options, restricted stock, RSUs, and stock warrants are converted to common stock equivalents using the more dilutive of the treasury stock method or the two-class method. Diluted net earnings per common share excludes common stock equivalents whose effect is antidilutive. See further discussion in Note 21.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS Accounting Standard Updates Description Date of adoption Effect on the financial statements or other significant matters Updates adopted during 2020 ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting As part of reference rate reform, the London Interbank Offered Rate (“LIBOR ” ) is expected to be discontinued by June 30, 2023 and is being replaced by observable or transaction-based alternative reference rates. This ASU addresses certain operational accounting concerns of modifying contracts such as debt, lease, and derivative agreements that reference LIBOR, or another rate, that is expected to be discontinued due to reference rate reform. The ASU provides temporary optional expedients and exceptions to the accounting requirements for contract modifications for contracts that reference LIBOR. This ASU also provides for a one-time election to sell or transfer to available-for-sale or trading certain qualifying held-to-maturity (“HTM ” ) debt securities. Additionally, this guidance provides various optional expedients for hedging relationships affected by reference rate reform. April 1, 2020 We adopted ASU 2020-04 on April 1, 2020; the impact upon adoption was not significant as no practical expedients were applied in the current period, but will be applied in future periods. ASU 2016-13, Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments and subsequent related ASUs This ASU, and subsequent updates, significantly changes how entities will measure credit losses for virtually all financial assets and certain other instruments that are not measured at fair value through net income that have the contractual right to receive cash. The update replaces the “incurred loss” approach with a current expected credit loss (“CECL ” ) model for instruments such as loans and HTM securities that are measured at amortized cost. The ASU requires credit losses relating to available-for sale (“AFS”) debt securities to be recorded through an allowance for credit loss (“ACL”) rather than a reduction of the carrying amount and replaces the historically required other-than-temporary impairment (“OTTI”) analysis. It also changes the accounting for purchased credit-impaired debt securities and loans. The ASU retains many of the current disclosure requirements in U.S. GAAP and expands other disclosure requirements. The new guidance is effective for calendar year-end public companies beginning January 1, 2020. January 1, 2020 We adopted ASU 2016-13 and its subsequent updates on January 1, 2020; the impact upon adoption was an after-tax increase to retained earnings of approximately $20 million. Accounting Standard Updates Description Date of adoption Effect on the financial statements or other significant matters Updates adopted during 2020 ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This ASU removes the requirements in step two of the current goodwill impairment model, eliminating the requirement to calculate and compare the implied fair value of the reporting entity with the carrying amount of that entity, including goodwill, to measure any impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount of goodwill over its implied fair value of goodwill (i.e., measure the charge based on step one of the current guidance). January 1, 2020 We adopted ASU 2017-04 on January 1, 2020; the impact upon adoption was not significant. The transition and adoption provisions were applied prospectively.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE	FAIR VALUE Fair Value Measurement Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. To measure fair value, a hierarchy has been established that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. This hierarchy uses the following three levels of inputs to measure the fair value of assets and liabilities: Level 1 — Quoted prices in active markets for identical assets or liabilities in active markets that we have the ability to access; Level 2 — Observable inputs other than Level 1, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in less active markets, observable inputs other than quoted prices that are used in the valuation of an asset or liability, and inputs that are derived principally from or corroborated by observable market data by correlation or other means; and Level 3 — Unobservable inputs supported by little or no market activity for financial instruments whose value is determined by pricing models, discounted cash flow methodologies or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. The level in the fair value hierarchy within which the fair value measurement is classified is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Market activity is presumed to be orderly in the absence of evidence of forced or disorderly sales, although such sales may still be indicative of fair value. Applicable accounting guidance precludes the use of blockage factors or liquidity adjustments due to the quantity of securities held by an entity. We use fair value to measure certain assets and liabilities on a recurring basis when fair value is the primary measure for accounting. Fair value is used on a nonrecurring basis to measure certain assets when adjusting carrying values, such as the application of lower of cost or fair value accounting, including recognition of impairment on assets. Fair value is also used when providing required disclosures for certain financial instruments. Fair Value Policies and Procedures We have various policies, processes, and controls in place to ensure that fair values are reasonably developed, reviewed, and approved for use. These include a Securities Valuation Committee, comprised of executive management, that reviews and approves on a quarterly basis the key components of fair value estimation, including critical valuation assumptions for Level 3 modeling. A Model Risk Management Group conducts model validations, including internal models, and sets policies and procedures for revalidation, including the timing of revalidation. Third-party Service Providers We use a third party pricing service to measure fair value for approximately 95% of our AFS Level 2 securities. Fair value measurements for other AFS Level 2 securities generally use certain inputs corroborated by market data and include standard discounted cash flow analysis. For Level 2 securities, the third-party pricing service provides documentation on an ongoing basis that presents market corroborative data, including detailed pricing information and market reference data. The documentation includes benchmark yields, reported trades, broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data, including information from the vendor trading platform. We review, test, and validate this information as appropriate. Absent observable trade data, we do not adjust prices from our third-party sources. The following describes the hierarchy designations, valuation methodologies and key inputs to measure fair value on a recurring basis for designated financial instruments: Available-for-Sale U.S. Treasury, Agencies and Corporations U.S. Treasury securities are measured under Level 1 using quoted market prices when available. U.S. agencies and corporations are measured under Level 2 generally using the previously mentioned third-party pricing service. Municipal Securities Municipal securities are measured under Level 2 using the third-party pricing service. Money Market Mutual Funds and Other Money market mutual funds and other securities are measured under Level 1 or Level 2. For Level 1, quoted market prices are used which may include net asset values (“NAVs”) or their equivalents. Level 2 valuations generally use quoted prices for similar securities. Trading Account Securities in the trading account are generally measured under Level 2 using third-party pricing service providers as described previously. Held-to-Maturity HTM securities are carried at amortized cost, but for disclosure purposes are measured at fair value using a third-party pricing service or an internal model. The internal model utilizes observable market yields as inputs. Bank-owned Life Insurance BOLI is measured under Level 2 according to CSVs of the insurance policies that are provided by a third-party service. Nearly all policies are general account policies with CSVs based on our claims on the assets of the insurance companies. The insurance companies’ investments include predominantly fixed-income securities consisting of investment-grade corporate bonds and various types of mortgage instruments. Management regularly reviews its BOLI investment performance, including concentrations among insurance providers. Private Equity Investments PEIs are generally measured under Level 3. The majority of these PEIs are held in our Small Business Investment Company (“SBIC”) and are early-stage venture investments. The fair value measurements of these investments are reviewed at least on a quarterly basis, including whenever a new round of financing occurs. Certain of these investments may be measured using multiples of operating performance. The fair value measurements of PEIs are reviewed on a quarterly basis by the Securities Valuation Committee. The Equity Investments Committee, consisting of executives familiar with the investments, reviews periodic financial information, including audited financial statements when available. Certain valuation analytics may be employed that include current and projected financial performance, recent financing activities, economic and market conditions, market comparable companies, market liquidity, sales restrictions, and other factors. A significant change in the expected performance of the individual investment would result in a change in the fair value measurement of the investment. The amount of unfunded commitments to invest is disclosed in Note 16. Certain restrictions apply for the redemption of these investments and certain investments are prohibited by the Volcker Rule. See discussions in Notes 5 and 16. Agriculture Loan Servicing This asset results from our servicing of agriculture loans approved and funded by Federal Agricultural Mortgage Corporation (“FAMC”). We provide this servicing under an agreement with FAMC for loans they own. The asset’s fair value represents our projection of the present value of future cash flows measured under Level 3 using discounted cash flow methodologies. Interest-only Strips Interest-only strips are created as a by-product of the securitization process. When the guaranteed portions of Small Business Administration (“SBA”) 7(a) loans are pooled, interest-only strips may be created in the pooling process. The asset’s fair value represents our projection of the present value of future cash flows measured under Level 3 using discounted cash flow methodologies. Deferred Compensation Plan Assets and Obligations Invested assets in the deferred compensation plan consist of shares of registered investment companies. These mutual funds are valued under Level 1 at quoted market prices, which represents the NAV of shares held by the plan at the end of the period. Derivatives Derivatives are measured according to their classification as either exchange-traded or over-the-counter. Exchange-traded derivatives consist of foreign currency exchange contracts measured under Level 1 because they are traded in active markets. Over-the-counter derivatives, including those for customers, consist of interest rate swaps and options. These derivatives are measured under Level 2 using third-party services. Observable market inputs include yield curves — the London Interbank Offered Rate (“LIBOR”) swap curve and relevant overnight index swap curves — foreign exchange rates, commodity prices, option volatilities, counterparty credit risk, and other related data. Credit valuation adjustments are required to reflect nonperformance risk for both us and the respective counterparty. These adjustments are determined generally by applying a credit spread to the total expected exposure of the derivative. Securities Sold, Not Yet Purchased Securities sold, not yet purchased, included in “Federal funds and other short-term borrowings” on the balance sheet, are measured under Level 1 using quoted market prices. If not available, quoted prices under Level 2 for similar securities are used. Loans Loans are generally measured at amortized cost, unless they do not share risk characteristics with other loans. For those loans, we estimate lifetime expected credit losses on an individual basis. When a loan is individually evaluated for expected credit losses, we estimate a specific reserve for the loan based on either the projected present value of the loan’s future cash flows discounted at the loan’s effective interest rate, the observable market price of the loan, or the fair value of the loan’s underlying collateral. See Note 6 for more information regarding the measurement method for our loans. For loans measured at amortized cost, fair value is estimated by discounting future cash flows using the applicable yield curve adjusted by a factor that reflects the credit, interest rate risk, and liquidity inherent in the loan. These future cash flows are then reduced by the estimated life-of-the-loan aggregate credit losses in the loan portfolio (i.e., the allowance for loan and lease losses under the CECL model). Quantitative Disclosure by Fair Value Hierarchy Assets and liabilities measured at fair value by class on a recurring basis are summarized as follows: (In millions) December 31, 2020 Level 1 Level 2 Level 3 Total ASSETS Investment securities: Available-for-sale: U.S. Treasury, agencies and corporations $ 192 $ 13,944 $ — $ 14,136 Municipal securities 1,420 1,420 Other debt securities 175 175 Total Available-for-sale 192 15,539 — 15,731 Trading account 111 155 266 Other noninterest-bearing investments: Bank-owned life insurance 532 532 Private equity investments 1 80 80 Other assets: Agriculture loan servicing and interest-only strips 16 16 Deferred compensation plan assets 120 120 Derivatives: Derivatives not designated as hedges: Interest rate 411 411 Foreign exchange 4 4 Total Assets $ 427 $ 16,637 $ 96 $ 17,160 LIABILITIES Securities sold, not yet purchased $ 61 $ — $ — $ 61 Other liabilities: Derivatives: Derivatives not designated as hedges: Interest rate 34 34 Foreign exchange 4 4 Total Liabilities $ 65 $ 34 $ — $ 99 1 The level 1 PEIs amount relates to the portion of our SBIC investments that are now publicly traded. (In millions) December 31, 2019 Level 1 Level 2 Level 3 Total ASSETS Investment securities: Available-for-sale: U.S. Treasury, agencies and corporations $ 25 $ 12,356 $ — $ 12,381 Municipal securities 1,319 1,319 Other debt securities 25 25 Total Available-for-sale 25 13,700 — 13,725 Trading account 65 117 182 Other noninterest-bearing investments: Bank-owned life insurance 525 525 Private equity investments 9 107 116 Other assets: Agriculture loan servicing and interest-only strips 18 18 Deferred compensation plan assets 113 113 Derivatives: Derivatives not designated as hedges: Interest rate 149 149 Foreign exchange 4 4 Total Assets $ 216 $ 14,491 $ 125 $ 14,832 LIABILITIES Securities sold, not yet purchased $ 66 $ — $ — $ 66 Other liabilities: Derivatives: Derivatives not designated as hedges: Interest rate 15 15 Foreign exchange 4 4 Total Liabilities $ 70 $ 15 $ — $ 85 Reconciliation of Level 3 Fair Value Measurements The following schedule reconciles the beginning and ending balances of assets and liabilities that are measured at fair value by financial instrument on a recurring basis using Level 3 inputs: Level 3 Instruments December 31, 2020 December 31, 2019 (In millions) Private Ag loan svcg and int-only strips Private Ag loan svcg and int-only strips Balance at beginning of year $ 107 $ 18 $ 102 $ 18 Securities gains (losses), net (5) — 2 — Other noninterest income (expense) — (1) — 1 Purchases 9 — 10 — Redemptions and paydowns — (1) — (1) Other (31) — (7) — Balance at end of year $ 80 $ 16 $ 107 $ 18 1 This represents the value of a private equity investment at the beginning of the quarter during which it became publicly traded. During the third quarter of 2019, one of our PEIs became publicly traded and was transferred from Level 3 to Level 1. There were no transfers of assets or liabilities into, or out of, Level 3 for 2020. The reconciliation of Level 3 instruments includes the following realized gains and losses in the statement of income: (In millions) Year Ended 2020 2019 Securities gains (losses), net $ 18 $ (9) Nonrecurring Fair Value Measurements Included in the balance sheet amounts are the following amounts of assets that had fair value changes measured on a nonrecurring basis: (In millions) Fair value at December 31, 2020 Gains (losses) from Level 1 Level 2 Level 3 Total ASSETS Private equity investments, carried at cost $ — $ — $ 1 $ 1 $ (1) Collateral-dependent loans — 14 — 14 (14) Other real estate owned — 1 — 1 (2) Total $ — $ 15 $ 1 $ 16 $ (17) (In millions) Fair value at December 31, 2019 Gains (losses) from Level 1 Level 2 Level 3 Total ASSETS Private equity investments, carried at cost $ — $ — $ 1 $ 1 $ (1) Collateral-dependent loans — — — — — Other real estate owned — — — — (1) Total $ — $ — $ 1 $ 1 $ (2) The previous fair values may not be current as of the dates indicated, but rather as of the most recent date the fair value change occurred. Accordingly, carrying values may not equal the current fair value. We recognized net gains of $1 million in 2020 and $3 million in 2019 from the sale of OREO properties that had a carrying value at the time of sale of approximately $6 million in 2020 and $5 million in 2019. Prior to their sale in these years, we recognized an insignificant amount of impairment on these properties in 2020 and 2019. PEIs carried at cost were measured at fair value for impairment purposes according to the methodology previously described for these investments. Amounts of PEIs carried at cost were $8 million at December 31, 2020 and at December 31, 2019. Amounts of other noninterest-bearing investments carried at cost were $109 million and $157 million at December 31, 2020, and 2019, respectively, which were comprised of Federal Reserve and Federal Home Loan Bank (“FHLB”) stock. PEIs accounted for using the equity method were $61 million and $45 million at December 31, 2020, and 2019, respectively. Loans that are collateral-dependent were measured at the lower of amortized cost or the fair value of the collateral. OREO was measured initially at fair value based on collateral appraisals at the time of transfer and subsequently at the lower of cost or fair value. Measurement of fair value for collateral-dependent loans and OREO was based on third-party appraisals that utilize one or more valuation techniques (income, market and/or cost approaches). Any adjustments to calculated fair value were made based on recently completed and validated third-party appraisals, third-party appraisal services, automated valuation services, or our informed judgment. Evaluations were made to determine that the appraisal process met the relevant concepts and requirements of applicable accounting guidance. Automated valuation services may be used primarily for residential properties when values from any of the previous methods were not available within 90 days of the balance sheet date. These services use models based on market, economic, and demographic values. The use of these models has only occurred in very few instances and the related property valuations have not been sufficiently significant to consider disclosure under Level 3 rather than Level 2. Loans that are not collateral-dependent were measured as previously discussed in this Note. Fair Value of Certain Financial Instruments Following is a summary of the carrying values and estimated fair values of certain financial instruments: December 31, 2020 December 31, 2019 (In millions) Carrying Estimated Level Carrying Estimated Level Financial assets: Held-to-maturity investment securities $ 636 $ 640 2 $ 592 $ 597 2 Loans and leases (including loans held for sale), net of allowance 52,780 53,221 3 48,343 47,958 3 Financial liabilities: Time deposits 2,588 2,603 2 4,719 4,725 2 Long-term debt 1,336 1,346 2 1,723 1,751 2 This summary excludes financial assets and liabilities for which carrying value approximates fair value and financial instruments that are recorded at fair value on a recurring basis. Financial instruments for which carrying values approximate fair value include cash and due from banks, money market investments, demand, savings and money market deposits, federal funds purchased and other short-term borrowings, and security repurchase agreements. The estimated fair value of demand, savings and money market deposits is the amount payable on demand at the reporting date. Carrying value is used because the accounts have no stated maturity and the customer has the ability to withdraw funds immediately. Time and foreign deposits, and any other short-term borrowings, are measured at fair value by discounting future cash flows using the LIBOR yield curve to the given maturity dates. Long-term debt is measured at fair value based on actual market trades (i.e., an asset value) when available, or discounting cash flows to maturity using the LIBOR yield curve adjusted for credit spreads. The methods used to measure fair value for HTM securities and loans were previously described in this Note. These fair value disclosures represent our best estimates based on relevant market information and information about the financial instruments. Fair value estimates are based on judgments regarding current economic conditions, future expected loss experience, risk characteristics of the various instruments, and other factors. These estimates are subjective in nature, involve uncertainties and matters of significant judgment, and cannot be determined with precision. Changes in these methodologies and assumptions could significantly affect the estimates.

Offsetting Assets and Liabiliti

Offsetting Assets and Liabilities	12 Months Ended
	Dec. 31, 2020
Offsetting [Abstract]
OFFSETTING ASSETS AND LIABILITIES	OFFSETTING ASSETS AND LIABILITIES Gross and net information for selected financial instruments in the balance sheet is as follows: December 31, 2020 (In millions) Gross amounts not offset in the balance sheet Description Gross amounts recognized Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Cash collateral received/pledged Net amount Assets: Federal funds sold and security resell agreements $ 6,457 $ (692) $ 5,765 $ — $ — $ 5,765 Derivatives (included in other assets) 418 — 418 (6) (3) 409 Total assets $ 6,875 $ (692) $ 6,183 $ (6) $ (3) $ 6,174 Liabilities: Federal funds and other short-term borrowings $ 2,264 $ (692) $ 1,572 $ — $ — $ 1,572 Derivatives (included in other liabilities) 38 — 38 (6) (26) 6 Total liabilities $ 2,302 $ (692) $ 1,610 $ (6) $ (26) $ 1,578 December 31, 2019 (In millions) Gross amounts not offset in the balance sheet Description Gross amounts recognized Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Cash collateral received/pledged Net amount Assets: Federal funds sold and security resell agreements $ 694 $ (210) $ 484 $ — $ — $ 484 Derivatives (included in other assets) 153 — 153 (6) — 147 Total assets $ 847 $ (210) $ 637 $ (6) $ — $ 631 Liabilities: Federal funds and other short-term borrowings $ 2,263 $ (210) $ 2,053 $ — $ — $ 2,053 Derivatives (included in other liabilities) 19 — 19 (6) (10) 3 Total liabilities $ 2,282 $ (210) $ 2,072 $ (6) $ (10) $ 2,056 Security repurchase and reverse repurchase (“resell”) agreements are offset, when applicable, in the balance sheet according to master netting agreements. Security repurchase agreements are included with “Federal funds and other short-term borrowings.” Derivative instruments may be offset under their master netting agreements; however, for accounting purposes, we present these items on a gross basis in our balance sheet. See Note 7 for further information regarding derivative instruments.

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Investments [Abstract]
INVESTMENTS	INVESTMENTS Investment Securities Investment securities are classified as HTM, AFS, or trading. HTM securities, which management has the intent and ability to hold until maturity, are carried at amortized cost. AFS securities are carried at fair value and unrealized gains and losses are reported as net increases or decreases to accumulated other comprehensive income (“AOCI”). Trading securities are carried at fair value with gains and losses recognized in current period earnings. The carrying values of our securities do not include accrued interest receivables of $54 million and $58 million at December 31, 2020, and 2019, respectively. These receivables are presented in the “Consolidated Balance Sheet” within the “Other Assets” line item. The purchase premiums for callable debt securities classified as HTM or AFS are amortized at an effective yield to the earliest call date. The purchase premiums and discounts for all other HTM and AFS securities are recognized in interest income over the contractual life of the security using the effective yield method. As principal prepayments are received on securities, a proportionate amount of the related premium or discount is recognized in income so that the effective yield on the remaining portion of the security continues unchanged. Note 3 discusses the process to estimate fair value for investment securities. December 31, 2020 (In millions) Amortized Gross Gross Estimated Held-to-maturity Municipal securities $ 636 $ 5 $ 1 $ 640 Available-for-sale U.S. Treasury securities 205 — 13 192 U.S. Government agencies and corporations: Agency securities 1,051 40 — 1,091 Agency guaranteed mortgage-backed securities 11,439 262 8 11,693 Small Business Administration loan-backed securities 1,195 — 35 1,160 Municipal securities 1,352 68 — 1,420 Other debt securities 175 — — 175 Total available-for-sale 15,417 370 56 15,731 Total investment securities $ 16,053 $ 375 $ 57 $ 16,371 December 31, 2019 (In millions) Amortized Gross Gross Estimated Held-to-maturity Municipal securities $ 592 $ 5 $ — $ 597 Available-for-sale U.S. Treasury securities 25 — — 25 U.S. Government agencies and corporations: Agency securities 1,301 5 4 1,302 Agency guaranteed mortgage-backed securities 9,518 83 42 9,559 Small Business Administration loan-backed securities 1,535 1 41 1,495 Municipal securities 1,282 37 — 1,319 Other debt securities 25 — — 25 Total available-for-sale 13,686 126 87 13,725 Total investment securities $ 14,278 $ 131 $ 87 $ 14,322 Maturities The following schedule shows the amortized cost and weighted average yields of investment debt securities by contractual maturity of principal payments as of December 31, 2020. Actual principal payments may differ from contractual or expected principal payments because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. December 31, 2020 Total debt investment securities Due in one year or less Due after one year through five years Due after five years through 10 years Due after 10 years (Dollar amounts in millions) Amortized cost Avg yield Amortized cost Avg yield Amortized cost Avg yield Amortized cost Avg yield Amortized cost Avg yield Held-to-maturity Municipal securities 1 $ 636 3.08 % $ 146 2.05 % $ 187 3.42 % $ 174 3.19 % $ 129 3.58 % Available-for-sale U.S. Treasury securities 205 0.99 50 0.09 — — — — 155 1.28 U.S. Government agencies and corporations: Agency securities 1,051 2.36 — — 292 1.73 238 2.65 521 2.58 Agency guaranteed mortgage-backed securities 11,439 1.87 — — 372 1.48 728 1.77 10,339 1.89 Small Business Administration loan-backed securities 1,195 1.56 — — 43 1.39 137 1.61 1,015 1.56 Municipal securities 1 1,352 2.44 99 1.83 640 2.39 432 2.60 181 2.59 Other debt securities 175 1.05 — — — — 160 0.87 15 2.93 Total available-for-sale securities 15,417 1.91 149 1.24 1,347 1.96 1,695 2.01 12,226 1.89 Total investment securities $ 16,053 1.95 % $ 295 1.64 % $ 1,534 2.14 % $ 1,869 2.12 % $ 12,355 1.91 % 1 The yields on tax-exempt securities are calculated on a tax-equivalent basis. The following schedule summarizes the amount of gross unrealized losses for debt securities and the estimated fair value by length of time the securities have been in an unrealized loss position: December 31, 2020 Less than 12 months 12 months or more Total (In millions) Gross Estimated Gross Estimated Gross Estimated Held-to-maturity Municipal securities $ 1 $ 96 $ — $ 12 $ 1 $ 108 Available-for-sale U.S. Treasury securities 13 142 — — 13 142 U.S. Government agencies and corporations: Agency securities — 6 — 2 — 8 Agency guaranteed mortgage-backed securities 7 1,197 1 179 8 1,376 Small Business Administration loan-backed securities — 15 35 1,068 35 1,083 Municipal securities — 19 — — — 19 Other — 150 — — — 150 Total available-for-sale 20 1,529 36 1,249 56 2,778 Total investment securities $ 21 $ 1,625 $ 36 $ 1,261 $ 57 $ 2,886 December 31, 2019 Less than 12 months 12 months or more Total (In millions) Gross Estimated Gross Estimated Gross Estimated Held-to-maturity Municipal securities $ — $ 73 $ — $ 45 $ — $ 118 Available-for-sale U.S. Government agencies and corporations: Agency securities 2 222 2 359 4 581 Agency guaranteed mortgage-backed securities 4 1,173 38 3,215 42 4,388 Small Business Administration loan-backed securities 1 172 40 1,215 41 1,387 Municipal securities — 50 — 5 — 55 Other — — — — — — Total available-for-sale 7 1,617 80 4,794 87 6,411 Total investment securities $ 7 $ 1,690 $ 80 $ 4,839 $ 87 $ 6,529 Approximately 119 and 146 HTM and 549 and 849 AFS investment securities were in an unrealized loss position at December 31, 2020, and 2019, respectively. Impairment Ongoing Policy We review investment securities on a quarterly basis for the presence of impairment. For AFS securities, we assess whether impairment is present on an individual security basis when the fair value of a debt security is less than its amortized cost basis at the balance sheet date. When determining if the fair value of an investment is less than the amortized cost basis, we have elected to exclude accrued interest from the amortized cost basis of the investment. If we have an intent to sell an identified security, or it is more likely than not we will be required to sell the security before recovery of its amortized cost basis, then we recognize an impairment equal to any existing allowance written off against the security. If we do not have the intent to sell a security, and it is more likely than not that we will not be required to sell a security prior to recovery of its amortized cost basis, then we determine whether there is any impairment attributable to credit-related factors. We analyze certain factors, primarily internal and external credit ratings, to determine if the decline in fair value below the amortized cost basis has resulted from a credit loss or other factors. If a credit impairment is determined to exist, then we measure the amount of credit loss and recognize an allowance for the credit loss. In measuring the credit loss, we generally compare the present value of cash flows expected to be collected from the security to the amortized cost basis of the security. These cash flows are credit adjusted using, among other things, assumptions for default probability and loss severity. Certain other unobservable inputs, such as prepayment rate assumptions, are also utilized. In addition, certain internal models may be utilized. To determine the credit-related portion of impairment, we use the security-specific effective interest rate when estimating the present value of cash flows. If the present value of cash flows is less than the amortized cost basis of the security, then this amount is recorded as an allowance for credit loss, limited to the amount that the fair value is less than the amortized cost basis (i.e., the credit impairment cannot result in the security being carried at an amount lower than its fair value). The assumptions used to estimate the expected cash flows depends on the particular asset class, structure and credit rating of the security. Declines in fair value that are not recorded in the allowance are recorded in other comprehensive income, net of applicable taxes. AFS Impairment Conclusions We did not recognize any impairment on our AFS investment securities portfolio during 2020 or 2019. Unrealized losses relate to changes in interest rates subsequent to purchase and are not attributable to credit. At December 31, 2020, we had not initiated any sales of AFS securities nor did we have an intent to sell any identified securities with unrealized losses, and we do not believe it is more likely than not we would be required to sell such securities before recovery of their amortized cost basis. HTM Impairment Conclusions For HTM securities, the ACL is assessed consistent with the approach described in Note 6 for loans carried at amortized cost. The ACL on HTM securities was less than $1 million at December 31, 2020. All HTM securities were risk-graded as “pass” in terms of credit quality and none were past due as of December 31, 2020. The amortized cost basis of HTM securities categorized by year of issuance is summarized as follows: December 31, 2020 Amortized cost basis by year of issuance (In millions) 2020 2019 2018 2017 2016 Prior Total Securities Held-to-maturity $ 216 $ 18 $ — $ 12 $ 176 $ 214 $ 636 Securities Gains and Losses Recognized in Income The following summarizes gains and losses that were recognized in the statement of income: 2020 2019 2018 (In millions) Gross Gross Gross Gross Gross Gross Other noninterest-bearing investments $ 27 $ 20 $ 20 $ 17 $ 17 $ 16 Net gains $ 7 $ 3 $ 1 Interest income by security type is as follows: (In millions) 2020 2019 2018 Taxable Nontaxable Total Taxable Nontaxable Total Taxable Nontaxable Total Investment securities: Held-to-maturity $ 10 $ 10 $ 20 $ 9 $ 13 $ 22 $ 10 $ 14 $ 24 Available-for-sale 252 25 277 308 25 333 295 26 321 Trading — 7 7 1 6 7 1 4 5 Total $ 262 $ 42 $ 304 $ 318 $ 44 $ 362 $ 306 $ 44 $ 350 Investment securities with a carrying value of approximately $2.3 billion and $2.0 billion at December 31, 2020, and 2019, respectively, were pledged to secure public and trust deposits, advances, and for other purposes as required by law. Securities are also pledged as collateral for security repurchase agreements.

Loans, Leases, and Allowance Fo

Loans, Leases, and Allowance For Credit Losses	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
LOANS, LEASES, AND ALLOWANCE FOR CREDIT LOSSES	LOANS, LEASES, AND ALLOWANCE FOR CREDIT LOSSES Loans, Leases, and Loans Held for Sale Loans and leases are summarized as follows according to major portfolio segment and specific class: December 31, (In millions) 2020 2019 Loans held for sale $ 81 $ 129 Commercial: Commercial and industrial $ 13,444 $ 14,760 PPP 5,572 — Leasing 320 334 Owner-occupied 8,185 7,901 Municipal 2,951 2,393 Total commercial 30,472 25,388 Commercial real estate: Construction and land development 2,345 2,211 Term 9,759 9,344 Total commercial real estate 12,104 11,555 Consumer: Home equity credit line 2,745 2,917 1-4 family residential 6,969 7,568 Construction and other consumer real estate 630 624 Bankcard and other revolving plans 432 502 Other 124 155 Total consumer 10,900 11,766 Total loans and leases $ 53,476 $ 48,709 Loans and leases are presented at their amortized cost basis, which includes net unamortized purchase premiums, discounts, and deferred loan fees and costs totaling $149 million and $60 million at December 31, 2020, and December 31, 2019, respectively. Amortized cost basis does not include accrued interest receivables of $200 million and $164 million at December 31, 2020, and December 31, 2019, respectively. These receivables are presented in the “Consolidated Balance Sheet” within the “Other Assets” line item. Municipal loans generally include loans to municipalities with the debt service being repaid from general funds or pledged revenues of the municipal entity, or to private commercial entities or 501(c)(3) not-for-profit entities utilizing a pass-through municipal entity to achieve favorable tax treatment. Land acquisition and development loans included in the construction and land development loan portfolio were $156 million at December 31, 2020 and $158 million at December 31, 2019. Loans with a carrying value of approximately $24.7 billion at December 31, 2020, and $21.5 billion at December 31, 2019, have been pledged at the Federal Reserve and the FHLB of Des Moines as collateral for current and potential borrowings. We sold loans totaling $1.8 billion in 2020, $872 million in 2019, and $585 million in 2018, that were classified as loans held for sale. The sold loans were derecognized from the balance sheet. Loans classified as loans held for sale primarily consisted of conforming residential mortgages and the guaranteed portion of SBA loans, and did not consist of loans from the SBA’s Paycheck Protection Program. The loans are mainly sold to U.S. government agencies or participated to third-parties. At times, we have continuing involvement in the transferred loans in the form of servicing rights or a guarantee from the respective issuer. Amounts added to loans held for sale during these same periods were $1.8 billion, $916 million, and $785 million, respectively. See Note 5 for further information regarding guaranteed securities. The principal balance of sold loans for which we retain servicing was approximately $2.8 billion at December 31, 2020, $1.7 billion at December 31, 2019, and $2.2 billion at December 31, 2018. Income from loans sold, excluding servicing, was $54 million in 2020, $18 million in 2019, and $12 million in 2018. Allowance for Credit Losses The ACL, which consists of the allowance for loan and lease losses (“ALLL”) and the reserve for unfunded lending commitments (“RULC”), represents our estimate of current expected credit losses over the contractual term of the loan and lease portfolio and unfunded lending commitments as of the balance sheet date. The ACL for AFS and HTM debt securities is estimated separately from loans. For HTM securities, the ACL is assessed consistent with the approach for loans carried at amortized cost. See Note 5 for further discussion on our assessment of expected credit losses on AFS securities and disclosures related to AFS and HTM securities. We determine our ACL as the best estimate within a range of estimated current expected losses by using the loan’s amortized cost basis (principal balance, net of unamortized premiums, discounts, and deferred fees and costs). We do not estimate the ACL for accrued interest receivables because we reverse or write-off uncollectible accrued interest receivable balances in a timely manner, generally within one month. The methodologies we use to estimate the ACL depend upon the type of loan, the age and contractual term of the loan, expected payments (both contractual and assumed prepayments), credit quality indicators, economic forecasts, and the evaluation method (whether individually or collectively evaluated). Expected loan extensions, renewals, or modifications are not considered in the ACL, unless they are included in the original or modified contract at the reporting date and are not unconditionally cancellable, or we reasonably expect them to result in a TDR. Losses are charged to the ACL when recognized. Generally, commercial and commercial real estate (“CRE”) loans are charged off or charged down when they are determined to be uncollectible in whole or in part, or when 180 days past due, unless the loan is well-secured and in process of collection. Consumer loans are either charged off or charged down to net realizable value no later than the month in which they become 180 days past due. Closed-end consumer loans that are not secured by residential real estate are either charged off or charged down to net realizable value no later than the month in which they become 120 days past due. We establish the amount of the ACL by analyzing the portfolio at least quarterly, and we adjust the provision for loan losses and unfunded lending commitments to ensure the ACL is at an appropriate level at the balance sheet date. For commercial and CRE loans with commitments greater than $1 million, we assign internal risk grades using a comprehensive loan grading system based on financial and statistical models, individual credit analysis, and loan officer experience and judgment. The credit quality indicators described subsequently are based on this grading system. Estimated credit losses on all loan segments, including consumer and small commercial and CRE loans with commitments less than or equal to $1 million that are evaluated on a collective basis, are derived from statistical analyses of our historical default and loss experience since January 2008. We estimate current expected credit losses over the contractual remaining life of each loan, which considers historical credit loss experience, current conditions, and reasonable and supportable forecasts about the future. We use the following two types of credit loss estimation models: • Econometric loss models, which rely on statistical analyses of our historical loss experience dependent upon economic factors and other loan-level characteristics. Statistically relevant economic factors vary depending upon the type of loan, but include variables such as unemployment, real estate price indices, energy prices, GDP, etc. The results associated with several economic scenarios are weighted to produce the credit loss estimate from these models. • Loss models that are based on our long-term average historical credit loss experience since 2008, which rely on statistical analyses of our historical loss experience dependent upon loan-level characteristics. Estimated credit losses during the first 12 months of a loan’s contractual remaining life, or reasonable and supportable period, are derived from the econometric loss models. Over a subsequent 12-month reversion period, we blend the estimated credit losses from the two models on a straight-line basis. For the remaining life of the loan, the estimated credit losses are derived from the long-term average historical credit loss models. For loans that do not share risk characteristics with other loans, we estimate lifetime expected credit losses on an individual basis. We consider individually evaluated loans to be nonaccrual loans with a balance greater than $1 million; TDR loans, including TDRs that subsequently default; a loan no longer reported as a TDR; or a loan where we reasonably expect it to become a TDR. When a loan is individually evaluated for expected credit losses, we estimate a specific reserve for the loan based on either the projected present value of the loan’s future cash flows discounted at the loan’s effective interest rate, the observable market price of the loan, or the fair value of the loan’s underlying collateral. The process of estimating future cash flows also incorporates the same determining factors described subsequently under nonaccrual loans. When we base the specific reserve on the fair value of the loan’s underlying collateral, we generally charge off the portion of the balance that is greater than fair value. For these loans, subsequent to the charge-off, if the fair value of the loan’s underlying collateral increases according to an updated appraisal, we hold a negative reserve up to the lesser of the amount of the charge-off or the updated fair value. The methodologies described above generally rely on historical loss information to help determine our quantitative portion of the ACL. However, we also consider other qualitative and environmental factors related to current conditions and reasonable and supportable forecasts that may indicate current expected credit losses may differ from the historical information reflected in our quantitative models. Thus, after applying historical loss experience, as described above, we review the quantitative portion of ACL for each segment using qualitative criteria, and we use those criteria to determine our qualitative estimate. We monitor various risk factors that influence our judgment regarding the level of the ACL across the portfolio segments. These factors primarily include: • Actual and expected changes in international, national, regional, and local economic and business conditions and developments; • The volume and severity of past due loans, the volume of nonaccrual loans, and the volume and severity of adversely classified or graded loans; • Lending policies and procedures, including changes in underwriting standards and practices for collection, charge-off, and recovery; • The experience, ability, and depth of lending management and other relevant staff; • The nature and volume of the portfolio; • The quality of the credit review function; • The existence, growth, and effect of any concentration of credit; • The effect of other external factors such as regulatory, legal, and technological environments; fiscal and monetary actions; competition; and events such as natural disasters and pandemics. The magnitude of the impact of these factors on our qualitative assessment of the ACL changes from quarter to quarter according to changes made by management in its assessment of these factors, the extent these factors are already reflected in quantitative loss estimates, and the extent changes in these factors diverge from one to another. We also consider the uncertainty and imprecision inherent in the estimation process when evaluating the ACL. Off-balance-sheet Credit Exposures As previously mentioned, we estimate current expected credit losses for off-balance-sheet loan commitments, including standby letters of credit, that are not unconditionally cancelable. This estimate uses the same procedures and methodologies described previously for loans and is calculated by taking the difference between the estimated current expected credit loss and the funded balance, if greater than zero. Changes in the Allowance for Credit Losses On January 1, 2020, we adopted ASU 2016-13, or CECL. Due to the adoption of the standard, the ACL methodology explained above has significantly changed from the prior period. Changes in the ACL are summarized as follows: December 31, 2020 (In millions) Commercial Commercial Consumer Total Allowance for loan losses Balance at December 31, 2019 $ 341 $ 101 $ 53 $ 495 Adjustment for change in accounting standard (59) (32) 93 2 Balance at beginning of year (January 1, 2020) 282 69 146 497 Provision for loan losses 281 103 1 385 Gross loan and lease charge-offs 113 1 14 128 Recoveries 14 — 9 23 Net loan and lease charge-offs (recoveries) 99 1 5 105 Balance at end of year $ 464 $ 171 $ 142 $ 777 Reserve for unfunded lending commitments Balance at December 31, 2019 $ 39 $ 20 $ — $ 59 Adjustment for change in accounting standard (28) (8) 6 (30) Balance at beginning of year (January 1, 2020) 11 12 6 29 Provision for unfunded lending commitments 19 8 2 29 Balance at end of year $ 30 $ 20 $ 8 $ 58 Total allowance for credit losses Allowance for loan losses $ 464 $ 171 $ 142 $ 777 Reserve for unfunded lending commitments 30 20 8 58 Total allowance for credit losses $ 494 $ 191 $ 150 $ 835 December 31, 2019 (In millions) Commercial Commercial Consumer Total Allowance for loan losses Balance at beginning of year $ 331 $ 110 $ 54 $ 495 Provision for loan losses 42 (11) 6 37 Gross loan and lease charge-offs 57 4 17 78 Recoveries 25 6 10 41 Net loan and lease charge-offs (recoveries) 32 (2) 7 37 Balance at end of year $ 341 $ 101 $ 53 $ 495 Reserve for unfunded lending commitments Balance at beginning of year $ 40 $ 17 $ — $ 57 Provision for unfunded lending commitments (1) 3 — 2 Balance at end of year $ 39 $ 20 $ — $ 59 Total allowance for credit losses Allowance for loan losses $ 341 $ 101 $ 53 $ 495 Reserve for unfunded lending commitments 39 20 — 59 Total allowance for credit losses $ 380 $ 121 $ 53 $ 554 Nonaccrual Loans Loans are generally placed on nonaccrual status when payment in full of principal and interest is not expected, or the loan is 90 days or more past due as to principal or interest, unless the loan is both well-secured and in the process of collection. Factors we consider in determining whether a loan is placed on nonaccrual include delinquency status, collateral-value, borrower or guarantor financial statement information, bankruptcy status, and other information which would indicate that the full and timely collection of interest and principal is uncertain. A nonaccrual loan may be returned to accrual status when all delinquent interest and principal become current in accordance with the terms of the loan agreement; the loan, if secured, is well-secured; the borrower has paid according to the contractual terms for a minimum of six months; and an analysis of the borrower indicates a reasonable assurance of the ability and willingness to maintain payments. The amortized cost basis of loans on nonaccrual status is summarized as follows: December 31, 2020 Amortized cost basis Total amortized cost basis (In millions) with no allowance with allowance Related allowance Commercial: Commercial and industrial $ 73 $ 67 $ 140 $ 22 Leasing — — — — Owner-occupied 38 38 76 — Municipal — — — 4 Total commercial 111 105 216 26 Commercial real estate: Construction and land development — — — — Term 12 19 31 3 Total commercial real estate 12 19 31 3 Consumer: Home equity credit line 2 14 16 3 1-4 family residential 14 89 103 9 Construction and other consumer real estate — — — — Bankcard and other revolving plans — 1 1 1 Other — — — — Total consumer loans 16 104 120 13 Total $ 139 $ 228 $ 367 $ 42 The amount of accrued interest receivables written off by reversing interest income during the period is summarized by loan portfolio segment as follows: (In millions) Year Ended December 31, 2020 Commercial $ 16 Commercial real estate 2 Consumer 1 Total $ 19 Past Due Loans Closed-end loans with payments scheduled monthly are reported as past due when the borrower is in arrears for two or more monthly payments. Similarly, open-end credits, such as charge-card plans and other revolving credit plans, are reported as past due when the minimum payment has not been made for two or more billing cycles. Other multi-payment obligations (i.e., quarterly, semi-annual, etc.), single payment, and demand notes, are reported as past due when either principal or interest is due and unpaid for a period of 30 days or more. Past-due loans (accruing and nonaccruing) are summarized as follows: December 31, 2020 (In millions) Current 30-89 days 90+ days Total Total Accruing Nonaccrual loans that are current 1 Commercial: Commercial and industrial $ 13,388 $ 26 $ 30 $ 56 $ 13,444 $ 2 $ 109 PPP 5,572 — — — 5,572 — — Leasing 320 — — — 320 — 1 Owner-occupied 8,129 34 22 56 8,185 — 48 Municipal 2,951 — — — 2,951 — — Total commercial 30,360 60 52 112 30,472 2 158 Commercial real estate: Construction and land development 2,341 — 4 4 2,345 4 — Term 9,692 57 10 67 9,759 4 13 Total commercial real estate 12,033 57 14 71 12,104 8 13 Consumer: Home equity credit line 2,733 8 4 12 2,745 — 9 1-4 family residential 6,891 12 66 78 6,969 — 33 Construction and other consumer real estate 630 — — — 630 — Bankcard and other revolving plans 428 2 2 4 432 2 1 Other 123 1 — 1 124 — — Total consumer loans 10,805 23 72 95 10,900 2 43 Total $ 53,198 $ 140 $ 138 $ 278 $ 53,476 $ 12 $ 214 December 31, 2019 (In millions) Current 30-89 days 90+ days Total Total Accruing Nonaccrual loans that are current 1 Commercial: Commercial and industrial $ 14,665 $ 57 $ 38 $ 95 $ 14,760 $ 8 $ 54 Leasing 334 — — — 334 1 — Owner-occupied 7,862 20 19 39 7,901 — 44 Municipal 2,393 — — — 2,393 — — Total commercial 25,254 77 57 134 25,388 9 98 Commercial real estate: Construction and land development 2,206 5 — 5 2,211 — 1 Term 9,333 8 3 11 9,344 — 10 Total commercial real estate 11,539 13 3 16 11,555 — 11 Consumer: Home equity credit line 2,908 6 3 9 2,917 — 7 1-4 family residential 7,532 12 24 36 7,568 — 13 Construction and other consumer real estate 624 — — — 624 — — Bankcard and other revolving plans 499 2 1 3 502 1 — Other 154 1 — 1 155 — — Total consumer loans 11,717 21 28 49 11,766 1 20 Total $ 48,510 $ 111 $ 88 $ 199 $ 48,709 $ 10 $ 129 1 Represents nonaccrual loans that are not past due more than 30 days; however, full payment of principal and interest is still not expected. Credit Quality Indicators In addition to the nonaccrual and past due criteria, we also analyze loans using loan risk-grading systems, which vary based on the size and type of credit risk exposure. The internal risk grades assigned to loans follow our definitions of Pass, Special Mention, Substandard, and Doubtful, which are consistent with published definitions of regulatory risk classifications. Definitions of Pass, Special Mention, Substandard, and Doubtful are summarized as follows: • Pass — A Pass asset is higher-quality and does not fit any of the other categories described below. The likelihood of loss is considered low. • Special Mention — A Special Mention asset has potential weaknesses that deserve management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the asset or in our credit position at some future date. • Substandard — A Substandard asset is inadequately protected by the current sound worth and paying capacity of the obligor or of the collateral pledged, if any. Assets so classified have well-defined weaknesses and are characterized by the distinct possibility that we may sustain some loss if deficiencies are not corrected. • Doubtful — A Doubtful asset has all the weaknesses inherent in a Substandard asset with the added characteristics that the weaknesses make collection or liquidation in full highly questionable and improbable. The balance of loans classified as Doubtful as of December 31, 2020 was $4 million. There were no loans classified as Doubtful as of December 31, 2019. We generally assign internal risk grades to commercial and CRE loans with commitments greater than $1 million based on financial and statistical models, individual credit analysis, and loan officer experience and judgment. For these larger loans, we assign one of multiple grades within the Pass classification or one of the following four grades: Special Mention, Substandard, Doubtful, and Loss. Loss indicates that the outstanding balance has been charged off. We confirm our internal risk grades quarterly, or as soon as we identify information that affects the credit risk of the loan. For consumer loans and certain small commercial and CRE loans with commitments less than or equal to $1 million, we generally assign internal risk grades similar to those described previously based on automated rules that depend on refreshed credit scores, payment performance, and other risk indicators. These are generally assigned either a Pass, Special Mention, or Substandard grade, and are reviewed as we identify information that might warrant a grade change. The amortized cost basis of loans and leases categorized by year of origination and by credit quality classifications as monitored by management are summarized as follows: December 31, 2020 Term Loans Revolving loans amortized cost basis Revolving loans converted to term loans amortized cost basis Amortized cost basis by year of origination (In millions) 2020 2019 2018 2017 2016 Prior Total Commercial: Commercial and industrial Pass $ 2,585 $ 2,743 $ 1,903 $ 829 $ 296 $ 228 $ 3,298 $ 109 $ 11,991 Special Mention 79 152 183 98 4 43 110 1 670 Accruing Substandard 123 157 129 44 26 17 141 6 643 Nonaccrual 57 2 10 8 2 15 36 10 140 Total commercial and industrial 2,844 3,054 2,225 979 328 303 3,585 126 13,444 PPP Pass 5,572 — — — — — — — 5,572 Total PPP 5,572 — — — — — — — 5,572 Leasing Pass 87 121 44 34 14 5 — — 305 Special Mention 1 — 2 1 — 6 — — 10 Accruing Substandard 2 1 1 1 — — — — 5 Nonaccrual — — — — — — — — — Total leasing 90 122 47 36 14 11 — — 320 Owner-occupied Pass 1,588 1,205 1,167 895 585 1,806 161 11 7,418 Special Mention 72 65 60 60 51 41 9 3 361 Accruing Substandard 28 64 61 37 35 98 6 1 330 Nonaccrual 8 11 15 11 6 23 2 — 76 Total owner-occupied 1,696 1,345 1,303 1,003 677 1,968 178 15 8,185 Municipal Pass 1,031 827 359 419 68 227 3 — 2,934 Special Mention — — — — — 8 — — 8 Accruing Substandard — — — — — 9 — — 9 Nonaccrual — — — — — — — — — Total municipal 1,031 827 359 419 68 244 3 — 2,951 Total commercial 11,233 5,348 3,934 2,437 1,087 2,526 3,766 141 30,472 Commercial real estate: Construction and land development Pass 558 933 267 41 1 6 423 3 2,232 Special Mention 24 43 11 — — — 5 — 83 Accruing Substandard — 30 — — — — — — 30 Nonaccrual — — — — — — — — — Total construction and land development 582 1,006 278 41 1 6 428 3 2,345 Term Pass 2,524 1,858 1,639 761 778 1,291 73 20 8,944 Special Mention 110 89 177 42 23 85 — 5 531 Accruing Substandard 41 34 96 30 18 34 — — 253 Nonaccrual 3 5 — 2 1 20 — — 31 Total term 2,678 1,986 1,912 835 820 1,430 73 25 9,759 Total commercial real estate 3,260 2,992 2,190 876 821 1,436 501 28 12,104 December 31, 2020 Term Loans Revolving loans amortized cost basis Revolving loans converted to term loans amortized cost basis Amortized cost basis by year of origination (In millions) 2020 2019 2018 2017 2016 Prior Total Consumer: Home equity credit line Pass — — — — — — 2,606 115 2,721 Special Mention — — — — — — 2 — 2 Accruing Substandard — — — — — — 6 — 6 Nonaccrual — — — — — — 11 5 16 Total home equity credit line — — — — — — 2,625 120 2,745 1-4 family residential Pass 1,185 1,017 833 1,081 1,174 1,570 — — 6,860 Special Mention — — — — — 2 — — 2 Accruing Substandard — — 1 — 2 1 — — 4 Nonaccrual 2 12 7 19 15 48 — — 103 Total 1-4 family residential 1,187 1,029 841 1,100 1,191 1,621 — — 6,969 Construction and other consumer real estate Pass 200 296 106 16 1 11 — — 630 Special Mention — — — — — — — — — Accruing Substandard — — — — — — — — — Nonaccrual — — — — — — — — — Total construction and other consumer real estate 200 296 106 16 1 11 — — 630 Bankcard and other revolving plans Pass — — — — — — 426 2 428 Special Mention — — — — — — — — — Accruing Substandard — — — — — — 3 — 3 Nonaccrual — — — — — — — 1 1 Total bankcard and other revolving plans — — — — — — 429 3 432 Other consumer Pass 51 35 22 10 4 2 — — 124 Special Mention — — — — — — — — — Accruing Substandard — — — — — — — — — Nonaccrual — — — — — — — — — Total other consumer 51 35 22 10 4 2 — — 124 Total consumer 1,438 1,360 969 1,126 1,196 1,634 3,054 123 10,900 Total loans $ 15,931 $ 9,700 $ 7,093 $ 4,439 $ 3,104 $ 5,596 $ 7,321 $ 292 $ 53,476 Modified and Restructured Loans Loans may be modified in the normal course of business for competitive reasons or to strengthen our position. Loan modifications and restructurings may also occur when the borrower experiences financial difficulty and needs temporary or permanent relief from the original contractual terms of the loan. Loans that have been modified to accommodate a borrower who is experiencing financial difficulties, and for which we have granted a concession that we would not otherwise consider, are considered TDRs. We consider many factors in determining whether to agree to a loan modification involving concessions, and we seek a solution that will both minimize potential loss to us and attempt to help the borrower. We evaluate borrowers’ current and forecasted future cash flows, their ability and willingness to make current contractual or proposed modified payments, the value of the underlying collateral (if applicable), the possibility of obtaining additional security or guarantees, and the potential costs related to a repossession or foreclosure and the subsequent sale of the collateral. TDRs are classified as either accrual or nonaccrual loans. A loan on nonaccrual and restructured as a TDR will remain on nonaccrual status until the borrower has proven the ability to perform under the modified structure for a minimum of six months, and there is evidence that such payments can and are likely to continue as agreed. Performance prior to the restructuring, or significant events that coincide with the restructuring, are included in assessing whether the borrower can meet the new terms and may result in the loan being returned to accrual at the time of restructuring or after a shorter performance period. If the borrower’s ability to meet the revised payment schedule is uncertain, the loan remains classified as a nonaccrual loan. A TDR loan that specifies an interest rate that, at the time of the restructuring, is greater than or equal to the rate we are willing to accept for a new loan with comparable risk may not be reported as a TDR in the calendar years subsequent to the restructuring if it is in compliance with its modified terms. Consistent with recent accounting and regulatory guidance, loan modifications provided to borrowers experiencing financial difficulties exclusively related to the COVID-19 pandemic, in which we provide certain short-term modifications or payment deferrals, are not classified as TDRs. The TDRs disclosed subsequently do not include these loan modifications. Other loan modifications above and beyond these short-term modifications or payment deferrals were assessed for TDR classification. Selected information on TDRs at year-end that includes the recorded investment on an accruing and nonaccruing basis by loan class and modification type is summarized in the following schedules: December 31, 2020 Recorded investment resulting from the following modification types: (In millions) Interest Maturity Principal Payment Other 1 Multiple modification types 2 Total Accruing Commercial: Commercial and industrial $ — $ — $ — $ — $ 3 $ 4 $ 7 Owner-occupied 5 1 — 4 4 8 22 Total commercial 5 1 — 4 7 12 29 Commercial real estate: Construction and land development — — — — — — — Term 1 — — 16 94 23 134 Total commercial real estate 1 — — 16 94 23 134 Consumer: Home equity credit line — 1 7 — — 2 10 1-4 family residential 4 1 3 — 2 15 25 Construction and other consumer real estate — — — — — — — Total consumer loans 4 2 10 — 2 17 35 Total accruing $ 10 $ 3 $ 10 $ 20 $ 103 $ 52 $ 198 Nonaccruing Commercial: Commercial and industrial $ — $ — $ — $ 3 $ 10 $ 52 $ 65 Owner-occupied 5 — — 3 — 10 18 Municipal — — — — — — — Total commercial 5 — — 6 10 62 83 Commercial real estate: Construction and land development — — — — — — — Term 2 — — 13 3 2 20 Total commercial real estate 2 — — 13 3 2 20 Consumer: Home equity credit line — — 2 — — — 2 1-4 family residential 1 1 — — — 6 8 Construction and other consumer real estate — — — — — — — Total consumer loans 1 1 2 — — 6 10 Total nonaccruing 8 1 2 19 13 70 113 Total $ 18 $ 4 $ 12 $ 39 $ 116 $ 122 $ 311 1 Includes TDRs that resulted from other modification types including, but not limited to, a legal judgment awarded on different terms, a bankruptcy plan confirmed on different terms, a settlement that includes the delivery of collateral in exchange for debt reduction, etc. 2 Includes TDRs that resulted from a combination of any of the previous modification types. December 31, 2019 Recorded investment resulting from the following modification types: (In millions) Interest Maturity Principal Payment Other 1 Multiple modification types 2 Total Accruing Commercial: Commercial and industrial $ 1 $ 2 $ — $ — $ 8 $ 5 $ 16 Owner-occupied 3 1 — — 4 7 15 Total commercial 4 3 — — 12 12 31 Commercial real estate: Construction and land development — — — — — — — Term 2 — — 1 — 3 6 Total commercial real estate 2 — — 1 — 3 6 Consumer: Home equity credit line — 2 7 — — 2 11 1-4 family residential 1 1 4 — 1 22 29 Construction and other consumer real estate — 1 — — — — 1 Total consumer loans 1 4 11 — 1 24 41 Total accruing $ 7 $ 7 $ 11 $ 1 $ 13 $ 39 $ 78 Nonaccruing Commercial: Commercial and industrial $ — $ 4 $ — $ 20 $ 4 $ 22 $ 50 Owner-occupied 5 — — — 1 4 10 Municipal — — — — — — — Total commercial 5 4 — 20 5 26 60 Commercial real estate: Construction and land development — — — — — — — Term 1 — — — 3 3 7 Total commercial real estate 1 — — — 3 3 7 Consumer: Home equity credit line — — 2 — — — 2 1-4 family residential — — 1 — 1 4 6 Construction and other consumer real estate — — — — — — — Total consumer loans — — 3 — 1 4 8 Total nonaccruing 6 4 3 20 9 33 75 Total $ 13 $ 11 $ 14 $ 21 $ 22 $ 72 $ 153 1 Includes TDRs that resulted from other modification types including, but not limited to, a legal judgment awarded on different terms, a bankruptcy plan confirmed on different terms, a settlement that includes the delivery of collateral in exchange for debt reduction, etc. 2 Includes TDRs that resulted from a combination of any of the previous modification types. Unfunded lending commitments on TDRs amounted to approximately $3 million at December 31, 2020, and $5 million at December 31, 2019. The total recorded investment of all TDRs in which interest rates were modified below market was $76 million at December 31, 2020, and $73 million at December 31, 2019. These loans are included in the previous schedule in the columns for interest rate below market and multiple modification types. The net financial impact on interest income due to interest rate modifications below market for accruing TDRs for the years ended December 31, 2020 and 2019 was not significant. On an ongoing basis, we monitor the performance of all TDRs according to their restructured terms. Subsequent payment default is defined in terms of delinquency, when principal or interest payments are past due 90 days or more for commercial loans, or 60 days or more for consumer loans. The recorded investment of accruing and nonaccruing TDRs that had a payment default during the period listed below (and are still in default at year-end) and are within 12 months or less of being modified as TDRs is as follows: (In millions) December 31, 2020 December 31, 2019 Accruing Nonaccruing Total Accruing Nonaccruing Total Commercial: Commercial and industrial $ — $ 2 $ 2 $ — $ — $ — Owner-occupied — — — — 1 1 Total commercial — 2 2 — 1 1 Consumer: 1-4 family residential — 1 1 — — — Total consumer loans — 1 1 — — — Total $ — $ 3 $ 3 $ — $ 1 $ 1 Note: Total loans modified as TDRs during the 12 months previous to December 31, 2020, and 2019 were $228 million and $40 million, respectively. Collateral-dependent Loans As previously mentioned, when a loan is individually evaluated for expected credit losses, we estimate a specific reserve for the loan based on either the projected present value of the loan’s future cash flows discounted at the loan’s effective interest rate, the observable market price of the loan, or the fair value of the loan’s underlying collateral. Selected information on loans for which the repayment is expected to be provided substantially through the operation or sale of the underlying collateral and the borrower is experiencing financial difficulties, including the type of collateral and the extent to which the collateral secures the loans, is summarized as follows: December 31, 2020 (In millions) Amortized Cost Major Types of Col

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 31, 2020
Summary of Derivative Instruments [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES Objectives for using derivatives We maintain an overall interest rate risk management strategy that actively incorporates the use of interest rate derivatives that include unleveraged interest rate swaps, purchased options, combinations of options, and may include futures and other forward interest rate contracts. Our primary objective for using derivatives is to manage risks, primarily interest rate risk. We use derivatives to manage volatility in interest income, interest expense, earnings, and capital by adjusting our interest rate sensitivity to minimize the impact of fluctuations in interest rates. Derivatives are used to stabilize forecasted interest receipts from variable-rate assets and to modify the coupon or the duration of fixed-rate financial assets or liabilities as we consider advisable. We also use derivatives as a product for our customers to manage their risks. Derivatives related to interest rate risk management — When we use derivatives as hedges, either for economic or accounting purposes, it is done only to manage identified risks. We apply hedge accounting to certain derivatives executed for risk management purposes as subsequently described in more detail. However, we do not apply hedge accounting to all the derivatives involved in our risk management activities. Derivatives not designated as accounting hedges are not speculative and are used to economically manage our exposure to interest rate movements, including offsetting customer-facing derivatives. These derivatives either do not require the use of hedge accounting for their economic impact to be accurately reflected in our financial statements or they do not meet the strict hedge accounting requirements. Derivatives related to customers — We provide certain borrowers access to over-the-counter interest rate derivatives, which we generally offset with interest rate derivatives executed with other dealers or central clearing houses. Other interest rate derivatives that we provide to customers, or use for our own purposes, include mortgage rate locks and forward sale loan commitments. We also provide commercial clients with short-term foreign currency spot trades or forward contracts with a maturity of, generally, 90 days or less. These trades are also largely offset by foreign currency trades with closely mirroring terms executed with other dealer counterparties or central clearing houses. Accounting for derivatives We record all derivatives on the Consolidated Balance Sheet at fair value in Other Assets or Other Liabilities regardless of the accounting designation of each derivative. We enter into International Swaps and Derivatives Association, Inc. (“ISDA”) master netting agreements, or similar agreements, with substantially all derivative counterparties. See Note 4, “Offsetting Assets and Liabilities” for more information. Where legally enforceable, these master netting agreements give us, in the event of default or the triggering of other specified contingent events by the counterparty, the right to use cash or liquidate securities held as collateral and to offset receivables and payables with the same counterparty. For purposes of the Consolidated Balance Sheet, we do not offset derivative assets and liabilities and cash collateral held with the same counterparty where it has a legally enforceable master netting agreement and reports all derivatives on a gross fair value basis. Note 3 discusses the process to estimate fair value for derivatives. The accounting for changes in the fair value of derivatives depends on the intended use of the derivative and the resulting accounting designation. Derivatives used to hedge the exposure to changes in the fair value of assets, liabilities, or firm commitments attributable to interest rates or other eligible risks, are considered fair value hedges. Derivatives used to hedge the exposure to variability in expected future cash flows, or other types of forecasted transactions, are considered cash flow hedges. Changes in the fair value of derivatives that are not part of designated fair value or cash flow hedging relationships are recorded in current period earnings. Fair Value Hedges — We generally use interest rate swaps designated as fair value hedges to hedge changes in the fair value of fixed-rate assets and liabilities for specific risks (e.g., interest rate risk resulting from changes in a benchmark interest rate). We use both received-fixed, pay-floating and pay-fixed, receive floating interest rate swaps to effectively convert the fixed-rate assets and liabilities to floating-rates. In qualifying fair value hedges, changes in value of the derivative hedging instrument are recognized in current period earnings in the same line item affected by the hedged item. Similarly, the periodic changes in value of the hedged item, for the risk being hedged, are recognized in current period earnings, thereby offsetting all, or a significant majority, of the change in the value of the derivative hedging instrument. Interest accruals on both the derivative hedging instrument and the hedged item are recorded in the same line item, effectively converting the designated fixed-rate assets or liabilities to a floating-rate. Generally, the designated risk being hedged in all of our fair value hedges is the change in fair value of the London Interbank Offered Rate (“LIBOR”) benchmark swap rate component of the contractual coupon cash flows of the fixed-rate assets or liabilities. The swaps are structured to match the critical terms of the hedged items, maximizing the economic (and accounting) effectiveness of the hedging relationships and resulting in the expectation that the swaps will be highly effective as a hedging instrument. All interest rate swaps designated as fair value hedges were highly effective and met all other requirements to remain designated and part of qualifying hedge accounting relationships as of the balance sheet date. Fair Value Hedges of Liabilities — As of December 31, 2020, we had one receive-fixed interest rate swap with an aggregate notional amount of $500 million designated in a qualifying fair value hedge relationship of fixed-rate debt. The receive-fixed interest rate swap effectively converts the interest on our fixed-rate debt to floating. At December 31, 2019, we had $1.5 billion of fixed-to-floating interest rate swaps designated as fair value hedges of long-term debt (effectively converting the fixed-rate debt into floating-rate debt). In late March 2020, we terminated $1 billion of swaps (i.e., two $500 million swaps with maturities in August 2021 and February 2022). As a result, the cumulative basis adjustment on the debt at the time of the terminations (which was equal to the fair value of the swaps at the termination date) will be amortized as an adjustment to interest expense through the maturity of the debt, thereby reducing the effective interest rate. During 2020, $3 million of the outstanding unamortized debt basis adjustment was amortized. We have $12 million of unamortized debt basis adjustments from previously designed fair value hedges remaining. Fair Value Hedges of Assets — During the third quarter of 2020, we began hedging certain newly acquired fixed-rate AFS securities using pay-fixed, receive-floating interest rate swaps, effectively converting the fixed interest income to a floating-rate on the hedged portion of the securities. Subsequently, two of these hedges were slightly restructured to better match the terms of the hedged securities requiring these hedges to be redesignated. Changes in the fair value of the hedged securities prior to the redesignations were recognized in the amortized cost basis of the securities and, similar to the terminated debt hedges noted above, the unamortized basis adjustments will be amortized to interest income through the originally designated maturity of the hedging relationships. Both hedges were designated as hedges of 30-year U.S. Treasury securities and hedged for the full life of the securities. We have $7 million of cumulative unamortized basis adjustments from these previous fair value hedging relationships, which will continue to be amortized as an adjustment to interest income through the end of 2050, thereby increasing the effective interest rate recognized on these securities. As of December 31, 2020, we had qualifying fair value hedging relationships of fixed-rate AFS securities being hedged by pay-fixed, receive-floating interest rate swaps with an aggregate notional amount of $383 million. Cash Flow Hedges — For derivatives designated and qualifying as cash flow hedges, ineffectiveness is not measured or separately disclosed. Rather, as long as the hedging relationship continues to qualify for hedge accounting, the entire change in the fair value of the hedging instrument is recorded in OCI and recognized in earnings as the hedged transaction affects earnings. Derivative amounts affecting earnings are recognized consistent with the classification of the hedged item. We may use interest rate swaps, options, or a combination of options in our cash flow hedging strategy to eliminate or reduce the variable cash flows associated primarily with interest receipts on floating-rate commercial loans due to changes in any separately identifiable and reliably measurable contractual interest rate index. As of December 31, 2020, we had receive-fixed interest rate swaps with an aggregate notional amount of $3.2 billion designated as cash flow hedges of the variability of interest receipts on floating-rate commercial loans due to changes in the LIBOR swap rate. As of December 31, 2020, we had deferred gains in AOCI from active and terminated cash flow hedges of $95 million. Amounts deferred in AOCI from cash flow hedges are expected to be fully reclassified to interest income by the second quarter of 2024. Hedge Effectiveness — We assess the effectiveness of each hedging relationship by comparing the changes in fair value or cash flows on the derivative hedging instrument with the changes in fair value or cash flows on the designated hedged item or transactions for the risk being hedged. If a hedging relationship ceases to qualify for hedge accounting, the relationship is discontinued and future changes in the fair value of the derivative instrument are recognized in current period earnings. For a discontinued or terminated fair value hedging relationship, all remaining basis adjustments to the carrying amount of the hedged item are amortized to interest income or expense over the remaining life of the hedged item consistent with the amortization of other discounts or premiums. Previous balances deferred in AOCI from discontinued or terminated cash flow hedges are reclassified to interest income or expense as the hedged transactions affect earnings or over the originally specified term of the hedging relationship. Collateral and Credit Risk Exposure to credit risk arises from the possibility of nonperformance by counterparties. No significant losses on derivative instruments have occurred during 2020 as a result of counterparty nonperformance. Financial institutions that are well-capitalized and well-established are the counterparties for those derivatives entered into for asset-liability management and used to offset derivatives sold to our customers. We reduce our counterparty exposure for derivative contracts by centrally clearing all eligible derivatives. For those derivatives that are not centrally cleared, the counterparties are typically financial institutions or our customers. For those that are financial institutions, as noted above, we manage our credit exposure through the use of a Credit Support Annex (“CSA”) to an ISDA master agreement with each counterparty. Eligible collateral types are documented by the CSA and controlled under our general credit policies. Collateral balances are typically monitored on a daily basis. A valuation haircut policy reflects the fact that collateral may fall in value between the date the collateral is called and the date of liquidation or enforcement. As of December 31, 2020, all of our collateral held as credit risk mitigation under a CSA is cash. We offer interest rate swaps to our customers to assist them in managing their exposure to changing interest rates. Upon issuance, all of these customer swaps are immediately offset through closely matching derivative contracts, such that we minimize our interest rate risk exposure resulting from such transactions. Most of these customers do not have the capability for centralized clearing. Therefore, we manage the credit risk through loan underwriting that includes a credit risk exposure formula for the swap, the same collateral and guarantee protection applicable to the loan and credit approvals, limits, and monitoring procedures. Fee income from customer swaps is included in other service charges, commissions and fees. Nevertheless, the related credit risk is considered and measured when and where appropriate. Our noncustomer-facing derivative contracts generally require us to pledge collateral for derivatives that are in a net liability position. A certain number of these derivative contracts contain credit-risk-related contingent features that include the requirement to maintain a minimum debt credit rating. We may be required to pledge additional collateral if a credit-risk-related feature were triggered, such as a downgrade of our credit rating. However, in past situations, not all counterparties have demanded that additional collateral be pledged when provided for under their contracts. At December 31, 2020, the fair value of our noncleared (bilateral) derivative liabilities was $418 million, for which we were required to pledge cash collateral of approximately $103 million in the normal course of business. If our credit rating were downgraded one notch by either Standard & Poor’s or Moody’s at December 31, 2020, there would likely be $2 million additional collateral required to be pledged. As a result of the Dodd-Frank Act, all newly eligible derivatives entered into are cleared through a central clearinghouse. Derivatives that are centrally cleared do not have credit-risk-related features that require additional collateral if our credit rating were downgraded. Derivative Amounts Selected information with respect to notional amounts and recorded gross fair values at December 31, 2020, and 2019, and the related gain (loss) of derivative instruments for the years then ended is summarized as follows: December 31, 2020 December 31, 2019 Notional Fair value Notional Fair value (In millions) Other Other Other Other Derivatives designated as hedging instruments: Cash flow hedges of floating-rate assets: Purchased interest rate floors $ — $ — $ — $ — $ — $ — Receive-fixed interest rate swaps 3,150 — — 3,588 — — Fair value hedges: Debt hedges: Receive-fixed interest rate swaps 500 — — 1,500 — — Asset hedges: Pay-fixed interest rate swaps 383 3 — — — — Total derivatives designated as hedging instruments 4,033 3 — 5,088 — — Derivatives not designated as hedging instruments: Customer-facing interest rate derivatives 1, 2 5,986 390 2 4,409 146 5 Offsetting interest rate derivatives 2 5,986 3 409 4,422 5 157 Other interest rate derivatives 1,649 20 3 726 3 1 Foreign exchange derivatives 223 4 4 385 4 4 Total derivatives not designated as hedging instruments 13,844 417 418 9,942 158 167 Total derivatives $ 17,877 $ 420 $ 418 $ 15,030 $ 158 $ 167 1 Customer-facing interest rate derivative fair values include an $18 million and $11 million net credit valuation adjustment as of December 31, 2020, and December 31, 2019, respectively. These adjustments are required to reflect both our nonperformance risk and that of the respective counterparty. 2 The fair value amounts for these derivatives do not include the settlement amounts for those trades that are cleared. Once the settlement amounts with the clearing houses are included the derivative fair values would be the following: December 31, 2020 December 31, 2019 (In millions) Other assets Other liabilities Other assets Other liabilities Customer-facing interest rate derivatives $ 390 $ 2 $ 146 $ 5 Offsetting interest rate derivatives 1 29 — 9 The amount of derivative gains (losses) from cash flow and fair value hedges that was deferred in AOCI or recognized in earnings is summarized as follows: Year Ended December 31, 2020 (In millions) Effective portion of derivative gain/(loss) deferred in AOCI Excluded components deferred in AOCI (amortization approach) Amount of gain/(loss) reclassified from AOCI into income Interest on fair value hedges Hedge ineffectiveness / AOCI reclass due to missed forecast Cash flow hedges of floating-rate assets: 1 Purchased interest rate floors $ — $ — $ 11 $ — $ — Interest rate swaps 101 — 36 — — Fair value hedges of liabilities: Receive-fixed interest rate swaps — — — 6 — Basis amortization on terminated hedges 2, 3 — — — 13 — Fair value hedges of assets: Pay-fixed interest rate swaps — — — (1) — Basis amortization on terminated hedges 2, 3 — — — — — Total derivatives designated as hedging instruments $ 101 $ — $ 47 $ 18 $ — Year Ended December 31, 2019 (In millions) Effective portion of derivative gain/(loss) deferred in AOCI Excluded components deferred in AOCI (amortization approach) Amount of gain/(loss) reclassified from AOCI into income Interest on fair value hedges Hedge ineffectiveness / AOCI reclass due to missed forecast Cash flow hedges of floating-rate assets: 1 Purchased interest rate floors $ — $ 27 $ 3 $ — $ — Interest rate swaps 47 — (7) — — Fair value hedges of liabilities: Receive-fixed interest rate swaps — — — 3 — Basis amortization on terminated hedges 2, 3 — — — — — Fair value hedges of assets: Pay-fixed interest rate swaps — — — — — Basis amortization on terminated hedges 2, 3 — — — — — Total derivatives designated as hedging instruments $ 47 $ 27 $ (4) $ 3 $ — Note: These schedules are not intended to present at any given time our long/short position with respect to our derivative contracts. 1 Amounts recognized in OCI and reclassified from AOCI represent the effective portion of the derivative gain (loss). For the 12 months following December 31, 2020, we estimate that $61 million will be reclassified from AOCI into interest income. 2 Adjustment to interest expense resulting from the amortization of the debt basis adjustment on fixed-rate debt previously hedged by terminated receive-fixed interest rate. 3 The cumulative unamortized basis adjustment from previously terminated or redesignated fair value hedges as of December 31, 2020, is $12 million and $7 million of terminated fair value debt and asset hedges, respectively. The amortization of the cumulative unamortized basis adjustment from asset hedges is not shown in the schedules because it is not significant. The amount of derivative gains (losses) recognized from derivatives not designated in accounting hedges is as follows: Noninterest (Other) Income/(Expense) (In millions) 2020 2019 Derivatives not designated as hedging instruments: Customer-facing interest rate derivatives $ 324 $ 146 Offsetting interest rate derivatives (300) (129) Other interest rate derivatives 8 — Foreign exchange derivatives 21 23 Total derivatives not designated as hedging instruments $ 53 $ 40 The following schedule presents derivatives used in fair value hedge accounting relationships, as well as pre-tax gains/(losses) recorded on such derivatives and the related hedged items for the periods presented. Gain/(loss) recorded in income Twelve Months Ended Twelve Months Ended December 31, 2019 (In millions) Derivatives 2 Hedged items Total income statement impact Derivatives 2 Hedged items Total income statement impact Debt: Receive-fixed interest rate swaps 1,2 $ 63 $ (63) $ — $ 5 $ (5) $ — Assets: Pay-fixed interest rate swaps 1,2 28 (28) — — — — 1 Consists of hedges of benchmark interest rate risk of fixed-rate long-term debt and fixed-rate AFS securities. Gains and losses were recorded in net interest expense or income consistent with the hedged items. 2 The income/expense for derivatives does not reflect interest income/expense from periodic accruals and payments (which are reported above) to be consistent with the presentation of the gains/ (losses) on the hedged items. The following schedule provides selected information regarding the long-term debt in the statement of financial position in which the hedged item is included. Par value of hedged assets/(liabilities) Carrying amount of the hedged assets/(liabilities) Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets/(liabilities) (In millions) 2020 2019 2020 2019 2020 2019 Long-term fixed-rate debt 1,2 $ (500) $ (1,500) $ (537) $ (1,510) $ (37) $ (10) Fixed-rate AFS securities 1,2 383 — 362 — (21) — 1 Carrying amounts displayed above exclude issuance and purchase discounts or premiums and unamortized issuance/acquisition costs. 2 The carrying amount of the hedged items shown above (long-term fixed-rate debt and fixed-rate AFS securities) excludes amounts related to terminated fair value hedges.

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
LEASES	LEASES On January 1, 2019, we adopted ASU 2016-02, Leases (“Topic 842”), which, among other things, requires the recognition of ROU assets and lease liabilities by lessees for those leases classified as operating leases. Upon adoption we elected to use the following optional exemptions that are permitted under Topic 842, which have been applied consistently: • The optional transition method, and there was no impact to retained earnings from recognizing the appropriate amount of lease assets and liabilities on the balance sheet as of the adoption date of the standard. Prior period financial statements were not restated. • The expedient package to not reassess (1) whether any existing or expired contracts are or contain leases, (2) lease classification for any existing or expired leases, and (3) initial direct costs for any existing leases. • To not separate lease components from nonlease components for all classes of underlying assets for lessee or lessor transactions. We determine if a contract is a lease or contains a lease at inception. The right to use leased assets for the lease term are considered ROU assets. Operating lease assets are included in “ Other assets Other liabilities Lease ROU assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. Because most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of future payments. The lease ROU asset also incorporates any amortization incurred, including initial direct costs, and excludes lease incentives received. Our lease terms may include options to extend or terminate the lease, and the lease term incorporates these when it is reasonably certain that we will exercise these options. We enter into certain lease agreements with both lease and nonlease components, which are not separated out for lessees and lessors on a relative standalone basis. We have operating and finance leases for branches, corporate offices, and data centers. Our equipment leases are not material. At December 31, 2020, we had 422 branches, of which 273 are owned and 149 are leased. We lease our headquarters in Salt Lake City, Utah, and other office or data centers are either owned or leased. We may enter into certain lease arrangements with a term of 12 months or less, and we have elected to exclude these from capitalization. The length of our commitments for leases ranges from 2021 to 2063, some of which include options to extend or terminate the leases. As of December 31, 2020, assets recorded under operating leases were $213 million, while assets recorded under finance leases were $4 million. We utilized a secured incremental borrowing rate based on the remaining term of the lease as of the effective date for the discount rate to determine our lease ROU assets and liabilities. The following schedule presents lease-related assets and liabilities, their weighted average remaining life, and the weighted average discount rate. (Dollar amounts in millions) December 31, 2020 December 31, 2019 Operating assets and liabilities Operating right-of-use assets, net of amortization $ 213 $ 218 Operating lease liabilities 240 246 Weighted average remaining lease term (years) Operating leases 8.9 9.1 Finance leases 19.2 20.2 Weighted average discount rate Operating leases 2.9 % 3.2 % Finance leases 3.1 % 3.1 % The components of lease expense are as follows: Year Ended December 31, (In millions) 2020 2019 Operating lease costs $ 49 $ 48 Variable lease costs 49 53 Total lease cost $ 98 $ 101 Supplemental cash flow information related to leases is as follows: Year Ended December 31, (In millions) 2020 2019 Cash paid for amounts in the measurement of lease liabilities: Operating cash disbursements from operating leases $ 51 $ 50 ROU assets obtained in exchange for lease liabilities: Year Ended December 31, (In millions) 2020 2019 New operating lease liabilities $ 9 $ 10 New finance lease liabilities — 6 Total $ 9 $ 16 Maturities analysis for operating lease liabilities as of December 31, 2020 is as follows (contractual undiscounted lease payments): (In millions) Contractual lease payments 2021 $ 49 2022 46 2023 39 2024 30 2025 21 Thereafter 95 Total $ 280 We enter into certain lease agreements where we are the lessor of real estate. Real estate leases are made from bank-owned and subleased property to generate cash flow from the property, including from leasing vacant suites in which we occupy portions of the building. Operating lease income was $12 million for both the years ending 2020 and 2019. We also have a lending division that makes equipment leases, considered to be sales-type leases or direct financing leases, totaling $320 million and $334 million at December 31, 2020 and 2019, respectively. We use leasing of equipment as a venue for customers to access equipment without purchasing upfront. We recorded income of $13 million and $14 million for the years ending 2020 and 2019, respectively.

Premises, Equipment and Softwar

Premises, Equipment and Software, Net	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
PREMISES, EQUIPMENT AND SOFTWARE, NET	. PREMISES, EQUIPMENT AND SOFTWARE, NET Premises, equipment and software, net are summarized as follows: (In millions) December 31, 2020 2019 Land $ 257 $ 235 Buildings 802 747 Furniture and equipment 420 442 Leasehold improvements 165 164 Software 581 507 Total 1 2,225 2,095 Less accumulated depreciation and amortization 1,016 953 Net book value $ 1,209 $ 1,142 1 Amounts include $213 million at December 31, 2020, and $105 million at December 31, 2019, of costs that have been capitalized but are not yet depreciating because the respective assets have not been placed in service.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	GOODWILL AND OTHER INTANGIBLE ASSETS Core deposit and other intangible assets and related accumulated amortization are as follows at December 31: Gross carrying amount Accumulated amortization Net carrying amount (In millions) 2020 2019 2020 2019 2020 2019 Core deposit intangibles $ 167 $ 167 $ (167) $ (167) $ — $ — Customer relationships and other intangibles 30 28 (28) (28) 2 — Total $ 197 $ 195 $ (195) $ (195) $ 2 $ — Changes in the carrying amount of goodwill for operating segments with goodwill are as follows: (In millions) Zions Bank CB&T Amegy Consolidated Bank Balance at December 31, 2018 $ 20 $ 379 $ 615 $ 1,014 Impairment losses — — — — Balance at December 31, 2019 20 379 615 1,014 Impairment losses — — — — Balance at December 31, 2020 $ 20 $ 379 $ 615 $ 1,014 A bank-wide annual impairment test is conducted as of October 1 of each year and updated on a more frequent basis when events or circumstances indicate that impairment could have taken place. Results of the testing for 2020 and 2019 concluded that no impairment was present in any of the operating segments.

Deposits

Deposits	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
DEPOSITS	DEPOSITS At December 31, 2020, the scheduled maturities of all time deposits were as follows: (In millions) Amount 2021 $ 2,239 2022 189 2023 78 2024 42 2025 39 Thereafter 1 Total $ 2,588 The contractual maturities of time deposits with a denomination of $100,000 and over were as follows: (In millions) December 31, 2020 Three months or less $ 274 After three months through six months 204 After six months through twelve months 405 After twelve months 166 Total $ 1,049 Nonbrokered time deposits in denominations that exceed the current FDIC insurance limit of $250,000 were $554 million and $885 million at December 31, 2020 and 2019, respectively. Nonbrokered time deposits at or under $250,000 were $2.0 billion and $1.6 billion at December 31, 2020 and 2019, respectively. Deposit overdrafts reclassified as loan balances were $9 million and $10 million at December 31, 2020 and 2019 , respectively.

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2020
Short-term Debt [Abstract]
SHORT-TERM BORROWINGS	SHORT-TERM BORROWINGS Selected information for FHLB advances and other short-term borrowings is as follows: (Dollar amounts in millions) 2020 2019 2018 Federal Home Loan Bank advances Average amount outstanding $ 206 $ 3,149 $ 2,971 Average rate 1.11 % 2.50 % 2.01 % Highest month-end balance $ 2,200 $ 4,950 $ 5,400 Year-end balance — 1,000 4,500 Average rate on outstanding advances at year-end — % 1.73 % 2.61 % Other short-term borrowings, year-end balances Federal funds purchased $ 1,105 $ 472 $ 541 Security repurchase agreements 406 515 527 Securities sold, not yet purchased 61 66 85 Federal funds purchased and other short-term borrowings $ 1,572 $ 2,053 $ 5,653 We may borrow from the FHLB under their lines of credit that are secured under blanket pledge arrangements. We maintained unencumbered collateral with carrying amounts adjusted for the types of collateral pledged, equal to at least 100% of the outstanding advances. At December 31, 2020, the amount available for FHLB advances was approximately $13.3 billion. We may also borrow from the Federal Reserve based on the amount of collateral pledged to a Federal Reserve Bank. At December 31, 2020, the amount available for Federal Reserve borrowings was approximately $3.8 billion.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2020
Long-term Debt, Unclassified [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Long-term debt is summarized as follows: December 31, (In millions) 2020 2019 Subordinated notes $ 619 $ 572 Senior notes 713 1,147 Finance lease obligations 4 4 Total $ 1,336 $ 1,723 The preceding carrying values represent the par value of the debt adjusted for any unamortized premium or discount, unamortized debt issuance costs, and basis adjustments for interest rate swaps designated as fair value hedges. The change in the outstanding senior debt balance from December 31, 2019 to December 31, 2020 was primarily a result of the repurchase and retirement of senior notes that had adjustments to their carrying values from being in designated hedge relationships with interest rate swaps. During 2020, we repurchased and retired $219 million of senior notes with an interest rate of 3.50% and $210 million of senior notes with an interest rate of 3.35%. During 2020, we terminated two receive-fixed interest rate swaps designated as hedges on senior notes, resulting in one outstanding receive-fixed interest rate swap designated as a hedge on a $500 million subordinated note with an interest rate of 3.25% at December 31, 2020. The outstanding swap constitutes a qualifying fair value hedging relationship. The terminated interest rate swaps adjusted the carrying value of the debt and this adjustment will be amortized into earnings until the original maturity date (see the subsequent Senior Notes schedule). For more information on derivatives designated as qualifying hedges, see Note 7 - Derivative Instruments and Hedging Activities. Subordinated Notes Subordinated notes we issued consist of the following at December 31, 2020: (Dollar amounts in millions) Subordinated notes Coupon rate Balance Par amount Maturity 6.95% $ 87 $ 88 September 2028 3.25% 532 500 October 2029 Total $ 619 $ 588 The 6.95% subordinated notes are unsecured and interest is payable quarterly. The earliest possible redemption date on the 6.95% subordinated notes is September 15, 2023, after which the interest rate changes to an annual floating rate equal to 3mL+3.89%. The 3.25% subordinated notes are unsecured, interest is payable semi-annually, and the earliest possible redemption date is July 29, 2029. Senior Notes Senior notes we issued consist of the following at December 31, 2020: (Dollar amounts in millions) Senior notes Coupon rate Balance Par amount Maturity 4.50% $ 132 $ 132 June 2023 3.50% 285 281 August 2021 3.35% 296 290 March 2022 Total $ 713 $ 703 These notes are unsecured and interest is payable semi-annually. The notes were issued under a shelf registration filed with the Securities and Exchange Commission (“SEC”). The notes are not redeemable prior to maturity. Maturities of Long-term Debt Maturities of long-term debt are as follows for the years succeeding December 31, 2020: (In millions) 2021 $ 282 2022 289 2023 132 2024 — 2025 — Thereafter 585 Total $ 1,288 These maturities do not include the basis adjustments for interest rate swaps designated as fair value hedges.

Shareholders' Equity

Shareholders' Equity	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY Preferred Stock We have 4.4 million authorized shares of preferred stock without par value and with a liquidation preference of $1,000 per share, or $25 per depositary share. Except for Series I and J, all preferred shares were issued in the form of depositary shares, with each depositary share representing a 1/40 th ownership interest in a share of the preferred stock. All preferred shares are registered with the SEC. In addition, Series A, G, and H preferred stock are listed and traded on the NASDAQ Global Select Market. In general, preferred shareholders may receive asset distributions before common shareholders; however, preferred shareholders have only limited voting rights generally with respect to certain provisions of the preferred stock, the issuance of senior preferred stock, and the election of directors. Preferred stock dividends reduce earnings applicable to common shareholders and are paid on the 15th day of the months indicated in the following schedule. Dividends are approved by the Board of Directors. Redemption of the preferred stock is at our option after the expiration of any applicable redemption restrictions and the redemption amount is computed at the per share liquidation preference plus any declared but unpaid dividends. Redemptions are subject to certain regulatory provisions and maintaining well-capitalized minimum requirements. Preferred stock is summarized as follows: Shares at (Dollar amounts in millions) Carrying value at Authorized Outstanding Dividends payable Earliest Rate following earliest redemption date Dividends payable after rate change 2020 2019 (thousands) (thousands) Rate (when applicable) Series A $ 67 $ 67 140,000 66,139 > of 4.0% or 3mL+0.52% Qtrly Mar, Jun, Sep, Dec Dec 15, 2011 Series G 138 138 200,000 138,391 6.3% Qtrly Mar, Jun, Sep, Dec Mar 15, 2023 annual float-ing rate = 3mL+4.24% Series H 126 126 126,221 126,221 5.75% Qtrly Mar, Jun, Sep, Dec Jun 15, 2019 Series I 99 99 300,893 98,555 5.8% Semi-annually Jun, Dec Jun 15, 2023 annual float-ing rate = 3mL+3.8% Qtrly Mar, Jun, Sep, Dec Series J 136 136 195,152 136,368 7.2% Semi-annually Mar, Sep Sep 15, 2023 annual float-ing rate = 3mL+4.44% Qtrly Mar, Jun, Sep, Dec Total $ 566 $ 566 Common Stock Our common stock is traded on the NASDAQ Global Select Market. As of December 31, 2020, there were 164.1 million shares of $0.001 par common stock outstanding. The balance of common stock and additional paid-in-capital was $2.7 billion at December 31, 2020, and decreased $49 million, or 2%, from December 31, 2019 as a result of Bank common stock repurchases. We repurchased 1.7 million shares of common shares outstanding from publicly announced plans during 2020 with a fair value of $75 million at an average price of $45.02 per share. During 2019, we repurchased 23.5 million shares of common shares outstanding from publicly announced plans with a fair value of $1.1 billion at an average price of $46.80 per share. Common Stock Warrants On May 22, 2020, 29.2 million common stock warrants (NASDAQ: ZIONW) expired out-of-the-money. Each common stock warrant was convertible into 1.10 shares at an exercise price of $33.31. Accumulated Other Comprehensive Income Accumulated other comprehensive income improved to $325 million at December 31, 2020 from $43 million at December 31, 2019, primarily as a result of increases in the fair value of AFS securities due to changes in interest rates. Changes in AOCI by component are as follows: (In millions) Net unrealized gains (losses) on investment securities Net unrealized gains (losses) on derivatives and other Pension and post-retirement Total 2020 Balance at December 31, 2019 $ 29 $ 28 $ (14) $ 43 Other comprehensive income (loss) before reclassifications, net of tax 229 77 (9) 297 Amounts reclassified from AOCI, net of tax — (36) 21 (15) Other comprehensive income 229 41 12 282 Balance at December 31, 2020 $ 258 $ 69 $ (2) $ 325 Income tax expense included in other comprehensive income $ 74 $ 13 $ 4 $ 91 2019 Balance at December 31, 2018 $ (228) $ (1) $ (21) $ (250) Other comprehensive income before reclassifications, net of tax 257 24 6 287 Amounts reclassified from AOCI, net of tax — 5 1 6 Other comprehensive income 257 29 7 293 Balance at December 31, 2019 $ 29 $ 28 $ (14) $ 43 Income tax expense included in other comprehensive income $ 84 $ 10 $ 2 $ 96 Statement of Income (SI) (In millions) Amounts reclassified from AOCI 1 Details about AOCI components 2020 2019 2018 Affected line item Net unrealized gains (losses) on derivative instruments $ 47 $ (4) $ (4) SI Interest and fees on loans Income tax expense (benefit) 11 (1) (1) $ 36 $ (3) $ (3) Amortization of net actuarial loss $ (28) $ (2) $ (3) SI Other noninterest expense Income tax benefit (7) (1) (1) $ (21) $ (1) $ (2) 1 Positive reclassification amounts indicate increases to earnings in the statement of income. Deferred Compensation Deferred compensation consists of invested assets, including our common stock, which are held in rabbi trusts for certain employees and directors. The cost of the common stock included in retained earnings was approximately $13 million at both December 31, 2020 and 2019. We consolidate the fair value trust invested assets along with the total obligations and include them in other assets and other liabilities in the balance sheet. At December 31, 2020 and 2019, total invested assets were approximately $120 million and $113 million and total obligations were approximately $133 million and $126 million, respectively.

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2020
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
REGULATORY MATTERS	REGULATORY MATTERSWe are subject to various regulatory capital requirements administered by federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory – and possibly additional discretionary – actions by regulators that, if undertaken, could have a direct material effect on our financial statements. Under capital adequacy guidelines and the regulatory framework for prompt corrective action, we must meet specific capital guidelines that involve quantitative measures of our assets, liabilities, and certain off-balance sheet items as calculated under regulatory accounting practices. Required capital levels are also subject to judgmental review by regulators. In 2013, the FRB, FDIC, and the OCC published final rules (the “Basel III capital rules”) establishing a new comprehensive capital framework for U.S. banking organizations that implemented the Basel Committee on Banking Supervision’s (the “Basel Committee”) December 2010 framework, commonly referred to as Basel III, for strengthening international capital standards as well as certain provisions of the Dodd-Frank Act. The Basel III capital rules became effective for us on January 1, 2015 and were subject to phase-in periods for certain of their components. In November 2017, the FRB, FDIC and OCC published a final rule for nonadvanced approaches banks that extends the regulatory capital treatment applicable during 2017 under the regulatory capital rules for certain items. As a “nonadvanced approaches banking organization,” we made a one-time permanent election to exclude the effects of AOCI items included in capital as allowed under the Basel III capital rules. We met all capital adequacy requirements under the Basel III capital rules as of December 31, 2020. Quantitative measures established by regulation to ensure capital adequacy require us to maintain minimum amounts and ratios of Total and Tier 1 capital (as defined in the regulations) to risk-weighted assets (as defined), and of Tier 1 capital (as defined) to average assets (as defined). “Well-capitalized” levels are also published as a guideline to evaluate capital positions. As of December 31, 2020, all our capital ratios exceeded the “well-capitalized” levels under the regulatory framework for prompt corrective action. Dividends declared by us in any calendar year may not, without the approval of the appropriate federal regulators, exceed specified criteria. When determining dividends, we consider current and historical earning levels, retained earnings, and risk-based and other regulatory capital requirements and limitations. Bank-run stress tests seek to comprehensively measure all risks to which the institution is exposed, including credit, liquidity, market, operating and other risks, the losses that could result from those risk exposures under adverse scenarios, and the institution’s resulting capital levels. These stress tests have both a qualitative and a quantitative component. The qualitative component evaluates the robustness of our risk identification, stress risk modeling, policies, capital planning, governance processes, and other components of a Capital Adequacy Process. The quantitative process subjects our balance sheet and other risk characteristics to stress testing by using our own models. Our capital amounts and ratios at December 31, 2020 and 2019 under Basel III are as follows: (Dollar amounts in millions) December 31, 2020 To be well-capitalized Amount Ratio Amount Ratio Basel III Regulatory Capital Amounts and Ratios Total capital (to risk-weighted assets) $ 7,862 14.1 % $ 5,587 10.0 % Tier 1 capital (to risk-weighted assets) 6,579 11.8 4,469 8.0 Common equity tier 1 capital (to risk-weighted assets) 6,013 10.8 3,631 6.5 Tier 1 capital (to average assets) 6,579 8.3 3,944 5.0 December 31, 2019 To be well-capitalized (Dollar amounts in millions) Amount Ratio Amount Ratio Basel III Regulatory Capital Amounts and Ratios Total capital (to risk-weighted assets) $ 7,411 13.2 % $ 5,604 10.0 % Tier 1 capital (to risk-weighted assets) 6,285 11.2 4,483 8.0 Common equity tier 1 capital (to risk-weighted assets) 5,719 10.2 3,643 6.5 Tier 1 capital (to average assets) 6,285 9.2 3,426 5.0 We are also subject to “capital conservation buffer” regulatory requirements. At December 31, 2020, the Basel III capital rules also require us to maintain a 2.5% “capital conservation buffer” designed to absorb losses during periods of economic stress, composed entirely of Common Equity Tier 1 (“CET1”), on top of the minimum risk-weighted asset ratios, effectively resulting in minimum ratios of (1) CET1 to risk-weighted assets of at least 7.0%, (2) Tier 1 capital to risk-weighted assets of at least 8.5%, and (3) Total capital to risk-weighted assets of at least 10.5%. Banking institutions with a ratio of CET1 to risk-weighted assets above the minimum but below the capital conservation buffer will face constraints on dividends, equity repurchases, and compensation based on the amount of the shortfall. Our internal triggers and limits under actual conditions and baseline projections are more restrictive than the capital conservation buffer requirements. A final rule adopted by the federal banking agencies in February 2019 provides banking organizations with the option to phase in, over a three-year period, the adverse day-one regulatory capital effects of the adoption of CECL. On March 27, 2020, the federal banking agencies issued an interim final rule that gives banking organizations that implement CECL before the end of 2020 the option to reduce for two years a portion of CECL’s adverse effect on regulatory capital. This is in addition to the three-year transition period already in place, resulting in an optional five-year transition. We adopted the provisions of this guidance beginning with the first quarter 2020 financial statements. As a result, we will delay recognizing the December 31, 2020 impact of the ACL on regulatory capital until after a two-year deferral period, which for us extends through December 31, 2021. Beginning on January 1, 2022, we will be required to phase in 25% of the previously deferred estimated capital impact of the ACL, with an additional 25% to be phased in at the beginning of each subsequent year until fully phased in by the first quarter of 2025. At December 31, 2020, the application of these provisions improved our CET1, Tier 1 risk-based and Total risk-based capital ratios by 10 bps each, and our Tier 1 leverage capital ratio by 6 bps. The schedule below presents our actual capital ratios in comparison to minimum capital ratios and capital ratios in excess of minimum capital requirements plus minimum capital conservation buffer requirements. December 31, 2020 Actual Capital Ratio Minimum Capital Ratio Capital Conservation Buffer Ratio Capital Ratio in Excess of Minimum Capital Ratio plus Capital Conservation Buffer Requirement Total capital (to risk-weighted assets) 14.1 % 8.0 % 2.5 % 3.6 % Tier 1 capital (to risk-weighted assets) 11.8 6.0 2.5 3.3 Common equity tier 1 capital (to risk-weighted assets) 10.8 4.5 2.5 3.8

Commitments, Guarantees, Contin

Commitments, Guarantees, Contingent Liabilities, and Related Parties	12 Months Ended
	Dec. 31, 2020
Guarantees, Commitments And Contingencies [Abstract]
COMMITMENTS, GUARANTEES, CONTINGENT LIABILITIES, AND RELATED PARTIES	COMMITMENTS, GUARANTEES, CONTINGENT LIABILITIES, AND RELATED PARTIES Commitments and Guarantees We use certain financial instruments, including derivative instruments, in the normal course of business to meet the financing needs of our customers, to reduce our own exposure to fluctuations in interest rates, and to make a market in U.S. government, agency, corporate, and municipal securities. These financial instruments involve, to varying degrees, elements of credit, liquidity, and interest rate risk in excess of the amounts recognized in the balance sheet. Derivative instruments are described in Notes 7 and 3. Contractual amounts of the off-balance sheet financial instruments used to meet the financing needs of our customers are as follows: December 31, (In millions) 2020 2019 Net unfunded commitments to extend credit 1 $ 24,217 $ 23,099 Standby letters of credit: Financial 531 631 Performance 167 192 Commercial letters of credit 34 5 Total unfunded lending commitments $ 24,949 $ 23,927 1 Net of participations. Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Commitments generally have fixed expiration dates or other termination clauses and may require the payment of a fee. The amount of collateral obtained, if deemed necessary by us upon extension of credit, is based on our initial credit evaluation of the counterparty. Types of collateral vary, but may include accounts receivable, inventory, property, plant and equipment, and income-producing properties. While establishing commitments to extend credit creates credit risk, a significant portion of such commitments is expected to expire without being drawn upon. As of December 31, 2020, $7.7 billion of commitments expire in 2021. We use the same credit policies and procedures in making commitments to extend credit and conditional obligations as we do for on-balance sheet instruments. These policies and procedures include credit approvals, limits, and monitoring. We issue standby and commercial letters of credit as conditional commitments generally to guarantee the performance of a customer to a third party. The guarantees are primarily issued to support public and private borrowing arrangements, including commercial paper, bond financing, and similar transactions. Standby letters of credit include remaining commitments of $398 million expiring in 2021 and $300 million expiring thereafter through 2030. The credit risk involved in issuing letters of credit is essentially the same as that involved in extending loan facilities to customers. We generally hold marketable securities and cash equivalents as collateral when necessary. At December 31, 2020, we had recorded $6 million as a liability for these guarantees, which consisted of $4 million attributable to the RULC and $2 million of deferred commitment fees. Certain mortgage loans sold have limited recourse provisions for periods ranging from three months to one year. The amount of losses resulting from the exercise of these provisions has not been significant. The contractual or notional amount of financial instruments indicates a level of activity associated with a particular financial instrument class and is not a reflection of the actual level of risk. As of December 31, 2020 and 2019, the regulatory risk-weighted values assigned to all off-balance sheet financial instruments and derivative instruments described herein were $8.5 billion and $8.3 billion, respectively. At December 31, 2020, we were not required to maintain any cash balances with the Federal Reserve Bank to meet minimum balance requirements in accordance with FRB regulations. Contingent Liabilities and Legal Matters We are subject to litigation in court and arbitral proceedings, as well as proceedings, investigations, examinations and other actions brought or considered by governmental and self-regulatory agencies. Litigation may relate to lending, deposit and other customer relationships, vendor and contractual issues, employee matters, intellectual property matters, personal injuries and torts, regulatory and legal compliance, and other matters. While most matters relate to individual claims, we are also subject to putative class action claims and similar broader claims. Proceedings, investigations, examinations and other actions brought or considered by governmental and self-regulatory agencies may relate to our banking, investment advisory, trust, securities, and other products and services; our customers’ involvement in money laundering, fraud, securities violations and other illicit activities or our policies and practices relating to such customer activities; and our compliance with the broad range of banking, securities and other laws and regulations applicable to us. At any given time, we may be in the process of responding to subpoenas, requests for documents, data and testimony relating to such matters and engaging in discussions to resolve the matters. As of December 31, 2020, we were subject to the following material litigation or governmental inquiries: • a civil suit, JTS Communities, Inc. et. al v. CB&T, Jun Enkoji and Dawn Satow , brought against us in the Superior Court for Sacramento County, California in June 2017. In this case four investors in our former customer, International Manufacturing Group (“IMG”) seek to hold us liable for losses arising from their investments in that company, alleging that we conspired with and knowingly assisted IMG and its principal in furtherance of an alleged Ponzi scheme. This case is in the discovery phase with dispositive motion practice having been completed. Trial is scheduled for the first quarter of 2021. • a civil class action lawsuit, Evans v. CB&T , brought against us in the United States District Court for the Eastern District of California in May 2017. This case was filed on behalf of a class of up to 50 investors in IMG and seeks to hold us liable for losses of class members arising from their investments in IMG, alleging that we conspired with and knowingly assisted IMG and its principal in furtherance of an alleged Ponzi scheme. In December 2017, the District Court dismissed all claims against us. In January 2018, the plaintiff filed an appeal with the Court of Appeals for the Ninth Circuit. The appeal was heard in early April 2019 with the Court of Appeals reversing the trial court’s dismissal. This case is in the post-pleading phase and trial will not occur for a substantial period of time. • two civil cases, Lifescan Inc. and Johnson & Johnson Health Care Services v. Jeffrey Smith, et. al. , brought against us in the United States District Court for the District of New Jersey in December 2017, and Roche Diagnostics and Roche Diabetes Care Inc. v. Jeffrey C. Smith, et. al. , brought against us in the United States District Court for the District of New Jersey in March 2019. In these cases, certain manufacturers and distributors of medical products seek to hold us liable for allegedly fraudulent practices of our borrower who filed for bankruptcy protection in 2017. The cases are in early phases, with initial motion practice and discovery underway in the Lifescan case. Trial has not been scheduled in either case. • a civil class action lawsuit, Gregory, et. al. v. Zions Bancorporation , brought against us in the United States District Court in Utah in January 2019. This case was filed on behalf of investors in Rust Rare Coin, Inc., alleging that we aided and abetted a Ponzi scheme fraud perpetrated by Rust Rare Coin, a Zions Bank customer. The case follows civil actions and the establishment of a receivership for Rust Rare Coin by The Commodities Futures Trading Commission and the Utah Division of Securities in November 2018, as well as a separate suit brought by the SEC against Rust Rare Coin and its principal, Gaylen Rust. During the third quarter of 2020, the Court granted our motion to dismiss the plaintiffs' claims in part, dismissing claims relating to fraud and fiduciary duty, but allowing a claim for aiding and abetting conversion to proceed. The case is in the early discovery phase. Trial has not been scheduled. During the third quarter of 2020, the plaintiffs in three civil class action lawsuits, Fahmia Inc. v Zions Bancorporation, et. al., ImpAcct LLC v. JPMorgan Chase, et. al., and Manoloff v. Bank of America, et. al. , voluntarily agreed to dismiss their actions against us. These cases alleged that we wrongly failed to pay agents of borrowers receiving loans from us under the Government's Paycheck Protection Program fees that were allegedly owed to them under the program. At least quarterly, we review outstanding and new legal matters, utilizing then available information. In accordance with applicable accounting guidance, if we determine that a loss from a matter is probable and the amount of the loss can be reasonably estimated, we establish an accrual for the loss. In the absence of such a determination, no accrual is made. Once established, accruals are adjusted to reflect developments relating to the matters. In our review, we also assess whether we can determine the range of reasonably possible losses for significant matters in which we are unable to determine that the likelihood of a loss is remote. Because of the difficulty of predicting the outcome of legal matters, described subsequently, we are able to meaningfully estimate such a range only for a limited number of matters. Based on information available as of December 31, 2020, we estimated that the aggregate range of reasonably possible losses for those matters to be from $0 million to roughly $35 million in excess of amounts accrued. The matters underlying the estimated range will change from time to time, and actual results may vary significantly from this estimate. Those matters for which a meaningful estimate is not possible are not included within this estimated range and, therefore, this estimated range does not represent our maximum loss exposure. Based on our current knowledge, we believe that our current estimated liability for litigation and other legal actions and claims, reflected in our accruals and determined in accordance with applicable accounting guidance, is adequate and that liabilities in excess of the amounts currently accrued, if any, arising from litigation and other legal actions and claims for which an estimate as previously described is possible, will not have a material impact on our financial condition, results of operations, or cash flows. However, in light of the significant uncertainties involved in these matters, and the very large or indeterminate damages sought in some of these matters, an adverse outcome in one or more of these matters could be material to our financial condition, results of operations, or cash flows for any given reporting period. Any estimate or determination relating to the future resolution of litigation, arbitration, governmental or self-regulatory examinations, investigations or actions or similar matters is inherently uncertain and involves significant judgment. This is particularly true in the early stages of a legal matter, when legal issues and facts have not been well articulated, reviewed, analyzed, and vetted through discovery, preparation for trial or hearings, substantive and productive mediation or settlement discussions, or other actions. It is also particularly true with respect to class action and similar claims involving multiple defendants, matters with complex procedural requirements or substantive issues or novel legal theories, and examinations, investigations and other actions conducted or brought by governmental and self-regulatory agencies, in which the normal adjudicative process is not applicable. Accordingly, we usually are unable to determine whether a favorable or unfavorable outcome is remote, reasonably likely, or probable, or to estimate the amount or range of a probable or reasonably likely loss, until relatively late in the course of a legal matter, sometimes not until a number of years have elapsed. Accordingly, our judgments and estimates relating to claims will change from time to time in light of developments and actual outcomes will differ from our estimates. These differences may be material. Related Party Transactions We have no material related party transactions requiring disclosure. In the ordinary course of business, we extend credit to related parties, including executive officers, directors, principal shareholders, and their associates and related interests. These related party loans are made in compliance with applicable banking regulations.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2020
Revenue Recognition and Deferred Revenue [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION Adoption of ASC Topic 606, “ Revenue from Contracts with Customers ” On January 1, 2018, we adopted the accounting guidance in ASC Topic 606, “ Revenue from Contracts with Customers ” (“ASC 606”) using the modified retrospective method applied to those contracts with customers for which the performance obligations were not completed as of January 1, 2018. Upon adoption, we elected to use the following optional exemptions that are permitted under the ASC 606, which have been applied consistently to all contracts within all reporting periods presented: • We recognize the incremental cost of obtaining a contract as an expense, when incurred, if the amortization period of the asset that we would have recognized is one year or less. • For performance obligations satisfied over time, if we have a right to consideration from a customer in an amount that corresponds directly with the value to the customer of our performance completed to date, we will generally recognize revenue in the amount to which we have a right to invoice. • We do not generally disclose information about our remaining performance obligations for those performance obligations that have an original expected duration of one year or less, or where we recognize revenue in the amount to which we have a right to invoice. Revenue Recognition We derive our revenue primarily from interest income on loans and securities, which was more than three-quarters of our revenue for 2020. Only noninterest income is considered to be revenue from contracts with customers in scope of ASC 606. Revenue from contracts with customers is recognized when control of the promised goods or services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. The following is a description of revenue from contracts with customers: Commercial account fees Commercial account fee income is comprised of account analysis fees, merchant fees, and payroll services income. Revenue is recognized as the services are rendered or upon completion of services. Card fees Our card fee income includes interchange income from credit and debit cards, net fees earned from processing card transactions for merchants, and automated teller machine (“ATM”) services. Card income is recognized as earned. Reward program costs are recorded when the rewards are earned by the customer and presented as a reduction to interchange income. Retail and business banking fees Retail and business banking fees typically consist of fees charged for providing customers with deposit services. These fees are primarily comprised of insufficient funds fees, noncustomer ATM charges, and other various fees on deposit accounts. Service charges on deposit accounts include fees earned in lieu of compensating balances, and fees earned for performing cash management services and other deposit account services. Service charges on deposit accounts in this revenue category are recognized over the period in which the related service is provided. Treasury Management fees are billed monthly based on services rendered for the month. Loan-related fees and income Loan-related fees and income consist of servicing and sales income on loan accounts as well as other miscellaneous loan-related fees. Service charges on loan accounts are recognized over the period in which the related service is provided, when the service is rendered, or upon completion of the service. Capital markets and foreign exchange fees Capital markets and foreign exchange fees primarily consist of mutual fund distribution fees, municipal advisory services, customer swap fees, loan syndication fees, and foreign exchange services provided to customers. Revenue is recognized as the services are rendered or upon completion of services. Wealth management and trust fees Wealth management and trust fees are primarily comprised of personal trust income and wealth management commissions, but also are made up of other products such as corporate trust income, portfolio services, and advisory services. Revenue is recognized as the services are rendered or upon completion of services. Financial planning and estate services typically have performance obligations that are greater than 12 months, although the amount of future performance obligations are not significant. Other customer-related fees Other customer-related fees consist of miscellaneous income streams, including claims and inventory management services for certain customers. Revenue is recognized as the services are rendered or upon completion of services. Disaggregation of Revenue We provide services across different geographic areas, primarily in 11 Western U.S. States, under banking operations that have their own individual brand names, including Zions Bank, Amegy Bank, California Bank & Trust, National Bank of Arizona, Nevada State Bank, Vectra Bank Colorado, and The Commerce Bank of Washington. The operating segment listed as “Other” includes certain nonbank financial services subsidiaries, centralized back-office functions, and eliminations of transactions between the segments. Certain prior period amounts have been reclassified to conform with the current period presentation. These reclassifications did not affect net income or shareholders’ equity. The following schedule presents noninterest income and net revenue by operating segments: Zions Bank Amegy CB&T (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Commercial account fees $ 42 $ 41 $ 41 $ 37 $ 34 $ 34 $ 22 $ 23 $ 23 Card fees 49 51 50 24 28 29 14 16 15 Retail and business banking fees 21 23 24 15 17 16 11 13 14 Capital markets and foreign exchange fees (1) — — 5 6 6 — — — Wealth management and trust fees 23 17 16 16 12 10 8 4 4 Other customer-related fees 2 2 3 1 1 1 1 2 2 Total noninterest income from contracts with customers (ASC 606) 136 134 134 98 98 96 56 58 58 Other noninterest income (Non-ASC 606 customer related) 23 12 12 34 40 30 36 28 22 Total customer-related fees 159 146 146 132 138 126 92 86 80 Other noninterest income (noncustomer-related) (1) 1 1 1 — — 3 2 2 Total noninterest income 158 147 147 133 138 126 95 88 82 Other real estate owned income — 3 1 — — — 1 — — Net interest income 650 688 662 485 489 485 512 512 508 Total income less interest expense $ 808 $ 838 $ 810 $ 618 $ 627 $ 611 $ 608 $ 600 $ 590 NBAZ NSB Vectra (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Commercial account fees $ 7 $ 7 $ 7 $ 8 $ 8 $ 9 $ 6 $ 6 $ 6 Card fees 9 11 11 10 12 12 5 6 6 Retail and business banking fees 8 8 9 9 11 10 4 5 4 Capital markets and foreign exchange fees — — — — — — — — — Wealth management and trust fees 3 2 2 3 3 3 4 2 2 Other customer-related fees 1 1 1 1 1 1 — — — Total noninterest income from contracts with customers (ASC 606) 28 29 30 31 35 35 19 19 18 Other noninterest income (Non-ASC 606 customer related) 12 12 9 12 8 6 13 7 6 Total customer-related fees 40 41 39 43 43 41 32 26 24 Other noninterest income (noncustomer-related) 1 1 — — — — — — — Total noninterest income 41 42 39 43 43 41 32 26 24 Other real estate owned income — — — — 1 — — — — Net interest income 216 223 216 146 148 142 135 135 130 Total income less interest expense $ 257 $ 265 $ 255 $ 189 $ 192 $ 183 $ 167 $ 161 $ 154 TCBW Other Consolidated Bank (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Commercial account fees $ 1 $ 2 $ 2 $ 2 $ — $ — $ 125 $ 121 $ 122 Card fees 1 1 2 1 2 — 113 127 125 Retail and business banking fees — — — — 1 1 68 78 78 Capital markets and foreign exchange fees — — — 8 7 6 12 13 12 Wealth management and trust fees 1 1 — 1 16 14 59 57 51 Other customer-related fees — — — 19 11 16 25 18 24 Total noninterest income from contracts with customers (ASC 606) 3 4 4 31 37 37 402 414 412 Other noninterest income (Non-ASC 606 customer related) 2 1 1 15 3 10 147 111 96 Total customer-related fees 5 5 5 46 40 47 549 525 508 Other noninterest income (noncustomer-related) — — — 21 33 41 25 37 44 Total noninterest income 5 5 5 67 73 88 574 562 552 Other real estate owned income — — — — — — 1 4 1 Net interest income 52 53 52 20 24 35 2,216 2,272 2,230 Total income less interest expense $ 57 $ 58 $ 57 $ 87 $ 97 $ 123 $ 2,791 $ 2,838 $ 2,783 Revenue from contracts with customers did not generate significant contract assets and liabilities. Contract receivables are included in Other Assets. Payment terms vary by services offered, and the timing between completion of performance obligations and payment is typically not significant.

Retirement Plans

Retirement Plans	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Retirement Plans	RETIREMENT PLANS Defined Benefit Plans Pension — In October 2018, we announced our intention to terminate our defined benefit pension plan, subject to obtaining necessary regulatory approval. We received an IRS letter of determination on March 31, 2020. Plan participants made elections for lump-sum distributions or annuity benefits. Lump-sum distributions were completed in May 2020, and the annuity purchase was completed in June 2020. As a result of the pension termination, we incurred $28 million of expense, which was recognized in Other noninterest expense. Supplemental Retirement — These unfunded, nonqualified plans are for certain current and former employees. Each year, our contributions to these plans are made in amounts sufficient to meet benefit payments to plan participants. Post-retirement Medical/Life — This unfunded health care and life insurance plan provides post-retirement medical benefits to certain former full-time employees who meet minimum age and service requirements. The plan also provides specified life insurance benefits to certain employees. The plan is contributory with retiree contributions adjusted annually, and contains other cost-sharing features such as deductibles and coinsurance. Plan coverage is provided by self-funding or health maintenance organization options. Our contribution toward the retiree medical premium has been permanently frozen at an amount that does not increase in any future year. Retirees pay the difference between the full premium rates and our capped contribution. Because our contribution rate is capped, there is no effect on the post-retirement plan from assumed increases or decreases in health care cost trends. Each year, our contributions to the plan are made in amounts sufficient to meet the portion of the premiums that are our responsibility. The following schedule presents the change in benefit obligation, change in fair value of plan assets, and funded status, of the plans and amounts recognized in the balance sheet as of the measurement date of December 31: Pension Supplemental Post-retirement (In millions) 2020 2019 2020 2019 2020 2019 Change in benefit obligation: Benefit obligation at beginning of year $ 140 $ 138 $ 8 $ 9 $ 1 $ 1 Interest cost 1 5 — — — — Actuarial loss 13 8 1 — — — Annuity purchase (97) — — — — — Benefits paid (57) (11) (1) (1) — — Benefit obligation at end of year — 140 8 8 1 1 Change in fair value of plan assets: Fair value of plan assets at beginning of year 171 157 — — — — Actual return on plan assets 4 25 — — — — Employer contributions (21) — 1 1 — — Annuity purchase (97) — — — — — Benefits paid (57) (11) (1) (1) — — Fair value of plan assets at end of year — 171 — — — — Funded status $ — $ 31 $ (8) $ (8) $ (1) $ (1) Amounts recognized in balance sheet: Asset (liability) for pension/postretirement benefits $ — $ 31 $ (8) $ (8) $ (1) $ (1) Accumulated other comprehensive income (loss) — (17) (3) (2) — — The pension asset and the liability for supplemental retirement and post-retirement benefits are included in other assets and other liabilities, respectively, in the balance sheet. The accumulated benefit obligation is the same as the benefit obligation shown in the preceding schedule. The following schedule presents the components of net periodic benefit cost (credit) for the plans: Pension Supplemental Post-retirement (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Interest cost $ 1 $ 5 $ 6 $ — $ — $ — $ — $ — $ — Expected return on plan assets (2) (9) (11) — — — — — — Amortization of net actuarial loss — — 1 — — — — — — Settlement loss 28 1 1 — — — — — — Net periodic benefit cost $ 27 $ (3) $ (3) $ — $ — $ — $ — $ — $ — Weighted average assumptions based on the pension plan are the same where applicable for each of the plans and are as follows: 2020 2019 2018 Used to determine benefit obligation at year-end: Discount rate 1.85 % 3.20 % 4.20 % Used to determine net periodic benefit cost for the years ended December 31: Discount rate NA 4.20 3.50 Expected long-term return on plan assets NA 5.25 5.75 The discount rate reflects the yields available on long-term, high-quality fixed-income debt instruments with cash flows similar to the obligations of the pension plan, and is reset annually on the measurement date. The expected long-term rate of return on plan assets is based on a review of the target asset allocation of the plan. This rate is intended to approximate the long-term rate of return that we anticipate receiving on the plan’s investments, considering the mix of the assets that the plan holds as investments, the expected return on these underlying investments, the diversification of these investments, and the rebalancing strategies employed. An expected long-term rate of return is assumed for each asset class and an underlying inflation rate assumption is determined. Benefit payments to the plans’ participants are estimated in the following schedule for the years succeeding December 31, 2020. (In millions) Supplemental Post-retirement 2021 $ 2 $ — 2022 1 — 2023 1 — 2024 1 — 2025 1 — Years 2026 – 2030 2 — We are obligated under supplemental retirement plans for certain current and former employees. Our liability for these plans was $5 million at both December 31, 2020 and 2019. As of December 31, 2019, pension plan investments valued using NAV as the practical expedient for fair value consist of $166 million in debt investments in pooled separate accounts. These funds are invested in by more than one investor. They are offered through separate accounts of the trustee’s insurance company and managed by internal and professional advisors. Participation units in these accounts are valued at the NAV as the practical expedient for fair value as determined by the insurance company. The following presents additional information as of December 31, 2019 for the pooled separate accounts and limited partnerships whose fair values under Levels 2 and 3 are based on NAV per share: Investment Unfunded commitments (in millions, approximately) Redemption Frequency Notice period Pooled separate accounts NA Daily < $1 million, 1 day The following reconciles the beginning and ending balances of assets measured at fair value on a recurring basis using Level 3 inputs: Guaranteed deposit account Year Ended December 31, (In millions) 2020 2019 Balance at beginning of year $ 5 $ 12 Purchases 151 4 Sales (156) (11) Balance at end of year $ — $ 5 Defined Contribution Plan We offer a 401(k) and employee stock ownership plan under which employees select from several investment alternatives. Employees can contribute up to 80% of their earnings subject to the annual maximum allowed contribution. We match 100% of the first 3% of employee contributions and 50% of the next 3% of employee contributions. Matching contributions to participants, which were shares of our common stock purchased in the open market, amounted to $31 million, $33 million, and $29 million in 2020 , 2019, and 2018 respectively. The 401(k) plan also has a noncontributory profit-sharing feature which is discretionary and may range from 0% to 3.5% of eligible compensation based upon our return on average common equity for the year. The profit-sharing expense was $7 million, $16 million, and $17 million in 2020 , 2019 , and 2018, respectively. The profit-sharing contribution to participants consisted of shares of our common stock purchased in the open market.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION	SHARE-BASED COMPENSATION We have a share-based compensation incentive plan which allows us to grant stock options, restricted stock, RSUs, and other awards to employees and nonemployee directors. Total shares authorized under the plan were 9,000,000 at December 31, 2020, of which 2,786,162 were available for future grants. All share-based payments to employees, including grants of employee stock options, are recognized in the statement of income based on their grant date values. The value of an equity award is estimated on the grant date using a fair value-based model without regard to service or performance vesting conditions, but does consider post-vesting restrictions. We classify all share-based awards as equity instruments. Compensation expense is included in salaries and employee benefits in the statement of income, with the corresponding increase included in additional paid-in capital. We account for forfeitures of share-based compensation awards as they occur. Substantially all awards of stock options, restricted stock, and RSUs have graded vesting that is recognized on a straight-line basis over the vesting period. Compensation expense and the related tax benefit for all share-based awards were as follows: (In millions) 2020 2019 2018 Compensation expense $ 26 $ 27 $ 26 Reduction of income tax expense 8 11 14 We reduced share-based compensation expense by $1 million during 2020, 2019, and 2018, respectively, as a result of using a valuation model to estimate a liquidity discount on RSUs with post-vesting restrictions. As of December 31, 2020, compensation expense not yet recognized for nonvested share-based awards was approximately $27 million, which is expected to be recognized over a weighted average period of 2.4 years. Stock Options Stock options granted to employees generally vest at the rate of one third each year and expire seven years after the date of grant. For all stock options granted in 2020, 2019, and 2018, we used the Black-Scholes option pricing model to estimate the grant date value of stock options in determining compensation expense. The following summarizes the weighted average value at grant date and the significant assumptions used in applying the Black-Scholes model for options granted: 2020 2019 2018 Weighted average value for options granted $ 8.18 $ 10.30 $ 12.64 Weighted average assumptions used: Expected dividend yield 3.0 % 2.5 % 2.0 % Expected volatility 27.0 % 26.0 % 27.5 % Risk-free interest rate 1.38 % 2.52 % 2.62 % Expected life (in years) 5.0 5.0 5.0 The assumptions for expected dividend yield, expected volatility, and expected life reflect management’s judgment and include consideration of historical experience. Expected volatility is based in part on historical volatility. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. The following summarizes our stock option activity for the three years ended December 31, 2020: Number of shares Weighted average exercise price Balance at December 31, 2017 2,560,571 $ 27.06 Granted 194,001 55.13 Exercised (729,346) 26.79 Expired (2,000) 25.74 Forfeited (18,628) 31.11 Balance at December 31, 2018 2,004,598 29.85 Granted 256,818 50.80 Exercised (569,808) 24.61 Expired (4,330) 22.37 Forfeited (10,500) 43.13 Balance at December 31, 2019 1,676,778 34.77 Granted 320,913 45.61 Exercised (285,954) 26.48 Expired (22,685) 30.17 Forfeited (5,395) 51.34 Balance at December 31, 2020 1,683,657 38.26 Outstanding stock options exercisable as of: December 31, 2020 1,137,596 $ 33.42 December 31, 2019 1,239,821 28.95 December 31, 2018 1,448,244 26.68 We issue new authorized common shares for the exercise of stock options. The total intrinsic value of stock options exercised was approximately $3 million in 2020, $13 million in 2019, and $20 million in 2018. Cash received from the exercise of stock options was $7 million in 2020, $13 million in 2019, and $18 million in 2018. Additional selected information on stock options at December 31, 2020 follows: Outstanding stock options Exercisable stock options Exercise price range Number of shares Weighted average exercise price Weighted average remaining contractual life (years) Number of shares Weighted average exercise price $4.15 to $19.99 10,867 $ 6.22 1 10,867 $ 6.22 $20.00 to $24.99 276,809 21.03 2.1 276,809 21.03 $25.00 to $29.99 450,709 28.53 1.1 450,031 28.53 $30.00 to $39.99 22,225 30.10 0.4 22,225 30.10 $40.00 to $44.99 173,351 44.10 3.0 171,290 44.12 $45.00 to $49.99 318,954 45.65 6.1 — — $50.00 to $55.68 430,742 52.90 4.5 206,374 53.58 1,683,657 38.26 1 3.3 1,137,596 33.42 1 The weighted average remaining contractual life excludes 10,867 stock options without a fixed expiration date that were assumed with the Amegy acquisition. They expire between the date of termination and one year from the date of termination, depending upon certain circumstances. The aggregate intrinsic value of outstanding and exercisable stock options at December 31, 2020 and 2019 was $14 million and $29 million, respectively. For exercisable options, the weighted average remaining contractual life was 2.2 years and 2.4 years at December 31, 2020 and 2019, respectively, excluding the stock options previously noted without a fixed expiration date. At December 31, 2020, 546,061 stock options with a weighted average exercise price of $48.34, a weighted average remaining life of 5.5 years, and an aggregate intrinsic value of $12 thousand, were expected to vest. Restricted Stock and Restricted Stock Units Restricted stock is common stock with certain restrictions that relate to trading and the possibility of forfeiture. Generally, restricted stock vests over four years. Holders of restricted stock have full voting rights and receive dividend equivalents during the vesting period. In addition, holders of restricted stock can make an election to be subject to income tax on the grant date rather than the vesting date. RSUs represent rights to one share of common stock for each unit and generally vest over four years. Holders of RSUs receive dividend equivalents during the vesting period, but do not have voting rights. Compensation expense is determined based on the number of restricted shares or RSUs granted and the market price of our common stock at the issue date. During 2020, 2019, and 2018, we granted 28,992, 19,116, and 14,796 RSUs, respectively, to nonemployee directors. The RSUs vested immediately upon grant. The following summarizes our restricted stock activity for the three years ended December 31, 2020: Number of shares Weighted average fair value Nonvested restricted shares at December 31, 2017 38,978 $ 25.91 Issued 21,634 42.90 Vested (14,836) 26.27 Forfeited (90) 55.68 Nonvested restricted shares at December 31, 2018 45,686 33.78 Issued 24,994 42.83 Vested (20,223) 30.69 Nonvested restricted shares at December 31, 2019 50,457 39.50 Issued 27,798 45.65 Vested (20,859) 34.77 Nonvested restricted shares at December 31, 2020 57,396 44.20 The following summarizes our RSU activity for the three years ended December 31, 2020: Number of restricted stock units Weighted average fair value Restricted stock units at December 31, 2017 1,709,813 $ 30.08 Granted 461,305 53.17 Vested (699,920) 29.56 Forfeited (70,499) 35.95 Restricted stock units at December 31, 2018 1,400,699 37.65 Granted 536,489 47.85 Vested (614,968) 33.74 Forfeited (28,150) 44.69 Restricted stock units at December 31, 2019 1,294,070 43.59 Granted 586,302 42.75 Vested (593,375) 37.56 Forfeited (44,676) 47.78 Restricted stock units at December 31, 2020 1,242,321 46.31 The total value at grant date of restricted stock and RSUs vested during the year was $23 million in 2020, and $21 million in both 2019 and 2018. At December 31, 2020, 57,396 shares of restricted stock and 812,947 RSUs were expected to vest with an aggregate intrinsic value of $2 million and $35 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Income tax expense is summarized as follows: (In millions) 2020 2019 2018 Federal: Current $ 153 $ 195 $ 210 Deferred (47) (1) (1) Total Federal 106 194 209 State: Current 38 44 49 Deferred (11) (1) 1 Total State 27 43 50 Total $ 133 $ 237 $ 259 Income tax expense computed at the statutory federal income tax rate of 21% reconciles to actual income tax expense as follows: (In millions) 2020 2019 2018 Income tax expense at statutory federal rate $ 141 $ 221 $ 240 State income taxes including credits, net 21 34 40 Other nondeductible expenses 8 13 15 Nontaxable income (32) (28) (24) Share-based compensation (1) (4) (7) Tax credits and other taxes (4) 1 (5) Total $ 133 $ 237 $ 259 The tax effects of temporary differences that give rise to significant portions of the deferred tax assets (“DTA”) and deferred tax liabilities (“DTL”) are presented below: (In millions) December 31, 2020 2019 Gross deferred tax assets: Book loan loss deduction in excess of tax $ 205 $ 137 Pension and postretirement 1 5 Deferred compensation 71 72 Lease liabilities 59 61 Other 24 35 Total deferred tax assets before valuation allowance 360 310 Valuation allowance — — Total deferred tax assets 360 310 Gross deferred tax liabilities: Premises and equipment, due to differences in depreciation (81) (66) Federal Home Loan Bank stock dividends (2) (2) Leasing operations (55) (52) Prepaid expenses (6) (6) Prepaid pension reserves (6) (12) Mortgage servicing (8) (7) Security investments and derivative fair value adjustments (102) (17) Deferred loan fees (32) (30) ROU assets (53) (55) Equity investments (18) (26) Total deferred tax liabilities (363) (273) Net deferred tax assets (liabilities) $ (3) $ 37 The amount of the net DTL is included with other liabilities, and the amount of the net DTA is included with other assets in the balance sheet. There is no valuation allowance at December 31, 2020 or December 31, 2019. At December 31, 2020, the tax effect of remaining net operating loss and tax credit carryforward was less than $1 million, expiring through 2030. We evaluate DTAs on a regular basis to determine whether a valuation allowance is required. In conducting this evaluation, we have considered all available evidence, both positive and negative, based on the more likely than not criteria that such assets will be realized. This evaluation includes, but is not limited to: (1) available carryback potential to prior tax years; (2) potential future reversals of existing deferred tax liabilities, which historically have a reversal pattern generally consistent with DTAs; (3) potential tax planning strategies; and (4) future projected taxable income. Based on this evaluation, and considering the weight of the positive evidence compared to the negative evidence, we have concluded that a valuation allowance is not required as of December 31, 2020. We have a liability for unrecognized tax benefits relating to uncertain tax positions for tax credits on technology initiatives. A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: (In millions) 2020 2019 2018 Balance at beginning of year $ 14 $ 8 $ 6 Tax positions related to current year: Additions 2 2 1 Reductions — — — Tax positions related to prior years: Additions — 4 1 Reductions (5) — — Settlements with taxing authorities — — — Lapses in statutes of limitations — — — Balance at end of year $ 11 $ 14 $ 8 At both December 31, 2020 and 2019, the liability for unrecognized tax benefits included approximately $10 million (net of the federal tax benefit on state issues) that, if recognized, would affect the effective tax rate. The amount of gross unrecognized tax benefits related to tax credits on technology initiatives that may increase or decrease during the 12 months subsequent to December 31, 2020, is dependent on the timing and outcome of various federal and state examinations that are ongoing. Interest and penalties related to unrecognized tax benefits are included in income tax expense in the statement of income. At both December 31, 2020 and 2019, accrued interest and penalties recognized in the balance sheet, net of any federal and state tax benefits, were $1 million. We file income tax returns in U.S. federal and various state jurisdictions. We are no longer subject to income tax examinations for years prior to 2013 for federal and for certain state returns.

Net Earnings Per Common Share

Net Earnings Per Common Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
NET EARNINGS PER COMMON SHARE	NET EARNINGS PER COMMON SHARE Basic and diluted net earnings per common share based on the weighted average outstanding shares are summarized as follows: (In millions, except shares and per share amounts) 2020 2019 2018 Basic: Net income $ 539 $ 816 $ 884 Less common and preferred dividends 259 260 236 Undistributed earnings 280 556 648 Less undistributed earnings applicable to nonvested shares 2 4 5 Undistributed earnings applicable to common shares 278 552 643 Distributed earnings applicable to common shares 223 224 200 Total earnings applicable to common shares $ 501 $ 776 $ 843 Weighted average common shares outstanding (in thousands) 163,737 175,984 193,589 Net earnings per common share $ 3.06 $ 4.41 $ 4.36 Diluted: Total earnings applicable to common shares $ 501 $ 776 $ 843 Weighted average common shares outstanding (in thousands) 163,737 175,984 193,589 Dilutive effect of common stock warrants (in thousands) 1,641 9,926 11,959 Dilutive effect of stock options (in thousands) 235 594 953 Weighted average diluted common shares outstanding (in thousands) 165,613 186,504 206,501 Net earnings per common share $ 3.02 $ 4.16 $ 4.08 The following schedule presents the weighted average stock awards that were anti-dilutive and not included in the calculation of diluted earnings per share. (In thousands) 2020 2019 2018 Restricted stock and restricted stock units $ 1,338 $ 1,390 $ 1,602 Stock options 889 460 151

Operating Segment Information

Operating Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
OPERATING SEGMENT INFORMATION	OPERATING SEGMENT INFORMATION We manage our operations and prepare management reports and other information with a primary focus on geographic area. Our banking operations are managed under their own individual brand names, including Zions Bank, Amegy Bank, California Bank & Trust, National Bank of Arizona, Nevada State Bank, Vectra Bank Colorado, and The Commerce Bank of Washington. Performance assessment and resource allocation are based upon this geographic structure. The operating segment identified as “ Other” includes certain nonbank financial service subsidiaries, centralized back-office functions, and eliminations of transactions between segments. We allocate the cost of centrally provided services to the business segments based upon estimated or actual usage of those services. We also allocate capital based on the risk-weighted assets held at each business segment. We use an internal FTP allocation process to report results of operations for business segments. This process is continually refined. In the third quarter of 2019, we made changes to the FTP process to more accurately reflect the cost of funds for loans. Additionally, in the third quarter of 2020, we allocated the net interest income associated with our Treasury department to the affiliates. Historically, this amount was presented in the “Other” segment. Prior period amounts have been revised to reflect the impact of these changes had they been instituted for the periods presented. Total average loans and deposits presented for the banking segments include insignificant intercompany amounts between banking segments and may also include deposits with the “Other” segment. As of December 31, 2020, our banking business is conducted through seven locally managed and branded segments in distinct geographic areas. Zions Bank operates 95 branches in Utah, 25 branches in Idaho, and one branch in Wyoming. CB&T operates 85 branches in California. Amegy operates 76 branches in Texas. NBAZ operates 56 branches in Arizona. NSB operates 46 branches in Nevada. Vectra operates 34 branches in Colorado and one branch in New Mexico. TCBW operates two branches in Washington and one branch in Oregon. The accounting policies of the individual operating segments are the same as those of the Bank. Transactions between operating segments are primarily conducted at fair value, resulting in profits that are eliminated for reporting consolidated results of operations. The following schedule does not present total assets or income tax expense for each operating segment, but instead presents average loans, average deposits and income before income taxes because these are the metrics that management uses when evaluating performance and making decisions pertaining to the operating segments. The condensed statement of income identifies the components of income and expense which affect the operating amounts presented in the “Other” segment. The following schedule presents selected operating segment information: (In millions) Zions Bank Amegy CB&T 2020 2019 2018 2020 2019 2018 2020 2019 2018 SELECTED INCOME STATEMENT DATA Net interest income $ 650 $ 688 $ 662 $ 485 $ 489 $ 485 $ 512 $ 512 $ 508 Provision for credit losses 67 18 8 111 9 (80) 120 7 15 Net interest income after provision for credit losses 583 670 654 374 480 565 392 505 493 Noninterest income 158 147 147 133 138 126 95 88 82 Noninterest expense 446 471 460 329 344 344 305 316 308 Income before income taxes $ 295 $ 346 $ 341 $ 178 $ 274 $ 347 $ 182 $ 277 $ 267 SELECTED AVERAGE BALANCE SHEET DATA Total average loans $ 13,845 $ 13,109 $ 12,643 $ 13,114 $ 12,235 $ 11,358 $ 12,366 $ 10,763 $ 10,033 Total average deposits 18,370 15,561 15,149 12,970 11,627 11,160 13,763 11,522 11,268 (In millions) NBAZ NSB Vectra 2020 2019 2018 2020 2019 2018 2020 2019 2018 SELECTED INCOME STATEMENT DATA Net interest income $ 216 $ 223 $ 216 $ 146 $ 148 $ 142 $ 135 $ 135 $ 130 Provision for credit losses 35 2 8 37 (1) 1 34 3 6 Net interest income after provision for credit losses 181 221 208 109 149 141 101 132 124 Noninterest income 41 42 39 43 43 41 32 26 24 Noninterest expense 147 156 152 141 145 143 109 108 105 Income before income taxes $ 75 $ 107 $ 95 $ 11 $ 47 $ 39 $ 24 $ 50 $ 43 SELECTED AVERAGE BALANCE SHEET DATA Total average loans $ 5,099 $ 4,774 $ 4,608 $ 3,102 $ 2,630 $ 2,394 $ 3,401 $ 3,109 $ 2,924 Total average deposits 5,771 5,002 4,931 5,427 4,512 4,286 3,637 2,853 2,761 (In millions) TCBW Other Consolidated Bank 2020 2019 2018 2020 2019 2018 2020 2019 2018 SELECTED INCOME STATEMENT DATA Net interest income $ 52 $ 53 $ 52 $ 20 $ 24 $ 35 $ 2,216 $ 2,272 $ 2,230 Provision for credit losses 7 (1) 2 3 2 — 414 39 (40) Net interest income after provision for credit losses 45 54 50 17 22 35 1,802 2,233 2,270 Noninterest income 5 5 5 67 73 88 574 562 552 Noninterest expense 22 22 22 205 180 145 1,704 1,742 1,679 Income (loss) before income taxes $ 28 $ 37 $ 33 $ (121) $ (85) $ (22) $ 672 $ 1,053 $ 1,143 SELECTED AVERAGE BALANCE SHEET DATA Total average loans $ 1,460 $ 1,194 $ 1,118 $ 629 $ 451 $ 347 $ 53,016 $ 48,265 $ 45,425 Total average deposits 1,256 1,094 1,092 2,495 2,910 2,536 63,689 55,081 53,183

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	QUARTERLY FINANCIAL INFORMATION (UNAUDITED) Financial information by quarter for 2020 and 2019 is shown below. Certain prior period amounts have been reclassified to conform with the current year presentation. These reclassifications did not affect net income. See related discussion in Note 1. (In millions, except per share amounts) Fourth Quarter Third Quarter Second Quarter First Quarter 2020 Gross interest income $ 571 $ 581 $ 595 $ 622 Net interest income 550 555 563 548 Provision for credit losses (67) 55 168 258 Noninterest income 166 157 117 134 Noninterest expense 424 442 430 408 Income before income taxes 359 215 82 16 Net income 284 175 66 14 Preferred stock dividends (9) (8) (9) (8) Net earnings applicable to common shareholders 275 167 57 6 Net earnings per common share: Basic 1.66 1.01 0.34 0.04 Diluted 1.66 1.01 0.34 0.04 2019 Gross interest income $ 647 $ 677 $ 684 $ 675 Net interest income 559 567 569 576 Provision for credit losses 4 10 21 4 Noninterest income 152 146 132 132 Noninterest expense 472 415 424 430 Income before income taxes 235 288 256 274 Net income 183 222 198 213 Preferred stock dividends (9) (8) (9) (8) Net earnings applicable to common shareholders 174 214 189 205 Net earnings per common share: Basic 1.03 1.23 1.05 1.10 Diluted 0.97 1.17 0.99 1.04

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Business	Business Zions Bancorporation, National Association and its subsidiaries (collectively “Zions Bancorporation, N.A.,” “the Bank,” “we,” “our,” “us”) together comprise a bank headquartered in Salt Lake City, Utah. We provide a wide range of banking products and related services in 11 Western and Southwestern states through seven separately managed affiliates, as follows: Zions Bank in Utah, Idaho and Wyoming; California Bank & Trust (“CB&T”); Amegy Bank (“Amegy”) in Texas; National Bank of Arizona (“NBAZ”); Nevada State Bank (“NSB”); Vectra Bank Colorado (“Vectra”) in Colorado and New Mexico; and The Commerce Bank of Washington (“TCBW”) which operates under that name in Washington and under The Commerce Bank of Oregon (“TCBO”) in Oregon.
Basis of Financial Statement Presentation and Principles of Consolidation	Basis of Financial Statement Presentation and Principles of Consolidation The consolidated financial statements include our accounts and those of our majority-owned, consolidated subsidiaries. Unconsolidated investments where we have the ability to exercise significant influence over the operating and financial policies of the respective investee are accounted for using the equity method of accounting. All significant intercompany accounts and transactions have been eliminated in consolidation. Assets held in an agency or fiduciary capacity are not included in the Consolidated Financial Statements. The consolidated financial statements have been prepared in accordance with United States (“U.S.”) generally accepted accounting principles (“GAAP”) and prevailing practices within the financial services industry. References to GAAP, including standards promulgated by the Financial Accounting Standards Board (“FASB”), are made according to sections of the Accounting Standards Codification (“ASC”). Changes to the ASC are made with Accounting Standards Updates (“ASU”) that include consensus issues of the Emerging Issues Task Force. In certain cases, ASUs are issued jointly with International Financial Reporting Standards.
Reclassification Policy	Certain prior year amounts have been reclassified to conform with the current year presentation. These reclassifications did not affect net income or shareholders’ equity.
Variable Interest Entities	Variable Interest Entities A variable interest entity (“VIE”) is consolidated when a company is the primary beneficiary of the VIE. Current accounting guidance requires continuous analysis on a qualitative rather than a quantitative basis to determine the primary beneficiary of a VIE. At the commencement of our involvement, and periodically thereafter, we consider our consolidation conclusions for all entities with which we are involved. As of December 31, 2020, and 2019, we have no VIEs that have been consolidated in our financial statements.
Statement of Cash Flows	Statement of Cash Flows For purposes of presentation in the consolidated statements of cash flows, “cash and cash equivalents” are defined as those amounts included in cash and due from banks in the consolidated balance sheets.
Fair Value Estimates	Fair Value Estimates We measure many of our assets and liabilities on a fair value basis. Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. To improve consistency and comparability in fair value measurements, GAAP has established a hierarchy to prioritize the valuation inputs among three levels. We prioritize quoted prices in active markets and minimize reliance on unobservable inputs when possible. When observable market prices are not available, fair value is estimated using modeling techniques such as discounted cash flow analysis. These modeling techniques use assumptions that market Fair Value Measurement Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. To measure fair value, a hierarchy has been established that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. This hierarchy uses the following three levels of inputs to measure the fair value of assets and liabilities: Level 1 — Quoted prices in active markets for identical assets or liabilities in active markets that we have the ability to access; Level 2 — Observable inputs other than Level 1, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in less active markets, observable inputs other than quoted prices that are used in the valuation of an asset or liability, and inputs that are derived principally from or corroborated by observable market data by correlation or other means; and Level 3 — Unobservable inputs supported by little or no market activity for financial instruments whose value is determined by pricing models, discounted cash flow methodologies or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. The level in the fair value hierarchy within which the fair value measurement is classified is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Market activity is presumed to be orderly in the absence of evidence of forced or disorderly sales, although such sales may still be indicative of fair value. Applicable accounting guidance precludes the use of blockage factors or liquidity adjustments due to the quantity of securities held by an entity. We use fair value to measure certain assets and liabilities on a recurring basis when fair value is the primary measure for accounting. Fair value is used on a nonrecurring basis to measure certain assets when adjusting carrying values, such as the application of lower of cost or fair value accounting, including recognition of impairment on assets. Fair value is also used when providing required disclosures for certain financial instruments. Fair Value Policies and Procedures We have various policies, processes, and controls in place to ensure that fair values are reasonably developed, reviewed, and approved for use. These include a Securities Valuation Committee, comprised of executive management, that reviews and approves on a quarterly basis the key components of fair value estimation, including critical valuation assumptions for Level 3 modeling. A Model Risk Management Group conducts model validations, including internal models, and sets policies and procedures for revalidation, including the timing of revalidation. Third-party Service Providers We use a third party pricing service to measure fair value for approximately 95% of our AFS Level 2 securities. Fair value measurements for other AFS Level 2 securities generally use certain inputs corroborated by market data and include standard discounted cash flow analysis. For Level 2 securities, the third-party pricing service provides documentation on an ongoing basis that presents market corroborative data, including detailed pricing information and market reference data. The documentation includes benchmark yields, reported trades, broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data, including information from the vendor trading platform. We review, test, and validate this information as appropriate. Absent observable trade data, we do not adjust prices from our third-party sources. The following describes the hierarchy designations, valuation methodologies and key inputs to measure fair value on a recurring basis for designated financial instruments: Available-for-Sale U.S. Treasury, Agencies and Corporations U.S. Treasury securities are measured under Level 1 using quoted market prices when available. U.S. agencies and corporations are measured under Level 2 generally using the previously mentioned third-party pricing service. Municipal Securities Municipal securities are measured under Level 2 using the third-party pricing service. Money Market Mutual Funds and Other Money market mutual funds and other securities are measured under Level 1 or Level 2. For Level 1, quoted market prices are used which may include net asset values (“NAVs”) or their equivalents. Level 2 valuations generally use quoted prices for similar securities. Trading Account Securities in the trading account are generally measured under Level 2 using third-party pricing service providers as described previously. Held-to-Maturity HTM securities are carried at amortized cost, but for disclosure purposes are measured at fair value using a third-party pricing service or an internal model. The internal model utilizes observable market yields as inputs. Bank-owned Life Insurance BOLI is measured under Level 2 according to CSVs of the insurance policies that are provided by a third-party service. Nearly all policies are general account policies with CSVs based on our claims on the assets of the insurance companies. The insurance companies’ investments include predominantly fixed-income securities consisting of investment-grade corporate bonds and various types of mortgage instruments. Management regularly reviews its BOLI investment performance, including concentrations among insurance providers. Private Equity Investments PEIs are generally measured under Level 3. The majority of these PEIs are held in our Small Business Investment Company (“SBIC”) and are early-stage venture investments. The fair value measurements of these investments are reviewed at least on a quarterly basis, including whenever a new round of financing occurs. Certain of these investments may be measured using multiples of operating performance. The fair value measurements of PEIs are reviewed on a quarterly basis by the Securities Valuation Committee. The Equity Investments Committee, consisting of executives familiar with the investments, reviews periodic financial information, including audited financial statements when available. Certain valuation analytics may be employed that include current and projected financial performance, recent financing activities, economic and market conditions, market comparable companies, market liquidity, sales restrictions, and other factors. A significant change in the expected performance of the individual investment would result in a change in the fair value measurement of the investment. The amount of unfunded commitments to invest is disclosed in Note 16. Certain restrictions apply for the redemption of these investments and certain investments are prohibited by the Volcker Rule. See discussions in Notes 5 and 16. Agriculture Loan Servicing This asset results from our servicing of agriculture loans approved and funded by Federal Agricultural Mortgage Corporation (“FAMC”). We provide this servicing under an agreement with FAMC for loans they own. The asset’s fair value represents our projection of the present value of future cash flows measured under Level 3 using discounted cash flow methodologies. Interest-only Strips Interest-only strips are created as a by-product of the securitization process. When the guaranteed portions of Small Business Administration (“SBA”) 7(a) loans are pooled, interest-only strips may be created in the pooling process. The asset’s fair value represents our projection of the present value of future cash flows measured under Level 3 using discounted cash flow methodologies. Deferred Compensation Plan Assets and Obligations Invested assets in the deferred compensation plan consist of shares of registered investment companies. These mutual funds are valued under Level 1 at quoted market prices, which represents the NAV of shares held by the plan at the end of the period. Derivatives Derivatives are measured according to their classification as either exchange-traded or over-the-counter. Exchange-traded derivatives consist of foreign currency exchange contracts measured under Level 1 because they are traded in active markets. Over-the-counter derivatives, including those for customers, consist of interest rate swaps and options. These derivatives are measured under Level 2 using third-party services. Observable market inputs include yield curves — the London Interbank Offered Rate (“LIBOR”) swap curve and relevant overnight index swap curves — foreign exchange rates, commodity prices, option volatilities, counterparty credit risk, and other related data. Credit valuation adjustments are required to reflect nonperformance risk for both us and the respective counterparty. These adjustments are determined generally by applying a credit spread to the total expected exposure of the derivative. Securities Sold, Not Yet Purchased Securities sold, not yet purchased, included in “Federal funds and other short-term borrowings” on the balance sheet, are measured under Level 1 using quoted market prices. If not available, quoted prices under Level 2 for similar securities are used. Loans Loans are generally measured at amortized cost, unless they do not share risk characteristics with other loans. For those loans, we estimate lifetime expected credit losses on an individual basis. When a loan is individually
Security Resell Agreements	Security Resell Agreements Security resell agreements represent overnight and term agreements with the majority maturing within 30 days. Due to increased cash reserves and in order to increase yield, we have extended the maturity of some security resell agreements beyond 30 days. As of December 31, 2020, 28% of all security resell agreements have a maturity beyond 30 days but none greater than 50 days. These agreements are generally treated as collateralized financing transactions and are carried at amounts at which the securities were acquired plus accrued interest. Either we, or in some instances third-parties on our behalf, take possession of the underlying securities. The fair value of such securities is monitored throughout the contract term to ensure that asset values remain sufficient to protect against counterparty default. We are permitted by contract to sell or repledge certain securities that we accept as collateral for security resell agreements. If sold, our obligation to return the collateral is recorded as “securities sold, not yet purchased” and included as a liability in “Federal funds and other short-term borrowings.” At December 31, 2020, we held $5.7 billion of securities for which we were permitted by contract to sell or repledge. Security resell agreements averaged $2.1 billion during 2020, and the maximum amount outstanding at any month-end during 2020 was $6.4 billion.
Investment Securities	Investment Securities We classify our investment securities according to their purpose and holding period. Gains or losses on the sale of securities are recognized using the specific identification method and recorded in noninterest income. Held-to-maturity (“HTM”) debt securities are carried at amortized cost with purchase discounts or premiums accreted or amortized into interest income over the contractual life of the security. We have the intent and ability to hold such securities until maturity. For HTM securities, the ACL is assessed consistent with the approach described in Note 6 for loans carried at amortized cost. Available-for-sale (“AFS”) securities are stated at fair value and generally consist of debt securities held for investment. Unrealized gains and losses of AFS securities, after applicable taxes, are recorded as a component of other comprehensive income (“OCI”). AFS securities in an unrealized loss position are formally reviewed on a quarterly basis for the presence of impairment. If we have an intent to sell an identified security, or it is more likely than not we will be required to sell the security before recovery of its amortized cost basis, then we recognize an impairment equal to any existing allowance written off against the security. If we do not have the intent to sell a security, and it is more likely than not that we will not be required to sell a security prior to recovery of its amortized cost basis, then we determine whether there is any impairment attributable to credit-related factors. The process, methodology, and factors considered to evaluate securities for impairment are described further in Note 5. Trading securities are stated at fair value and consist of securities acquired for short-term appreciation or other trading purposes. Realized and unrealized gains and losses are recorded in trading income, which is included in “Capital Markets and Foreign Exchange.” The fair values of investment securities, as estimated under current accounting guidance, are described in Note 3.
Leases	Leases As a lessee, when we enter a lease contract, we classify and account for the lease as either a finance lease or an operating lease, depending on the terms and conditions of the lease. A finance lease is recorded as an asset and a liability, and the asset is generally depreciated over the lease term. The lease liability is reduced as lease payments are made. An operating lease is recorded as a right-of-use (“ROU”) asset and operating lease liability. These balance sheet items are reduced as lease payments are made. Lease payments are expensed over the lease term; they are recorded as rent expense and are recognized on a straight-line basis. Lease-related assets are reviewed for impairment on an on-going basis. The lease term is the non-cancelable period that we have the right to use the leased asset. This term begins on the commencement date of the lease and incorporates options to extend or renew the lease when it is reasonably certain that we will exercise these options.
Loans and Allowance for Credit Losses	Loans Loans are reported at the principal amount outstanding, net of unearned income, unamortized purchase premiums and discounts, and net deferred loan fees and costs, which are amortized to interest income over the life of the loan using the interest method. Interest income is recognized on an accrual basis. At the time of origination, we determine whether loans will be held for investment or held for sale. We may subsequently change our intent to hold loans for investment and reclassify them as held for sale. Loans held for sale are carried at the lower of aggregate cost or fair value. A valuation allowance is recorded when cost exceeds fair value based on reviews at the time of reclassification and periodically thereafter. Gains and losses are recorded in noninterest income based on the difference between sales proceeds and carrying value. We evaluate loans throughout their lives for signs of credit deterioration, which may impact the loan’s status, and potentially impact our accounting for that loan. Loan status categories include past due as to contractual payments, nonaccrual, and restructured, including troubled debt restructurings (“TDRs”). Our accounting policies for these loan statuses and our estimation of the related allowance for loan and lease losses (“ALLL”) are described further in Note 6. In the ordinary course of business, we transfer portions of loans under participation agreements to manage credit risk and our portfolio concentration. We evaluate the loan participations to determine if they meet the appropriate accounting guidance to qualify as sales. Certain purchased loans require separate accounting procedures that are also described in Note 6. Allowance for Credit Losses The allowance for credit losses (“ACL”) includes the ALLL and the reserve for unfunded lending commitments (“RULC”). For periods prior to 2020, the ALLL represented management’s estimate of probable losses believed to be inherent in the loan portfolio at that time, and the RULC was estimated using the same procedures and methodologies as for the ALLL, in addition to assumptions regarding the probability and amount of unfunded commitments being drawn. On January 1, 2020, we adopted ASU 2016-13, Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, and its subsequent updates, often referred to as the Current Expected Credit Loss (“CECL”) model. CECL changes how the ACL is measured for loans and for additional financial assets, including HTM securities. Under CECL, the ACL will represent our estimate of current expected credit losses over the contractual term of the loan and lease portfolio and unfunded lending commitments as of the balance sheet date. The ACL for debt securities is estimated separately from loans. Further discussion of our estimation process for the ACL is included in Note 6.
Other Noninterest-bearing Investments	Other Noninterest-bearing Investments These investments include investments in private equity funds — referred to in this document as private equity investments (“PEIs”) — venture capital securities, securities acquired for various debt and regulatory requirements, bank-owned life insurance (“BOLI”), and certain other noninterest-bearing investments. See further discussion in Note 3. Certain PEIs and venture capital securities are accounted for under the equity method and some are reported at fair value. Changes in fair value and gains and losses from sales are recognized in noninterest income. The values assigned to the securities where no market quotations exist are based upon available information and may not necessarily represent amounts that will ultimately be realized. Such estimated amounts depend on future circumstances and will not be realized until the individual securities are liquidated. BOLI is accounted for at fair value based on the cash surrender values (“CSVs”) of the general account insurance policies. A third-party service provides these values. Other PEIs, and those acquired for various debt and regulatory requirements, are accounted for at cost less impairment (if any), plus or minus observable price changes from an identical or similar investment of the same issuer, with such changes recognized in income. Periodic reviews are conducted for impairment by comparing carrying values with estimates of fair value determined according to the previous discussion.
Premises, Equipment and Software, Net	Premises, Equipment and Software, Net Premises, equipment, and software are stated at cost, net of accumulated depreciation and amortization. Depreciation, computed primarily on the straight-line method, is charged to operations over the estimated useful lives of the properties, generally 25 to 40 years for buildings, three three to 10 years for software, including capitalized costs related to our technology initiatives. Leasehold improvements are amortized over the terms of the respective leases or the estimated useful lives of the improvements (including any extension options that are reasonably certain to be exercised), whichever is shorter. Premises, equipment and software are evaluated for impairment on a periodic basis.
Goodwill and Identifiable Intangible Assets	Goodwill and Identifiable Intangible AssetsGoodwill and intangible assets deemed to have indefinite lives are not amortized. We subject these assets to annual specified impairment tests as of the beginning of the fourth quarter and more frequently if changing conditions warrant.
Business Combinations	Business Combinations Business combinations are accounted for under the acquisition method of accounting. Upon initially obtaining control, we recognize 100% of all acquired assets and all assumed liabilities, regardless of the percentage owned. The assets and liabilities are recorded at their estimated fair values, with goodwill being recorded when such fair values are less than the cost of acquisition. Certain transaction and restructuring costs are expensed as incurred. Changes to estimated fair values from a business combination are recognized as an adjustment to goodwill over the measurement period, which cannot exceed one year from the acquisition date. Results of operations of the acquired business are included in our statement of income from the date of acquisition.
Other Real Estate Owned	Other Real Estate Owned Other real estate owned (“OREO”) consists principally of commercial and residential real estate obtained in partial or total satisfaction of loan obligations. Amounts are recorded initially at fair value (less any selling costs) based on property appraisals at the time of transfer and subsequently at the lower of cost or fair value (less any selling costs).
Derivative Instruments	Derivative Instruments We use derivative instruments — including interest rate swaps and purchased and sold options such as floors and basis swaps—as part of our overall interest rate risk management strategy. Derivatives are an important tool used in managing our overall asset and liability sensitivities to remain within management’s stated interest rate risk thresholds. Their use allows us to adjust and align our naturally occurring mix of fixed and floating-rate assets and liabilities to manage interest income volatility by synthetically converting variable-rate assets to fixed-rate, or synthetically converting fixed-rate funding instruments to floating-rates. We also execute both interest rate and short-term foreign currency derivative instruments with our commercial banking customers to facilitate their risk management strategies. These derivatives are immediately hedged by offsetting derivatives with third-parties such that we minimize our net risk exposure as a result of such transactions. We record all derivatives at fair value in the balance sheet as either other assets or other liabilities. The accounting for the change in value of a derivative depends on whether or not the transaction has been designated and qualifies
Derivatives in Designated Accounting Hedge	Derivatives in Designated Accounting Hedge We apply hedge accounting to certain derivatives executed for risk management purposes, primarily interest rate risk. To qualify for hedge accounting, a derivative must be highly effective at reducing the risk associated with the exposure being hedged and the hedging relationship must be formally documented. We primarily use regression analysis to assess the effectiveness of each hedging relationship, unless the hedge qualifies for other methods of assessing effectiveness (e.g., shortcut or critical terms match), both at inception and on an ongoing basis. We designate derivatives as fair value and cash flow hedges for accounting purposes and these hedges can be a significant aspect of our overall interest risk sensitivity management. We may add additional hedging strategies and apply hedge accounting to the strategies as it deems necessary. See Note 7 for more information regarding the accounting for derivatives designated as hedging instruments.
Commitments and Letters of Credit	Commitments and Letters of Credit In the ordinary course of business, we enter into commitments to extend credit, commercial letters of credit, and standby letters of credit. Such financial instruments are recorded in the financial statements when they become payable. The credit risk associated with these commitments is evaluated in a manner similar to the ALLL. The RULC is presented separately in the balance sheet.
Revenue Recognition	Revenue Recognition Service charges and fees on deposit accounts are recognized in accordance with published deposit account agreements for customer accounts or contractual agreements for commercial accounts. Other service charges, commissions, and fees include interchange fees, bank services, and other fees, which are generally recognized at the time of transaction or as the services are performed.
Share-based Compensation	Share-based Compensation Share-based compensation generally includes grants of stock options, restricted stock, restricted stock units (“RSUs”), and other awards to employees and nonemployee directors. We recognize compensation expense in the statement of income based on the grant-date value of the associated share-based awards. See further discussion in Note 19.
Income Taxes	Income Taxes Deferred tax assets (“DTAs”) and liabilities (“DTLs”) are determined based on temporary differences between financial statement asset and liability amounts and their respective tax basis and are measured using enacted tax laws and rates. The effect on DTAs and DTLs of a change in tax rates is recognized in income in the period that includes the enactment date. DTAs are recognized subject to management’s judgment that realization is more likely than not. Unrecognized tax benefits for uncertain tax positions relate primarily to tax credits on technology initiatives. See further discussion in Note 20.
Net Earnings Per Common Share	Net Earnings Per Common Share Net earnings per common share is based on net earnings applicable to common shareholders, which is net of preferred stock dividends. Basic net earnings per common share is based on the weighted average outstanding common shares during each year. Unvested share-based awards with rights to receive nonforfeitable dividends are considered participating securities and included in the computation of basic earnings per share. Diluted net earnings per common share is based on the weighted average outstanding common shares during each year, including common stock equivalents. Stock options, restricted stock, RSUs, and stock warrants are converted to common stock equivalents using the more dilutive of the treasury stock method or the two-class method. Diluted net earnings per common share excludes common stock equivalents whose effect is antidilutive. See further discussion in Note 21.
Recent Accounting Pronouncements	Accounting Standard Updates Description Date of adoption Effect on the financial statements or other significant matters Updates adopted during 2020 ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting As part of reference rate reform, the London Interbank Offered Rate (“LIBOR ” ) is expected to be discontinued by June 30, 2023 and is being replaced by observable or transaction-based alternative reference rates. This ASU addresses certain operational accounting concerns of modifying contracts such as debt, lease, and derivative agreements that reference LIBOR, or another rate, that is expected to be discontinued due to reference rate reform. The ASU provides temporary optional expedients and exceptions to the accounting requirements for contract modifications for contracts that reference LIBOR. This ASU also provides for a one-time election to sell or transfer to available-for-sale or trading certain qualifying held-to-maturity (“HTM ” ) debt securities. Additionally, this guidance provides various optional expedients for hedging relationships affected by reference rate reform. April 1, 2020 We adopted ASU 2020-04 on April 1, 2020; the impact upon adoption was not significant as no practical expedients were applied in the current period, but will be applied in future periods. ASU 2016-13, Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments and subsequent related ASUs This ASU, and subsequent updates, significantly changes how entities will measure credit losses for virtually all financial assets and certain other instruments that are not measured at fair value through net income that have the contractual right to receive cash. The update replaces the “incurred loss” approach with a current expected credit loss (“CECL ” ) model for instruments such as loans and HTM securities that are measured at amortized cost. The ASU requires credit losses relating to available-for sale (“AFS”) debt securities to be recorded through an allowance for credit loss (“ACL”) rather than a reduction of the carrying amount and replaces the historically required other-than-temporary impairment (“OTTI”) analysis. It also changes the accounting for purchased credit-impaired debt securities and loans. The ASU retains many of the current disclosure requirements in U.S. GAAP and expands other disclosure requirements. The new guidance is effective for calendar year-end public companies beginning January 1, 2020. January 1, 2020 We adopted ASU 2016-13 and its subsequent updates on January 1, 2020; the impact upon adoption was an after-tax increase to retained earnings of approximately $20 million. Accounting Standard Updates Description Date of adoption Effect on the financial statements or other significant matters Updates adopted during 2020 ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This ASU removes the requirements in step two of the current goodwill impairment model, eliminating the requirement to calculate and compare the implied fair value of the reporting entity with the carrying amount of that entity, including goodwill, to measure any impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount of goodwill over its implied fair value of goodwill (i.e., measure the charge based on step one of the current guidance). January 1, 2020 We adopted ASU 2017-04 on January 1, 2020; the impact upon adoption was not significant. The transition and adoption provisions were applied prospectively.
Fair Value Measurement	Fair Value Estimates We measure many of our assets and liabilities on a fair value basis. Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. To improve consistency and comparability in fair value measurements, GAAP has established a hierarchy to prioritize the valuation inputs among three levels. We prioritize quoted prices in active markets and minimize reliance on unobservable inputs when possible. When observable market prices are not available, fair value is estimated using modeling techniques such as discounted cash flow analysis. These modeling techniques use assumptions that market Fair Value Measurement Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. To measure fair value, a hierarchy has been established that requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs. This hierarchy uses the following three levels of inputs to measure the fair value of assets and liabilities: Level 1 — Quoted prices in active markets for identical assets or liabilities in active markets that we have the ability to access; Level 2 — Observable inputs other than Level 1, including quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in less active markets, observable inputs other than quoted prices that are used in the valuation of an asset or liability, and inputs that are derived principally from or corroborated by observable market data by correlation or other means; and Level 3 — Unobservable inputs supported by little or no market activity for financial instruments whose value is determined by pricing models, discounted cash flow methodologies or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation. The level in the fair value hierarchy within which the fair value measurement is classified is determined based on the lowest level input that is significant to the fair value measurement in its entirety. Market activity is presumed to be orderly in the absence of evidence of forced or disorderly sales, although such sales may still be indicative of fair value. Applicable accounting guidance precludes the use of blockage factors or liquidity adjustments due to the quantity of securities held by an entity. We use fair value to measure certain assets and liabilities on a recurring basis when fair value is the primary measure for accounting. Fair value is used on a nonrecurring basis to measure certain assets when adjusting carrying values, such as the application of lower of cost or fair value accounting, including recognition of impairment on assets. Fair value is also used when providing required disclosures for certain financial instruments. Fair Value Policies and Procedures We have various policies, processes, and controls in place to ensure that fair values are reasonably developed, reviewed, and approved for use. These include a Securities Valuation Committee, comprised of executive management, that reviews and approves on a quarterly basis the key components of fair value estimation, including critical valuation assumptions for Level 3 modeling. A Model Risk Management Group conducts model validations, including internal models, and sets policies and procedures for revalidation, including the timing of revalidation. Third-party Service Providers We use a third party pricing service to measure fair value for approximately 95% of our AFS Level 2 securities. Fair value measurements for other AFS Level 2 securities generally use certain inputs corroborated by market data and include standard discounted cash flow analysis. For Level 2 securities, the third-party pricing service provides documentation on an ongoing basis that presents market corroborative data, including detailed pricing information and market reference data. The documentation includes benchmark yields, reported trades, broker-dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data, including information from the vendor trading platform. We review, test, and validate this information as appropriate. Absent observable trade data, we do not adjust prices from our third-party sources. The following describes the hierarchy designations, valuation methodologies and key inputs to measure fair value on a recurring basis for designated financial instruments: Available-for-Sale U.S. Treasury, Agencies and Corporations U.S. Treasury securities are measured under Level 1 using quoted market prices when available. U.S. agencies and corporations are measured under Level 2 generally using the previously mentioned third-party pricing service. Municipal Securities Municipal securities are measured under Level 2 using the third-party pricing service. Money Market Mutual Funds and Other Money market mutual funds and other securities are measured under Level 1 or Level 2. For Level 1, quoted market prices are used which may include net asset values (“NAVs”) or their equivalents. Level 2 valuations generally use quoted prices for similar securities. Trading Account Securities in the trading account are generally measured under Level 2 using third-party pricing service providers as described previously. Held-to-Maturity HTM securities are carried at amortized cost, but for disclosure purposes are measured at fair value using a third-party pricing service or an internal model. The internal model utilizes observable market yields as inputs. Bank-owned Life Insurance BOLI is measured under Level 2 according to CSVs of the insurance policies that are provided by a third-party service. Nearly all policies are general account policies with CSVs based on our claims on the assets of the insurance companies. The insurance companies’ investments include predominantly fixed-income securities consisting of investment-grade corporate bonds and various types of mortgage instruments. Management regularly reviews its BOLI investment performance, including concentrations among insurance providers. Private Equity Investments PEIs are generally measured under Level 3. The majority of these PEIs are held in our Small Business Investment Company (“SBIC”) and are early-stage venture investments. The fair value measurements of these investments are reviewed at least on a quarterly basis, including whenever a new round of financing occurs. Certain of these investments may be measured using multiples of operating performance. The fair value measurements of PEIs are reviewed on a quarterly basis by the Securities Valuation Committee. The Equity Investments Committee, consisting of executives familiar with the investments, reviews periodic financial information, including audited financial statements when available. Certain valuation analytics may be employed that include current and projected financial performance, recent financing activities, economic and market conditions, market comparable companies, market liquidity, sales restrictions, and other factors. A significant change in the expected performance of the individual investment would result in a change in the fair value measurement of the investment. The amount of unfunded commitments to invest is disclosed in Note 16. Certain restrictions apply for the redemption of these investments and certain investments are prohibited by the Volcker Rule. See discussions in Notes 5 and 16. Agriculture Loan Servicing This asset results from our servicing of agriculture loans approved and funded by Federal Agricultural Mortgage Corporation (“FAMC”). We provide this servicing under an agreement with FAMC for loans they own. The asset’s fair value represents our projection of the present value of future cash flows measured under Level 3 using discounted cash flow methodologies. Interest-only Strips Interest-only strips are created as a by-product of the securitization process. When the guaranteed portions of Small Business Administration (“SBA”) 7(a) loans are pooled, interest-only strips may be created in the pooling process. The asset’s fair value represents our projection of the present value of future cash flows measured under Level 3 using discounted cash flow methodologies. Deferred Compensation Plan Assets and Obligations Invested assets in the deferred compensation plan consist of shares of registered investment companies. These mutual funds are valued under Level 1 at quoted market prices, which represents the NAV of shares held by the plan at the end of the period. Derivatives Derivatives are measured according to their classification as either exchange-traded or over-the-counter. Exchange-traded derivatives consist of foreign currency exchange contracts measured under Level 1 because they are traded in active markets. Over-the-counter derivatives, including those for customers, consist of interest rate swaps and options. These derivatives are measured under Level 2 using third-party services. Observable market inputs include yield curves — the London Interbank Offered Rate (“LIBOR”) swap curve and relevant overnight index swap curves — foreign exchange rates, commodity prices, option volatilities, counterparty credit risk, and other related data. Credit valuation adjustments are required to reflect nonperformance risk for both us and the respective counterparty. These adjustments are determined generally by applying a credit spread to the total expected exposure of the derivative. Securities Sold, Not Yet Purchased Securities sold, not yet purchased, included in “Federal funds and other short-term borrowings” on the balance sheet, are measured under Level 1 using quoted market prices. If not available, quoted prices under Level 2 for similar securities are used. Loans Loans are generally measured at amortized cost, unless they do not share risk characteristics with other loans. For those loans, we estimate lifetime expected credit losses on an individual basis. When a loan is individually
Investment Securities, Impairment	Ongoing Policy We review investment securities on a quarterly basis for the presence of impairment. For AFS securities, we assess whether impairment is present on an individual security basis when the fair value of a debt security is less than its amortized cost basis at the balance sheet date. When determining if the fair value of an investment is less than the amortized cost basis, we have elected to exclude accrued interest from the amortized cost basis of the investment. If we have an intent to sell an identified security, or it is more likely than not we will be required to sell the security before recovery of its amortized cost basis, then we recognize an impairment equal to any existing allowance written off against the security. If we do not have the intent to sell a security, and it is more likely than not that we will not be required to sell a security prior to recovery of its amortized cost basis, then we determine whether there is any impairment attributable to credit-related factors. We analyze certain factors, primarily internal and external credit ratings, to determine if the decline in fair value below the amortized cost basis has resulted from a credit loss or other factors. If a credit impairment is determined to exist, then we measure the amount of credit loss and recognize an allowance for the credit loss. In measuring the credit loss, we generally compare the present value of cash flows expected to be collected from the security to the amortized cost basis of the security. These cash flows are credit adjusted using, among other things, assumptions for default probability and loss severity. Certain other unobservable inputs, such as prepayment rate assumptions, are also utilized. In addition, certain internal models may be utilized. To determine the credit-related portion of impairment, we use the security-specific effective interest rate when estimating the present value of cash flows. If the present value of cash flows is less than the amortized cost basis of the security, then this amount is recorded as an allowance for credit loss, limited to the amount that the fair value is less than the amortized cost basis (i.e., the credit impairment cannot result in the security being carried at an amount lower than its fair value). The assumptions used to estimate the expected cash flows depends on the particular asset class, structure and credit rating of the security. Declines in fair value that are not recorded in the allowance are recorded in other comprehensive income, net of applicable taxes.

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Recent Accounting Pronouncements	Accounting Standard Updates Description Date of adoption Effect on the financial statements or other significant matters Updates adopted during 2020 ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting As part of reference rate reform, the London Interbank Offered Rate (“LIBOR ” ) is expected to be discontinued by June 30, 2023 and is being replaced by observable or transaction-based alternative reference rates. This ASU addresses certain operational accounting concerns of modifying contracts such as debt, lease, and derivative agreements that reference LIBOR, or another rate, that is expected to be discontinued due to reference rate reform. The ASU provides temporary optional expedients and exceptions to the accounting requirements for contract modifications for contracts that reference LIBOR. This ASU also provides for a one-time election to sell or transfer to available-for-sale or trading certain qualifying held-to-maturity (“HTM ” ) debt securities. Additionally, this guidance provides various optional expedients for hedging relationships affected by reference rate reform. April 1, 2020 We adopted ASU 2020-04 on April 1, 2020; the impact upon adoption was not significant as no practical expedients were applied in the current period, but will be applied in future periods. ASU 2016-13, Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments and subsequent related ASUs This ASU, and subsequent updates, significantly changes how entities will measure credit losses for virtually all financial assets and certain other instruments that are not measured at fair value through net income that have the contractual right to receive cash. The update replaces the “incurred loss” approach with a current expected credit loss (“CECL ” ) model for instruments such as loans and HTM securities that are measured at amortized cost. The ASU requires credit losses relating to available-for sale (“AFS”) debt securities to be recorded through an allowance for credit loss (“ACL”) rather than a reduction of the carrying amount and replaces the historically required other-than-temporary impairment (“OTTI”) analysis. It also changes the accounting for purchased credit-impaired debt securities and loans. The ASU retains many of the current disclosure requirements in U.S. GAAP and expands other disclosure requirements. The new guidance is effective for calendar year-end public companies beginning January 1, 2020. January 1, 2020 We adopted ASU 2016-13 and its subsequent updates on January 1, 2020; the impact upon adoption was an after-tax increase to retained earnings of approximately $20 million. Accounting Standard Updates Description Date of adoption Effect on the financial statements or other significant matters Updates adopted during 2020 ASU 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment This ASU removes the requirements in step two of the current goodwill impairment model, eliminating the requirement to calculate and compare the implied fair value of the reporting entity with the carrying amount of that entity, including goodwill, to measure any impairment charge. Instead, entities will record an impairment charge based on the excess of a reporting unit’s carrying amount of goodwill over its implied fair value of goodwill (i.e., measure the charge based on step one of the current guidance). January 1, 2020 We adopted ASU 2017-04 on January 1, 2020; the impact upon adoption was not significant. The transition and adoption provisions were applied prospectively.

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value by Class on a Recurring Basis	Assets and liabilities measured at fair value by class on a recurring basis are summarized as follows: (In millions) December 31, 2020 Level 1 Level 2 Level 3 Total ASSETS Investment securities: Available-for-sale: U.S. Treasury, agencies and corporations $ 192 $ 13,944 $ — $ 14,136 Municipal securities 1,420 1,420 Other debt securities 175 175 Total Available-for-sale 192 15,539 — 15,731 Trading account 111 155 266 Other noninterest-bearing investments: Bank-owned life insurance 532 532 Private equity investments 1 80 80 Other assets: Agriculture loan servicing and interest-only strips 16 16 Deferred compensation plan assets 120 120 Derivatives: Derivatives not designated as hedges: Interest rate 411 411 Foreign exchange 4 4 Total Assets $ 427 $ 16,637 $ 96 $ 17,160 LIABILITIES Securities sold, not yet purchased $ 61 $ — $ — $ 61 Other liabilities: Derivatives: Derivatives not designated as hedges: Interest rate 34 34 Foreign exchange 4 4 Total Liabilities $ 65 $ 34 $ — $ 99 1 The level 1 PEIs amount relates to the portion of our SBIC investments that are now publicly traded. (In millions) December 31, 2019 Level 1 Level 2 Level 3 Total ASSETS Investment securities: Available-for-sale: U.S. Treasury, agencies and corporations $ 25 $ 12,356 $ — $ 12,381 Municipal securities 1,319 1,319 Other debt securities 25 25 Total Available-for-sale 25 13,700 — 13,725 Trading account 65 117 182 Other noninterest-bearing investments: Bank-owned life insurance 525 525 Private equity investments 9 107 116 Other assets: Agriculture loan servicing and interest-only strips 18 18 Deferred compensation plan assets 113 113 Derivatives: Derivatives not designated as hedges: Interest rate 149 149 Foreign exchange 4 4 Total Assets $ 216 $ 14,491 $ 125 $ 14,832 LIABILITIES Securities sold, not yet purchased $ 66 $ — $ — $ 66 Other liabilities: Derivatives: Derivatives not designated as hedges: Interest rate 15 15 Foreign exchange 4 4 Total Liabilities $ 70 $ 15 $ — $ 85
Schedule of Assets and Liabilities Measured At Fair Value By Class on a Recurring Basis Using Level 3 Inputs	The following schedule reconciles the beginning and ending balances of assets and liabilities that are measured at fair value by financial instrument on a recurring basis using Level 3 inputs: Level 3 Instruments December 31, 2020 December 31, 2019 (In millions) Private Ag loan svcg and int-only strips Private Ag loan svcg and int-only strips Balance at beginning of year $ 107 $ 18 $ 102 $ 18 Securities gains (losses), net (5) — 2 — Other noninterest income (expense) — (1) — 1 Purchases 9 — 10 — Redemptions and paydowns — (1) — (1) Other (31) — (7) — Balance at end of year $ 80 $ 16 $ 107 $ 18 1 This represents the value of a private equity investment at the beginning of the quarter during which it became publicly traded.
Schedule of Realized Gain (Loss)	The reconciliation of Level 3 instruments includes the following realized gains and losses in the statement of income: (In millions) Year Ended 2020 2019 Securities gains (losses), net $ 18 $ (9)
Schedule of Assets With Fair Value Changes on Nonrecurring Basis	Included in the balance sheet amounts are the following amounts of assets that had fair value changes measured on a nonrecurring basis: (In millions) Fair value at December 31, 2020 Gains (losses) from Level 1 Level 2 Level 3 Total ASSETS Private equity investments, carried at cost $ — $ — $ 1 $ 1 $ (1) Collateral-dependent loans — 14 — 14 (14) Other real estate owned — 1 — 1 (2) Total $ — $ 15 $ 1 $ 16 $ (17) (In millions) Fair value at December 31, 2019 Gains (losses) from Level 1 Level 2 Level 3 Total ASSETS Private equity investments, carried at cost $ — $ — $ 1 $ 1 $ (1) Collateral-dependent loans — — — — — Other real estate owned — — — — (1) Total $ — $ — $ 1 $ 1 $ (2)
Schedule of Carrying Values and Estimated Fair Values of Financial Instruments	Following is a summary of the carrying values and estimated fair values of certain financial instruments: December 31, 2020 December 31, 2019 (In millions) Carrying Estimated Level Carrying Estimated Level Financial assets: Held-to-maturity investment securities $ 636 $ 640 2 $ 592 $ 597 2 Loans and leases (including loans held for sale), net of allowance 52,780 53,221 3 48,343 47,958 3 Financial liabilities: Time deposits 2,588 2,603 2 4,719 4,725 2 Long-term debt 1,336 1,346 2 1,723 1,751 2

Offsetting Assets and Liabili_2

Offsetting Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Offsetting [Abstract]
Schedule of Offsetting Assets and Liabilities	Gross and net information for selected financial instruments in the balance sheet is as follows: December 31, 2020 (In millions) Gross amounts not offset in the balance sheet Description Gross amounts recognized Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Cash collateral received/pledged Net amount Assets: Federal funds sold and security resell agreements $ 6,457 $ (692) $ 5,765 $ — $ — $ 5,765 Derivatives (included in other assets) 418 — 418 (6) (3) 409 Total assets $ 6,875 $ (692) $ 6,183 $ (6) $ (3) $ 6,174 Liabilities: Federal funds and other short-term borrowings $ 2,264 $ (692) $ 1,572 $ — $ — $ 1,572 Derivatives (included in other liabilities) 38 — 38 (6) (26) 6 Total liabilities $ 2,302 $ (692) $ 1,610 $ (6) $ (26) $ 1,578 December 31, 2019 (In millions) Gross amounts not offset in the balance sheet Description Gross amounts recognized Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Cash collateral received/pledged Net amount Assets: Federal funds sold and security resell agreements $ 694 $ (210) $ 484 $ — $ — $ 484 Derivatives (included in other assets) 153 — 153 (6) — 147 Total assets $ 847 $ (210) $ 637 $ (6) $ — $ 631 Liabilities: Federal funds and other short-term borrowings $ 2,263 $ (210) $ 2,053 $ — $ — $ 2,053 Derivatives (included in other liabilities) 19 — 19 (6) (10) 3 Total liabilities $ 2,282 $ (210) $ 2,072 $ (6) $ (10) $ 2,056
Schedule of Offsetting Assets and Liabilities	Gross and net information for selected financial instruments in the balance sheet is as follows: December 31, 2020 (In millions) Gross amounts not offset in the balance sheet Description Gross amounts recognized Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Cash collateral received/pledged Net amount Assets: Federal funds sold and security resell agreements $ 6,457 $ (692) $ 5,765 $ — $ — $ 5,765 Derivatives (included in other assets) 418 — 418 (6) (3) 409 Total assets $ 6,875 $ (692) $ 6,183 $ (6) $ (3) $ 6,174 Liabilities: Federal funds and other short-term borrowings $ 2,264 $ (692) $ 1,572 $ — $ — $ 1,572 Derivatives (included in other liabilities) 38 — 38 (6) (26) 6 Total liabilities $ 2,302 $ (692) $ 1,610 $ (6) $ (26) $ 1,578 December 31, 2019 (In millions) Gross amounts not offset in the balance sheet Description Gross amounts recognized Gross amounts offset in the balance sheet Net amounts presented in the balance sheet Financial instruments Cash collateral received/pledged Net amount Assets: Federal funds sold and security resell agreements $ 694 $ (210) $ 484 $ — $ — $ 484 Derivatives (included in other assets) 153 — 153 (6) — 147 Total assets $ 847 $ (210) $ 637 $ (6) $ — $ 631 Liabilities: Federal funds and other short-term borrowings $ 2,263 $ (210) $ 2,053 $ — $ — $ 2,053 Derivatives (included in other liabilities) 19 — 19 (6) (10) 3 Total liabilities $ 2,282 $ (210) $ 2,072 $ (6) $ (10) $ 2,056

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments [Abstract]
Summary of Investment Securities	December 31, 2020 (In millions) Amortized Gross Gross Estimated Held-to-maturity Municipal securities $ 636 $ 5 $ 1 $ 640 Available-for-sale U.S. Treasury securities 205 — 13 192 U.S. Government agencies and corporations: Agency securities 1,051 40 — 1,091 Agency guaranteed mortgage-backed securities 11,439 262 8 11,693 Small Business Administration loan-backed securities 1,195 — 35 1,160 Municipal securities 1,352 68 — 1,420 Other debt securities 175 — — 175 Total available-for-sale 15,417 370 56 15,731 Total investment securities $ 16,053 $ 375 $ 57 $ 16,371 December 31, 2019 (In millions) Amortized Gross Gross Estimated Held-to-maturity Municipal securities $ 592 $ 5 $ — $ 597 Available-for-sale U.S. Treasury securities 25 — — 25 U.S. Government agencies and corporations: Agency securities 1,301 5 4 1,302 Agency guaranteed mortgage-backed securities 9,518 83 42 9,559 Small Business Administration loan-backed securities 1,535 1 41 1,495 Municipal securities 1,282 37 — 1,319 Other debt securities 25 — — 25 Total available-for-sale 13,686 126 87 13,725 Total investment securities $ 14,278 $ 131 $ 87 $ 14,322
Contractual Maturities Debt Securities	December 31, 2020 Total debt investment securities Due in one year or less Due after one year through five years Due after five years through 10 years Due after 10 years (Dollar amounts in millions) Amortized cost Avg yield Amortized cost Avg yield Amortized cost Avg yield Amortized cost Avg yield Amortized cost Avg yield Held-to-maturity Municipal securities 1 $ 636 3.08 % $ 146 2.05 % $ 187 3.42 % $ 174 3.19 % $ 129 3.58 % Available-for-sale U.S. Treasury securities 205 0.99 50 0.09 — — — — 155 1.28 U.S. Government agencies and corporations: Agency securities 1,051 2.36 — — 292 1.73 238 2.65 521 2.58 Agency guaranteed mortgage-backed securities 11,439 1.87 — — 372 1.48 728 1.77 10,339 1.89 Small Business Administration loan-backed securities 1,195 1.56 — — 43 1.39 137 1.61 1,015 1.56 Municipal securities 1 1,352 2.44 99 1.83 640 2.39 432 2.60 181 2.59 Other debt securities 175 1.05 — — — — 160 0.87 15 2.93 Total available-for-sale securities 15,417 1.91 149 1.24 1,347 1.96 1,695 2.01 12,226 1.89 Total investment securities $ 16,053 1.95 % $ 295 1.64 % $ 1,534 2.14 % $ 1,869 2.12 % $ 12,355 1.91 % 1 The yields on tax-exempt securities are calculated on a tax-equivalent basis.
Summary of Amount of Gross Unrealized Losses for Debt Securities and Estimated Fair Value	The following schedule summarizes the amount of gross unrealized losses for debt securities and the estimated fair value by length of time the securities have been in an unrealized loss position: December 31, 2020 Less than 12 months 12 months or more Total (In millions) Gross Estimated Gross Estimated Gross Estimated Held-to-maturity Municipal securities $ 1 $ 96 $ — $ 12 $ 1 $ 108 Available-for-sale U.S. Treasury securities 13 142 — — 13 142 U.S. Government agencies and corporations: Agency securities — 6 — 2 — 8 Agency guaranteed mortgage-backed securities 7 1,197 1 179 8 1,376 Small Business Administration loan-backed securities — 15 35 1,068 35 1,083 Municipal securities — 19 — — — 19 Other — 150 — — — 150 Total available-for-sale 20 1,529 36 1,249 56 2,778 Total investment securities $ 21 $ 1,625 $ 36 $ 1,261 $ 57 $ 2,886 December 31, 2019 Less than 12 months 12 months or more Total (In millions) Gross Estimated Gross Estimated Gross Estimated Held-to-maturity Municipal securities $ — $ 73 $ — $ 45 $ — $ 118 Available-for-sale U.S. Government agencies and corporations: Agency securities 2 222 2 359 4 581 Agency guaranteed mortgage-backed securities 4 1,173 38 3,215 42 4,388 Small Business Administration loan-backed securities 1 172 40 1,215 41 1,387 Municipal securities — 50 — 5 — 55 Other — — — — — — Total available-for-sale 7 1,617 80 4,794 87 6,411 Total investment securities $ 7 $ 1,690 $ 80 $ 4,839 $ 87 $ 6,529
Debt Securities, Held-to-maturity	The amortized cost basis of HTM securities categorized by year of issuance is summarized as follows: December 31, 2020 Amortized cost basis by year of issuance (In millions) 2020 2019 2018 2017 2016 Prior Total Securities Held-to-maturity $ 216 $ 18 $ — $ 12 $ 176 $ 214 $ 636
Gains and Losses, Including OTTI, Recognized in Statement of Income	The following summarizes gains and losses that were recognized in the statement of income: 2020 2019 2018 (In millions) Gross Gross Gross Gross Gross Gross Other noninterest-bearing investments $ 27 $ 20 $ 20 $ 17 $ 17 $ 16 Net gains $ 7 $ 3 $ 1
Interest Income by Security Type	Interest income by security type is as follows: (In millions) 2020 2019 2018 Taxable Nontaxable Total Taxable Nontaxable Total Taxable Nontaxable Total Investment securities: Held-to-maturity $ 10 $ 10 $ 20 $ 9 $ 13 $ 22 $ 10 $ 14 $ 24 Available-for-sale 252 25 277 308 25 333 295 26 321 Trading — 7 7 1 6 7 1 4 5 Total $ 262 $ 42 $ 304 $ 318 $ 44 $ 362 $ 306 $ 44 $ 350

Loans, Leases, and Allowance _2

Loans, Leases, and Allowance For Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2020
Receivables [Abstract]
Summary of Major Portfolio Segment and Specific Loan Class	Loans and leases are summarized as follows according to major portfolio segment and specific class: December 31, (In millions) 2020 2019 Loans held for sale $ 81 $ 129 Commercial: Commercial and industrial $ 13,444 $ 14,760 PPP 5,572 — Leasing 320 334 Owner-occupied 8,185 7,901 Municipal 2,951 2,393 Total commercial 30,472 25,388 Commercial real estate: Construction and land development 2,345 2,211 Term 9,759 9,344 Total commercial real estate 12,104 11,555 Consumer: Home equity credit line 2,745 2,917 1-4 family residential 6,969 7,568 Construction and other consumer real estate 630 624 Bankcard and other revolving plans 432 502 Other 124 155 Total consumer 10,900 11,766 Total loans and leases $ 53,476 $ 48,709
Summary of Changes in the Allowance for Credit Losses	Changes in the ACL are summarized as follows: December 31, 2020 (In millions) Commercial Commercial Consumer Total Allowance for loan losses Balance at December 31, 2019 $ 341 $ 101 $ 53 $ 495 Adjustment for change in accounting standard (59) (32) 93 2 Balance at beginning of year (January 1, 2020) 282 69 146 497 Provision for loan losses 281 103 1 385 Gross loan and lease charge-offs 113 1 14 128 Recoveries 14 — 9 23 Net loan and lease charge-offs (recoveries) 99 1 5 105 Balance at end of year $ 464 $ 171 $ 142 $ 777 Reserve for unfunded lending commitments Balance at December 31, 2019 $ 39 $ 20 $ — $ 59 Adjustment for change in accounting standard (28) (8) 6 (30) Balance at beginning of year (January 1, 2020) 11 12 6 29 Provision for unfunded lending commitments 19 8 2 29 Balance at end of year $ 30 $ 20 $ 8 $ 58 Total allowance for credit losses Allowance for loan losses $ 464 $ 171 $ 142 $ 777 Reserve for unfunded lending commitments 30 20 8 58 Total allowance for credit losses $ 494 $ 191 $ 150 $ 835 December 31, 2019 (In millions) Commercial Commercial Consumer Total Allowance for loan losses Balance at beginning of year $ 331 $ 110 $ 54 $ 495 Provision for loan losses 42 (11) 6 37 Gross loan and lease charge-offs 57 4 17 78 Recoveries 25 6 10 41 Net loan and lease charge-offs (recoveries) 32 (2) 7 37 Balance at end of year $ 341 $ 101 $ 53 $ 495 Reserve for unfunded lending commitments Balance at beginning of year $ 40 $ 17 $ — $ 57 Provision for unfunded lending commitments (1) 3 — 2 Balance at end of year $ 39 $ 20 $ — $ 59 Total allowance for credit losses Allowance for loan losses $ 341 $ 101 $ 53 $ 495 Reserve for unfunded lending commitments 39 20 — 59 Total allowance for credit losses $ 380 $ 121 $ 53 $ 554
Summary of Nonaccrual Loans	The amortized cost basis of loans on nonaccrual status is summarized as follows: December 31, 2020 Amortized cost basis Total amortized cost basis (In millions) with no allowance with allowance Related allowance Commercial: Commercial and industrial $ 73 $ 67 $ 140 $ 22 Leasing — — — — Owner-occupied 38 38 76 — Municipal — — — 4 Total commercial 111 105 216 26 Commercial real estate: Construction and land development — — — — Term 12 19 31 3 Total commercial real estate 12 19 31 3 Consumer: Home equity credit line 2 14 16 3 1-4 family residential 14 89 103 9 Construction and other consumer real estate — — — — Bankcard and other revolving plans — 1 1 1 Other — — — — Total consumer loans 16 104 120 13 Total $ 139 $ 228 $ 367 $ 42 The amount of accrued interest receivables written off by reversing interest income during the period is summarized by loan portfolio segment as follows: (In millions) Year Ended December 31, 2020 Commercial $ 16 Commercial real estate 2 Consumer 1 Total $ 19
Summary of Past Due Loans (Accruing and Nonaccruing)	Past-due loans (accruing and nonaccruing) are summarized as follows: December 31, 2020 (In millions) Current 30-89 days 90+ days Total Total Accruing Nonaccrual loans that are current 1 Commercial: Commercial and industrial $ 13,388 $ 26 $ 30 $ 56 $ 13,444 $ 2 $ 109 PPP 5,572 — — — 5,572 — — Leasing 320 — — — 320 — 1 Owner-occupied 8,129 34 22 56 8,185 — 48 Municipal 2,951 — — — 2,951 — — Total commercial 30,360 60 52 112 30,472 2 158 Commercial real estate: Construction and land development 2,341 — 4 4 2,345 4 — Term 9,692 57 10 67 9,759 4 13 Total commercial real estate 12,033 57 14 71 12,104 8 13 Consumer: Home equity credit line 2,733 8 4 12 2,745 — 9 1-4 family residential 6,891 12 66 78 6,969 — 33 Construction and other consumer real estate 630 — — — 630 — Bankcard and other revolving plans 428 2 2 4 432 2 1 Other 123 1 — 1 124 — — Total consumer loans 10,805 23 72 95 10,900 2 43 Total $ 53,198 $ 140 $ 138 $ 278 $ 53,476 $ 12 $ 214 December 31, 2019 (In millions) Current 30-89 days 90+ days Total Total Accruing Nonaccrual loans that are current 1 Commercial: Commercial and industrial $ 14,665 $ 57 $ 38 $ 95 $ 14,760 $ 8 $ 54 Leasing 334 — — — 334 1 — Owner-occupied 7,862 20 19 39 7,901 — 44 Municipal 2,393 — — — 2,393 — — Total commercial 25,254 77 57 134 25,388 9 98 Commercial real estate: Construction and land development 2,206 5 — 5 2,211 — 1 Term 9,333 8 3 11 9,344 — 10 Total commercial real estate 11,539 13 3 16 11,555 — 11 Consumer: Home equity credit line 2,908 6 3 9 2,917 — 7 1-4 family residential 7,532 12 24 36 7,568 — 13 Construction and other consumer real estate 624 — — — 624 — — Bankcard and other revolving plans 499 2 1 3 502 1 — Other 154 1 — 1 155 — — Total consumer loans 11,717 21 28 49 11,766 1 20 Total $ 48,510 $ 111 $ 88 $ 199 $ 48,709 $ 10 $ 129 1 Represents nonaccrual loans that are not past due more than 30 days; however, full payment of principal and interest is still not expected.
Summary of Outstanding Loan Balances (Accruing and Nonaccruing) Categorized by Credit Quality Indicators	The amortized cost basis of loans and leases categorized by year of origination and by credit quality classifications as monitored by management are summarized as follows: December 31, 2020 Term Loans Revolving loans amortized cost basis Revolving loans converted to term loans amortized cost basis Amortized cost basis by year of origination (In millions) 2020 2019 2018 2017 2016 Prior Total Commercial: Commercial and industrial Pass $ 2,585 $ 2,743 $ 1,903 $ 829 $ 296 $ 228 $ 3,298 $ 109 $ 11,991 Special Mention 79 152 183 98 4 43 110 1 670 Accruing Substandard 123 157 129 44 26 17 141 6 643 Nonaccrual 57 2 10 8 2 15 36 10 140 Total commercial and industrial 2,844 3,054 2,225 979 328 303 3,585 126 13,444 PPP Pass 5,572 — — — — — — — 5,572 Total PPP 5,572 — — — — — — — 5,572 Leasing Pass 87 121 44 34 14 5 — — 305 Special Mention 1 — 2 1 — 6 — — 10 Accruing Substandard 2 1 1 1 — — — — 5 Nonaccrual — — — — — — — — — Total leasing 90 122 47 36 14 11 — — 320 Owner-occupied Pass 1,588 1,205 1,167 895 585 1,806 161 11 7,418 Special Mention 72 65 60 60 51 41 9 3 361 Accruing Substandard 28 64 61 37 35 98 6 1 330 Nonaccrual 8 11 15 11 6 23 2 — 76 Total owner-occupied 1,696 1,345 1,303 1,003 677 1,968 178 15 8,185 Municipal Pass 1,031 827 359 419 68 227 3 — 2,934 Special Mention — — — — — 8 — — 8 Accruing Substandard — — — — — 9 — — 9 Nonaccrual — — — — — — — — — Total municipal 1,031 827 359 419 68 244 3 — 2,951 Total commercial 11,233 5,348 3,934 2,437 1,087 2,526 3,766 141 30,472 Commercial real estate: Construction and land development Pass 558 933 267 41 1 6 423 3 2,232 Special Mention 24 43 11 — — — 5 — 83 Accruing Substandard — 30 — — — — — — 30 Nonaccrual — — — — — — — — — Total construction and land development 582 1,006 278 41 1 6 428 3 2,345 Term Pass 2,524 1,858 1,639 761 778 1,291 73 20 8,944 Special Mention 110 89 177 42 23 85 — 5 531 Accruing Substandard 41 34 96 30 18 34 — — 253 Nonaccrual 3 5 — 2 1 20 — — 31 Total term 2,678 1,986 1,912 835 820 1,430 73 25 9,759 Total commercial real estate 3,260 2,992 2,190 876 821 1,436 501 28 12,104 December 31, 2020 Term Loans Revolving loans amortized cost basis Revolving loans converted to term loans amortized cost basis Amortized cost basis by year of origination (In millions) 2020 2019 2018 2017 2016 Prior Total Consumer: Home equity credit line Pass — — — — — — 2,606 115 2,721 Special Mention — — — — — — 2 — 2 Accruing Substandard — — — — — — 6 — 6 Nonaccrual — — — — — — 11 5 16 Total home equity credit line — — — — — — 2,625 120 2,745 1-4 family residential Pass 1,185 1,017 833 1,081 1,174 1,570 — — 6,860 Special Mention — — — — — 2 — — 2 Accruing Substandard — — 1 — 2 1 — — 4 Nonaccrual 2 12 7 19 15 48 — — 103 Total 1-4 family residential 1,187 1,029 841 1,100 1,191 1,621 — — 6,969 Construction and other consumer real estate Pass 200 296 106 16 1 11 — — 630 Special Mention — — — — — — — — — Accruing Substandard — — — — — — — — — Nonaccrual — — — — — — — — — Total construction and other consumer real estate 200 296 106 16 1 11 — — 630 Bankcard and other revolving plans Pass — — — — — — 426 2 428 Special Mention — — — — — — — — — Accruing Substandard — — — — — — 3 — 3 Nonaccrual — — — — — — — 1 1 Total bankcard and other revolving plans — — — — — — 429 3 432 Other consumer Pass 51 35 22 10 4 2 — — 124 Special Mention — — — — — — — — — Accruing Substandard — — — — — — — — — Nonaccrual — — — — — — — — — Total other consumer 51 35 22 10 4 2 — — 124 Total consumer 1,438 1,360 969 1,126 1,196 1,634 3,054 123 10,900 Total loans $ 15,931 $ 9,700 $ 7,093 $ 4,439 $ 3,104 $ 5,596 $ 7,321 $ 292 $ 53,476
Summary of TDRs (Accruing and Nonaccruing) Categorized by Loan Class and Modification Type	Selected information on TDRs at year-end that includes the recorded investment on an accruing and nonaccruing basis by loan class and modification type is summarized in the following schedules: December 31, 2020 Recorded investment resulting from the following modification types: (In millions) Interest Maturity Principal Payment Other 1 Multiple modification types 2 Total Accruing Commercial: Commercial and industrial $ — $ — $ — $ — $ 3 $ 4 $ 7 Owner-occupied 5 1 — 4 4 8 22 Total commercial 5 1 — 4 7 12 29 Commercial real estate: Construction and land development — — — — — — — Term 1 — — 16 94 23 134 Total commercial real estate 1 — — 16 94 23 134 Consumer: Home equity credit line — 1 7 — — 2 10 1-4 family residential 4 1 3 — 2 15 25 Construction and other consumer real estate — — — — — — — Total consumer loans 4 2 10 — 2 17 35 Total accruing $ 10 $ 3 $ 10 $ 20 $ 103 $ 52 $ 198 Nonaccruing Commercial: Commercial and industrial $ — $ — $ — $ 3 $ 10 $ 52 $ 65 Owner-occupied 5 — — 3 — 10 18 Municipal — — — — — — — Total commercial 5 — — 6 10 62 83 Commercial real estate: Construction and land development — — — — — — — Term 2 — — 13 3 2 20 Total commercial real estate 2 — — 13 3 2 20 Consumer: Home equity credit line — — 2 — — — 2 1-4 family residential 1 1 — — — 6 8 Construction and other consumer real estate — — — — — — — Total consumer loans 1 1 2 — — 6 10 Total nonaccruing 8 1 2 19 13 70 113 Total $ 18 $ 4 $ 12 $ 39 $ 116 $ 122 $ 311 1 Includes TDRs that resulted from other modification types including, but not limited to, a legal judgment awarded on different terms, a bankruptcy plan confirmed on different terms, a settlement that includes the delivery of collateral in exchange for debt reduction, etc. 2 Includes TDRs that resulted from a combination of any of the previous modification types. December 31, 2019 Recorded investment resulting from the following modification types: (In millions) Interest Maturity Principal Payment Other 1 Multiple modification types 2 Total Accruing Commercial: Commercial and industrial $ 1 $ 2 $ — $ — $ 8 $ 5 $ 16 Owner-occupied 3 1 — — 4 7 15 Total commercial 4 3 — — 12 12 31 Commercial real estate: Construction and land development — — — — — — — Term 2 — — 1 — 3 6 Total commercial real estate 2 — — 1 — 3 6 Consumer: Home equity credit line — 2 7 — — 2 11 1-4 family residential 1 1 4 — 1 22 29 Construction and other consumer real estate — 1 — — — — 1 Total consumer loans 1 4 11 — 1 24 41 Total accruing $ 7 $ 7 $ 11 $ 1 $ 13 $ 39 $ 78 Nonaccruing Commercial: Commercial and industrial $ — $ 4 $ — $ 20 $ 4 $ 22 $ 50 Owner-occupied 5 — — — 1 4 10 Municipal — — — — — — — Total commercial 5 4 — 20 5 26 60 Commercial real estate: Construction and land development — — — — — — — Term 1 — — — 3 3 7 Total commercial real estate 1 — — — 3 3 7 Consumer: Home equity credit line — — 2 — — — 2 1-4 family residential — — 1 — 1 4 6 Construction and other consumer real estate — — — — — — — Total consumer loans — — 3 — 1 4 8 Total nonaccruing 6 4 3 20 9 33 75 Total $ 13 $ 11 $ 14 $ 21 $ 22 $ 72 $ 153 1 Includes TDRs that resulted from other modification types including, but not limited to, a legal judgment awarded on different terms, a bankruptcy plan confirmed on different terms, a settlement that includes the delivery of collateral in exchange for debt reduction, etc. 2 Includes TDRs that resulted from a combination of any of the previous modification types. The recorded investment of accruing and nonaccruing TDRs that had a payment default during the period listed below (and are still in default at year-end) and are within 12 months or less of being modified as TDRs is as follows: (In millions) December 31, 2020 December 31, 2019 Accruing Nonaccruing Total Accruing Nonaccruing Total Commercial: Commercial and industrial $ — $ 2 $ 2 $ — $ — $ — Owner-occupied — — — — 1 1 Total commercial — 2 2 — 1 1 Consumer: 1-4 family residential — 1 1 — — — Total consumer loans — 1 1 — — — Total $ — $ 3 $ 3 $ — $ 1 $ 1 Note: Total loans modified as TDRs during the 12 months previous to December 31, 2020, and 2019 were $228 million and $40 million, respectively.
Summary of Collateral-Dependent Loans	Selected information on loans for which the repayment is expected to be provided substantially through the operation or sale of the underlying collateral and the borrower is experiencing financial difficulties, including the type of collateral and the extent to which the collateral secures the loans, is summarized as follows: December 31, 2020 (In millions) Amortized Cost Major Types of Collateral Weighted Average LTV 1 Commercial: Commercial and industrial $ 20 Single family residential, Agriculture 55% Owner-occupied 10 Office Building 47% Commercial real estate: Term 12 Multi-family, Hotel/Motel, Retail 58% Consumer: Home equity credit line 3 Single family residential 34% 1-4 family residential 2 Single family residential 60% Total $ 47 1 The fair value is based on the most recent appraisal or other collateral evaluation.

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Derivative Instruments [Abstract]
Schedule of Derivative Amounts	Selected information with respect to notional amounts and recorded gross fair values at December 31, 2020, and 2019, and the related gain (loss) of derivative instruments for the years then ended is summarized as follows: December 31, 2020 December 31, 2019 Notional Fair value Notional Fair value (In millions) Other Other Other Other Derivatives designated as hedging instruments: Cash flow hedges of floating-rate assets: Purchased interest rate floors $ — $ — $ — $ — $ — $ — Receive-fixed interest rate swaps 3,150 — — 3,588 — — Fair value hedges: Debt hedges: Receive-fixed interest rate swaps 500 — — 1,500 — — Asset hedges: Pay-fixed interest rate swaps 383 3 — — — — Total derivatives designated as hedging instruments 4,033 3 — 5,088 — — Derivatives not designated as hedging instruments: Customer-facing interest rate derivatives 1, 2 5,986 390 2 4,409 146 5 Offsetting interest rate derivatives 2 5,986 3 409 4,422 5 157 Other interest rate derivatives 1,649 20 3 726 3 1 Foreign exchange derivatives 223 4 4 385 4 4 Total derivatives not designated as hedging instruments 13,844 417 418 9,942 158 167 Total derivatives $ 17,877 $ 420 $ 418 $ 15,030 $ 158 $ 167 1 Customer-facing interest rate derivative fair values include an $18 million and $11 million net credit valuation adjustment as of December 31, 2020, and December 31, 2019, respectively. These adjustments are required to reflect both our nonperformance risk and that of the respective counterparty. 2 The fair value amounts for these derivatives do not include the settlement amounts for those trades that are cleared. Once the settlement amounts with the clearing houses are included the derivative fair values would be the following: December 31, 2020 December 31, 2019 (In millions) Other assets Other liabilities Other assets Other liabilities Customer-facing interest rate derivatives $ 390 $ 2 $ 146 $ 5 Offsetting interest rate derivatives 1 29 — 9
Schedule of Derivative Gains (Losses) Deferred in OCI or Recognized in Earnings	The amount of derivative gains (losses) from cash flow and fair value hedges that was deferred in AOCI or recognized in earnings is summarized as follows: Year Ended December 31, 2020 (In millions) Effective portion of derivative gain/(loss) deferred in AOCI Excluded components deferred in AOCI (amortization approach) Amount of gain/(loss) reclassified from AOCI into income Interest on fair value hedges Hedge ineffectiveness / AOCI reclass due to missed forecast Cash flow hedges of floating-rate assets: 1 Purchased interest rate floors $ — $ — $ 11 $ — $ — Interest rate swaps 101 — 36 — — Fair value hedges of liabilities: Receive-fixed interest rate swaps — — — 6 — Basis amortization on terminated hedges 2, 3 — — — 13 — Fair value hedges of assets: Pay-fixed interest rate swaps — — — (1) — Basis amortization on terminated hedges 2, 3 — — — — — Total derivatives designated as hedging instruments $ 101 $ — $ 47 $ 18 $ — Year Ended December 31, 2019 (In millions) Effective portion of derivative gain/(loss) deferred in AOCI Excluded components deferred in AOCI (amortization approach) Amount of gain/(loss) reclassified from AOCI into income Interest on fair value hedges Hedge ineffectiveness / AOCI reclass due to missed forecast Cash flow hedges of floating-rate assets: 1 Purchased interest rate floors $ — $ 27 $ 3 $ — $ — Interest rate swaps 47 — (7) — — Fair value hedges of liabilities: Receive-fixed interest rate swaps — — — 3 — Basis amortization on terminated hedges 2, 3 — — — — — Fair value hedges of assets: Pay-fixed interest rate swaps — — — — — Basis amortization on terminated hedges 2, 3 — — — — — Total derivatives designated as hedging instruments $ 47 $ 27 $ (4) $ 3 $ — Note: These schedules are not intended to present at any given time our long/short position with respect to our derivative contracts. 1 Amounts recognized in OCI and reclassified from AOCI represent the effective portion of the derivative gain (loss). For the 12 months following December 31, 2020, we estimate that $61 million will be reclassified from AOCI into interest income. 2 Adjustment to interest expense resulting from the amortization of the debt basis adjustment on fixed-rate debt previously hedged by terminated receive-fixed interest rate. 3 The cumulative unamortized basis adjustment from previously terminated or redesignated fair value hedges as of December 31, 2020, is $12 million and $7 million of terminated fair value debt and asset hedges, respectively. The amortization of the cumulative unamortized basis adjustment from asset hedges is not shown in the schedules because it is not significant.
Schedule of Gains (Losses) Recognized From Derivatives Not Designated As Accounting Hedges	The amount of derivative gains (losses) recognized from derivatives not designated in accounting hedges is as follows: Noninterest (Other) Income/(Expense) (In millions) 2020 2019 Derivatives not designated as hedging instruments: Customer-facing interest rate derivatives $ 324 $ 146 Offsetting interest rate derivatives (300) (129) Other interest rate derivatives 8 — Foreign exchange derivatives 21 23 Total derivatives not designated as hedging instruments $ 53 $ 40
Schedule of Fair Value Hedges	The following schedule presents derivatives used in fair value hedge accounting relationships, as well as pre-tax gains/(losses) recorded on such derivatives and the related hedged items for the periods presented. Gain/(loss) recorded in income Twelve Months Ended Twelve Months Ended December 31, 2019 (In millions) Derivatives 2 Hedged items Total income statement impact Derivatives 2 Hedged items Total income statement impact Debt: Receive-fixed interest rate swaps 1,2 $ 63 $ (63) $ — $ 5 $ (5) $ — Assets: Pay-fixed interest rate swaps 1,2 28 (28) — — — — 1 Consists of hedges of benchmark interest rate risk of fixed-rate long-term debt and fixed-rate AFS securities. Gains and losses were recorded in net interest expense or income consistent with the hedged items. 2 The income/expense for derivatives does not reflect interest income/expense from periodic accruals and payments (which are reported above) to be consistent with the presentation of the gains/ (losses) on the hedged items.
Schedule of Hedged Item Included in Long-Term Debt	The following schedule provides selected information regarding the long-term debt in the statement of financial position in which the hedged item is included. Par value of hedged assets/(liabilities) Carrying amount of the hedged assets/(liabilities) Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets/(liabilities) (In millions) 2020 2019 2020 2019 2020 2019 Long-term fixed-rate debt 1,2 $ (500) $ (1,500) $ (537) $ (1,510) $ (37) $ (10) Fixed-rate AFS securities 1,2 383 — 362 — (21) — 1 Carrying amounts displayed above exclude issuance and purchase discounts or premiums and unamortized issuance/acquisition costs. 2 The carrying amount of the hedged items shown above (long-term fixed-rate debt and fixed-rate AFS securities) excludes amounts related to terminated fair value hedges.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Lease Related Assets and Liabilities	The following schedule presents lease-related assets and liabilities, their weighted average remaining life, and the weighted average discount rate. (Dollar amounts in millions) December 31, 2020 December 31, 2019 Operating assets and liabilities Operating right-of-use assets, net of amortization $ 213 $ 218 Operating lease liabilities 240 246 Weighted average remaining lease term (years) Operating leases 8.9 9.1 Finance leases 19.2 20.2 Weighted average discount rate Operating leases 2.9 % 3.2 % Finance leases 3.1 % 3.1 %
Lease Expense	The components of lease expense are as follows: Year Ended December 31, (In millions) 2020 2019 Operating lease costs $ 49 $ 48 Variable lease costs 49 53 Total lease cost $ 98 $ 101 Supplemental cash flow information related to leases is as follows: Year Ended December 31, (In millions) 2020 2019 Cash paid for amounts in the measurement of lease liabilities: Operating cash disbursements from operating leases $ 51 $ 50 ROU assets obtained in exchange for lease liabilities: Year Ended December 31, (In millions) 2020 2019 New operating lease liabilities $ 9 $ 10 New finance lease liabilities — 6 Total $ 9 $ 16
Lease Maturity Analysis	Maturities analysis for operating lease liabilities as of December 31, 2020 is as follows (contractual undiscounted lease payments): (In millions) Contractual lease payments 2021 $ 49 2022 46 2023 39 2024 30 2025 21 Thereafter 95 Total $ 280

Premises, Equipment and Softw_2

Premises, Equipment and Software, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Premises, Equipment and Software, Net	Premises, equipment and software, net are summarized as follows: (In millions) December 31, 2020 2019 Land $ 257 $ 235 Buildings 802 747 Furniture and equipment 420 442 Leasehold improvements 165 164 Software 581 507 Total 1 2,225 2,095 Less accumulated depreciation and amortization 1,016 953 Net book value $ 1,209 $ 1,142 1 Amounts include $213 million at December 31, 2020, and $105 million at December 31, 2019, of costs that have been capitalized but are not yet depreciating because the respective assets have not been placed in service.

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Related Accumulated Amortization	Core deposit and other intangible assets and related accumulated amortization are as follows at December 31: Gross carrying amount Accumulated amortization Net carrying amount (In millions) 2020 2019 2020 2019 2020 2019 Core deposit intangibles $ 167 $ 167 $ (167) $ (167) $ — $ — Customer relationships and other intangibles 30 28 (28) (28) 2 — Total $ 197 $ 195 $ (195) $ (195) $ 2 $ —
Schedule of Goodwill	Changes in the carrying amount of goodwill for operating segments with goodwill are as follows: (In millions) Zions Bank CB&T Amegy Consolidated Bank Balance at December 31, 2018 $ 20 $ 379 $ 615 $ 1,014 Impairment losses — — — — Balance at December 31, 2019 20 379 615 1,014 Impairment losses — — — — Balance at December 31, 2020 $ 20 $ 379 $ 615 $ 1,014

Deposits (Tables)

Deposits (Tables)	12 Months Ended
	Dec. 31, 2020
Deposits [Abstract]
Schedule of Maturities of All Time Deposits	At December 31, 2020, the scheduled maturities of all time deposits were as follows: (In millions) Amount 2021 $ 2,239 2022 189 2023 78 2024 42 2025 39 Thereafter 1 Total $ 2,588 The contractual maturities of time deposits with a denomination of $100,000 and over were as follows: (In millions) December 31, 2020 Three months or less $ 274 After three months through six months 204 After six months through twelve months 405 After twelve months 166 Total $ 1,049

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	12 Months Ended
	Dec. 31, 2020
Short-term Debt [Abstract]
Summary of Short-Term Borrowings	Selected information for FHLB advances and other short-term borrowings is as follows: (Dollar amounts in millions) 2020 2019 2018 Federal Home Loan Bank advances Average amount outstanding $ 206 $ 3,149 $ 2,971 Average rate 1.11 % 2.50 % 2.01 % Highest month-end balance $ 2,200 $ 4,950 $ 5,400 Year-end balance — 1,000 4,500 Average rate on outstanding advances at year-end — % 1.73 % 2.61 % Other short-term borrowings, year-end balances Federal funds purchased $ 1,105 $ 472 $ 541 Security repurchase agreements 406 515 527 Securities sold, not yet purchased 61 66 85 Federal funds purchased and other short-term borrowings $ 1,572 $ 2,053 $ 5,653

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Long-term Debt, Unclassified [Abstract]
Schedule of Long-Term Debt	Long-term debt is summarized as follows: December 31, (In millions) 2020 2019 Subordinated notes $ 619 $ 572 Senior notes 713 1,147 Finance lease obligations 4 4 Total $ 1,336 $ 1,723
Schedule of Subordinated Notes	Subordinated notes we issued consist of the following at December 31, 2020: (Dollar amounts in millions) Subordinated notes Coupon rate Balance Par amount Maturity 6.95% $ 87 $ 88 September 2028 3.25% 532 500 October 2029 Total $ 619 $ 588
Schedule of Senior Notes	Senior notes we issued consist of the following at December 31, 2020: (Dollar amounts in millions) Senior notes Coupon rate Balance Par amount Maturity 4.50% $ 132 $ 132 June 2023 3.50% 285 281 August 2021 3.35% 296 290 March 2022 Total $ 713 $ 703
Schedule of Maturities of Long-term Debt	Maturities of long-term debt are as follows for the years succeeding December 31, 2020: (In millions) 2021 $ 282 2022 289 2023 132 2024 — 2025 — Thereafter 585 Total $ 1,288

Shareholders' Equity (Tables)

Shareholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Summary of Preferred Stock	Preferred stock is summarized as follows: Shares at (Dollar amounts in millions) Carrying value at Authorized Outstanding Dividends payable Earliest Rate following earliest redemption date Dividends payable after rate change 2020 2019 (thousands) (thousands) Rate (when applicable) Series A $ 67 $ 67 140,000 66,139 > of 4.0% or 3mL+0.52% Qtrly Mar, Jun, Sep, Dec Dec 15, 2011 Series G 138 138 200,000 138,391 6.3% Qtrly Mar, Jun, Sep, Dec Mar 15, 2023 annual float-ing rate = 3mL+4.24% Series H 126 126 126,221 126,221 5.75% Qtrly Mar, Jun, Sep, Dec Jun 15, 2019 Series I 99 99 300,893 98,555 5.8% Semi-annually Jun, Dec Jun 15, 2023 annual float-ing rate = 3mL+3.8% Qtrly Mar, Jun, Sep, Dec Series J 136 136 195,152 136,368 7.2% Semi-annually Mar, Sep Sep 15, 2023 annual float-ing rate = 3mL+4.44% Qtrly Mar, Jun, Sep, Dec Total $ 566 $ 566
Schedule of Changes in Accumulated Other Comprehensive Income	Changes in AOCI by component are as follows: (In millions) Net unrealized gains (losses) on investment securities Net unrealized gains (losses) on derivatives and other Pension and post-retirement Total 2020 Balance at December 31, 2019 $ 29 $ 28 $ (14) $ 43 Other comprehensive income (loss) before reclassifications, net of tax 229 77 (9) 297 Amounts reclassified from AOCI, net of tax — (36) 21 (15) Other comprehensive income 229 41 12 282 Balance at December 31, 2020 $ 258 $ 69 $ (2) $ 325 Income tax expense included in other comprehensive income $ 74 $ 13 $ 4 $ 91 2019 Balance at December 31, 2018 $ (228) $ (1) $ (21) $ (250) Other comprehensive income before reclassifications, net of tax 257 24 6 287 Amounts reclassified from AOCI, net of tax — 5 1 6 Other comprehensive income 257 29 7 293 Balance at December 31, 2019 $ 29 $ 28 $ (14) $ 43 Income tax expense included in other comprehensive income $ 84 $ 10 $ 2 $ 96
Schedule of Reclassification out of Accumulated Other Comprehensive Income	Statement of Income (SI) (In millions) Amounts reclassified from AOCI 1 Details about AOCI components 2020 2019 2018 Affected line item Net unrealized gains (losses) on derivative instruments $ 47 $ (4) $ (4) SI Interest and fees on loans Income tax expense (benefit) 11 (1) (1) $ 36 $ (3) $ (3) Amortization of net actuarial loss $ (28) $ (2) $ (3) SI Other noninterest expense Income tax benefit (7) (1) (1) $ (21) $ (1) $ (2) 1 Positive reclassification amounts indicate increases to earnings in the statement of income.

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2020
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Summary of Actual Capital Amounts and Capital Ratios	Our capital amounts and ratios at December 31, 2020 and 2019 under Basel III are as follows: (Dollar amounts in millions) December 31, 2020 To be well-capitalized Amount Ratio Amount Ratio Basel III Regulatory Capital Amounts and Ratios Total capital (to risk-weighted assets) $ 7,862 14.1 % $ 5,587 10.0 % Tier 1 capital (to risk-weighted assets) 6,579 11.8 4,469 8.0 Common equity tier 1 capital (to risk-weighted assets) 6,013 10.8 3,631 6.5 Tier 1 capital (to average assets) 6,579 8.3 3,944 5.0 December 31, 2019 To be well-capitalized (Dollar amounts in millions) Amount Ratio Amount Ratio Basel III Regulatory Capital Amounts and Ratios Total capital (to risk-weighted assets) $ 7,411 13.2 % $ 5,604 10.0 % Tier 1 capital (to risk-weighted assets) 6,285 11.2 4,483 8.0 Common equity tier 1 capital (to risk-weighted assets) 5,719 10.2 3,643 6.5 Tier 1 capital (to average assets) 6,285 9.2 3,426 5.0 The schedule below presents our actual capital ratios in comparison to minimum capital ratios and capital ratios in excess of minimum capital requirements plus minimum capital conservation buffer requirements. December 31, 2020 Actual Capital Ratio Minimum Capital Ratio Capital Conservation Buffer Ratio Capital Ratio in Excess of Minimum Capital Ratio plus Capital Conservation Buffer Requirement Total capital (to risk-weighted assets) 14.1 % 8.0 % 2.5 % 3.6 % Tier 1 capital (to risk-weighted assets) 11.8 6.0 2.5 3.3 Common equity tier 1 capital (to risk-weighted assets) 10.8 4.5 2.5 3.8

Commitments, Guarantees, Cont_2

Commitments, Guarantees, Contingent Liabilities, and Related Parties (Tables)	12 Months Ended
	Dec. 31, 2020
Guarantees, Commitments And Contingencies [Abstract]
Schedule of Off-Balance Sheet Financial Instruments	Contractual amounts of the off-balance sheet financial instruments used to meet the financing needs of our customers are as follows: December 31, (In millions) 2020 2019 Net unfunded commitments to extend credit 1 $ 24,217 $ 23,099 Standby letters of credit: Financial 531 631 Performance 167 192 Commercial letters of credit 34 5 Total unfunded lending commitments $ 24,949 $ 23,927 1 Net of participations.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue Recognition and Deferred Revenue [Abstract]
Disaggregation of Revenue	The following schedule presents noninterest income and net revenue by operating segments: Zions Bank Amegy CB&T (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Commercial account fees $ 42 $ 41 $ 41 $ 37 $ 34 $ 34 $ 22 $ 23 $ 23 Card fees 49 51 50 24 28 29 14 16 15 Retail and business banking fees 21 23 24 15 17 16 11 13 14 Capital markets and foreign exchange fees (1) — — 5 6 6 — — — Wealth management and trust fees 23 17 16 16 12 10 8 4 4 Other customer-related fees 2 2 3 1 1 1 1 2 2 Total noninterest income from contracts with customers (ASC 606) 136 134 134 98 98 96 56 58 58 Other noninterest income (Non-ASC 606 customer related) 23 12 12 34 40 30 36 28 22 Total customer-related fees 159 146 146 132 138 126 92 86 80 Other noninterest income (noncustomer-related) (1) 1 1 1 — — 3 2 2 Total noninterest income 158 147 147 133 138 126 95 88 82 Other real estate owned income — 3 1 — — — 1 — — Net interest income 650 688 662 485 489 485 512 512 508 Total income less interest expense $ 808 $ 838 $ 810 $ 618 $ 627 $ 611 $ 608 $ 600 $ 590 NBAZ NSB Vectra (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Commercial account fees $ 7 $ 7 $ 7 $ 8 $ 8 $ 9 $ 6 $ 6 $ 6 Card fees 9 11 11 10 12 12 5 6 6 Retail and business banking fees 8 8 9 9 11 10 4 5 4 Capital markets and foreign exchange fees — — — — — — — — — Wealth management and trust fees 3 2 2 3 3 3 4 2 2 Other customer-related fees 1 1 1 1 1 1 — — — Total noninterest income from contracts with customers (ASC 606) 28 29 30 31 35 35 19 19 18 Other noninterest income (Non-ASC 606 customer related) 12 12 9 12 8 6 13 7 6 Total customer-related fees 40 41 39 43 43 41 32 26 24 Other noninterest income (noncustomer-related) 1 1 — — — — — — — Total noninterest income 41 42 39 43 43 41 32 26 24 Other real estate owned income — — — — 1 — — — — Net interest income 216 223 216 146 148 142 135 135 130 Total income less interest expense $ 257 $ 265 $ 255 $ 189 $ 192 $ 183 $ 167 $ 161 $ 154 TCBW Other Consolidated Bank (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Commercial account fees $ 1 $ 2 $ 2 $ 2 $ — $ — $ 125 $ 121 $ 122 Card fees 1 1 2 1 2 — 113 127 125 Retail and business banking fees — — — — 1 1 68 78 78 Capital markets and foreign exchange fees — — — 8 7 6 12 13 12 Wealth management and trust fees 1 1 — 1 16 14 59 57 51 Other customer-related fees — — — 19 11 16 25 18 24 Total noninterest income from contracts with customers (ASC 606) 3 4 4 31 37 37 402 414 412 Other noninterest income (Non-ASC 606 customer related) 2 1 1 15 3 10 147 111 96 Total customer-related fees 5 5 5 46 40 47 549 525 508 Other noninterest income (noncustomer-related) — — — 21 33 41 25 37 44 Total noninterest income 5 5 5 67 73 88 574 562 552 Other real estate owned income — — — — — — 1 4 1 Net interest income 52 53 52 20 24 35 2,216 2,272 2,230 Total income less interest expense $ 57 $ 58 $ 57 $ 87 $ 97 $ 123 $ 2,791 $ 2,838 $ 2,783

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan	The following schedule presents the change in benefit obligation, change in fair value of plan assets, and funded status, of the plans and amounts recognized in the balance sheet as of the measurement date of December 31: Pension Supplemental Post-retirement (In millions) 2020 2019 2020 2019 2020 2019 Change in benefit obligation: Benefit obligation at beginning of year $ 140 $ 138 $ 8 $ 9 $ 1 $ 1 Interest cost 1 5 — — — — Actuarial loss 13 8 1 — — — Annuity purchase (97) — — — — — Benefits paid (57) (11) (1) (1) — — Benefit obligation at end of year — 140 8 8 1 1 Change in fair value of plan assets: Fair value of plan assets at beginning of year 171 157 — — — — Actual return on plan assets 4 25 — — — — Employer contributions (21) — 1 1 — — Annuity purchase (97) — — — — — Benefits paid (57) (11) (1) (1) — — Fair value of plan assets at end of year — 171 — — — — Funded status $ — $ 31 $ (8) $ (8) $ (1) $ (1) Amounts recognized in balance sheet: Asset (liability) for pension/postretirement benefits $ — $ 31 $ (8) $ (8) $ (1) $ (1) Accumulated other comprehensive income (loss) — (17) (3) (2) — —
Schedule of Components of Net Periodic Benefit Cost (Credit)	The following schedule presents the components of net periodic benefit cost (credit) for the plans: Pension Supplemental Post-retirement (In millions) 2020 2019 2018 2020 2019 2018 2020 2019 2018 Interest cost $ 1 $ 5 $ 6 $ — $ — $ — $ — $ — $ — Expected return on plan assets (2) (9) (11) — — — — — — Amortization of net actuarial loss — — 1 — — — — — — Settlement loss 28 1 1 — — — — — — Net periodic benefit cost $ 27 $ (3) $ (3) $ — $ — $ — $ — $ — $ —
Schedule Of Weighted Average Assumptions Based On The Pension Plan	Weighted average assumptions based on the pension plan are the same where applicable for each of the plans and are as follows: 2020 2019 2018 Used to determine benefit obligation at year-end: Discount rate 1.85 % 3.20 % 4.20 % Used to determine net periodic benefit cost for the years ended December 31: Discount rate NA 4.20 3.50 Expected long-term return on plan assets NA 5.25 5.75
Schedule of Expected Benefit Payments	Benefit payments to the plans’ participants are estimated in the following schedule for the years succeeding December 31, 2020. (In millions) Supplemental Post-retirement 2021 $ 2 $ — 2022 1 — 2023 1 — 2024 1 — 2025 1 — Years 2026 – 2030 2 —
Retirement Plans, Unfunded Commitments and Redemption	The following presents additional information as of December 31, 2019 for the pooled separate accounts and limited partnerships whose fair values under Levels 2 and 3 are based on NAV per share: Investment Unfunded commitments (in millions, approximately) Redemption Frequency Notice period Pooled separate accounts NA Daily < $1 million, 1 day
Schedule of Changes in Plan Assets Measured at Fair Value on a Recurring Basis Using Level 3 Inputs	The following reconciles the beginning and ending balances of assets measured at fair value on a recurring basis using Level 3 inputs: Guaranteed deposit account Year Ended December 31, (In millions) 2020 2019 Balance at beginning of year $ 5 $ 12 Purchases 151 4 Sales (156) (11) Balance at end of year $ — $ 5

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Compensation Expense and Related Tax Benefit for All Share-Based Awards	Compensation expense and the related tax benefit for all share-based awards were as follows: (In millions) 2020 2019 2018 Compensation expense $ 26 $ 27 $ 26 Reduction of income tax expense 8 11 14
Summary of Weighted Average Value at Grant Date and the Significant Assumptions Used in Applying the Black-Scholes Model for Options Granted	The following summarizes the weighted average value at grant date and the significant assumptions used in applying the Black-Scholes model for options granted: 2020 2019 2018 Weighted average value for options granted $ 8.18 $ 10.30 $ 12.64 Weighted average assumptions used: Expected dividend yield 3.0 % 2.5 % 2.0 % Expected volatility 27.0 % 26.0 % 27.5 % Risk-free interest rate 1.38 % 2.52 % 2.62 % Expected life (in years) 5.0 5.0 5.0
Summary of Stock Option Activity	The following summarizes our stock option activity for the three years ended December 31, 2020: Number of shares Weighted average exercise price Balance at December 31, 2017 2,560,571 $ 27.06 Granted 194,001 55.13 Exercised (729,346) 26.79 Expired (2,000) 25.74 Forfeited (18,628) 31.11 Balance at December 31, 2018 2,004,598 29.85 Granted 256,818 50.80 Exercised (569,808) 24.61 Expired (4,330) 22.37 Forfeited (10,500) 43.13 Balance at December 31, 2019 1,676,778 34.77 Granted 320,913 45.61 Exercised (285,954) 26.48 Expired (22,685) 30.17 Forfeited (5,395) 51.34 Balance at December 31, 2020 1,683,657 38.26 Outstanding stock options exercisable as of: December 31, 2020 1,137,596 $ 33.42 December 31, 2019 1,239,821 28.95 December 31, 2018 1,448,244 26.68
Summary of Additional Selected Information on Stock Options	Additional selected information on stock options at December 31, 2020 follows: Outstanding stock options Exercisable stock options Exercise price range Number of shares Weighted average exercise price Weighted average remaining contractual life (years) Number of shares Weighted average exercise price $4.15 to $19.99 10,867 $ 6.22 1 10,867 $ 6.22 $20.00 to $24.99 276,809 21.03 2.1 276,809 21.03 $25.00 to $29.99 450,709 28.53 1.1 450,031 28.53 $30.00 to $39.99 22,225 30.10 0.4 22,225 30.10 $40.00 to $44.99 173,351 44.10 3.0 171,290 44.12 $45.00 to $49.99 318,954 45.65 6.1 — — $50.00 to $55.68 430,742 52.90 4.5 206,374 53.58 1,683,657 38.26 1 3.3 1,137,596 33.42 1 The weighted average remaining contractual life excludes 10,867 stock options without a fixed expiration date that were assumed with the Amegy acquisition. They expire between the date of termination and one year from the date of termination, depending upon certain circumstances.
Summary of Nonvested Restricted Stock Activity	The following summarizes our restricted stock activity for the three years ended December 31, 2020: Number of shares Weighted average fair value Nonvested restricted shares at December 31, 2017 38,978 $ 25.91 Issued 21,634 42.90 Vested (14,836) 26.27 Forfeited (90) 55.68 Nonvested restricted shares at December 31, 2018 45,686 33.78 Issued 24,994 42.83 Vested (20,223) 30.69 Nonvested restricted shares at December 31, 2019 50,457 39.50 Issued 27,798 45.65 Vested (20,859) 34.77 Nonvested restricted shares at December 31, 2020 57,396 44.20
Summary of RSU Activity	The following summarizes our RSU activity for the three years ended December 31, 2020: Number of restricted stock units Weighted average fair value Restricted stock units at December 31, 2017 1,709,813 $ 30.08 Granted 461,305 53.17 Vested (699,920) 29.56 Forfeited (70,499) 35.95 Restricted stock units at December 31, 2018 1,400,699 37.65 Granted 536,489 47.85 Vested (614,968) 33.74 Forfeited (28,150) 44.69 Restricted stock units at December 31, 2019 1,294,070 43.59 Granted 586,302 42.75 Vested (593,375) 37.56 Forfeited (44,676) 47.78 Restricted stock units at December 31, 2020 1,242,321 46.31

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income Tax Expense (Benefit)	Income tax expense is summarized as follows: (In millions) 2020 2019 2018 Federal: Current $ 153 $ 195 $ 210 Deferred (47) (1) (1) Total Federal 106 194 209 State: Current 38 44 49 Deferred (11) (1) 1 Total State 27 43 50 Total $ 133 $ 237 $ 259
Schedule of Statutory Federal Income Tax Rate Reconciles to Actual Income Tax Expense (Benefit)	(In millions) 2020 2019 2018 Income tax expense at statutory federal rate $ 141 $ 221 $ 240 State income taxes including credits, net 21 34 40 Other nondeductible expenses 8 13 15 Nontaxable income (32) (28) (24) Share-based compensation (1) (4) (7) Tax credits and other taxes (4) 1 (5) Total $ 133 $ 237 $ 259
Schedule of Tax Effects of Deferred Tax Assets and Deferred Tax Liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets (“DTA”) and deferred tax liabilities (“DTL”) are presented below: (In millions) December 31, 2020 2019 Gross deferred tax assets: Book loan loss deduction in excess of tax $ 205 $ 137 Pension and postretirement 1 5 Deferred compensation 71 72 Lease liabilities 59 61 Other 24 35 Total deferred tax assets before valuation allowance 360 310 Valuation allowance — — Total deferred tax assets 360 310 Gross deferred tax liabilities: Premises and equipment, due to differences in depreciation (81) (66) Federal Home Loan Bank stock dividends (2) (2) Leasing operations (55) (52) Prepaid expenses (6) (6) Prepaid pension reserves (6) (12) Mortgage servicing (8) (7) Security investments and derivative fair value adjustments (102) (17) Deferred loan fees (32) (30) ROU assets (53) (55) Equity investments (18) (26) Total deferred tax liabilities (363) (273) Net deferred tax assets (liabilities) $ (3) $ 37
Schedule of Reconciliation of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: (In millions) 2020 2019 2018 Balance at beginning of year $ 14 $ 8 $ 6 Tax positions related to current year: Additions 2 2 1 Reductions — — — Tax positions related to prior years: Additions — 4 1 Reductions (5) — — Settlements with taxing authorities — — — Lapses in statutes of limitations — — — Balance at end of year $ 11 $ 14 $ 8

Net Earnings Per Common Share (

Net Earnings Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Diluted, by Common Class, Including Two Class Method	Basic and diluted net earnings per common share based on the weighted average outstanding shares are summarized as follows: (In millions, except shares and per share amounts) 2020 2019 2018 Basic: Net income $ 539 $ 816 $ 884 Less common and preferred dividends 259 260 236 Undistributed earnings 280 556 648 Less undistributed earnings applicable to nonvested shares 2 4 5 Undistributed earnings applicable to common shares 278 552 643 Distributed earnings applicable to common shares 223 224 200 Total earnings applicable to common shares $ 501 $ 776 $ 843 Weighted average common shares outstanding (in thousands) 163,737 175,984 193,589 Net earnings per common share $ 3.06 $ 4.41 $ 4.36 Diluted: Total earnings applicable to common shares $ 501 $ 776 $ 843 Weighted average common shares outstanding (in thousands) 163,737 175,984 193,589 Dilutive effect of common stock warrants (in thousands) 1,641 9,926 11,959 Dilutive effect of stock options (in thousands) 235 594 953 Weighted average diluted common shares outstanding (in thousands) 165,613 186,504 206,501 Net earnings per common share $ 3.02 $ 4.16 $ 4.08
Schedule of Weighted Average Number of Shares	The following schedule presents the weighted average stock awards that were anti-dilutive and not included in the calculation of diluted earnings per share. (In thousands) 2020 2019 2018 Restricted stock and restricted stock units $ 1,338 $ 1,390 $ 1,602 Stock options 889 460 151

Operating Segment Information (

Operating Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following schedule presents selected operating segment information: (In millions) Zions Bank Amegy CB&T 2020 2019 2018 2020 2019 2018 2020 2019 2018 SELECTED INCOME STATEMENT DATA Net interest income $ 650 $ 688 $ 662 $ 485 $ 489 $ 485 $ 512 $ 512 $ 508 Provision for credit losses 67 18 8 111 9 (80) 120 7 15 Net interest income after provision for credit losses 583 670 654 374 480 565 392 505 493 Noninterest income 158 147 147 133 138 126 95 88 82 Noninterest expense 446 471 460 329 344 344 305 316 308 Income before income taxes $ 295 $ 346 $ 341 $ 178 $ 274 $ 347 $ 182 $ 277 $ 267 SELECTED AVERAGE BALANCE SHEET DATA Total average loans $ 13,845 $ 13,109 $ 12,643 $ 13,114 $ 12,235 $ 11,358 $ 12,366 $ 10,763 $ 10,033 Total average deposits 18,370 15,561 15,149 12,970 11,627 11,160 13,763 11,522 11,268 (In millions) NBAZ NSB Vectra 2020 2019 2018 2020 2019 2018 2020 2019 2018 SELECTED INCOME STATEMENT DATA Net interest income $ 216 $ 223 $ 216 $ 146 $ 148 $ 142 $ 135 $ 135 $ 130 Provision for credit losses 35 2 8 37 (1) 1 34 3 6 Net interest income after provision for credit losses 181 221 208 109 149 141 101 132 124 Noninterest income 41 42 39 43 43 41 32 26 24 Noninterest expense 147 156 152 141 145 143 109 108 105 Income before income taxes $ 75 $ 107 $ 95 $ 11 $ 47 $ 39 $ 24 $ 50 $ 43 SELECTED AVERAGE BALANCE SHEET DATA Total average loans $ 5,099 $ 4,774 $ 4,608 $ 3,102 $ 2,630 $ 2,394 $ 3,401 $ 3,109 $ 2,924 Total average deposits 5,771 5,002 4,931 5,427 4,512 4,286 3,637 2,853 2,761 (In millions) TCBW Other Consolidated Bank 2020 2019 2018 2020 2019 2018 2020 2019 2018 SELECTED INCOME STATEMENT DATA Net interest income $ 52 $ 53 $ 52 $ 20 $ 24 $ 35 $ 2,216 $ 2,272 $ 2,230 Provision for credit losses 7 (1) 2 3 2 — 414 39 (40) Net interest income after provision for credit losses 45 54 50 17 22 35 1,802 2,233 2,270 Noninterest income 5 5 5 67 73 88 574 562 552 Noninterest expense 22 22 22 205 180 145 1,704 1,742 1,679 Income (loss) before income taxes $ 28 $ 37 $ 33 $ (121) $ (85) $ (22) $ 672 $ 1,053 $ 1,143 SELECTED AVERAGE BALANCE SHEET DATA Total average loans $ 1,460 $ 1,194 $ 1,118 $ 629 $ 451 $ 347 $ 53,016 $ 48,265 $ 45,425 Total average deposits 1,256 1,094 1,092 2,495 2,910 2,536 63,689 55,081 53,183

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of Financial Information by Quarter	Financial information by quarter for 2020 and 2019 is shown below. Certain prior period amounts have been reclassified to conform with the current year presentation. These reclassifications did not affect net income. See related discussion in Note 1. (In millions, except per share amounts) Fourth Quarter Third Quarter Second Quarter First Quarter 2020 Gross interest income $ 571 $ 581 $ 595 $ 622 Net interest income 550 555 563 548 Provision for credit losses (67) 55 168 258 Noninterest income 166 157 117 134 Noninterest expense 424 442 430 408 Income before income taxes 359 215 82 16 Net income 284 175 66 14 Preferred stock dividends (9) (8) (9) (8) Net earnings applicable to common shareholders 275 167 57 6 Net earnings per common share: Basic 1.66 1.01 0.34 0.04 Diluted 1.66 1.01 0.34 0.04 2019 Gross interest income $ 647 $ 677 $ 684 $ 675 Net interest income 559 567 569 576 Provision for credit losses 4 10 21 4 Noninterest income 152 146 132 132 Noninterest expense 472 415 424 430 Income before income taxes 235 288 256 274 Net income 183 222 198 213 Preferred stock dividends (9) (8) (9) (8) Net earnings applicable to common shareholders 174 214 189 205 Net earnings per common share: Basic 1.03 1.23 1.05 1.10 Diluted 0.97 1.17 0.99 1.04

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) $ in Billions	12 Months Ended
	Dec. 31, 2020USD ($)statesegment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of states in which entity operates | state	11
Number of community regional banks operating in distinct geographical areas | segment	7
Percentage of agreements with minimum maturity period	28.00%
Percentage of agreements with maximum maturity period	0.00%
Securities for which entity has right to sell or repledge	$ 5.7
Security resell agreements average amount	2.1
Security resell agreements maximum amount, outstanding	$ 6.4
Percentage of acquired assets and all assumed liabilities recognized in business combination	100.00%
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Security resell agreements maturity (in days)	30 days
Minimum | Building
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of properties (in years)	25 years
Minimum | Furniture and Equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of properties (in years)	3 years
Minimum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of properties (in years)	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Security resell agreements maturity (in days)	50 days
Maximum | Building
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of properties (in years)	40 years
Maximum | Furniture and Equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of properties (in years)	10 years
Maximum | Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives of properties (in years)	10 years

Recent Accounting Pronounceme_3

Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 7,886		$ 7,353	$ 7,578	$ 7,679
Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent	$ 4,309		4,009	3,456	2,807
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent			20	(3)	1
Cumulative Effect, Period of Adoption, Adjustment | Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent			$ 20	$ (3)	$ 1
Cumulative Effect, Period of Adoption, Adjustment | ASU 2016-13 | Retained earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent		$ 20

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Net gains on sale of OREO properties	$ 1	$ 4	$ 1
Other noninterest-bearing investments valued under the cost method	8	8
Federal Reserve and Federal Home Loan Bank Stock	109	157
Private equity investments accounted for under the equity method	61	45
OREO properties
Derivatives, Fair Value [Line Items]
Net gains on sale of OREO properties	1	3
Carrying value of OREO properties	$ 6	$ 5
Level 2
Derivatives, Fair Value [Line Items]
AFS securities with fair value measured by a third party pricing service (as a percent)	95.00%

Fair Value (Schedule of Assets

Fair Value (Schedule of Assets and Liabilities Measured at Fair Value by Class on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Investment securities, available-for-sale	$ 15,731	$ 13,725
Trading account	266	182
Total Assets	17,160	14,832
LIABILITIES
Securities sold, not yet purchased	61	66
Total Liabilities	99	85
U.S. Treasury, agencies and corporations
ASSETS
Investment securities, available-for-sale	14,136	12,381
Municipal securities
ASSETS
Investment securities, available-for-sale	1,420	1,319
Other debt securities
ASSETS
Investment securities, available-for-sale	175	25
Bank-owned life insurance
ASSETS
Other noninterest-bearing investments	532	525
Private equity investments
ASSETS
Other noninterest-bearing investments	80	116
Agriculture loan servicing and interest-only strips
ASSETS
Other assets	16	18
Interest rate
ASSETS
Other assets	411	149
LIABILITIES
Other liabilities	34	15
Foreign exchange
ASSETS
Other assets	4	4
LIABILITIES
Other liabilities	4	4
Level 1
ASSETS
Investment securities, available-for-sale	192	25
Trading account	111	65
Total Assets	427	216
LIABILITIES
Securities sold, not yet purchased	61	66
Total Liabilities	65	70
Level 1 | U.S. Treasury, agencies and corporations
ASSETS
Investment securities, available-for-sale	192	25
Level 1 | Private equity investments
ASSETS
Other noninterest-bearing investments		9
Level 1 | Foreign exchange
ASSETS
Other assets	4	4
LIABILITIES
Other liabilities	4	4
Level 2
ASSETS
Investment securities, available-for-sale	15,539	13,700
Trading account	155	117
Total Assets	16,637	14,491
LIABILITIES
Securities sold, not yet purchased	0	0
Total Liabilities	34	15
Level 2 | U.S. Treasury, agencies and corporations
ASSETS
Investment securities, available-for-sale	13,944	12,356
Level 2 | Municipal securities
ASSETS
Investment securities, available-for-sale	1,420	1,319
Level 2 | Other debt securities
ASSETS
Investment securities, available-for-sale	175	25
Level 2 | Bank-owned life insurance
ASSETS
Other noninterest-bearing investments	532	525
Level 2 | Interest rate
ASSETS
Other assets	411	149
LIABILITIES
Other liabilities	34	15
Level 3
ASSETS
Investment securities, available-for-sale	0	0
Total Assets	96	125
LIABILITIES
Securities sold, not yet purchased	0	0
Total Liabilities	0	0
Level 3 | U.S. Treasury, agencies and corporations
ASSETS
Investment securities, available-for-sale	0	0
Level 3 | Private equity investments
ASSETS
Other noninterest-bearing investments	80	107
Level 3 | Agriculture loan servicing and interest-only strips
ASSETS
Other assets	16	18
Deferred compensation plan assets | Deferred compensation plan assets
ASSETS
Other assets	120	113
Deferred compensation plan assets | Level 1 | Deferred compensation plan assets
ASSETS
Other assets	$ 120	$ 113

Fair Value (Schedule of Asset_2

Fair Value (Schedule of Assets and Liabilities Measured at Fair Value by Class on a Recurring Basis Using Level 3 Inputs) (Details) - Level 3 - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Private equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year	$ 107	$ 102
Securities gains (losses), net	(5)	2
Other noninterest income (expense)	0	0
Purchases	9	10
Redemptions and paydowns	0	0
Other	(31)	(7)
Balance at end of year	80	107
Ag loan svcg and int-only strips
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year	18	18
Securities gains (losses), net	0	0
Other noninterest income (expense)	(1)	1
Purchases	0	0
Redemptions and paydowns	(1)	(1)
Other	0	0
Balance at end of year	$ 16	$ 18

Fair Value (Schedule of Realize

Fair Value (Schedule of Realized Gains (Losses) Using Level 3 Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities gains (losses), net	$ 18	$ (9)

Fair Value (Schedule of Asset_3

Fair Value (Schedule of Assets With Fair Value Changes on Nonrecurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	$ 17,160	$ 14,832
Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	16	1
Gain (losses) from fair value changes	(17)	(2)
Private equity investments, carried at cost | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	1	1
Gain (losses) from fair value changes	(1)	(1)
Collateral-dependent loans | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	14	0
Gain (losses) from fair value changes	(14)	0
Other real estate owned | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	1	0
Gain (losses) from fair value changes	(2)	(1)
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	427	216
Level 1 | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	0	0
Level 1 | Private equity investments, carried at cost | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	0	0
Level 1 | Collateral-dependent loans | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	0	0
Level 1 | Other real estate owned | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	0	0
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	16,637	14,491
Level 2 | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	15	0
Level 2 | Private equity investments, carried at cost | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	0	0
Level 2 | Collateral-dependent loans | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	14	0
Level 2 | Other real estate owned | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	1	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	96	125
Level 3 | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	1	1
Level 3 | Private equity investments, carried at cost | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	1	1
Level 3 | Collateral-dependent loans | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	0	0
Level 3 | Other real estate owned | Fair Value, Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value	$ 0	$ 0

Fair Value (Schedule of Carryin

Fair Value (Schedule of Carrying Values and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	$ 640	$ 597
Time deposits	2,588	4,719
Long-term debt	1,336	1,723
Level 2 | Carrying value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	636	592
Time deposits	2,588	4,719
Long-term debt	1,336	1,723
Level 2 | Estimated fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held-to-maturity investment securities	640	597
Time deposits	2,603	4,725
Long-term debt	1,346	1,751
Level 3 | Carrying value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases (including loans held for sale), net of allowance	52,780	48,343
Level 3 | Estimated fair value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans and leases (including loans held for sale), net of allowance	$ 53,221	$ 47,958

Offsetting Assets and Liabili_3

Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Offsetting [Abstract]
Federal funds sold and security resell agreements, Gross amounts recognized	$ 6,457	$ 694
Federal funds sold and security resell agreements, Gross amounts offset in the balance sheet	(692)	(210)
Federal funds sold and security resell agreements, Net amounts presented in balance sheet	5,765	484
Federal funds sold and security resell agreements, financial instruments	0	0
Federal funds sold and security resell agreements, cash collateral received/pledged	0	0
Federal funds sold and security resell agreements, Net amount	5,765	484
Derivative assets, Gross amounts recognized	418	153
Derivative assets, Gross amounts offset in the balance sheet	0	0
Derivative assets, Net amounts presented in balance sheet	418	153
Derivatives asset, Financial instruments	(6)	(6)
Derivatives asset, Cash collateral received/pledged	(3)	0
Derivative assets, Net amount	409	147
Total assets, Gross amounts recognized	6,875	847
Total assets, Gross amounts offset in the balance sheet	(692)	(210)
Total assets, Net amounts presented in the balance sheet	6,183	637
Total assets, Financial instruments	(6)	(6)
Total assets, Cash collateral received/pledged	(3)	0
Total assets, Net amounts	6,174	631
Federal funds purchased and other short-term borrowings, Gross amounts recognized	2,264	2,263
Federal funds purchased and other short-term borrowings, Gross amounts offset in balance sheet	(692)	(210)
Federal funds purchased and other short-term borrowings, Net amounts presented in balance sheet	1,572	2,053
Federal funds purchased and other short-term borrowings, Financial instruments	0	0
Federal funds purchased and other short-term borrowings, Cash collateral received/pledged	0	0
Federal funds purchased and other short-term borrowings, Net amount	1,572	2,053
Derivative liabilities, Gross amounts recognized	38	19
Derivative liabilities, Gross amounts offset in balance sheet	0	0
Derivative liabilities, Net amounts presented in balance sheet	38	19
Derivative liabilities, Financial instrument	(6)	(6)
Derivative liabilities, Cash collateral received/pledged	(26)	(10)
Derivative liabilities, Net amount	6	3
Total liabilities, Gross amounts recognized	2,302	2,282
Total liabilities, Gross amounts offset in balance sheet	(692)	(210)
Total liabilities, Net amounts presented in the balance sheet	1,610	2,072
Total liabilities, Financial instruments	(6)	(6)
Total liabilities, Cash collateral received/pledged	(26)	(10)
Total liabilities, Net amount	$ 1,578	$ 2,056

Investments (Narrative) (Detail

Investments (Narrative) (Details) $ in Millions	Dec. 31, 2020USD ($)security	Dec. 31, 2019USD ($)security
Debt and Equity Securities, FV-NI [Line Items]
Accrued interest receivable	$ 200	$ 164
Number of HTM investment securities in an unrealized loss position | security	119	146
Number of AFS investment securities in an unrealized loss position | security	549	849
Allowance for credit loss on HTM securities	$ 1
Carrying value of pledged securities	2,300	$ 2,000
Securities Investment
Debt and Equity Securities, FV-NI [Line Items]
Accrued interest receivable	$ 54	$ 58

Investments (Summary of Investm

Investments (Summary of Investment Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Marketable Securities [Line Items]
Available-for-sale, Amortized cost	$ 15,417	$ 13,686
Total investment securities, Amortized cost	16,053	14,278
Available-for-sale, Gross unrealized gains	370	126
Total investment securities, Gross unrealized gains	375	131
Available-for-sale, Gross unrealized losses	56	87
Total investment securities, Gross unrealized losses	57	87
Held-to-maturity investment securities	640	597
Available-for-sale, at fair value	15,731	13,725
Total investment securities, Estimated fair value	16,371	14,322
Municipal securities
Marketable Securities [Line Items]
Held-to-maturity, Amortized cost	636	592
Available-for-sale, Amortized cost	1,352	1,282
Held-to-maturity, Gross unrealized gains	5	5
Available-for-sale, Gross unrealized gains	68	37
Held-to-maturity, Gross unrealized losses	1	0
Available-for-sale, Gross unrealized losses	0	0
Held-to-maturity investment securities	640	597
Available-for-sale, at fair value	1,420	1,319
U.S. Treasury securities
Marketable Securities [Line Items]
Available-for-sale, Amortized cost	205	25
Available-for-sale, Gross unrealized gains	0	0
Available-for-sale, Gross unrealized losses	13	0
Available-for-sale, at fair value	192	25
Agency securities
Marketable Securities [Line Items]
Available-for-sale, Amortized cost	1,051	1,301
Available-for-sale, Gross unrealized gains	40	5
Available-for-sale, Gross unrealized losses	0	4
Available-for-sale, at fair value	1,091	1,302
Agency guaranteed mortgage-backed securities
Marketable Securities [Line Items]
Available-for-sale, Amortized cost	11,439	9,518
Available-for-sale, Gross unrealized gains	262	83
Available-for-sale, Gross unrealized losses	8	42
Available-for-sale, at fair value	11,693	9,559
Small Business Administration loan-backed securities
Marketable Securities [Line Items]
Available-for-sale, Amortized cost	1,195	1,535
Available-for-sale, Gross unrealized gains	0	1
Available-for-sale, Gross unrealized losses	35	41
Available-for-sale, at fair value	1,160	1,495
Other debt securities
Marketable Securities [Line Items]
Available-for-sale, Amortized cost	175	25
Available-for-sale, Gross unrealized gains	0	0
Available-for-sale, Gross unrealized losses	0	0
Available-for-sale, at fair value	$ 175	$ 25

Investments (Contractual Maturi

Investments (Contractual Maturities Debt Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Available-for-sale, Amortized cost
Total debt investment securities	$ 15,417	$ 13,686
Due in one year or less	149
Due after one year through five years	1,347
Due after five years through 10 years	1,695
Due after 10 years	$ 12,226
Available-for-sale, Weighted average yield
Total debt investment securities	1.91%
Due in one year or less	1.24%
Due after one year through five years	1.96%
Due after five years through 10 years	2.01%
Due after 10 years	1.89%
Total investment securities, Amortized cost
Total debt investment securities	$ 16,053	$ 14,278
Due in one year or less	295
Due after one year through five years	1,534
Due after five years through 10 years	1,869
Due after 10 years	$ 12,355
Total investment securities, Weighted average yield
Total debt investment securities	1.95%
Due in one year or less	1.64%
Due after one year through five years	2.14%
Due after five years through 10 years	2.12%
Due after 10 years	1.91%
Municipal securities
Held-to-maturity, Amortized cost
Total debt investment securities	$ 636
Due in one year or less	146
Due after one year through five years	187
Due after five years through 10 years	174
Due after 10 years	$ 129
Held-to-maturity, Weighted average yield
Total debt investment securities	3.08%
Due in one year or less	2.05%
Due after one year through five years	3.42%
Due after five years through 10 years	3.19%
Due after 10 years	3.58%
Available-for-sale, Amortized cost
Total debt investment securities	$ 1,352
Due in one year or less	99
Due after one year through five years	640
Due after five years through 10 years	432
Due after 10 years	$ 181
Available-for-sale, Weighted average yield
Total debt investment securities	2.44%
Due in one year or less	1.83%
Due after one year through five years	2.39%
Due after five years through 10 years	2.60%
Due after 10 years	2.59%
U.S. Treasury securities
Available-for-sale, Amortized cost
Total debt investment securities	$ 205
Due in one year or less	50
Due after one year through five years	0
Due after five years through 10 years	0
Due after 10 years	$ 155
Available-for-sale, Weighted average yield
Total debt investment securities	0.99%
Due in one year or less	0.09%
Due after one year through five years	0.00%
Due after five years through 10 years	0.00%
Due after 10 years	1.28%
Agency securities
Available-for-sale, Amortized cost
Total debt investment securities	$ 1,051
Due in one year or less	0
Due after one year through five years	292
Due after five years through 10 years	238
Due after 10 years	$ 521
Available-for-sale, Weighted average yield
Total debt investment securities	2.36%
Due in one year or less	0.00%
Due after one year through five years	1.73%
Due after five years through 10 years	2.65%
Due after 10 years	2.58%
Agency guaranteed mortgage-backed securities
Available-for-sale, Amortized cost
Total debt investment securities	$ 11,439
Due in one year or less	0
Due after one year through five years	372
Due after five years through 10 years	728
Due after 10 years	$ 10,339
Available-for-sale, Weighted average yield
Total debt investment securities	1.87%
Due in one year or less	0.00%
Due after one year through five years	1.48%
Due after five years through 10 years	1.77%
Due after 10 years	1.89%
Small Business Administration loan-backed securities
Available-for-sale, Amortized cost
Total debt investment securities	$ 1,195
Due in one year or less	0
Due after one year through five years	43
Due after five years through 10 years	137
Due after 10 years	$ 1,015
Available-for-sale, Weighted average yield
Total debt investment securities	1.56%
Due in one year or less	0.00%
Due after one year through five years	1.39%
Due after five years through 10 years	1.61%
Due after 10 years	1.56%
Other debt securities
Available-for-sale, Amortized cost
Total debt investment securities	$ 175
Due in one year or less	0
Due after one year through five years	0
Due after five years through 10 years	160
Due after 10 years	$ 15
Available-for-sale, Weighted average yield
Total debt investment securities	1.05%
Due in one year or less	0.00%
Due after one year through five years	0.00%
Due after five years through 10 years	0.87%
Due after 10 years	2.93%

Investments (Summary of Amount

Investments (Summary of Amount of Gross Unrealized Losses for Debt Securities and Estimated Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Total investment securities, gross unrealized losses, less than 12 months	$ 21	$ 7
Total investment securities, estimated fair value, less than 12 months	1,625	1,690
Total investment securities, gross unrealized losses, 12 months or more	36	80
Total investment securities, estimated fair value, 12 months or more	1,261	4,839
Total investment securities, gross unrealized losses, total	57	87
Total investment securities, estimated fair value, total	2,886	6,529
Municipal securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Held-to-maturity, Less than 12 months - Gross unrealized losses	1	0
Available-for-sale, Less than 12 months - Gross unrealized losses	0	0
Held-to-maturity, Less than 12 months - Estimated fair value	96	73
Available-for-sale, estimated fair value, less than 12 Months	19	50
Held-to-maturity, 12 months or more - Gross unrealized losses	0	0
Available-for-sale, 12 months or more - Gross unrealized losses	0	0
Held-to-maturity, 12 months or more - Estimated fair value	12	45
Available-for-sale, estimated fair value, 12 months or more	0	5
Held-to-maturity, Total - Gross unrealized losses	1	0
Available-for-sale, Total - Gross unrealized losses	0	0
Held-to-maturity, Total - Estimated fair value	108	118
Available-for-sale, estimated fair value, total	19	55
U.S. Treasury securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Available-for-sale, Less than 12 months - Gross unrealized losses	13
Available-for-sale, estimated fair value, less than 12 Months	142
Available-for-sale, 12 months or more - Gross unrealized losses	0
Available-for-sale, estimated fair value, 12 months or more	0
Available-for-sale, Total - Gross unrealized losses	13
Available-for-sale, estimated fair value, total	142
Agency securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Available-for-sale, Less than 12 months - Gross unrealized losses	0	2
Available-for-sale, estimated fair value, less than 12 Months	6	222
Available-for-sale, 12 months or more - Gross unrealized losses	0	2
Available-for-sale, estimated fair value, 12 months or more	2	359
Available-for-sale, Total - Gross unrealized losses	0	4
Available-for-sale, estimated fair value, total	8	581
Agency guaranteed mortgage-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Available-for-sale, Less than 12 months - Gross unrealized losses	7	4
Available-for-sale, estimated fair value, less than 12 Months	1,197	1,173
Available-for-sale, 12 months or more - Gross unrealized losses	1	38
Available-for-sale, estimated fair value, 12 months or more	179	3,215
Available-for-sale, Total - Gross unrealized losses	8	42
Available-for-sale, estimated fair value, total	1,376	4,388
Small Business Administration loan-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Available-for-sale, Less than 12 months - Gross unrealized losses	0	1
Available-for-sale, estimated fair value, less than 12 Months	15	172
Available-for-sale, 12 months or more - Gross unrealized losses	35	40
Available-for-sale, estimated fair value, 12 months or more	1,068	1,215
Available-for-sale, Total - Gross unrealized losses	35	41
Available-for-sale, estimated fair value, total	1,083	1,387
Other
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Available-for-sale, Less than 12 months - Gross unrealized losses	0	0
Available-for-sale, estimated fair value, less than 12 Months	150	0
Available-for-sale, 12 months or more - Gross unrealized losses	0	0
Available-for-sale, estimated fair value, 12 months or more	0	0
Available-for-sale, Total - Gross unrealized losses	0	0
Available-for-sale, estimated fair value, total	150	0
Available-for-sale
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Available-for-sale, Less than 12 months - Gross unrealized losses	20	7
Available-for-sale, estimated fair value, less than 12 Months	1,529	1,617
Available-for-sale, 12 months or more - Gross unrealized losses	36	80
Available-for-sale, estimated fair value, 12 months or more	1,249	4,794
Available-for-sale, Total - Gross unrealized losses	56	87
Available-for-sale, estimated fair value, total	$ 2,778	$ 6,411

Investments (HTM Year of Issuan

Investments (HTM Year of Issuance) (Details) $ in Millions	Dec. 31, 2020USD ($)
Investments [Abstract]
2020	$ 216
2019	18
2018	0
2017	12
2016	176
Prior	214
Total Securities	$ 636

Investments (Gains and Losses,

Investments (Gains and Losses, Including OTTI, Recognized in Statement of Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments [Abstract]
Other noninterest-bearing investments, Nonmarketable equity securities, Gross gains	$ 27	$ 20	$ 17
Other noninterest-bearing investments, Nonmarketable equity securities, Gross losses	20	17	16
Net gains (losses)	$ 7	$ 3	$ 1

Investments (Tax and Nontaxable

Investments (Tax and Nontaxable Income by Investment Type) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Investment Income [Line Items]
Interest income	$ 304	$ 362	$ 350
Taxable
Net Investment Income [Line Items]
Interest income	262	318	306
Nontaxable
Net Investment Income [Line Items]
Interest income	42	44	44
Held-to-maturity
Net Investment Income [Line Items]
Interest income	20	22	24
Held-to-maturity | Taxable
Net Investment Income [Line Items]
Interest income	10	9	10
Held-to-maturity | Nontaxable
Net Investment Income [Line Items]
Interest income	10	13	14
Available-for-sale
Net Investment Income [Line Items]
Interest income	277	333	321
Available-for-sale | Taxable
Net Investment Income [Line Items]
Interest income	252	308	295
Available-for-sale | Nontaxable
Net Investment Income [Line Items]
Interest income	25	25	26
Trading
Net Investment Income [Line Items]
Interest income	7	7	5
Trading | Taxable
Net Investment Income [Line Items]
Interest income	0	1	1
Trading | Nontaxable
Net Investment Income [Line Items]
Interest income	$ 7	$ 6	$ 4

Loans, Leases, and Allowance _3

Loans, Leases, and Allowance for Credit Losses (Summary of Major Portfolio Segment and Specific Loan Class) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	$ 81	$ 129
Total loans and leases	53,476	48,709
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	30,472	25,388
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	13,444	14,760
Commercial | Leasing
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	320	334
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	8,185	7,901
Commercial | Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,951	2,393
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	12,104	11,555
Commercial real estate | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,345	2,211
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	9,759	9,344
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	10,900	11,766
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	2,745	2,917
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	6,969	7,568
Consumer | Construction and other consumer real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	630	624
Consumer | Bankcard and other revolving plans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	432	502
Consumer | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans and leases	$ 124	$ 155

Loans, Leases, and Allowance _4

Loans, Leases, and Allowance for Credit Losses (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)mo	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Net unamortized purchase premiums, discounts, and deferred loan fees and cost	$ 149,000,000	$ 60,000,000
Accrued interest receivable	200,000,000	164,000,000
Loans	53,476,000,000	48,709,000,000
Carrying values of loans that have been pledged as collateral	24,700,000,000	21,500,000,000
Held-for-sale loans sold	1,800,000,000	872,000,000	$ 585,000,000
Payments for origination and purchases of loans held-for-sale	1,800,000,000	916,000,000	785,000,000
Principal balance of loans sold, serviced loans	2,800,000,000	1,700,000,000	2,200,000,000
Income from loans sold	54,000,000	18,000,000	$ 12,000,000
Financing receivable, commitments threshold for evaluating collectively or individually	$ 1,000,000
Financing receivable, minimum number of months for borrower to meet terms for TDR status | mo	6
Unfunded Lending Commitments on Troubled Debt Restructuring	$ 3,000,000	5,000,000
Recorded investment in TDR loans modified with interest rates below market	311,000,000	153,000,000
Real estate acquired through foreclosure	1,000,000	1,000,000
Mortgage loans in process of foreclosure	10,000,000	8,000,000
Doubtful
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	4,000,000	0
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	$ 12,104,000,000	11,555,000,000
Financing receivable, period once past due, charged off or charged down	180 days
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	$ 10,900,000,000	11,766,000,000
Financing receivable, period once past due, charged off or charged down	180 days
Interest Rate Below Market, Including Multiple Modification Types
Financing Receivable, Allowance for Credit Losses [Line Items]
Recorded investment in TDR loans modified with interest rates below market	$ 76,000,000	73,000,000
Land Acquisition and Development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans	$ 156,000,000	$ 158,000,000
Closed-End Consumer Loans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing receivable, period once past due, charged off or charged down	120 days

Loans, Leases, and Allowance _5

Loans, Leases, and Allowance for Credit Losses (Summary of Changes in the Allowance for Credit Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for loan losses
Balance at beginning of period	$ 495	$ 495
Provision for loan losses	385	37	$ (39)
Gross loan and lease charge-offs	128	78
Recoveries	23	41
Net loan and lease charge-offs (recoveries)	105	37
Balance at ending of period	777	495	495
Reserve for unfunded lending commitments
Balance at beginning of period	59	57
Provision for unfunded lending commitments	29	2	(1)
Balance at end of period	58	59	57
Total allowance for credit losses	835	554
Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses
Balance at beginning of period	2
Balance at ending of period		2
Reserve for unfunded lending commitments
Balance at beginning of period	(30)
Balance at end of period		(30)
Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses
Balance at beginning of period	497
Balance at ending of period		497
Reserve for unfunded lending commitments
Balance at beginning of period	29
Balance at end of period		29
Commercial
Allowance for loan losses
Balance at beginning of period	341	331
Provision for loan losses	281	42
Gross loan and lease charge-offs	113	57
Recoveries	14	25
Net loan and lease charge-offs (recoveries)	99	32
Balance at ending of period	464	341	331
Reserve for unfunded lending commitments
Balance at beginning of period	39	40
Provision for unfunded lending commitments	19	(1)
Balance at end of period	30	39	40
Total allowance for credit losses	494	380
Commercial | Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses
Balance at beginning of period	(59)
Balance at ending of period		(59)
Reserve for unfunded lending commitments
Balance at beginning of period	(28)
Balance at end of period		(28)
Commercial | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses
Balance at beginning of period	282
Balance at ending of period		282
Reserve for unfunded lending commitments
Balance at beginning of period	11
Balance at end of period		11
Commercial real estate
Allowance for loan losses
Balance at beginning of period	101	110
Provision for loan losses	103	(11)
Gross loan and lease charge-offs	1	4
Recoveries	0	6
Net loan and lease charge-offs (recoveries)	1	(2)
Balance at ending of period	171	101	110
Reserve for unfunded lending commitments
Balance at beginning of period	20	17
Provision for unfunded lending commitments	8	3
Balance at end of period	20	20	17
Total allowance for credit losses	191	121
Commercial real estate | Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses
Balance at beginning of period	(32)
Balance at ending of period		(32)
Reserve for unfunded lending commitments
Balance at beginning of period	(8)
Balance at end of period		(8)
Commercial real estate | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses
Balance at beginning of period	69
Balance at ending of period		69
Reserve for unfunded lending commitments
Balance at beginning of period	12
Balance at end of period		12
Consumer
Allowance for loan losses
Balance at beginning of period	53	54
Provision for loan losses	1	6
Gross loan and lease charge-offs	14	17
Recoveries	9	10
Net loan and lease charge-offs (recoveries)	5	7
Balance at ending of period	142	53	54
Reserve for unfunded lending commitments
Balance at beginning of period	0	0
Provision for unfunded lending commitments	2	0
Balance at end of period	8	0	$ 0
Total allowance for credit losses	150	53
Consumer | Cumulative Effect, Period of Adoption, Adjustment
Allowance for loan losses
Balance at beginning of period	93
Balance at ending of period		93
Reserve for unfunded lending commitments
Balance at beginning of period	6
Balance at end of period		6
Consumer | Cumulative Effect, Period of Adoption, Adjusted Balance
Allowance for loan losses
Balance at beginning of period	146
Balance at ending of period		146
Reserve for unfunded lending commitments
Balance at beginning of period	$ 6
Balance at end of period		$ 6

Loans, Leases, and Allowance _6

Loans, Leases, and Allowance for Credit Losses (Summary of Nonaccrual Loans) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	$ 139
Amortized cost basis with allowance	228
Total amortized cost basis	367
Related allowance	42
Accrued interest receivable written off	19
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	111
Amortized cost basis with allowance	105
Total amortized cost basis	216
Related allowance	26
Accrued interest receivable written off	16
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	73
Amortized cost basis with allowance	67
Total amortized cost basis	140
Related allowance	22
Commercial | Leasing
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	0
Total amortized cost basis	0
Related allowance	0
Commercial | Owner-occupied
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	38
Amortized cost basis with allowance	38
Total amortized cost basis	76
Related allowance	0
Commercial | Municipal
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	0
Total amortized cost basis	0
Related allowance	4
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	12
Amortized cost basis with allowance	19
Total amortized cost basis	31
Related allowance	3
Accrued interest receivable written off	2
Commercial real estate | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	0
Total amortized cost basis	0
Related allowance	0
Commercial real estate | Term
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	12
Amortized cost basis with allowance	19
Total amortized cost basis	31
Related allowance	3
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	16
Amortized cost basis with allowance	104
Total amortized cost basis	120
Related allowance	13
Accrued interest receivable written off	1
Consumer | Home equity credit line
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	2
Amortized cost basis with allowance	14
Total amortized cost basis	16
Related allowance	3
Consumer | 1-4 family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	14
Amortized cost basis with allowance	89
Total amortized cost basis	103
Related allowance	9
Consumer | Construction and other consumer real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	0
Total amortized cost basis	0
Related allowance	0
Consumer | Bankcard and other revolving plans
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	1
Total amortized cost basis	1
Related allowance	1
Consumer | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized cost basis with no allowance	0
Amortized cost basis with allowance	0
Total amortized cost basis	0
Related allowance	$ 0

Loans, Leases, and Allowance _7

Loans, Leases, and Allowance for Credit Losses (Summary of Past Due Loans (Accruing and Nonaccruing)) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	$ 53,198	$ 48,510
Past Due	278	199
Total loans	53,476	48,709
Accruing loans 90+ days past due	12	10
Nonaccrual loans that are current	367
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	30,360	25,254
Past Due	112	134
Total loans	30,472	25,388
Accruing loans 90+ days past due	2	9
Nonaccrual loans that are current	216
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	12,033	11,539
Past Due	71	16
Total loans	12,104	11,555
Accruing loans 90+ days past due	8	0
Nonaccrual loans that are current	31
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	10,805	11,717
Past Due	95	49
Total loans	10,900	11,766
Accruing loans 90+ days past due	2	1
Nonaccrual loans that are current	120
Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	13,388	14,665
Past Due	56	95
Total loans	13,444	14,760
Accruing loans 90+ days past due	2	8
Nonaccrual loans that are current	140
PPP | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	5,572
Past Due	0
Total loans	5,572	0
Accruing loans 90+ days past due	0
Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	320	334
Past Due	0	0
Total loans	320	334
Accruing loans 90+ days past due	0	1
Nonaccrual loans that are current	0
Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	8,129	7,862
Past Due	56	39
Total loans	8,185	7,901
Accruing loans 90+ days past due	0	0
Nonaccrual loans that are current	76
Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	2,951	2,393
Past Due	0	0
Total loans	2,951	2,393
Accruing loans 90+ days past due	0	0
Nonaccrual loans that are current	0
Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	2,341	2,206
Past Due	4	5
Total loans	2,345	2,211
Accruing loans 90+ days past due	4	0
Nonaccrual loans that are current	0
Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	9,692	9,333
Past Due	67	11
Total loans	9,759	9,344
Accruing loans 90+ days past due	4	0
Nonaccrual loans that are current	31
Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	2,733	2,908
Past Due	12	9
Total loans	2,745	2,917
Accruing loans 90+ days past due	0	0
Nonaccrual loans that are current	16
1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	6,891	7,532
Past Due	78	36
Total loans	6,969	7,568
Accruing loans 90+ days past due	0	0
Nonaccrual loans that are current	103
Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	630	624
Past Due	0	0
Total loans	630	624
Accruing loans 90+ days past due		0
Nonaccrual loans that are current	0
Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	428	499
Past Due	4	3
Total loans	432	502
Accruing loans 90+ days past due	2	1
Nonaccrual loans that are current	1
Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	123	154
Past Due	1	1
Total loans	124	155
Accruing loans 90+ days past due	0	0
Nonaccrual loans that are current	0
30-89 days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	140	111
30-89 days past due | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	60	77
30-89 days past due | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	57	13
30-89 days past due | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	23	21
30-89 days past due | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	26	57
30-89 days past due | PPP | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0
30-89 days past due | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
30-89 days past due | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	34	20
30-89 days past due | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
30-89 days past due | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	5
30-89 days past due | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	57	8
30-89 days past due | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	8	6
30-89 days past due | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	12	12
30-89 days past due | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
30-89 days past due | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	2	2
30-89 days past due | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	1	1
90+ days past due
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	138	88
90+ days past due | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	52	57
90+ days past due | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	14	3
90+ days past due | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	72	28
90+ days past due | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	30	38
90+ days past due | PPP | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0
90+ days past due | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
90+ days past due | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	22	19
90+ days past due | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
90+ days past due | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	4	0
90+ days past due | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	10	3
90+ days past due | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	4	3
90+ days past due | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	66	24
90+ days past due | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
90+ days past due | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	2	1
90+ days past due | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Past Due	0	0
Nonaccrual loans that are current
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	214	129
Nonaccrual loans that are current | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	158	98
Nonaccrual loans that are current | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	13	11
Nonaccrual loans that are current | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	43	20
Nonaccrual loans that are current | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	109	54
Nonaccrual loans that are current | PPP | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	0
Nonaccrual loans that are current | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	1	0
Nonaccrual loans that are current | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	48	44
Nonaccrual loans that are current | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	0	0
Nonaccrual loans that are current | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	0	1
Nonaccrual loans that are current | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	13	10
Nonaccrual loans that are current | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	9	7
Nonaccrual loans that are current | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	33	13
Nonaccrual loans that are current | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	0	0
Nonaccrual loans that are current | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	1	0
Nonaccrual loans that are current | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Nonaccrual loans that are current	$ 0	$ 0

Loans, Leases, and Allowance _8

Loans, Leases, and Allowance for Credit Losses (Summary of Outstanding Loan Balances (Accruing And Nonaccruing) Categorized By Credit Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	$ 15,931
2019	9,700
2018	7,093
2017	4,439
2016	3,104
Prior	5,596
Revolving loans amortized cost basis	7,321
Revolving loans converted to term loans amortized cost basis	292
Total loans	53,476	$ 48,709
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	11,233
2019	5,348
2018	3,934
2017	2,437
2016	1,087
Prior	2,526
Revolving loans amortized cost basis	3,766
Revolving loans converted to term loans amortized cost basis	141
Total loans	30,472	25,388
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	3,260
2019	2,992
2018	2,190
2017	876
2016	821
Prior	1,436
Revolving loans amortized cost basis	501
Revolving loans converted to term loans amortized cost basis	28
Total loans	12,104	11,555
Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,438
2019	1,360
2018	969
2017	1,126
2016	1,196
Prior	1,634
Revolving loans amortized cost basis	3,054
Revolving loans converted to term loans amortized cost basis	123
Total loans	10,900	11,766
Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	2,844
2019	3,054
2018	2,225
2017	979
2016	328
Prior	303
Revolving loans amortized cost basis	3,585
Revolving loans converted to term loans amortized cost basis	126
Total loans	13,444	14,760
PPP | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	5,572
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	5,572	0
Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	90
2019	122
2018	47
2017	36
2016	14
Prior	11
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	320	334
Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,696
2019	1,345
2018	1,303
2017	1,003
2016	677
Prior	1,968
Revolving loans amortized cost basis	178
Revolving loans converted to term loans amortized cost basis	15
Total loans	8,185	7,901
Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,031
2019	827
2018	359
2017	419
2016	68
Prior	244
Revolving loans amortized cost basis	3
Revolving loans converted to term loans amortized cost basis	0
Total loans	2,951	2,393
Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	582
2019	1,006
2018	278
2017	41
2016	1
Prior	6
Revolving loans amortized cost basis	428
Revolving loans converted to term loans amortized cost basis	3
Total loans	2,345	2,211
Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	2,678
2019	1,986
2018	1,912
2017	835
2016	820
Prior	1,430
Revolving loans amortized cost basis	73
Revolving loans converted to term loans amortized cost basis	25
Total loans	9,759	9,344
Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	2,625
Revolving loans converted to term loans amortized cost basis	120
Total loans	2,745	2,917
1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,187
2019	1,029
2018	841
2017	1,100
2016	1,191
Prior	1,621
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	6,969	7,568
Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	200
2019	296
2018	106
2017	16
2016	1
Prior	11
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	630	624
Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	429
Revolving loans converted to term loans amortized cost basis	3
Total loans	432	502
Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	51
2019	35
2018	22
2017	10
2016	4
Prior	2
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	124	$ 155
Pass | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	2,585
2019	2,743
2018	1,903
2017	829
2016	296
Prior	228
Revolving loans amortized cost basis	3,298
Revolving loans converted to term loans amortized cost basis	109
Total loans	11,991
Pass | PPP | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	5,572
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	5,572
Pass | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	87
2019	121
2018	44
2017	34
2016	14
Prior	5
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	305
Pass | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,588
2019	1,205
2018	1,167
2017	895
2016	585
Prior	1,806
Revolving loans amortized cost basis	161
Revolving loans converted to term loans amortized cost basis	11
Total loans	7,418
Pass | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,031
2019	827
2018	359
2017	419
2016	68
Prior	227
Revolving loans amortized cost basis	3
Revolving loans converted to term loans amortized cost basis	0
Total loans	2,934
Pass | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	558
2019	933
2018	267
2017	41
2016	1
Prior	6
Revolving loans amortized cost basis	423
Revolving loans converted to term loans amortized cost basis	3
Total loans	2,232
Pass | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	2,524
2019	1,858
2018	1,639
2017	761
2016	778
Prior	1,291
Revolving loans amortized cost basis	73
Revolving loans converted to term loans amortized cost basis	20
Total loans	8,944
Pass | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	2,606
Revolving loans converted to term loans amortized cost basis	115
Total loans	2,721
Pass | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1,185
2019	1,017
2018	833
2017	1,081
2016	1,174
Prior	1,570
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	6,860
Pass | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	200
2019	296
2018	106
2017	16
2016	1
Prior	11
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	630
Pass | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	426
Revolving loans converted to term loans amortized cost basis	2
Total loans	428
Pass | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	51
2019	35
2018	22
2017	10
2016	4
Prior	2
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	124
Special Mention | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	79
2019	152
2018	183
2017	98
2016	4
Prior	43
Revolving loans amortized cost basis	110
Revolving loans converted to term loans amortized cost basis	1
Total loans	670
Special Mention | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	1
2019	0
2018	2
2017	1
2016	0
Prior	6
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	10
Special Mention | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	72
2019	65
2018	60
2017	60
2016	51
Prior	41
Revolving loans amortized cost basis	9
Revolving loans converted to term loans amortized cost basis	3
Total loans	361
Special Mention | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	8
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	8
Special Mention | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	24
2019	43
2018	11
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	5
Revolving loans converted to term loans amortized cost basis	0
Total loans	83
Special Mention | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	110
2019	89
2018	177
2017	42
2016	23
Prior	85
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	5
Total loans	531
Special Mention | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	2
Revolving loans converted to term loans amortized cost basis	0
Total loans	2
Special Mention | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	2
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	2
Special Mention | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Special Mention | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Special Mention | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Accruing Substandard | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	123
2019	157
2018	129
2017	44
2016	26
Prior	17
Revolving loans amortized cost basis	141
Revolving loans converted to term loans amortized cost basis	6
Total loans	643
Accruing Substandard | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	2
2019	1
2018	1
2017	1
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	5
Accruing Substandard | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	28
2019	64
2018	61
2017	37
2016	35
Prior	98
Revolving loans amortized cost basis	6
Revolving loans converted to term loans amortized cost basis	1
Total loans	330
Accruing Substandard | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	9
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	9
Accruing Substandard | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	30
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	30
Accruing Substandard | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	41
2019	34
2018	96
2017	30
2016	18
Prior	34
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	253
Accruing Substandard | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	6
Revolving loans converted to term loans amortized cost basis	0
Total loans	6
Accruing Substandard | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	1
2017	0
2016	2
Prior	1
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	4
Accruing Substandard | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Accruing Substandard | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	3
Revolving loans converted to term loans amortized cost basis	0
Total loans	3
Accruing Substandard | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Nonaccrual | Commercial and industrial | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	57
2019	2
2018	10
2017	8
2016	2
Prior	15
Revolving loans amortized cost basis	36
Revolving loans converted to term loans amortized cost basis	10
Total loans	140
Nonaccrual | Leasing | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Nonaccrual | Owner-occupied | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	8
2019	11
2018	15
2017	11
2016	6
Prior	23
Revolving loans amortized cost basis	2
Revolving loans converted to term loans amortized cost basis	0
Total loans	76
Nonaccrual | Municipal | Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Nonaccrual | Construction and land development | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Nonaccrual | Term | Commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	3
2019	5
2018	0
2017	2
2016	1
Prior	20
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	31
Nonaccrual | Home equity credit line | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	11
Revolving loans converted to term loans amortized cost basis	5
Total loans	16
Nonaccrual | 1-4 family residential | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	2
2019	12
2018	7
2017	19
2016	15
Prior	48
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	103
Nonaccrual | Construction and other consumer real estate | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	0
Nonaccrual | Bankcard and other revolving plans | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	1
Total loans	1
Nonaccrual | Other | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
2020	0
2019	0
2018	0
2017	0
2016	0
Prior	0
Revolving loans amortized cost basis	0
Revolving loans converted to term loans amortized cost basis	0
Total loans	$ 0

Loans, Leases, and Allowance _9

Loans, Leases, and Allowance for Credit Losses (Summary of Selected Information on TDRs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	$ 311	$ 153
Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	18	13
Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	11
Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	12	14
Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	39	21
Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	116	22
Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	122	72
Accruing
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	198	78
Accruing | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	7
Accruing | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	7
Accruing | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	11
Accruing | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	20	1
Accruing | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	103	13
Accruing | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	52	39
Accruing | Commercial
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	29	31
Accruing | Commercial | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	5	4
Accruing | Commercial | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	3
Accruing | Commercial | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	0
Accruing | Commercial | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	7	12
Accruing | Commercial | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	12	12
Accruing | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	7	16
Accruing | Commercial | Commercial and industrial | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Accruing | Commercial | Commercial and industrial | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	2
Accruing | Commercial | Commercial and industrial | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial | Commercial and industrial | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial | Commercial and industrial | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	8
Accruing | Commercial | Commercial and industrial | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	5
Accruing | Commercial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	22	15
Accruing | Commercial | Owner-occupied | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	5	3
Accruing | Commercial | Owner-occupied | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	1
Accruing | Commercial | Owner-occupied | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial | Owner-occupied | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	0
Accruing | Commercial | Owner-occupied | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	4
Accruing | Commercial | Owner-occupied | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	8	7
Accruing | Commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	134	6
Accruing | Commercial real estate | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	2
Accruing | Commercial real estate | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	16	1
Accruing | Commercial real estate | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	94	0
Accruing | Commercial real estate | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	23	3
Accruing | Commercial real estate | Construction and land development
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Construction and land development | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Construction and land development | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Construction and land development | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Construction and land development | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Construction and land development | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Construction and land development | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Term
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	134	6
Accruing | Commercial real estate | Term | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	2
Accruing | Commercial real estate | Term | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Term | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Commercial real estate | Term | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	16	1
Accruing | Commercial real estate | Term | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	94	0
Accruing | Commercial real estate | Term | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	23	3
Accruing | Consumer
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	35	41
Accruing | Consumer | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	1
Accruing | Consumer | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	4
Accruing | Consumer | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	11
Accruing | Consumer | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	1
Accruing | Consumer | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	17	24
Accruing | Consumer | Home equity credit line
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	11
Accruing | Consumer | Home equity credit line | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Home equity credit line | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	2
Accruing | Consumer | Home equity credit line | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	7	7
Accruing | Consumer | Home equity credit line | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Home equity credit line | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Home equity credit line | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	2
Accruing | Consumer | 1-4 family residential
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	25	29
Accruing | Consumer | 1-4 family residential | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	4	1
Accruing | Consumer | 1-4 family residential | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	1
Accruing | Consumer | 1-4 family residential | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	4
Accruing | Consumer | 1-4 family residential | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | 1-4 family residential | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	1
Accruing | Consumer | 1-4 family residential | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	15	22
Accruing | Consumer | Construction and other consumer real estate
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Accruing | Consumer | Construction and other consumer real estate | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Construction and other consumer real estate | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Accruing | Consumer | Construction and other consumer real estate | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Construction and other consumer real estate | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Construction and other consumer real estate | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Accruing | Consumer | Construction and other consumer real estate | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	113	75
Nonaccruing | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	8	6
Nonaccruing | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	4
Nonaccruing | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	3
Nonaccruing | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	19	20
Nonaccruing | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	13	9
Nonaccruing | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	70	33
Nonaccruing | Commercial
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	83	60
Nonaccruing | Commercial | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	5	5
Nonaccruing | Commercial | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	4
Nonaccruing | Commercial | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	6	20
Nonaccruing | Commercial | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	5
Nonaccruing | Commercial | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	62	26
Nonaccruing | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	65	50
Nonaccruing | Commercial | Commercial and industrial | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Commercial and industrial | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	4
Nonaccruing | Commercial | Commercial and industrial | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Commercial and industrial | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	20
Nonaccruing | Commercial | Commercial and industrial | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	4
Nonaccruing | Commercial | Commercial and industrial | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	52	22
Nonaccruing | Commercial | Owner-occupied
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	18	10
Nonaccruing | Commercial | Owner-occupied | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	5	5
Nonaccruing | Commercial | Owner-occupied | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Owner-occupied | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Owner-occupied | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	0
Nonaccruing | Commercial | Owner-occupied | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Nonaccruing | Commercial | Owner-occupied | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	4
Nonaccruing | Commercial | Municipal
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Municipal | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Municipal | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Municipal | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Municipal | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Municipal | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial | Municipal | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	20	7
Nonaccruing | Commercial real estate | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	1
Nonaccruing | Commercial real estate | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	13	0
Nonaccruing | Commercial real estate | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	3
Nonaccruing | Commercial real estate | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	3
Nonaccruing | Commercial real estate | Construction and land development
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Construction and land development | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Construction and land development | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Construction and land development | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Construction and land development | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Construction and land development | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Construction and land development | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Term
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	20	7
Nonaccruing | Commercial real estate | Term | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	1
Nonaccruing | Commercial real estate | Term | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Term | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Commercial real estate | Term | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	13	0
Nonaccruing | Commercial real estate | Term | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	3	3
Nonaccruing | Commercial real estate | Term | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	3
Nonaccruing | Consumer
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	10	8
Nonaccruing | Consumer | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	0
Nonaccruing | Consumer | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	0
Nonaccruing | Consumer | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	3
Nonaccruing | Consumer | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Nonaccruing | Consumer | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	6	4
Nonaccruing | Consumer | Home equity credit line
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	2
Nonaccruing | Consumer | Home equity credit line | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Home equity credit line | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Home equity credit line | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	2	2
Nonaccruing | Consumer | Home equity credit line | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Home equity credit line | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Home equity credit line | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | 1-4 family residential
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	8	6
Nonaccruing | Consumer | 1-4 family residential | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	0
Nonaccruing | Consumer | 1-4 family residential | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	1	0
Nonaccruing | Consumer | 1-4 family residential | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Nonaccruing | Consumer | 1-4 family residential | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | 1-4 family residential | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	1
Nonaccruing | Consumer | 1-4 family residential | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	6	4
Nonaccruing | Consumer | Construction and other consumer real estate
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Construction and other consumer real estate | Interest rate below market
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Construction and other consumer real estate | Maturity or term extension
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Construction and other consumer real estate | Principal forgiveness
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Construction and other consumer real estate | Payment deferral
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Construction and other consumer real estate | Other
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	0	0
Nonaccruing | Consumer | Construction and other consumer real estate | Multiple modification types
Financing Receivable, Modifications [Line Items]
Recorded investment resulting from the following modification types	$ 0	$ 0

Loans, Leases, and Allowance_10

Loans, Leases, and Allowance for Credit Losses (Schedule of Investment of Accruing and Nonaccruing Loans Modified as Troubled Debt Restructurings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	$ 3	$ 1
Loans modified as troubled debt restructurings loans	228	40
Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	2	1
Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	1	0
Accruing
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	0
Accruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	0
Accruing | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	0
Nonaccruing
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	3	1
Nonaccruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	2	1
Nonaccruing | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	1	0
Commercial and industrial | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	2	0
Commercial and industrial | Accruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	0
Commercial and industrial | Nonaccruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	2	0
Owner-occupied | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	1
Owner-occupied | Accruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	0
Owner-occupied | Nonaccruing | Commercial
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	1
1-4 family residential | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	1	0
1-4 family residential | Accruing | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	0	0
1-4 family residential | Nonaccruing | Consumer
Financing Receivable, Modifications [Line Items]
Financing receivable, modifications, subsequent default, recorded investment	$ 1	$ 0

Loans, Leases, and Allowance_11

Loans, Leases, and Allowance for Credit Losses (Collateral-Dependent Loans) (Details) $ in Millions	Dec. 31, 2020USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 47
Commercial and industrial | Commercial | Single family residential, Agriculture
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 20
Weighted Average LTV	55.00%
Owner-occupied | Commercial | Office Building
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 10
Weighted Average LTV	47.00%
Term | Commercial real estate | Multi-family, Hotel/Motel, Retail
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 12
Weighted Average LTV	58.00%
Home equity credit line | Consumer | Single family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 3
Weighted Average LTV	34.00%
1-4 family residential | Consumer | Single family residential
Financing Receivable, Allowance for Credit Losses [Line Items]
Amortized Cost	$ 2
Weighted Average LTV	60.00%

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)derivativederivative_instrument	Dec. 31, 2019USD ($)	Mar. 31, 2020USD ($)derivative_instrument
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	$ 17,877,000,000	$ 15,030,000,000
Terminated swaps			$ 1,000,000,000
Number of derivatives terminated	2		2
Terminated swaps, amortization of debt basis adjustment	$ 3,000,000
Terminated swaps, unamortized debt basis adjustments	12,000,000
Redesignated swaps, unamortized basis adjustments	7,000,000
Derivative liability, fair value	38,000,000	19,000,000
Cash collateral pledged for derivative liabilities	103,000,000
Additional collateral that would be required to be pledge if credit rating was downgraded by one notch	2,000,000
Interest Rate Swap, Terminated One
Derivative Instruments, Gain (Loss) [Line Items]
Terminated swaps, maturity value			$ 500,000,000
Interest Rate Swap, Terminated Two
Derivative Instruments, Gain (Loss) [Line Items]
Terminated swaps, maturity value			$ 500,000,000
Other liabilities
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability, fair value	418,000,000	167,000,000
Derivatives designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	4,033,000,000	5,088,000,000
Deferred gains in OCI	101,000,000	47,000,000
Derivatives designated as hedges | Other liabilities
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability, fair value	$ 0	0
Fair Value Hedging | Derivatives designated as hedges | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate derivatives remaining | derivative_instrument	1
Derivative, notional amount	$ 500,000,000	1,500,000,000
Fair Value Hedging | Derivatives designated as hedges | Asset hedges: Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	383,000,000	0
Deferred gains in OCI	0	0
Fair Value Hedging | Derivatives designated as hedges | Other liabilities | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability, fair value	0	0
Fair Value Hedging | Derivatives designated as hedges | Other liabilities | Asset hedges: Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability, fair value	0	0
Cash Flow Hedging | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Deferred gains in OCI	95,000,000
Cash Flow Hedging | Derivatives designated as hedges | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, notional amount	3,150,000,000	3,588,000,000
Deferred gains in OCI	101,000,000	47,000,000
Cash Flow Hedging | Derivatives designated as hedges | Other liabilities | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative liability, fair value	$ 0	$ 0

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities (Notional and Recorded Fair Values) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative, Notional amount	$ 17,877,000,000	$ 15,030,000,000
Derivative asset, fair value	418,000,000	153,000,000
Derivative liability, fair value	38,000,000	19,000,000
Net credit valuation adjustment reducing fair value	18,000,000	11,000,000
Other assets
Derivative [Line Items]
Derivative asset, fair value	420,000,000	158,000,000
Other liabilities
Derivative [Line Items]
Derivative liability, fair value	418,000,000	167,000,000
Derivatives designated as hedging instruments
Derivative [Line Items]
Derivative, Notional amount	4,033,000,000	5,088,000,000
Derivatives designated as hedging instruments | Other assets
Derivative [Line Items]
Derivative asset, fair value	3,000,000	0
Derivatives designated as hedging instruments | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Purchased interest rate floors | Cash Flow Hedging
Derivative [Line Items]
Derivative, Notional amount	0	0
Derivatives designated as hedging instruments | Purchased interest rate floors | Other assets | Cash Flow Hedging
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivatives designated as hedging instruments | Purchased interest rate floors | Other liabilities | Cash Flow Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Cash Flow Hedging
Derivative [Line Items]
Derivative, Notional amount	3,150,000,000	3,588,000,000
Derivatives designated as hedging instruments | Interest rate swaps | Fair Value Hedging
Derivative [Line Items]
Derivative, Notional amount	500,000,000	1,500,000,000
Derivatives designated as hedging instruments | Interest rate swaps | Other assets | Cash Flow Hedging
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Other liabilities | Cash Flow Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Interest rate swaps | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives designated as hedging instruments | Asset hedges: Pay-fixed interest rate swaps | Fair Value Hedging
Derivative [Line Items]
Derivative, Notional amount	383,000,000	0
Derivatives designated as hedging instruments | Asset hedges: Pay-fixed interest rate swaps | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	3,000,000	0
Derivatives designated as hedging instruments | Asset hedges: Pay-fixed interest rate swaps | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	0	0
Derivatives not designated as hedging instruments
Derivative [Line Items]
Derivative, Notional amount	13,844,000,000	9,942,000,000
Derivatives not designated as hedging instruments | Other assets
Derivative [Line Items]
Derivative asset, fair value	417,000,000	158,000,000
Derivatives not designated as hedging instruments | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	418,000,000	167,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives
Derivative [Line Items]
Derivative, Notional amount	5,986,000,000	4,409,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	390,000,000	146,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	390,000,000	146,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	2,000,000	5,000,000
Derivatives not designated as hedging instruments | Customer-facing interest rate derivatives | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	2,000,000	5,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives
Derivative [Line Items]
Derivative, Notional amount	5,986,000,000	4,422,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	3,000,000	5,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other assets | Fair Value Hedging
Derivative [Line Items]
Derivative asset, fair value	1,000,000	0
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	409,000,000	157,000,000
Derivatives not designated as hedging instruments | Offsetting interest rate derivatives | Other liabilities | Fair Value Hedging
Derivative [Line Items]
Derivative liability, fair value	29,000,000	9,000,000
Derivatives not designated as hedging instruments | Other interest rate derivatives
Derivative [Line Items]
Derivative, Notional amount	1,649,000,000	726,000,000
Derivatives not designated as hedging instruments | Other interest rate derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	20,000,000	3,000,000
Derivatives not designated as hedging instruments | Other interest rate derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	3,000,000	1,000,000
Derivatives not designated as hedging instruments | Foreign exchange derivatives
Derivative [Line Items]
Derivative, Notional amount	223,000,000	385,000,000
Derivatives not designated as hedging instruments | Foreign exchange derivatives | Other assets
Derivative [Line Items]
Derivative asset, fair value	4,000,000	4,000,000
Derivatives not designated as hedging instruments | Foreign exchange derivatives | Other liabilities
Derivative [Line Items]
Derivative liability, fair value	$ 4,000,000	$ 4,000,000

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities (Derivative gain (loss) recognized/reclassified) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain/(loss) reclassified from AOCI into income	$ 36	$ (5)	$ (3)
Gains to be reclassified within the next 12 months into interest income	61
Cash Flow Hedging | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	95
Derivatives designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	101	47
Excluded components deferred in AOCI (amortization approach)	0	27
Amount of gain/(loss) reclassified from AOCI into income	47	(4)
Interest on fair value hedges	18	3
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges | Cash Flow Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Terminated or redesignated, unamortized basis adjustments	7
Derivatives designated as hedges | Cash Flow Hedging | Purchased interest rate floors
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Excluded components deferred in AOCI (amortization approach)	0	27
Amount of gain/(loss) reclassified from AOCI into income	11	3
Interest on fair value hedges	0	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges | Cash Flow Hedging | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	101	47
Excluded components deferred in AOCI (amortization approach)	0	0
Amount of gain/(loss) reclassified from AOCI into income	36	(7)
Interest on fair value hedges	0	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges | Fair Value Hedging
Derivative Instruments, Gain (Loss) [Line Items]
Terminated or redesignated, unamortized basis adjustments	12
Derivatives designated as hedges | Fair Value Hedging | Receive-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Excluded components deferred in AOCI (amortization approach)	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Interest on fair value hedges	6	3
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges | Fair Value Hedging | Basis amortization on terminated hedges, liability hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Excluded components deferred in AOCI (amortization approach)	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Interest on fair value hedges	13	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges | Fair Value Hedging | Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Excluded components deferred in AOCI (amortization approach)	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Interest on fair value hedges	(1)	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	0	0
Derivatives designated as hedges | Fair Value Hedging | Basis amortization on terminated hedges, asset hedges
Derivative Instruments, Gain (Loss) [Line Items]
Effective portion of derivative gain/(loss) deferred in AOCI	0	0
Excluded components deferred in AOCI (amortization approach)	0	0
Amount of gain/(loss) reclassified from AOCI into income	0	0
Interest on fair value hedges	0	0
Hedge ineffectiveness / AOCI reclass due to missed forecast	$ 0	$ 0

Derivative Instruments and He_6

Derivative Instruments and Hedging Activities (Derivatives Not Designated As Hedges) (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Noninterest (Other) Income/(Expense)	$ 53	$ 40
Customer-facing interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Noninterest (Other) Income/(Expense)	324	146
Offsetting interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Noninterest (Other) Income/(Expense)	(300)	(129)
Other interest rate derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Noninterest (Other) Income/(Expense)	8	0
Foreign exchange derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Noninterest (Other) Income/(Expense)	$ 21	$ 23

Derivative Instruments and He_7

Derivative Instruments and Hedging Activities (Gain (loss) recorded in income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Total income statement impact	$ (6)	$ (9)	$ (1)
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) in fair value of derivative	63	5
Increase (decrease) in fair value of hedged item	(63)	(5)
Total income statement impact	0	0
Asset hedges: Pay-fixed interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) in fair value of derivative	28	0
Increase (decrease) in fair value of hedged item	(28)	0
Total income statement impact	$ 0	$ 0

Derivative Instruments and He_8

Derivative Instruments and Hedging Activities (Long-term debt hedged items) (Details) - Fair Value Hedging - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Par value of hedged liabilities	$ (500,000,000)	$ (1,500,000,000)
Carrying amount of hedged liabilities	(537,000,000)	(1,510,000,000)
Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged liabilities	(37,000,000)	(10,000,000)
Par value of hedged assets	383,000,000	0
Carrying amount of hedged assets	362,000,000	0
Cumulative amount of fair value hedging adjustment included in the carrying amount of the hedged assets	$ (21,000,000)	$ 0

Leases (Narrative) (Details)

Leases (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)branch	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Finance Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebt	us-gaap:LongTermDebt
Number of branches | branch	422
Number of branches owned | branch	273
Number of branches leased | branch	149
Operating lease right-of-use assets	$ 213	$ 218
Finance lease right-of-use assets	4
Operating lease income	12
Sales-type or direct financing leases	320	334
Sales-type or direct financing leases income	$ 13	$ 14

Leases (Assets and Liabilities)

Leases (Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating right-of-use assets, net of amortization	$ 213	$ 218
Operating lease liabilities	$ 240	$ 246
Weighted average remaining lease term, operating leases	8 years 10 months 24 days	9 years 1 month 6 days
Weighted average remaining lease term, finance leases	19 years 2 months 12 days	20 years 2 months 12 days
Weighted average discount rate, operating leases	2.90%	3.20%
Weighted average discount rate, finance leases	3.10%	3.10%

Leases (Components of Lease Exp

Leases (Components of Lease Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease costs	$ 49	$ 48
Variable lease costs	49	53
Total lease cost	$ 98	$ 101

Leases (Supplemental Cash Flow

Leases (Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating cash disbursements from operating leases	$ 51	$ 50
New operating lease liabilities	9	10
New finance lease liabilities	0	6
Total	$ 9	$ 16

Leases (Maturities Analysis) (D

Leases (Maturities Analysis) (Details) $ in Millions	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 49
2022	46
2023	39
2024	30
2025	21
Thereafter	95
Total	$ 280

Premises, Equipment and Softw_3

Premises, Equipment and Software, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Land	$ 257	$ 235
Buildings	802	747
Furniture and equipment	420	442
Leasehold improvements	165	164
Software	581	507
Total	2,225	2,095
Less accumulated depreciation and amortization	1,016	953
Net book value	1,209	1,142
Capitalized costs	$ 213	$ 105

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Schedule of Intangible Assets and Related Accumulated Amortization) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 197	$ 195
Accumulated amortization	(195)	(195)
Net carrying amount	2	0
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	167	167
Accumulated amortization	(167)	(167)
Net carrying amount	0	0
Customer relationships and other intangibles
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	30	28
Accumulated amortization	(28)	(28)
Net carrying amount	$ 2	$ 0

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Schedule Of Goodwill) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill, Beginning balance	$ 1,014,000,000	$ 1,014,000,000
Impairment losses	0	0
Goodwill, Ending balance	1,014,000,000	1,014,000,000
Zions Bank | Operating Segments
Goodwill [Line Items]
Goodwill, Beginning balance	20,000,000	20,000,000
Impairment losses	0	0
Goodwill, Ending balance	20,000,000	20,000,000
CB&T | Operating Segments
Goodwill [Line Items]
Goodwill, Beginning balance	379,000,000	379,000,000
Impairment losses	0	0
Goodwill, Ending balance	379,000,000	379,000,000
Amegy | Operating Segments
Goodwill [Line Items]
Goodwill, Beginning balance	615,000,000	615,000,000
Impairment losses	0	0
Goodwill, Ending balance	$ 615,000,000	$ 615,000,000

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill impairment loss	$ 0	$ 0

Deposits (Scheduled Maturities

Deposits (Scheduled Maturities Of All Time Deposits) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
2021	$ 2,239
2022	189
2023	78
2024	42
2025	39
Thereafter	1
Total	$ 2,588	$ 4,719

Deposits (Schedule of Contractu

Deposits (Schedule of Contractual Maturities of Time Deposits With a Denomination of $100,000 and Over) (Details) $ in Millions	Dec. 31, 2020USD ($)
Deposits [Abstract]
Three months or less	$ 274
After three months through six months	204
After six months through twelve months	405
After twelve months	166
Total	$ 1,049

Deposits (Narrative) (Details)

Deposits (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deposits [Abstract]
Time deposits, $250,000 or more	$ 554	$ 885
Time deposits, less than $250,000	2,000	1,600
Deposit overdrafts reclassified as loan balances	$ 9	$ 10

Short-Term Borrowings (Summary

Short-Term Borrowings (Summary of Short-Term Borrowings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Year-end balance	$ 1,572	$ 2,053	$ 5,653
Securities sold, not yet purchased	61	66	85
Federal funds purchased and other short-term borrowings	1,572	2,053	5,653
Federal Home Loan Bank advances
Short-term Debt [Line Items]
Average amount outstanding	$ 206	$ 3,149	$ 2,971
Average rate	1.11%	2.50%	2.01%
Highest month-end balance	$ 2,200	$ 4,950	$ 5,400
Year-end balance	$ 0	$ 1,000	$ 4,500
Average rate on outstanding advances at year-end	0.00%	1.73%	2.61%
Federal funds purchased and other short-term borrowings	$ 0	$ 1,000	$ 4,500
Federal funds purchased
Short-term Debt [Line Items]
Other short-term borrowings, year-end balances	1,105	472	541
Security repurchase agreements
Short-term Debt [Line Items]
Other short-term borrowings, year-end balances	$ 406	$ 515	$ 527

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Short-term Debt [Line Items]
Percentage of outstanding advance for unencumbered collateral	100.00%
Amount available for FHLB advances	$ 13,300
Amount available for Federal Reserve borrowings	1,572	$ 2,053	$ 5,653
Secured debt, repurchase agreements overnight	392
Secured debt, repurchase agreements term	14
Federal Reserve Bank Advances
Short-term Debt [Line Items]
Amount available for Federal Reserve borrowings	$ 3,800
Federal Funds Purchased and Securities Sold under Agreements to Repurchase
Short-term Debt [Line Items]
Maturity period (in days)	30 days
Security repurchase agreements | Minimum
Short-term Debt [Line Items]
Maturity period (in days)	30 days
Security repurchase agreements | Maximum
Short-term Debt [Line Items]
Maturity period (in days)	60 days

Long-Term Debt (Schedule of Lon

Long-Term Debt (Schedule of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Long-term Debt, Unclassified [Abstract]
Subordinated notes	$ 619	$ 572
Senior notes	713	1,147
Finance lease obligations	4	4
Total	$ 1,336	$ 1,723

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020USD ($)derivative	Mar. 31, 2020derivative_instrument
Debt Instrument [Line Items]
Number of derivatives terminated	2	2
Senior Notes, Interest Rate 3.50% | Senior Notes
Debt Instrument [Line Items]
Repayments of debt	$ 219,000,000
Debt interest rate	3.50%
Senior Notes, Interest Rate 3.35% | Senior Notes
Debt Instrument [Line Items]
Repayments of debt	$ 210,000,000
Debt interest rate	3.35%
Subordinated Notes, Interest Rate 3.25% | Subordinated Debt
Debt Instrument [Line Items]
Debt interest rate	3.25%
Face amount of debt	$ 500,000,000
Subordinated Notes, Interest Rate 6.95%
Debt Instrument [Line Items]
New interest rate	3mL+3.89%
Subordinated Notes, Interest Rate 6.95% | Subordinated Debt
Debt Instrument [Line Items]
Debt interest rate	6.95%

Long-Term Debt (Schedule of Sub

Long-Term Debt (Schedule of Subordinated Notes) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Subordinated Borrowing [Line Items]
Subordinated notes	$ 619	$ 572
Subordinated notes, Par amount	588
Subordinated Notes, Interest Rate 6.95%
Subordinated Borrowing [Line Items]
Subordinated notes	87
Subordinated notes, Par amount	$ 88
Subordinated Notes, Interest Rate 6.95% | Subordinated Debt
Subordinated Borrowing [Line Items]
Coupon rate	6.95%
Subordinated Notes, Interest Rate 3.25%
Subordinated Borrowing [Line Items]
Subordinated notes	$ 532
Subordinated notes, Par amount	$ 500
Subordinated Notes, Interest Rate 3.25% | Subordinated Debt
Subordinated Borrowing [Line Items]
Coupon rate	3.25%

Long-Term Debt (Schedule of Sen

Long-Term Debt (Schedule of Senior Notes) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Senior notes	$ 713	$ 1,147
Senior notes, Par amount	703
Senior Notes, Interest Rate 4.50%
Debt Instrument [Line Items]
Senior notes	132
Senior notes, Par amount	$ 132
Senior Notes, Interest Rate 4.50% | Senior Notes
Debt Instrument [Line Items]
Coupon rate	4.50%
Senior Notes, Interest Rate 3.50%
Debt Instrument [Line Items]
Senior notes	$ 285
Senior notes, Par amount	$ 281
Senior Notes, Interest Rate 3.50% | Senior Notes
Debt Instrument [Line Items]
Coupon rate	3.50%
Senior Notes, Interest Rate 3.35%
Debt Instrument [Line Items]
Senior notes	$ 296
Senior notes, Par amount	$ 290
Senior Notes, Interest Rate 3.35% | Senior Notes
Debt Instrument [Line Items]
Coupon rate	3.35%

Long-Term Debt (Schedule of Mat

Long-Term Debt (Schedule of Maturities on Long-Term Debt) (Details) $ in Millions	Dec. 31, 2020USD ($)
Long-term Debt, Unclassified [Abstract]
2021	$ 282
2022	289
2023	132
2024	0
2025	0
Thereafter	585
Total	$ 1,288

Shareholders' Equity (Narrative

Shareholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	May 22, 2020	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Preferred stock, authorized shares (in shares)		4,400,000	4,400,000
Liquidation preference of preferred stock (per share)		$ 1,000
Preferred stock, liquidation preference per depositary share (in dollars per share)		$ 25
Depositary share, preferred stock ownership interest		0.025%
Shares outstanding (in shares)		164,100,000
Common stock, par value (in dollars per share)		$ 0.001	$ 0.001
Common stock and additional paid-in capital		$ 2,700
Common stock and additional paid-in capital decrease		$ 49
Common stock and additional paid-in capital decrease (as a percent)		2.00%
Common stock repurchased (in shares)		1,700,000	23,500,000
Fair value of stock repurchased		$ 75	$ 1,100
Average price per share of stock repurchased (in dollars per share)		$ 45.02	$ 46.80
Accumulated other comprehensive income		$ 325	$ 43
Common stock held in trust		13	13
Total invested assets of trusts		120	113
Total obligations of trusts		$ 133	$ 126
Warrant
Schedule of Equity Method Investments [Line Items]
Warrants expired unexercised (in shares)	29,200,000
Warrant exercise price (in dollars per share)	$ 33.31
Common stock, conversion (in shares)	1.10

Shareholders' Equity (Preferred

Shareholders' Equity (Preferred Stock) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Carrying value, Preferred stock	$ 566	$ 566
Preferred stock, Authorized (in shares)	4,400,000	4,400,000
Parent | Series A
Schedule of Equity Method Investments [Line Items]
Carrying value, Preferred stock	$ 67	$ 67
Preferred stock, Authorized (in shares)	140,000,000
Preferred stock, Outstanding (in shares)	66,139,000
Rate	> of 4.0% or 3mL+0.52%
Earliest redemption date	Dec. 15, 2011
Parent | Series G
Schedule of Equity Method Investments [Line Items]
Carrying value, Preferred stock	$ 138	138
Preferred stock, Authorized (in shares)	200,000,000
Preferred stock, Outstanding (in shares)	138,391,000
Preferred Stock, Dividend Rate, Percentage	6.30%
Earliest redemption date	Mar. 15, 2023
Parent | Series H
Schedule of Equity Method Investments [Line Items]
Carrying value, Preferred stock	$ 126	126
Preferred stock, Authorized (in shares)	126,221,000
Preferred stock, Outstanding (in shares)	126,221,000
Preferred Stock, Dividend Rate, Percentage	5.75%
Earliest redemption date	Jun. 15, 2019
Parent | Series I
Schedule of Equity Method Investments [Line Items]
Carrying value, Preferred stock	$ 99	99
Preferred stock, Authorized (in shares)	300,893,000
Preferred stock, Outstanding (in shares)	98,555,000
Preferred Stock, Dividend Rate, Percentage	5.80%
Earliest redemption date	Jun. 15, 2023
Parent | Series J
Schedule of Equity Method Investments [Line Items]
Carrying value, Preferred stock	$ 136	$ 136
Preferred stock, Authorized (in shares)	195,152,000
Preferred stock, Outstanding (in shares)	136,368,000
Preferred Stock, Dividend Rate, Percentage	7.20%
Earliest redemption date	Sep. 15, 2023

Shareholders' Equity (Summary O

Shareholders' Equity (Summary Of Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 7,353	$ 7,578	$ 7,679
Other comprehensive income (loss) before reclassifications, net of tax	297	287
Amounts reclassified from AOCI, net of tax	(15)	6
Other comprehensive income (loss)	282	293	(111)
Ending balance	7,886	7,353	7,578
Income tax expense included in other comprehensive income	91	96
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	43	(250)	(139)
Ending balance	325	43	(250)
Net unrealized gains (losses) on investment securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	29	(228)
Other comprehensive income (loss) before reclassifications, net of tax	229	257
Amounts reclassified from AOCI, net of tax	0	0
Other comprehensive income (loss)	229	257
Ending balance	258	29	(228)
Income tax expense included in other comprehensive income	74	84
Net unrealized gains (losses) on derivatives and other
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	28	(1)
Other comprehensive income (loss) before reclassifications, net of tax	77	24
Amounts reclassified from AOCI, net of tax	(36)	5
Other comprehensive income (loss)	41	29
Ending balance	69	28	(1)
Income tax expense included in other comprehensive income	13	10
Pension and post-retirement
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(14)	(21)
Other comprehensive income (loss) before reclassifications, net of tax	(9)	6
Amounts reclassified from AOCI, net of tax	21	1
Other comprehensive income (loss)	12	7
Ending balance	(2)	(14)	$ (21)
Income tax expense included in other comprehensive income	$ 4	$ 2

Shareholders' Equity (Amounts R

Shareholders' Equity (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated other comprehensive income [Line Items]
Interest and fees on loans									$ 2,050	$ 2,289	$ 2,102
Income tax expense (benefit)									(133)	(237)	(259)
Net income	$ 284	$ 175	$ 66	$ 14	$ 183	$ 222	$ 198	$ 213	539	816	884
Other noninterest expense									(241)	(225)	(197)
Net unrealized gains (losses) on derivative instruments | Amounts reclassified from AOCI
Accumulated other comprehensive income [Line Items]
Interest and fees on loans									47	(4)	(4)
Income tax expense (benefit)									11	(1)	(1)
Net income									36	(3)	(3)
Amortization of net actuarial loss | Amounts reclassified from AOCI
Accumulated other comprehensive income [Line Items]
Income tax expense (benefit)									(7)	(1)	(1)
Net income									(21)	(1)	(2)
Other noninterest expense									$ (28)	$ (2)	$ (3)

Regulatory Matters (Summary of

Regulatory Matters (Summary of Actual Capital Amounts and Ratios for the Company and Its Three Largest Subsidiary Banks) (Details) $ in Millions	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Total capital (to risk-weighted assets), Actual Amount	$ 7,862	$ 7,411
Total capital (to risk-weighted assets), Actual Ratio	0.141	0.132
Total capital (to risk-weighted assets), To be well capitalized, Amount	$ 5,587	$ 5,604
Total capital (to risk-weighted assets), To be well capitalized, Ratio	0.100	0.100
Tier 1 capital (to risk-weighted assets), Actual Amount	$ 6,579	$ 6,285
Tier 1 capital (to risk-weighted assets), Actual Ratio	0.118	0.112
Tier 1 capital (to risk-weighted assets), To be well capitalized, Amount	$ 4,469	$ 4,483
Tier 1 capital (to risk-weighted assets), To be well capitalized, Ratio	0.080	0.080
Common equity tier 1 capital (to risk-weighted assets), Actual Amount	$ 6,013	$ 5,719
Common equity tier 1 capital (to risk-weighted assets), Actual Ratio	0.108	0.102
Common equity tier 1 capital (to risk-weighted assets), To be well capitalized, Amount	$ 3,631	$ 3,643
Common equity tier 1 capital (to risk-weighted assets), To be well capitalized, Ratio	0.065	0.065
Tier 1 capital (to average assets), Actual Amount	$ 6,579	$ 6,285
Tier 1 capital (to average assets), Actual Ratio	0.083	0.092
Tier 1 capital (to average assets), To be well capitalized, Amount	$ 3,944	$ 3,426
Tier 1 capital (to average assets), To be well capitalized, Ratio	0.050	0.050

Regulatory Matters (Capital Rat

Regulatory Matters (Capital Ratios) (Details)	Dec. 31, 2020	Dec. 31, 2019
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Total capital (to risk-weighted assets), Actual Ratio	0.141	0.132
Total capital (to risk-weighted assets), Minimum Capital Ratio	0.080
Total capital (to risk-weighted assets), Capital Conservation Buffer Ratio	0.025
Total capital (to risk-weighted assets), Capital Ratio in Excess of Minimum Capital Ratio plus Capital Conservation Buffer Requirement	0.036
Tier 1 capital (to risk-weighted assets), Actual Ratio	0.118	0.112
Tier 1 capital (to risk-weighted assets), Minimum Capital Ratio	0.060
Tier 1 capital (to risk-weighted assets), Capital Conservation Buffer Ratio	0.025
Tier 1 capital (to risk-weighted assets), Capital Ratio in Excess of Minimum Capital Ratio plus Capital Conservation Buffer Requirement	0.033
Common equity tier 1 capital (to risk-weighted assets), Actual Ratio	0.108	0.102
Common equity tier 1 capital (to risk-weighted assets), Minimum Capital Ratio	0.045
Common equity tier 1 capital (to risk-weighted assets), Capital Conservation Buffer Ratio	0.025
Common equity tier 1 capital (to risk-weighted assets), Capital Ratio in Excess of Minimum Capital Ratio plus Capital Conservation Buffer Requirement	0.038

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details)	12 Months Ended
	Dec. 31, 2020
Broker-Dealer, Net Capital Requirement, SEC Regulation [Abstract]
Increase in Tier 1 risk-based capital ratio	0.0010
Increase in total risk-based capital ratio	0.0010
Increase in tier 1 leverage capital ratio	0.0006

Commitments, Guarantees, Cont_3

Commitments, Guarantees, Contingent Liabilities, and Related Parties (Schedule of Off-Balance Sheet Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Guarantor Obligations [Line Items]
Net unfunded commitments to extend credit	$ 24,217	$ 23,099
Commercial letters of credit	34	5
Total unfunded lending commitments	24,949	23,927
Financial
Guarantor Obligations [Line Items]
Standby letters of credit	531	631
Performance
Guarantor Obligations [Line Items]
Standby letters of credit	$ 167	$ 192

Commitments, Guarantees, Cont_4

Commitments, Guarantees, Contingent Liabilities, and Related Parties (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Guarantor Obligations [Line Items]
Commitments to extend credit expiring in one year	$ 7,700
Standby letters of credit expiring in one year	398
Standby letters of credit, thereafter	300
Letters of credit, accrued liability	6
Reserve for unfunded lending commitments	4
Deferred commitment fees	2
Risk-weighted values assigned to all off-balance sheet financial and derivative instruments	8,500	$ 8,300
Minimum
Guarantor Obligations [Line Items]
Estimate of possible losses	0
Maximum
Guarantor Obligations [Line Items]
Estimate of possible losses	$ 35

Revenue Recognition (Details)

Revenue Recognition (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)state	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)state	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of states in which entity operates | state	11								11
Total noninterest income from contracts with customers (ASC 606)									$ 402	$ 414	$ 412
Other noninterest income (Non-ASC 606 customer related)									147	111	96
Total customer-related fees									549	525	508
Other noninterest income (noncustomer-related)									25	37	44
Total noninterest income	$ 166	$ 157	$ 117	$ 134	$ 152	$ 146	$ 132	$ 132	574	562	552
Other real estate owned income									1	4	1
Net interest income	$ 550	$ 555	$ 563	$ 548	$ 559	$ 567	$ 569	$ 576	2,216	2,272	2,230
Total income less interest expense									2,791	2,838	2,783
Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									125	121	122
Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									113	127	125
Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									68	78	78
Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									12	13	12
Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									59	57	51
Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									25	18	24
Other
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									31	37	37
Other noninterest income (Non-ASC 606 customer related)									15	3	10
Total customer-related fees									46	40	47
Other noninterest income (noncustomer-related)									21	33	41
Total noninterest income									67	73	88
Other real estate owned income									0	0	0
Net interest income									20	24	35
Total income less interest expense									87	97	123
Other | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									2	0	0
Other | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	2	0
Other | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	1	1
Other | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									8	7	6
Other | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	16	14
Other | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									19	11	16
Zions Bank | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									136	134	134
Other noninterest income (Non-ASC 606 customer related)									23	12	12
Total customer-related fees									159	146	146
Other noninterest income (noncustomer-related)									(1)	1	1
Total noninterest income									158	147	147
Other real estate owned income									0	3	1
Net interest income									650	688	662
Total income less interest expense									808	838	810
Zions Bank | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									42	41	41
Zions Bank | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									49	51	50
Zions Bank | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									21	23	24
Zions Bank | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									(1)	0	0
Zions Bank | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									23	17	16
Zions Bank | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									2	2	3
Amegy | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									98	98	96
Other noninterest income (Non-ASC 606 customer related)									34	40	30
Total customer-related fees									132	138	126
Other noninterest income (noncustomer-related)									1	0	0
Total noninterest income									133	138	126
Other real estate owned income									0	0	0
Net interest income									485	489	485
Total income less interest expense									618	627	611
Amegy | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									37	34	34
Amegy | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									24	28	29
Amegy | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									15	17	16
Amegy | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									5	6	6
Amegy | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									16	12	10
Amegy | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	1	1
CB&T | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									56	58	58
Other noninterest income (Non-ASC 606 customer related)									36	28	22
Total customer-related fees									92	86	80
Other noninterest income (noncustomer-related)									3	2	2
Total noninterest income									95	88	82
Other real estate owned income									1	0	0
Net interest income									512	512	508
Total income less interest expense									608	600	590
CB&T | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									22	23	23
CB&T | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									14	16	15
CB&T | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									11	13	14
CB&T | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
CB&T | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									8	4	4
CB&T | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	2	2
NBAZ | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									28	29	30
Other noninterest income (Non-ASC 606 customer related)									12	12	9
Total customer-related fees									40	41	39
Other noninterest income (noncustomer-related)									1	1	0
Total noninterest income									41	42	39
Other real estate owned income									0	0	0
Net interest income									216	223	216
Total income less interest expense									257	265	255
NBAZ | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									7	7	7
NBAZ | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									9	11	11
NBAZ | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									8	8	9
NBAZ | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
NBAZ | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									3	2	2
NBAZ | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	1	1
NSB | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									31	35	35
Other noninterest income (Non-ASC 606 customer related)									12	8	6
Total customer-related fees									43	43	41
Other noninterest income (noncustomer-related)									0	0	0
Total noninterest income									43	43	41
Other real estate owned income									0	1	0
Net interest income									146	148	142
Total income less interest expense									189	192	183
NSB | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									8	8	9
NSB | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									10	12	12
NSB | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									9	11	10
NSB | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
NSB | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									3	3	3
NSB | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	1	1
Vectra | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									19	19	18
Other noninterest income (Non-ASC 606 customer related)									13	7	6
Total customer-related fees									32	26	24
Other noninterest income (noncustomer-related)									0	0	0
Total noninterest income									32	26	24
Other real estate owned income									0	0	0
Net interest income									135	135	130
Total income less interest expense									167	161	154
Vectra | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									6	6	6
Vectra | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									5	6	6
Vectra | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									4	5	4
Vectra | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
Vectra | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									4	2	2
Vectra | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
TCBW | Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									3	4	4
Other noninterest income (Non-ASC 606 customer related)									2	1	1
Total customer-related fees									5	5	5
Other noninterest income (noncustomer-related)									0	0	0
Total noninterest income									5	5	5
Other real estate owned income									0	0	0
Net interest income									52	53	52
Total income less interest expense									57	58	57
TCBW | Operating Segments | Commercial account fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	2	2
TCBW | Operating Segments | Card fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	1	2
TCBW | Operating Segments | Retail and business banking fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
TCBW | Operating Segments | Capital markets and foreign exchange fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									0	0	0
TCBW | Operating Segments | Wealth management and trust fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									1	1	0
TCBW | Operating Segments | Other customer-related fees
Segment Reporting, Revenue Reconciling Item [Line Items]
Total noninterest income from contracts with customers (ASC 606)									$ 0	$ 0	$ 0

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Rate of employee contribution from earnings	80.00%
Matching contribution allocation rate first time	100.00%
Employee contribution rate for first time matching	3.00%
Matching contribution allocation rate second time	50.00%
Employees contribution rate for second time matching	3.00%
Employer contribution in common stock	$ 31	$ 33	$ 29
Minimum range of eligible compensation for noncontributory profit sharing feature	0.00%
Maximum range of eligible compensation for noncontributory profit sharing feature	3.50%
Accrued profit sharing expense	$ 7	16	17
Debt Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets		166
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	28	1	1
Plan assets	0	171	157
Supplemental Employee Retirement Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	0	0	0
Benefit liability	5	5
Plan assets	$ 0	$ 0	$ 0

Retirement Plans (Schedule of N

Retirement Plans (Schedule of Net Periodic Benefit Cost (Credit) for Pension and Postretirement Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	$ 140	$ 138
Interest cost	1	5	$ 6
Actuarial loss	13	8
Annuity purchase	(97)	0
Benefits paid	(57)	(11)
Benefit obligation at end of year	0	140	138
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	171	157
Actual return on plan assets	4	25
Employer contributions	(21)	0
Annuity purchase	(97)	0
Benefits paid	(57)	(11)
Fair value of plan assets at end of year	0	171	157
Funded status	0	31
Amounts recognized in balance sheet:
Asset (liability) for pension/postretirement benefits	0	31
Accumulated other comprehensive income (loss)	0	(17)
Supplemental Employee Retirement Plan, Defined Benefit [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	8	9
Interest cost	0	0	0
Actuarial loss	1	0
Annuity purchase	0	0
Benefits paid	(1)	(1)
Benefit obligation at end of year	8	8	9
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	1	1
Annuity purchase	0	0
Benefits paid	(1)	(1)
Fair value of plan assets at end of year	0	0	0
Funded status	(8)	(8)
Amounts recognized in balance sheet:
Asset (liability) for pension/postretirement benefits	(8)	(8)
Accumulated other comprehensive income (loss)	(3)	(2)
Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	1	1
Interest cost	0	0	0
Actuarial loss	0	0
Annuity purchase	0	0
Benefits paid	0	0
Benefit obligation at end of year	1	1	1
Change in fair value of plan assets:
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	0	0
Annuity purchase	0	0
Benefits paid	0	0
Fair value of plan assets at end of year	0	0	$ 0
Funded status	(1)	(1)
Amounts recognized in balance sheet:
Asset (liability) for pension/postretirement benefits	(1)	(1)
Accumulated other comprehensive income (loss)	$ 0	$ 0

Retirement Plans (Schedule of C

Retirement Plans (Schedule of Components of Net Periodic Benefit Cost (Credit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1	$ 5	$ 6
Expected return on plan assets	(2)	(9)	(11)
Amortization of net actuarial loss	0	0	1
Settlement loss	28	1	1
Net periodic benefit cost	27	(3)	(3)
Supplemental Employee Retirement Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0	0	0
Expected return on plan assets	0	0	0
Amortization of net actuarial loss	0	0	0
Settlement loss	0	0	0
Net periodic benefit cost	0	0	0
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	0	0	0
Expected return on plan assets	0	0	0
Amortization of net actuarial loss	0	0	0
Settlement loss	0	0	0
Net periodic benefit cost	$ 0	$ 0	$ 0

Retirement Plans (Schedule Of W

Retirement Plans (Schedule Of Weighted Average Assumptions Based On The Pension Plan) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Discount rate, benefit obligation	3.20%	4.20%	1.85%
Discount rate, net periodic benefit cost	420.00%	350.00%
Expected long-term return on plan assets, net periodic benefit cost	525.00%	575.00%

Retirement Plans (Schedule of E

Retirement Plans (Schedule of Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2020USD ($)
Supplemental Employee Retirement Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
2021	$ 2
2022	1
2023	1
2024	1
2025	1
Years 2026 – 2030	2
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
2021	0
2022	0
2023	0
2024	0
2025	0
Years 2026 – 2030	$ 0

Retirement Plans (Summary Of Re

Retirement Plans (Summary Of Reconciliation Of The Beginning And Ending Balances Of Assets Measured At Fair Value On A Recurring Basis Using Level 3 Inputs) (Details) - Level 3 - Guaranteed Deposit Account [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets at beginning of year	$ 5	$ 12
Purchases	151	4
Sales	(156)	(11)
Fair value of plan assets at end of year	$ 0	$ 5

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total shares authorized under stock option and incentive plan (in shares)	9,000,000
Number of shares available for future grants of stock options or restricted stock	2,786,162
Share-based compensation expense reduction	$ 1,000	$ 1,000	$ 1,000
Compensation expense not yet recognized for nonvested share-based awards	$ 27,000
Nonvested share-based awards, expected weighted average period to be recognized (in years)	2 years 4 months 24 days
Total intrinsic value of stock options exercised	$ 3,000	13,000	20,000
Cash received from the exercise of stock options	7,000	13,000	18,000
Aggregate intrinsic value of outstanding stock options	14,000	29,000
Aggregate intrinsic value of exercisable options	$ 14,000	29,000
Outstanding stock options, Weighted average remaining contractual life (in years)	3 years 3 months 18 days
Stock options expected to vest (in shares)	546,061
Stock options expected to vest, Weighted average exercise price (in dollars per share)	$ 48.34
Stock options expected to vest, Weighted average remaining life (in years)	5 years 6 months
Stock options expected to vest, Aggregate intrinsic value	$ 12
Total fair value at grant date of restricted stock and RSUs vested	$ 23,000	$ 21,000	$ 21,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding stock options, Weighted average remaining contractual life (in years)	2 years 2 months 12 days	2 years 4 months 24 days
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	586,302	536,489	461,305
Expected to vest (in shares)	812,947
Expected to vest, Aggregate intrinsic value	$ 35,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected to vest (in shares)	57,396
Expected to vest, Aggregate intrinsic value	$ 2,000
Director | Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	28,992	19,116	14,796

Share-Based Compensation (Compe

Share-Based Compensation (Compensation Expense And Related Tax Benefit For All Share-Based Awards) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Compensation expense	$ 26	$ 27	$ 26
Reduction of income tax expense	$ 8	$ 11	$ 14

Share-Based Compensation (Weigh

Share-Based Compensation (Weighted Average Of Fair Value And Significant Assumptions Used In Applying Black-Scholes Model For Options Granted) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Weighted average value for options granted (in dollars per share)	$ 8.18	$ 10.30	$ 12.64
Expected dividend yield	3.00%	2.50%	2.00%
Expected volatility	27.00%	26.00%	27.50%
Risk-free interest rate	1.38%	2.52%	2.62%
Expected life (in years)	5 years	5 years	5 years

Share-Based Compensation (Summa

Share-Based Compensation (Summary of Stock Option Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of shares
Beginning balance (in shares)	1,676,778	2,004,598	2,560,571
Granted (in shares)	320,913	256,818	194,001
Exercised (in shares)	(285,954)	(569,808)	(729,346)
Expired (in shares)	(22,685)	(4,330)	(2,000)
Forfeited (in shares)	(5,395)	(10,500)	(18,628)
Ending balance (in shares)	1,683,657	1,676,778	2,004,598
Weighted average exercise price
Beginning balance (in dollars per share)	$ 34.77	$ 29.85	$ 27.06
Granted (in dollars per share)	45.61	50.80	55.13
Exercised (in dollars per share)	26.48	24.61	26.79
Expired (in dollars per share)	30.17	22.37	25.74
Forfeited (in dollars per share)	51.34	43.13	31.11
Ending balance (in dollars per share)	$ 38.26	$ 34.77	$ 29.85
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Number of shares, Outstanding stock options exercisable (in shares)	1,137,596	1,239,821	1,448,244
Weighted average exercise price, Outstanding stock options exercisable (in dollars per share)	$ 33.42	$ 28.95	$ 26.68

Share-Based Compensation (Sched

Share-Based Compensation (Schedule of Additional Selected Information on Stock Options) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding stock options, Number of shares (in shares)	1,683,657	1,676,778	2,004,598	2,560,571
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 38.26	$ 34.77	$ 29.85	$ 27.06
Outstanding stock options, Weighted average remaining contractual life (in years)	3 years 3 months 18 days
Exercisable stock options, Number of shares (in shares)	1,137,596	1,239,821	1,448,244
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 33.42	$ 28.95	$ 26.68
Stock options without a fixed expiration date (in shares)	10,867
$4.15 to $19.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	$ 4.15
Exercise price range, upper range limit (in dollars per share)	$ 19.99
Outstanding stock options, Number of shares (in shares)	10,867
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 6.22
Outstanding stock options, Weighted average remaining contractual life (in years)
Exercisable stock options, Number of shares (in shares)	10,867
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 6.22
$20.00 to $24.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	20
Exercise price range, upper range limit (in dollars per share)	$ 24.99
Outstanding stock options, Number of shares (in shares)	276,809
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 21.03
Outstanding stock options, Weighted average remaining contractual life (in years)	2 years 1 month 6 days
Exercisable stock options, Number of shares (in shares)	276,809
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 21.03
$25.00 to $29.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	25
Exercise price range, upper range limit (in dollars per share)	$ 29.99
Outstanding stock options, Number of shares (in shares)	450,709
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 28.53
Outstanding stock options, Weighted average remaining contractual life (in years)	1 year 1 month 6 days
Exercisable stock options, Number of shares (in shares)	450,031
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 28.53
$30.00 to $39.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	30
Exercise price range, upper range limit (in dollars per share)	$ 39.99
Outstanding stock options, Number of shares (in shares)	22,225
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 30.10
Outstanding stock options, Weighted average remaining contractual life (in years)	4 months 24 days
Exercisable stock options, Number of shares (in shares)	22,225
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 30.10
$40.00 to $44.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	40
Exercise price range, upper range limit (in dollars per share)	$ 44.99
Outstanding stock options, Number of shares (in shares)	173,351
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 44.10
Outstanding stock options, Weighted average remaining contractual life (in years)	3 years
Exercisable stock options, Number of shares (in shares)	171,290
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 44.12
$45.00 to $49.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	45
Exercise price range, upper range limit (in dollars per share)	$ 49.99
Outstanding stock options, Number of shares (in shares)	318,954
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 45.65
Outstanding stock options, Weighted average remaining contractual life (in years)	6 years 1 month 6 days
Exercisable stock options, Number of shares (in shares)	0
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 0
$50.00 to $55.68
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price range, lower range limit (in dollars per share)	50
Exercise price range, upper range limit (in dollars per share)	$ 55.68
Outstanding stock options, Number of shares (in shares)	430,742
Outstanding stock options, Weighted average exercise price (in dollars per share)	$ 52.90
Outstanding stock options, Weighted average remaining contractual life (in years)	4 years 6 months
Exercisable stock options, Number of shares (in shares)	206,374
Exercisable stock options, Weighted average exercise price (in dollars per share)	$ 53.58

Share-Based Compensation (Sum_2

Share-Based Compensation (Summary of Restricted Stock Activity) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of shares
Beginning balance (in shares)	50,457	45,686	38,978
Issued (in shares)	27,798	24,994	21,634
Vested (in shares)	(20,859)	(20,223)	(14,836)
Forfeited (in shares)			(90)
Ending balance (in shares)	57,396	50,457	45,686
Weighted average fair value
Beginning balance (in dollars per share)	$ 39.50	$ 33.78	$ 25.91
Issued (in dollars per share)	45.65	42.83	42.90
Vested (in dollars per share)	34.77	30.69	26.27
Forfeited (in dollars per share)			55.68
Ending balance (in dollars per share)	$ 44.20	$ 39.50	$ 33.78

Share Based Compensation (Summa

Share Based Compensation (Summary of Restricted Stock Unit Activity) (Details) - Restricted Stock Units - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of shares
Beginning balance (in shares)	1,294,070	1,400,699	1,709,813
Granted (in shares)	586,302	536,489	461,305
Vested (in shares)	(593,375)	(614,968)	(699,920)
Forfeited (in shares)	(44,676)	(28,150)	(70,499)
Ending balance (in shares)	1,242,321	1,294,070	1,400,699
Weighted average fair value
Beginning balance (in dollars per share)	$ 43.59	$ 37.65	$ 30.08
Issued (in dollars per share)	42.75	47.85	53.17
Vested (in dollars per share)	37.56	33.74	29.56
Forfeited (in dollars per share)	47.78	44.69	35.95
Ending balance (in dollars per share)	$ 46.31	$ 43.59	$ 37.65

Income Taxes (Schedule of Incom

Income Taxes (Schedule of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal:
Current	$ 153	$ 195	$ 210
Deferred	(47)	(1)	(1)
Total Federal	106	194	209
State:
Current	38	44	49
Deferred	(11)	(1)	1
Total State	27	43	50
Total	$ 133	$ 237	$ 259

Income Taxes (Schedule of Statu

Income Taxes (Schedule of Statutory Federal Income Tax Rate Reconciles to Actual Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax expense at statutory federal rate	$ 141	$ 221	$ 240
State income taxes including credits, net	21	34	40
Other nondeductible expenses	8	13	15
Nontaxable income	(32)	(28)	(24)
Share-based compensation	(1)	(4)	(7)
Tax credits and other taxes	(4)	1	(5)
Total	$ 133	$ 237	$ 259

Income Taxes (Schedule of Tax E

Income Taxes (Schedule of Tax Effects of Deferred Tax Assets and Deferred Tax Liabilities) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Gross deferred tax assets:
Book loan loss deduction in excess of tax	$ 205,000,000	$ 137,000,000
Pension and postretirement	1,000,000	5,000,000
Deferred compensation	71,000,000	72,000,000
Lease liabilities	59,000,000	61,000,000
Other	24,000,000	35,000,000
Total deferred tax assets before valuation allowance	360,000,000	310,000,000
Valuation allowance	0	0
Total deferred tax assets	360,000,000	310,000,000
Gross deferred tax liabilities:
Premises and equipment, due to differences in depreciation	(81,000,000)	(66,000,000)
Federal Home Loan Bank stock dividends	(2,000,000)	(2,000,000)
Leasing operations	(55,000,000)	(52,000,000)
Prepaid expenses	(6,000,000)	(6,000,000)
Prepaid pension reserves	(6,000,000)	(12,000,000)
Mortgage servicing	(8,000,000)	(7,000,000)
Security investments and derivative fair value adjustments	(102,000,000)	(17,000,000)
Deferred loan fees	(32,000,000)	(30,000,000)
ROU assets	(53,000,000)	(55,000,000)
Equity investments	(18,000,000)	(26,000,000)
Total deferred tax liabilities	(363,000,000)	(273,000,000)
Net deferred tax assets (liabilities)	$ (3,000,000)
Net deferred tax assets (liabilities)		$ 37,000,000

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Income Tax Contingency [Line Items]
Valuation allowance	$ 0	$ 0
Unrecognized tax benefits that would impact effective tax rate	10,000,000	10,000,000
Income tax penalties and interest accrued	1,000,000	$ 1,000,000
Maximum
Income Tax Contingency [Line Items]
Tax effect of remaining net operating loss and tax credit carryforward	$ 1,000,000

Income Taxes (Schedule of Recon

Income Taxes (Schedule of Reconciliation of Gross Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 14	$ 8	$ 6
Tax positions related to current year, Additions	2	2	1
Tax positions related to current year, Reductions	0	0	0
Tax positions related to prior years, Additions	0	4	1
Tax positions related to prior years, Reductions	(5)	0	0
Settlements with taxing authorities	0	0	0
Lapses in statutes of limitations	0	0	0
Balance at end of year	$ 11	$ 14	$ 8

Net Earnings Per Common Share_2

Net Earnings Per Common Share (Basic And Diluted Net Earnings Per Common Share Based On The Weighted Average Outstanding Shares) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic:
Net income	$ 284	$ 175	$ 66	$ 14	$ 183	$ 222	$ 198	$ 213	$ 539	$ 816	$ 884
Less common and preferred dividends									259	260	236
Undistributed earnings									280	556	648
Less undistributed earnings applicable to nonvested shares									2	4	5
Undistributed earnings applicable to common shares									278	552	643
Distributed earnings applicable to common shares									223	224	200
Total earnings applicable to common shares									$ 501	$ 776	$ 843
Weighted average common shares outstanding (in shares)									163,737	175,984	193,589
Net earnings per common share (in dollars per share)	$ 1.66	$ 1.01	$ 0.34	$ 0.04	$ 1.03	$ 1.23	$ 1.05	$ 1.10	$ 3.06	$ 4.41	$ 4.36
Diluted:
Dilutive effect of common stock warrants (in shares)									1,641	9,926	11,959
Dilutive effect of stock options (in shares)									235	594	953
Weighted average diluted common shares outstanding (in shares)									165,613	186,504	206,501
Net earnings per common share (in dollars per share)	$ 1.66	$ 1.01	$ 0.34	$ 0.04	$ 0.97	$ 1.17	$ 0.99	$ 1.04	$ 3.02	$ 4.16	$ 4.08

Net Earnings Per Common Share_3

Net Earnings Per Common Share (Stock Awards That Were Anti-Dilutive) (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted stock and restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,338	1,390	1,602
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	889	460	151

Operating Segment Information_2

Operating Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)branch	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)branchsegment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment									7
Number of branches | branch	422								422
Net interest income	$ 550	$ 555	$ 563	$ 548	$ 559	$ 567	$ 569	$ 576	$ 2,216	$ 2,272	$ 2,230
Provision for credit losses	(67)	55	168	258	4	10	21	4	414	39	(40)
Net interest income after provision for credit losses									1,802	2,233	2,270
Noninterest income	166	157	117	134	152	146	132	132	574	562	552
Noninterest expense	424	442	430	408	472	415	424	430	1,704	1,742	1,679
Income before income taxes	$ 359	$ 215	$ 82	$ 16	$ 235	$ 288	$ 256	$ 274	672	1,053	1,143
Total average loans									53,016	48,265	45,425
Total average deposits									63,689	55,081	53,183
Other
Segment Reporting Information [Line Items]
Net interest income									20	24	35
Provision for credit losses									3	2	0
Net interest income after provision for credit losses									17	22	35
Noninterest income									67	73	88
Noninterest expense									205	180	145
Income before income taxes									(121)	(85)	(22)
Total average loans									629	451	347
Total average deposits									2,495	2,910	2,536
Zions Bank | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									650	688	662
Provision for credit losses									67	18	8
Net interest income after provision for credit losses									583	670	654
Noninterest income									158	147	147
Noninterest expense									446	471	460
Income before income taxes									295	346	341
Total average loans									13,845	13,109	12,643
Total average deposits									18,370	15,561	15,149
Amegy | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									485	489	485
Provision for credit losses									111	9	(80)
Net interest income after provision for credit losses									374	480	565
Noninterest income									133	138	126
Noninterest expense									329	344	344
Income before income taxes									178	274	347
Total average loans									13,114	12,235	11,358
Total average deposits									12,970	11,627	11,160
CB&T | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									512	512	508
Provision for credit losses									120	7	15
Net interest income after provision for credit losses									392	505	493
Noninterest income									95	88	82
Noninterest expense									305	316	308
Income before income taxes									182	277	267
Total average loans									12,366	10,763	10,033
Total average deposits									13,763	11,522	11,268
NBAZ | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									216	223	216
Provision for credit losses									35	2	8
Net interest income after provision for credit losses									181	221	208
Noninterest income									41	42	39
Noninterest expense									147	156	152
Income before income taxes									75	107	95
Total average loans									5,099	4,774	4,608
Total average deposits									5,771	5,002	4,931
NSB | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									146	148	142
Provision for credit losses									37	(1)	1
Net interest income after provision for credit losses									109	149	141
Noninterest income									43	43	41
Noninterest expense									141	145	143
Income before income taxes									11	47	39
Total average loans									3,102	2,630	2,394
Total average deposits									5,427	4,512	4,286
Vectra | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									135	135	130
Provision for credit losses									34	3	6
Net interest income after provision for credit losses									101	132	124
Noninterest income									32	26	24
Noninterest expense									109	108	105
Income before income taxes									24	50	43
Total average loans									3,401	3,109	2,924
Total average deposits									3,637	2,853	2,761
TCBW | Operating Segments
Segment Reporting Information [Line Items]
Net interest income									52	53	52
Provision for credit losses									7	(1)	2
Net interest income after provision for credit losses									45	54	50
Noninterest income									5	5	5
Noninterest expense									22	22	22
Income before income taxes									28	37	33
Total average loans									1,460	1,194	1,118
Total average deposits									$ 1,256	$ 1,094	$ 1,092
Utah | Zions Bank
Segment Reporting Information [Line Items]
Number of branches | branch	95								95
Idaho | Zions Bank
Segment Reporting Information [Line Items]
Number of branches | branch	25								25
Wyoming | Zions Bank
Segment Reporting Information [Line Items]
Number of branches | branch	1								1
California | CB&T
Segment Reporting Information [Line Items]
Number of branches | branch	85								85
Texas | Amegy
Segment Reporting Information [Line Items]
Number of branches | branch	76								76
Arizona | NBAZ
Segment Reporting Information [Line Items]
Number of branches | branch	56								56
Nevada | NSB
Segment Reporting Information [Line Items]
Number of branches | branch	46								46
Colorado | Vectra
Segment Reporting Information [Line Items]
Number of branches | branch	34								34
New Mexico | Vectra
Segment Reporting Information [Line Items]
Number of branches | branch	1								1
Washington | TCBW
Segment Reporting Information [Line Items]
Number of branches | branch	2								2
Oregon | TCBW
Segment Reporting Information [Line Items]
Number of branches | branch	1								1

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Financial Information by Quarter) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Gross interest income	$ 571	$ 581	$ 595	$ 622	$ 647	$ 677	$ 684	$ 675	$ 2,368	$ 2,683	$ 2,481
Net interest income	550	555	563	548	559	567	569	576	2,216	2,272	2,230
Provision for credit losses	(67)	55	168	258	4	10	21	4	414	39	(40)
Noninterest income	166	157	117	134	152	146	132	132	574	562	552
Noninterest expense	424	442	430	408	472	415	424	430	1,704	1,742	1,679
Income before income taxes	359	215	82	16	235	288	256	274	672	1,053	1,143
Net income	284	175	66	14	183	222	198	213	539	816	884
Preferred stock dividends	(9)	(8)	(9)	(8)	(9)	(8)	(9)	(8)	(34)	(34)	(34)
Net earnings applicable to common shareholders	$ 275	$ 167	$ 57	$ 6	$ 174	$ 214	$ 189	$ 205	$ 505	$ 782	$ 850
Net earnings per common share:
Basic (in dollars per share)	$ 1.66	$ 1.01	$ 0.34	$ 0.04	$ 1.03	$ 1.23	$ 1.05	$ 1.10	$ 3.06	$ 4.41	$ 4.36
Diluted (in dollars per share)	$ 1.66	$ 1.01	$ 0.34	$ 0.04	$ 0.97	$ 1.17	$ 0.99	$ 1.04	$ 3.02	$ 4.16	$ 4.08

Uncategorized Items - zions-202

Label	Element	Value
Accounting Standards Update [Extensible List]	us-gaap_AccountingStandardsUpdateExtensibleList	us-gaap:AccountingStandardsUpdate201409Member