10-Q

United States

Securities and Exchange Commission

Washington, D.C. 20549

Form 10-Q

☒ Quarterly Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the quarterly period ended: March 31, 2022

Or

☐ Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the transition period from ________________ to ________________

Commission file number: 001-13221

Cullen/Frost Bankers, Inc.

(Exact name of registrant as specified in its charter)

Texas			74-1751768
(State or other jurisdiction of incorporation or organization)			(I.R.S. Employer Identification No.)
111 W. Houston Street,	San Antonio,	Texas	78205
(Address of principal executive offices)			(Zip code)

	(210)	220-4011
(Registrant's telephone number, including area code)

N/A

(Former name, former address and former fiscal year, if changed since last report

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $.01 Par Value	CFR	New York Stock Exchange
Depositary Shares, each representing a 1/40th interest in a share of 4.450% Non-Cumulative Perpetual Preferred Stock, Series B	CFR.PrB	New York Stock Exchange

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.     Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).    Yes  ☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☒	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
		Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.    ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☒

As of April 21, 2022 there were 64,097,017 shares of the registrant’s Common Stock, $.01 par value, outstanding.

Cullen/Frost Bankers, Inc.

Quarterly Report on Form 10-Q

March 31, 2022

Table of Contents

		Page
Part I - Financial Information
Item 1.	Financial Statements (Unaudited)
	Consolidated Balance Sheets	3
	Consolidated Statements of Income	4
	Consolidated Statements of Comprehensive Income (Loss)	5
	Consolidated Statements of Changes in Shareholders’ Equity	6
	Consolidated Statements of Cash Flows	7
	Notes to Consolidated Financial Statements	8
Item 2.	Management's Discussion and Analysis of Financial Condition and Results of Operations	34
Item 3.	Quantitative and Qualitative Disclosures About Market Risk	56
Item 4.	Controls and Procedures	57
Part II - Other Information
Item 1.	Legal Proceedings	58
Item 1A.	Risk Factors	58
Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds	58
Item 3.	Defaults Upon Senior Securities	58
Item 4.	Mine Safety Disclosures	58
Item 5.	Other Information	58
Item 6.	Exhibits	59
Signatures		60

2

Part I. Financial Information

Item 1. Financial Statements (Unaudited)

Cullen/Frost Bankers, Inc.

Consolidated Balance Sheets

(Dollars in thousands, except per share amounts)

	March 31, 2022		December 31, 2021
Assets:
Cash and due from banks	$	772,095	$	555,778
Interest-bearing deposits	13,684,988		15,985,244
Federal funds sold	—		34,075
Resell agreements	—		7,903
Total cash and cash equivalents	14,457,083		16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at March 31, 2022 and $158 at December 31, 2021	1,665,465		1,749,179
Securities available for sale, at estimated fair value	16,184,539		13,924,628
Trading account securities	29,518		25,162
Loans, net of unearned discounts	16,542,537		16,336,397
Less: Allowance for credit losses on loans	(246,835)		(248,666)
Net loans	16,295,702		16,087,731
Premises and equipment, net	1,046,410		1,050,331
Goodwill	654,952		654,952
Other intangible assets, net	720		866
Cash surrender value of life insurance policies	189,471		190,139
Accrued interest receivable and other assets	772,191		612,502
Total assets	$	51,296,051	$	50,878,490
Liabilities:
Deposits:
Non-interest-bearing demand deposits	$	18,114,430	$	18,423,018
Interest-bearing deposits	26,316,499		24,272,678
Total deposits	44,430,929		42,695,696
Federal funds purchased	35,200		25,925
Repurchase agreements	1,842,618		2,740,799
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,026		123,011
Subordinated notes, net of unamortized issuance costs	99,217		99,178
Accrued interest payable and other liabilities	988,769		754,326
Total liabilities	47,519,759		46,438,935
Shareholders’ Equity:
Preferred stock, par value $0.01 per share; 10,000,000 shares authorized; 150,000 Series B shares ($1,000 liquidation preference) issued at March 31, 2022 and December 31, 2021	145,452		145,452
Common stock, par value $0.01 per share; 210,000,000 shares authorized; 64,236,306 shares issued at March 31, 2022 and December 31, 2021	642		642
Additional paid-in capital	1,012,033		1,009,921
Retained earnings	3,002,642		2,956,966
Accumulated other comprehensive income (loss), net of tax	(371,790)		347,318
Treasury stock, at cost; 142,099 shares at March 31, 2022 and 250,070 shares at December 31, 2021	(12,687)		(20,744)
Total shareholders’ equity	3,776,292		4,439,555
Total liabilities and shareholders’ equity	$	51,296,051	$	50,878,490

See Notes to Consolidated Financial Statements.

3

Cullen/Frost Bankers, Inc.

Consolidated Statements of Income

(Dollars in thousands, except per share amounts)

	Three Months Ended March 31,
	2022		2021
Interest income:
Loans, including fees	$	149,977	$	167,483
Securities:
Taxable	43,058		20,028
Tax-exempt	56,866		56,663
Interest-bearing deposits	6,343		2,433
Federal funds sold	13		3
Resell agreements	4		1
Total interest income	256,261		246,611
Interest expense:
Deposits	4,912		3,517
Federal funds purchased	12		8
Repurchase agreements	518		395
Junior subordinated deferrable interest debentures	584		646
Subordinated notes	1,164		1,164
Total interest expense	7,190		5,730
Net interest income	249,071		240,881
Credit loss expense	—		63
Net interest income after credit loss expense	249,071		240,818
Non-interest income:
Trust and investment management fees	38,656		35,314
Service charges on deposit accounts	22,740		19,993
Insurance commissions and fees	16,608		17,313
Interchange and card transaction fees	4,226		4,093
Other charges, commissions and fees	9,627		8,304
Net gain (loss) on securities transactions	—		—
Other	9,533		8,219
Total non-interest income	101,390		93,236
Non-interest expense:
Salaries and wages	111,329		93,458
Employee benefits	24,220		22,536
Net occupancy	27,411		26,051
Technology, furniture and equipment	29,157		28,016
Deposit insurance	3,633		2,928
Intangible amortization	146		202
Other	42,836		36,951
Total non-interest expense	238,732		210,142
Income before income taxes	111,729		123,912
Income taxes	12,627		7,897
Net income	99,102		116,015
Preferred stock dividends	1,669		2,151
Net income available to common shareholders	$	97,433	$	113,864
Earnings per common share:
Basic	$	1.51	$	1.78
Diluted	1.50		1.77

See Notes to Consolidated Financial Statements.

4

Cullen/Frost Bankers, Inc.

Consolidated Statements of Comprehensive Income (Loss)

(Dollars in thousands)

	Three Months Ended March 31,
	2022		2021
Net income	$	99,102	$	116,015
Other comprehensive income (loss), before tax:
Securities available for sale and transferred securities:
Change in net unrealized gain/loss during the period	(910,795)		(159,779)
Change in net unrealized gain on securities transferred to held to maturity	(209)		(259)
Reclassification adjustment for net (gains) losses included in net income	—		—
Total securities available for sale and transferred securities	(911,004)		(160,038)
Defined-benefit post-retirement benefit plans:
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit)	741		1,529
Total defined-benefit post-retirement benefit plans	741		1,529
Other comprehensive income (loss), before tax	(910,263)		(158,509)
Deferred tax expense (benefit)	(191,155)		(33,287)
Other comprehensive income (loss), net of tax	(719,108)		(125,222)
Comprehensive income (loss)	$	(620,006)	$	(9,207)

See Notes to Consolidated Financial Statements.

5

Cullen/Frost Bankers, Inc.

Consolidated Statements of Changes in Shareholders’ Equity

(Dollars in thousands, except per share amounts)

	Preferred Stock		Common Stock		Additional Paid-In Capital		Retained Earnings		Accumulated Other Comprehensive Income (Loss), Net of Tax		Treasury Stock		Total
Three months ended:
March 31, 2022
Balance at beginning of period	$	145,452	$	642	$	1,009,921	$	2,956,966	$	347,318	$	(20,744)	$	4,439,555
Net income	—		—		—		99,102		—		—		99,102
Other comprehensive income (loss), net of tax	—		—		—		—		(719,108)		—		(719,108)
Stock option exercises/stock unit conversions (115,430 shares)	—		—		—		(3,314)		—		9,053		5,739
Stock-based compensation expense recognized in earnings	—		—		2,112		—		—		—		2,112
Purchase of treasury stock (7,459 shares)	—		—		—		—		—		(996)		(996)
Cash dividends – Series B preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depositary share)	—		—		—		(1,669)		—		—		(1,669)
Cash dividends – common stock ($0.75 per share)	—		—		—		(48,443)		—		—		(48,443)
Balance at end of period	$	145,452	$	642	$	1,012,033	$	3,002,642	$	(371,790)	$	(12,687)	$	3,776,292
March 31, 2021
Balance at beginning of period	$	145,452	$	642	$	997,168	$	2,750,723	$	512,970	$	(113,939)	$	4,293,016
Net income	—		—		—		116,015		—		—		116,015
Other comprehensive income (loss), net of tax	—		—		—		—		(125,222)		—		(125,222)
Stock option exercises/stock unit conversions (513,824 shares)	—		—		—		(21,342)		—		50,739		29,397
Stock-based compensation expense recognized in earnings	—		—		2,526		—		—		—		2,526
Purchase of treasury stock (11,625 shares)	—		—		—		—		—		(1,288)		(1,288)
Treasury stock issued to the 401(k) stock purchase plan (18,555 shares)	—		—		—		(57)		—		1,806		1,749
Cash dividends – Series B preferred stock (approximately $14.34 per share which is equivalent to approximately $0.36 per depositary share)	—		—		—		(2,151)		—		—		(2,151)
Cash dividends – common stock ($0.72 per share)	—		—		—		(46,124)		—		—		(46,124)
Balance at end of period	$	145,452	$	642	$	999,694	$	2,797,064	$	387,748	$	(62,682)	$	4,267,918

See accompanying Notes to Consolidated Financial Statements

6

Cullen/Frost Bankers, Inc.

Consolidated Statements of Cash Flows

(Dollars in thousands)

	Three Months Ended March 31,
	2022		2021
Operating Activities:
Net income	$	99,102	$	116,015
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	—		63
Deferred tax expense (benefit)	(432)		4,172
Accretion of loan discounts	(2,945)		(3,425)
Securities premium amortization (discount accretion), net	27,654		30,598
Net (gain) loss on securities transactions	—		—
Depreciation and amortization	17,551		16,941
Net (gain) loss on sale/write-down of assets/foreclosed assets	130		(134)
Stock-based compensation	2,112		2,526
Net tax benefit from stock-based compensation	1,244		3,136
Earnings on life insurance policies	(533)		(740)
Net change in:
Trading account securities	139		(2,153)
Lease right-of-use assets	5,970		5,889
Accrued interest receivable and other assets	(55,232)		73,164
Accrued interest payable and other liabilities	238,065		(26,287)
Net cash from operating activities	332,825		219,765
Investing Activities:
Securities held to maturity:
Purchases	(31,545)		—
Maturities, calls and principal repayments	111,211		120,029
Securities available for sale:
Purchases	(3,356,279)		(455,091)
Sales	—		—
Maturities, calls and principal repayments	236,032		351,612
Net change in loans	(209,490)		(406,836)
Benefits received on life insurance policies	1,201		968
Proceeds from sales of premises and equipment	1		3
Purchases of premises and equipment	(12,374)		(12,814)
Proceeds from sales of repossessed properties	1,543		100
Net cash from investing activities	(3,259,700)		(402,029)
Financing Activities:
Net change in deposits	1,735,233		1,909,419
Net change in short-term borrowings	(888,906)		(193,573)
Proceeds from stock option exercises	5,739		29,397
Purchase of treasury stock	(996)		(1,288)
Cash dividends paid on preferred stock	(1,669)		(2,151)
Cash dividends paid on common stock	(48,443)		(46,124)
Net cash from financing activities	800,958		1,695,680
Net change in cash and cash equivalents	(2,125,917)		1,513,416
Cash and cash equivalents at beginning of period	16,583,000		10,288,853
Cash and cash equivalents at end of period	$	14,457,083	$	11,802,269

See Notes to Consolidated Financial Statements.

7

Notes to Consolidated Financial Statements

(Table amounts in thousands, except for share and per share amounts)

Note 1 - Significant Accounting Policies

Nature of Operations. Cullen/Frost Bankers, Inc. (“Cullen/Frost”) is a financial holding company and a bank holding company headquartered in San Antonio, Texas that provides, through its subsidiaries, a broad array of products and services throughout numerous Texas markets. The terms “Cullen/Frost,” “the Corporation,” “we,” “us” and “our” mean Cullen/Frost Bankers, Inc. and its subsidiaries, when appropriate. In addition to general commercial and consumer banking, other products and services offered include trust and investment management, insurance, brokerage, mutual funds, leasing, treasury management, capital markets advisory and item processing.

Basis of Presentation. The consolidated financial statements in this Quarterly Report on Form 10-Q include the accounts of Cullen/Frost and all other entities in which Cullen/Frost has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. The accounting and financial reporting policies we follow conform, in all material respects, to accounting principles generally accepted in the United States and to general practices within the financial services industry.

The consolidated financial statements in this Quarterly Report on Form 10-Q have not been audited by an independent registered public accounting firm, but in the opinion of management, reflect all adjustments necessary for a fair presentation of our financial position and results of operations. All such adjustments were of a normal and recurring nature. The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q adopted by the Securities and Exchange Commission (“SEC”). Accordingly, the financial statements do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements and should be read in conjunction with our consolidated financial statements, and notes thereto, for the year ended December 31, 2021, included in our Annual Report on Form 10-K filed with the SEC on February 4, 2022 (the “2021 Form 10-K”). Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year or any future period.

Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. The allowance for loan losses and the fair values of financial instruments and the status of contingencies are particularly subject to change.

Cash Flow Reporting. Additional cash flow information was as follows:

	Three Months Ended March 31,
	2022		2021
Cash paid for interest	$	8,069	$	9,719
Cash paid for income taxes	—		—
Significant non-cash transactions:
Unsettled securities transactions	78,769		21,957
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities	4,013		1,326
Treasury stock issued to 401(k) stock purchase plan	—		1,749

Accounting Changes, Reclassifications and Restatements. Certain items in prior financial statements have been reclassified to conform to the current presentation.

8

Note 2 - Securities

Securities - Held to Maturity. A summary of the amortized cost, fair value and allowance for credit losses related to securities held to maturity as of March 31, 2022 and December 31, 2021 is presented below.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Allowance for Credit Losses		Net Carrying Amount
March 31, 2022
Residential mortgage-backed securities	$	526,969	$	—	$	17,519	$	509,450	$	—	$	526,969
States and political subdivisions	1,137,154		3,622		11,717		1,129,059		(158)		1,136,996
Other	1,500		—		16		1,484		—		1,500
Total	$	1,665,623	$	3,622	$	29,252	$	1,639,993	$	(158)	$	1,665,465
December 31, 2021
Residential mortgage-backed securities	$	527,264	$	18,766	$	—	$	546,030	$	—	$	527,264
States and political subdivisions	1,220,573		41,141		101		1,261,613		(158)		1,220,415
Other	1,500		—		—		1,500		—		1,500
Total	$	1,749,337	$	59,907	$	101	$	1,809,143	$	(158)	$	1,749,179

All mortgage-backed securities included in the above table were issued by U.S. government agencies and corporations. The carrying value of held-to-maturity securities pledged to secure public funds, trust deposits, repurchase agreements and for other purposes, as required or permitted by law was $252.0 million and $642.3 million at March 31, 2022 and December 31, 2021, respectively. Accrued interest receivable on held-to-maturity securities totaled $10.0 million and $18.4 million at March 31, 2022 and December 31, 2021, respectively and is included in accrued interest receivable and other assets in the accompanying consolidated balance sheets.

From time to time, we have reclassified certain securities from available for sale to held to maturity. The net unamortized, unrealized gain remaining on transferred securities included in accumulated other comprehensive income in the accompanying balance sheet totaled $2.3 million ($1.8 million, net of tax) at March 31, 2022 and $2.5 million ($2.0 million, net of tax) at December 31, 2021. This amount will be amortized out of accumulated other comprehensive income over the remaining life of the underlying securities as an adjustment of the yield on those securities.

The following table summarizes Moody's and/or Standard & Poor's bond ratings for our portfolio of held-to-maturity securities issued by States and political subdivisions and other securities as of March 31, 2022 and December 31, 2021:

	States and Political Subdivisions
	Not Guaranteed or Pre-Refunded		Guaranteed by the Texas PSF		Pre-Refunded		Total		Other Securities
March 31, 2022
Aaa/AAA	$	91,034	$	467,039	$	471,183	$	1,029,256	$	—
Aa/AA	107,898		—		—		107,898		—
Not rated	—		—		—		—		1,500
Total	$	198,932	$	467,039	$	471,183	$	1,137,154	$	1,500
December 31, 2021
Aaa/AAA	$	92,379	$	460,648	$	563,251	$	1,116,278	$	—
Aa/AA	104,295		—		—		104,295		—
Not rated	—		—		—		—		1,500
Total	$	196,674	$	460,648	$	563,251	$	1,220,573	$	1,500

9

The following table details activity in the allowance for credit losses on held-to-maturity securities during the three months ended March 31, 2022 and 2021.

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	158	$	160
Credit loss expense (benefit)	—		(2)
Ending balance	$	158	$	158

Securities - Available for Sale. A summary of the amortized cost, fair value and allowance for credit losses related to securities available for sale as of March 31, 2022 and December 31, 2021 is presented below.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Allowance for Credit Losses		Estimated Fair Value
March 31, 2022
U.S. Treasury	$	3,658,506	$	1,883	$	152,643	$	—	$	3,507,746
Residential mortgage-backed securities	5,696,906		7,246		328,113		—		5,376,039
States and political subdivisions	7,218,821		135,206		95,634		—		7,258,393
Other	42,361		—		—		—		42,361
Total	$	16,616,594	$	144,335	$	576,390	$	—	$	16,184,539
December 31, 2021
U.S. Treasury	$	2,165,702	$	23,333	$	9,602	$	—	$	2,179,433
Residential mortgage-backed securities	4,059,692		31,662		25,089		—		4,066,265
States and political subdivisions	7,178,135		463,810		5,374		—		7,636,571
Other	42,359		—		—		—		42,359
Total	$	13,445,888	$	518,805	$	40,065	$	—	$	13,924,628

All mortgage-backed securities included in the above table were issued by U.S. government agencies and corporations. At March 31, 2022, all of the securities in our available for sale municipal bond portfolio were issued by the State of Texas or political subdivisions or agencies within the State of Texas, of which approximately 75.7% are either guaranteed by the PSF or have been pre-refunded. Securities with limited marketability, such as stock in the Federal Reserve Bank and the Federal Home Loan Bank, are carried at cost and are reported as other available for sale securities in the table above. The carrying value of available-for-sale securities pledged to secure public funds, trust deposits, repurchase agreements and for other purposes, as required or permitted by law was $4.8 billion and $5.8 billion at March 31, 2022 and December 31, 2021, respectively. Accrued interest receivable on available-for-sale securities totaled $80.8 million and $120.5 million at March 31, 2022 and December 31, 2021, respectively, and is included in accrued interest receivable and other assets in the accompanying consolidated balance sheets.

The table below summarizes, as of March 31, 2022, securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded, aggregated by type of security and length of time in a continuous unrealized loss position.

	Less than 12 Months				More than 12 Months				Total
	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
U.S. Treasury	$	3,220,375	$	152,643	$	—	$	—	$	3,220,375	$	152,643
Residential mortgage-backed securities	4,583,657		286,421		402,940		41,692		4,986,597		328,113
States and political subdivisions	1,233,614		93,136		13,602		2,498		1,247,216		95,634
Total	$	9,037,646	$	532,200	$	416,542	$	44,190	$	9,454,188	$	576,390

As of March 31, 2022, no allowance for credit losses has been recognized on available for sale securities in an unrealized loss position as management does not believe any of the securities are impaired due to reasons of credit quality. This is based upon our analysis of the underlying risk characteristics, including credit ratings, and other qualitative factors related to our available for sale securities and in consideration of our historical credit loss experience and internal forecasts. The issuers of these securities continue to make timely principal and interest payments under the contractual terms of the securities. Furthermore, management does not have the intent to sell any of the securities classified as available for sale in the table above and believes that it is more likely than not that we will not have to sell any such securities before a recovery of cost. The

10

unrealized losses are due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline.

Contractual Maturities. The following table summarizes the maturity distribution schedule of securities held to maturity and securities available for sale as of March 31, 2022. Mortgage-backed securities are included in maturity categories based on their stated maturity date. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. Other securities classified as available for sale include stock in the Federal Reserve Bank and the Federal Home Loan Bank, which have no maturity date. These securities have been included in the total column only.

	Within 1 Year		1 - 5 Years		5 - 10 Years		After 10 Years		Total
Held To Maturity
Amortized Cost
Residential mortgage-backed securities	$	16	$	—	$	514,842	$	12,111	$	526,969
States and political subdivisions	429,852		118,516		56,735		532,051		1,137,154
Other	—		1,500		—		—		1,500
Total	$	429,868	$	120,016	$	571,577	$	544,162	$	1,665,623
Estimated Fair Value
Residential mortgage-backed securities	$	16	$	—	$	498,078	$	11,356	$	509,450
States and political subdivisions	431,961		119,698		56,973		520,427		1,129,059
Other	—		1,484		—		—		1,484
Total	$	431,977	$	121,182	$	555,051	$	531,783	$	1,639,993
Available For Sale
Amortized Cost
U. S. Treasury	$	—	$	2,033,995	$	1,432,731	$	191,780	$	3,658,506
Residential mortgage-backed securities	102		12,917		19,060		5,664,827		5,696,906
States and political subdivisions	194,416		1,563,829		888,489		4,572,087		7,218,821
Other	—		—		—		—		42,361
Total	$	194,518	$	3,610,741	$	2,340,280	$	10,428,694	$	16,616,594
Estimated Fair Value
U. S. Treasury	$	—	$	1,978,865	$	1,350,553	$	178,328	$	3,507,746
Residential mortgage-backed securities	103		13,212		19,327		5,343,397		5,376,039
States and political subdivisions	197,231		1,603,985		899,602		4,557,575		7,258,393
Other	—		—		—		—		42,361
Total	$	197,334	$	3,596,062	$	2,269,482	$	10,079,300	$	16,184,539

Sales of Securities. No held to maturity or available for sale securities were sold during the three months ended March 31, 2022 or 2021.

Premiums and Discounts. Premium amortization and discount accretion included in interest income on securities was as follows:

	Three Months Ended March 31,
	2022		2021
Premium amortization	$	(29,060)	$	(31,235)
Discount accretion	1,406		637
Net (premium amortization) discount accretion	$	(27,654)	$	(30,598)

Trading Account Securities. Trading account securities, at estimated fair value, were as follows:

	March 31, 2022		December 31, 2021
U.S. Treasury	$	23,939	$	24,237
States and political subdivisions	5,579		925
Total	$	29,518	$	25,162

11

Net gains and losses on trading account securities were as follows:

	Three Months Ended March 31,
	2022		2021
Net gain on sales transactions	$	340	$	109
Net mark-to-market gains (losses)	(168)		(69)
Net gain (loss) on trading account securities	$	172	$	40

Note 3 - Loans

Loans were as follows:

	March 31, 2022		December 31, 2021
Commercial and industrial	$	5,584,117	$	5,364,954
Energy:
Production	820,107		878,436
Service	113,708		105,901
Other	102,764		93,455
Total energy	1,036,579		1,077,792
Paycheck Protection Program	207,669		428,882
Commercial real estate:
Commercial mortgages	5,918,011		5,867,062
Construction	1,421,878		1,304,271
Land	458,510		405,277
Total commercial real estate	7,798,399		7,576,610
Consumer real estate:
Home equity loans	321,842		324,157
Home equity lines of credit	544,822		519,098
Other	566,961		567,535
Total consumer real estate	1,433,625		1,410,790
Total real estate	9,232,024		8,987,400
Consumer and other	482,148		477,369
Total loans	$	16,542,537	$	16,336,397

Concentrations of Credit. Most of our lending activity occurs within the State of Texas, including the four largest metropolitan areas of Austin, Dallas/Ft. Worth, Houston and San Antonio, as well as other markets. The majority of our loan portfolio consists of commercial and industrial and commercial real estate loans. As of March 31, 2022, there were no concentrations of loans related to any single industry in excess of 10% of total loans. The largest industry concentration was related to the energy industry, which totaled 6.3% of total loans (also 6.3% excluding PPP loans). Unfunded commitments to extend credit and standby letters of credit issued to customers in the energy industry totaled $862.2 million and $76.0 million, respectively, as of March 31, 2022.

Foreign Loans. We have U.S. dollar denominated loans and commitments to borrowers in Mexico. The outstanding balance of these loans and the unfunded amounts available under these commitments were not significant at March 31, 2022 or December 31, 2021.

Related Party Loans. In the ordinary course of business, we have granted loans to certain directors, executive officers and their affiliates (collectively referred to as “related parties”). Such loans totaled $346.5 million at March 31, 2022 and $350.5 million at December 31, 2021.

Accrued Interest Receivable. Accrued interest receivable on loans totaled $39.5 million and $40.0 million at March 31, 2022 and December 31, 2021, respectively and is included in accrued interest receivable and other assets in the accompany consolidated balance sheets.

12

Non-Accrual and Past Due Loans. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Loans are placed on non-accrual status when, in management’s opinion, the borrower may be unable to meet payment obligations as they become due, as well as when required by regulatory provisions.

Non-accrual loans, segregated by class of loans, were as follows:

	March 31, 2022				December 31, 2021
	Total Non-Accrual		Non-Accrual with No Credit Loss Allowance		Total Non-Accrual		Non-Accrual with No Credit Loss Allowance
Commercial and industrial	$	16,693	$	6,135	$	22,582	$	4,701
Energy	12,271		6,912		14,433		8,533
Paycheck Protection Program	—		—		—		—
Commercial real estate:
Buildings, land and other	19,003		17,005		15,297		13,817
Construction	583		583		948		—
Consumer real estate	416		114		440		138
Consumer and other	—		—		13		13
Total	$	48,966	$	30,749	$	53,713	$	27,202

The following table presents non-accrual loans as of March 31, 2022 by class and year of origination.

	2021		2020		2019		2018		2017		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Commercial and industrial	$	—	$	478	$	4,101	$	3,910	$	1,552	$	1,033	$	2,038	$	3,581	$	16,693
Energy	—		—		—		5,039		1,137		—		5,997		98		12,271
Paycheck Protection Program	—		—		—		—		—		—		—		—		—
Commercial real estate:
Buildings, land and other	—		8,407		296		1,199		394		2,932		—		5,775		19,003
Construction	—		—		583		—		—		—		—		—		583
Consumer real estate	—		—		—		—		—		390		—		26		416
Consumer and other	—		—		—		—		—		—		—		—		—
Total	$	—	$	8,885	$	4,980	$	10,148	$	3,083	$	4,355	$	8,035	$	9,480	$	48,966

Had non-accrual loans performed in accordance with their original contract terms, we would have recognized additional interest income, net of tax, of approximately $407 thousand for the three months ended March 31, 2022, and approximately $453 thousand for the three months ended March 31, 2021.

An age analysis of past due loans (including both accruing and non-accruing loans), segregated by class of loans, as of March 31, 2022 was as follows:

	Loans 30-89 Days Past Due		Loans 90 or More Days Past Due		Total Past Due Loans		Current Loans		Total Loans		Accruing Loans 90 or More Days Past Due
Commercial and industrial	$	13,016	$	8,042	$	21,058	$	5,563,059	$	5,584,117	$	4,166
Energy	—		6,382		6,382		1,030,197		1,036,579		287
Paycheck Protection Program	671		8,377		9,048		198,621		207,669		8,377
Commercial real estate:
Buildings, land and other	21,542		11,546		33,088		6,343,433		6,376,521		1,046
Construction	1,988		—		1,988		1,419,890		1,421,878		—
Consumer real estate	4,210		2,409		6,619		1,427,006		1,433,625		2,103
Consumer and other	6,393		593		6,986		475,162		482,148		593
Total	$	47,820	$	37,349	$	85,169	$	16,457,368	$	16,542,537	$	16,572

13

Troubled Debt Restructurings. There were no loans modified as troubled debt restructurings during the three months ended March 31, 2022 and 2021. Loan modifications are typically related to extending amortization periods, converting loans to interest only for a limited period of time, deferral of interest payments, waiver of certain covenants, consolidating notes and/or reducing collateral or interest rates. Modifications have not generally had a significant impact on our determination of the allowance for credit losses on loans. Information as of or for the three months ended March 31, 2022 and 2021 related to loans restructured during the last twelve months is set forth in the following table.

	March 31, 2022		March 31, 2021
Restructured loans past due in excess of 90 days at period-end:
Number of loans	2		2
Dollar amount of loans	$	572	$	1,392
Charge-offs of restructured loans:
Recognized on previously restructured loans	723		1,433

Credit Quality Indicators. As part of the on-going monitoring of the credit quality of our loan portfolio, management tracks certain credit quality indicators including trends related to (i) the weighted-average risk grade of commercial loans, (ii) the level of classified commercial loans, (iii) the delinquency status of consumer loans (iv) non-performing loans (see details above) and (vi) the general economic conditions in the State of Texas.

We utilize a risk grading matrix to assign a risk grade to each of our commercial loans. Loans are graded on a scale of 1 to 14. A description of the general characteristics of the 14 risk grades is set forth in our 2021 Form 10-K. We monitor portfolio credit quality by the weighted-average risk grade of each class of commercial loan. Individual relationship managers, under the oversight of credit administration, review updated financial information for all pass grade loans to reassess the risk grade on at least an annual basis. When a loan has a risk grade of 9, it is still considered a pass grade loan; however, it is considered to be on management’s “watch list,” where a significant risk-modifying action is anticipated in the near term. When a loan has a risk grade of 10 or higher, a special assets officer monitors the loan on an on-going basis.

The following tables present weighted-average risk grades for all commercial loans, by class and year of origination/renewal as of March 31, 2022. Paycheck Protection Program (“PPP”) loans are excluded as such loans are fully guaranteed by the Small Business Administration (“SBA”).

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial and industrial
Risk grades 1-8	$	836,152	$	894,663	$	592,780	$	305,667	$	160,622	$	243,869	$	2,255,878	$	44,778	$	5,334,409	6.18
Risk grade 9	4,702		34,513		6,562		11,434		21,841		8,319		54,008		4,721		146,100		9.00
Risk grade 10	3,500		22,084		6,527		1,039		4,007		578		13,899		1,198		52,832		10.00
Risk grade 11	—		1,926		6,672		9,679		1,697		2,200		5,958		5,951		34,083		11.00
Risk grade 12	—		478		2,644		3,510		1,488		619		941		2,015		11,695		12.00
Risk grade 13	—		—		1,457		400		64		414		1,097		1,566		4,998		13.00
	$	844,354	$	953,664	$	616,642	$	331,729	$	189,719	$	255,999	$	2,331,781	$	60,229	$	5,584,117	6.34
W/A risk grade	6.16		6.87		6.17		6.75		7.00		5.80		6.14		7.82		6.34
Energy
Risk grades 1-8	$	279,051	$	125,435	$	7,519	$	8,444	$	4,068	$	5,665	$	509,657	$	59,424	$	999,263	5.71
Risk grade 9	1,425		103		508		1,407		96		—		5,668		43		9,250		9.00
Risk grade 10	—		—		90		580		351		—		—		515		1,536		10.00
Risk grade 11	9,097		265		512		3,256		951		178		—		—		14,259		11.00
Risk grade 12	—		—		—		3,708		58		—		3,215		98		7,079		12.00
Risk grade 13	—		—		—		1,331		1,079		—		2,782		—		5,192		13.00
	$	289,573	$	125,803	$	8,629	$	18,726	$	6,603	$	5,843	$	521,322	$	60,080	$	1,036,579	5.89
W/A risk grade	6.36		5.77		7.73		9.34		9.24		7.16		5.41		6.31		5.89

14

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial real estate:
Buildings, land, other
Risk grades 1-8	$	607,883	$	1,554,611	$	1,113,230	$	809,206	$	498,477	$	1,057,840	$	72,704	$	96,924	$	5,810,875	6.89
Risk grade 9	6,163		20,766		108,943		53,448		23,459		45,034		5,516		2,618		265,947		9.00
Risk grade 10	46,125		22,716		7,310		66,821		24,539		57,602		—		—		225,113		10.00
Risk grade 11	—		260		1,293		7,328		6,788		36,699		3,215		—		55,583		11.00
Risk grade 12	—		8,081		296		1,199		394		2,932		—		5,775		18,677		12.00
Risk grade 13	—		326		—		—		—		—		—		—		326		13.00
	$	660,171	$	1,606,760	$	1,231,072	$	938,002	$	553,657	$	1,200,107	$	81,435	$	105,317	$	6,376,521	7.14
W/A risk grade	7.08		7.22		7.04		7.32		7.27		6.97		7.06		6.99		7.14
Construction
Risk grades 1-8	$	202,413	$	634,897	$	195,127	$	141,510	$	636	$	1,842	$	207,182	$	3,666	$	1,387,273	6.96
Risk grade 9	171		28,069		5,359		—		—		423		—		—		34,022		9.00
Risk grade 10	—		—		—		—		—		—		—		—		—		10.00
Risk grade 11	—		—		—		—		—		—		—		—		—		11.00
Risk grade 12	—		—		583		—		—		—		—		—		583		12.00
Risk grade 13	—		—		—		—		—		—		—		—		—		13.00
	$	202,584	$	662,966	$	201,069	$	141,510	$	636	$	2,265	$	207,182	$	3,666	$	1,421,878	7.01
W/A risk grade	6.83		7.28		6.38		7.98		6.22		7.17		6.28		8.00		7.01
Total commercial real estate	$	862,755	$	2,269,726	$	1,432,141	$	1,079,512	$	554,293	$	1,202,372	$	288,617	$	108,983	$	7,798,399	7.11
W/A risk grade	7.02		7.24		6.95		7.41		7.27		6.97		6.50		7.03		7.11

In the table above, certain energy loans are reported as 2022 originations and have risk grades of 11 or higher. These loans were, for the most part, first originated in various years prior to 2022 but were renewed in the current year.

The following tables present weighted average risk grades for all commercial loans by class as of December 31, 2021. Refer to our 2021 Form 10-K for details of these loans by year of origination/renewal.

	Commercial and Industrial			Energy			Commercial Real Estate - Buildings, Land and Other			Commercial Real Estate - Construction			Total Commercial Real Estate
	W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans
Risk grades 1-8	6.01	$	5,063,847	5.78	$	1,008,370	6.91	$	5,574,922	6.99	$	1,262,200	6.92	$	6,837,122
Risk grade 9	9.00	187,870		9.00	36,622		9.00	321,533		9.00	41,123		9.00	362,656
Risk grade 10	10.00	59,137		10.00	1,773		10.00	269,447		10.00	—		10.00	269,447
Risk grade 11	11.00	31,518		11.00	16,594		11.00	91,140		11.00	—		11.00	91,140
Risk grade 12	12.00	12,535		12.00	8,953		12.00	15,097		12.00	748		12.00	15,845
Risk grade 13	13.00	10,047		13.00	5,480		13.00	200		13.00	200		13.00	400
Total	6.22	$	5,364,954	6.06	$	1,077,792	7.22	$	6,272,339	7.06	$	1,304,271	7.19	$	7,576,610

15

Information about the payment status of consumer loans, segregated by portfolio segment and year of origination, as of March 31, 2022 was as follows:

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Consumer real estate:
Past due 30-89 days	$	—	$	303	$	55	$	465	$	309	$	1,587	$	60	$	1,431	$	4,210
Past due 90 or more days	—		—		4		—		297		854		1,004		250		2,409
Total past due	—		303		59		465		606		2,441		1,064		1,681		6,619
Current loans	51,321		322,814		225,921		86,664		48,481		149,677		533,182		8,946		1,427,006
Total	$	51,321	$	323,117	$	225,980	$	87,129	$	49,087	$	152,118	$	534,246	$	10,627	$	1,433,625
Consumer and other:
Past due 30-89 days	$	1,470	$	385	$	53	$	69	$	54	$	24	$	2,344	$	1,994	$	6,393
Past due 90 or more days	—		499		—		23		—		13		—		58		593
Total past due	1,470		884		53		92		54		37		2,344		2,052		6,986
Current loans	21,692		34,798		13,127		4,936		2,207		2,520		371,266		24,616		475,162
Total	$	23,162	$	35,682	$	13,180	$	5,028	$	2,261	$	2,557	$	373,610	$	26,668	$	482,148

Revolving loans that converted to term during the three months ended March 31, 2022 and 2021 were as follows:

	Three Months Ended March 31,
	2021		2020
Commercial and industrial	$	5,763	$	11,843
Energy	—		5,928
Commercial real estate:
Buildings, land and other	47		23,303
Construction	3,666		—
Consumer real estate	858		793
Consumer and other	4,222		3,861
Total	$	14,556	$	45,728

In assessing the general economic conditions in the State of Texas, management monitors and tracks the Texas Leading Index (“TLI”), which is produced by the Federal Reserve Bank of Dallas. The TLI, the components of which are more fully described in our 2021 Form 10-K, totaled 141.2 at March 31, 2022 and 135.9 at December 31, 2021. A higher TLI value implies more favorable economic conditions.

Allowance For Credit Losses - Loans. The allowance for credit losses on loans is a contra-asset valuation account, calculated in accordance with ASC 326, that is deducted from the amortized cost basis of loans to present the net amount expected to be collected. The amount of the allowance represents management's best estimate of current expected credit losses on loans considering available information, from internal and external sources, relevant to assessing collectibility over the loans' contractual terms, adjusted for expected prepayments when appropriate. Credit loss expense related to loans reflects the totality of actions taken on all loans for a particular period including any necessary increases or decreases in the allowance related to changes in credit loss expectations associated with specific loans or pools of loans. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged off. While management utilizes its best judgment and information available, the ultimate appropriateness of the allowance is dependent upon a variety of factors beyond our control, including the performance of our loan portfolio, the economy, changes in interest rates and the view of the regulatory authorities toward loan classifications. Our allowance methodology is more fully described in our 2021 Form 10-K.

16

The following table presents details of the allowance for credit losses on loans segregated by loan portfolio segment as of March 31, 2022 and December 31, 2021. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA.

March 31, 2022	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Modeled expected credit losses	$	46,635	$	5,971	$	17,110	$	6,260	$	7,634	$	83,610
Q-Factor and other qualitative adjustments	33,916		4,260		111,518		63		1,440		151,197
Specific allocations	6,475		5,191		326		36		—		12,028
Total	$	87,026	$	15,422	$	128,954	$	6,359	$	9,074	$	246,835
December 31, 2021
Modeled expected credit losses	$	46,946	$	6,363	$	16,676	$	6,484	$	6,397	$	82,866
Q-Factor and other qualitative adjustments	14,609		5,374		127,860		65		1,440		149,348
Specific allocations	10,536		5,480		400		36		—		16,452
Total	$	72,091	$	17,217	$	144,936	$	6,585	$	7,837	$	248,666

The following table details activity in the allowance for credit losses on loans by portfolio segment for the three months ended March 31, 2022 and 2021. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA.

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Three months ended:
March 31, 2022
Beginning balance	$	72,091	$	17,217	$	144,936	$	6,585	$	7,837	$	248,666
Credit loss expense (benefit)	17,561		(2,044)		(15,609)		(26)		4,582		4,464
Charge-offs	(3,455)		(371)		(702)		(231)		(5,771)		(10,530)
Recoveries	829		620		329		31		2,426		4,235
Net charge-offs	(2,626)		249		(373)		(200)		(3,345)		(6,295)
Ending balance	$	87,026	$	15,422	$	128,954	$	6,359	$	9,074	$	246,835
March 31, 2021
Beginning balance	$	73,843	$	39,553	$	134,892	$	7,926	$	6,963	$	263,177
Credit loss expense (benefit)	(1,965)		(5,801)		8,922		(2,722)		1,566		—
Charge-offs	(2,189)		(1,433)		—		(284)		(4,060)		(7,966)
Recoveries	1,203		1,153		626		716		2,349		6,047
Net charge-offs	(986)		(280)		626		432		(1,711)		(1,919)
Ending balance	$	70,892	$	33,472	$	144,440	$	5,636	$	6,818	$	261,258

The following table presents loans that were evaluated for expected credit losses on an individual basis and the related specific allocations, by loan portfolio segment as of March 31, 2022 and December 31, 2021.

	March 31, 2022				December 31, 2021
	Loan Balance		Specific Allocations		Loan Balance		Specific Allocations
Commercial and industrial	$	21,529	$	6,475	$	24,523	$	10,536
Energy	11,931		5,191		16,393		5,480
Paycheck Protection Program	—		—		—		—
Commercial real estate:
Buildings, land and other	28,806		326		24,670		200
Construction	—		—		948		200
Consumer real estate	302		36		303		36
Consumer and other	—		—		—		—
Total	$	62,568	$	12,028	$	66,837	$	16,452

17

Note 4 - Goodwill and Other Intangible Assets

Goodwill and other intangible assets are presented in the table below.

	March 31, 2022		December 31, 2021
Goodwill	$	654,952	$	654,952
Other intangible assets:
Core deposits	$	591	$	718
Customer relationships	129		148
	$	720	$	866

The estimated aggregate future amortization expense for intangible assets remaining as of March 31, 2022 is as follows:

Remainder of 2022	$	335
2023	282
2024	87
2025	11
2026	5
Thereafter	—
	$	720

Note 5 - Deposits

Deposits were as follows:

	March 31, 2022		December 31, 2021
Non-interest-bearing demand deposits	$	18,114,430	$	18,423,018
Interest-bearing deposits:
Savings and interest checking	12,484,308		11,930,959
Money market accounts	12,490,612		11,228,815
Time accounts	1,341,579		1,112,904
Total interest-bearing deposits	26,316,499		24,272,678
Total deposits	$	44,430,929	$	42,695,696

The following table presents additional information about our deposits:

	March 31, 2022		December 31, 2021
Deposits from foreign sources (primarily Mexico)	$	1,092,302	$	993,479
Non-interest-bearing public funds deposits	746,097		1,235,026
Interest-bearing public funds deposits	975,511		810,863
Total deposits not covered by deposit insurance	25,213,248		24,125,359
Time deposits not covered by deposit insurance	357,529		238,608

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Note 6 - Off-Balance-Sheet Arrangements, Commitments, Guarantees and Contingencies

Financial Instruments with Off-Balance-Sheet Risk. In the normal course of business, we enter into various transactions, which, in accordance with generally accepted accounting principles are not included in our consolidated balance sheets. We enter into these transactions to meet the financing needs of our customers. As more fully discussed in our 2021 Form 10-K, these transactions include commitments to extend credit and standby letters of credit, which involve, to varying degrees, elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets. We minimize our exposure to loss under these commitments by subjecting them to credit approval and monitoring procedures.

Financial instruments with off-balance-sheet risk were as follows:

	March 31, 2022		December 31, 2021
Commitments to extend credit	$	10,356,196	$	10,420,142
Standby letters of credit	236,798		238,690
Deferred standby letter of credit fees	1,704		2,072

Allowance For Credit Losses - Off-Balance-Sheet Credit Exposures. The allowance for credit losses on off-balance-sheet credit exposures is a liability account, calculated in accordance with ASC 326, representing expected credit losses over the contractual period for which we are exposed to credit risk resulting from a contractual obligation to extend credit. No allowance is recognized if we have the unconditional right to cancel the obligation. Off-balance-sheet credit exposures primarily consist of amounts available under outstanding lines of credit and letters of credit detailed in the table above. The amount of the allowance represents management's best estimate of expected credit losses on commitments expected to be funded over the contractual life of the commitment. Our allowance methodology is more fully described in our 2021 Form 10-K.

The following table details activity in the allowance for credit losses on off-balance-sheet credit exposures.

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	50,314	$	44,152
Credit loss expense (benefit)	(4,464)		65
Ending balance	$	45,850	$	44,217

Lease Commitments. We lease certain office facilities and office equipment under operating leases. The components of total lease expense were as follows:

	Three Months Ended March 31,
	2022		2021
Amortization of lease right-of-use assets	$	8,105	$	8,283
Short-term lease expense	613		204
Non-lease components (including taxes, insurance, common maintenance, etc.)	3,020		3,004
Total	$	11,738	$	11,491

Right-of-use lease assets totaled $279.5 million at March 31, 2022 and $281.4 million at December 31, 2021 and are reported as a component of premises and equipment on our accompanying consolidated balance sheets. The related lease liabilities totaled $311.8 million at March 31, 2022 and $313.4 million at December 31, 2021 and are reported as a component of accrued interest payable and other liabilities in the accompanying consolidated balance sheets. Lease payments under operating leases that were applied to our operating lease liability totaled $8.0 million during the three months ended March 31, 2022 and $8.1 million during the three months ended March 31, 2021. There has been no significant change in our expected future minimum lease payments since December 31, 2021. See the 2021 Form 10-K for information regarding these commitments.

Litigation. We are subject to various claims and legal actions that have arisen in the course of conducting business. Management does not expect the ultimate disposition of these matters to have a material adverse impact on our financial statements.

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Note 7 - Capital and Regulatory Matters

Banks and bank holding companies are subject to various regulatory capital requirements administered by state and federal banking agencies. Capital adequacy guidelines and, additionally for banks, prompt corrective action regulations, involve quantitative measures of assets, liabilities, and certain off-balance-sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgments by regulators about components, risk weighting and other factors.

Cullen/Frost’s and Frost Bank’s Common Equity Tier 1 capital (“CET1”) includes common stock and related paid-in capital, net of treasury stock, and retained earnings. In connection with the adoption of the Basel III Capital Rules, we elected to opt-out of the requirement to include most components of accumulated other comprehensive income in CET1. We also elected to exclude the effects of credit loss accounting under CECL from CET1 for a five-year transitional period, as further discussed in our 2021 Form 10-K. This CECL transitional adjustment totaled $46.2 million and $61.6 million at March 31, 2022 and December 31, 2021, respectively. CET1 is reduced by goodwill and other intangible assets, net of associated deferred tax liabilities. Frost Bank's CET1 is also reduced by its equity investment in its financial subsidiary, Frost Insurance Agency (“FIA”).

Tier 1 capital includes CET1 and additional Tier 1 capital. For Cullen/Frost, additional Tier 1 capital included $145.5 million of 4.450% non-cumulative perpetual preferred stock at March 31, 2022 and December 31, 2021, the details of which are further discussed below. Frost Bank did not have any additional Tier 1 capital beyond Common Equity Tier 1 at March 31, 2022 or December 31, 2021. Total capital includes Tier 1 capital and Tier 2 capital. Tier 2 capital for both Cullen/Frost and Frost Bank includes a permissible portion of the allowances for credit losses on securities, loans and off-balance-sheet credit exposures. Tier 2 capital for Cullen/Frost also includes the permissible portion of qualified subordinated debt (which decreases 20.0% per year during the final five years of the term of the notes) totaling $80.0 million at March 31, 2022 and $100.0 million at December 31, 2021 and trust preferred securities totaling $120.0 million at both March 31, 2022 and December 31, 2021.

The following table presents actual and required capital ratios as of March 31, 2022 and December 31, 2021 for Cullen/Frost and Frost Bank under the Basel III Capital Rules. Capital levels required to be considered well capitalized are based upon prompt corrective action regulations, as amended to reflect the changes under the Basel III Capital Rules. See the 2021 Form 10-K for a more detailed discussion of the Basel III Capital Rules.

	Actual				Minimum Capital Required - Basel III				Required to be Considered Well Capitalized
	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
March 31, 2022
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,412,080	12.78	%	$	1,869,007	7.00	%	$	1,735,506	6.50	%
Frost Bank	3,301,515		12.39		1,865,304		7.00		1,732,068		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,557,532		13.32		2,269,508		8.50		2,136,007		8.00
Frost Bank	3,301,515		12.39		2,265,012		8.50		2,131,776		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,998,333		14.97		2,803,510		10.50		2,670,009		10.00
Frost Bank	3,542,316		13.29		2,797,956		10.50		2,664,720		10.00
Leverage Ratio
Cullen/Frost	3,557,532		7.08		2,010,897		4.00		2,513,621		5.00
Frost Bank	3,301,515		6.57		2,009,767		4.00		2,512,209		5.00
December 31, 2021
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,371,043	13.13	%	$	1,796,549	7.00	%	$	1,668,224	6.50	%
Frost Bank	3,261,532		12.72		1,795,221		7.00		1,666,991		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,516,495		13.70		2,181,523		8.50		2,053,198		8.00
Frost Bank	3,261,532		12.72		2,179,911		8.50		2,051,681		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,966,244		15.45		2,694,823		10.50		2,566,498		10.00
Frost Bank	3,491,281		13.61		2,692,831		10.50		2,564,601		10.00
Leverage Ratio
Cullen/Frost	3,516,495		7.34		1,917,533		4.00		2,396,917		5.00
Frost Bank	3,261,532		6.80		1,917,679		4.00		2,397,099		5.00

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As of March 31, 2022, capital levels at Cullen/Frost and Frost Bank exceed all capital adequacy requirements under the Basel III Capital Rules. Based on the ratios presented above, capital levels as of March 31, 2022 at Cullen/Frost and Frost Bank exceed the minimum levels necessary to be considered “well capitalized.”

Cullen/Frost and Frost Bank are subject to the regulatory capital requirements administered by the Federal Reserve Board and, for Frost Bank, the Federal Deposit Insurance Corporation (“FDIC”). Regulatory authorities can initiate certain mandatory actions if Cullen/Frost or Frost Bank fail to meet the minimum capital requirements, which could have a direct material effect on our financial statements. Management believes, as of March 31, 2022, that Cullen/Frost and Frost Bank meet all capital adequacy requirements to which they are subject.

Preferred Stock. Outstanding preferred stock includes 150,000 shares, or $150.0 million in aggregate liquidation preference, of our 4.450% Non-Cumulative Perpetual Preferred Stock, Series B, par value $0.01 and liquidation preference $1,000 per share (“Series B Preferred Stock”). Each share of Series B Preferred Stock issued and outstanding is represented by 40 depositary shares, each representing a 1/40th ownership interest in a share of the Series B Preferred Stock (equivalent to a liquidation preference of $25 per share). The Series B Preferred Stock qualifies as Tier 1 capital for the purposes of the regulatory capital calculations. The net proceeds from the issuance and sale of the Series B Preferred Stock, after deducting $4.5 million of issuance costs including the underwriting discount and professional service fees, among other things, were approximately $145.5 million. Refer to our 2021 Form 10-K for additional details related to our Series B Preferred Stock.

Stock Repurchase Plans. From time to time, our board of directors has authorized stock repurchase plans. In general, stock repurchase plans allow us to proactively manage our capital position and return excess capital to shareholders. Shares purchased under such plans also provide us with shares of common stock necessary to satisfy obligations related to stock compensation awards. On January 26, 2022, our board of directors authorized a $100.0 million stock repurchase program, allowing us to repurchase shares of our common stock over a one-year period from time to time at various prices in the open market or through private transactions. No shares have been repurchased under this plan or the prior plan during the reported periods. Under the Basel III Capital Rules, Cullen/Frost may not repurchase or redeem any of its subordinated notes and, in some cases, its common stock without the prior approval of the Federal Reserve Board.

Dividend Restrictions. In the ordinary course of business, Cullen/Frost is dependent upon dividends from Frost Bank to provide funds for the payment of dividends to shareholders and to provide for other cash requirements, including to repurchase its common stock. Banking regulations may limit the amount of dividends that may be paid. Approval by regulatory authorities is required if the effect of dividends declared would cause the regulatory capital of Frost Bank to fall below specified minimum levels. Approval is also required if dividends declared exceed the net profits for that year combined with the retained net profits for the preceding two years. Under the foregoing dividend restrictions and while maintaining its “well capitalized” status, at March 31, 2022, Frost Bank could pay aggregate dividends of up to $325.0 million to Cullen/Frost without prior regulatory approval.

Under the terms of the junior subordinated deferrable interest debentures that Cullen/Frost has issued to Cullen/Frost Capital Trust II, Cullen/Frost has the right at any time during the term of the debentures to defer the payment of interest at any time or from time to time for an extension period not exceeding 20 consecutive quarterly periods with respect to each extension period. In the event that we have elected to defer interest on the debentures, we may not, with certain exceptions, declare or pay any dividends or distributions on our capital stock or purchase or acquire any of our capital stock.

Note 8 - Derivative Financial Instruments

The fair value of derivative positions outstanding is included in accrued interest receivable and other assets and accrued interest payable and other liabilities in the accompanying consolidated balance sheets and in the net change in each of these financial statement line items in the accompanying consolidated statements of cash flows.

Interest Rate Derivatives. We utilize interest rate swaps, caps, swaptions and floors to mitigate exposure to interest rate risk and to facilitate the needs of our customers. Our objectives for utilizing these derivative instruments are described in our 2021 Form 10-K.

The notional amounts and estimated fair values of interest rate derivative contracts are presented in the following table. The fair values of interest rate derivative contracts are estimated utilizing internal valuation methods with observable market data inputs, or as determined by the Chicago Mercantile Exchange (“CME”) for centrally cleared derivative contracts. CME rules legally characterize variation margin payments for centrally cleared derivatives as settlements of the derivatives' exposure rather than collateral. As a result, the variation margin payment and the related derivative instruments are considered a single unit of account for accounting and financial reporting purposes. Variation margin, as determined by the CME, is settled daily. As a result, derivative contracts that clear through the CME have an estimated fair value of zero as of March 31, 2022 and December 31, 2021.

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	March 31, 2022				December 31, 2021
	Notional Amount		Estimated Fair Value		Notional Amount		Estimated Fair Value
Derivatives designated as hedges of fair value:
Financial institution counterparties:
Loan/lease interest rate swaps – assets	$	1,807	$	1	$	—	$	—
Loan/lease interest rate swaps – liabilities	280		(3)		2,426		(34)
Non-hedging interest rate derivatives:
Financial institution counterparties:
Loan/lease interest rate swaps – assets	697,834		15,311		247,592		1,207
Loan/lease interest rate swaps – liabilities	447,742		(6,184)		928,756		(19,142)
Loan/lease interest rate caps – assets	265,930		8,110		270,431		3,239
Customer counterparties:
Loan/lease interest rate swaps – assets	447,742		10,275		928,756		39,864
Loan/lease interest rate swaps – liabilities	697,834		(25,437)		247,592		(2,846)
Loan/lease interest rate caps – liabilities	265,930		(8,110)		270,431		(3,239)

The weighted-average rates paid and received for interest rate swaps outstanding at March 31, 2022 were as follows:

	Weighted-Average
	Interest Rate Paid		Interest Rate Received
Interest rate swaps:
Fair value hedge loan/lease interest rate swaps	2.11	%	0.26	%
Non-hedging interest rate swaps – financial institution counterparties	3.69		2.07
Non-hedging interest rate swaps – customer counterparties	2.07		3.69

The weighted-average strike rate for outstanding interest rate caps was 3.27% at March 31, 2022.

Commodity Derivatives. We enter into commodity swaps and option contracts that are not designated as hedging instruments primarily to accommodate the business needs of our customers. Upon the origination of a commodity swap or option contract with a customer, we simultaneously enter into an offsetting contract with a third party financial institution to mitigate the exposure to fluctuations in commodity prices.

The notional amounts and estimated fair values of non-hedging commodity swap and option derivative positions outstanding are presented in the following table. We obtain dealer quotations and use internal valuation methods with observable market data inputs to value our commodity derivative positions.

		March 31, 2022			December 31, 2021
	Notional Units	Notional Amount	Estimated Fair Value		Notional Amount	Estimated Fair Value
Financial institution counterparties:
Oil – assets	Barrels	2,988	$	9,735	4,809	$	14,721
Oil – liabilities	Barrels	9,767	(189,416)		7,032	(73,594)
Natural gas – assets	MMBTUs	14,564	1,813		15,947	4,143
Natural gas – liabilities	MMBTUs	27,474	(50,244)		29,446	(21,249)
Customer counterparties:
Oil – assets	Barrels	9,767	190,776		7,046	74,437
Oil – liabilities	Barrels	2,988	(9,710)		4,796	(14,294)
Natural gas – assets	MMBTUs	27,474	50,423		29,446	21,456
Natural gas – liabilities	MMBTUs	14,564	(1,811)		15,947	(4,124)

Foreign Currency Derivatives. We enter into foreign currency forward contracts that are not designated as hedging instruments primarily to accommodate the business needs of our customers. Upon the origination of a foreign currency denominated transaction with a customer, we simultaneously enter into an offsetting contract with a third party financial institution to negate the exposure to fluctuations in foreign currency exchange rates. We also utilize foreign currency forward contracts that are not designated as hedging instruments to mitigate the economic effect of fluctuations in foreign currency

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exchange rates on foreign currency holdings and certain short-term, non-U.S. dollar denominated loans. The notional amounts and fair values of open foreign currency forward contracts were as follows:

		March 31, 2022			December 31, 2021
	Notional Currency	Notional Amount	Estimated Fair Value		Notional Amount	Estimated Fair Value
Financial institution counterparties:
Forward contracts – assets	EUR	2,400	$	18	1,900	$	29
Forward contracts – assets	CAD	—	—		658	—
Forward contracts – liabilities	EUR	6,500	(111)		—	—
Forward contracts – liabilities	CAD	658	(6)		—	—
Customer counterparties:
Forward contracts – assets	EUR	6,500	122		—	—
Forward contracts – assets	CAD	658	10		658	4
Forward contracts – liabilities	EUR	2,400	(14)		1,900	(55)

Gains, Losses and Derivative Cash Flows. For fair value hedges, the changes in the fair value of both the derivative hedging instrument and the hedged item are included in other non-interest income or other non-interest expense. The extent that such changes in fair value do not offset represents hedge ineffectiveness. Net cash flows from interest rate swaps on commercial loans/leases designated as hedging instruments in effective hedges of fair value are included in interest income on loans. For non-hedging derivative instruments, gains and losses due to changes in fair value and all cash flows are included in other non-interest income and other non-interest expense.

Amounts included in the consolidated statements of income related to interest rate derivatives designated as hedges of fair value were as follows:

	Three Months Ended March 31,
	2022		2021
Commercial loan/lease interest rate swaps:
Amount of gain (loss) included in interest income on loans	$	(13)	$	(28)
Amount of (gain) loss included in other non-interest expense	2		(3)

As stated above, we enter into non-hedge related derivative positions primarily to accommodate the business needs of our customers. Upon the origination of a derivative contract with a customer, we simultaneously enter into an offsetting derivative contract with a third party financial institution. We recognize immediate income based upon the difference in the bid/ask spread of the underlying transactions with our customers and the third party. Because we act only as an intermediary for our customer, subsequent changes in the fair value of the underlying derivative contracts for the most part offset each other and do not significantly impact our results of operations.

Amounts included in the consolidated statements of income related to non-hedge related derivative instruments are presented in the table below.

	Three Months Ended March 31,
	2022		2021
Non-hedging interest rate derivatives:
Other non-interest income	$	516	$	1,587
Other non-interest expense	—		(1)
Non-hedging commodity derivatives:
Other non-interest income	929		1,154
Non-hedging foreign currency derivatives:
Other non-interest income	18		30

Counterparty Credit Risk. Our credit exposure relating to interest rate swaps, commodity swaps/options and foreign currency forward contracts with bank customers was approximately $238.4 million at March 31, 2022. This credit exposure is partly mitigated as transactions with customers are generally secured by the collateral, if any, securing the underlying transaction being hedged. Our credit exposure, net of collateral pledged, relating to interest rate swaps, commodity swaps/options and foreign currency forward contracts with upstream financial institution counterparties was approximately $35.7 million at March 31, 2022. This amount was primarily related to initial margin payments to the CME and excess collateral we

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posted to counterparties. Collateral levels for upstream financial institution counterparties are monitored and adjusted as necessary. See Note 9 – Balance Sheet Offsetting and Repurchase Agreements for additional information regarding our credit exposure with upstream financial institution counterparties. At March 31, 2022, we had $247.3 million in cash collateral related to derivative contracts on deposit with other financial institution counterparties.

Note 9 - Balance Sheet Offsetting and Repurchase Agreements

Balance Sheet Offsetting. Certain financial instruments, including resell and repurchase agreements and derivatives, may be eligible for offset in the consolidated balance sheet and/or subject to master netting arrangements or similar agreements. Our derivative transactions with upstream financial institution counterparties are generally executed under International Swaps and Derivative Association (“ISDA”) master agreements which include “right of set-off” provisions. In such cases there is generally a legally enforceable right to offset recognized amounts and there may be an intention to settle such amounts on a net basis. Nonetheless, we do not generally offset such financial instruments for financial reporting purposes.

Information about financial instruments that are eligible for offset in the consolidated balance sheet as of March 31, 2022 is presented in the following tables.

	Gross Amount Recognized		Gross Amount Offset		Net Amount Recognized
March 31, 2022
Financial assets:
Derivatives:
Loan/lease interest rate swaps and caps	$	23,422	$	—	$	23,422
Commodity swaps and options	11,548		—		11,548
Foreign currency forward contracts	18		—		18
Total derivatives	34,988		—		34,988
Resell agreements	—		—		—
Total	$	34,988	$	—	$	34,988
Financial liabilities:
Derivatives:
Loan/lease interest rate swaps and caps	$	6,187	$	—	$	6,187
Commodity swaps and options	239,660		—		239,660
Foreign currency forward contracts	117		—		117
Total derivatives	245,964		—		245,964
Repurchase agreements	1,842,618		—		1,842,618
Total	$	2,088,582	$	—	$	2,088,582

			Gross Amounts Not Offset
	Net Amount Recognized		Financial Instruments		Collateral		Net Amount
March 31, 2022
Financial assets:
Derivatives:
Counterparty A	$	32	$	(32)	$	—	$	—
Counterparty B	11,998		(11,998)		—		—
Other counterparties	22,958		(16,251)		(6,707)		—
Total derivatives	34,988		(28,281)		(6,707)		—
Resell agreements	—		—		—		—
Total	$	34,988	$	(28,281)	$	(6,707)	$	—
Financial liabilities:
Derivatives:
Counterparty A	$	2,635	$	(32)	$	(2,603)	$	—
Counterparty B	46,953		(11,998)		(34,955)		—
Counterparty C	3		—		(3)		—
Other counterparties	196,373		(16,251)		(180,122)		—
Total derivatives	245,964		(28,281)		(217,683)		—
Repurchase agreements	1,842,618		—		(1,842,618)		—
Total	$	2,088,582	$	(28,281)	$	(2,060,301)	$	—

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Information about financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2021 is presented in the following tables.

	Gross Amount Recognized		Gross Amount Offset		Net Amount Recognized
December 31, 2021
Financial assets:
Derivatives:
Loan/lease interest rate swaps and caps	$	4,446	$	—	$	4,446
Commodity swaps and options	18,864		—		18,864
Total derivatives	23,339		—		23,339
Resell agreements	7,903		—		7,903
Total	$	31,242	$	—	$	31,242
Financial liabilities:
Derivatives:
Loan/lease interest rate swaps and caps	$	19,176	$	—	$	19,176
Commodity swaps and options	94,843		—		94,843
Total derivatives	114,019		—		114,019
Repurchase agreements	2,740,799		—		2,740,799
Total	$	2,854,818	$	—	$	2,854,818

			Gross Amounts Not Offset
	Net Amount Recognized		Financial Instruments		Collateral		Net Amount
December 31, 2021
Financial assets:
Derivatives:
Counterparty A	$	6	$	(6)	$	—	$	—
Counterparty B	7,655		(7,655)		—		—
Other counterparties	15,678		(15,678)		—		—
Total derivatives	23,339		(23,339)		—		—
Resell agreements	7,903		—		(7,903)		—
Total	$	31,242	$	(23,339)	$	(7,903)	$	—
Financial liabilities:
Derivatives:
Counterparty A	$	3,870	$	(6)	$	(3,864)	$	—
Counterparty B	28,130		(7,655)		(20,475)		—
Counterparty C	9		—		(9)		—
Other counterparties	82,010		(15,678)		(66,225)		107
Total derivatives	114,019		(23,339)		(90,573)		107
Repurchase agreements	2,740,799		—		(2,740,799)		—
Total	$	2,854,818	$	(23,339)	$	(2,831,372)	$	107

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Repurchase Agreements. We utilize securities sold under agreements to repurchase to facilitate the needs of our customers and to facilitate secured short-term funding needs. Securities sold under agreements to repurchase are stated at the amount of cash received in connection with the transaction. We monitor collateral levels on a continuous basis. We may be required to provide additional collateral based on the fair value of the underlying securities. Securities pledged as collateral under repurchase agreements are maintained with our safekeeping agents.

The remaining contractual maturity of repurchase agreements in the consolidated balance sheets as of March 31, 2022 and December 31, 2021 is presented in the following tables.

	Remaining Contractual Maturity of the Agreements
	Overnight and Continuous		Up to 30 Days		30-90 Days		Greater than 90 Days		Total
March 31, 2022
Repurchase agreements:
U.S. Treasury	$	876,879	$	—	$	—	$	—	$	876,879
Residential mortgage-backed securities	965,739		—		—		—		965,739
Total borrowings	$	1,842,618	$	—	$	—	$	—	$	1,842,618
Gross amount of recognized liabilities for repurchase agreements									$	1,842,618
Amounts related to agreements not included in offsetting disclosures above									$	—
December 31, 2021
Repurchase agreements:
U.S. Treasury	$	1,342,591	$	—	$	—	$	—	$	1,342,591
Residential mortgage-backed securities	1,398,208		—		—		—		1,398,208
Total borrowings	$	2,740,799	$	—	$	—	$	—	$	2,740,799
Gross amount of recognized liabilities for repurchase agreements									$	2,740,799
Amounts related to agreements not included in offsetting disclosures above									$	—

Note 10 - Stock-Based Compensation

A combined summary of activity in our active stock plans is presented in the table below. Performance stock units outstanding are presented assuming attainment of the maximum payout rate as set forth by the performance criteria. As of March 31, 2022, there were 794,493 shares remaining available for grant for future stock-based compensation awards.

	Deferred Stock Units Outstanding			Non-Vested Stock Units Outstanding			Performance Stock Units Outstanding			Stock Options Outstanding
	Number of Units	Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant		Number of Shares	Weighted- Average Exercise Price
Balance, January 1, 2022	56,301	$	79.21	449,337	$	93.05	202,460	$	84.71	877,681	$	69.02
Authorized	—	—		—	—		—	—		—	—
Granted	—	—		1,038	145.32		—	—		—	—
Exercised/vested	—	—		—	—		(25,180)	87.18		(90,250)	63.59
Forfeited/expired	—	—		(1,786)	89.50		(16,058)	87.18		—	—
Balance, March 31, 2022	56,301	79.21		448,589	93.19		161,222	84.08		787,431	69.64

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Shares issued in connection with stock compensation awards are issued from available treasury shares. If no treasury shares are available, new shares are issued from available authorized shares. Shares issued in connection with stock compensation awards along with other related information were as follows:

	Three Months Ended March 31,
	2022		2021
New shares issued from available authorized shares	—		—
Shares issued from available treasury stock	115,430		513,824
Proceeds from stock option exercises	$	5,739	$	29,397

Stock-based compensation expense is recognized ratably over the requisite service period for all awards. For most stock option awards, the service period generally matches the vesting period. For stock options granted to certain executive officers and for non-vested stock units granted to all participants, the service period does not extend past the date the participant reaches 65 years of age. Deferred stock units granted to non-employee directors generally have immediate vesting and the related expense is fully recognized on the date of grant. For performance stock units, the service period generally matches the three-year performance period specified by the award, however, the service period does not extend past the date the participant reaches 65 years of age. Expense recognized each period is dependent upon our estimate of the number of shares that will ultimately be issued.

Stock-based compensation expense or benefit and the related income tax benefit is presented in the following table. The service period for performance stock units granted each year begins on January 1 of the following year.

	Three Months Ended March 31,
	2022		2021
Non-vested stock units	$	2,358	$	1,883
Performance stock units	(246)		643
Total	$	2,112	$	2,526
Income tax benefit	$	708	$	367

Unrecognized stock-based compensation expense at March 31, 2022 is presented in the table below. Unrecognized stock-based compensation expense related to performance stock units is presented assuming attainment of the maximum payout rate as set forth by the performance criteria.

Non-vested stock units	$	16,063
Performance stock units	8,664
Total	$	24,727

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Note 11 - Earnings Per Common Share

Earnings per common share is computed using the two-class method as more fully described in our 2021 Form 10-K. The following table presents a reconciliation of net income available to common shareholders, net earnings allocated to common stock and the number of shares used in the calculation of basic and diluted earnings per common share.

	Three Months Ended March 31,
	2022		2021
Net income	$	99,102	$	116,015
Less: Preferred stock dividends	1,669		2,151
Net income available to common shareholders	97,433		113,864
Less: Earnings allocated to participating securities	849		1,162
Net earnings allocated to common stock	$	96,584	$	112,702
Distributed earnings allocated to common stock	$	48,051	$	45,660
Undistributed earnings allocated to common stock	48,533		67,042
Net earnings allocated to common stock	$	96,584	$	112,702
Weighted-average shares outstanding for basic earnings per common share	64,051,202		63,306,493
Dilutive effect of stock compensation	409,705		509,290
Weighted-average shares outstanding for diluted earnings per common share	64,460,907		63,815,783

Note 12 - Defined Benefit Plans

The components of the combined net periodic expense (benefit) for our defined benefit pension plans are presented in the table below.

	Three Months Ended March 31,
	2022		2021
Expected return on plan assets, net of expenses	$	(3,491)	$	(3,210)
Interest cost on projected benefit obligation	1,004		835
Net amortization and deferral	741		1,529
Net periodic expense (benefit)	$	(1,746)	$	(846)

Our non-qualified defined benefit pension plan is not funded. No contributions to the qualified defined benefit pension plan were made during the three months ended March 31, 2022. We do not expect to make any contributions to the qualified defined benefit plan during the remainder of 2022.

Note 13 - Income Taxes

Income tax expense was as follows:

	Three Months Ended March 31,
	2022			2021
Current income tax expense (benefit)	$	13,059		$	3,725
Deferred income tax expense (benefit)	(432)			4,172
Income tax expense, as reported	$	12,627		$	7,897
Effective tax rate	11.3		%	6.4		%

We had a net deferred tax asset totaling $110.3 million at March 31, 2022 and a net deferred tax liability totaling $81.2 million at December 31, 2021. No valuation allowance for deferred tax assets was recorded at March 31, 2022 as management believes it is more likely than not that all of the deferred tax assets will be realized against deferred tax liabilities and projected future taxable income.

The effective income tax rates differed from the U.S. statutory federal income tax rates of 21% during the comparable periods primarily due to the effect of tax-exempt income from loans, securities and life insurance policies and the income tax effects associated with stock-based compensation. There were no unrecognized tax benefits during any of the reported periods.

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Interest and/or penalties related to income taxes are reported as a component of income tax expense. Such amounts were not significant during the reported periods.

We file income tax returns in the U.S. federal jurisdiction. We are no longer subject to U.S. federal income tax examinations by tax authorities for years before 2018.

Note 14 - Other Comprehensive Income (Loss)

The before and after tax amounts allocated to each component of other comprehensive income (loss) are presented in the following table. Reclassification adjustments related to securities available for sale are included in net gain (loss) on securities transactions in the accompanying consolidated statements of income. Reclassification adjustments related to defined-benefit post-retirement benefit plans are included in the computation of net periodic pension expense (see Note 12 – Defined Benefit Plans).

	Three Months Ended March 31, 2022						Three Months Ended March 31, 2021
	Before Tax Amount		Tax  Expense, (Benefit)		Net of  Tax Amount		Before Tax Amount		Tax  Expense, (Benefit)		Net of  Tax Amount
Securities available for sale and transferred securities:
Change in net unrealized gain/loss during the period	$	(910,795)	$	(191,267)	$	(719,528)	$	(159,779)	$	(33,554)	$	(126,225)
Change in net unrealized gain on securities transferred to held to maturity	(209)		(44)		(165)		(259)		(54)		(205)
Reclassification adjustment for net (gains) losses included in net income	—		—		—		—		—		—
Total securities available for sale and transferred securities	(911,004)		(191,311)		(719,693)		(160,038)		(33,608)		(126,430)
Defined-benefit post-retirement benefit plans:
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic expense (benefit)	741		156		585		1,529		321		1,208
Total defined-benefit post-retirement benefit plans	741		156		585		1,529		321		1,208
Total other comprehensive income (loss)	$	(910,263)	$	(191,155)	$	(719,108)	$	(158,509)	$	(33,287)	$	(125,222)

Activity in accumulated other comprehensive income (loss), net of tax, was as follows:

	Securities Available For Sale		Defined Benefit Plans		Accumulated Other Comprehensive Income
Balance January 1, 2022	$	380,209	$	(32,891)	$	347,318
Other comprehensive income (loss) before reclassifications	(719,693)		—		(719,693)
Reclassification of amounts included in net income	—		585		585
Net other comprehensive income (loss) during period	(719,693)		585		(719,108)
Balance at March 31, 2022	$	(339,484)	$	(32,306)	$	(371,790)
Balance January 1, 2021	$	563,801	$	(50,831)	$	512,970
Other comprehensive income (loss) before reclassifications	(126,430)		—		(126,430)
Reclassification of amounts included in net income	—		1,208		1,208
Net other comprehensive income (loss) during period	(126,430)		1,208		(125,222)
Balance at March 31, 2021	$	437,371	$	(49,623)	$	387,748

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Note 15 – Operating Segments

We are managed under a matrix organizational structure whereby our two primary operating segments, Banking and Frost Wealth Advisors, overlap a regional reporting structure. See our 2021 Form 10-K for additional information regarding our operating segments. Summarized operating results by segment were as follows:

	Banking		Frost  Wealth Advisors		Non-Banks		Consolidated
Three months ended:
March 31, 2022
Net interest income (expense)	$	250,119	$	700	$	(1,748)	$	249,071
Credit loss expense (benefit)	(1)		1		—		—
Non-interest income	58,706		43,229		(545)		101,390
Non-interest expense	206,538		30,910		1,284		238,732
Income (loss) before income taxes	102,288		13,018		(3,577)		111,729
Income tax expense (benefit)	11,014		2,734		(1,121)		12,627
Net income (loss)	91,274		10,284		(2,456)		99,102
Preferred stock dividends	—		—		1,669		1,669
Net income (loss) available to common shareholders	$	91,274	$	10,284	$	(4,125)	$	97,433
Revenues from (expenses to) external customers	$	308,825	$	43,929	$	(2,293)	$	350,461
March 31, 2021
Net interest income (expense)	$	242,205	$	486	$	(1,810)	$	240,881
Credit loss expense	63		—		—		63
Non-interest income	53,780		39,609		(153)		93,236
Non-interest expense	179,151		29,937		1,054		210,142
Income (loss) before income taxes	116,771		10,158		(3,017)		123,912
Income tax expense (benefit)	7,177		2,133		(1,413)		7,897
Net income (loss)	109,594		8,025		(1,604)		116,015
Preferred stock dividends	—		—		2,151		2,151
Net income (loss) available to common shareholders	$	109,594	$	8,025	$	(3,755)	$	113,864
Revenues from (expenses to) external customers	$	295,985	$	40,095	$	(1,963)	$	334,117

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Note 16 – Fair Value Measurements

The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, we utilize valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability. ASC Topic 820 establishes a three-level fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. See our 2021 Form 10-K for additional information regarding the fair value hierarchy and a description of our valuation techniques.

Financial Assets and Financial Liabilities. The tables below summarize financial assets and financial liabilities measured at fair value on a recurring basis as of March 31, 2022 and December 31, 2021, segregated by the level of the valuation inputs within the fair value hierarchy of ASC Topic 820 utilized to measure fair value.

	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
March 31, 2022
Securities available for sale:
U.S. Treasury	$	3,507,746	$	—	$	—	$	3,507,746
Residential mortgage-backed securities	—		5,376,039		—		5,376,039
States and political subdivisions	—		7,258,393		—		7,258,393
Other	—		42,361		—		42,361
Trading account securities:
U.S. Treasury	23,939		—		—		23,939
States and political subdivisions	—		5,579		—		5,579
Derivative assets:
Interest rate swaps, caps and floors	—		33,697		—		33,697
Commodity swaps and options	—		252,747		—		252,747
Foreign currency forward contracts	150		—		—		150
Derivative liabilities:
Interest rate swaps, caps and floors	—		39,734		—		39,734
Commodity swaps and options	—		251,181		—		251,181
Foreign currency forward contracts	131		—		—		131
December 31, 2021
Securities available for sale:
U.S. Treasury	$	2,179,433	$	—	$	—	$	2,179,433
Residential mortgage-backed securities	—		4,066,265		—		4,066,265
States and political subdivisions	—		7,636,571		—		7,636,571
Other	—		42,359		—		42,359
Trading account securities:
U.S. Treasury	24,237		—		—		24,237
States and political subdivisions	—		925		—		925
Derivative assets:
Interest rate swaps, caps and floors	—		44,310		—		44,310
Commodity swaps and options	—		114,757		—		114,757
Foreign currency forward contracts	33		—		—		33
Derivative liabilities:
Interest rate swaps, caps and floors	—		25,261		—		25,261
Commodity swaps and options	—		113,261		—		113,261
Foreign currency forward contracts	55		—		—		55

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Certain financial assets and financial liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances. Financial assets measured at fair value on a non-recurring basis during the reported periods include certain collateral dependent loans reported at the fair value of the underlying collateral if repayment is expected solely from the collateral.

The following table presents collateral dependent loans that were remeasured and reported at fair value through a specific allocation of the allowance for credit losses on loans based upon the fair value of the underlying collateral during the reported periods.

	Three Months Ended March 31, 2022				Three Months Ended March 31, 2021
	Level 2		Level 3		Level 2		Level 3
Carrying value before allocations	$	2,064	$	5,711	$	100	$	15,013
Specific (allocations) reversals of prior allocations	(126)		3,965		—		600
Fair value	$	1,938	$	9,676	$	100	$	15,613

Non-Financial Assets and Non-Financial Liabilities. We do not have any non-financial assets or non-financial liabilities measured at fair value on a recurring basis. From time to time, non-financial assets measured at fair value on a non-recurring basis may include certain foreclosed assets which, upon initial recognition, were remeasured and reported at fair value through a charge-off to the allowance for loan losses and certain foreclosed assets which, subsequent to their initial recognition, were remeasured at fair value through a write-down included in other non-interest expense. There were no such fair value measurements during the reported periods.

Financial Instruments Reported at Amortized Cost. The estimated fair values of financial instruments that are reported at amortized cost in our consolidated balance sheets, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, were as follows:

	March 31, 2022				December 31, 2021
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Financial assets:
Level 2 inputs:
Cash and cash equivalents	$	14,457,083	$	14,457,083	$	16,583,000	$	16,583,000
Securities held to maturity	1,665,465		1,639,993		1,749,179		1,809,143
Cash surrender value of life insurance policies	189,471		189,471		190,139		190,139
Accrued interest receivable	131,370		131,370		179,111		179,111
Level 3 inputs:
Loans, net	16,295,702		16,053,955		16,087,731		16,079,454
Financial liabilities:
Level 2 inputs:
Deposits	44,430,929		44,422,700		42,695,696		41,343,426
Federal funds purchased	35,200		35,200		25,925		25,925
Repurchase agreements	1,842,618		1,842,618		2,740,799		2,740,799
Junior subordinated deferrable interest debentures	123,026		123,712		123,011		123,712
Subordinated notes	99,217		105,740		99,178		111,430
Accrued interest payable	2,147		2,147		3,026		3,026

Under ASC Topic 825, entities may choose to measure eligible financial instruments at fair value at specified election dates. The fair value measurement option (i) may be applied instrument by instrument, with certain exceptions, (ii) is generally irrevocable and (iii) is applied only to entire instruments and not to portions of instruments. Unrealized gains and losses on items for which the fair value measurement option has been elected must be reported in earnings at each subsequent reporting date. During the reported periods, we had no financial instruments measured at fair value under the fair value measurement option.

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Note 17 - Accounting Standards Updates

Information about certain recently issued accounting standards updates is presented below. Also refer to Note 20 - Accounting Standards Updates in our 2021 Form 10-K for additional information related to previously issued accounting standards updates.

ASU 2022-01, “Derivatives and Hedging (Topic 815): Fair Value Hedging - Portfolio Layer Method.” Under prior guidance, entities can apply the last-of-layer hedging method to hedge the exposure of a closed portfolio of prepayable financial assets to fair value changes due to changes in interest rates for a portion of the portfolio that is not expected to be affected by prepayments, defaults, and other events affecting the timing and amount of cash flows. ASU 2022-01 expands the last-of-layer method, which permits only one hedge layer, to allow multiple hedged layers of a single closed portfolio. To reflect that expansion, the last-of-layer method is renamed the portfolio layer method. ASU 2022-01 also (i) expands the scope of the portfolio layer method to include non-prepayable financial assets, (ii) specifies eligible hedging instruments in a single-layer hedge, (iii) provides additional guidance on the accounting for and disclosure of hedge basis adjustments under the portfolio layer method and (iv) specifies how hedge basis adjustments should be considered when determining credit losses for the assets included in the closed portfolio. ASU 2022-01 will be effective for us on January 1, 2023 though early adoption is permitted. The adoption of ASU 2022-01 is not expected to have a significant impact on our financial statements.

ASU 2022-02, “Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures.” ASU 2022-02 eliminates the accounting guidance for troubled debt restructurings in Accounting Standards Codification (“ASC”) Subtopic 310-40, Receivables - Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Additionally, ASU 2022-02 requires entities to disclose current-period gross write-offs by year of origination for financing receivables and net investments in leases within the scope of ASC Subtopic 3126-20, Financial Instruments - Credit Losses - Measured at Amortized Cost. ASU 2022-02 will be effective for us on January 1, 2023 though early adoption is permitted. The adoption of ASU 2022-02 is not expected to have a significant impact on our financial statements.

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Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

Financial Review

Cullen/Frost Bankers, Inc.

The following discussion should be read in conjunction with our consolidated financial statements, and notes thereto, for the year ended December 31, 2021, and the other information included in the 2021 Form 10-K. Operating results for the three months ended March 31, 2022 are not necessarily indicative of the results for the year ending December 31, 2022 or any future period.

Dollar amounts in tables are stated in thousands, except for per share amounts.

Forward-Looking Statements and Factors that Could Affect Future Results

Certain statements contained in this Quarterly Report on Form 10-Q that are not statements of historical fact constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 (the “Act”), including statements regarding the potential effects of the ongoing COVID-19 pandemic on our business, financial condition, liquidity and results of operations, notwithstanding that such statements are not specifically identified as such. In addition, certain statements may be contained in our future filings with the SEC, in press releases, and in oral and written statements made by us or with our approval that are not statements of historical fact and constitute forward-looking statements within the meaning of the Act. Examples of forward-looking statements include, but are not limited to: (i) projections of revenues, expenses, income or loss, earnings or loss per share, the payment or nonpayment of dividends, capital structure and other financial items; (ii) statements of plans, objectives and expectations of Cullen/Frost or its management or Board of Directors, including those relating to products, services or operations; (iii) statements of future economic performance; and (iv) statements of assumptions underlying such statements. Words such as “believes”, “anticipates”, “expects”, “intends”, “targeted”, “continue”, “remain”, “will”, “should”, “may” and other similar expressions are intended to identify forward-looking statements but are not the exclusive means of identifying such statements.

Forward-looking statements involve risks and uncertainties that may cause actual results to differ materially from those in such statements. Factors that could cause actual results to differ from those discussed in the forward-looking statements include, but are not limited to:

•Local, regional, national and international economic conditions and the impact they may have on us and our customers and our assessment of that impact.

•Volatility and disruption in national and international financial and commodity markets.

•Government intervention in the U.S. financial system.

•Changes in the mix of loan geographies, sectors and types or the level of non-performing assets and charge-offs.

•Changes in estimates of future reserve requirements based upon the periodic review thereof under relevant regulatory and accounting requirements.

•The effects of and changes in trade and monetary and fiscal policies and laws, including the interest rate policies of the Federal Reserve Board.

•Inflation, interest rate, securities market and monetary fluctuations.

•The effect of changes in laws and regulations (including laws and regulations concerning taxes, banking, securities and insurance) and their application with which we and our subsidiaries must comply.

•The soundness of other financial institutions.

•Political instability.

•Impairment of our goodwill or other intangible assets.

•Acts of God or of war or terrorism.

•The potential impact of climate change.

•The timely development and acceptance of new products and services and perceived overall value of these products and services by users.

•Changes in consumer spending, borrowings and savings habits.

•Changes in the financial performance and/or condition of our borrowers.

•Technological changes.

•The cost and effects of cyber incidents or other failures, interruptions or security breaches of our systems or those of our customers or third-party providers.

•Acquisitions and integration of acquired businesses.

•Our ability to increase market share and control expenses.

•Our ability to attract and retain qualified employees.

•Changes in the competitive environment in our markets and among banking organizations and other financial service providers.

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•The effect of changes in accounting policies and practices, as may be adopted by the regulatory agencies, as well as the Public Company Accounting Oversight Board, the Financial Accounting Standards Board and other accounting standard setters.

•Changes in the reliability of our vendors, internal control systems or information systems.

•Changes in our liquidity position.

•Changes in our organization, compensation and benefit plans.

•The impact of the ongoing COVID-19 pandemic and any other pandemic, epidemic or health-related crisis.

•The costs and effects of legal and regulatory developments, the resolution of legal proceedings or regulatory or other governmental inquiries, the results of regulatory examinations or reviews and the ability to obtain required regulatory approvals.

•Greater than expected costs or difficulties related to the integration of new products and lines of business.

•Our success at managing the risks involved in the foregoing items.

In addition, financial markets and global supply chains may be adversely affected by the current or anticipated impact of military conflict, including the current Russian invasion of Ukraine, terrorism or other geopolitical events.

Further, statements about the potential effects of the ongoing COVID-19 pandemic on our business, financial condition, liquidity and results of operations may constitute forward-looking statements and are subject to the risk that the actual effects may differ, possibly materially, from what is reflected in those forward-looking statements due to factors and future developments that are uncertain, unpredictable and in many cases beyond our control, including the scope and duration of the pandemic, actions taken by governmental authorities in response to the pandemic, and the direct and indirect impact of the pandemic on our customers, clients, third parties and us.

Forward-looking statements speak only as of the date on which such statements are made. We do not undertake any obligation to update any forward-looking statement to reflect events or circumstances after the date on which such statement is made, or to reflect the occurrence of unanticipated events.

COVID-19 Effects and Actions

Our business has been, and continues to be, impacted by the effects of the COVID-19 pandemic. There remains many uncertainties related to COVID-19 including, among other things, the ongoing impact to our customers, employees and vendors; the impact to the financial services and banking industry; and the impact to the economy as a whole as well as the effect of actions taken, or that may yet be taken, or inaction by governmental authorities to mitigate both the economic and health-related effects of COVID-19. Refer to our 2021 Form 10-K for further information regarding (i) the impact of the COVID-19 pandemic on our operations and our results thereof, as well as the impact on our financial position and (ii) legislative and regulatory actions taken related to the COVID-19 pandemic, particularly as they relate to the banking and financial services industry.

Application of Critical Accounting Policies and Accounting Estimates

We follow accounting and reporting policies that conform, in all material respects, to accounting principles generally accepted in the United States and to general practices within the financial services industry. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. While we base estimates on historical experience, current information and other factors deemed to be relevant, actual results could differ from those estimates.

We consider accounting estimates to be critical to reported financial results if (i) the accounting estimate requires management to make assumptions about matters that are highly uncertain and (ii) different estimates that management reasonably could have used for the accounting estimate in the current period, or changes in the accounting estimate that are reasonably likely to occur from period to period, could have a material impact on our financial statements.

Accounting policies related to the allowance for credit losses on financial instruments including loans and off-balance-sheet credit exposures are considered to be critical as these policies involve considerable subjective judgment and estimation by management. In the case of loans, the allowance for credit losses is a contra-asset valuation account, calculated in accordance with Accounting Standards Codification (“ASC”) Topic 326 (“ASC 326”) Financial Instruments - Credit Losses, that is deducted from the amortized cost basis of loans to present the net amount expected to be collected. In the case of off-balance-sheet credit exposures, the allowance for credit losses is a liability account, calculated in accordance with ASC 326, reported as a component of accrued interest payable and other liabilities in our consolidated balance sheets. The amount of each allowance account represents management's best estimate of current expected credit losses on these financial instruments considering available information, from internal and external sources, relevant to assessing exposure to credit loss over the contractual term

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of the instrument. Relevant available information includes historical credit loss experience, current conditions and reasonable and supportable forecasts. While historical credit loss experience provides the basis for the estimation of expected credit losses, adjustments to historical loss information may be made for differences in current portfolio-specific risk characteristics, environmental conditions or other relevant factors. While management utilizes its best judgment and information available, the ultimate adequacy of our allowance accounts is dependent upon a variety of factors beyond our control, including the performance of our portfolios, the economy, changes in interest rates and the view of the regulatory authorities toward classification of assets. Refer to the 2021 Form 10-K for additional information regarding critical accounting policies.

Overview

A discussion of our results of operations is presented below. Certain reclassifications have been made to make prior periods comparable. Taxable-equivalent adjustments are the result of increasing income from tax-free loans and investments by an amount equal to the taxes that would be paid if the income were fully taxable based on a 21% federal tax rate, thus making tax-exempt yields comparable to taxable asset yields.

Results of Operations

Net income available to common shareholders totaled $97.4 million, or $1.50 per diluted common share, for the three months ended March 31, 2022 compared to $113.9 million, or $1.77 per diluted common share, for the three months ended March 31, 2021.

Selected data for the comparable periods was as follows:

	Three Months Ended March 31,
	2022			2021
Taxable-equivalent net interest income	$	272,194		$	263,949
Taxable-equivalent adjustment	23,123			23,068
Net interest income	249,071			240,881
Credit loss expense	—			63
Net interest income after credit loss expense	249,071			240,818
Non-interest income	101,390			93,236
Non-interest expense	238,732			210,142
Income before income taxes	111,729			123,912
Income taxes	12,627			7,897
Net income	99,102			116,015
Preferred stock dividends	1,669			2,151
Redemption of preferred stock	—			—
Net income available to common shareholders	$	97,433		$	113,864
Earnings per common share – basic	$	1.51		$	1.78
Earnings per common share – diluted	1.50			1.77
Dividends per common share	0.75			0.72
Return on average assets	0.79		%	1.09		%
Return on average common equity	9.58			11.13
Average shareholders’ equity to average assets	8.48			10.10

Net income available to common shareholders decreased $16.4 million, or 14.4%, for the three months ended March 31, 2022 compared to the same period in 2021. The decrease during the three months ended March 31, 2022 was primarily the result of a $28.6 million increase in non-interest expense and a $4.7 million increase in income tax expense partly offset by an $8.2 million increase in net interest income and an $8.2 million increase in non-interest income. Details of the changes in the various components of net income are further discussed below.

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Net Interest Income

Net interest income is the difference between interest income on earning assets, such as loans and securities, and interest expense on liabilities, such as deposits and borrowings, which are used to fund those assets. Net interest income is our largest source of revenue, representing 71.1% of total revenue during the first three months of 2022. Net interest margin is the ratio of taxable-equivalent net interest income to average earning assets for the period. The level of interest rates and the volume and mix of earning assets and interest-bearing liabilities impact net interest income and net interest margin.

The Federal Reserve influences the general market rates of interest, including the deposit and loan rates offered by many financial institutions. Our loan portfolio is significantly affected by changes in the prime interest rate. The prime rate remained at 3.25% during 2021. During 2022, the prime rate increased 25 basis points in March to end the first quarter at 3.50%. Our loan portfolio is also impacted by changes in the London Interbank Offered Rate (“LIBOR”). At March 31, 2022, the one-month and three-month U.S. dollar LIBOR interest rates were 0.45% and 0.96%, respectively, while at March 31, 2021, the one-month and three-month U.S. dollar LIBOR interest rates were 0.11% and 0.19%, respectively. We discontinued originating LIBOR-based loans effective December 31, 2021 and have begun to negotiate loans using our preferred replacement index, the American Interbank Offered Rate (“AMERIBOR”), a benchmark developed by the American Financial Exchange, the Secured Overnight Financing Rate (“SOFR”) or a benchmark developed by Bloomberg Index Services (“BSBY”). For our currently outstanding LIBOR-based loans, the timing and manner in which each customer’s contract transitions from LIBOR to another rate will vary on a case-by-case basis. We expect to complete all transitions by the first quarter of 2023.

The target range for the federal funds rate, which is the cost of immediately available overnight funds, remained at zero to 0.25% during 2021. During 2022, the target fed funds rate was increased 25 basis points in March to end the quarter at 0.25 to 0.50%. In March 2022, the Federal Reserve released projections whereby the midpoint of the projected appropriate target range for the federal funds rate would rise to 1.9% by the end of 2022 and to 2.8% by the end of 2023. While there can be no such assurance that any increases in the federal funds rate will occur, these projections imply six 25 basis point increases in the federal funds rate during the remainder of 2022, followed by an additional four 25 basis point increases in 2023.

We are primarily funded by core deposits, with non-interest-bearing demand deposits historically being a significant source of funds. This lower-cost funding base is expected to have a positive impact on our net interest income and net interest margin in a rising interest rate environment. See Item 3. Quantitative and Qualitative Disclosures About Market Risk elsewhere in this report for information about our sensitivity to interest rates. Further analysis of the components of our net interest margin is presented below.

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The following table presents an analysis of net interest income and net interest spread for the periods indicated, including average outstanding balances for each major category of interest-earning assets and interest-bearing liabilities, the interest earned or paid on such amounts, and the average rate earned or paid on such assets or liabilities, respectively. The table also sets forth the net interest margin on average total interest-earning assets for the same periods. For these computations: (i) average balances are presented on a daily average basis, (ii) information is shown on a taxable-equivalent basis assuming a 21% tax rate, (iii) average loans include loans on non-accrual status, and (iv) average securities include unrealized gains and losses on securities available for sale, while yields are based on average amortized cost.

	March 31, 2022						March 31, 2021
	Average Balance		Interest Income/ Expense		Yield/ Cost		Average Balance		Interest Income/ Expense		Yield/ Cost
Assets:
Interest-bearing deposits	$	13,766,486	$	6,343	0.18	%	$	9,864,811	$	2,433	0.10	%
Federal funds sold	13,892		13		0.37		4,963		3		0.24
Resell agreements	5,835		4		0.27		2,636		1		0.15
Securities:
Taxable	9,000,677		43,058		1.90		4,017,748		20,028		2.06
Tax-exempt	8,165,462		78,898		4.03		8,229,643		78,576		4.09
Total securities	17,166,139		121,956		2.88		12,247,391		98,604		3.41
Loans, net of unearned discounts	16,386,458		151,068		3.74		17,683,917		168,638		3.87
Total Earning Assets and Average Rate Earned	47,338,810		279,384		2.39		39,803,718		269,679		2.78
Cash and due from banks	651,124						530,954
Allowance for credit losses on loans and securities	(248,801)						(267,233)
Premises and equipment, net	1,050,735						1,045,943
Accrued interest and other assets	1,531,609						1,416,614
Total Assets	$	50,323,477					$	42,529,996
Liabilities:
Non-interest-bearing demand deposits	17,961,221						15,309,375
Interest-bearing deposits:
Savings and interest checking	11,954,465		410		0.01		9,713,591		356		0.01
Money market deposit accounts	11,858,775		3,651		0.12		9,244,763		1,679		0.07
Time accounts	1,187,458		851		0.29		1,138,240		1,482		0.53
Total interest-bearing deposits	25,000,698		4,912		0.08		20,096,594		3,517		0.07
Total deposits	42,961,919				0.05		35,405,969				0.04
Federal funds purchased	27,759		12		0.17		40,614		8		0.08
Repurchase agreements	2,051,577		518		0.10		1,839,982		395		0.09
Junior subordinated deferrable interest debentures	123,020		584		1.90		136,366		646		1.89
Subordinated notes	99,203		1,164		4.69		99,046		1,164		4.70
Total Interest-Bearing Funds and Average Rate Paid	27,302,257		7,190		0.11		22,212,602		5,730		0.10
Accrued interest and other liabilities	790,092						713,002
Total Liabilities	46,053,570						38,234,979
Shareholders’ Equity	4,269,907						4,295,017
Total Liabilities and Shareholders’ Equity	$	50,323,477					$	42,529,996
Net interest income			$	272,194					$	263,949
Net interest spread					2.28	%					2.68	%
Net interest income to total average earning assets					2.33	%					2.72	%

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The following table presents the changes in taxable-equivalent net interest income and identifies the changes due to differences in the average volume of earning assets and interest-bearing liabilities and the changes due to changes in the average interest rate on those assets and liabilities. The changes in net interest income due to changes in both average volume and average interest rate have been allocated to the average volume change or the average interest rate change in proportion to the absolute amounts of the change in each.

	Three Months Ended
	March 31, 2022 vs. March 31, 2021
	Increase (Decrease) Due to Change in
	Rate		Volume		Total
Interest-bearing deposits	$	2,617	$	1,293	$	3,910
Federal funds sold	3		7		10
Resell agreements	2		1		3
Securities:
Taxable	(1,684)		24,714		23,030
Tax-exempt	(1,208)		1,530		322
Loans, net of unearned discounts	(5,518)		(12,052)		(17,570)
Total earning assets	(5,788)		15,493		9,705
Savings and interest checking	—		54		54
Money market deposit accounts	1,413		559		1,972
Time accounts	(695)		64		(631)
Federal funds purchased	7		(3)		4
Repurchase agreements	60		63		123
Junior subordinated deferrable interest debentures	3		(65)		(62)
Subordinated notes	(2)		2		—
Total interest-bearing liabilities	786		674		1,460
Net change	$	(6,574)	$	14,819	$	8,245

Taxable-equivalent net interest income for the three months ended March 31, 2022 increased $8.2 million, or 3.1%, compared to the same period in 2021. The increase in taxable-equivalent net interest income during the three months ended March 31, 2022 was primarily related to an increase in the average volume of taxable securities and, to a much lesser extent, increases in the average volumes of interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) and tax-exempt securities; and an increase in the average yield on interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve). The impact of these items was partly offset by a decrease in the average volume of loans combined with decreases in the average yields on loans, taxable securities and tax-exempt securities and increases in the average cost and average volume of money market deposit accounts. As a result of these fluctuations, the taxable-equivalent net interest margin decreased 39 basis points from 2.72% during the three months ended March 31, 2021 to 2.33% during the three months ended March 31, 2022.

The average volume of interest-earning assets for the three months ended March 31, 2022 increased $7.5 billion compared to the same period in 2021. The increase in the average volume of interest-earning assets primarily related to a $5.0 billion increase in average taxable securities and a $3.9 billion increase in average interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) partly offset by a $1.3 billion decrease in average loans (of which approximately $2.5 billion related to PPP loans, as further discussed below).

The average taxable-equivalent yield on loans decreased 13 basis points from 3.87% during the three months ended March 31, 2021 to 3.74% during the three months ended March 31, 2022. The average taxable-equivalent yield on loans during the three months ended March 31, 2021 was positively impacted by a higher average proportion of higher-yielding PPP loans to total loans compared to the three months ended March 31, 2022. The average volume of loans for the three months ended March 31, 2022 decreased $1.3 billion, or 7.3%, compared to the same period in 2021. The decrease was primarily due to a $2.5 billion decrease in the average volume of PPP loans. Excluding PPP loans, average loans would have increased $1.2 billion, or 8.3%. Loans made up approximately 34.6% of average interest-earning assets during the three months ended March 31, 2022, compared to 44.4% during the same period in 2021.

During the three months ended March 31, 2022, we recognized approximately $2.6 million in PPP loan related deferred processing fees (net of amortization of related deferred origination costs) as a yield adjustment and this amount is included in interest income on loans. During the three months ended March 31, 2021, we recognized approximately $23.5 million in PPP loan related deferred processing fees (net of amortization of related deferred origination costs). As a result of the inclusion of

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these net fees in interest income, the average yields on PPP loans was 4.45% during the three months ended March 31, 2022, and 4.39% during the three months ended March 31, 2021, compared to the stated interest rate of 1.0% on these loans.

The average taxable-equivalent yield on securities was 2.88% during the three months ended March 31, 2022, decreasing 53 basis points from 3.41% during the same period in 2021. The average yield on taxable securities decreased 16 basis points from 2.06% during the three months ended March 31, 2021 to 1.90% during the three months ended March 31, 2022. The average taxable-equivalent yield on tax-exempt securities decreased 6 basis points from 4.09% during the three months ended March 31, 2021 to 4.03% during the three months ended March 31, 2022. Tax exempt securities made up approximately 47.6% of total average securities during the three months ended March 31, 2022 compared to 67.2% during the same period in 2021. The average volume of total securities during the three months ended March 31, 2022 increased $4.9 billion, or 40.2%, compared to the same period in 2021. Securities made up approximately 36.3% of average interest-earning assets during the three months ended March 31, 2022 compared to 30.8% during the same period in 2021. The increase during the three months ended March 31, 2022 was primarily related to the increased investment of funds in taxable securities.

Average interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) for the three months ended March 31, 2022 increased $3.9 billion, or 39.6%, compared to the same period in 2021. Interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) made up approximately 29.1% of average interest-earning assets during the three months ended March 31, 2022 compared to 24.8% during the same period in 2021. The increase in the average volume of interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) during the three months ended March 31, 2022 compared to the same period in 2021 was primarily due to increases in the average volume of customer deposits. The average yield on interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) was 0.18% during the three months ended March 31, 2022 compared to 0.10% during the same period in 2021. The average yield on interest-bearing deposits during the three months ended March 31, 2022 was impacted by higher interest rate paid on excess reserves held at the Federal Reserve, compared to the same period in 2021.

The average rate paid on interest-bearing liabilities was 0.11% during the three months ended March 31, 2022, increasing one basis point from 0.10% during the same period in 2021. Average deposits increased $7.6 billion, or 21.3%, during the three months ended March 31, 2022 compared to the same period in 2021 and included a $4.9 billion increase in average interest-bearing deposits and a $2.7 billion increase in average non-interest bearing deposits. The ratio of average interest-bearing deposits to total average deposits was 58.2% during the three months ended March 31, 2022 compared to 56.8% during the same period in 2021. The average cost of deposits is primarily impacted by changes in market interest rates as well as changes in the volume and relative mix of interest-bearing deposits. The average cost of interest-bearing deposits and total deposits was 0.08% and 0.05%, respectively, during the three months ended March 31, 2022 compared to 0.07% and 0.04%, respectively, during the same period in 2021. The average cost of deposits during 2022 was impacted by an increase in the interest rates we pay on most of our interest-bearing deposit products as a result of the aforementioned increase in market interest rates.

Our net interest spread, which represents the difference between the average rate earned on earning assets and the average rate paid on interest-bearing liabilities, was 2.28% during the three months ended March 31, 2022 compared to 2.68% during the same period in 2021. The net interest spread, as well as the net interest margin, will be impacted by future changes in short-term and long-term interest rate levels, as well as the impact from the competitive environment. A discussion of the effects of changing interest rates on net interest income is set forth in Item 3. Quantitative and Qualitative Disclosures About Market Risk included elsewhere in this report.

Our hedging policies permit the use of various derivative financial instruments, including interest rate swaps, swaptions, caps and floors, to manage exposure to changes in interest rates. Details of our derivatives and hedging activities are set forth in Note 8 - Derivative Financial Instruments in the accompanying notes to consolidated financial statements included elsewhere in this report. Information regarding the impact of fluctuations in interest rates on our derivative financial instruments is set forth in Item 3. Quantitative and Qualitative Disclosures About Market Risk included elsewhere in this report.

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Credit Loss Expense

Credit loss expense is determined by management as the amount to be added to the allowance for credit loss accounts for various types of financial instruments including loans, securities and off-balance-sheet credit exposures after net charge-offs have been deducted to bring the allowances to a level which, in management’s best estimate, is necessary to absorb expected credit losses over the lives of the respective financial instruments. The components of credit loss expense were as follows:

	Three Months Ended March 31,
	2022		2021
Credit loss expense (benefit) related to:
Loans	$	4,464	$	—
Off-balance-sheet credit exposures	(4,464)		65
Securities held to maturity	—		(2)
Total	$	—	$	63

See the section captioned “Allowance for Credit Losses” elsewhere in this discussion for further analysis of credit loss expense related to loans and off-balance-sheet credit exposures.

Non-Interest Income

Total non-interest income for the three months ended March 31, 2022 increased $8.2 million, or 8.7%, compared to the same period in 2021. Changes in the various components of non-interest income are discussed in more detail below.

Trust and Investment Management Fees. Trust and investment management fees for the three months ended March 31, 2022 increased $3.3 million, or 9.5%, compared to the same period in 2021. Investment management fees are the most significant component of trust and investment management fees, making up approximately 81.6% and 84.1% of total trust and investment management fees for the first three months of 2022 and 2021, respectively. The increase in trust and investment management fees was primarily due to increases in investment management fees (up $1.8 million, or 6.2%), oil and gas fees (up $771 thousand) and real estate fees (up $626 thousand). Investment management fees are generally based on the market value of assets within an account and are thus impacted by volatility in the equity and bond markets. The increase in investment management fees was primarily related to higher average equity valuations as well as an increase in the number of accounts. Oil and gas fees were impacted by increases in oil and gas prices. The increase in real estate fees was primarily related to an increase in transaction volume.

At March 31, 2022, trust assets, including both managed assets and custody assets, were primarily composed of equity securities (46.1% of assets), fixed income securities (31.4% of assets), alternative investments (6.8% of assets) and cash equivalents (9.7% of assets). The estimated fair value of these assets was $42.4 billion (including managed assets of $20.8 billion and custody assets of $21.6 billion) at March 31, 2022, compared to $43.3 billion (including managed assets of $19.1 billion and custody assets of $24.2 billion) at December 31, 2021 and $39.3 billion (including managed assets of $17.3 billion and custody assets of $22.0 billion) at March 31, 2021.

Service Charges on Deposit Accounts. Service charges on deposit accounts for the three months ended March 31, 2022 increased $2.7 million, or 13.7%, compared to the same period in 2021. The increase was primarily related to increases in commercial service charges (up $1.5 million) and overdraft charges on consumer and commercial accounts (up $637 thousand and $475 thousand, respectively). Commercial service charges during the three months ended March 31, 2022 were impacted by an increase in the volume of billable services compared to the same period in 2021, partly offset by an increase in the earnings credit rate. The earnings credit rate is the value given to deposits maintained by treasury management customers. Earnings credits applied to customer deposit balances offset service fees that would otherwise be charged. Overdraft charges totaled $8.7 million ($6.7 million consumer and $2.0 million commercial) during the three months ended March 31, 2022 compared to $7.5 million ($6.0 million consumer and $1.5 million commercial) during the same period in 2021. The increases in overdraft charges during the three months ended March 31, 2022 were impacted by increases in the volumes of fee assessed overdrafts relative to the same period in 2021.

Insurance Commissions and Fees. Insurance commissions and fees for the three months ended March 31, 2022 decreased $705 thousand, or 4.1%, compared to the same period in 2021. The decrease was the result of a decrease in contingent income (down $1.2 million) partly offset by an increase in commission income (up $525 thousand).

Contingent income totaled $2.4 million during the three months ended March 31, 2022 compared to $3.7 million during the same period in 2021. Contingent income primarily consists of amounts received from various property and casualty insurance carriers related to portfolio growth and the loss performance of insurance policies previously placed. These performance related

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contingent payments are seasonal in nature and are mostly received during the first quarter of each year. This performance related contingent income totaled $1.6 million and $3.0 million during the three months ended March 31, 2022 and 2021, respectively. The decrease in performance related contingent income during 2022 was related to low growth within the portfolio and a deterioration in the loss performance of insurance policies previously placed. This deterioration was impacted by a severe weather event in Texas during the first quarter of 2021 that resulted in a significant increase in property and casualty claims and losses. Contingent income also includes amounts received from various benefit plan insurance companies related to the volume of business generated and/or the subsequent retention of such business. This benefit plan related contingent income totaled $813 thousand during the three months ended March 31, 2022 compared to $625 thousand during the same period in 2021.

The increase in commission income during the three months ended March 31, 2022 was primarily related to an increase in commercial lines property and casualty commissions partly offset by a decrease in life insurance commissions. The increase in commercial lines property and casualty commissions was related to increased business volumes and increased market rates while the decrease in life insurance commissions was related to a decrease in business volumes.

Interchange and Card Transaction Fees. Interchange fees, or “swipe” fees, are charges that merchants pay to us and other card-issuing banks for processing electronic payment transactions. Interchange and card transaction fees consist of income from debit and credit card usage, point of sale income from PIN-based card transactions and ATM service fees. Interchange and card transaction fees are reported net of related network costs.

Net interchange and card transaction fees for the three months ended March 31, 2022 increased $133 thousand, or 3.2%, compared to the same period in 2021 primarily due to an increase in transaction volumes as well as the impact of new card products partly offset by an increase in network costs. A comparison of gross and net interchange and card transaction fees for the reported periods is presented in the table below.

	Three Months Ended March 31,
	2022		2021
Income from card transactions	$	7,481	$	6,392
ATM service fees	764		785
Gross interchange and card transaction fees	8,245		7,177
Network costs	4,019		3,084
Net interchange and card transaction fees	$	4,226	$	4,093

Federal Reserve rules applicable to financial institutions that have assets of $10 billion or more provide that the maximum permissible interchange fee for an electronic debit transaction is the sum of 21 cents per transaction and 5 basis points multiplied by the value of the transaction. An upward adjustment of no more than 1 cent to an issuer's debit card interchange fee is allowed if the card issuer develops and implements policies and procedures reasonably designed to achieve certain fraud-prevention standards. The Federal Reserve also has rules governing routing and exclusivity that require issuers to offer two unaffiliated networks for routing transactions on each debit or prepaid product.

Other Charges, Commissions and Fees. Other charges, commissions and fees for the three months ended March 31, 2022 increased $1.3 million, or 15.9%, compared to the same period in 2021. The increase was primarily related to increases in merchant services rebates (up $426 thousand), letter of credit fees (up $325 thousand) and income from the sale of mutual funds (up $321 thousand), among other things.

Other Non-Interest Income. Other non-interest income for the three months ended March 31, 2022 increased $1.3 million, or 16.0%, compared to the same period in 2021.The increase was primarily related to increases in public finance underwriting fees (up $1.6 million), sundry and other miscellaneous income (up $1.1 million) and income from customer foreign exchange transactions (up $380 thousand) partly offset by decreases in income from customer derivative transactions (down $1.2 million), among other things. The increases in public finance underwriting fees and income from customer foreign exchange transactions were primarily related to increases in transaction volumes. Sundry income during the three months ended March 31, 2022 included $522 thousand related to the recovery of prior write-offs and $458 thousand related to a contract fee. The decrease in income from customer derivative transactions was primarily due to a decrease in transaction volume.

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Non-Interest Expense

Total non-interest expense for the three months ended March 31, 2022 increased $28.6 million, or 13.6%, compared to the same period in 2021. Changes in the various components of non-interest expense are discussed below.

Salaries and Wages. Salaries and wages for the three months ended March 31, 2022 increased $17.9 million, or 19.1%, compared to the same period in 2021. The increase in salaries and wages was primarily related to an increase in salaries, due to normal, annual merit and market increases as well as the implementation of a $20 per hour minimum wage in December, 2021. Salaries and wages was also impacted by an increase in the number of employees, an increase in incentive compensation and a decrease in salary costs deferred in connection with loan originations as the first quarter of 2021 was impacted by the high volume of PPP loan originations. We are experiencing an increasingly competitive labor market which has resulted in and could continue to result in an increase in our staffing costs.

Employee Benefits. Employee benefits expense for the three months ended March 31, 2022 increased $1.7 million, or 7.5%, compared to the same period in 2021. The increase was primarily related to increases in payroll taxes and 401(k) plan expense, among other things, partly offset by an increase in the net periodic benefit related to our defined benefit retirement plan.

Our defined benefit retirement and restoration plans were frozen in 2001 which has helped to reduce the volatility in retirement plan expense. We nonetheless still have funding obligations related to these plans and could recognize expense related to these plans in future years, which would be dependent on the return earned on plan assets, the level of interest rates and employee turnover. See Note 12 - Defined Benefit Plans for additional information related to our net periodic pension benefit/cost.

Net Occupancy. Net occupancy expense for the three months ended March 31, 2022 increased $1.4 million, or 5.2%, compared to the same period in 2021. The increase was primarily related to increases in repairs and maintenance/service contracts expense (up $737 thousand) and depreciation on buildings and leasehold improvements (together up $355 thousand), among other things. The increases in the aforementioned components of net occupancy expense were impacted, in part, by our expansion within the Houston and Dallas market areas.

Technology, Furniture and Equipment. Technology, furniture and equipment expense for the three months ended March 31, 2022 increased $1.1 million, or 4.1%, compared to the same period in 2021. The increase was primarily related to increases in cloud services expense (up $809 thousand) and depreciation of furniture and equipment (up $515 thousand), among other things, partly offset by a decrease in software maintenance (down $358 thousand).

Deposit Insurance. Deposit insurance expense totaled $3.6 million for the three months ended March 31, 2022, compared to $2.9 million for the three months ended March 31, 2021. The increase was primarily related to an increase in total assets partly offset by a decrease in the assessment rate.

Other Non-Interest Expense. Other non-interest expense for the three months ended March 31, 2022 increased $5.9 million, or 15.9%, compared to the same period in 2021. The increase included increases in advertising/promotions expense (up $2.1 million); professional services expense (up $1.8 million); travel, meals and entertainment (up $1.2 million); and a decrease in costs deferred as loan origination costs (down $1.1 million); among other things. The impact of the aforementioned items was partly offset by decreases in donations expense (down $1.5 million), which was impacted by a $1.5 million contribution to the Frost Charitable Foundation in the first quarter of 2021; sundry and other miscellaneous expenses (down $876 thousand); and amortization of deferred costs associated with loan commitments (down $409 thousand), among other things.

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Results of Segment Operations

We are managed under a matrix organizational structure whereby our two primary operating segments, Banking and Frost Wealth Advisors, overlap a regional reporting structure. A third operating segment, Non-Banks, is for the most part the parent holding company, as well as certain other insignificant non-bank subsidiaries of the parent that, for the most part, have little or no activity. A description of each segment, the methodologies used to measure segment financial performance and summarized operating results by segment are described in Note 15 - Operating Segments in the accompanying notes to consolidated financial statements included elsewhere in this report. Segment operating results are discussed in more detail below.

Banking

Net income for the three months ended March 31, 2022 decreased $18.3 million, or 16.7%, compared to the same period in 2021. The decrease was primarily the result of a $27.4 million increase in non-interest expense and a $3.8 million increase in income tax expense partly offset by a $7.9 million increase in net interest income and a $4.9 million increase in non-interest income.

Net interest income for the three months ended March 31, 2022 increased $7.9 million, or 3.3%, compared to the same period in 2021. The increase was primarily related to an increase in the average volume of taxable securities and, to a much lesser extent, increases in the average volumes of interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) and tax-exempt securities; and an increase in the average yield on interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve). The impact of these items was partly offset by a decrease in the average volume of loans combined with decreases in the average yields on loans, taxable securities and tax-exempt securities and increases in the average cost and average volume of money market deposit accounts. See the analysis of net interest income included in the section captioned “Net Interest Income” included elsewhere in this discussion.

Credit loss expense/benefit was not significant for the Banking segment during the reported periods. See the sections captioned “Credit Loss Expense” and “Allowance for Credit Losses” elsewhere in this discussion for further analysis of credit loss expense related to loans and off-balance-sheet commitments.

Non-interest income for the three months ended March 31, 2022 increased $4.9 million, or 9.2%, compared to the same period in 2021. The increase was primarily due to increases in service charges on deposit accounts; other non-interest income; and other charges, commissions and fees partly offset by a decrease in insurance commissions and fees. The increase in service charges on deposit accounts was primarily related to increases in commercial service charges, due to an increase in the volume of billable services partly offset by a decrease in the earnings credit rate, and overdraft charges on consumer and commercial accounts, due to increases in the volumes of fee assessed overdrafts. The increase in other non-interest income was primarily related to increases in public finance underwriting fees and income from customer foreign exchange transactions, due to increases in transaction volumes, as well as an increase in sundry and other miscellaneous income, which was partly impacted by a recovery of prior write-offs and the recognition of a contract fee. These items were partly offset by a decrease in income from customer derivative transactions, due to a decrease in transaction volume, among other things. The increase in other charges, commissions and fees was primarily related to increases in merchant services rebates and letter of credit fees, among other things. The decrease in insurance commissions and fees was the result of a decrease in contingent income partly offset by an increase in commission income, which is further discussed below in relation to Frost Insurance Agency. See the analysis of these categories of non-interest income included in the section captioned “Non-Interest Income” included elsewhere in this discussion.

Non-interest expense increased $27.4 million, or 15.3%, for three months ended March 31, 2022 compared to the same period in 2021. The increase during the three months ended March 31, 2022 was primarily due to increases in salaries and wages and other non-interest expense and, to a lesser extent, increases in net occupancy expense; employee benefit expense; technology, furniture and equipment expense and deposit insurance expense. The increase in salaries and wages was primarily related to an increase in salaries, due to normal, annual merit and market increases as well as the implementation of a $20 per hour minimum wage in December, 2021. Salaries and wages was also impacted by an increase in the number of employees, an increase in incentive compensation and a decrease in salary costs deferred in connection with loan originations as the first quarter of 2021 was impacted by the high volume of PPP loan originations. The increase in other non-interest expense was primarily related to increases in advertising/promotions expense; professional services expense; travel, meals and entertainment; and a decrease in costs deferred as loan origination costs; among other things. The impact of the aforementioned items was partly offset by decreases in donations expense; sundry and other miscellaneous expenses; and amortization of deferred costs associated with loan commitments, among other things. The increase in net occupancy was primarily related to increases in repairs and maintenance/service contracts expense and depreciation on buildings and leasehold improvements, among other things, which were impacted, in part, by our expansion within the Houston and Dallas market areas. The increase in employee benefits expense was primarily related to increases in payroll taxes and 401(k) plan expense, among other things,

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partly offset by an increase in the net periodic benefit related to our defined benefit retirement plan. The increase in technology, furniture and equipment expense was primarily related to increases in cloud services expense and depreciation of furniture and equipment, among other things, partly offset by a decrease in software maintenance. The increase in deposit insurance expense was primarily related to an increase in total assets partly offset by a decrease in the assessment rate. See the analysis of these categories of non-interest expense included in the section captioned “Non-Interest Expense” included elsewhere in this discussion.

Frost Insurance Agency, which is included in the Banking operating segment, had gross commission revenues of $16.7 million during the three months ended March 31, 2022 compared to $17.4 million during the same period in 2021. The decrease in gross commission income was primarily related to a decrease in contingent income partly offset by an increase in commission income. The decrease in contingent income was primarily related to a decrease in performance related contingent payments due to low growth within the portfolio and a deterioration in the loss performance of insurance policies previously placed. The decrease in performance related contingent commissions was partly offset by an increase in contingent commissions received from various benefit plan insurance companies. The increase in commission income was primarily related to an increase in commercial lines property and casualty commissions, due to increases in business volumes and market rates, partly offset by a decrease in life insurance commissions, due to a decrease in business volumes. See the analysis of insurance commissions and fees included in the section captioned “Non-Interest Income” included elsewhere in this discussion.

Frost Wealth Advisors

Net income for the three months ended March 31, 2022 increased $2.3 million, or 28.1%, compared to the same period in 2021. The increase was primarily the result of a $3.6 million increase in non-interest income and a $214 thousand increase in net interest income partly offset by a $973 thousand increase in non-interest expense and a $601 thousand increase in income tax expense.

Net interest income for the three months ended March 31, 2022 increased $214 thousand, or 44.0%, compared to the same periods in 2021. The increase was primarily due to an increase in the average volume of funds provided by Frost Wealth Advisors and an increase in the average funds transfer prices allocated to such funds. See the analysis of net interest income included in the section captioned “Net Interest Income” included elsewhere in this discussion.

Non-interest income for the three months ended March 31, 2022 increased $3.6 million, or 9.1%, compared to the same periods in 2021. The increase was primarily due to an increase in trust and investment management fees and, to a lesser extent, an increase in other charges, commissions and fees. Trust and investment management fee income is the most significant income component for Frost Wealth Advisors. Investment management fees are the most significant component of trust and investment management fees, making up approximately 81.6% of total trust and investment management fees for the first three months of 2022. The increase in trust and investment management fees during the comparable periods was primarily due to increases in investment management fees; oil and gas fees; and real estate fees. The increase in investment management fees was primarily related to higher average equity valuations as well as an increase in the number of accounts. Oil and gas fees were impacted by increases in oil and gas prices. The increase in real estate fees was primarily related to an increase in transaction volume. The increases in other charges, commissions and fees was primarily related to an increase in income from the sale of mutual funds partly offset by a decrease in income from the placement of money market accounts. See the analysis of trust and investment management fees and other charges, commissions and fees included in the section captioned “Non-Interest Income” included elsewhere in this discussion.

Non-interest expense for the three months ended March 31, 2022 increased $1.0 million, or 3.3%, compared to the same period in 2021. The increase was primarily due to increases in salaries and wages and employee benefits expense partly offset by a decrease in other non-interest expense. The increase in salaries and wages was primarily due to increases in incentive compensation and commission expense, and to a lesser extent, an increase in salaries. The increase in employee benefits expense was primarily related to increases in payroll taxes, 401(k) plan expense and medical insurance expense, among other things, partly offset by an increase in the net periodic benefit related to our defined benefit retirement plan. The decrease in other non-interest expense was primarily related to a decrease in the corporate overhead expense allocation partly offset by increases in research and platform fees; professional services expense; and travel, meals and entertainment, among other things.

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Non-Banks

The Non-Banks operating segment had a net loss of $2.5 million during the three months ended March 31, 2022, compared to a net loss of $1.6 million during the same period in 2021. The increase in the net loss was primarily due to decreases in other non-interest income and the net income tax benefit combined with increases in other non-interest expense and net interest expense. The decrease in other non-interest income was partly due to a decrease in mineral interest income as the related mineral interest assets were donated to the Frost Charitable Foundation during the third quarter of 2021. The decrease in other non-interest income was also negatively impacted by a decrease in the gains on sales of assets. The net income tax benefit in 2022 was impacted by the aforementioned donation of mineral interest assets during the third quarter of 2021 due to the elimination of certain related tax deductions. The increase in other non-interest expense was primarily due to increases in professional service expense and travel, meals and entertainment. The decrease in net interest expense was primarily related to an increase in the average rate paid on our long term borrowings partly offset by the redemption, during the fourth quarter of 2021, of $13.4 million of junior subordinated deferrable interest debentures issued to WNB Capital Trust I.

Income Taxes

During the three months ended March 31, 2022, we recognized income tax expense of $12.6 million, for an effective tax rate of 11.3%, compared to $7.9 million, for an effective tax rate of 6.4%, for the same period in 2021. The effective income tax rates differed from the U.S. statutory federal income tax rate of 21% during 2022 and 2021 primarily due to the effect of tax-exempt income from loans, securities and life insurance policies and the income tax effects associated with stock-based compensation, among other things, and their relative proportion to total pre-tax net income. The increase in the effective tax rate during 2022 was primarily related to an increase in projected pre-tax net income and, to a lesser extent, a decrease in discrete tax benefits associated with stock-based compensation.

Average Balance Sheet

Average assets totaled $50.3 billion for the three months ended March 31, 2022 representing an increase of $7.8 billion, or 18.3%, compared to average assets for the same period in 2021. Earning assets increased $7.5 billion, or 18.9%, during the first three months of 2022 compared to the same period in 2021. The increase in earning assets was primarily related to a $5.0 billion increase in average taxable securities and a $3.9 billion increase in average interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) partly offset by a $1.3 billion decrease in average loans. Average deposits increased $7.6 billion, or 21.3%, during the first three months of 2022 compared to the same period in 2021. Growth in average deposits was related to increased customer balances as well as new customer accounts. The increase included a $2.7 billion increase in non-interest bearing deposits and a $4.9 billion increase in interest-bearing deposit accounts. Average non-interest bearing deposits made up 41.8% and 43.2% of average total deposits during the first three months of 2022 and 2021, respectively.

Loans

Details of our loan portfolio are presented in Note 3 - Loans in the accompanying notes to consolidated financial statements included elsewhere in this report. Loans increased $206.1 million, or 1.3%, from $16.3 billion at December 31, 2021 to $16.5 billion at March 31, 2022. As further discussed below, during the second quarter of 2020, we began originating loans to qualified small businesses under the Paycheck Protection Program (“PPP”) administered by the SBA under the provisions of the CARES Act. Excluding PPP loans, total loans would have otherwise increased $427.4 million, or 2.7%, from $15.9 billion at December 31, 2021 to $16.3 billion at March 31, 2022. The majority of our loan portfolio is comprised of commercial and industrial loans, energy loans, and real estate loans. Real estate loans include both commercial and consumer balances. Selected details related to our loan portfolio segments are presented below. Refer to our 2021 Form 10-K for a more detailed discussion of our loan origination and risk management processes.

Commercial and Industrial. Commercial and industrial loans increased $219.2 million, or 4.1%, from $5.4 billion at December 31, 2021 to $5.6 billion at March 31, 2022. Our commercial and industrial loans are a diverse group of loans to small, medium and large businesses. The purpose of these loans varies from supporting seasonal working capital needs to term financing of equipment. While some short-term loans may be made on an unsecured basis, most are secured by the assets being financed with collateral margins that are consistent with our loan policy guidelines. The commercial and industrial loan portfolio also includes commercial leases and purchased shared national credits ("SNC"s).

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Energy. Energy loans include loans to entities and individuals that are engaged in various energy-related activities including (i) the development and production of oil or natural gas, (ii) providing oil and gas field servicing, (iii) providing energy-related transportation services, (iv) providing equipment to support oil and gas drilling, (v) refining petrochemicals, or (vi) trading oil, gas and related commodities. Energy loans decreased $41.2 million, or 3.8%, from $1.1 billion at December 31, 2021 to $1.0 billion at March 31, 2022. We have recently made efforts to reduce our exposure to energy loans. Nonetheless energy loans remain our largest industry concentration totaling 6.3% of total loans (also 6.3% excluding PPP loans) at March 31, 2022, down from 6.6% of total loans (6.8% excluding PPP loans) at December 31, 2021. The average loan size, the significance of the portfolio and the specialized nature of the energy industry requires a highly prescriptive underwriting policy. Exceptions to this policy are rarely granted. Due to the large borrowing requirements of this customer base, the energy loan portfolio includes participations and SNCs.

Purchased Shared National Credits. Purchased shared national credits are participations purchased from upstream financial organizations and tend to be larger in size than our originated portfolio. Our purchased SNC portfolio totaled $705.6 million at March 31, 2022, increasing $7.2 million, or 1.0%, from $698.4 million at December 31, 2021. At March 31, 2022, 25.4% of outstanding purchased SNCs were related to the construction industry while 23.2% were related to the energy industry, 15.6% were related to the financial services industry and 13.6% were related to the real estate management industry. The remaining purchased SNCs were diversified throughout various other industries, with no other single industry exceeding 10% of the total purchased SNC portfolio. Additionally, almost all of the outstanding balance of purchased SNCs was included in the energy and commercial and industrial portfolio, with the remainder included in the real estate categories. SNC participations are originated in the normal course of business to meet the needs of our customers. As a matter of policy, we generally only participate in SNCs for companies headquartered in or which have significant operations within our market areas. In addition, we must have direct access to the company’s management, an existing banking relationship or the expectation of broadening the relationship with other banking products and services within the following 12 to 24 months. SNCs are reviewed at least quarterly for credit quality and business development successes.

Commercial Real Estate. Commercial real estate loans increased $221.8 million, or 2.9%, from $7.6 billion at December 31, 2021 to $7.8 billion at March 31, 2022. Commercial real estate loans represented 84.5% of total real estate loans at March 31, 2022 compared to 84.3% at December 31, 2021. The majority of our commercial real estate loan portfolio consists of commercial real estate mortgages, which includes both permanent and intermediate term loans. These loans are viewed primarily as cash flow loans and secondarily as loans secured by real estate. Consequently, these loans must undergo the analysis and underwriting process of a commercial and industrial loan, as well as that of a real estate loan. At March 31, 2022, approximately 48.8% of the outstanding principal balance of our commercial real estate loans were secured by owner-occupied properties.

Consumer Real Estate and Other Consumer Loans. The consumer loan portfolio, including all consumer real estate and consumer installment loans, totaled $1.9 billion at both March 31, 2022 and December 31, 2021. Consumer real estate loans increased $22.8 million, or 1.6%, from December 31, 2021. Combined, home equity loans and lines of credit made up 60.5% and 59.8% of the consumer real estate loan total at March 31, 2022 and December 31, 2021, respectively. We offer home equity loans up to 80% of the estimated value of the personal residence of the borrower, less the value of existing mortgages and home improvement loans. We have not generally originated 1-4 family mortgage loans since 2000; however, from time to time, we invested in such loans to meet the needs of our customers or for other regulatory compliance purposes. Nonetheless, we expect to begin regular production of 1-4 family mortgage loans for portfolio investment purposes in the second half of 2022. Consumer and other loans increased $4.8 million, or 1.0%, from December 31, 2021. The consumer and other loan portfolio primarily consists of automobile loans, overdrafts, unsecured revolving credit products, personal loans secured by cash and cash equivalents and other similar types of credit facilities.

Paycheck Protection Program. We have originated loans to qualified small businesses under the PPP administered by the SBA under the provisions of the CARES Act. Loans covered by the PPP may be eligible for loan forgiveness for certain costs incurred related to payroll, group health care benefit costs and qualifying mortgage, rent and utility payments. The remaining loan balance after forgiveness of any amounts is still fully guaranteed by the SBA. Refer to the 2021 Form 10-K for additional details.

During the three months ended March 31, 2022, we recognized approximately $2.6 million in PPP loan related deferred processing fees (net of amortization of related deferred origination costs) as a yield adjustment and this amount is included in interest income on loans. During the three months ended March 31, 2021, we recognized approximately $23.5 million in PPP loan related deferred net processing fees. As a result of the inclusion of these net fees in interest income, the average yields on PPP loans were 4.45% during the three months ended March 31, 2022, and 4.39% during the three months ended March 31, 2021 compared to the stated interest rate of 1.0% on these loans. PPP related deferred processing fees and deferred origination costs are not expected to significantly impact interest income on loans in future periods.

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Accruing Past Due Loans. Accruing past due loans are presented in the following table. Also see Note 3 - Loans in the accompanying notes to consolidated financial statements included elsewhere in this report.

			Accruing Loans 30-89 Days Past Due				Accruing Loans 90 or More Days Past Due				Total Accruing Past Due Loans
	Total Loans		Amount		Percent of Loans in Category		Amount		Percent of Loans in Category		Amount		Percent of Loans in Category
March 31, 2022
Commercial and industrial	$	5,584,117	$	12,043	0.22	%	$	4,166	0.07	%	$	16,209	0.29	%
Energy	1,036,579		—		—		287		0.03		287		0.03
Paycheck Protection Program	207,669		671		0.32		8,377		4.03		9,048		4.35
Commercial real estate:
Buildings, land and other	6,376,521		18,527		0.29		1,046		0.02		19,573		0.31
Construction	1,421,878		1,988		0.14		—		—		1,988		0.14
Consumer real estate	1,433,625		4,150		0.29		2,103		0.15		6,253		0.44
Consumer and other	482,148		6,393		1.33		593		0.12		6,986		1.45
Total	$	16,542,537	$	43,772	0.26		$	16,572	0.10		$	60,344	0.36
Excluding PPP loans	$	16,334,868	$	43,101	0.26		$	8,195	0.05		$	51,296	0.31
December 31, 2021
Commercial and industrial	$	5,364,954	$	29,491	0.55	%	$	7,802	0.15	%	$	37,293	0.70	%
Energy	1,077,792		1,353		0.13		215		0.02		1,568		0.15
Paycheck Protection Program	428,882		4,979		1.16		18,766		4.38		23,745		5.54
Commercial real estate:
Buildings, land and other	6,272,339		37,033		0.59		8,687		0.14		45,720		0.73
Construction	1,304,271		188		0.01		—		—		188		0.01
Consumer real estate	1,410,790		4,866		0.34		2,177		0.15		7,043		0.49
Consumer and other	477,369		4,185		0.88		1,076		0.23		5,261		1.11
Total	$	16,336,397	$	82,095	0.50		$	38,723	0.24		$	120,818	0.74
Excluding PPP loans	$	15,907,515	$	77,116	0.48		$	19,957	0.13		$	97,073	0.61

Accruing past due loans at March 31, 2022 decreased $60.5 million compared to December 31, 2021. The decrease was primarily related to decreases in past due non-construction related commercial real estate loans (down $26.1 million), past due commercial and industrial loans (down $21.1 million) and past due PPP loans (down $14.7 million). PPP loans are fully guaranteed by the SBA and we expect to collect all amounts due related to these loans. Excluding PPP loans, accruing past due loans decreased $45.8 million.

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Non-Accrual Loans. Non-accrual loans are presented in the table below. Also see in Note 3 - Loans in the accompanying notes to consolidated financial statements included elsewhere in this report.

	March 31, 2022							December 31, 2021
			Non-Accrual Loans							Non-Accrual Loans
	Total Loans		Amount			Percent of Loans in Category		Total Loans		Amount			Percent of Loans in Category
Commercial and industrial	$	5,584,117	$	16,693		0.30	%	$	5,364,954	$	22,582		0.42	%
Energy	1,036,579		12,271			1.18		1,077,792		14,433			1.34
Paycheck Protection Program	207,669		—			—		428,882		—			—
Commercial real estate:
Buildings, land and other	6,376,521		19,003			0.30		6,272,339		15,297			0.24
Construction	1,421,878		583			0.04		1,304,271		948			0.07
Consumer real estate	1,433,625		416			0.03		1,410,790		440			0.03
Consumer and other	482,148		—			—		477,369		13			—
Total	$	16,542,537	$	48,966		0.30		$	16,336,397	$	53,713		0.33
Excluding PPP loans	$	16,334,868	$	48,966		0.30		$	15,907,515	$	53,713		0.34
Allowance for credit losses on loans			$	246,835						$	248,666
Ratio of allowance for credit losses on loans to non-accrual loans			504.09		%					462.95		%

Non-accrual loans at March 31, 2022 decreased $4.7 million from December 31, 2021 primarily due to a decrease in non-accrual commercial and industrial loans and energy loans partly offset by an increase in commercial real estate loans. The decreases in commercial were primarily related to principal payments, loans returning to accrual and charge offs.

Generally, loans are placed on non-accrual status if principal or interest payments become 90 days past due and/or management deems the collectibility of the principal and/or interest to be in question, as well as when required by regulatory requirements. Once interest accruals are discontinued, accrued but uncollected interest is charged to current year operations. Subsequent receipts on non-accrual loans are recorded as a reduction of principal, and interest income is recorded only after principal recovery is reasonably assured. Classification of a loan as non-accrual does not preclude the ultimate collection of loan principal or interest. There were no non-accrual commercial and industrial loans in excess of $5.0 million at March 31, 2022 or December 31, 2021. Non-accrual energy loans included one credit relationship in excess of $5 million totaling $8.2 million at March 31, 2022. This credit relationship was previously reported as non-accrual with an aggregate balance of $9.6 million at December 31, 2021. The decrease in the aggregate balance of this credit relationship was related to principal payments made by the borrower. Non-accrual real estate loans primarily consist of land development, 1-4 family residential construction credit relationships and loans secured by office buildings and religious facilities. Non-accrual commercial real estate loans included one credit relationship in excess of $5.0 million totaling $5.8 million at March 31, 2022 while there were no non-accrual commercial real estate loans in excess of $5.0 million at December 31, 2021.

Allowance for Credit Losses

In the case of loans and securities, allowances for credit losses are contra-asset valuation accounts, calculated in accordance with Accounting Standards Codification (“ASC”) Topic 326 (“ASC 326”) Financial Instruments - Credit Losses, that are deducted from the amortized cost basis of these assets to present the net amount expected to be collected. In the case of off-balance-sheet credit exposures, the allowance for credit losses is a liability account, calculated in accordance with ASC 326, reported as a component of accrued interest payable and other liabilities in our consolidated balance sheets. The amount of each allowance account represents management's best estimate of current expected credit losses (“CECL”) on these financial instruments considering available information, from internal and external sources, relevant to assessing exposure to credit loss over the contractual term of the instrument. Relevant available information includes historical credit loss experience, current conditions and reasonable and supportable forecasts. While historical credit loss experience provides the basis for the estimation of expected credit losses, adjustments to historical loss information may be made for differences in current portfolio-specific risk characteristics, environmental conditions or other relevant factors. While management utilizes its best judgment and information available, the ultimate adequacy of our allowance accounts is dependent upon a variety of factors beyond our control, including the performance of our portfolios, the economy, changes in interest rates and the view of the regulatory authorities toward classification of assets. See our 2021 Form 10-K for additional information regarding our accounting policies related to credit losses.

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Allowance for Credit Losses - Loans. The table below provides, as of the dates indicated, an allocation of the allowance for loan losses by loan portfolio segment; however, allocation of a portion of the allowance to one segment does not preclude its availability to absorb losses in other segments.

	Amount of Allowance Allocated		Percent of Loans in Each Category to Total Loans		Total Loans		Ratio of Allowance Allocated to Loans in Each Category
March 31, 2022
Commercial and industrial	$	87,026	33.8	%	$	5,584,117	1.56	%
Energy	15,422		6.3		1,036,579		1.49
Paycheck Protection Program	—		1.3		207,669		—
Commercial real estate	128,954		47.1		7,798,399		1.65
Consumer real estate	6,359		8.6		1,433,625		0.44
Consumer and other	9,074		2.9		482,148		1.88
Total	$	246,835	100.0	%	$	16,542,537	1.49
Excluding PPP loans	$	246,835			$	16,334,868	1.51	%
December 31, 2021
Commercial and industrial	$	72,091	32.9	%	$	5,364,954	1.34	%
Energy	17,217		6.6		1,077,792		1.60
Paycheck Protection Program	—		2.6		428,882		—
Commercial real estate	144,936		46.4		7,576,610		1.91
Consumer real estate	6,585		8.6		1,410,790		0.47
Consumer and other	7,837		2.9		477,369		1.64
Total	$	248,666	100.0	%	$	16,336,397	1.52
Excluding PPP loans	$	248,666			$	15,907,515	1.56

The allowance allocated to commercial and industrial loans totaled $87.0 million, or 1.56% of total commercial and industrial loans, at March 31, 2022 increasing $14.9 million, or 20.7%, compared to $72.1 million, or 1.34% of total commercial and industrial loans on December 31, 2021. Modeled expected credit losses decreased $311 thousand while Q-Factor and other qualitative adjustments related to commercial and industrial loans increased $19.3 million. Specific allocations for commercial and industrial loans that were evaluated for expected credit losses on an individual basis decreased $4.1 million from $10.5 million at December 31, 2021 to $6.5 million at March 31, 2022. The decrease in specific allocations for commercial and industrial loans was related to principal payments received and the recognition of charge-offs.

The allowance allocated to energy loans totaled $15.4 million, or 1.49% of total energy loans, at March 31, 2022 decreasing $1.8 million, or 10.4%, compared to $17.2 million, or 1.60% of total energy loans on December 31, 2021. Modeled expected credit losses related to energy loans decreased $392 thousand while Q-Factor and other qualitative adjustments related to energy loans decreased $1.1 million. Specific allocations for energy loans that were evaluated for expected credit losses on an individual basis totaled $5.2 million at March 31, 2022 decreasing $289 thousand compared to $5.5 million on December 31, 2021.

The allowance allocated to commercial real estate loans totaled $129.0 million, or 1.65% of total commercial real estate loans, at March 31, 2022 decreasing $16.0 million, or 11.0%, compared to $144.9 million, or 1.91% of total commercial real estate loans on December 31, 2021. Modeled expected credit losses related to commercial real estate loans increased $434 thousand while Q-Factor and other qualitative adjustments related to commercial real estate loans decreased $16.3 million. Specific allocations for commercial real estate loans that were evaluated for expected credit losses on an individual basis decreased from $400 thousand on December 31, 2021 to $326 thousand at March 31, 2022.

The allowance allocated to consumer real estate loans totaled $6.4 million, or 0.44% of total consumer real estate loans, at March 31, 2022 decreasing $226 thousand, or 3.4%, compared to $6.6 million, or 0.47% of total consumer real estate loans on December 31, 2021. Modeled expected credit losses related to consumer real estate loans decreased $224 thousand while Q-Factor and other qualitative adjustments related to consumer real estate loans decreased $2 thousand.

The allowance allocated to consumer loans totaled $9.1 million, or 1.88% of total consumer loans, at March 31, 2022 increasing $1.2 million, or 15.8%, compared to $7.8 million, or 1.64% of total consumer loans, on December 31, 2021. Modeled expected credit losses related to consumer loans increased $1.2 million while Q-Factor and other qualitative adjustments related to consumer loans did not fluctuate.

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As more fully described in our 2021 Form 10-K, we measure expected credit losses over the life of each loan utilizing a combination of models which measure probability of default and loss given default, among other things. The measurement of expected credit losses is impacted by loan/borrower attributes and certain macroeconomic variables. Models are adjusted to reflect current impact of certain macroeconomic variables as well as their expected changes over a reasonable and supportable forecast period.

In estimating expected credit losses as of March 31, 2022, we utilized the Moody’s Analytics March 2022 Consensus Scenario (the “March 2022 Consensus Scenario”) to forecast the macroeconomic variables used in our models. The March 2022 Consensus Scenario was based on the review of a variety of surveys of baseline forecasts of the U.S. economy. The March 2022 Consensus Scenario projections included, among other things, (i) U.S. Nominal Gross Domestic Product annualized quarterly growth rate of 8.7% in the second quarter of 2022, followed by average annualized quarterly growth rates of 4.4% during 2022 and 4.6% through the end of the forecast period in the first quarter of 2024; (ii) U.S. unemployment rate of 3.7% in the second quarter of 2022 and remaining fairly flat through the end of the forecast period where it is projected to be 3.6% in the first quarter of 2024; (iii) Texas unemployment rate of 4.0% in the second quarter of 2022 and improving to 3.7% by the end of the forecast in the first quarter of 2024; (iv) projected average 10 year Treasury rate of 2.08% in the second quarter of 2022, increasing to average projected rates of 2.15% during the remainder of 2022 and 2.33% through the end of the forecast period in the first quarter of 2024.

In estimating expected credit losses as of December 31, 2021, we utilized the Moody’s Analytics December 2021 Consensus Scenario (the “December 2021 Consensus Scenario”) to forecast the macroeconomic variables used in our models. The December 2021 Consensus Scenario was based on the review of a variety of surveys of baseline forecasts of the U.S. economy. The December 2021 Consensus Scenario projections included, among other things, (i) U.S. Nominal Gross Domestic Product annualized quarterly growth rate of 6.4% in the first quarter of 2022, followed by annualized quarterly growth rates in the range of 3.8% to 5.4% during the remainder of 2022 and an average annualized growth rate of 4.8% through the end of the forecast period in the fourth quarter of 2023; (ii) U.S. unemployment rate of 4.3% in the first quarter of 2022 improving to 3.7% by the end of the forecast period in the fourth quarter of 2023 with Texas unemployment rates slightly higher at those dates; and (iii) projected average 10 year Treasury rate of 1.59% in the first quarter of 2022, increasing to average projected rates of 1.75% during the remainder of 2022 and 2.10% in 2023.

The overall loan portfolio, excluding PPP loans which are fully guaranteed by the SBA, as of March 31, 2022 increased $427.4 million, or 2.7%, compared to December 31, 2021. This increase included a $221.8 million, or 2.9%, increase in commercial real estate loans, a $219.2 million, or 4.1%, increase in commercial and industrial loans, a $22.8 million, or 1.6%, increase in consumer real estate loans and a $4.8 million, or 1.0%, increase in consumer and other loans partly offset by a $41.2 million, or 3.8%, decrease in energy loans.

The weighted average risk grade for commercial and industrial loans increased to 6.34 at March 31, 2022 compared to 6.22 at December 31, 2021. This increase was primarily due to an increase in the weighted-average risk grade of pass-grade commercial and industrial loans to 6.18 at March 31, 2022 from 6.01 at December 31, 2021. Commercial and industrial loans graded “watch” and “special mention” (risk grades 9 and 10) decreased $48.1 million during the first three months of 2021 while classified commercial and industrial loans decreased $3.3 million. Classified loans consist of loans having a risk grade of 11, 12 or 13. The weighted-average risk grade for energy loans decreased to 5.89 at March 31, 2022 from 6.06 at December 31, 2021. The decrease in the weighted average risk grade was primarily related to a $27.6 million decrease in energy loans graded “watch” and “special mention” (risk grades 9 and 10) and an $4.5 million decrease in classified energy loans. Pass grade energy loans decreased $9.1 million and the weighted-average risk grade of pass grade energy loans decreased slightly from 5.78 at December 31, 2021 to 5.71 at March 31, 2022. The weighted average risk grade for commercial real estate loans decreased to 7.11 at March 31, 2022 from 7.19 at December 31, 2021. Pass grade commercial real estate loans increased $361.0 million while commercial real estate loans graded as “watch” and “special mention” decreased $107.0 million and classified commercial real estate loans decreased $32.2 million.

As noted above, our credit loss models utilized the economic forecasts in the Moody's March 2022 Consensus Scenario for our estimated expected credit losses as of March 31, 2022 and the Moody's December 2021 Consensus Scenario for our estimate of expected credit losses as of December 31, 2021. We qualitatively adjusted the model results based on these scenarios for various risk factors that are not considered within our modeling processes but are nonetheless relevant in assessing the expected credit losses within our loan pools. These qualitative factor (“Q-Factor”) adjustments are discussed below.

Q-Factor adjustments are based upon management judgment and current assessment as to the impact of risks related to changes in lending policies and procedures; economic and business conditions; loan portfolio attributes and credit concentrations; and external factors, among other things, that are not already captured within the modeling inputs, assumptions and other processes. Management assesses the potential impact of such items within a range of severely negative impact to positive impact and adjusts the modeled expected credit loss by an aggregate adjustment percentage based upon the assessment.

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As a result of this assessment as of March 31, 2022, modeled expected credit losses were adjusted upwards by a weighted-average Q-Factor adjustment of approximately 1.9%, resulting in a $1.4 million total adjustment, down from approximately 2.3% at December 31, 2021, which resulted in a $1.8 million total adjustment. The weighted-average Q-Factor adjustment at March 31, 2022 was based on a limited negative expected impact on our commercial loan portfolios related to changes in loan portfolio concentrations; a negative expected impact associated with national, regional and local economic and business conditions and developments that affect the collectability of loans; a severely negative expected impact from other risk factors associated with our commercial real estate construction and land loan portfolios, particularly the risks related to expected extensions; and no impact to changes lending policies procedures and underwriting standards; loan portfolio attributes; changes in risk grades; changes in the volumes and severity of loan delinquencies; and adverse classifications and potential deterioration of collateral values.

We have also provided additional qualitative adjustments, or management overlays, as of March 31, 2022 as management believes there are still significant risks impacting certain categories of our loan portfolio. Q-Factor and other qualitative adjustments as of March 31, 2022 are detailed in the table below.

	Q-Factor Adjustment		Model Overlays		Office Building Overlays		Down-Side Scenario Overlay		Post-Pandemic Overlays		Credit Concentration Overlays		Consumer Overlay		Total
Commercial and industrial	$	700	$	—	$	—	$	27,218	$	1,543	$	4,455	$	—	$	33,916
Energy	90		—		—		—		—		4,170		—		4,260
Commercial real estate:
Owner occupied	160		35,546		—		—		1,206		1,306		—		38,218
Non-owner occupied	14		12,107		28,956		—		10,582		689		—		52,348
Construction	393		12,949		6,675		—		231		704		—		20,952
Consumer real estate	63		—		—		—		—		—		—		63
Consumer	8		—		—		—		—		—		1,432		1,440
Total	$	1,428	$	60,602	$	35,631	$	27,218	$	13,562	$	11,324	$	1,432	$	151,197

Model overlays are qualitative adjustments to address the effect of unusually large positive changes in certain economic variables used by our commercial real estate credit loss models. These adjustments are determined based upon minimum reserve ratios for our commercial real estate - owner occupied, commercial real estate - non-owner occupied and commercial real estate - construction loan portfolios.

Office building overlays are qualitative adjustments to address longer-term concerns over the utilization of commercial office space which could impact the long-term performance of some types of office properties within our commercial real estate loan portfolio. These adjustments are determined based upon minimum reserve ratios for loans within our commercial real estate - non-owner occupied and commercial real estate - construction loan portfolios that have risk grades of 8 or worse.

The down-side scenario overlay is a qualitative adjustment for our commercial and industrial loan portfolio to address the significant risk of economic recession as a result of inflation; labor shortages; disruption in financial markets and global supply chains; further oil price volatility; and the current or anticipated impact of military conflict, including the current war between Russia and Ukraine, terrorism or other geopolitical events. Factors such as these are outside of our control but nonetheless affect customer income levels and could alter anticipated customer behavior, including borrowing, repayment, investment and deposit practices. To determine this qualitative adjustment, we use an alternative, more pessimistic economic scenario to forecast the macroeconomic variables used in our models. As of March 31, 2022, we used the Moody’s Analytics March 2022 S3 Alternative Scenario Downside - 90th Percentile (the “March 2022 S3 Scenario”). In modeling expected credit losses using this scenario, we also assume each loan within our modeled loan pools is downgraded by one risk grade level. The qualitative adjustment is based upon the amount by which the alternative scenario modeling results exceed those of the primary scenario used in estimating credit loss expense, adjusted based upon management's assessment of the probability that this more pessimistic economic scenario will occur.

Post-pandemic overlays are qualitative adjustments to address elevated risk associated with certain industries and not addressed in other qualitative adjustments, due to the lingering, post-pandemic effects of COVID-19, particularly the impact of behavioral changes in business travel and entertainment, labor and staffing shortages, and inflation. These adjustments are determined based upon minimum reserve ratios, stratified by risk grade, for loans to customers within the hotel, restaurant and entertainment industries. These industries were considered the most at risk based upon a comprehensive review of the financial condition and overall outlook of the borrowers within these portfolios. We are continuing to monitor these customers closely as they have been, and are expected to continue to be, more significantly impacted by the lingering, post-pandemic effects of COVID-19.

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Credit concentration overlays are qualitative adjustments based upon statistical analysis to address relationship exposure concentrations within our loan portfolio. Variations in loan portfolio concentrations over time cause expected credit losses within our existing portfolio to differ from historical loss experience. Given that the allowance for credit losses on loans reflects expected credit losses within our loan portfolio and the fact that these expected credit losses are uncertain as to nature, timing and amount, management believes that segments with higher concentration risk are more likely to experience a high loss event. Due to the fact that a significant portion of our loan portfolio is concentrated in large credit relationships and because of large, concentrated credit losses in recent years, management made the qualitative adjustments detailed in the table above to address the risk associated with such a relationship deteriorating to a loss event.

The consumer overlay is a qualitative adjustment for our consumer and other loan portfolio to address the risk associated with the level of unsecured loans within this portfolio and other risk factors. Unsecured consumer loans have an elevated risk of loss in times of economic stress as these loans lack a secondary source of repayment in the form of hard collateral. This adjustment was determined by analyzing our consumer loan charge-off trends as well as those of the general banking industry. Management deemed it appropriate to consider an additional overlay to the modeled forecasted losses for the unsecured consumer portfolio.

As of December 31, 2021, we provided qualitative adjustments, as detailed in the table below. Though largely similar to those described above, further information regarding these qualitative adjustments is provided in our 2021 Form 10-K.

	Q-Factor Adjustment		Model Overlays		Office Building Overlays		Small Business Overlay		COVID-19 Related Overlays		Credit Concentration Overlays		Consumer Overlay		Total
Commercial and industrial	$	939	$	—	$	—	$	3,956	$	4,715	$	4,999	$	—	$	14,609
Energy	127		—		—		—		—		5,247		—		5,374
Commercial real estate:
Owner occupied	198		31,806		—		—		7,397		1,320		—		40,721
Non-owner occupied	45		7,762		27,860		—		30,940		731		—		67,338
Construction	383		11,212		5,544		—		2,151		511		—		19,801
Consumer real estate	65		—		—		—		—		—		—		65
Consumer	8		—		—		—		—		—		1,432		1,440
Total	$	1,765	$	50,780	$	33,404	$	3,956	$	45,203	$	12,808	$	1,432	$	149,348

Additional information related to credit loss expense and net (charge-offs) recoveries is presented in the table below. Also see Note 3 - Loans in the accompanying notes to consolidated financial statements included elsewhere in this report.

	Credit Loss Expense (Benefit)		Net (Charge-Offs) Recoveries		Average Loans		Ratio of Annualized Net (Charge-Offs) Recoveries to Average Loans
Three months ended:
March 31, 2022
Commercial and industrial	$	17,561	$	(2,626)	$	5,466,467	(0.19)	%
Energy	(2,044)		249		1,055,021		0.10
Paycheck Protection Program	—		—		302,431		—
Commercial real estate	(15,609)		(373)		7,666,754		(0.02)
Consumer real estate	(26)		(200)		1,422,077		(0.06)
Consumer and other	4,582		(3,345)		473,708		(2.86)
Total	$	4,464	$	(6,295)	$	16,386,458	(0.16)
Excluding PPP loans	$	4,464	$	(6,295)	$	16,084,027	(0.16)
March 31, 2021
Commercial and industrial	$	(1,965)	$	(986)	$	4,816,537	(0.08)	%
Energy	(5,801)		(280)		1,169,168		(0.10)
Paycheck Protection Program	—		—		2,831,085		—
Commercial real estate	8,922		626		7,072,932		0.04
Consumer real estate	(2,722)		432		1,328,590		0.13
Consumer and other	1,566		(1,711)		465,605		(1.49)
Total	$	—	$	(1,919)	$	17,683,917	(0.04)
Excluding PPP loans	$	—	$	(1,919)	$	14,852,832	(0.05)

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We recorded a net credit loss expense related to loans totaling $4.5 million for the three months ended March 31, 2022 while no net credit loss expense or benefit was recognized during the same period in 2021. Net credit loss expense/benefit for each portfolio segment reflects the amount needed to adjust the allowance for credit losses allocated to that segment to the level of expected credit losses determined under our allowance methodology after net charge-offs have been recognized. The net credit loss expense related to loans during the first three months of 2022 primarily reflects increases in expected credit losses associated with commercial and industrial loans, primarily related to the down-side scenario overlay discussed above, and consumer and other loans, primarily related to an increase in modeled losses, as well as the level of net charge-offs associated with these loan portfolio segments. The impact of these items was partly offset by a decrease in expected credit losses associated with commercial real estate loans, primarily related to a decrease in expected credit losses related to certain pandemic impacted industries. The ratio of the allowance for credit losses on loans to total loans was 1.49% (1.51% excluding PPP loans) at March 31, 2022 compared to 1.52% (1.56% excluding PPP loans) at December 31, 2021. Management believes the recorded amount of the allowance for credit losses on loans is appropriate based upon management’s best estimate of current expected credit losses within the existing portfolio of loans. Should any of the factors considered by management in making this estimate change, our estimate of current expect credit losses could also change, which could affect the level of future credit loss expense related to loans.

Allowance for Credit Losses - Off-Balance-Sheet Credit Exposures. The allowance for credit losses on off-balance-sheet credit exposures totaled approximately $45.9 million and $50.3 million at March 31, 2022 and December 31, 2021, respectively. The level of the allowance for credit losses on off-balance-sheet credit exposures depends upon the volume of outstanding commitments, underlying risk grades, the expected utilization of available funds and forecasted economic conditions impacting our loan portfolio. Our policies and methodology used to estimate the allowance for credit losses on off-balance-sheet credit exposures are further described in our 2021 Form 10-K. We recognized a net credit loss benefit related to off-balance-sheet credit exposures totaling $4.5 million during the three months ended March 31, 2022 compared to a net credit loss expense of $65 thousand during the same period in 2021. The credit loss benefit during the first three months of 2022 was partly impacted by the upgrade of a large credit commitment within our SNC portfolio.

Capital and Liquidity

Capital. Shareholders’ equity totaled $3.8 billion and $4.4 billion at March 31, 2022 and December 31, 2021, respectively. The decrease was primarily related to the accumulated other comprehensive income/loss component of shareholders’ equity which decreased to a net, after-tax, unrealized loss of $371.8 million at March 31, 2022 from a net, after-tax unrealized gain of $347.3 million at December 31, 2021. The change was primarily due to a $719.5 million net, after-tax, decrease in the fair value of securities available for sale. Other uses of capital during the three months ended March 31, 2022 included $50.1 million of dividends paid on preferred and common stock and $996 thousand of treasury stock purchases. Sources of capital during the three months ended March 31, 2022 included net income of $99.1 million, $5.7 million in proceeds from stock option exercises and $2.1 million related to stock-based compensation.

Under the Basel III Capital Rules, we have elected to opt-out of the requirement to include most components of accumulated other comprehensive income in regulatory capital. Accordingly, amounts reported as accumulated other comprehensive income/loss do not increase or reduce regulatory capital and are not included in the calculation of our regulatory capital ratios. In connection with the adoption of ASC 326 on January 1, 2020, we also elected to exclude, for a transitional period, the effects of credit loss accounting under CECL in the calculation of our regulatory capital and regulatory capital ratios. Regulatory agencies for banks and bank holding companies utilize capital guidelines designed to measure capital and take into consideration the risk inherent in both on-balance-sheet and off-balance-sheet items. See Note 7 - Capital and Regulatory Matters in the accompanying notes to consolidated financial statements included elsewhere in this report.

We paid a quarterly dividend of $0.75 per common share during the first quarter of 2022 and a quarterly dividend of $0.72 per common share during the first quarter of 2021. These dividend amounts equate to a common stock dividend payout ratio of 49.7% and 40.5% during the first three months of 2022 and 2021, respectively. Our ability to declare or pay dividends on, or purchase, redeem or otherwise acquire, shares of our capital stock may be impacted by certain restrictions described in Note 7 - Capital and Regulatory Matters in the accompanying notes to consolidated financial statements included elsewhere in this report.

Stock Repurchase Plans. From time to time, our board of directors has authorized stock repurchase plans. In general, stock repurchase plans allow us to proactively manage our capital position and return excess capital to shareholders. Shares purchased under such plans also provide us with shares of common stock necessary to satisfy obligations related to stock compensation awards. On January 26, 2022 our board of directors authorized a $100.0 million stock repurchase program, allowing us to repurchase shares of our common stock over a one-year period from time to time at various prices in the open market or through private transactions. No shares have been repurchased under this plan or under a prior plan during the reported periods.

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See Note 7 - Capital and Regulatory Matters in the accompanying notes to consolidated financial statements and Part II, Item 2 - Unregistered Sales of Equity Securities and Use of Proceeds, each included elsewhere in this report.

Liquidity. As more fully discussed in our 2021 Form 10-K, our liquidity position is continuously monitored and adjustments are made to the balance between sources and uses of funds as deemed appropriate. Liquidity risk management is an important element in our asset/liability management process. We regularly model liquidity stress scenarios to assess potential liquidity outflows or funding problems resulting from economic disruptions, volatility in the financial markets, unexpected credit events or other significant occurrences deemed problematic by management. These scenarios are incorporated into our contingency funding plan, which provides the basis for the identification of our liquidity needs. Our principal source of funding has been our customer deposits, supplemented by our short-term and long-term borrowings as well as maturities of securities and loan amortization. As of March 31, 2022, we had approximately $13.4 billion held in an interest-bearing account at the Federal Reserve. We also have the ability to borrow funds as a member of the Federal Home Loan Bank (“FHLB”). As of March 31, 2022, based upon available, pledgeable collateral, our total borrowing capacity with the FHLB was approximately $3.2 billion. Furthermore, at March 31, 2022, we had approximately $12.8 billion in securities that were unencumbered by a pledge and could be used to support additional borrowings through repurchase agreements or the Federal Reserve discount window, as needed.

Since Cullen/Frost is a holding company and does not conduct operations, its primary sources of liquidity are dividends upstreamed from Frost Bank and borrowings from outside sources. Banking regulations may limit the amount of dividends that may be paid by Frost Bank. See Note 7 - Capital and Regulatory Matters in the accompanying notes to consolidated financial statements included elsewhere in this report regarding such dividends. At March 31, 2022, Cullen/Frost had liquid assets, including cash and resell agreements, totaling $476.0 million.

Accounting Standards Updates

See Note 17 - Accounting Standards Updates in the accompanying notes to consolidated financial statements included elsewhere in this report for details of recently issued accounting pronouncements and their expected impact on our financial statements.

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Item 3. Quantitative and Qualitative Disclosures About Market Risk

The disclosures set forth in this item are qualified by the section captioned “Forward-Looking Statements and Factors that Could Affect Future Results” included in Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations of this report and other cautionary statements set forth elsewhere in this report.

Refer to the discussion of market risks included in Item 7A. Quantitative and Qualitative Disclosures About Market Risk in the 2021 Form 10-K. There has been no significant change in the types of market risks we face since December 31, 2021.

We utilize an earnings simulation model as the primary quantitative tool in measuring the amount of interest rate risk associated with changing market rates. The model quantifies the effects of various interest rate scenarios on projected net interest income and net income over the next 12 months. The model measures the impact on net interest income relative to a flat-rate case scenario of hypothetical fluctuations in interest rates over the next 12 months. These simulations incorporate assumptions regarding balance sheet growth and mix, pricing and the repricing and maturity characteristics of the existing and projected balance sheet. The impact of interest rate derivatives, such as interest rate swaps, caps and floors, is also included in the model. Other interest rate-related risks such as prepayment, basis and option risk are also considered.

For modeling purposes, as of March 31, 2022, the model simulations projected that 100 and 200 basis point ratable increases in interest rates would result in positive variances in net interest income of 2.1% and 5.8%, respectively, relative to the flat-rate case over the next 12 months, while a 50 basis point ratable decrease in interest rates would result in a negative variance in net interest income of 3.7% relative to the flat-rate case over the next 12 months. For modeling purposes, as of December 31, 2021, the model simulations projected that 100 and 200 basis point ratable increases in interest rates would result in positive variances in net interest income of 2.8% and 7.1%, respectively, relative to the flat-rate case over the next 12 months, while a 25 basis point ratable decrease in interest rates would result in a negative variance in net interest income of 3.0% relative to the flat-rate case over the next 12 months. Both the March 31, 2022 and December 31, 2021 model simulations for increased interest rates were impacted by the assumption, for modeling purposes, that we will begin to pay interest on commercial demand deposits (those not already receiving an earnings credit rate) in the first and second quarters of 2022, respectively, as further discussed below. The likelihood of a decrease in interest rates beyond 50 basis points as of March 31, 2022 and 25 basis points as of December 31, 2021 was considered remote given prevailing interest rate levels.

The model simulations as of March 31, 2022 indicate that our projected balance sheet is less asset sensitive in comparison to our balance sheet as of December 31, 2021. The decreased asset sensitivity was partly due to a decrease in the relative proportion of interest-bearing deposits (primarily amounts held in an interest-bearing account at the Federal Reserve) and federal funds sold to projected average interest-earning assets. Interest-bearing deposits and federal funds sold are more immediately impacted by changes in interest rates in comparison to our other categories of earning assets. Additionally, the positive impact of increasing interest rates was partly mitigated due to an increase in the relative proportion of interest-bearing deposit liabilities to total deposits as of March 31, 2022 compared to December 31, 2021, resulting in a higher projected cost of deposits.

We do not currently pay interest on a significant portion of our commercial demand deposits. Any interest rate that would ultimately be paid on these commercial demand deposits would likely depend upon a variety of factors, some of which are beyond our control. Our modeling simulations as of March 31, 2022 and December 31, 2021 assume a slightly aggressive pricing structure with regards to interest payments on commercial demand deposits (those not already receiving an earnings credit) with interest payments assumed to begin in the second and first quarters of 2022, respectively. This pricing structure on commercial demand deposits assumes a deposit pricing beta of 25%. The pricing beta is a measure of how much deposit rates reprice, up or down, given a defined change in market rates.

As of March 31, 2022, the effects of a 200 basis point increase and a 50 basis point decrease in interest rates on our derivative holdings would not result in a significant variance in our net interest income.

The effects of hypothetical fluctuations in interest rates on our securities classified as “trading” under ASC Topic 320, “Investments—Debt and Equity Securities,” are not significant, and, as such, separate quantitative disclosure is not presented.

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Item 4. Controls and Procedures

As of the end of the period covered by this Quarterly Report on Form 10-Q, an evaluation was carried out by management, with the participation of its Chief Executive Officer and Chief Financial Officer, of the effectiveness of our disclosure controls and procedures (as defined in Rule 13a-15(e) under the Securities Exchange Act of 1934). Based upon that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that the disclosure controls and procedures were effective as of the end of the period covered by this report. No change in our internal control over financial reporting (as defined in Rule 13a-15(f) under the Securities Exchange Act of 1934) occurred during the last fiscal quarter that materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

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Part II. Other Information

Item 1. Legal Proceedings

We are subject to various claims and legal actions that have arisen in the course of conducting business. Management does not expect the ultimate disposition of these matters to have a material adverse impact on our financial statements.

Item 1A. Risk Factors

There has been no material change in the risk factors disclosed under Item 1A. of our 2021 Form 10-K.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

The following table provides information with respect to purchases we made or were made on our behalf or any “affiliated purchaser” (as defined in Rule 10b-18(a)(3) under the Securities Exchange Act of 1934), of our common stock during the three months ended March 31, 2022. Dollar amounts in thousands.

Period	Total Number of Shares Purchased		Average Price Paid Per Share		Total Number of Shares Purchased as Part of Publicly Announced Plan	Maximum Number of Shares (or Approximate Dollar Value) That May Yet Be Purchased Under the Plan at the End of the Period
January 1, 2022 to January 31, 2022	—		$	—	—	$	100,000
February 1, 2022 to February 28, 2022	—		—		—	100,000
March 1, 2022 to March 31, 2022	7,459	(1)	133.54		—	100,000
Total	7,459				—

(1)Repurchases made in connection with the vesting of certain share awards.

Item 3. Defaults Upon Senior Securities

None.

Item 4. Mine Safety Disclosures

None.

Item 5. Other Information

None.

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Item 6. Exhibits

(a) Exhibits

Exhibit Number	Description
31.1	Rule 13a-14(a) Certification of the Corporation's Chief Executive Officer
31.2	Rule 13a-14(a) Certification of the Corporation's Chief Financial Officer
32.1(1)	Section 1350 Certification of the Corporation's Chief Executive Officer
32.2(1)	Section 1350 Certification of the Corporation's Chief Financial Officer
101.INS(2)	Inline XBRL Instance Document
101.SCH	Inline XBRL Taxonomy Extension Schema Document
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document
101.LAB	InlineXBRL Taxonomy Extension Label Linkbase Document
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document
104(3)	Cover Page Interactive Data File

(1)This exhibit shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liability of that section, and shall not be deemed to be incorporated by reference into any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

(2)The instance document does not appear in the interactive data file because its XBRL tags are embedded within the Inline XBRL document.

(3)Formatted as Inline XBRL and contained within the Inline XBRL Instance Document in Exhibit 101.

59

Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		Cullen/Frost Bankers, Inc.
		(Registrant)
Date:	April 28, 2022	By:	/s/ Jerry Salinas
			Jerry Salinas
			Group Executive Vice President
			and Chief Financial Officer
			(Duly Authorized Officer, Principal Financial
			Officer and Principal Accounting Officer)

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EX-31.1

Exhibit 31.1

Rule 13a-14(a) Certification

of the Corporation’s Chief Executive Officer

I, Phillip D. Green, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q of Cullen/Frost Bankers, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of registrant’s board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

April 28, 2022

/s/ Phillip D. Green

Phillip D. Green

Chief Executive Officer

EX-31.2

Exhibit 31.2

Rule 13a-14(a) Certification

of the Corporation’s Chief Financial Officer

I, Jerry Salinas, certify that:

1.I have reviewed this Quarterly Report on Form 10-Q of Cullen/Frost Bankers, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of registrant’s board of directors (or persons performing the equivalent functions):

(a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

April 28, 2022

/s/ Jerry Salinas

Jerry Salinas

Group Executive Vice President and Chief Financial Officer

EX-32.1

Exhibit 32.1

Section 1350 Certification of the

Corporation’s Chief Executive Officer

Pursuant to Subsections (a) and (b) of Section 1350 of Chapter 63 of Title 18 of the United States Code in accordance with Section 906 of the Sarbanes-Oxley Act of 2002, the undersigned, Phillip D. Green, Chief Executive Officer, of Cullen/Frost Bankers, Inc. (the “Corporation”), hereby certifies, to his knowledge, that the Corporation’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2022 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and that the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Corporation.

/s/ Phillip D. Green	April 28, 2022
Phillip D. Green

The forgoing certification is being furnished solely pursuant to Subsections (a) and (b) of Section 1350 of Chapter 63 of Title 18 of the United States Code in accordance with Section 906 of the Sarbanes-Oxley Act of 2002 and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liability of that section, and shall not be deemed to be incorporated by reference into any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

EX-32.2

Exhibit 32.2

Section 1350 Certification of the

Corporation’s Chief Financial Officer

Pursuant to Subsections (a) and (b) of Section 1350 of Chapter 63 of Title 18 of the United States Code in accordance with Section 906 of the Sarbanes-Oxley Act of 2002, the undersigned, Jerry Salinas, Chief Financial Officer, of Cullen/Frost Bankers, Inc. (the “Corporation”), hereby certifies, to his knowledge, that the Corporation’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2022 (the “Report”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, and that the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Corporation.

/s/ Jerry Salinas	April 28, 2022
Jerry Salinas

The forgoing certification is being furnished solely pursuant to Subsections (a) and (b) of Section 1350 of Chapter 63 of Title 18 of the United States Code in accordance with Section 906 of the Sarbanes-Oxley Act of 2002 and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, or otherwise subject to the liability of that section, and shall not be deemed to be incorporated by reference into any filing under the Securities Act of 1933 or the Securities Exchange Act of 1934.

XML

Document and Entity Information - $ / shares	3 Months Ended
	Mar. 31, 2022	Apr. 21, 2022	Dec. 31, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-13221
Entity Registrant Name	Cullen/Frost Bankers, Inc.
Entity Incorporation, State or Country Code	TX
Entity Tax Identification Number	74-1751768
Entity Address, Address Line One	111 W. Houston Street,
Entity Address, City or Town	San Antonio,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	78205
City Area Code	(210)
Local Phone Number	220-4011
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		64,097,017
Common stock, par value	$ 0.01		$ 0.01
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Entity Central Index Key	0000039263
Current Fiscal Year End Date	--12-31
Common Stock [Member] | NEW YORK STOCK EXCHANGE, INC. [Member]
Entity Information [Line Items]
Title of 12(b) Security	Common Stock, $.01 Par Value
Trading Symbol	CFR
Security Exchange Name	NYSE
Series B Preferred Stock [Member] | NEW YORK STOCK EXCHANGE, INC. [Member]
Entity Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing a 1/40th interest in a share of 4.450% Non-Cumulative Perpetual Preferred Stock, Series B
Trading Symbol	CFR.PrB
Security Exchange Name	NYSE

XML

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Cash and due from banks	$ 772,095	$ 555,778
Interest-bearing deposits	13,684,988	15,985,244
Federal funds sold	0	34,075
Resell agreements	0	7,903
Total cash and cash equivalents	14,457,083	16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at March 31, 2022 and $158 at December 31, 2021	1,665,465	1,749,179
Securities available for sale, at estimated fair value	16,184,539	13,924,628
Trading account securities	29,518	25,162
Loans, net of unearned discounts	16,542,537	16,336,397
Less: Allowance for credit losses on loans	(246,835)	(248,666)
Net loans	16,295,702	16,087,731
Premises and equipment, net	1,046,410	1,050,331
Goodwill	654,952	654,952
Other intangible assets, net	720	866
Cash surrender value of life insurance policies	189,471	190,139
Accrued interest receivable and other assets	772,191	612,502
Total assets	51,296,051	50,878,490
Liabilities:
Non-interest-bearing demand deposits	18,114,430	18,423,018
Interest-bearing deposits	26,316,499	24,272,678
Total deposits	44,430,929	42,695,696
Federal funds purchased	35,200	25,925
Repurchase agreements	1,842,618	2,740,799
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,026	123,011
Subordinated notes, net of unamortized issuance costs	99,217	99,178
Accrued interest payable and other liabilities	988,769	754,326
Total liabilities	47,519,759	46,438,935
Shareholders’ Equity:
Preferred stock, par value $0.01 per share; 10,000,000 shares authorized; 150,000 Series B shares ($1,000 liquidation preference) issued at March 31, 2022 and December 31, 2021	145,452	145,452
Common stock, par value $0.01 per share; 210,000,000 shares authorized; 64,236,306 shares issued at March 31, 2022 and December 31, 2021	642	642
Additional paid-in capital	1,012,033	1,009,921
Retained earnings	3,002,642	2,956,966
Accumulated other comprehensive income (loss), net of tax	(371,790)	347,318
Treasury stock, at cost; 142,099 shares at March 31, 2022 and 250,070 shares at December 31, 2021	(12,687)	(20,744)
Total shareholders’ equity	3,776,292	4,439,555
Total liabilities and shareholders’ equity	$ 51,296,051	$ 50,878,490

XML

Consolidated Balance Sheets (Parenthetical) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Securities, held-to-maturity, allowance for credit loss	$ 158,000	$ 158,000
Preferred stock liquidation preference value	$ 150,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	210,000,000	210,000,000
Common stock, shares issued	64,236,306	64,236,306
Treasury stock, shares	142,099	250,070
Series B Preferred Stock [Member]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	150,000	150,000
Preferred stock liquidation preference value	$ 1,000	$ 1,000

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Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Interest income:
Loans, including fees	$ 149,977	$ 167,483
Securities:
Taxable	43,058	20,028
Tax-exempt	56,866	56,663
Interest-bearing deposits	6,343	2,433
Federal funds sold	13	3
Resell agreements	4	1
Total interest income	256,261	246,611
Interest expense:
Deposits	4,912	3,517
Federal funds purchased	12	8
Repurchase agreements	518	395
Junior subordinated deferrable interest debentures	584	646
Subordinated notes	1,164	1,164
Total interest expense	7,190	5,730
Net interest income	249,071	240,881
Credit loss expense	0	63
Net interest income after credit loss expense	249,071	240,818
Non-interest income:
Trust and investment management fees	38,656	35,314
Service charges on deposit accounts	22,740	19,993
Insurance commissions and fees	16,608	17,313
Interchange and card transaction fees	4,226	4,093
Other charges, commissions and fees	9,627	8,304
Net gain (loss) on securities transactions	0	0
Other	9,533	8,219
Total non-interest income	101,390	93,236
Non-interest expense:
Salaries and wages	111,329	93,458
Employee benefits	24,220	22,536
Net occupancy	27,411	26,051
Technology, furniture and equipment	29,157	28,016
Deposit insurance	3,633	2,928
Intangible amortization	146	202
Other	42,836	36,951
Total non-interest expense	238,732	210,142
Income before income taxes	111,729	123,912
Income taxes	12,627	7,897
Net income	99,102	116,015
Preferred stock dividends	1,669	2,151
Net income available to common shareholders	$ 97,433	$ 113,864
Earnings per common share:
Basic	$ 1.51	$ 1.78
Diluted	$ 1.50	$ 1.77

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Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Net income	$ 99,102	$ 116,015
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	(910,795)	(159,779)
Change in net unrealized gain on securities transferred to held to maturity	(209)	(259)
Reclassification adjustment for net (gains) losses included in net income	0	0
Total securities available for sale and transferred securities, before tax amount	(911,004)	(160,038)
Defined-benefit post-retirement benefit plans:
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit)	741	1,529
Total defined-benefit post-retirement benefit plans	741	1,529
Other comprehensive income (loss), before tax	(910,263)	(158,509)
Deferred tax expense (benefit)	(191,155)	(33,287)
Other comprehensive income (loss), net of tax	(719,108)	(125,222)
Comprehensive income (loss)	$ (620,006)	$ (9,207)

XML

Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]
Total shareholders’ equity at beginning of period at Dec. 31, 2020	$ 4,293,016	$ 145,452	$ 642	$ 997,168	$ 2,750,723	$ 512,970	$ (113,939)
Net income	116,015				116,015
Other comprehensive income (loss)	(125,222)					(125,222)
Stock option exercises/stock unit conversions (115,430 shares YTD in 2022 and 513,824 shares YTD in 2021)	29,397				(21,342)		50,739
Stock compensation expense recognized in earnings	2,526			2,526
Purchase of treasury stock (7,459 shares YTD in 2022 and 11,625 shares YTD in 2021)	(1,288)						(1,288)
Treasury stock issued to the 401(k) stock purchase plan (18,555 shares YTD in 2021 )	1,749				(57)		1,806
Cash dividends – preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depository share YTD in 2022 and $14.34 per share which is equivalent to approximately $0.36 per depository share YTD in 2021)	(2,151)				(2,151)
Cash dividends – common stock ($0.75 per share YTD in 2022 and $0.72 per share YTD in 2021)	(46,124)				(46,124)
Total shareholders’ equity at end of period at Mar. 31, 2021	4,267,918	145,452	642	999,694	2,797,064	387,748	(62,682)
Total shareholders’ equity at beginning of period at Dec. 31, 2021	4,439,555	145,452	642	1,009,921	2,956,966	347,318	(20,744)
Net income	99,102				99,102
Other comprehensive income (loss)	(719,108)					(719,108)
Stock option exercises/stock unit conversions (115,430 shares YTD in 2022 and 513,824 shares YTD in 2021)	5,739				(3,314)		9,053
Stock compensation expense recognized in earnings	2,112			2,112
Purchase of treasury stock (7,459 shares YTD in 2022 and 11,625 shares YTD in 2021)	(996)						(996)
Treasury stock issued to the 401(k) stock purchase plan (18,555 shares YTD in 2021 )	0
Cash dividends – preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depository share YTD in 2022 and $14.34 per share which is equivalent to approximately $0.36 per depository share YTD in 2021)	(1,669)				(1,669)
Cash dividends – common stock ($0.75 per share YTD in 2022 and $0.72 per share YTD in 2021)	(48,443)				(48,443)
Total shareholders’ equity at end of period at Mar. 31, 2022	$ 3,776,292	$ 145,452	$ 642	$ 1,012,033	$ 3,002,642	$ (371,790)	$ (12,687)

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Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Stockholders' Equity [Abstract]
Stock option exercise/stock unit conversions (115,430 shares YTD during 2022 and 513,824 shares YTD during 2021)	115,430	513,824
Purchase of treasury stock (7,459 shares during 2022 and 11,625 shares during 2021)	7,459	11,625
Treasury stock issued to the 401(k) stock purchase plan (18,555 shares YTD in 2021 )		18,555
Cash dividend - preferred stock (Approximately $11.13 per share YTD in 2022 and $14.34 per share YTD during 2021)	$ 11.13	$ 14.34
Cash dividend - Preferred Stock Dividends equivalent Per depositary Share Declared ($0.28 YTD during 2022 and $0.36 YTD during 2021)	0.28	0.36
Cash dividends - common stock ($0.75 per share YTD during 2022 and $0.72 per share YTD during 2021)	$ 0.75	$ 0.72

XML

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Activities:
Net income	$ 99,102	$ 116,015
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	0	63
Deferred tax expense (benefit)	(432)	4,172
Accretion of loan discounts	(2,945)	(3,425)
Securities premium amortization (discount accretion), net	27,654	30,598
Net (gain) loss on securities transactions	0	0
Depreciation and amortization	17,551	16,941
Net (gain) loss on sale/write-down of assets/foreclosed assets	130	(134)
Stock-based compensation	2,112	2,526
Net tax benefit from stock-based compensation	1,244	3,136
Earnings on life insurance policies	(533)	(740)
Net change in:
Trading account securities	139	(2,153)
Lease right-of-use assets	5,970	5,889
Accrued interest receivable and other assets	(55,232)	73,164
Accrued interest payable and other liabilities	238,065	(26,287)
Net cash from operating activities	332,825	219,765
Investing Activities:
Securities held-to-maturity - Purchases	(31,545)	0
Securities held to maturity: Maturities, calls and principal repayments	111,211	120,029
Securities available for sale:
Purchases	(3,356,279)	(455,091)
Sales	0	0
Maturities, calls and principal repayments	236,032	351,612
Net change in loans	(209,490)	(406,836)
Benefits received on life insurance policies	1,201	968
Proceeds from sales of premises and equipment	1	3
Purchases of premises and equipment	(12,374)	(12,814)
Proceeds from sales of repossessed properties	1,543	100
Net cash from investing activities	(3,259,700)	(402,029)
Financing Activities:
Net change in deposits	1,735,233	1,909,419
Net change in short-term borrowings	(888,906)	(193,573)
Proceeds from stock option exercises	5,739	29,397
Purchase of treasury stock	(996)	(1,288)
Cash dividends paid on preferred stock	(1,669)	(2,151)
Cash dividends paid on common stock	(48,443)	(46,124)
Net cash from financing activities	800,958	1,695,680
Net change in cash and cash equivalents	(2,125,917)	1,513,416
Cash and cash equivalents at beginning of period	16,583,000	10,288,853
Cash and cash equivalents at end of period	$ 14,457,083	$ 11,802,269

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Significant Accounting Policies

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Significant Accounting Policies

Significant Accounting Policies

Nature of Operations. Cullen/Frost Bankers, Inc. (“Cullen/Frost”) is a financial holding company and a bank holding company headquartered in San Antonio, Texas that provides, through its subsidiaries, a broad array of products and services throughout numerous Texas markets. The terms “Cullen/Frost,” “the Corporation,” “we,” “us” and “our” mean Cullen/Frost Bankers, Inc. and its subsidiaries, when appropriate. In addition to general commercial and consumer banking, other products and services offered include trust and investment management, insurance, brokerage, mutual funds, leasing, treasury management, capital markets advisory and item processing.

Basis of Presentation. The consolidated financial statements in this Quarterly Report on Form 10-Q include the accounts of Cullen/Frost and all other entities in which Cullen/Frost has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. The accounting and financial reporting policies we follow conform, in all material respects, to accounting principles generally accepted in the United States and to general practices within the financial services industry.

The consolidated financial statements in this Quarterly Report on Form 10-Q have not been audited by an independent registered public accounting firm, but in the opinion of management, reflect all adjustments necessary for a fair presentation of our financial position and results of operations. All such adjustments were of a normal and recurring nature. The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q adopted by the Securities and Exchange Commission (“SEC”). Accordingly, the financial statements do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements and should be read in conjunction with our consolidated financial statements, and notes thereto, for the year ended December 31, 2021, included in our Annual Report on Form 10-K filed with the SEC on February 4, 2022 (the “2021 Form 10-K”). Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year or any future period.

Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. The allowance for loan losses and the fair values of financial instruments and the status of contingencies are particularly subject to change.

Cash Flow Reporting. Additional cash flow information was as follows:

	Three Months Ended March 31,
	2022		2021
Cash paid for interest	$	8,069	$	9,719
Cash paid for income taxes	—		—
Significant non-cash transactions:
Unsettled securities transactions	78,769		21,957
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities	4,013		1,326
Treasury stock issued to 401(k) stock purchase plan	—		1,749

Accounting Changes, Reclassifications and Restatements. Certain items in prior financial statements have been reclassified to conform to the current presentation.

XML

Securities

3 Months Ended

Mar. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Securities

Securities

Securities - Held to Maturity. A summary of the amortized cost, fair value and allowance for credit losses related to securities held to maturity as of March 31, 2022 and December 31, 2021 is presented below.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Allowance for Credit Losses		Net Carrying Amount
March 31, 2022
Residential mortgage-backed securities	$	526,969	$	—	$	17,519	$	509,450	$	—	$	526,969
States and political subdivisions	1,137,154		3,622		11,717		1,129,059		(158)		1,136,996
Other	1,500		—		16		1,484		—		1,500
Total	$	1,665,623	$	3,622	$	29,252	$	1,639,993	$	(158)	$	1,665,465
December 31, 2021
Residential mortgage-backed securities	$	527,264	$	18,766	$	—	$	546,030	$	—	$	527,264
States and political subdivisions	1,220,573		41,141		101		1,261,613		(158)		1,220,415
Other	1,500		—		—		1,500		—		1,500
Total	$	1,749,337	$	59,907	$	101	$	1,809,143	$	(158)	$	1,749,179

All mortgage-backed securities included in the above table were issued by U.S. government agencies and corporations. The carrying value of held-to-maturity securities pledged to secure public funds, trust deposits, repurchase agreements and for other purposes, as required or permitted by law was $252.0 million and $642.3 million at March 31, 2022 and December 31, 2021, respectively. Accrued interest receivable on held-to-maturity securities totaled $10.0 million and $18.4 million at March 31, 2022 and December 31, 2021, respectively and is included in accrued interest receivable and other assets in the accompanying consolidated balance sheets.

From time to time, we have reclassified certain securities from available for sale to held to maturity. The net unamortized, unrealized gain remaining on transferred securities included in accumulated other comprehensive income in the accompanying balance sheet totaled $2.3 million ($1.8 million, net of tax) at March 31, 2022 and $2.5 million ($2.0 million, net of tax) at December 31, 2021. This amount will be amortized out of accumulated other comprehensive income over the remaining life of the underlying securities as an adjustment of the yield on those securities.

The following table summarizes Moody's and/or Standard & Poor's bond ratings for our portfolio of held-to-maturity securities issued by States and political subdivisions and other securities as of March 31, 2022 and December 31, 2021:

	States and Political Subdivisions
	Not Guaranteed or Pre-Refunded		Guaranteed by the Texas PSF		Pre-Refunded		Total		Other Securities
March 31, 2022
Aaa/AAA	$	91,034	$	467,039	$	471,183	$	1,029,256	$	—
Aa/AA	107,898		—		—		107,898		—
Not rated	—		—		—		—		1,500
Total	$	198,932	$	467,039	$	471,183	$	1,137,154	$	1,500
December 31, 2021
Aaa/AAA	$	92,379	$	460,648	$	563,251	$	1,116,278	$	—
Aa/AA	104,295		—		—		104,295		—
Not rated	—		—		—		—		1,500
Total	$	196,674	$	460,648	$	563,251	$	1,220,573	$	1,500

The following table details activity in the allowance for credit losses on held-to-maturity securities during the three months ended March 31, 2022 and 2021.

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	158	$	160
Credit loss expense (benefit)	—		(2)
Ending balance	$	158	$	158

Securities - Available for Sale. A summary of the amortized cost, fair value and allowance for credit losses related to securities available for sale as of March 31, 2022 and December 31, 2021 is presented below.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Allowance for Credit Losses		Estimated Fair Value
March 31, 2022
U.S. Treasury	$	3,658,506	$	1,883	$	152,643	$	—	$	3,507,746
Residential mortgage-backed securities	5,696,906		7,246		328,113		—		5,376,039
States and political subdivisions	7,218,821		135,206		95,634		—		7,258,393
Other	42,361		—		—		—		42,361
Total	$	16,616,594	$	144,335	$	576,390	$	—	$	16,184,539
December 31, 2021
U.S. Treasury	$	2,165,702	$	23,333	$	9,602	$	—	$	2,179,433
Residential mortgage-backed securities	4,059,692		31,662		25,089		—		4,066,265
States and political subdivisions	7,178,135		463,810		5,374		—		7,636,571
Other	42,359		—		—		—		42,359
Total	$	13,445,888	$	518,805	$	40,065	$	—	$	13,924,628

All mortgage-backed securities included in the above table were issued by U.S. government agencies and corporations. At March 31, 2022, all of the securities in our available for sale municipal bond portfolio were issued by the State of Texas or political subdivisions or agencies within the State of Texas, of which approximately 75.7% are either guaranteed by the PSF or have been pre-refunded. Securities with limited marketability, such as stock in the Federal Reserve Bank and the Federal Home Loan Bank, are carried at cost and are reported as other available for sale securities in the table above. The carrying value of available-for-sale securities pledged to secure public funds, trust deposits, repurchase agreements and for other purposes, as required or permitted by law was $4.8 billion and $5.8 billion at March 31, 2022 and December 31, 2021, respectively. Accrued interest receivable on available-for-sale securities totaled $80.8 million and $120.5 million at March 31, 2022 and December 31, 2021, respectively, and is included in accrued interest receivable and other assets in the accompanying consolidated balance sheets.

The table below summarizes, as of March 31, 2022, securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded, aggregated by type of security and length of time in a continuous unrealized loss position.

	Less than 12 Months				More than 12 Months				Total
	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
U.S. Treasury	$	3,220,375	$	152,643	$	—	$	—	$	3,220,375	$	152,643
Residential mortgage-backed securities	4,583,657		286,421		402,940		41,692		4,986,597		328,113
States and political subdivisions	1,233,614		93,136		13,602		2,498		1,247,216		95,634
Total	$	9,037,646	$	532,200	$	416,542	$	44,190	$	9,454,188	$	576,390

As of March 31, 2022, no allowance for credit losses has been recognized on available for sale securities in an unrealized loss position as management does not believe any of the securities are impaired due to reasons of credit quality. This is based upon our analysis of the underlying risk characteristics, including credit ratings, and other qualitative factors related to our available for sale securities and in consideration of our historical credit loss experience and internal forecasts. The issuers of these securities continue to make timely principal and interest payments under the contractual terms of the securities. Furthermore, management does not have the intent to sell any of the securities classified as available for sale in the table above and believes that it is more likely than not that we will not have to sell any such securities before a recovery of cost. The

unrealized losses are due to increases in market interest rates over the yields available at the time the underlying securities were purchased. The fair value is expected to recover as the securities approach their maturity date or repricing date or if market yields for such investments decline.

Contractual Maturities. The following table summarizes the maturity distribution schedule of securities held to maturity and securities available for sale as of March 31, 2022. Mortgage-backed securities are included in maturity categories based on their stated maturity date. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. Other securities classified as available for sale include stock in the Federal Reserve Bank and the Federal Home Loan Bank, which have no maturity date. These securities have been included in the total column only.

	Within 1 Year		1 - 5 Years		5 - 10 Years		After 10 Years		Total
Held To Maturity
Amortized Cost
Residential mortgage-backed securities	$	16	$	—	$	514,842	$	12,111	$	526,969
States and political subdivisions	429,852		118,516		56,735		532,051		1,137,154
Other	—		1,500		—		—		1,500
Total	$	429,868	$	120,016	$	571,577	$	544,162	$	1,665,623
Estimated Fair Value
Residential mortgage-backed securities	$	16	$	—	$	498,078	$	11,356	$	509,450
States and political subdivisions	431,961		119,698		56,973		520,427		1,129,059
Other	—		1,484		—		—		1,484
Total	$	431,977	$	121,182	$	555,051	$	531,783	$	1,639,993
Available For Sale
Amortized Cost
U. S. Treasury	$	—	$	2,033,995	$	1,432,731	$	191,780	$	3,658,506
Residential mortgage-backed securities	102		12,917		19,060		5,664,827		5,696,906
States and political subdivisions	194,416		1,563,829		888,489		4,572,087		7,218,821
Other	—		—		—		—		42,361
Total	$	194,518	$	3,610,741	$	2,340,280	$	10,428,694	$	16,616,594
Estimated Fair Value
U. S. Treasury	$	—	$	1,978,865	$	1,350,553	$	178,328	$	3,507,746
Residential mortgage-backed securities	103		13,212		19,327		5,343,397		5,376,039
States and political subdivisions	197,231		1,603,985		899,602		4,557,575		7,258,393
Other	—		—		—		—		42,361
Total	$	197,334	$	3,596,062	$	2,269,482	$	10,079,300	$	16,184,539

Sales of Securities. No held to maturity or available for sale securities were sold during the three months ended March 31, 2022 or 2021.

Premiums and Discounts. Premium amortization and discount accretion included in interest income on securities was as follows:

	Three Months Ended March 31,
	2022		2021
Premium amortization	$	(29,060)	$	(31,235)
Discount accretion	1,406		637
Net (premium amortization) discount accretion	$	(27,654)	$	(30,598)

Trading Account Securities. Trading account securities, at estimated fair value, were as follows:

	March 31, 2022		December 31, 2021
U.S. Treasury	$	23,939	$	24,237
States and political subdivisions	5,579		925
Total	$	29,518	$	25,162

Net gains and losses on trading account securities were as follows:

	Three Months Ended March 31,
	2022		2021
Net gain on sales transactions	$	340	$	109
Net mark-to-market gains (losses)	(168)		(69)
Net gain (loss) on trading account securities	$	172	$	40

XML

Loans

3 Months Ended

Mar. 31, 2022

Receivables [Abstract]

Loans

Loans

Loans were as follows:

	March 31, 2022		December 31, 2021
Commercial and industrial	$	5,584,117	$	5,364,954
Energy:
Production	820,107		878,436
Service	113,708		105,901
Other	102,764		93,455
Total energy	1,036,579		1,077,792
Paycheck Protection Program	207,669		428,882
Commercial real estate:
Commercial mortgages	5,918,011		5,867,062
Construction	1,421,878		1,304,271
Land	458,510		405,277
Total commercial real estate	7,798,399		7,576,610
Consumer real estate:
Home equity loans	321,842		324,157
Home equity lines of credit	544,822		519,098
Other	566,961		567,535
Total consumer real estate	1,433,625		1,410,790
Total real estate	9,232,024		8,987,400
Consumer and other	482,148		477,369
Total loans	$	16,542,537	$	16,336,397

Concentrations of Credit. Most of our lending activity occurs within the State of Texas, including the four largest metropolitan areas of Austin, Dallas/Ft. Worth, Houston and San Antonio, as well as other markets. The majority of our loan portfolio consists of commercial and industrial and commercial real estate loans. As of March 31, 2022, there were no concentrations of loans related to any single industry in excess of 10% of total loans. The largest industry concentration was related to the energy industry, which totaled 6.3% of total loans (also 6.3% excluding PPP loans). Unfunded commitments to extend credit and standby letters of credit issued to customers in the energy industry totaled $862.2 million and $76.0 million, respectively, as of March 31, 2022.

Foreign Loans. We have U.S. dollar denominated loans and commitments to borrowers in Mexico. The outstanding balance of these loans and the unfunded amounts available under these commitments were not significant at March 31, 2022 or December 31, 2021.

Related Party Loans. In the ordinary course of business, we have granted loans to certain directors, executive officers and their affiliates (collectively referred to as “related parties”). Such loans totaled $346.5 million at March 31, 2022 and $350.5 million at December 31, 2021.

Accrued Interest Receivable. Accrued interest receivable on loans totaled $39.5 million and $40.0 million at March 31, 2022 and December 31, 2021, respectively and is included in accrued interest receivable and other assets in the accompany consolidated balance sheets.

Non-Accrual and Past Due Loans. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Loans are placed on non-accrual status when, in management’s opinion, the borrower may be unable to meet payment obligations as they become due, as well as when required by regulatory provisions.

Non-accrual loans, segregated by class of loans, were as follows:

	March 31, 2022				December 31, 2021
	Total Non-Accrual		Non-Accrual with No Credit Loss Allowance		Total Non-Accrual		Non-Accrual with No Credit Loss Allowance
Commercial and industrial	$	16,693	$	6,135	$	22,582	$	4,701
Energy	12,271		6,912		14,433		8,533
Paycheck Protection Program	—		—		—		—
Commercial real estate:
Buildings, land and other	19,003		17,005		15,297		13,817
Construction	583		583		948		—
Consumer real estate	416		114		440		138
Consumer and other	—		—		13		13
Total	$	48,966	$	30,749	$	53,713	$	27,202

The following table presents non-accrual loans as of March 31, 2022 by class and year of origination.

	2021		2020		2019		2018		2017		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Commercial and industrial	$	—	$	478	$	4,101	$	3,910	$	1,552	$	1,033	$	2,038	$	3,581	$	16,693
Energy	—		—		—		5,039		1,137		—		5,997		98		12,271
Paycheck Protection Program	—		—		—		—		—		—		—		—		—
Commercial real estate:
Buildings, land and other	—		8,407		296		1,199		394		2,932		—		5,775		19,003
Construction	—		—		583		—		—		—		—		—		583
Consumer real estate	—		—		—		—		—		390		—		26		416
Consumer and other	—		—		—		—		—		—		—		—		—
Total	$	—	$	8,885	$	4,980	$	10,148	$	3,083	$	4,355	$	8,035	$	9,480	$	48,966

Had non-accrual loans performed in accordance with their original contract terms, we would have recognized additional interest income, net of tax, of approximately $407 thousand for the three months ended March 31, 2022, and approximately $453 thousand for the three months ended March 31, 2021.

An age analysis of past due loans (including both accruing and non-accruing loans), segregated by class of loans, as of March 31, 2022 was as follows:

	Loans 30-89 Days Past Due		Loans 90 or More Days Past Due		Total Past Due Loans		Current Loans		Total Loans		Accruing Loans 90 or More Days Past Due
Commercial and industrial	$	13,016	$	8,042	$	21,058	$	5,563,059	$	5,584,117	$	4,166
Energy	—		6,382		6,382		1,030,197		1,036,579		287
Paycheck Protection Program	671		8,377		9,048		198,621		207,669		8,377
Commercial real estate:
Buildings, land and other	21,542		11,546		33,088		6,343,433		6,376,521		1,046
Construction	1,988		—		1,988		1,419,890		1,421,878		—
Consumer real estate	4,210		2,409		6,619		1,427,006		1,433,625		2,103
Consumer and other	6,393		593		6,986		475,162		482,148		593
Total	$	47,820	$	37,349	$	85,169	$	16,457,368	$	16,542,537	$	16,572

Troubled Debt Restructurings. There were no loans modified as troubled debt restructurings during the three months ended March 31, 2022 and 2021. Loan modifications are typically related to extending amortization periods, converting loans to interest only for a limited period of time, deferral of interest payments, waiver of certain covenants, consolidating notes and/or reducing collateral or interest rates. Modifications have not generally had a significant impact on our determination of the allowance for credit losses on loans. Information as of or for the three months ended March 31, 2022 and 2021 related to loans restructured during the last twelve months is set forth in the following table.

	March 31, 2022		March 31, 2021
Restructured loans past due in excess of 90 days at period-end:
Number of loans	2		2
Dollar amount of loans	$	572	$	1,392
Charge-offs of restructured loans:
Recognized on previously restructured loans	723		1,433

Credit Quality Indicators. As part of the on-going monitoring of the credit quality of our loan portfolio, management tracks certain credit quality indicators including trends related to (i) the weighted-average risk grade of commercial loans, (ii) the level of classified commercial loans, (iii) the delinquency status of consumer loans (iv) non-performing loans (see details above) and (vi) the general economic conditions in the State of Texas.

We utilize a risk grading matrix to assign a risk grade to each of our commercial loans. Loans are graded on a scale of 1 to 14. A description of the general characteristics of the 14 risk grades is set forth in our 2021 Form 10-K. We monitor portfolio credit quality by the weighted-average risk grade of each class of commercial loan. Individual relationship managers, under the oversight of credit administration, review updated financial information for all pass grade loans to reassess the risk grade on at least an annual basis. When a loan has a risk grade of 9, it is still considered a pass grade loan; however, it is considered to be on management’s “watch list,” where a significant risk-modifying action is anticipated in the near term. When a loan has a risk grade of 10 or higher, a special assets officer monitors the loan on an on-going basis.

The following tables present weighted-average risk grades for all commercial loans, by class and year of origination/renewal as of March 31, 2022. Paycheck Protection Program (“PPP”) loans are excluded as such loans are fully guaranteed by the Small Business Administration (“SBA”).

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial and industrial
Risk grades 1-8	$	836,152	$	894,663	$	592,780	$	305,667	$	160,622	$	243,869	$	2,255,878	$	44,778	$	5,334,409	6.18
Risk grade 9	4,702		34,513		6,562		11,434		21,841		8,319		54,008		4,721		146,100		9.00
Risk grade 10	3,500		22,084		6,527		1,039		4,007		578		13,899		1,198		52,832		10.00
Risk grade 11	—		1,926		6,672		9,679		1,697		2,200		5,958		5,951		34,083		11.00
Risk grade 12	—		478		2,644		3,510		1,488		619		941		2,015		11,695		12.00
Risk grade 13	—		—		1,457		400		64		414		1,097		1,566		4,998		13.00
	$	844,354	$	953,664	$	616,642	$	331,729	$	189,719	$	255,999	$	2,331,781	$	60,229	$	5,584,117	6.34
W/A risk grade	6.16		6.87		6.17		6.75		7.00		5.80		6.14		7.82		6.34
Energy
Risk grades 1-8	$	279,051	$	125,435	$	7,519	$	8,444	$	4,068	$	5,665	$	509,657	$	59,424	$	999,263	5.71
Risk grade 9	1,425		103		508		1,407		96		—		5,668		43		9,250		9.00
Risk grade 10	—		—		90		580		351		—		—		515		1,536		10.00
Risk grade 11	9,097		265		512		3,256		951		178		—		—		14,259		11.00
Risk grade 12	—		—		—		3,708		58		—		3,215		98		7,079		12.00
Risk grade 13	—		—		—		1,331		1,079		—		2,782		—		5,192		13.00
	$	289,573	$	125,803	$	8,629	$	18,726	$	6,603	$	5,843	$	521,322	$	60,080	$	1,036,579	5.89
W/A risk grade	6.36		5.77		7.73		9.34		9.24		7.16		5.41		6.31		5.89

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial real estate:
Buildings, land, other
Risk grades 1-8	$	607,883	$	1,554,611	$	1,113,230	$	809,206	$	498,477	$	1,057,840	$	72,704	$	96,924	$	5,810,875	6.89
Risk grade 9	6,163		20,766		108,943		53,448		23,459		45,034		5,516		2,618		265,947		9.00
Risk grade 10	46,125		22,716		7,310		66,821		24,539		57,602		—		—		225,113		10.00
Risk grade 11	—		260		1,293		7,328		6,788		36,699		3,215		—		55,583		11.00
Risk grade 12	—		8,081		296		1,199		394		2,932		—		5,775		18,677		12.00
Risk grade 13	—		326		—		—		—		—		—		—		326		13.00
	$	660,171	$	1,606,760	$	1,231,072	$	938,002	$	553,657	$	1,200,107	$	81,435	$	105,317	$	6,376,521	7.14
W/A risk grade	7.08		7.22		7.04		7.32		7.27		6.97		7.06		6.99		7.14
Construction
Risk grades 1-8	$	202,413	$	634,897	$	195,127	$	141,510	$	636	$	1,842	$	207,182	$	3,666	$	1,387,273	6.96
Risk grade 9	171		28,069		5,359		—		—		423		—		—		34,022		9.00
Risk grade 10	—		—		—		—		—		—		—		—		—		10.00
Risk grade 11	—		—		—		—		—		—		—		—		—		11.00
Risk grade 12	—		—		583		—		—		—		—		—		583		12.00
Risk grade 13	—		—		—		—		—		—		—		—		—		13.00
	$	202,584	$	662,966	$	201,069	$	141,510	$	636	$	2,265	$	207,182	$	3,666	$	1,421,878	7.01
W/A risk grade	6.83		7.28		6.38		7.98		6.22		7.17		6.28		8.00		7.01
Total commercial real estate	$	862,755	$	2,269,726	$	1,432,141	$	1,079,512	$	554,293	$	1,202,372	$	288,617	$	108,983	$	7,798,399	7.11
W/A risk grade	7.02		7.24		6.95		7.41		7.27		6.97		6.50		7.03		7.11

In the table above, certain energy loans are reported as 2022 originations and have risk grades of 11 or higher. These loans were, for the most part, first originated in various years prior to 2022 but were renewed in the current year.

The following tables present weighted average risk grades for all commercial loans by class as of December 31, 2021. Refer to our 2021 Form 10-K for details of these loans by year of origination/renewal.

	Commercial and Industrial			Energy			Commercial Real Estate - Buildings, Land and Other			Commercial Real Estate - Construction			Total Commercial Real Estate
	W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans
Risk grades 1-8	6.01	$	5,063,847	5.78	$	1,008,370	6.91	$	5,574,922	6.99	$	1,262,200	6.92	$	6,837,122
Risk grade 9	9.00	187,870		9.00	36,622		9.00	321,533		9.00	41,123		9.00	362,656
Risk grade 10	10.00	59,137		10.00	1,773		10.00	269,447		10.00	—		10.00	269,447
Risk grade 11	11.00	31,518		11.00	16,594		11.00	91,140		11.00	—		11.00	91,140
Risk grade 12	12.00	12,535		12.00	8,953		12.00	15,097		12.00	748		12.00	15,845
Risk grade 13	13.00	10,047		13.00	5,480		13.00	200		13.00	200		13.00	400
Total	6.22	$	5,364,954	6.06	$	1,077,792	7.22	$	6,272,339	7.06	$	1,304,271	7.19	$	7,576,610

Information about the payment status of consumer loans, segregated by portfolio segment and year of origination, as of March 31, 2022 was as follows:

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Consumer real estate:
Past due 30-89 days	$	—	$	303	$	55	$	465	$	309	$	1,587	$	60	$	1,431	$	4,210
Past due 90 or more days	—		—		4		—		297		854		1,004		250		2,409
Total past due	—		303		59		465		606		2,441		1,064		1,681		6,619
Current loans	51,321		322,814		225,921		86,664		48,481		149,677		533,182		8,946		1,427,006
Total	$	51,321	$	323,117	$	225,980	$	87,129	$	49,087	$	152,118	$	534,246	$	10,627	$	1,433,625
Consumer and other:
Past due 30-89 days	$	1,470	$	385	$	53	$	69	$	54	$	24	$	2,344	$	1,994	$	6,393
Past due 90 or more days	—		499		—		23		—		13		—		58		593
Total past due	1,470		884		53		92		54		37		2,344		2,052		6,986
Current loans	21,692		34,798		13,127		4,936		2,207		2,520		371,266		24,616		475,162
Total	$	23,162	$	35,682	$	13,180	$	5,028	$	2,261	$	2,557	$	373,610	$	26,668	$	482,148

Revolving loans that converted to term during the three months ended March 31, 2022 and 2021 were as follows:

	Three Months Ended March 31,
	2021		2020
Commercial and industrial	$	5,763	$	11,843
Energy	—		5,928
Commercial real estate:
Buildings, land and other	47		23,303
Construction	3,666		—
Consumer real estate	858		793
Consumer and other	4,222		3,861
Total	$	14,556	$	45,728

In assessing the general economic conditions in the State of Texas, management monitors and tracks the Texas Leading Index (“TLI”), which is produced by the Federal Reserve Bank of Dallas. The TLI, the components of which are more fully described in our 2021 Form 10-K, totaled 141.2 at March 31, 2022 and 135.9 at December 31, 2021. A higher TLI value implies more favorable economic conditions.

Allowance For Credit Losses - Loans. The allowance for credit losses on loans is a contra-asset valuation account, calculated in accordance with ASC 326, that is deducted from the amortized cost basis of loans to present the net amount expected to be collected. The amount of the allowance represents management's best estimate of current expected credit losses on loans considering available information, from internal and external sources, relevant to assessing collectibility over the loans' contractual terms, adjusted for expected prepayments when appropriate. Credit loss expense related to loans reflects the totality of actions taken on all loans for a particular period including any necessary increases or decreases in the allowance related to changes in credit loss expectations associated with specific loans or pools of loans. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged off. While management utilizes its best judgment and information available, the ultimate appropriateness of the allowance is dependent upon a variety of factors beyond our control, including the performance of our loan portfolio, the economy, changes in interest rates and the view of the regulatory authorities toward loan classifications. Our allowance methodology is more fully described in our 2021 Form 10-K.

The following table presents details of the allowance for credit losses on loans segregated by loan portfolio segment as of March 31, 2022 and December 31, 2021. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA.

March 31, 2022	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Modeled expected credit losses	$	46,635	$	5,971	$	17,110	$	6,260	$	7,634	$	83,610
Q-Factor and other qualitative adjustments	33,916		4,260		111,518		63		1,440		151,197
Specific allocations	6,475		5,191		326		36		—		12,028
Total	$	87,026	$	15,422	$	128,954	$	6,359	$	9,074	$	246,835
December 31, 2021
Modeled expected credit losses	$	46,946	$	6,363	$	16,676	$	6,484	$	6,397	$	82,866
Q-Factor and other qualitative adjustments	14,609		5,374		127,860		65		1,440		149,348
Specific allocations	10,536		5,480		400		36		—		16,452
Total	$	72,091	$	17,217	$	144,936	$	6,585	$	7,837	$	248,666

The following table details activity in the allowance for credit losses on loans by portfolio segment for the three months ended March 31, 2022 and 2021. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA.

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Three months ended:
March 31, 2022
Beginning balance	$	72,091	$	17,217	$	144,936	$	6,585	$	7,837	$	248,666
Credit loss expense (benefit)	17,561		(2,044)		(15,609)		(26)		4,582		4,464
Charge-offs	(3,455)		(371)		(702)		(231)		(5,771)		(10,530)
Recoveries	829		620		329		31		2,426		4,235
Net charge-offs	(2,626)		249		(373)		(200)		(3,345)		(6,295)
Ending balance	$	87,026	$	15,422	$	128,954	$	6,359	$	9,074	$	246,835
March 31, 2021
Beginning balance	$	73,843	$	39,553	$	134,892	$	7,926	$	6,963	$	263,177
Credit loss expense (benefit)	(1,965)		(5,801)		8,922		(2,722)		1,566		—
Charge-offs	(2,189)		(1,433)		—		(284)		(4,060)		(7,966)
Recoveries	1,203		1,153		626		716		2,349		6,047
Net charge-offs	(986)		(280)		626		432		(1,711)		(1,919)
Ending balance	$	70,892	$	33,472	$	144,440	$	5,636	$	6,818	$	261,258

The following table presents loans that were evaluated for expected credit losses on an individual basis and the related specific allocations, by loan portfolio segment as of March 31, 2022 and December 31, 2021.

	March 31, 2022				December 31, 2021
	Loan Balance		Specific Allocations		Loan Balance		Specific Allocations
Commercial and industrial	$	21,529	$	6,475	$	24,523	$	10,536
Energy	11,931		5,191		16,393		5,480
Paycheck Protection Program	—		—		—		—
Commercial real estate:
Buildings, land and other	28,806		326		24,670		200
Construction	—		—		948		200
Consumer real estate	302		36		303		36
Consumer and other	—		—		—		—
Total	$	62,568	$	12,028	$	66,837	$	16,452

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Goodwill and Other Intangible Assets

3 Months Ended

Mar. 31, 2022

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Other Intangible Assets

Goodwill and Other Intangible Assets

Goodwill and other intangible assets are presented in the table below.

	March 31, 2022		December 31, 2021
Goodwill	$	654,952	$	654,952
Other intangible assets:
Core deposits	$	591	$	718
Customer relationships	129		148
	$	720	$	866

The estimated aggregate future amortization expense for intangible assets remaining as of March 31, 2022 is as follows:

Remainder of 2022	$	335
2023	282
2024	87
2025	11
2026	5
Thereafter	—
	$	720

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Deposits

3 Months Ended

Mar. 31, 2022

Disclosure Text Block [Abstract]

Deposits

Deposits

Deposits were as follows:

	March 31, 2022		December 31, 2021
Non-interest-bearing demand deposits	$	18,114,430	$	18,423,018
Interest-bearing deposits:
Savings and interest checking	12,484,308		11,930,959
Money market accounts	12,490,612		11,228,815
Time accounts	1,341,579		1,112,904
Total interest-bearing deposits	26,316,499		24,272,678
Total deposits	$	44,430,929	$	42,695,696

The following table presents additional information about our deposits:

	March 31, 2022		December 31, 2021
Deposits from foreign sources (primarily Mexico)	$	1,092,302	$	993,479
Non-interest-bearing public funds deposits	746,097		1,235,026
Interest-bearing public funds deposits	975,511		810,863
Total deposits not covered by deposit insurance	25,213,248		24,125,359
Time deposits not covered by deposit insurance	357,529		238,608

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Commitments and Contingencies

3 Months Ended

Mar. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments Contingencies and Guarantees

Off-Balance-Sheet Arrangements, Commitments, Guarantees and Contingencies

Financial Instruments with Off-Balance-Sheet Risk. In the normal course of business, we enter into various transactions, which, in accordance with generally accepted accounting principles are not included in our consolidated balance sheets. We enter into these transactions to meet the financing needs of our customers. As more fully discussed in our 2021 Form 10-K, these transactions include commitments to extend credit and standby letters of credit, which involve, to varying degrees, elements of credit risk and interest rate risk in excess of the amounts recognized in the consolidated balance sheets. We minimize our exposure to loss under these commitments by subjecting them to credit approval and monitoring procedures.

Financial instruments with off-balance-sheet risk were as follows:

	March 31, 2022		December 31, 2021
Commitments to extend credit	$	10,356,196	$	10,420,142
Standby letters of credit	236,798		238,690
Deferred standby letter of credit fees	1,704		2,072

Allowance For Credit Losses - Off-Balance-Sheet Credit Exposures. The allowance for credit losses on off-balance-sheet credit exposures is a liability account, calculated in accordance with ASC 326, representing expected credit losses over the contractual period for which we are exposed to credit risk resulting from a contractual obligation to extend credit. No allowance is recognized if we have the unconditional right to cancel the obligation. Off-balance-sheet credit exposures primarily consist of amounts available under outstanding lines of credit and letters of credit detailed in the table above. The amount of the allowance represents management's best estimate of expected credit losses on commitments expected to be funded over the contractual life of the commitment. Our allowance methodology is more fully described in our 2021 Form 10-K.

The following table details activity in the allowance for credit losses on off-balance-sheet credit exposures.

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	50,314	$	44,152
Credit loss expense (benefit)	(4,464)		65
Ending balance	$	45,850	$	44,217

Lease Commitments. We lease certain office facilities and office equipment under operating leases. The components of total lease expense were as follows:

	Three Months Ended March 31,
	2022		2021
Amortization of lease right-of-use assets	$	8,105	$	8,283
Short-term lease expense	613		204
Non-lease components (including taxes, insurance, common maintenance, etc.)	3,020		3,004
Total	$	11,738	$	11,491

Right-of-use lease assets totaled $279.5 million at March 31, 2022 and $281.4 million at December 31, 2021 and are reported as a component of premises and equipment on our accompanying consolidated balance sheets. The related lease liabilities totaled $311.8 million at March 31, 2022 and $313.4 million at December 31, 2021 and are reported as a component of accrued interest payable and other liabilities in the accompanying consolidated balance sheets. Lease payments under operating leases that were applied to our operating lease liability totaled $8.0 million during the three months ended March 31, 2022 and $8.1 million during the three months ended March 31, 2021. There has been no significant change in our expected future minimum lease payments since December 31, 2021. See the 2021 Form 10-K for information regarding these commitments.

Litigation. We are subject to various claims and legal actions that have arisen in the course of conducting business. Management does not expect the ultimate disposition of these matters to have a material adverse impact on our financial statements.

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Capital and Regulatory Matters

3 Months Ended

Mar. 31, 2022

Banking Regulation, Common Equity Tier One Risk-Based Capital [Abstract]

Capital and Regulatory Matters

Capital and Regulatory Matters

Banks and bank holding companies are subject to various regulatory capital requirements administered by state and federal banking agencies. Capital adequacy guidelines and, additionally for banks, prompt corrective action regulations, involve quantitative measures of assets, liabilities, and certain off-balance-sheet items calculated under regulatory accounting practices. Capital amounts and classifications are also subject to qualitative judgments by regulators about components, risk weighting and other factors.

Cullen/Frost’s and Frost Bank’s Common Equity Tier 1 capital (“CET1”) includes common stock and related paid-in capital, net of treasury stock, and retained earnings. In connection with the adoption of the Basel III Capital Rules, we elected to opt-out of the requirement to include most components of accumulated other comprehensive income in CET1. We also elected to exclude the effects of credit loss accounting under CECL from CET1 for a five-year transitional period, as further discussed in our 2021 Form 10-K. This CECL transitional adjustment totaled $46.2 million and $61.6 million at March 31, 2022 and December 31, 2021, respectively. CET1 is reduced by goodwill and other intangible assets, net of associated deferred tax liabilities. Frost Bank's CET1 is also reduced by its equity investment in its financial subsidiary, Frost Insurance Agency (“FIA”).

Tier 1 capital includes CET1 and additional Tier 1 capital. For Cullen/Frost, additional Tier 1 capital included $145.5 million of 4.450% non-cumulative perpetual preferred stock at March 31, 2022 and December 31, 2021, the details of which are further discussed below. Frost Bank did not have any additional Tier 1 capital beyond Common Equity Tier 1 at March 31, 2022 or December 31, 2021. Total capital includes Tier 1 capital and Tier 2 capital. Tier 2 capital for both Cullen/Frost and Frost Bank includes a permissible portion of the allowances for credit losses on securities, loans and off-balance-sheet credit exposures. Tier 2 capital for Cullen/Frost also includes the permissible portion of qualified subordinated debt (which decreases 20.0% per year during the final five years of the term of the notes) totaling $80.0 million at March 31, 2022 and $100.0 million at December 31, 2021 and trust preferred securities totaling $120.0 million at both March 31, 2022 and December 31, 2021.

The following table presents actual and required capital ratios as of March 31, 2022 and December 31, 2021 for Cullen/Frost and Frost Bank under the Basel III Capital Rules. Capital levels required to be considered well capitalized are based upon prompt corrective action regulations, as amended to reflect the changes under the Basel III Capital Rules. See the 2021 Form 10-K for a more detailed discussion of the Basel III Capital Rules.

	Actual				Minimum Capital Required - Basel III				Required to be Considered Well Capitalized
	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
March 31, 2022
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,412,080	12.78	%	$	1,869,007	7.00	%	$	1,735,506	6.50	%
Frost Bank	3,301,515		12.39		1,865,304		7.00		1,732,068		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,557,532		13.32		2,269,508		8.50		2,136,007		8.00
Frost Bank	3,301,515		12.39		2,265,012		8.50		2,131,776		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,998,333		14.97		2,803,510		10.50		2,670,009		10.00
Frost Bank	3,542,316		13.29		2,797,956		10.50		2,664,720		10.00
Leverage Ratio
Cullen/Frost	3,557,532		7.08		2,010,897		4.00		2,513,621		5.00
Frost Bank	3,301,515		6.57		2,009,767		4.00		2,512,209		5.00
December 31, 2021
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,371,043	13.13	%	$	1,796,549	7.00	%	$	1,668,224	6.50	%
Frost Bank	3,261,532		12.72		1,795,221		7.00		1,666,991		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,516,495		13.70		2,181,523		8.50		2,053,198		8.00
Frost Bank	3,261,532		12.72		2,179,911		8.50		2,051,681		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,966,244		15.45		2,694,823		10.50		2,566,498		10.00
Frost Bank	3,491,281		13.61		2,692,831		10.50		2,564,601		10.00
Leverage Ratio
Cullen/Frost	3,516,495		7.34		1,917,533		4.00		2,396,917		5.00
Frost Bank	3,261,532		6.80		1,917,679		4.00		2,397,099		5.00

As of March 31, 2022, capital levels at Cullen/Frost and Frost Bank exceed all capital adequacy requirements under the Basel III Capital Rules. Based on the ratios presented above, capital levels as of March 31, 2022 at Cullen/Frost and Frost Bank exceed the minimum levels necessary to be considered “well capitalized.”

Cullen/Frost and Frost Bank are subject to the regulatory capital requirements administered by the Federal Reserve Board and, for Frost Bank, the Federal Deposit Insurance Corporation (“FDIC”). Regulatory authorities can initiate certain mandatory actions if Cullen/Frost or Frost Bank fail to meet the minimum capital requirements, which could have a direct material effect on our financial statements. Management believes, as of March 31, 2022, that Cullen/Frost and Frost Bank meet all capital adequacy requirements to which they are subject.

Preferred Stock. Outstanding preferred stock includes 150,000 shares, or $150.0 million in aggregate liquidation preference, of our 4.450% Non-Cumulative Perpetual Preferred Stock, Series B, par value $0.01 and liquidation preference $1,000 per share (“Series B Preferred Stock”). Each share of Series B Preferred Stock issued and outstanding is represented by 40 depositary shares, each representing a 1/40th ownership interest in a share of the Series B Preferred Stock (equivalent to a liquidation preference of $25 per share). The Series B Preferred Stock qualifies as Tier 1 capital for the purposes of the regulatory capital calculations. The net proceeds from the issuance and sale of the Series B Preferred Stock, after deducting $4.5 million of issuance costs including the underwriting discount and professional service fees, among other things, were approximately $145.5 million. Refer to our 2021 Form 10-K for additional details related to our Series B Preferred Stock.

Stock Repurchase Plans. From time to time, our board of directors has authorized stock repurchase plans. In general, stock repurchase plans allow us to proactively manage our capital position and return excess capital to shareholders. Shares purchased under such plans also provide us with shares of common stock necessary to satisfy obligations related to stock compensation awards. On January 26, 2022, our board of directors authorized a $100.0 million stock repurchase program, allowing us to repurchase shares of our common stock over a one-year period from time to time at various prices in the open market or through private transactions. No shares have been repurchased under this plan or the prior plan during the reported periods. Under the Basel III Capital Rules, Cullen/Frost may not repurchase or redeem any of its subordinated notes and, in some cases, its common stock without the prior approval of the Federal Reserve Board.

Dividend Restrictions. In the ordinary course of business, Cullen/Frost is dependent upon dividends from Frost Bank to provide funds for the payment of dividends to shareholders and to provide for other cash requirements, including to repurchase its common stock. Banking regulations may limit the amount of dividends that may be paid. Approval by regulatory authorities is required if the effect of dividends declared would cause the regulatory capital of Frost Bank to fall below specified minimum levels. Approval is also required if dividends declared exceed the net profits for that year combined with the retained net profits for the preceding two years. Under the foregoing dividend restrictions and while maintaining its “well capitalized” status, at March 31, 2022, Frost Bank could pay aggregate dividends of up to $325.0 million to Cullen/Frost without prior regulatory approval.

Under the terms of the junior subordinated deferrable interest debentures that Cullen/Frost has issued to Cullen/Frost Capital Trust II, Cullen/Frost has the right at any time during the term of the debentures to defer the payment of interest at any time or from time to time for an extension period not exceeding 20 consecutive quarterly periods with respect to each extension period. In the event that we have elected to defer interest on the debentures, we may not, with certain exceptions, declare or pay any dividends or distributions on our capital stock or purchase or acquire any of our capital stock.

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Derivative Financial Instruments

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Financial Instruments

Derivative Financial Instruments

The fair value of derivative positions outstanding is included in accrued interest receivable and other assets and accrued interest payable and other liabilities in the accompanying consolidated balance sheets and in the net change in each of these financial statement line items in the accompanying consolidated statements of cash flows.

Interest Rate Derivatives. We utilize interest rate swaps, caps, swaptions and floors to mitigate exposure to interest rate risk and to facilitate the needs of our customers. Our objectives for utilizing these derivative instruments are described in our 2021 Form 10-K.

The notional amounts and estimated fair values of interest rate derivative contracts are presented in the following table. The fair values of interest rate derivative contracts are estimated utilizing internal valuation methods with observable market data inputs, or as determined by the Chicago Mercantile Exchange (“CME”) for centrally cleared derivative contracts. CME rules legally characterize variation margin payments for centrally cleared derivatives as settlements of the derivatives' exposure rather than collateral. As a result, the variation margin payment and the related derivative instruments are considered a single unit of account for accounting and financial reporting purposes. Variation margin, as determined by the CME, is settled daily. As a result, derivative contracts that clear through the CME have an estimated fair value of zero as of March 31, 2022 and December 31, 2021.

	March 31, 2022				December 31, 2021
	Notional Amount		Estimated Fair Value		Notional Amount		Estimated Fair Value
Derivatives designated as hedges of fair value:
Financial institution counterparties:
Loan/lease interest rate swaps – assets	$	1,807	$	1	$	—	$	—
Loan/lease interest rate swaps – liabilities	280		(3)		2,426		(34)
Non-hedging interest rate derivatives:
Financial institution counterparties:
Loan/lease interest rate swaps – assets	697,834		15,311		247,592		1,207
Loan/lease interest rate swaps – liabilities	447,742		(6,184)		928,756		(19,142)
Loan/lease interest rate caps – assets	265,930		8,110		270,431		3,239
Customer counterparties:
Loan/lease interest rate swaps – assets	447,742		10,275		928,756		39,864
Loan/lease interest rate swaps – liabilities	697,834		(25,437)		247,592		(2,846)
Loan/lease interest rate caps – liabilities	265,930		(8,110)		270,431		(3,239)

The weighted-average rates paid and received for interest rate swaps outstanding at March 31, 2022 were as follows:

	Weighted-Average
	Interest Rate Paid		Interest Rate Received
Interest rate swaps:
Fair value hedge loan/lease interest rate swaps	2.11	%	0.26	%
Non-hedging interest rate swaps – financial institution counterparties	3.69		2.07
Non-hedging interest rate swaps – customer counterparties	2.07		3.69

The weighted-average strike rate for outstanding interest rate caps was 3.27% at March 31, 2022.

Commodity Derivatives. We enter into commodity swaps and option contracts that are not designated as hedging instruments primarily to accommodate the business needs of our customers. Upon the origination of a commodity swap or option contract with a customer, we simultaneously enter into an offsetting contract with a third party financial institution to mitigate the exposure to fluctuations in commodity prices.

The notional amounts and estimated fair values of non-hedging commodity swap and option derivative positions outstanding are presented in the following table. We obtain dealer quotations and use internal valuation methods with observable market data inputs to value our commodity derivative positions.

		March 31, 2022			December 31, 2021
	Notional Units	Notional Amount	Estimated Fair Value		Notional Amount	Estimated Fair Value
Financial institution counterparties:
Oil – assets	Barrels	2,988	$	9,735	4,809	$	14,721
Oil – liabilities	Barrels	9,767	(189,416)		7,032	(73,594)
Natural gas – assets	MMBTUs	14,564	1,813		15,947	4,143
Natural gas – liabilities	MMBTUs	27,474	(50,244)		29,446	(21,249)
Customer counterparties:
Oil – assets	Barrels	9,767	190,776		7,046	74,437
Oil – liabilities	Barrels	2,988	(9,710)		4,796	(14,294)
Natural gas – assets	MMBTUs	27,474	50,423		29,446	21,456
Natural gas – liabilities	MMBTUs	14,564	(1,811)		15,947	(4,124)

Foreign Currency Derivatives. We enter into foreign currency forward contracts that are not designated as hedging instruments primarily to accommodate the business needs of our customers. Upon the origination of a foreign currency denominated transaction with a customer, we simultaneously enter into an offsetting contract with a third party financial institution to negate the exposure to fluctuations in foreign currency exchange rates. We also utilize foreign currency forward contracts that are not designated as hedging instruments to mitigate the economic effect of fluctuations in foreign currency

exchange rates on foreign currency holdings and certain short-term, non-U.S. dollar denominated loans. The notional amounts and fair values of open foreign currency forward contracts were as follows:

		March 31, 2022			December 31, 2021
	Notional Currency	Notional Amount	Estimated Fair Value		Notional Amount	Estimated Fair Value
Financial institution counterparties:
Forward contracts – assets	EUR	2,400	$	18	1,900	$	29
Forward contracts – assets	CAD	—	—		658	—
Forward contracts – liabilities	EUR	6,500	(111)		—	—
Forward contracts – liabilities	CAD	658	(6)		—	—
Customer counterparties:
Forward contracts – assets	EUR	6,500	122		—	—
Forward contracts – assets	CAD	658	10		658	4
Forward contracts – liabilities	EUR	2,400	(14)		1,900	(55)

Gains, Losses and Derivative Cash Flows. For fair value hedges, the changes in the fair value of both the derivative hedging instrument and the hedged item are included in other non-interest income or other non-interest expense. The extent that such changes in fair value do not offset represents hedge ineffectiveness. Net cash flows from interest rate swaps on commercial loans/leases designated as hedging instruments in effective hedges of fair value are included in interest income on loans. For non-hedging derivative instruments, gains and losses due to changes in fair value and all cash flows are included in other non-interest income and other non-interest expense.

Amounts included in the consolidated statements of income related to interest rate derivatives designated as hedges of fair value were as follows:

	Three Months Ended March 31,
	2022		2021
Commercial loan/lease interest rate swaps:
Amount of gain (loss) included in interest income on loans	$	(13)	$	(28)
Amount of (gain) loss included in other non-interest expense	2		(3)

As stated above, we enter into non-hedge related derivative positions primarily to accommodate the business needs of our customers. Upon the origination of a derivative contract with a customer, we simultaneously enter into an offsetting derivative contract with a third party financial institution. We recognize immediate income based upon the difference in the bid/ask spread of the underlying transactions with our customers and the third party. Because we act only as an intermediary for our customer, subsequent changes in the fair value of the underlying derivative contracts for the most part offset each other and do not significantly impact our results of operations.

Amounts included in the consolidated statements of income related to non-hedge related derivative instruments are presented in the table below.

	Three Months Ended March 31,
	2022		2021
Non-hedging interest rate derivatives:
Other non-interest income	$	516	$	1,587
Other non-interest expense	—		(1)
Non-hedging commodity derivatives:
Other non-interest income	929		1,154
Non-hedging foreign currency derivatives:
Other non-interest income	18		30

Counterparty Credit Risk. Our credit exposure relating to interest rate swaps, commodity swaps/options and foreign currency forward contracts with bank customers was approximately $238.4 million at March 31, 2022. This credit exposure is partly mitigated as transactions with customers are generally secured by the collateral, if any, securing the underlying transaction being hedged. Our credit exposure, net of collateral pledged, relating to interest rate swaps, commodity swaps/options and foreign currency forward contracts with upstream financial institution counterparties was approximately $35.7 million at March 31, 2022. This amount was primarily related to initial margin payments to the CME and excess collateral we

posted to counterparties. Collateral levels for upstream financial institution counterparties are monitored and adjusted as necessary. See Note 9 – Balance Sheet Offsetting and Repurchase Agreements for additional information regarding our credit exposure with upstream financial institution counterparties. At March 31, 2022, we had $247.3 million in cash collateral related to derivative contracts on deposit with other financial institution counterparties.

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Balance Sheet Offsetting

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Balance Sheet Offsetting

Balance Sheet Offsetting and Repurchase Agreements

Balance Sheet Offsetting. Certain financial instruments, including resell and repurchase agreements and derivatives, may be eligible for offset in the consolidated balance sheet and/or subject to master netting arrangements or similar agreements. Our derivative transactions with upstream financial institution counterparties are generally executed under International Swaps and Derivative Association (“ISDA”) master agreements which include “right of set-off” provisions. In such cases there is generally a legally enforceable right to offset recognized amounts and there may be an intention to settle such amounts on a net basis. Nonetheless, we do not generally offset such financial instruments for financial reporting purposes.

Information about financial instruments that are eligible for offset in the consolidated balance sheet as of March 31, 2022 is presented in the following tables.

	Gross Amount Recognized		Gross Amount Offset		Net Amount Recognized
March 31, 2022
Financial assets:
Derivatives:
Loan/lease interest rate swaps and caps	$	23,422	$	—	$	23,422
Commodity swaps and options	11,548		—		11,548
Foreign currency forward contracts	18		—		18
Total derivatives	34,988		—		34,988
Resell agreements	—		—		—
Total	$	34,988	$	—	$	34,988
Financial liabilities:
Derivatives:
Loan/lease interest rate swaps and caps	$	6,187	$	—	$	6,187
Commodity swaps and options	239,660		—		239,660
Foreign currency forward contracts	117		—		117
Total derivatives	245,964		—		245,964
Repurchase agreements	1,842,618		—		1,842,618
Total	$	2,088,582	$	—	$	2,088,582

			Gross Amounts Not Offset
	Net Amount Recognized		Financial Instruments		Collateral		Net Amount
March 31, 2022
Financial assets:
Derivatives:
Counterparty A	$	32	$	(32)	$	—	$	—
Counterparty B	11,998		(11,998)		—		—
Other counterparties	22,958		(16,251)		(6,707)		—
Total derivatives	34,988		(28,281)		(6,707)		—
Resell agreements	—		—		—		—
Total	$	34,988	$	(28,281)	$	(6,707)	$	—
Financial liabilities:
Derivatives:
Counterparty A	$	2,635	$	(32)	$	(2,603)	$	—
Counterparty B	46,953		(11,998)		(34,955)		—
Counterparty C	3		—		(3)		—
Other counterparties	196,373		(16,251)		(180,122)		—
Total derivatives	245,964		(28,281)		(217,683)		—
Repurchase agreements	1,842,618		—		(1,842,618)		—
Total	$	2,088,582	$	(28,281)	$	(2,060,301)	$	—

Information about financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2021 is presented in the following tables.

	Gross Amount Recognized		Gross Amount Offset		Net Amount Recognized
December 31, 2021
Financial assets:
Derivatives:
Loan/lease interest rate swaps and caps	$	4,446	$	—	$	4,446
Commodity swaps and options	18,864		—		18,864
Total derivatives	23,339		—		23,339
Resell agreements	7,903		—		7,903
Total	$	31,242	$	—	$	31,242
Financial liabilities:
Derivatives:
Loan/lease interest rate swaps and caps	$	19,176	$	—	$	19,176
Commodity swaps and options	94,843		—		94,843
Total derivatives	114,019		—		114,019
Repurchase agreements	2,740,799		—		2,740,799
Total	$	2,854,818	$	—	$	2,854,818

			Gross Amounts Not Offset
	Net Amount Recognized		Financial Instruments		Collateral		Net Amount
December 31, 2021
Financial assets:
Derivatives:
Counterparty A	$	6	$	(6)	$	—	$	—
Counterparty B	7,655		(7,655)		—		—
Other counterparties	15,678		(15,678)		—		—
Total derivatives	23,339		(23,339)		—		—
Resell agreements	7,903		—		(7,903)		—
Total	$	31,242	$	(23,339)	$	(7,903)	$	—
Financial liabilities:
Derivatives:
Counterparty A	$	3,870	$	(6)	$	(3,864)	$	—
Counterparty B	28,130		(7,655)		(20,475)		—
Counterparty C	9		—		(9)		—
Other counterparties	82,010		(15,678)		(66,225)		107
Total derivatives	114,019		(23,339)		(90,573)		107
Repurchase agreements	2,740,799		—		(2,740,799)		—
Total	$	2,854,818	$	(23,339)	$	(2,831,372)	$	107

Repurchase Agreements. We utilize securities sold under agreements to repurchase to facilitate the needs of our customers and to facilitate secured short-term funding needs. Securities sold under agreements to repurchase are stated at the amount of cash received in connection with the transaction. We monitor collateral levels on a continuous basis. We may be required to provide additional collateral based on the fair value of the underlying securities. Securities pledged as collateral under repurchase agreements are maintained with our safekeeping agents.

The remaining contractual maturity of repurchase agreements in the consolidated balance sheets as of March 31, 2022 and December 31, 2021 is presented in the following tables.

	Remaining Contractual Maturity of the Agreements
	Overnight and Continuous		Up to 30 Days		30-90 Days		Greater than 90 Days		Total
March 31, 2022
Repurchase agreements:
U.S. Treasury	$	876,879	$	—	$	—	$	—	$	876,879
Residential mortgage-backed securities	965,739		—		—		—		965,739
Total borrowings	$	1,842,618	$	—	$	—	$	—	$	1,842,618
Gross amount of recognized liabilities for repurchase agreements									$	1,842,618
Amounts related to agreements not included in offsetting disclosures above									$	—
December 31, 2021
Repurchase agreements:
U.S. Treasury	$	1,342,591	$	—	$	—	$	—	$	1,342,591
Residential mortgage-backed securities	1,398,208		—		—		—		1,398,208
Total borrowings	$	2,740,799	$	—	$	—	$	—	$	2,740,799
Gross amount of recognized liabilities for repurchase agreements									$	2,740,799
Amounts related to agreements not included in offsetting disclosures above									$	—

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Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation

Stock-Based Compensation

A combined summary of activity in our active stock plans is presented in the table below. Performance stock units outstanding are presented assuming attainment of the maximum payout rate as set forth by the performance criteria. As of March 31, 2022, there were 794,493 shares remaining available for grant for future stock-based compensation awards.

	Deferred Stock Units Outstanding			Non-Vested Stock Units Outstanding			Performance Stock Units Outstanding			Stock Options Outstanding
	Number of Units	Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant		Number of Shares	Weighted- Average Exercise Price
Balance, January 1, 2022	56,301	$	79.21	449,337	$	93.05	202,460	$	84.71	877,681	$	69.02
Authorized	—	—		—	—		—	—		—	—
Granted	—	—		1,038	145.32		—	—		—	—
Exercised/vested	—	—		—	—		(25,180)	87.18		(90,250)	63.59
Forfeited/expired	—	—		(1,786)	89.50		(16,058)	87.18		—	—
Balance, March 31, 2022	56,301	79.21		448,589	93.19		161,222	84.08		787,431	69.64

Shares issued in connection with stock compensation awards are issued from available treasury shares. If no treasury shares are available, new shares are issued from available authorized shares. Shares issued in connection with stock compensation awards along with other related information were as follows:

	Three Months Ended March 31,
	2022		2021
New shares issued from available authorized shares	—		—
Shares issued from available treasury stock	115,430		513,824
Proceeds from stock option exercises	$	5,739	$	29,397

Stock-based compensation expense is recognized ratably over the requisite service period for all awards. For most stock option awards, the service period generally matches the vesting period. For stock options granted to certain executive officers and for non-vested stock units granted to all participants, the service period does not extend past the date the participant reaches 65 years of age. Deferred stock units granted to non-employee directors generally have immediate vesting and the related expense is fully recognized on the date of grant. For performance stock units, the service period generally matches the three-year performance period specified by the award, however, the service period does not extend past the date the participant reaches 65 years of age. Expense recognized each period is dependent upon our estimate of the number of shares that will ultimately be issued.

Stock-based compensation expense or benefit and the related income tax benefit is presented in the following table. The service period for performance stock units granted each year begins on January 1 of the following year.

	Three Months Ended March 31,
	2022		2021
Non-vested stock units	$	2,358	$	1,883
Performance stock units	(246)		643
Total	$	2,112	$	2,526
Income tax benefit	$	708	$	367

Unrecognized stock-based compensation expense at March 31, 2022 is presented in the table below. Unrecognized stock-based compensation expense related to performance stock units is presented assuming attainment of the maximum payout rate as set forth by the performance criteria.

Non-vested stock units	$	16,063
Performance stock units	8,664
Total	$	24,727

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Earnings Per Common Share

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Earnings Per Common Share

Earnings Per Common Share

Earnings per common share is computed using the two-class method as more fully described in our 2021 Form 10-K. The following table presents a reconciliation of net income available to common shareholders, net earnings allocated to common stock and the number of shares used in the calculation of basic and diluted earnings per common share.

	Three Months Ended March 31,
	2022		2021
Net income	$	99,102	$	116,015
Less: Preferred stock dividends	1,669		2,151
Net income available to common shareholders	97,433		113,864
Less: Earnings allocated to participating securities	849		1,162
Net earnings allocated to common stock	$	96,584	$	112,702
Distributed earnings allocated to common stock	$	48,051	$	45,660
Undistributed earnings allocated to common stock	48,533		67,042
Net earnings allocated to common stock	$	96,584	$	112,702
Weighted-average shares outstanding for basic earnings per common share	64,051,202		63,306,493
Dilutive effect of stock compensation	409,705		509,290
Weighted-average shares outstanding for diluted earnings per common share	64,460,907		63,815,783

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Defined Benefit Plans

3 Months Ended

Mar. 31, 2022

Retirement Benefits [Abstract]

Defined Benefit Plans

Defined Benefit Plans

The components of the combined net periodic expense (benefit) for our defined benefit pension plans are presented in the table below.

	Three Months Ended March 31,
	2022		2021
Expected return on plan assets, net of expenses	$	(3,491)	$	(3,210)
Interest cost on projected benefit obligation	1,004		835
Net amortization and deferral	741		1,529
Net periodic expense (benefit)	$	(1,746)	$	(846)

Our non-qualified defined benefit pension plan is not funded. No contributions to the qualified defined benefit pension plan were made during the three months ended March 31, 2022. We do not expect to make any contributions to the qualified defined benefit plan during the remainder of 2022.

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Income Taxes

3 Months Ended

Mar. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

Income tax expense was as follows:

	Three Months Ended March 31,
	2022			2021
Current income tax expense (benefit)	$	13,059		$	3,725
Deferred income tax expense (benefit)	(432)			4,172
Income tax expense, as reported	$	12,627		$	7,897
Effective tax rate	11.3		%	6.4		%

We had a net deferred tax asset totaling $110.3 million at March 31, 2022 and a net deferred tax liability totaling $81.2 million at December 31, 2021. No valuation allowance for deferred tax assets was recorded at March 31, 2022 as management believes it is more likely than not that all of the deferred tax assets will be realized against deferred tax liabilities and projected future taxable income.

The effective income tax rates differed from the U.S. statutory federal income tax rates of 21% during the comparable periods primarily due to the effect of tax-exempt income from loans, securities and life insurance policies and the income tax effects associated with stock-based compensation. There were no unrecognized tax benefits during any of the reported periods.

Interest and/or penalties related to income taxes are reported as a component of income tax expense. Such amounts were not significant during the reported periods.

We file income tax returns in the U.S. federal jurisdiction. We are no longer subject to U.S. federal income tax examinations by tax authorities for years before 2018.

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Other Comprehensive Income (Loss)

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Comprehensive Income (Loss) Note

Other Comprehensive Income (Loss)

The before and after tax amounts allocated to each component of other comprehensive income (loss) are presented in the following table. Reclassification adjustments related to securities available for sale are included in net gain (loss) on securities transactions in the accompanying consolidated statements of income. Reclassification adjustments related to defined-benefit post-retirement benefit plans are included in the computation of net periodic pension expense (see Note 12 – Defined Benefit Plans).

	Three Months Ended March 31, 2022						Three Months Ended March 31, 2021
	Before Tax Amount		Tax  Expense, (Benefit)		Net of  Tax Amount		Before Tax Amount		Tax  Expense, (Benefit)		Net of  Tax Amount
Securities available for sale and transferred securities:
Change in net unrealized gain/loss during the period	$	(910,795)	$	(191,267)	$	(719,528)	$	(159,779)	$	(33,554)	$	(126,225)
Change in net unrealized gain on securities transferred to held to maturity	(209)		(44)		(165)		(259)		(54)		(205)
Reclassification adjustment for net (gains) losses included in net income	—		—		—		—		—		—
Total securities available for sale and transferred securities	(911,004)		(191,311)		(719,693)		(160,038)		(33,608)		(126,430)
Defined-benefit post-retirement benefit plans:
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic expense (benefit)	741		156		585		1,529		321		1,208
Total defined-benefit post-retirement benefit plans	741		156		585		1,529		321		1,208
Total other comprehensive income (loss)	$	(910,263)	$	(191,155)	$	(719,108)	$	(158,509)	$	(33,287)	$	(125,222)

Activity in accumulated other comprehensive income (loss), net of tax, was as follows:

	Securities Available For Sale		Defined Benefit Plans		Accumulated Other Comprehensive Income
Balance January 1, 2022	$	380,209	$	(32,891)	$	347,318
Other comprehensive income (loss) before reclassifications	(719,693)		—		(719,693)
Reclassification of amounts included in net income	—		585		585
Net other comprehensive income (loss) during period	(719,693)		585		(719,108)
Balance at March 31, 2022	$	(339,484)	$	(32,306)	$	(371,790)
Balance January 1, 2021	$	563,801	$	(50,831)	$	512,970
Other comprehensive income (loss) before reclassifications	(126,430)		—		(126,430)
Reclassification of amounts included in net income	—		1,208		1,208
Net other comprehensive income (loss) during period	(126,430)		1,208		(125,222)
Balance at March 31, 2021	$	437,371	$	(49,623)	$	387,748

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Operating Segments

3 Months Ended

Mar. 31, 2022

Segment Reporting [Abstract]

Operating Segments

Operating Segments

We are managed under a matrix organizational structure whereby our two primary operating segments, Banking and Frost Wealth Advisors, overlap a regional reporting structure. See our 2021 Form 10-K for additional information regarding our operating segments. Summarized operating results by segment were as follows:

	Banking		Frost  Wealth Advisors		Non-Banks		Consolidated
Three months ended:
March 31, 2022
Net interest income (expense)	$	250,119	$	700	$	(1,748)	$	249,071
Credit loss expense (benefit)	(1)		1		—		—
Non-interest income	58,706		43,229		(545)		101,390
Non-interest expense	206,538		30,910		1,284		238,732
Income (loss) before income taxes	102,288		13,018		(3,577)		111,729
Income tax expense (benefit)	11,014		2,734		(1,121)		12,627
Net income (loss)	91,274		10,284		(2,456)		99,102
Preferred stock dividends	—		—		1,669		1,669
Net income (loss) available to common shareholders	$	91,274	$	10,284	$	(4,125)	$	97,433
Revenues from (expenses to) external customers	$	308,825	$	43,929	$	(2,293)	$	350,461
March 31, 2021
Net interest income (expense)	$	242,205	$	486	$	(1,810)	$	240,881
Credit loss expense	63		—		—		63
Non-interest income	53,780		39,609		(153)		93,236
Non-interest expense	179,151		29,937		1,054		210,142
Income (loss) before income taxes	116,771		10,158		(3,017)		123,912
Income tax expense (benefit)	7,177		2,133		(1,413)		7,897
Net income (loss)	109,594		8,025		(1,604)		116,015
Preferred stock dividends	—		—		2,151		2,151
Net income (loss) available to common shareholders	$	109,594	$	8,025	$	(3,755)	$	113,864
Revenues from (expenses to) external customers	$	295,985	$	40,095	$	(1,963)	$	334,117

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Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair Value Measurements

The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. In estimating fair value, we utilize valuation techniques that are consistent with the market approach, the income approach and/or the cost approach. Such valuation techniques are consistently applied. Inputs to valuation techniques include the assumptions that market participants would use in pricing an asset or liability. ASC Topic 820 establishes a three-level fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. See our 2021 Form 10-K for additional information regarding the fair value hierarchy and a description of our valuation techniques.

Financial Assets and Financial Liabilities. The tables below summarize financial assets and financial liabilities measured at fair value on a recurring basis as of March 31, 2022 and December 31, 2021, segregated by the level of the valuation inputs within the fair value hierarchy of ASC Topic 820 utilized to measure fair value.

	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
March 31, 2022
Securities available for sale:
U.S. Treasury	$	3,507,746	$	—	$	—	$	3,507,746
Residential mortgage-backed securities	—		5,376,039		—		5,376,039
States and political subdivisions	—		7,258,393		—		7,258,393
Other	—		42,361		—		42,361
Trading account securities:
U.S. Treasury	23,939		—		—		23,939
States and political subdivisions	—		5,579		—		5,579
Derivative assets:
Interest rate swaps, caps and floors	—		33,697		—		33,697
Commodity swaps and options	—		252,747		—		252,747
Foreign currency forward contracts	150		—		—		150
Derivative liabilities:
Interest rate swaps, caps and floors	—		39,734		—		39,734
Commodity swaps and options	—		251,181		—		251,181
Foreign currency forward contracts	131		—		—		131
December 31, 2021
Securities available for sale:
U.S. Treasury	$	2,179,433	$	—	$	—	$	2,179,433
Residential mortgage-backed securities	—		4,066,265		—		4,066,265
States and political subdivisions	—		7,636,571		—		7,636,571
Other	—		42,359		—		42,359
Trading account securities:
U.S. Treasury	24,237		—		—		24,237
States and political subdivisions	—		925		—		925
Derivative assets:
Interest rate swaps, caps and floors	—		44,310		—		44,310
Commodity swaps and options	—		114,757		—		114,757
Foreign currency forward contracts	33		—		—		33
Derivative liabilities:
Interest rate swaps, caps and floors	—		25,261		—		25,261
Commodity swaps and options	—		113,261		—		113,261
Foreign currency forward contracts	55		—		—		55

Certain financial assets and financial liabilities are measured at fair value on a nonrecurring basis; that is, the instruments are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances. Financial assets measured at fair value on a non-recurring basis during the reported periods include certain collateral dependent loans reported at the fair value of the underlying collateral if repayment is expected solely from the collateral.

The following table presents collateral dependent loans that were remeasured and reported at fair value through a specific allocation of the allowance for credit losses on loans based upon the fair value of the underlying collateral during the reported periods.

	Three Months Ended March 31, 2022				Three Months Ended March 31, 2021
	Level 2		Level 3		Level 2		Level 3
Carrying value before allocations	$	2,064	$	5,711	$	100	$	15,013
Specific (allocations) reversals of prior allocations	(126)		3,965		—		600
Fair value	$	1,938	$	9,676	$	100	$	15,613

Non-Financial Assets and Non-Financial Liabilities. We do not have any non-financial assets or non-financial liabilities measured at fair value on a recurring basis. From time to time, non-financial assets measured at fair value on a non-recurring basis may include certain foreclosed assets which, upon initial recognition, were remeasured and reported at fair value through a charge-off to the allowance for loan losses and certain foreclosed assets which, subsequent to their initial recognition, were remeasured at fair value through a write-down included in other non-interest expense. There were no such fair value measurements during the reported periods.

Financial Instruments Reported at Amortized Cost. The estimated fair values of financial instruments that are reported at amortized cost in our consolidated balance sheets, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, were as follows:

	March 31, 2022				December 31, 2021
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Financial assets:
Level 2 inputs:
Cash and cash equivalents	$	14,457,083	$	14,457,083	$	16,583,000	$	16,583,000
Securities held to maturity	1,665,465		1,639,993		1,749,179		1,809,143
Cash surrender value of life insurance policies	189,471		189,471		190,139		190,139
Accrued interest receivable	131,370		131,370		179,111		179,111
Level 3 inputs:
Loans, net	16,295,702		16,053,955		16,087,731		16,079,454
Financial liabilities:
Level 2 inputs:
Deposits	44,430,929		44,422,700		42,695,696		41,343,426
Federal funds purchased	35,200		35,200		25,925		25,925
Repurchase agreements	1,842,618		1,842,618		2,740,799		2,740,799
Junior subordinated deferrable interest debentures	123,026		123,712		123,011		123,712
Subordinated notes	99,217		105,740		99,178		111,430
Accrued interest payable	2,147		2,147		3,026		3,026

Under ASC Topic 825, entities may choose to measure eligible financial instruments at fair value at specified election dates. The fair value measurement option (i) may be applied instrument by instrument, with certain exceptions, (ii) is generally irrevocable and (iii) is applied only to entire instruments and not to portions of instruments. Unrealized gains and losses on items for which the fair value measurement option has been elected must be reported in earnings at each subsequent reporting date. During the reported periods, we had no financial instruments measured at fair value under the fair value measurement option.

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Accounting Standards Updates

3 Months Ended

Mar. 31, 2022

Accounting Changes and Error Corrections [Abstract]

Accounting Standards Updates

Accounting Standards Updates

Information about certain recently issued accounting standards updates is presented below. Also refer to Note 20 - Accounting Standards Updates in our 2021 Form 10-K for additional information related to previously issued accounting standards updates.

ASU 2022-01, “Derivatives and Hedging (Topic 815): Fair Value Hedging - Portfolio Layer Method.” Under prior guidance, entities can apply the last-of-layer hedging method to hedge the exposure of a closed portfolio of prepayable financial assets to fair value changes due to changes in interest rates for a portion of the portfolio that is not expected to be affected by prepayments, defaults, and other events affecting the timing and amount of cash flows. ASU 2022-01 expands the last-of-layer method, which permits only one hedge layer, to allow multiple hedged layers of a single closed portfolio. To reflect that expansion, the last-of-layer method is renamed the portfolio layer method. ASU 2022-01 also (i) expands the scope of the portfolio layer method to include non-prepayable financial assets, (ii) specifies eligible hedging instruments in a single-layer hedge, (iii) provides additional guidance on the accounting for and disclosure of hedge basis adjustments under the portfolio layer method and (iv) specifies how hedge basis adjustments should be considered when determining credit losses for the assets included in the closed portfolio. ASU 2022-01 will be effective for us on January 1, 2023 though early adoption is permitted. The adoption of ASU 2022-01 is not expected to have a significant impact on our financial statements.

ASU 2022-02, “Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures.” ASU 2022-02 eliminates the accounting guidance for troubled debt restructurings in Accounting Standards Codification (“ASC”) Subtopic 310-40, Receivables - Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Additionally, ASU 2022-02 requires entities to disclose current-period gross write-offs by year of origination for financing receivables and net investments in leases within the scope of ASC Subtopic 3126-20, Financial Instruments - Credit Losses - Measured at Amortized Cost. ASU 2022-02 will be effective for us on January 1, 2023 though early adoption is permitted. The adoption of ASU 2022-02 is not expected to have a significant impact on our financial statements.

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Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Nature of Operations

Nature of Operations. Cullen/Frost Bankers, Inc. (“Cullen/Frost”) is a financial holding company and a bank holding company headquartered in San Antonio, Texas that provides, through its subsidiaries, a broad array of products and services throughout numerous Texas markets. The terms “Cullen/Frost,” “the Corporation,” “we,” “us” and “our” mean Cullen/Frost Bankers, Inc. and its subsidiaries, when appropriate. In addition to general commercial and consumer banking, other products and services offered include trust and investment management, insurance, brokerage, mutual funds, leasing, treasury management, capital markets advisory and item processing.

Basis of Presentation

Basis of Presentation. The consolidated financial statements in this Quarterly Report on Form 10-Q include the accounts of Cullen/Frost and all other entities in which Cullen/Frost has a controlling financial interest. All significant intercompany balances and transactions have been eliminated in consolidation. The accounting and financial reporting policies we follow conform, in all material respects, to accounting principles generally accepted in the United States and to general practices within the financial services industry.

The consolidated financial statements in this Quarterly Report on Form 10-Q have not been audited by an independent registered public accounting firm, but in the opinion of management, reflect all adjustments necessary for a fair presentation of our financial position and results of operations. All such adjustments were of a normal and recurring nature. The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q adopted by the Securities and Exchange Commission (“SEC”). Accordingly, the financial statements do not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements and should be read in conjunction with our consolidated financial statements, and notes thereto, for the year ended December 31, 2021, included in our Annual Report on Form 10-K filed with the SEC on February 4, 2022 (the “2021 Form 10-K”). Operating results for the interim periods disclosed herein are not necessarily indicative of the results that may be expected for a full year or any future period.

Use of Estimates

Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. The allowance for loan losses and the fair values of financial instruments and the status of contingencies are particularly subject to change.

Reclassification, Policy [Policy Text Block]

Certain items in prior financial statements have been reclassified to conform to the current presentation.

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Loans Loans - Allowance For Credit Losses (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block]	Allowance For Credit Losses - Loans. The allowance for credit losses on loans is a contra-asset valuation account, calculated in accordance with ASC 326, that is deducted from the amortized cost basis of loans to present the net amount expected to be collected. The amount of the allowance represents management's best estimate of current expected credit losses on loans considering available information, from internal and external sources, relevant to assessing collectibility over the loans' contractual terms, adjusted for expected prepayments when appropriate. Credit loss expense related to loans reflects the totality of actions taken on all loans for a particular period including any necessary increases or decreases in the allowance related to changes in credit loss expectations associated with specific loans or pools of loans. Portions of the allowance may be allocated for specific credits; however, the entire allowance is available for any credit that, in management’s judgment, should be charged off. While management utilizes its best judgment and information available, the ultimate appropriateness of the allowance is dependent upon a variety of factors beyond our control, including the performance of our loan portfolio, the economy, changes in interest rates and the view of the regulatory authorities toward loan classifications. Our allowance methodology is more fully described in our 2021 Form 10-K.

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Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Additional Cash Flow Information

Additional cash flow information was as follows:

	Three Months Ended March 31,
	2022		2021
Cash paid for interest	$	8,069	$	9,719
Cash paid for income taxes	—		—
Significant non-cash transactions:
Unsettled securities transactions	78,769		21,957
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities	4,013		1,326
Treasury stock issued to 401(k) stock purchase plan	—		1,749

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Securities (Tables)

3 Months Ended

Mar. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Debt Securities, Held-to-maturity [Table Text Block]

A summary of the amortized cost, fair value and allowance for credit losses related to securities held to maturity as of March 31, 2022 and December 31, 2021 is presented below.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Allowance for Credit Losses		Net Carrying Amount
March 31, 2022
Residential mortgage-backed securities	$	526,969	$	—	$	17,519	$	509,450	$	—	$	526,969
States and political subdivisions	1,137,154		3,622		11,717		1,129,059		(158)		1,136,996
Other	1,500		—		16		1,484		—		1,500
Total	$	1,665,623	$	3,622	$	29,252	$	1,639,993	$	(158)	$	1,665,465
December 31, 2021
Residential mortgage-backed securities	$	527,264	$	18,766	$	—	$	546,030	$	—	$	527,264
States and political subdivisions	1,220,573		41,141		101		1,261,613		(158)		1,220,415
Other	1,500		—		—		1,500		—		1,500
Total	$	1,749,337	$	59,907	$	101	$	1,809,143	$	(158)	$	1,749,179

Moody's and Standard & Poor's Bond Ratings [Table Text Block]

The following table summarizes Moody's and/or Standard & Poor's bond ratings for our portfolio of held-to-maturity securities issued by States and political subdivisions and other securities as of March 31, 2022 and December 31, 2021:

	States and Political Subdivisions
	Not Guaranteed or Pre-Refunded		Guaranteed by the Texas PSF		Pre-Refunded		Total		Other Securities
March 31, 2022
Aaa/AAA	$	91,034	$	467,039	$	471,183	$	1,029,256	$	—
Aa/AA	107,898		—		—		107,898		—
Not rated	—		—		—		—		1,500
Total	$	198,932	$	467,039	$	471,183	$	1,137,154	$	1,500
December 31, 2021
Aaa/AAA	$	92,379	$	460,648	$	563,251	$	1,116,278	$	—
Aa/AA	104,295		—		—		104,295		—
Not rated	—		—		—		—		1,500
Total	$	196,674	$	460,648	$	563,251	$	1,220,573	$	1,500

Debt Securities, Held-to-maturity, Allowance for Credit Loss [Table Text Block]

The following table details activity in the allowance for credit losses on held-to-maturity securities during the three months ended March 31, 2022 and 2021.

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	158	$	160
Credit loss expense (benefit)	—		(2)
Ending balance	$	158	$	158

Amortized Cost, Estimated Fair Value and Allowance for Credit Losses of Securities Available for Sale

A summary of the amortized cost, fair value and allowance for credit losses related to securities available for sale as of March 31, 2022 and December 31, 2021 is presented below.

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Allowance for Credit Losses		Estimated Fair Value
March 31, 2022
U.S. Treasury	$	3,658,506	$	1,883	$	152,643	$	—	$	3,507,746
Residential mortgage-backed securities	5,696,906		7,246		328,113		—		5,376,039
States and political subdivisions	7,218,821		135,206		95,634		—		7,258,393
Other	42,361		—		—		—		42,361
Total	$	16,616,594	$	144,335	$	576,390	$	—	$	16,184,539
December 31, 2021
U.S. Treasury	$	2,165,702	$	23,333	$	9,602	$	—	$	2,179,433
Residential mortgage-backed securities	4,059,692		31,662		25,089		—		4,066,265
States and political subdivisions	7,178,135		463,810		5,374		—		7,636,571
Other	42,359		—		—		—		42,359
Total	$	13,445,888	$	518,805	$	40,065	$	—	$	13,924,628

Securities, with Unrealized Losses Segregated by Length of Impairment

The table below summarizes, as of March 31, 2022, securities available for sale in an unrealized loss position for which an allowance for credit losses has not been recorded, aggregated by type of security and length of time in a continuous unrealized loss position.

	Less than 12 Months				More than 12 Months				Total
	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
U.S. Treasury	$	3,220,375	$	152,643	$	—	$	—	$	3,220,375	$	152,643
Residential mortgage-backed securities	4,583,657		286,421		402,940		41,692		4,986,597		328,113
States and political subdivisions	1,233,614		93,136		13,602		2,498		1,247,216		95,634
Total	$	9,037,646	$	532,200	$	416,542	$	44,190	$	9,454,188	$	576,390

Amortized Cost and Estimated Fair Value of Securities, Excluding Trading Securities, Presented by Contractual Maturity

The following table summarizes the maturity distribution schedule of securities held to maturity and securities available for sale as of March 31, 2022. Mortgage-backed securities are included in maturity categories based on their stated maturity date. Expected maturities may differ from contractual maturities because issuers may have the right to call or prepay obligations. Other securities classified as available for sale include stock in the Federal Reserve Bank and the Federal Home Loan Bank, which have no maturity date. These securities have been included in the total column only.

	Within 1 Year		1 - 5 Years		5 - 10 Years		After 10 Years		Total
Held To Maturity
Amortized Cost
Residential mortgage-backed securities	$	16	$	—	$	514,842	$	12,111	$	526,969
States and political subdivisions	429,852		118,516		56,735		532,051		1,137,154
Other	—		1,500		—		—		1,500
Total	$	429,868	$	120,016	$	571,577	$	544,162	$	1,665,623
Estimated Fair Value
Residential mortgage-backed securities	$	16	$	—	$	498,078	$	11,356	$	509,450
States and political subdivisions	431,961		119,698		56,973		520,427		1,129,059
Other	—		1,484		—		—		1,484
Total	$	431,977	$	121,182	$	555,051	$	531,783	$	1,639,993
Available For Sale
Amortized Cost
U. S. Treasury	$	—	$	2,033,995	$	1,432,731	$	191,780	$	3,658,506
Residential mortgage-backed securities	102		12,917		19,060		5,664,827		5,696,906
States and political subdivisions	194,416		1,563,829		888,489		4,572,087		7,218,821
Other	—		—		—		—		42,361
Total	$	194,518	$	3,610,741	$	2,340,280	$	10,428,694	$	16,616,594
Estimated Fair Value
U. S. Treasury	$	—	$	1,978,865	$	1,350,553	$	178,328	$	3,507,746
Residential mortgage-backed securities	103		13,212		19,327		5,343,397		5,376,039
States and political subdivisions	197,231		1,603,985		899,602		4,557,575		7,258,393
Other	—		—		—		—		42,361
Total	$	197,334	$	3,596,062	$	2,269,482	$	10,079,300	$	16,184,539

Investment Income

Premium amortization and discount accretion included in interest income on securities was as follows:

	Three Months Ended March 31,
	2022		2021
Premium amortization	$	(29,060)	$	(31,235)
Discount accretion	1,406		637
Net (premium amortization) discount accretion	$	(27,654)	$	(30,598)

Trading Account Securities, at Estimated Fair Value

Trading account securities, at estimated fair value, were as follows:

	March 31, 2022		December 31, 2021
U.S. Treasury	$	23,939	$	24,237
States and political subdivisions	5,579		925
Total	$	29,518	$	25,162

Net Gains and Losses on Trading Account Securities

Net gains and losses on trading account securities were as follows:

	Three Months Ended March 31,
	2022		2021
Net gain on sales transactions	$	340	$	109
Net mark-to-market gains (losses)	(168)		(69)
Net gain (loss) on trading account securities	$	172	$	40

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Loans (Tables)

3 Months Ended

Mar. 31, 2022

Receivables [Abstract]

Loans

Loans were as follows:

	March 31, 2022		December 31, 2021
Commercial and industrial	$	5,584,117	$	5,364,954
Energy:
Production	820,107		878,436
Service	113,708		105,901
Other	102,764		93,455
Total energy	1,036,579		1,077,792
Paycheck Protection Program	207,669		428,882
Commercial real estate:
Commercial mortgages	5,918,011		5,867,062
Construction	1,421,878		1,304,271
Land	458,510		405,277
Total commercial real estate	7,798,399		7,576,610
Consumer real estate:
Home equity loans	321,842		324,157
Home equity lines of credit	544,822		519,098
Other	566,961		567,535
Total consumer real estate	1,433,625		1,410,790
Total real estate	9,232,024		8,987,400
Consumer and other	482,148		477,369
Total loans	$	16,542,537	$	16,336,397

Non-Accrual Loans, Segregated by Class of Loans

Non-accrual loans, segregated by class of loans, were as follows:

	March 31, 2022				December 31, 2021
	Total Non-Accrual		Non-Accrual with No Credit Loss Allowance		Total Non-Accrual		Non-Accrual with No Credit Loss Allowance
Commercial and industrial	$	16,693	$	6,135	$	22,582	$	4,701
Energy	12,271		6,912		14,433		8,533
Paycheck Protection Program	—		—		—		—
Commercial real estate:
Buildings, land and other	19,003		17,005		15,297		13,817
Construction	583		583		948		—
Consumer real estate	416		114		440		138
Consumer and other	—		—		13		13
Total	$	48,966	$	30,749	$	53,713	$	27,202

Financing Receivable, Non-Accrual Loans, Segregated by Class of Loan and Year of Origination

The following table presents non-accrual loans as of March 31, 2022 by class and year of origination.

	2021		2020		2019		2018		2017		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Commercial and industrial	$	—	$	478	$	4,101	$	3,910	$	1,552	$	1,033	$	2,038	$	3,581	$	16,693
Energy	—		—		—		5,039		1,137		—		5,997		98		12,271
Paycheck Protection Program	—		—		—		—		—		—		—		—		—
Commercial real estate:
Buildings, land and other	—		8,407		296		1,199		394		2,932		—		5,775		19,003
Construction	—		—		583		—		—		—		—		—		583
Consumer real estate	—		—		—		—		—		390		—		26		416
Consumer and other	—		—		—		—		—		—		—		—		—
Total	$	—	$	8,885	$	4,980	$	10,148	$	3,083	$	4,355	$	8,035	$	9,480	$	48,966

Age Analysis of Past Due Loans, Segregated by Class of Loans

An age analysis of past due loans (including both accruing and non-accruing loans), segregated by class of loans, as of March 31, 2022 was as follows:

	Loans 30-89 Days Past Due		Loans 90 or More Days Past Due		Total Past Due Loans		Current Loans		Total Loans		Accruing Loans 90 or More Days Past Due
Commercial and industrial	$	13,016	$	8,042	$	21,058	$	5,563,059	$	5,584,117	$	4,166
Energy	—		6,382		6,382		1,030,197		1,036,579		287
Paycheck Protection Program	671		8,377		9,048		198,621		207,669		8,377
Commercial real estate:
Buildings, land and other	21,542		11,546		33,088		6,343,433		6,376,521		1,046
Construction	1,988		—		1,988		1,419,890		1,421,878		—
Consumer real estate	4,210		2,409		6,619		1,427,006		1,433,625		2,103
Consumer and other	6,393		593		6,986		475,162		482,148		593
Total	$	47,820	$	37,349	$	85,169	$	16,457,368	$	16,542,537	$	16,572

Restructured Loans Past Due in Excess of 90 Days on Financing Receivables

Information as of or for the three months ended March 31, 2022 and 2021 related to loans restructured during the last twelve months is set forth in the following table.

	March 31, 2022		March 31, 2021
Restructured loans past due in excess of 90 days at period-end:
Number of loans	2		2
Dollar amount of loans	$	572	$	1,392
Charge-offs of restructured loans:
Recognized on previously restructured loans	723		1,433

Weighted Average Risk Grades for All Commercial Loans by Class and Year of Origination

The following tables present weighted-average risk grades for all commercial loans, by class and year of origination/renewal as of March 31, 2022. Paycheck Protection Program (“PPP”) loans are excluded as such loans are fully guaranteed by the Small Business Administration (“SBA”).

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial and industrial
Risk grades 1-8	$	836,152	$	894,663	$	592,780	$	305,667	$	160,622	$	243,869	$	2,255,878	$	44,778	$	5,334,409	6.18
Risk grade 9	4,702		34,513		6,562		11,434		21,841		8,319		54,008		4,721		146,100		9.00
Risk grade 10	3,500		22,084		6,527		1,039		4,007		578		13,899		1,198		52,832		10.00
Risk grade 11	—		1,926		6,672		9,679		1,697		2,200		5,958		5,951		34,083		11.00
Risk grade 12	—		478		2,644		3,510		1,488		619		941		2,015		11,695		12.00
Risk grade 13	—		—		1,457		400		64		414		1,097		1,566		4,998		13.00
	$	844,354	$	953,664	$	616,642	$	331,729	$	189,719	$	255,999	$	2,331,781	$	60,229	$	5,584,117	6.34
W/A risk grade	6.16		6.87		6.17		6.75		7.00		5.80		6.14		7.82		6.34
Energy
Risk grades 1-8	$	279,051	$	125,435	$	7,519	$	8,444	$	4,068	$	5,665	$	509,657	$	59,424	$	999,263	5.71
Risk grade 9	1,425		103		508		1,407		96		—		5,668		43		9,250		9.00
Risk grade 10	—		—		90		580		351		—		—		515		1,536		10.00
Risk grade 11	9,097		265		512		3,256		951		178		—		—		14,259		11.00
Risk grade 12	—		—		—		3,708		58		—		3,215		98		7,079		12.00
Risk grade 13	—		—		—		1,331		1,079		—		2,782		—		5,192		13.00
	$	289,573	$	125,803	$	8,629	$	18,726	$	6,603	$	5,843	$	521,322	$	60,080	$	1,036,579	5.89
W/A risk grade	6.36		5.77		7.73		9.34		9.24		7.16		5.41		6.31		5.89

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total		W/A Risk Grade
Commercial real estate:
Buildings, land, other
Risk grades 1-8	$	607,883	$	1,554,611	$	1,113,230	$	809,206	$	498,477	$	1,057,840	$	72,704	$	96,924	$	5,810,875	6.89
Risk grade 9	6,163		20,766		108,943		53,448		23,459		45,034		5,516		2,618		265,947		9.00
Risk grade 10	46,125		22,716		7,310		66,821		24,539		57,602		—		—		225,113		10.00
Risk grade 11	—		260		1,293		7,328		6,788		36,699		3,215		—		55,583		11.00
Risk grade 12	—		8,081		296		1,199		394		2,932		—		5,775		18,677		12.00
Risk grade 13	—		326		—		—		—		—		—		—		326		13.00
	$	660,171	$	1,606,760	$	1,231,072	$	938,002	$	553,657	$	1,200,107	$	81,435	$	105,317	$	6,376,521	7.14
W/A risk grade	7.08		7.22		7.04		7.32		7.27		6.97		7.06		6.99		7.14
Construction
Risk grades 1-8	$	202,413	$	634,897	$	195,127	$	141,510	$	636	$	1,842	$	207,182	$	3,666	$	1,387,273	6.96
Risk grade 9	171		28,069		5,359		—		—		423		—		—		34,022		9.00
Risk grade 10	—		—		—		—		—		—		—		—		—		10.00
Risk grade 11	—		—		—		—		—		—		—		—		—		11.00
Risk grade 12	—		—		583		—		—		—		—		—		583		12.00
Risk grade 13	—		—		—		—		—		—		—		—		—		13.00
	$	202,584	$	662,966	$	201,069	$	141,510	$	636	$	2,265	$	207,182	$	3,666	$	1,421,878	7.01
W/A risk grade	6.83		7.28		6.38		7.98		6.22		7.17		6.28		8.00		7.01
Total commercial real estate	$	862,755	$	2,269,726	$	1,432,141	$	1,079,512	$	554,293	$	1,202,372	$	288,617	$	108,983	$	7,798,399	7.11
W/A risk grade	7.02		7.24		6.95		7.41		7.27		6.97		6.50		7.03		7.11

Weighted Average Risk Grades for All Commercial Loans by Class

The following tables present weighted average risk grades for all commercial loans by class as of December 31, 2021. Refer to our 2021 Form 10-K for details of these loans by year of origination/renewal.

	Commercial and Industrial			Energy			Commercial Real Estate - Buildings, Land and Other			Commercial Real Estate - Construction			Total Commercial Real Estate
	W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans		W/A Risk Grade	Loans
Risk grades 1-8	6.01	$	5,063,847	5.78	$	1,008,370	6.91	$	5,574,922	6.99	$	1,262,200	6.92	$	6,837,122
Risk grade 9	9.00	187,870		9.00	36,622		9.00	321,533		9.00	41,123		9.00	362,656
Risk grade 10	10.00	59,137		10.00	1,773		10.00	269,447		10.00	—		10.00	269,447
Risk grade 11	11.00	31,518		11.00	16,594		11.00	91,140		11.00	—		11.00	91,140
Risk grade 12	12.00	12,535		12.00	8,953		12.00	15,097		12.00	748		12.00	15,845
Risk grade 13	13.00	10,047		13.00	5,480		13.00	200		13.00	200		13.00	400
Total	6.22	$	5,364,954	6.06	$	1,077,792	7.22	$	6,272,339	7.06	$	1,304,271	7.19	$	7,576,610

Age analysis of Past Due Consumer Loans by Class and Year of Origination

Information about the payment status of consumer loans, segregated by portfolio segment and year of origination, as of March 31, 2022 was as follows:

	2022		2021		2020		2019		2018		Prior		Revolving Loans		Revolving Loans Converted to Term		Total
Consumer real estate:
Past due 30-89 days	$	—	$	303	$	55	$	465	$	309	$	1,587	$	60	$	1,431	$	4,210
Past due 90 or more days	—		—		4		—		297		854		1,004		250		2,409
Total past due	—		303		59		465		606		2,441		1,064		1,681		6,619
Current loans	51,321		322,814		225,921		86,664		48,481		149,677		533,182		8,946		1,427,006
Total	$	51,321	$	323,117	$	225,980	$	87,129	$	49,087	$	152,118	$	534,246	$	10,627	$	1,433,625
Consumer and other:
Past due 30-89 days	$	1,470	$	385	$	53	$	69	$	54	$	24	$	2,344	$	1,994	$	6,393
Past due 90 or more days	—		499		—		23		—		13		—		58		593
Total past due	1,470		884		53		92		54		37		2,344		2,052		6,986
Current loans	21,692		34,798		13,127		4,936		2,207		2,520		371,266		24,616		475,162
Total	$	23,162	$	35,682	$	13,180	$	5,028	$	2,261	$	2,557	$	373,610	$	26,668	$	482,148

Revolving Loans Converted to Term [Table Text Block]

Revolving loans that converted to term during the three months ended March 31, 2022 and 2021 were as follows:

	Three Months Ended March 31,
	2021		2020
Commercial and industrial	$	5,763	$	11,843
Energy	—		5,928
Commercial real estate:
Buildings, land and other	47		23,303
Construction	3,666		—
Consumer real estate	858		793
Consumer and other	4,222		3,861
Total	$	14,556	$	45,728

Financing Receivable, Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology

The following table presents details of the allowance for credit losses on loans segregated by loan portfolio segment as of March 31, 2022 and December 31, 2021. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA.

March 31, 2022	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Modeled expected credit losses	$	46,635	$	5,971	$	17,110	$	6,260	$	7,634	$	83,610
Q-Factor and other qualitative adjustments	33,916		4,260		111,518		63		1,440		151,197
Specific allocations	6,475		5,191		326		36		—		12,028
Total	$	87,026	$	15,422	$	128,954	$	6,359	$	9,074	$	246,835
December 31, 2021
Modeled expected credit losses	$	46,946	$	6,363	$	16,676	$	6,484	$	6,397	$	82,866
Q-Factor and other qualitative adjustments	14,609		5,374		127,860		65		1,440		149,348
Specific allocations	10,536		5,480		400		36		—		16,452
Total	$	72,091	$	17,217	$	144,936	$	6,585	$	7,837	$	248,666

Activity in Allowance for Loan Losses by Portfolio Segment

The following table details activity in the allowance for credit losses on loans by portfolio segment for the three months ended March 31, 2022 and 2021. Allocation of a portion of the allowance to one category of loans does not preclude its availability to absorb losses in other categories. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA.

	Commercial and Industrial		Energy		Commercial Real Estate		Consumer Real Estate		Consumer and Other		Total
Three months ended:
March 31, 2022
Beginning balance	$	72,091	$	17,217	$	144,936	$	6,585	$	7,837	$	248,666
Credit loss expense (benefit)	17,561		(2,044)		(15,609)		(26)		4,582		4,464
Charge-offs	(3,455)		(371)		(702)		(231)		(5,771)		(10,530)
Recoveries	829		620		329		31		2,426		4,235
Net charge-offs	(2,626)		249		(373)		(200)		(3,345)		(6,295)
Ending balance	$	87,026	$	15,422	$	128,954	$	6,359	$	9,074	$	246,835
March 31, 2021
Beginning balance	$	73,843	$	39,553	$	134,892	$	7,926	$	6,963	$	263,177
Credit loss expense (benefit)	(1,965)		(5,801)		8,922		(2,722)		1,566		—
Charge-offs	(2,189)		(1,433)		—		(284)		(4,060)		(7,966)
Recoveries	1,203		1,153		626		716		2,349		6,047
Net charge-offs	(986)		(280)		626		432		(1,711)		(1,919)
Ending balance	$	70,892	$	33,472	$	144,440	$	5,636	$	6,818	$	261,258

Investment in Loans Related to Allowance for Loan Losses by Portfolio Segment Disaggregated Based on Impairment Methodology

The following table presents loans that were evaluated for expected credit losses on an individual basis and the related specific allocations, by loan portfolio segment as of March 31, 2022 and December 31, 2021.

	March 31, 2022				December 31, 2021
	Loan Balance		Specific Allocations		Loan Balance		Specific Allocations
Commercial and industrial	$	21,529	$	6,475	$	24,523	$	10,536
Energy	11,931		5,191		16,393		5,480
Paycheck Protection Program	—		—		—		—
Commercial real estate:
Buildings, land and other	28,806		326		24,670		200
Construction	—		—		948		200
Consumer real estate	302		36		303		36
Consumer and other	—		—		—		—
Total	$	62,568	$	12,028	$	66,837	$	16,452

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Goodwill and Other Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2022

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets and Goodwill

Goodwill and other intangible assets are presented in the table below.

	March 31, 2022		December 31, 2021
Goodwill	$	654,952	$	654,952
Other intangible assets:
Core deposits	$	591	$	718
Customer relationships	129		148
	$	720	$	866

Estimated Aggregate Future Amortization Expense for Intangible Assets

The estimated aggregate future amortization expense for intangible assets remaining as of March 31, 2022 is as follows:

Remainder of 2022	$	335
2023	282
2024	87
2025	11
2026	5
Thereafter	—
	$	720

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Deposits (Tables)

3 Months Ended

Mar. 31, 2022

Disclosure Text Block [Abstract]

Deposit Liabilities, Type

Deposits were as follows:

	March 31, 2022		December 31, 2021
Non-interest-bearing demand deposits	$	18,114,430	$	18,423,018
Interest-bearing deposits:
Savings and interest checking	12,484,308		11,930,959
Money market accounts	12,490,612		11,228,815
Time accounts	1,341,579		1,112,904
Total interest-bearing deposits	26,316,499		24,272,678
Total deposits	$	44,430,929	$	42,695,696

Additional Information About Corporation's Deposits

The following table presents additional information about our deposits:

	March 31, 2022		December 31, 2021
Deposits from foreign sources (primarily Mexico)	$	1,092,302	$	993,479
Non-interest-bearing public funds deposits	746,097		1,235,026
Interest-bearing public funds deposits	975,511		810,863
Total deposits not covered by deposit insurance	25,213,248		24,125,359
Time deposits not covered by deposit insurance	357,529		238,608

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Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2022

Commitments and Contingencies Disclosure [Abstract]

Financial Instruments with Off-Balance-Sheet Risk

Financial instruments with off-balance-sheet risk were as follows:

	March 31, 2022		December 31, 2021
Commitments to extend credit	$	10,356,196	$	10,420,142
Standby letters of credit	236,798		238,690
Deferred standby letter of credit fees	1,704		2,072

Commitments, Off-Balance-Sheet, Allowance for Credit Losses [Table Text Block]

The following table details activity in the allowance for credit losses on off-balance-sheet credit exposures.

	Three Months Ended March 31,
	2022		2021
Beginning balance	$	50,314	$	44,152
Credit loss expense (benefit)	(4,464)		65
Ending balance	$	45,850	$	44,217

Lease Commitments, Components of Lease Expense [Table Text Block]

We lease certain office facilities and office equipment under operating leases. The components of total lease expense were as follows:

	Three Months Ended March 31,
	2022		2021
Amortization of lease right-of-use assets	$	8,105	$	8,283
Short-term lease expense	613		204
Non-lease components (including taxes, insurance, common maintenance, etc.)	3,020		3,004
Total	$	11,738	$	11,491

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Capital and Regulatory Matters (Tables)

3 Months Ended

Mar. 31, 2022

Banking Regulation, Common Equity Tier One Risk-Based Capital [Abstract]

Actual and Required Capital Ratios

The following table presents actual and required capital ratios as of March 31, 2022 and December 31, 2021 for Cullen/Frost and Frost Bank under the Basel III Capital Rules. Capital levels required to be considered well capitalized are based upon prompt corrective action regulations, as amended to reflect the changes under the Basel III Capital Rules. See the 2021 Form 10-K for a more detailed discussion of the Basel III Capital Rules.

	Actual				Minimum Capital Required - Basel III				Required to be Considered Well Capitalized
	Capital Amount		Ratio		Capital Amount		Ratio		Capital Amount		Ratio
March 31, 2022
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,412,080	12.78	%	$	1,869,007	7.00	%	$	1,735,506	6.50	%
Frost Bank	3,301,515		12.39		1,865,304		7.00		1,732,068		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,557,532		13.32		2,269,508		8.50		2,136,007		8.00
Frost Bank	3,301,515		12.39		2,265,012		8.50		2,131,776		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,998,333		14.97		2,803,510		10.50		2,670,009		10.00
Frost Bank	3,542,316		13.29		2,797,956		10.50		2,664,720		10.00
Leverage Ratio
Cullen/Frost	3,557,532		7.08		2,010,897		4.00		2,513,621		5.00
Frost Bank	3,301,515		6.57		2,009,767		4.00		2,512,209		5.00
December 31, 2021
Common Equity Tier 1 to Risk-Weighted Assets
Cullen/Frost	$	3,371,043	13.13	%	$	1,796,549	7.00	%	$	1,668,224	6.50	%
Frost Bank	3,261,532		12.72		1,795,221		7.00		1,666,991		6.50
Tier 1 Capital to Risk-Weighted Assets
Cullen/Frost	3,516,495		13.70		2,181,523		8.50		2,053,198		8.00
Frost Bank	3,261,532		12.72		2,179,911		8.50		2,051,681		8.00
Total Capital to Risk-Weighted Assets
Cullen/Frost	3,966,244		15.45		2,694,823		10.50		2,566,498		10.00
Frost Bank	3,491,281		13.61		2,692,831		10.50		2,564,601		10.00
Leverage Ratio
Cullen/Frost	3,516,495		7.34		1,917,533		4.00		2,396,917		5.00
Frost Bank	3,261,532		6.80		1,917,679		4.00		2,397,099		5.00

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Derivative Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding

The notional amounts and estimated fair values of interest rate derivative contracts are presented in the following table. The fair values of interest rate derivative contracts are estimated utilizing internal valuation methods with observable market data inputs, or as determined by the Chicago Mercantile Exchange (“CME”) for centrally cleared derivative contracts. CME rules legally characterize variation margin payments for centrally cleared derivatives as settlements of the derivatives' exposure rather than collateral. As a result, the variation margin payment and the related derivative instruments are considered a single unit of account for accounting and financial reporting purposes. Variation margin, as determined by the CME, is settled daily. As a result, derivative contracts that clear through the CME have an estimated fair value of zero as of March 31, 2022 and December 31, 2021.

	March 31, 2022				December 31, 2021
	Notional Amount		Estimated Fair Value		Notional Amount		Estimated Fair Value
Derivatives designated as hedges of fair value:
Financial institution counterparties:
Loan/lease interest rate swaps – assets	$	1,807	$	1	$	—	$	—
Loan/lease interest rate swaps – liabilities	280		(3)		2,426		(34)
Non-hedging interest rate derivatives:
Financial institution counterparties:
Loan/lease interest rate swaps – assets	697,834		15,311		247,592		1,207
Loan/lease interest rate swaps – liabilities	447,742		(6,184)		928,756		(19,142)
Loan/lease interest rate caps – assets	265,930		8,110		270,431		3,239
Customer counterparties:
Loan/lease interest rate swaps – assets	447,742		10,275		928,756		39,864
Loan/lease interest rate swaps – liabilities	697,834		(25,437)		247,592		(2,846)
Loan/lease interest rate caps – liabilities	265,930		(8,110)		270,431		(3,239)

Schedule of Weighted-Average Rates Paid and Received for Interest Rate Swaps Outstanding

The weighted-average rates paid and received for interest rate swaps outstanding at March 31, 2022 were as follows:

	Weighted-Average
	Interest Rate Paid		Interest Rate Received
Interest rate swaps:
Fair value hedge loan/lease interest rate swaps	2.11	%	0.26	%
Non-hedging interest rate swaps – financial institution counterparties	3.69		2.07
Non-hedging interest rate swaps – customer counterparties	2.07		3.69

Schedule of Notional Amounts and Estimated Fair Values of Commodity Derivative Positions

The notional amounts and estimated fair values of non-hedging commodity swap and option derivative positions outstanding are presented in the following table. We obtain dealer quotations and use internal valuation methods with observable market data inputs to value our commodity derivative positions.

		March 31, 2022			December 31, 2021
	Notional Units	Notional Amount	Estimated Fair Value		Notional Amount	Estimated Fair Value
Financial institution counterparties:
Oil – assets	Barrels	2,988	$	9,735	4,809	$	14,721
Oil – liabilities	Barrels	9,767	(189,416)		7,032	(73,594)
Natural gas – assets	MMBTUs	14,564	1,813		15,947	4,143
Natural gas – liabilities	MMBTUs	27,474	(50,244)		29,446	(21,249)
Customer counterparties:
Oil – assets	Barrels	9,767	190,776		7,046	74,437
Oil – liabilities	Barrels	2,988	(9,710)		4,796	(14,294)
Natural gas – assets	MMBTUs	27,474	50,423		29,446	21,456
Natural gas – liabilities	MMBTUs	14,564	(1,811)		15,947	(4,124)

Schedule of Foreign Exchange Contracts, Statement of Financial Position

The notional amounts and fair values of open foreign currency forward contracts were as follows:

		March 31, 2022			December 31, 2021
	Notional Currency	Notional Amount	Estimated Fair Value		Notional Amount	Estimated Fair Value
Financial institution counterparties:
Forward contracts – assets	EUR	2,400	$	18	1,900	$	29
Forward contracts – assets	CAD	—	—		658	—
Forward contracts – liabilities	EUR	6,500	(111)		—	—
Forward contracts – liabilities	CAD	658	(6)		—	—
Customer counterparties:
Forward contracts – assets	EUR	6,500	122		—	—
Forward contracts – assets	CAD	658	10		658	4
Forward contracts – liabilities	EUR	2,400	(14)		1,900	(55)

Schedule of Amounts Related to Interest Rate Derivatives Designated as Hedges of Fair Value

Amounts included in the consolidated statements of income related to interest rate derivatives designated as hedges of fair value were as follows:

	Three Months Ended March 31,
	2022		2021
Commercial loan/lease interest rate swaps:
Amount of gain (loss) included in interest income on loans	$	(13)	$	(28)
Amount of (gain) loss included in other non-interest expense	2		(3)

Schedule of Amounts Related to Non-Hedging Interest Rate and Commodity Derivatives

Amounts included in the consolidated statements of income related to non-hedge related derivative instruments are presented in the table below.

	Three Months Ended March 31,
	2022		2021
Non-hedging interest rate derivatives:
Other non-interest income	$	516	$	1,587
Other non-interest expense	—		(1)
Non-hedging commodity derivatives:
Other non-interest income	929		1,154
Non-hedging foreign currency derivatives:
Other non-interest income	18		30

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Balance Sheet Offsetting (Tables)

3 Months Ended

Mar. 31, 2022

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Financial Instruments Eligible for Offset Consolidated Balance Sheet

Information about financial instruments that are eligible for offset in the consolidated balance sheet as of March 31, 2022 is presented in the following tables.

	Gross Amount Recognized		Gross Amount Offset		Net Amount Recognized
March 31, 2022
Financial assets:
Derivatives:
Loan/lease interest rate swaps and caps	$	23,422	$	—	$	23,422
Commodity swaps and options	11,548		—		11,548
Foreign currency forward contracts	18		—		18
Total derivatives	34,988		—		34,988
Resell agreements	—		—		—
Total	$	34,988	$	—	$	34,988
Financial liabilities:
Derivatives:
Loan/lease interest rate swaps and caps	$	6,187	$	—	$	6,187
Commodity swaps and options	239,660		—		239,660
Foreign currency forward contracts	117		—		117
Total derivatives	245,964		—		245,964
Repurchase agreements	1,842,618		—		1,842,618
Total	$	2,088,582	$	—	$	2,088,582

Information about financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2021 is presented in the following tables.

	Gross Amount Recognized		Gross Amount Offset		Net Amount Recognized
December 31, 2021
Financial assets:
Derivatives:
Loan/lease interest rate swaps and caps	$	4,446	$	—	$	4,446
Commodity swaps and options	18,864		—		18,864
Total derivatives	23,339		—		23,339
Resell agreements	7,903		—		7,903
Total	$	31,242	$	—	$	31,242
Financial liabilities:
Derivatives:
Loan/lease interest rate swaps and caps	$	19,176	$	—	$	19,176
Commodity swaps and options	94,843		—		94,843
Total derivatives	114,019		—		114,019
Repurchase agreements	2,740,799		—		2,740,799
Total	$	2,854,818	$	—	$	2,854,818

Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset

			Gross Amounts Not Offset
	Net Amount Recognized		Financial Instruments		Collateral		Net Amount
March 31, 2022
Financial assets:
Derivatives:
Counterparty A	$	32	$	(32)	$	—	$	—
Counterparty B	11,998		(11,998)		—		—
Other counterparties	22,958		(16,251)		(6,707)		—
Total derivatives	34,988		(28,281)		(6,707)		—
Resell agreements	—		—		—		—
Total	$	34,988	$	(28,281)	$	(6,707)	$	—
Financial liabilities:
Derivatives:
Counterparty A	$	2,635	$	(32)	$	(2,603)	$	—
Counterparty B	46,953		(11,998)		(34,955)		—
Counterparty C	3		—		(3)		—
Other counterparties	196,373		(16,251)		(180,122)		—
Total derivatives	245,964		(28,281)		(217,683)		—
Repurchase agreements	1,842,618		—		(1,842,618)		—
Total	$	2,088,582	$	(28,281)	$	(2,060,301)	$	—

			Gross Amounts Not Offset
	Net Amount Recognized		Financial Instruments		Collateral		Net Amount
December 31, 2021
Financial assets:
Derivatives:
Counterparty A	$	6	$	(6)	$	—	$	—
Counterparty B	7,655		(7,655)		—		—
Other counterparties	15,678		(15,678)		—		—
Total derivatives	23,339		(23,339)		—		—
Resell agreements	7,903		—		(7,903)		—
Total	$	31,242	$	(23,339)	$	(7,903)	$	—
Financial liabilities:
Derivatives:
Counterparty A	$	3,870	$	(6)	$	(3,864)	$	—
Counterparty B	28,130		(7,655)		(20,475)		—
Counterparty C	9		—		(9)		—
Other counterparties	82,010		(15,678)		(66,225)		107
Total derivatives	114,019		(23,339)		(90,573)		107
Repurchase agreements	2,740,799		—		(2,740,799)		—
Total	$	2,854,818	$	(23,339)	$	(2,831,372)	$	107

Remaining Contractual Maturity of the Securities Sold Under Agreement [Table Text Block]

The remaining contractual maturity of repurchase agreements in the consolidated balance sheets as of March 31, 2022 and December 31, 2021 is presented in the following tables.

	Remaining Contractual Maturity of the Agreements
	Overnight and Continuous		Up to 30 Days		30-90 Days		Greater than 90 Days		Total
March 31, 2022
Repurchase agreements:
U.S. Treasury	$	876,879	$	—	$	—	$	—	$	876,879
Residential mortgage-backed securities	965,739		—		—		—		965,739
Total borrowings	$	1,842,618	$	—	$	—	$	—	$	1,842,618
Gross amount of recognized liabilities for repurchase agreements									$	1,842,618
Amounts related to agreements not included in offsetting disclosures above									$	—
December 31, 2021
Repurchase agreements:
U.S. Treasury	$	1,342,591	$	—	$	—	$	—	$	1,342,591
Residential mortgage-backed securities	1,398,208		—		—		—		1,398,208
Total borrowings	$	2,740,799	$	—	$	—	$	—	$	2,740,799
Gross amount of recognized liabilities for repurchase agreements									$	2,740,799
Amounts related to agreements not included in offsetting disclosures above									$	—

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Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award

A combined summary of activity in our active stock plans is presented in the table below. Performance stock units outstanding are presented assuming attainment of the maximum payout rate as set forth by the performance criteria. As of March 31, 2022, there were 794,493 shares remaining available for grant for future stock-based compensation awards.

	Deferred Stock Units Outstanding			Non-Vested Stock Units Outstanding			Performance Stock Units Outstanding			Stock Options Outstanding
	Number of Units	Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant		Number of Units	Weighted- Average Fair Value at Grant		Number of Shares	Weighted- Average Exercise Price
Balance, January 1, 2022	56,301	$	79.21	449,337	$	93.05	202,460	$	84.71	877,681	$	69.02
Authorized	—	—		—	—		—	—		—	—
Granted	—	—		1,038	145.32		—	—		—	—
Exercised/vested	—	—		—	—		(25,180)	87.18		(90,250)	63.59
Forfeited/expired	—	—		(1,786)	89.50		(16,058)	87.18		—	—
Balance, March 31, 2022	56,301	79.21		448,589	93.19		161,222	84.08		787,431	69.64

Shares Issued in Connection with Stock Compensation Awards

Shares issued in connection with stock compensation awards along with other related information were as follows:

	Three Months Ended March 31,
	2022		2021
New shares issued from available authorized shares	—		—
Shares issued from available treasury stock	115,430		513,824
Proceeds from stock option exercises	$	5,739	$	29,397

Share-based Payment Arrangement, Cost by Plan

Stock-based compensation expense or benefit and the related income tax benefit is presented in the following table. The service period for performance stock units granted each year begins on January 1 of the following year.

	Three Months Ended March 31,
	2022		2021
Non-vested stock units	$	2,358	$	1,883
Performance stock units	(246)		643
Total	$	2,112	$	2,526
Income tax benefit	$	708	$	367

Unrecognized Stock-Based Compensation Expense

Unrecognized stock-based compensation expense at March 31, 2022 is presented in the table below. Unrecognized stock-based compensation expense related to performance stock units is presented assuming attainment of the maximum payout rate as set forth by the performance criteria.

Non-vested stock units	$	16,063
Performance stock units	8,664
Total	$	24,727

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Earnings Per Common Share (Tables)

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Basic and Diluted Earnings Per Common Share

The following table presents a reconciliation of net income available to common shareholders, net earnings allocated to common stock and the number of shares used in the calculation of basic and diluted earnings per common share.

	Three Months Ended March 31,
	2022		2021
Net income	$	99,102	$	116,015
Less: Preferred stock dividends	1,669		2,151
Net income available to common shareholders	97,433		113,864
Less: Earnings allocated to participating securities	849		1,162
Net earnings allocated to common stock	$	96,584	$	112,702
Distributed earnings allocated to common stock	$	48,051	$	45,660
Undistributed earnings allocated to common stock	48,533		67,042
Net earnings allocated to common stock	$	96,584	$	112,702
Weighted-average shares outstanding for basic earnings per common share	64,051,202		63,306,493
Dilutive effect of stock compensation	409,705		509,290
Weighted-average shares outstanding for diluted earnings per common share	64,460,907		63,815,783

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Defined Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2022

Retirement Benefits [Abstract]

Net Periodic Cost (Benefit)

The components of the combined net periodic expense (benefit) for our defined benefit pension plans are presented in the table below.

	Three Months Ended March 31,
	2022		2021
Expected return on plan assets, net of expenses	$	(3,491)	$	(3,210)
Interest cost on projected benefit obligation	1,004		835
Net amortization and deferral	741		1,529
Net periodic expense (benefit)	$	(1,746)	$	(846)

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Income Taxes (Tables)

3 Months Ended

Mar. 31, 2022

Income Tax Disclosure [Abstract]

Income Tax Expense

Income tax expense was as follows:

	Three Months Ended March 31,
	2022			2021
Current income tax expense (benefit)	$	13,059		$	3,725
Deferred income tax expense (benefit)	(432)			4,172
Income tax expense, as reported	$	12,627		$	7,897
Effective tax rate	11.3		%	6.4		%

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Other Comprehensive Income (Loss) (Tables)

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Comprehensive Income (Loss)

The before and after tax amounts allocated to each component of other comprehensive income (loss) are presented in the following table. Reclassification adjustments related to securities available for sale are included in net gain (loss) on securities transactions in the accompanying consolidated statements of income. Reclassification adjustments related to defined-benefit post-retirement benefit plans are included in the computation of net periodic pension expense (see Note 12 – Defined Benefit Plans).

	Three Months Ended March 31, 2022						Three Months Ended March 31, 2021
	Before Tax Amount		Tax  Expense, (Benefit)		Net of  Tax Amount		Before Tax Amount		Tax  Expense, (Benefit)		Net of  Tax Amount
Securities available for sale and transferred securities:
Change in net unrealized gain/loss during the period	$	(910,795)	$	(191,267)	$	(719,528)	$	(159,779)	$	(33,554)	$	(126,225)
Change in net unrealized gain on securities transferred to held to maturity	(209)		(44)		(165)		(259)		(54)		(205)
Reclassification adjustment for net (gains) losses included in net income	—		—		—		—		—		—
Total securities available for sale and transferred securities	(911,004)		(191,311)		(719,693)		(160,038)		(33,608)		(126,430)
Defined-benefit post-retirement benefit plans:
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic expense (benefit)	741		156		585		1,529		321		1,208
Total defined-benefit post-retirement benefit plans	741		156		585		1,529		321		1,208
Total other comprehensive income (loss)	$	(910,263)	$	(191,155)	$	(719,108)	$	(158,509)	$	(33,287)	$	(125,222)

Schedule of Accumulated Other Comprehensive Income (Loss)

Activity in accumulated other comprehensive income (loss), net of tax, was as follows:

	Securities Available For Sale		Defined Benefit Plans		Accumulated Other Comprehensive Income
Balance January 1, 2022	$	380,209	$	(32,891)	$	347,318
Other comprehensive income (loss) before reclassifications	(719,693)		—		(719,693)
Reclassification of amounts included in net income	—		585		585
Net other comprehensive income (loss) during period	(719,693)		585		(719,108)
Balance at March 31, 2022	$	(339,484)	$	(32,306)	$	(371,790)
Balance January 1, 2021	$	563,801	$	(50,831)	$	512,970
Other comprehensive income (loss) before reclassifications	(126,430)		—		(126,430)
Reclassification of amounts included in net income	—		1,208		1,208
Net other comprehensive income (loss) during period	(126,430)		1,208		(125,222)
Balance at March 31, 2021	$	437,371	$	(49,623)	$	387,748

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Operating Segments (Tables)

3 Months Ended

Mar. 31, 2022

Segment Reporting [Abstract]

Summary of Operating Results by Segment

Summarized operating results by segment were as follows:

	Banking		Frost  Wealth Advisors		Non-Banks		Consolidated
Three months ended:
March 31, 2022
Net interest income (expense)	$	250,119	$	700	$	(1,748)	$	249,071
Credit loss expense (benefit)	(1)		1		—		—
Non-interest income	58,706		43,229		(545)		101,390
Non-interest expense	206,538		30,910		1,284		238,732
Income (loss) before income taxes	102,288		13,018		(3,577)		111,729
Income tax expense (benefit)	11,014		2,734		(1,121)		12,627
Net income (loss)	91,274		10,284		(2,456)		99,102
Preferred stock dividends	—		—		1,669		1,669
Net income (loss) available to common shareholders	$	91,274	$	10,284	$	(4,125)	$	97,433
Revenues from (expenses to) external customers	$	308,825	$	43,929	$	(2,293)	$	350,461
March 31, 2021
Net interest income (expense)	$	242,205	$	486	$	(1,810)	$	240,881
Credit loss expense	63		—		—		63
Non-interest income	53,780		39,609		(153)		93,236
Non-interest expense	179,151		29,937		1,054		210,142
Income (loss) before income taxes	116,771		10,158		(3,017)		123,912
Income tax expense (benefit)	7,177		2,133		(1,413)		7,897
Net income (loss)	109,594		8,025		(1,604)		116,015
Preferred stock dividends	—		—		2,151		2,151
Net income (loss) available to common shareholders	$	109,594	$	8,025	$	(3,755)	$	113,864
Revenues from (expenses to) external customers	$	295,985	$	40,095	$	(1,963)	$	334,117

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Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis

The tables below summarize financial assets and financial liabilities measured at fair value on a recurring basis as of March 31, 2022 and December 31, 2021, segregated by the level of the valuation inputs within the fair value hierarchy of ASC Topic 820 utilized to measure fair value.

	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
March 31, 2022
Securities available for sale:
U.S. Treasury	$	3,507,746	$	—	$	—	$	3,507,746
Residential mortgage-backed securities	—		5,376,039		—		5,376,039
States and political subdivisions	—		7,258,393		—		7,258,393
Other	—		42,361		—		42,361
Trading account securities:
U.S. Treasury	23,939		—		—		23,939
States and political subdivisions	—		5,579		—		5,579
Derivative assets:
Interest rate swaps, caps and floors	—		33,697		—		33,697
Commodity swaps and options	—		252,747		—		252,747
Foreign currency forward contracts	150		—		—		150
Derivative liabilities:
Interest rate swaps, caps and floors	—		39,734		—		39,734
Commodity swaps and options	—		251,181		—		251,181
Foreign currency forward contracts	131		—		—		131
December 31, 2021
Securities available for sale:
U.S. Treasury	$	2,179,433	$	—	$	—	$	2,179,433
Residential mortgage-backed securities	—		4,066,265		—		4,066,265
States and political subdivisions	—		7,636,571		—		7,636,571
Other	—		42,359		—		42,359
Trading account securities:
U.S. Treasury	24,237		—		—		24,237
States and political subdivisions	—		925		—		925
Derivative assets:
Interest rate swaps, caps and floors	—		44,310		—		44,310
Commodity swaps and options	—		114,757		—		114,757
Foreign currency forward contracts	33		—		—		33
Derivative liabilities:
Interest rate swaps, caps and floors	—		25,261		—		25,261
Commodity swaps and options	—		113,261		—		113,261
Foreign currency forward contracts	55		—		—		55

Impaired Loans Remeasured And Reported At Fair Value Specific Valuation Allowance Allocation Method Of Underlying Collateral [Table Text Block]

The following table presents collateral dependent loans that were remeasured and reported at fair value through a specific allocation of the allowance for credit losses on loans based upon the fair value of the underlying collateral during the reported periods.

	Three Months Ended March 31, 2022				Three Months Ended March 31, 2021
	Level 2		Level 3		Level 2		Level 3
Carrying value before allocations	$	2,064	$	5,711	$	100	$	15,013
Specific (allocations) reversals of prior allocations	(126)		3,965		—		600
Fair value	$	1,938	$	9,676	$	100	$	15,613

Estimated Fair Values of Financial Instruments

The estimated fair values of financial instruments that are reported at amortized cost in our consolidated balance sheets, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value, were as follows:

	March 31, 2022				December 31, 2021
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Financial assets:
Level 2 inputs:
Cash and cash equivalents	$	14,457,083	$	14,457,083	$	16,583,000	$	16,583,000
Securities held to maturity	1,665,465		1,639,993		1,749,179		1,809,143
Cash surrender value of life insurance policies	189,471		189,471		190,139		190,139
Accrued interest receivable	131,370		131,370		179,111		179,111
Level 3 inputs:
Loans, net	16,295,702		16,053,955		16,087,731		16,079,454
Financial liabilities:
Level 2 inputs:
Deposits	44,430,929		44,422,700		42,695,696		41,343,426
Federal funds purchased	35,200		35,200		25,925		25,925
Repurchase agreements	1,842,618		1,842,618		2,740,799		2,740,799
Junior subordinated deferrable interest debentures	123,026		123,712		123,011		123,712
Subordinated notes	99,217		105,740		99,178		111,430
Accrued interest payable	2,147		2,147		3,026		3,026

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Significant Accounting Policies - Additional Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounting Policies [Abstract]
Cash paid for interest	$ 8,069	$ 9,719
Cash paid for income taxes	0	0
Unsettled securities transactions	78,769	21,957
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities	4,013	1,326
Treasury stock issued to 401(k) stock purchase plan	$ 0	$ 1,749

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Securities - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule Of Marketable Securities [Line Items]
AOCI, Debt Securities, Available-for-sale, Adjustment, Pre Tax	$ 2,300		$ 2,500
Net unamortized unrealized gain on transferred securities included in accumulated other comprehensive income, net of tax	$ 1,800		2,000
Percent Municipal Bond Portfolio Issued By Political Subdivision Or Agencies Within State Of Texas Guaranteed By Texas Permanent School Fund Or Have Been Pre-Refunded	75.70%
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0		0
Proceeds from Sale of Debt Securities, Available-for-sale	0	$ 0
Proceeds from Sale of Held-to-maturity Securities	0	$ 0
Held-to-maturity Securities [Member]
Schedule Of Marketable Securities [Line Items]
Carry value of securities pledged	252,000		642,300
Accrued interest receivable	10,000		18,400
Available-for-sale Securities [Member]
Schedule Of Marketable Securities [Line Items]
Carry value of securities pledged	4,800,000		5,800,000
Accrued interest receivable	$ 80,800		$ 120,500

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Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Held to Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	$ 1,665,623	$ 1,749,337
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	3,622	59,907
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	29,252	101
Debt Securities, Held-to-maturity, Fair Value	1,639,993	1,809,143
Securities, held-to-maturity, allowance for credit loss	(158)	(158)
Securities held to maturity, net of allowance for credit losses of $158 at March 31, 2022 and $158 at December 31, 2021	1,665,465	1,749,179
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	526,969	527,264
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	18,766
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	17,519	0
Debt Securities, Held-to-maturity, Fair Value	509,450	546,030
Securities, held-to-maturity, allowance for credit loss	0	0
Securities held to maturity, net of allowance for credit losses of $158 at March 31, 2022 and $158 at December 31, 2021	526,969	527,264
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	1,137,154	1,220,573
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	3,622	41,141
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	11,717	101
Debt Securities, Held-to-maturity, Fair Value	1,129,059	1,261,613
Securities, held-to-maturity, allowance for credit loss	(158)	(158)
Securities held to maturity, net of allowance for credit losses of $158 at March 31, 2022 and $158 at December 31, 2021	1,136,996	1,220,415
Other Investments [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	1,500	1,500
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	16	0
Debt Securities, Held-to-maturity, Fair Value	1,484	1,500
Securities, held-to-maturity, allowance for credit loss	0	0
Securities held to maturity, net of allowance for credit losses of $158 at March 31, 2022 and $158 at December 31, 2021	$ 1,500	$ 1,500

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Securities Securities - Moody's and/or Standard & Poor's Bond Rating (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 1,665,623	$ 1,749,337
US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,137,154	1,220,573
Other Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,500	1,500
Aaa/AAA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,029,256	1,116,278
Aaa/AAA [Member] | Other Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Aa/AA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	107,898	104,295
Aa/AA [Member] | Other Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Not rated [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Not rated [Member] | Other Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,500	1,500
Not Guaranteed or Pre-Refunded [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	198,932	196,674
Not Guaranteed or Pre-Refunded [Member] | Aaa/AAA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	91,034	92,379
Not Guaranteed or Pre-Refunded [Member] | Aa/AA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	107,898	104,295
Not Guaranteed or Pre-Refunded [Member] | Not rated [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Guaranteed by the Texas PSF [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	467,039	460,648
Guaranteed by the Texas PSF [Member] | Aaa/AAA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	467,039	460,648
Guaranteed by the Texas PSF [Member] | Aa/AA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Guaranteed by the Texas PSF [Member] | Not rated [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Pre-Refunded [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	471,183	563,251
Pre-Refunded [Member] | Aaa/AAA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	471,183	563,251
Pre-Refunded [Member] | Aa/AA [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Pre-Refunded [Member] | Not rated [Member] | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 0	$ 0

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Securities Securities - Allowance for Credit Losses on Held to Maturity Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Securities, held-to-maturity, allowance for credit loss	$ 158		$ 158
Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities, held-to-maturity, allowance for credit loss	158	$ 158	$ 158	$ 160
Credit loss expense (benefit)	$ 0	$ (2)

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Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 16,616,594	$ 13,445,888
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	144,335	518,805
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	576,390	40,065
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	16,184,539	13,924,628
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	3,658,506	2,165,702
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,883	23,333
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	152,643	9,602
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	3,507,746	2,179,433
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,696,906	4,059,692
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	7,246	31,662
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	328,113	25,089
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	5,376,039	4,066,265
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	7,218,821	7,178,135
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	135,206	463,810
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	95,634	5,374
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	7,258,393	7,636,571
Other Investments [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	42,361	42,359
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	$ 42,361	$ 42,359

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Securities - Securities Available for Sale, with Unrealized Losses Segregated by Length of Impairment (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Available-for-Sale Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 9,037,646
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	532,200
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	416,542
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	44,190
Debt Securities, Available-for-sale, Unrealized Loss Position	9,454,188
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	576,390	$ 40,065
U.S. Treasury [Member]
Schedule of Available-for-Sale Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	3,220,375
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	152,643
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Debt Securities, Available-for-sale, Unrealized Loss Position	3,220,375
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	152,643	9,602
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-Sale Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	4,583,657
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	286,421
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	402,940
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	41,692
Debt Securities, Available-for-sale, Unrealized Loss Position	4,986,597
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	328,113	25,089
States and political subdivisions [Member]
Schedule of Available-for-Sale Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	1,233,614
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	93,136
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	13,602
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,498
Debt Securities, Available-for-sale, Unrealized Loss Position	1,247,216
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 95,634	$ 5,374

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Securities - Amortized Cost and Estimated Fair Value of Securities, Excluding Trading Securities, Presented by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	$ 429,868
Held to Maturity, Due after one year through five years, Amortized Cost	120,016
Held to Maturity, Due after five years through ten years, Amortized Cost	571,577
Held to Maturity, Due after ten years, Amortized Cost	544,162
Held to Maturity, Amortized Cost	1,665,623	$ 1,749,337
Held to Maturity, Due in one year or less, Estimated Fair Value	431,977
Held to Maturity, Due after one year through five years, Estimated Fair Value	121,182
Held to Maturity, Due after five years through ten years, Estimated Fair Value	555,051
Held to Maturity, Due after ten years, Estimated Fair Value	531,783
Held to Maturity, Estimated Fair Value	1,639,993	1,809,143
Available-for-sale Securities, Due in one year or less, Amortized Cost	194,518
Available for Sale, Due after one year through five years, Amortized Cost	3,610,741
Available for Sale, Due after five years through ten years, Amortized Cost	2,340,280
Available for Sale, Due after ten years, Amortized Cost	10,428,694
Debt Securities, Available-for-sale, Amortized Cost	16,616,594	13,445,888
Available for Sale, Due in one year or less, Estimated Fair Value	197,334
Available for Sale, Due after one year through five years, Estimated Fair Value	3,596,062
Available for Sale, Due after five years through ten years, Estimated Fair Value	2,269,482
Available for Sale, Due after ten years, Estimated Fair Value	10,079,300
Securities available for sale, at estimated fair value	16,184,539	13,924,628
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Due in one year or less, Amortized Cost	0
Available for Sale, Due after one year through five years, Amortized Cost	2,033,995
Available for Sale, Due after five years through ten years, Amortized Cost	1,432,731
Available for Sale, Due after ten years, Amortized Cost	191,780
Debt Securities, Available-for-sale, Amortized Cost	3,658,506	2,165,702
Available for Sale, Due in one year or less, Estimated Fair Value	0
Available for Sale, Due after one year through five years, Estimated Fair Value	1,978,865
Available for Sale, Due after five years through ten years, Estimated Fair Value	1,350,553
Available for Sale, Due after ten years, Estimated Fair Value	178,328
Securities available for sale, at estimated fair value	3,507,746	2,179,433
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	16
Held to Maturity, Due after one year through five years, Amortized Cost	0
Held to Maturity, Due after five years through ten years, Amortized Cost	514,842
Held to Maturity, Due after ten years, Amortized Cost	12,111
Held to Maturity, Amortized Cost	526,969	527,264
Held to Maturity, Due in one year or less, Estimated Fair Value	16
Held to Maturity, Due after one year through five years, Estimated Fair Value	0
Held to Maturity, Due after five years through ten years, Estimated Fair Value	498,078
Held to Maturity, Due after ten years, Estimated Fair Value	11,356
Held to Maturity, Estimated Fair Value	509,450	546,030
Available-for-sale Securities, Due in one year or less, Amortized Cost	102
Available for Sale, Due after one year through five years, Amortized Cost	12,917
Available for Sale, Due after five years through ten years, Amortized Cost	19,060
Available for Sale, Due after ten years, Amortized Cost	5,664,827
Debt Securities, Available-for-sale, Amortized Cost	5,696,906	4,059,692
Available for Sale, Due in one year or less, Estimated Fair Value	103
Available for Sale, Due after one year through five years, Estimated Fair Value	13,212
Available for Sale, Due after five years through ten years, Estimated Fair Value	19,327
Available for Sale, Due after ten years, Estimated Fair Value	5,343,397
Securities available for sale, at estimated fair value	5,376,039	4,066,265
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	429,852
Held to Maturity, Due after one year through five years, Amortized Cost	118,516
Held to Maturity, Due after five years through ten years, Amortized Cost	56,735
Held to Maturity, Due after ten years, Amortized Cost	532,051
Held to Maturity, Amortized Cost	1,137,154	1,220,573
Held to Maturity, Due in one year or less, Estimated Fair Value	431,961
Held to Maturity, Due after one year through five years, Estimated Fair Value	119,698
Held to Maturity, Due after five years through ten years, Estimated Fair Value	56,973
Held to Maturity, Due after ten years, Estimated Fair Value	520,427
Held to Maturity, Estimated Fair Value	1,129,059	1,261,613
Available-for-sale Securities, Due in one year or less, Amortized Cost	194,416
Available for Sale, Due after one year through five years, Amortized Cost	1,563,829
Available for Sale, Due after five years through ten years, Amortized Cost	888,489
Available for Sale, Due after ten years, Amortized Cost	4,572,087
Debt Securities, Available-for-sale, Amortized Cost	7,218,821	7,178,135
Available for Sale, Due in one year or less, Estimated Fair Value	197,231
Available for Sale, Due after one year through five years, Estimated Fair Value	1,603,985
Available for Sale, Due after five years through ten years, Estimated Fair Value	899,602
Available for Sale, Due after ten years, Estimated Fair Value	4,557,575
Securities available for sale, at estimated fair value	7,258,393	7,636,571
Other Investments [Member]
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	0
Held to Maturity, Due after one year through five years, Amortized Cost	1,500
Held to Maturity, Due after five years through ten years, Amortized Cost	0
Held to Maturity, Due after ten years, Amortized Cost	0
Held to Maturity, Amortized Cost	1,500	1,500
Held to Maturity, Due in one year or less, Estimated Fair Value	0
Held to Maturity, Due after one year through five years, Estimated Fair Value	1,484
Held to Maturity, Due after five years through ten years, Estimated Fair Value	0
Held to Maturity, Due after ten years, Estimated Fair Value	0
Held to Maturity, Estimated Fair Value	1,484	1,500
Available-for-sale Securities, Due in one year or less, Amortized Cost	0
Available for Sale, Due after one year through five years, Amortized Cost	0
Available for Sale, Due after five years through ten years, Amortized Cost	0
Available for Sale, Due after ten years, Amortized Cost	0
Debt Securities, Available-for-sale, Amortized Cost	42,361	42,359
Available for Sale, Due in one year or less, Estimated Fair Value	0
Available for Sale, Due after one year through five years, Estimated Fair Value	0
Available for Sale, Due after five years through ten years, Estimated Fair Value	0
Available for Sale, Due after ten years, Estimated Fair Value	0
Securities available for sale, at estimated fair value	$ 42,361	$ 42,359

XML

Securities Securities - Premium Amortization and Discount Accretion Included in Income on Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Premium amortization	$ (29,060)	$ (31,235)
Discount accretion	1,406	637
Net (premium amortization) discount accretion	$ (27,654)	$ (30,598)

XML

Securities - Trading Account Securities, at Estimated Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	$ 29,518	$ 25,162
U.S. Treasury [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	23,939	24,237
States and political subdivisions [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	$ 5,579	$ 925

XML

Securities - Net Gains and Losses on Trading Account Securities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Net gain on sales transactions	$ 340	$ 109
Net mark-to-market gains (losses)	(168)	(69)
Net gain (loss) on trading account securities	$ 172	$ 40

XML

Loans - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration of loans in a single industry in excess of ten percent	0.00%
Maximum percentage loan related to single industry	10.00%
U.S. dollar denominated loans and commitments to borrowers in Mexico	$ 0		$ 0
Loans and Leases Receivable, Related Parties	346,500		$ 350,500
Loans modified as troubled debt restructurings	$ 0	$ 0
Texas Leading Index economic condition indicator	141.2		135.9
Financing Receivable, Allowance for Credit Loss	$ 246,835		$ 248,666
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total energy loans to total loans	6.30%
Percentage of total energy loans to total loans excluding PPP Loans	6.30%
Financing Receivable, Allowance for Credit Loss	$ 15,422	33,472	17,217	$ 39,553
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	0	0	0
Non Accrual Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Additional interest that would have been recognized on non-accrual loans, net of tax	407	$ 453
Commitments to Extend Credit [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	862,200
Standby Letters of Credit [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	76,000
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable	$ 39,500		$ 40,000

XML

Loans - Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 16,542,537	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	5,584,117	5,364,954
Energy Production [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	820,107	878,436
Energy Service [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	113,708	105,901
Energy Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	102,764	93,455
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	1,036,579	1,077,792
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	207,669	428,882
Commercial mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	5,918,011	5,867,062
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	1,421,878	1,304,271
Commercial land loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	458,510	405,277
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	7,798,399	7,576,610
Home Equity Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	321,842	324,157
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	544,822	519,098
Other consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	566,961	567,535
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	1,433,625	1,410,790
Real Estate Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	9,232,024	8,987,400
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 482,148	$ 477,369

XML

Loans - Non-Accrual Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 48,966	$ 53,713
Non-accrual with no credit loss allowance	30,749	27,202
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	16,693	22,582
Non-accrual with no credit loss allowance	6,135	4,701
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	12,271	14,433
Non-accrual with no credit loss allowance	6,912	8,533
Paycheck Protection Program [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	0
Non-accrual with no credit loss allowance	0	0
Commercial Real Estate Buildings Land And Other Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	19,003	15,297
Non-accrual with no credit loss allowance	17,005	13,817
Construction Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	583	948
Non-accrual with no credit loss allowance	583	0
Total consumer real estate loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	416	440
Non-accrual with no credit loss allowance	114	138
Consumer Loan [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	13
Non-accrual with no credit loss allowance	$ 0	$ 13

XML

Loans Loans - Non-Accrual Loans, Segregated by Class of Loans and Year of Origination (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 48,966	$ 53,713
Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8,885
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,980
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	10,148
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,083
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,355
Financing Receivable, Revolving	8,035
Financing Receivable, Revolving, Converted to Term Loan	9,480
Commercial Portfolio Segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	844,354
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	953,664
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	616,642
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	331,729
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	189,719
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	255,999
Financing Receivable, Revolving	2,331,781
Non-accrual loans	16,693	22,582
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	478
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,101
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,910
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,552
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,033
Financing Receivable, Revolving	2,038
Financing Receivable, Revolving, Converted to Term Loan	3,581
Commercial and Industrial Total Energy Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	289,573
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	125,803
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	8,629
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	18,726
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,603
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,843
Financing Receivable, Revolving	521,322
Non-accrual loans	12,271	14,433
Commercial and Industrial Total Energy Loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	5,039
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,137
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	5,997
Financing Receivable, Revolving, Converted to Term Loan	98
Paycheck Protection Program [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	0	0
Paycheck Protection Program [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Commercial Real Estate Buildings Land And Other Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	660,171
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,606,760
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,231,072
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	938,002
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	553,657
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,200,107
Financing Receivable, Revolving	81,435
Non-accrual loans	19,003	15,297
Commercial Real Estate Buildings Land And Other Loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8,407
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	296
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,199
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	394
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,932
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	5,775
Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	202,584
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	662,966
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	201,069
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	141,510
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	636
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,265
Financing Receivable, Revolving	207,182
Non-accrual loans	583	948
Construction Loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	583
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Total consumer real estate loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	416	440
Total consumer real estate loans [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	390
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	26
Consumer Loan [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	0	$ 13
Consumer Loan [Member] | Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	$ 0

XML

Loans - Age Analysis of Past Due Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Total loans	$ 16,542,537	$ 16,336,397
Accruing Loans 90 or More Days Past Due	16,572
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total loans	5,584,117	5,364,954
Accruing Loans 90 or More Days Past Due	4,166
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	1,036,579	1,077,792
Accruing Loans 90 or More Days Past Due	287
Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Total loans	207,669	428,882
Accruing Loans 90 or More Days Past Due	8,377
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	6,376,521	6,272,339
Accruing Loans 90 or More Days Past Due	1,046
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	1,421,878	1,304,271
Accruing Loans 90 or More Days Past Due	0
Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	1,433,625	1,410,790
Accruing Loans 90 or More Days Past Due	2,103
Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Total loans	482,148	$ 477,369
Accruing Loans 90 or More Days Past Due	593
Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	47,820
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	13,016
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
Financing Receivables, 30 to 89 Days Past Due [Member] | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	671
Financing Receivables, 30 to 89 Days Past Due [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	21,542
Financing Receivables, 30 to 89 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,988
Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,210
Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,393
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	37,349
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	8,042
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,382
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	8,377
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	11,546
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,409
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	593
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	85,169
Financial Asset, Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	21,058
Financial Asset, Past Due | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,382
Financial Asset, Past Due | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,048
Financial Asset, Past Due | Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	33,088
Financial Asset, Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,988
Financial Asset, Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,619
Financial Asset, Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,986
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	16,457,368
Financial Asset, Not Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,563,059
Financial Asset, Not Past Due | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,030,197
Financial Asset, Not Past Due | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	198,621
Financial Asset, Not Past Due | Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,343,433
Financial Asset, Not Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,419,890
Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,427,006
Financial Asset, Not Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 475,162

XML

Loans Loans - Restructured Loans Past Due in Excess of 90 Days on Financing Receivables (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) Item	Mar. 31, 2021 USD ($) Item
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number Of Restructured Loans Past Due In Excess of 90 Days At Period-End | Item	2	2
Dollar amount of previously restructured loans past due	$ 572	$ 1,392
Charge-offs of restructured loans recognized on previously restructured loans	$ 723	$ 1,433

XML

Loans Loans - Weighted Average Risk Grade for All Commercial Loans by Class and Year of Origination (Details) $ in Thousands	Mar. 31, 2022 USD ($) Grade	Dec. 31, 2021 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,542,537	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	844,354
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	953,664
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	616,642
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	331,729
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	189,719
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	255,999
Financing Receivable, Revolving	2,331,781
Loans and Leases Receivable, Net of Deferred Income	$ 5,584,117	$ 5,364,954
Weighted Average Risk Grade For Loans | Grade	6.34	6.22
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 289,573
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	125,803
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	8,629
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	18,726
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,603
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,843
Financing Receivable, Revolving	521,322
Loans and Leases Receivable, Net of Deferred Income	$ 1,036,579	$ 1,077,792
Weighted Average Risk Grade For Loans | Grade	5.89	6.06
Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 660,171
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,606,760
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,231,072
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	938,002
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	553,657
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,200,107
Financing Receivable, Revolving	81,435
Loans and Leases Receivable, Net of Deferred Income	$ 6,376,521	$ 6,272,339
Weighted Average Risk Grade For Loans | Grade	7.14	7.22
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 202,584
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	662,966
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	201,069
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	141,510
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	636
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,265
Financing Receivable, Revolving	207,182
Loans and Leases Receivable, Net of Deferred Income	$ 1,421,878	$ 1,304,271
Weighted Average Risk Grade For Loans | Grade	7.01	7.06
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 862,755
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,269,726
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,432,141
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,079,512
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	554,293
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,202,372
Financing Receivable, Revolving	288,617
Loans and Leases Receivable, Net of Deferred Income	$ 7,798,399	$ 7,576,610
Weighted Average Risk Grade For Loans | Grade	7.11	7.19
Risk Grade One To Eight [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 836,152
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	894,663
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	592,780
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	305,667
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	160,622
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	243,869
Financing Receivable, Revolving	2,255,878
Loans and Leases Receivable, Net of Deferred Income	$ 5,334,409	$ 5,063,847
Weighted Average Risk Grade For Loans | Grade	6.18	6.01
Risk Grade One To Eight [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 279,051
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	125,435
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	7,519
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8,444
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4,068
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,665
Financing Receivable, Revolving	509,657
Loans and Leases Receivable, Net of Deferred Income	$ 999,263	$ 1,008,370
Weighted Average Risk Grade For Loans | Grade	5.71	5.78
Risk Grade One To Eight [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 607,883
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,554,611
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,113,230
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	809,206
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	498,477
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,057,840
Financing Receivable, Revolving	72,704
Loans and Leases Receivable, Net of Deferred Income	$ 5,810,875	$ 5,574,922
Weighted Average Risk Grade For Loans | Grade	6.89	6.91
Risk Grade One To Eight [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 202,413
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	634,897
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	195,127
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	141,510
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	636
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,842
Financing Receivable, Revolving	207,182
Loans and Leases Receivable, Net of Deferred Income	$ 1,387,273	$ 1,262,200
Weighted Average Risk Grade For Loans | Grade	6.96	6.99
Risk Grade One To Eight [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 6,837,122
Weighted Average Risk Grade For Loans | Grade		6.92
Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 4,702
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	34,513
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,562
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	11,434
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	21,841
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	8,319
Financing Receivable, Revolving	54,008
Loans and Leases Receivable, Net of Deferred Income	$ 146,100	$ 187,870
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Risk Grade Nine [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,425
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	103
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	508
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,407
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	96
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	5,668
Loans and Leases Receivable, Net of Deferred Income	$ 9,250	$ 36,622
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Risk Grade Nine [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 6,163
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	20,766
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	108,943
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	53,448
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	23,459
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	45,034
Financing Receivable, Revolving	5,516
Loans and Leases Receivable, Net of Deferred Income	$ 265,947	$ 321,533
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 171
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	28,069
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	5,359
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	423
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 34,022	$ 41,123
Weighted Average Risk Grade For Loans | Grade	9.00	9.00
Risk Grade Nine [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 362,656
Weighted Average Risk Grade For Loans | Grade		9.00
Risk Grade Ten [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 3,500
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	22,084
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,527
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,039
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4,007
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	578
Financing Receivable, Revolving	13,899
Loans and Leases Receivable, Net of Deferred Income	$ 52,832	$ 59,137
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Risk Grade Ten [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	90
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	580
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	351
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 1,536	$ 1,773
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Risk Grade Ten [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 46,125
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	22,716
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	7,310
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	66,821
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	24,539
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	57,602
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 225,113	$ 269,447
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 0
Weighted Average Risk Grade For Loans | Grade	10.00	10.00
Risk Grade Ten [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 269,447
Weighted Average Risk Grade For Loans | Grade		10.00
Risk Grade Eleven [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,926
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,672
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	9,679
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,697
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,200
Financing Receivable, Revolving	5,958
Loans and Leases Receivable, Net of Deferred Income	$ 34,083	$ 31,518
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Risk Grade Eleven [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 9,097
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	265
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	512
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,256
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	951
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	178
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 14,259	$ 16,594
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Risk Grade Eleven [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	260
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,293
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	7,328
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,788
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	36,699
Financing Receivable, Revolving	3,215
Loans and Leases Receivable, Net of Deferred Income	$ 55,583	$ 91,140
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 0
Weighted Average Risk Grade For Loans | Grade	11.00	11.00
Risk Grade Eleven [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 91,140
Weighted Average Risk Grade For Loans | Grade		11.00
Risk Grade Twelve [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	478
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,644
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,510
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,488
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	619
Financing Receivable, Revolving	941
Loans and Leases Receivable, Net of Deferred Income	$ 11,695	$ 12,535
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Risk Grade Twelve [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,708
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	58
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	3,215
Loans and Leases Receivable, Net of Deferred Income	$ 7,079	$ 8,953
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Risk Grade Twelve [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8,081
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	296
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,199
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	394
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,932
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 18,677	$ 15,097
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	583
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 583	$ 748
Weighted Average Risk Grade For Loans | Grade	12.00	12.00
Risk Grade Twelve [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 15,845
Weighted Average Risk Grade For Loans | Grade		12.00
Risk Grade Thirteen [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,457
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	400
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	64
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	414
Financing Receivable, Revolving	1,097
Loans and Leases Receivable, Net of Deferred Income	$ 4,998	$ 10,047
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Risk Grade Thirteen [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,331
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,079
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	2,782
Loans and Leases Receivable, Net of Deferred Income	$ 5,192	$ 5,480
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Risk Grade Thirteen [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	326
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 326	$ 200
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 200
Weighted Average Risk Grade For Loans | Grade	13.00	13.00
Risk Grade Thirteen [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income		$ 400
Weighted Average Risk Grade For Loans | Grade		13.00
Revolving Credit Facility [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.14
Revolving Credit Facility [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.41
Revolving Credit Facility [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.06
Revolving Credit Facility [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.28
Revolving Credit Facility [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.50
Revolving Loans Converted to Term [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 60,229
Weighted Average Risk Grade For Loans | Grade	7.82
Revolving Loans Converted to Term [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 60,080
Weighted Average Risk Grade For Loans | Grade	6.31
Revolving Loans Converted to Term [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 105,317
Weighted Average Risk Grade For Loans | Grade	6.99
Revolving Loans Converted to Term [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 3,666
Weighted Average Risk Grade For Loans | Grade	8.00
Revolving Loans Converted to Term [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 108,983
Weighted Average Risk Grade For Loans | Grade	7.03
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 44,778
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	59,424
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	96,924
Revolving Loans Converted to Term [Member] | Risk Grade One To Eight [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	3,666
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	4,721
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	43
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	2,618
Revolving Loans Converted to Term [Member] | Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	1,198
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	515
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	5,951
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	2,015
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	98
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	5,775
Revolving Loans Converted to Term [Member] | Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	1,566
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 0
2022 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.16
2022 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.36
2022 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.08
2022 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.83
2022 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.02
2021 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.87
2021 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.77
2021 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.22
2021 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.28
2021 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.24
2020 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.17
2020 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.73
2020 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.04
2020 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.38
2020 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.95
2019 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.75
2019 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	9.34
2019 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.32
2019 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.98
2019 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.41
2018 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.00
2018 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	9.24
2018 [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.27
2018 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.22
2018 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.27
Prior Years [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.80
Prior Years [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.16
Prior Years [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.97
Prior Years [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.17
Prior Years [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.97

XML

Loans - Weighted Average Risk Grades for All Commercial Loans by Class (Detail) $ in Thousands	Mar. 31, 2022 USD ($) Grade	Dec. 31, 2021 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,542,537	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.34	6.22
Loans and Leases Receivable, Net of Deferred Income	$ 5,584,117	$ 5,364,954
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	5.89	6.06
Loans and Leases Receivable, Net of Deferred Income	$ 1,036,579	$ 1,077,792
Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.14	7.22
Loans and Leases Receivable, Net of Deferred Income	$ 6,376,521	$ 6,272,339
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.01	7.06
Loans and Leases Receivable, Net of Deferred Income	$ 1,421,878	$ 1,304,271
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.11	7.19
Loans and Leases Receivable, Net of Deferred Income	$ 7,798,399	$ 7,576,610
Risk Grade One To Eight [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.18	6.01
Loans and Leases Receivable, Net of Deferred Income	$ 5,334,409	$ 5,063,847
Risk Grade One To Eight [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	5.71	5.78
Loans and Leases Receivable, Net of Deferred Income	$ 999,263	$ 1,008,370
Risk Grade One To Eight [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.89	6.91
Loans and Leases Receivable, Net of Deferred Income	$ 5,810,875	$ 5,574,922
Risk Grade One To Eight [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.96	6.99
Loans and Leases Receivable, Net of Deferred Income	$ 1,387,273	$ 1,262,200
Risk Grade One To Eight [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade		6.92
Loans and Leases Receivable, Net of Deferred Income		$ 6,837,122
Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	9.00	9.00
Loans and Leases Receivable, Net of Deferred Income	$ 146,100	$ 187,870
Risk Grade Nine [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	9.00	9.00
Loans and Leases Receivable, Net of Deferred Income	$ 9,250	$ 36,622
Risk Grade Nine [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	9.00	9.00
Loans and Leases Receivable, Net of Deferred Income	$ 265,947	$ 321,533
Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	9.00	9.00
Loans and Leases Receivable, Net of Deferred Income	$ 34,022	$ 41,123
Risk Grade Nine [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade		9.00
Loans and Leases Receivable, Net of Deferred Income		$ 362,656
Risk Grade Ten [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	10.00	10.00
Loans and Leases Receivable, Net of Deferred Income	$ 52,832	$ 59,137
Risk Grade Ten [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	10.00	10.00
Loans and Leases Receivable, Net of Deferred Income	$ 1,536	$ 1,773
Risk Grade Ten [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	10.00	10.00
Loans and Leases Receivable, Net of Deferred Income	$ 225,113	$ 269,447
Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	10.00	10.00
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 0
Risk Grade Ten [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade		10.00
Loans and Leases Receivable, Net of Deferred Income		$ 269,447
Risk Grade Eleven [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	11.00	11.00
Loans and Leases Receivable, Net of Deferred Income	$ 34,083	$ 31,518
Risk Grade Eleven [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	11.00	11.00
Loans and Leases Receivable, Net of Deferred Income	$ 14,259	$ 16,594
Risk Grade Eleven [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	11.00	11.00
Loans and Leases Receivable, Net of Deferred Income	$ 55,583	$ 91,140
Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	11.00	11.00
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 0
Risk Grade Eleven [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade		11.00
Loans and Leases Receivable, Net of Deferred Income		$ 91,140
Risk Grade Twelve [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	12.00	12.00
Loans and Leases Receivable, Net of Deferred Income	$ 11,695	$ 12,535
Risk Grade Twelve [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	12.00	12.00
Loans and Leases Receivable, Net of Deferred Income	$ 7,079	$ 8,953
Risk Grade Twelve [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	12.00	12.00
Loans and Leases Receivable, Net of Deferred Income	$ 18,677	$ 15,097
Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	12.00	12.00
Loans and Leases Receivable, Net of Deferred Income	$ 583	$ 748
Risk Grade Twelve [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade		12.00
Loans and Leases Receivable, Net of Deferred Income		$ 15,845
Risk Grade Thirteen [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	13.00	13.00
Loans and Leases Receivable, Net of Deferred Income	$ 4,998	$ 10,047
Risk Grade Thirteen [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	13.00	13.00
Loans and Leases Receivable, Net of Deferred Income	$ 5,192	$ 5,480
Risk Grade Thirteen [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	13.00	13.00
Loans and Leases Receivable, Net of Deferred Income	$ 326	$ 200
Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	13.00	13.00
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 200
Risk Grade Thirteen [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade		13.00
Loans and Leases Receivable, Net of Deferred Income		$ 400

XML

Loans Loans - Age Analysis of Past Due Consumer Loans,Segregated by Class and Year of Origination (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,542,537	$ 16,336,397
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,433,625	1,410,790
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	482,148	$ 477,369
Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	47,820
Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,210
Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,393
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	37,349
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,409
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	593
Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	85,169
Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,619
Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,986
Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	16,457,368
Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,427,006
Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	475,162
Revolving Credit Facility [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	534,246
Revolving Credit Facility [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	373,610
Revolving Credit Facility [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	60
Revolving Credit Facility [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,344
Revolving Credit Facility [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,004
Revolving Credit Facility [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
Revolving Credit Facility [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,064
Revolving Credit Facility [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,344
Revolving Credit Facility [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	533,182
Revolving Credit Facility [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	371,266
Revolving Loans Converted to Term [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	10,627
Revolving Loans Converted to Term [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	26,668
Revolving Loans Converted to Term [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,431
Revolving Loans Converted to Term [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,994
Revolving Loans Converted to Term [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	250
Revolving Loans Converted to Term [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	58
Revolving Loans Converted to Term [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,681
Revolving Loans Converted to Term [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,052
Revolving Loans Converted to Term [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	8,946
Revolving Loans Converted to Term [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	24,616
2022 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	51,321
2022 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	23,162
2022 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2022 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,470
2022 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2022 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2022 [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2022 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,470
2022 [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	51,321
2022 [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	21,692
2021 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	323,117
2021 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	35,682
2021 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	303
2021 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	385
2021 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2021 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	499
2021 [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	303
2021 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	884
2021 [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	322,814
2021 [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	34,798
2020 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	225,980
2020 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	13,180
2020 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	55
2020 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	53
2020 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	4
2020 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2020 [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	59
2020 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	53
2020 [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	225,921
2020 [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	13,127
2019 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	87,129
2019 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,028
2019 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	465
2019 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	69
2019 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2019 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	23
2019 [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	465
2019 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	92
2019 [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	86,664
2019 [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,936
2018 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	49,087
2018 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,261
2018 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	309
2018 [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	54
2018 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	297
2018 [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	0
2018 [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	606
2018 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	54
2018 [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	48,481
2018 [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,207
Prior Years [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	152,118
Prior Years [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,557
Prior Years [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,587
Prior Years [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	24
Prior Years [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	854
Prior Years [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	13
Prior Years [Member] | Financial Asset, Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,441
Prior Years [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	37
Prior Years [Member] | Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	149,677
Prior Years [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 2,520

XML

Loans Loans - Revolving Loans Converted to Term (Details) - Revolving Loans Converted to Term [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	$ 14,556	$ 45,728
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	5,763	11,843
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	0	5,928
Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	47	23,303
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	3,666	0
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	858	793
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	$ 4,222	$ 3,861

XML

Loans Loans - Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 246,835	$ 248,666
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	87,026	72,091	$ 70,892	$ 73,843
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	15,422	17,217	33,472	39,553
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	128,954	144,936	144,440	134,892
Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	6,359	6,585	5,636	7,926
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	9,074	7,837	6,818	6,963
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	246,835	248,666	$ 261,258	$ 263,177
Modeled Expected Credit Losses [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	83,610	82,866
Modeled Expected Credit Losses [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	46,635	46,946
Modeled Expected Credit Losses [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,971	6,363
Modeled Expected Credit Losses [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	17,110	16,676
Modeled Expected Credit Losses [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	6,260	6,484
Modeled Expected Credit Losses [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	7,634	6,397
Q-factor adjustments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	151,197	149,348
Q-factor adjustments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	33,916	14,609
Q-factor adjustments [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	4,260	5,374
Q-factor adjustments [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	111,518	127,860
Q-factor adjustments [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	63	65
Q-factor adjustments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	1,440	1,440
Specific Valuation Allowances [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	12,028	16,452
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	6,475	10,536
Specific Valuation Allowances [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,191	5,480
Specific Valuation Allowances [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	326	400
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	36	36
Specific Valuation Allowances [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 0	$ 0

XML

Loans - Activity in the Allowance for Credit Losses on Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 248,666
Ending balance	246,835
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	72,091	$ 73,843
Credit loss, expense (reversal)	17,561	(1,965)
Charge-offs	(3,455)	(2,189)
Recoveries	829	1,203
Net charge-offs	(2,626)	(986)
Ending balance	87,026	70,892
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	17,217	39,553
Credit loss, expense (reversal)	(2,044)	(5,801)
Charge-offs	(371)	(1,433)
Recoveries	620	1,153
Net charge-offs	249	(280)
Ending balance	15,422	33,472
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	144,936	134,892
Credit loss, expense (reversal)	(15,609)	8,922
Charge-offs	(702)	0
Recoveries	329	626
Net charge-offs	(373)	626
Ending balance	128,954	144,440
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	6,585	7,926
Credit loss, expense (reversal)	(26)	(2,722)
Charge-offs	(231)	(284)
Recoveries	31	716
Net charge-offs	(200)	432
Ending balance	6,359	5,636
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	7,837	6,963
Credit loss, expense (reversal)	4,582	1,566
Charge-offs	(5,771)	(4,060)
Recoveries	2,426	2,349
Net charge-offs	(3,345)	(1,711)
Ending balance	9,074	6,818
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	248,666	263,177
Credit loss, expense (reversal)	4,464	0
Charge-offs	(10,530)	(7,966)
Recoveries	4,235	6,047
Net charge-offs	(6,295)	(1,919)
Ending balance	$ 246,835	$ 261,258

XML

Loans - Investment in Loans Related to Allowance for Loan Losses by Portfolio Segment Disaggregated Based on Impairment Methodology (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,542,537	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,584,117	5,364,954
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,036,579	1,077,792
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	207,669	428,882
Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	6,376,521	6,272,339
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,421,878	1,304,271
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,433,625	1,410,790
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	482,148	477,369
Specific Valuation Allowances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	12,028	16,452
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	6,475	10,536
Specific Valuation Allowances [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	5,191	5,480
Specific Valuation Allowances [Member] | Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	0	0
Specific Valuation Allowances [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	326	200
Specific Valuation Allowances [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	0	200
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	36	36
Specific Valuation Allowances [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	0	0
Loans Individually Evaluated for Impairment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	62,568	66,837
Loans Individually Evaluated for Impairment [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	21,529	24,523
Loans Individually Evaluated for Impairment [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	11,931	16,393
Loans Individually Evaluated for Impairment [Member] | Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	0
Loans Individually Evaluated for Impairment [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	28,806	24,670
Loans Individually Evaluated for Impairment [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	0	948
Loans Individually Evaluated for Impairment [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	302	303
Loans Individually Evaluated for Impairment [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 0

XML

Goodwill and Other Intangible Assets - Schedule of Goodwill (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 654,952	$ 654,952

XML

Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 720	$ 866
Core deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	591	718
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 129	$ 148

XML

Goodwill and Other Intangible Assets - Estimated Aggregate Future Amortization Expense for Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2022	$ 335
2023	282
2024	87
2025	11
2026	5
Thereafter	0
Future Amortization Expense, Total	$ 720	$ 866

XML

Deposits - Schedule of Deposits (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Deposit [Line Items]
Non-interest-bearing demand deposits	$ 18,114,430	$ 18,423,018
Interest-bearing Domestic Deposit, Savings	12,484,308	11,930,959
Interest-bearing Domestic Deposit, Money Market	12,490,612	11,228,815
Interest-bearing Domestic Deposit, Time Deposits	1,341,579	1,112,904
Interest-bearing deposits	26,316,499	24,272,678
Deposits	$ 44,430,929	$ 42,695,696

XML

Deposits - Additional Information About Corporation's Deposits (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Deposit Liability [Line Items]
Deposits from foreign sources (primarily Mexico)	$ 1,092,302	$ 993,479
Non-interest-bearing demand deposits	18,114,430	18,423,018
Interest-bearing deposits	26,316,499	24,272,678
Total deposits not covered by deposit insurance	25,213,248	24,125,359
Time deposits not covered by deposit insurance	357,529	238,608
Public Funds [Member]
Deposit Liability [Line Items]
Non-interest-bearing demand deposits	746,097	1,235,026
Interest-bearing deposits	$ 975,511	$ 810,863

XML

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Lessee, Operating Lease, Liability, Payments, Due	$ 8,000	$ 8,100
Significant change in expected future minimum lease payments since year end	0
Premises and Equipment
Operating Lease, Right-of-Use Asset	279,500		$ 281,400
Other Liabilities [Member]
Operating Lease, Liability	$ 311,800		$ 313,400

XML

Commitments and Contingencies - Financial Instruments with Off-Balance-Sheet Risk (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	$ 236,798	$ 238,690
Deferred Standby Letter Of Credit Fees [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	1,704	2,072
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	$ 10,356,196	$ 10,420,142

XML

Commitments and Contingencies Commitments and Contingencies - Credit Losses on Off-Balance-Sheet Commitments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Off-Balance Sheet, Credit Loss, Liability	$ 50,314	$ 44,152
Credit loss expense (benefit)	(4,464)	65
Off-Balance Sheet, Credit Loss, Liability	$ 45,850	$ 44,217

XML

Commitments and Contingencies Commitments and Contingencies - Components of Lease Commitments Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Operating Lease, Right-of-Use Asset, Amortization Expense	$ 8,105	$ 8,283
Short-term lease expense	613	204
Non-lease components (including taxes, insurance, common maintenance, etc.)	3,020	3,004
Total operating lease expense, excluding rent	$ 11,738	$ 11,491

XML

Capital and Regulatory Matters - Additional Information (Detail)			3 Months Ended		12 Months Ended
	Jan. 26, 2022 USD ($)	Nov. 19, 2020 USD ($)	Mar. 31, 2022 USD ($) quarter $ / shares shares	Mar. 31, 2021 shares	Dec. 31, 2021 USD ($) $ / shares shares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CECL Transition Amount			$ 46,200,000		$ 61,600,000
Preferred Stock, Aggregate Liquidation Preference, Value			$ 150,000,000
Treasury Stock, Shares, Acquired | shares			7,459	11,625
Maximum dividends available without prior regulatory approval			$ 325,000,000
Maximum number of quarterly periods by which the corporation has the right to defer interest payments on junior subordinated deferrable interest debentures | quarter			20
Series B Preferred Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred stock dividend rate percentage		4.45%
Preferred stock, shares issued | shares			150,000		150,000
Preferred Stock, Aggregate Liquidation Preference, Value			$ 1,000		$ 1,000
Preferred stock, par value | $ / shares			$ 0.01		$ 0.01
Preferred Stock, Liquidation Preference Per Share | $ / shares			$ 1,000
Number of Preferred Stock equivalent depositary shares | shares			40
Payments of Stock Issuance Costs		$ 4,500,000
Proceeds from Issuance of Preferred Stock and Preference Stock		$ 145,500,000
Series B Preferred Stock Equivalent Depositary Shares Member
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred Stock, Liquidation Preference Per Share | $ / shares			$ 25
Cullen/Frost [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Additional Tier 1 Capital beyond Common Equity Tier 1			$ 145,500,000		$ 145,500,000
Preferred stock dividend rate percentage			4.45%		4.45%
Cullen/Frost [Member] | Trust Preferred Securities Tier Two Capital Allowable Portion [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust preferred securities			$ 120,000,000		$ 120,000,000
Frost Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Additional Tier 1 Capital beyond Common Equity Tier 1			$ 0		0
stock repurchase 2022 plan
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock Repurchase Program, Authorized Amount	$ 100,000,000
Stock Repurchase Program, Period in Force	1 year
stock repurchase 2022 plan | Treasury Stock [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Treasury Stock, Shares, Acquired | shares			0
Subordinated Debt [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Permissible Percentage Decreased Each Of Final Five Years Of Term Of Notes			20.00%
Final years of the term of the notes			5 years
Subordinated Debt [Member] | Cullen/Frost [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Permissible portion of subordinated note included in capital			$ 80,000,000		$ 100,000,000

XML

Capital and Regulatory Matters - Actual and Required Capital Ratios (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Cullen/Frost [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 to Risk-Weighted Assets, Actual, Capital Amount	$ 3,412,080	$ 3,371,043
Common Equity Tier 1 to Risk-Weighted Assets, Actual , Ratio	12.78%	13.13%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 1,869,007	$ 1,796,549
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased In, Ratio	7.00%	7.00%
Common Equity Tier 1 to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Capital Amount	$ 1,735,506	$ 1,668,224
Common Equity Tier 1 to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 3,557,532	$ 3,516,495
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio	13.32%	13.70%
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,269,508	$ 2,181,523
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Ratio	8.50%	8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,136,007	$ 2,053,198
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	8.00%	8.00%
Total Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 3,998,333	$ 3,966,244
Total Capital to Risk-Weighted Assets, Actual, Ratio	14.97%	15.45%
Total Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,803,510	$ 2,694,823
Total Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Ratio	10.50%	10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,670,009	$ 2,566,498
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	10.00%	10.00%
Leverage Ratio, Actual, Capital Amount	$ 3,557,532	$ 3,516,495
Leverage Ratio, Actual, Ratio	7.08%	7.34%
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,010,897	$ 1,917,533
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Ratio	4.00%	4.00%
Leverage Ratio, Required to be Considered Well Capitalized, Capital Amount	$ 2,513,621	$ 2,396,917
Leverage Ratio, Required to be Considered Well Capitalized, Ratio	5.00%	5.00%
Frost Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 to Risk-Weighted Assets, Actual, Capital Amount	$ 3,301,515	$ 3,261,532
Common Equity Tier 1 to Risk-Weighted Assets, Actual , Ratio	12.39%	12.72%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 1,865,304	$ 1,795,221
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased In, Ratio	7.00%	7.00%
Common Equity Tier 1 to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Capital Amount	$ 1,732,068	$ 1,666,991
Common Equity Tier 1 to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Ratio	6.50%	6.50%
Tier 1 Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 3,301,515	$ 3,261,532
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio	12.39%	12.72%
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,265,012	$ 2,179,911
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Ratio	8.50%	8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,131,776	$ 2,051,681
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	8.00%	8.00%
Total Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 3,542,316	$ 3,491,281
Total Capital to Risk-Weighted Assets, Actual, Ratio	13.29%	13.61%
Total Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,797,956	$ 2,692,831
Total Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Ratio	10.50%	10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,664,720	$ 2,564,601
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	10.00%	10.00%
Leverage Ratio, Actual, Capital Amount	$ 3,301,515	$ 3,261,532
Leverage Ratio, Actual, Ratio	6.57%	6.80%
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,009,767	$ 1,917,679
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Ratio	4.00%	4.00%
Leverage Ratio, Required to be Considered Well Capitalized, Capital Amount	$ 2,512,209	$ 2,397,099
Leverage Ratio, Required to be Considered Well Capitalized, Ratio	5.00%	5.00%

XML

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Derivative [Line Items]
Weighted-average strike rate for outstanding interest rate caps	3.27%
Approximate credit exposure related to swaps with bank customers	$ 238,400
Cash collateral for borrowed securities deposited with other financial institutions	247,300
Interest rate swaps with upstream financial institution counterparties [Member]
Derivative [Line Items]
Approximate credit exposure related to swaps with bank customers	35,700
Not Designated as Hedging Instrument [Member] | Financial Institution Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivative [Line Items]
Estimated fair value of derivative contracts cleared through Chicago Mercantile Exchange	$ 0	$ 0

XML

Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Assets Notional Amount	$ 1,807	$ 0
Estimated Fair Value	1	0
Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Liability Notional Amount	280	2,426
Estimated Fair Value	(3)	(34)
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Assets Notional Amount	697,834	247,592
Estimated Fair Value	15,311	1,207
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Liability Notional Amount	447,742	928,756
Estimated Fair Value	(6,184)	(19,142)
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest-rate caps assets [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Assets Notional Amount	265,930	270,431
Estimated Fair Value	8,110	3,239
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Assets Notional Amount	447,742	928,756
Estimated Fair Value	10,275	39,864
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Liability Notional Amount	697,834	247,592
Estimated Fair Value	(25,437)	(2,846)
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate caps liabilities [Member]
Derivatives, Fair Value [Line Items]
Forward Contracts – Liability Notional Amount	265,930	270,431
Estimated Fair Value	$ (8,110)	$ (3,239)

XML

Derivative Financial Instruments - Schedule of Weighted-Average Rates Paid and Received for Interest Rate Swaps Outstanding (Detail)	Mar. 31, 2022
Weighted Average Interest Rate Paid [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Fair value hedge loan/lease interest rate swaps	2.11%
Weighted-Average Interest Rate Received [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Fair value hedge loan/lease interest rate swaps	0.26%
Financial Institution Counterparties [Member] | Weighted Average Interest Rate Paid [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – financial institution counterparties	3.69%
Financial Institution Counterparties [Member] | Weighted-Average Interest Rate Received [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – financial institution counterparties	2.07%
Customer Counterparties [Member] | Weighted Average Interest Rate Paid [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – customer counterparties	2.07%
Customer Counterparties [Member] | Weighted-Average Interest Rate Received [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – customer counterparties	3.69%

XML

Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Commodity Derivative Positions (Detail) bbl in Thousands, MMBTU in Thousands, $ in Thousands	Mar. 31, 2022 USD ($) bbl MMBTU	Dec. 31, 2021 USD ($) MMBTU bbl
Financial Institution Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	2,988	4,809
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	9,767	7,032
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 9,735	$ 14,721
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (189,416)	$ (73,594)
Financial Institution Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	14,564	15,947
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	27,474	29,446
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 1,813	$ 4,143
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (50,244)	$ (21,249)
Customer Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	9,767	7,046
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	2,988	4,796
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 190,776	$ 74,437
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (9,710)	$ (14,294)
Customer Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	27,474	29,446
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	14,564	15,947
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 50,423	$ 21,456
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (1,811)	$ (4,124)

XML

Derivative Financial Instruments - Schedule of Notional Amounts and Fair Values of Open Foreign Currency Forward Contracts (Details) € in Thousands, $ in Thousands, $ in Thousands	Mar. 31, 2022 USD ($)	Mar. 31, 2022 EUR (€)	Mar. 31, 2022 CAD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2021 EUR (€)	Dec. 31, 2021 CAD ($)
Financial Institution Counterparties [Member] | GBP Foreign Exchange Forward
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	$ 18			$ 29
Forward Contracts - Liability Estimated Fair Value	(111)			0
Financial Institution Counterparties [Member] | Foreign Exchange Forward [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	0			0
Forward Contracts - Liability Estimated Fair Value	(6)			0
Financial Institution Counterparties [Member] | Other Assets [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Notional Amount		€ 2,400	$ 0		€ 1,900	$ 658
Financial Institution Counterparties [Member] | Other Liabilities [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Liability Notional Amount		6,500	658		0	0
Customer Counterparties [Member] | GBP Foreign Exchange Forward
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	122			0
Forward Contracts - Liability Estimated Fair Value	(14)			(55)
Customer Counterparties [Member] | Foreign Exchange Forward [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	$ 10			$ 4
Customer Counterparties [Member] | Other Assets [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Notional Amount		6,500	$ 658		0	$ 658
Customer Counterparties [Member] | Other Liabilities [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Liability Notional Amount | €		€ 2,400			€ 1,900

XML

Derivative Financial Instruments - Schedule of Amounts Related to Interest Rate Derivatives Designated as Hedges of Fair Value (Detail) - Designated as Hedging Instrument [Member] - Commercial Loan/Lease Interest Rate Swaps [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Interest Income on Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) included in income	$ (13)	$ (28)
Other Non-Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) included in income	$ 2	$ (3)

XML

Derivative Financial Instruments - Schedule of Amounts Related to Non-Hedging Interest Rate and Commodity Derivatives (Detail) - Non Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Interest Rate Contract [Member] | Other Non-Interest Income [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	$ 516	$ 1,587
Interest Rate Contract [Member] | Other Non-Interest Expense [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	0	(1)
Commodity Contract [Member] | Other Non-Interest Income [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	929	1,154
Foreign Currency Derivative Contracts [Member] | Other Non-Interest Income [Member]
Other Non Interest Income Non Hedging Interest Rate Derivatives [Line Items]
Amount of gain (loss) included in income (expense)	$ 18	$ 30

XML

Balance Sheet Offsetting - Financial Instruments Eligible for Offset Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	$ 34,988	$ 23,339
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	34,988	23,339
Gross Amount Recognized, Resell agreements, Financial assets	0	7,903
Gross Amount Offset, Resell agreements, Financial assets	0	0
Net Amount Recognized, Resell agreements, Financial assets	0	7,903
Gross Amount Recognized, Financial assets	34,988	31,242
Gross Amount Offset, Financial assets	0	0
Net Amount Recognized, Financial assets	34,988	31,242
Gross Amount Recognized, Derivatives, Financial Liabilities	245,964	114,019
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	245,964	114,019
Gross Amount Recognized, Repurchase agreements, Financial liabilities	1,842,618	2,740,799
Gross Amount Offset, Repurchase agreements, Financial liabilities	0	0
Net Amount Recognized, Repurchase agreements, Financial liabilities	1,842,618	2,740,799
Gross Amount Recognized, Financial liabilities	2,088,582	2,854,818
Gross Amount Offset, Financial liabilities	0	0
Net Amount Recognized, Financial Liabilities	2,088,582	2,854,818
Loan/lease interest rate swaps and caps [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	23,422	4,446
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	23,422	4,446
Loan/lease interest rate swaps [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Liabilities	6,187	19,176
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	6,187	19,176
Commodity swaps and options [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	11,548	18,864
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	11,548	18,864
Gross Amount Recognized, Derivatives, Financial Liabilities	239,660	94,843
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	239,660	$ 94,843
Foreign currency forward contracts [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	18
Gross Amount Offset, Derivatives, Financial assets	0
Net Amount Recognized, Derivatives, Financial assets	18
Gross Amount Recognized, Derivatives, Financial Liabilities	117
Gross Amount Offset, Derivatives, Financial liabilities	0
Net Amount Recognized, Derivatives, Financial liabilities	$ 117

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Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 34,988	$ 23,339
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(28,281)	(23,339)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(6,707)	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Resell agreements, Financial Assets	0	7,903
Gross Amounts Not Offset Financial Instruments, Resell Agreements	0	0
Gross Amounts Not Offset Collateral, Resell Agreements, Financial Assets	0	(7,903)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	34,988	31,242
Gross Amounts Not Offset Collateral, Financial Assets	(6,707)	(7,903)
Net Amount, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	245,964	114,019
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(28,281)	(23,339)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(217,683)	(90,573)
Net Amount, Derivatives, Financial Liabilities	0	107
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	1,842,618	2,740,799
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(1,842,618)	(2,740,799)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Financial Liabilities	2,088,582	2,854,818
Gross Amounts Not Offset Collateral, Financial Liabilities	(2,060,301)	(2,831,372)
Net Amount, Financial Liabilities	0	107
Counterparty A [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	32	6
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(32)	(6)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	2,635	3,870
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(32)	(6)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(2,603)	(3,864)
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty B [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	11,998	7,655
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(11,998)	(7,655)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	46,953	28,130
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(11,998)	(7,655)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(34,955)	(20,475)
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty C [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Liabilities	3	9
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(3)	(9)
Net Amount, Derivatives, Financial Liabilities	0	0
Other Counterparties [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	22,958	15,678
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(16,251)	(15,678)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(6,707)	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	196,373	82,010
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(16,251)	(15,678)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(180,122)	(66,225)
Net Amount, Derivatives, Financial Liabilities	$ 0	$ 107

XML

Balance Sheet Offsetting Balance Sheet Offsetting - Remaining Contractual Maturity of the Securities Sold Under Agreement to Repurchase (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Remaining Contractual Maturity of the Securities Sold Under Agreement to Repurchase [Line Items]
Remaining contractual maturity of the agreements overnight and continuous	$ 1,842,618	$ 2,740,799
Remaining contractual maturity of the agreements up to 30 Days	0	0
Remaining contractual maturity of the agreements 30 to 90 Days	0	0
Remaining contractual maturity of the agreements greater than 90 Days	0	0
Remaining contractual maturity of the agreements total	1,842,618	2,740,799
Securities Sold under Agreements to Repurchase, Gross	1,842,618	2,740,799
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	0	0
US Treasury Securities [Member]
Remaining Contractual Maturity of the Securities Sold Under Agreement to Repurchase [Line Items]
Remaining contractual maturity of the agreements overnight and continuous	876,879	1,342,591
Remaining contractual maturity of the agreements up to 30 Days	0	0
Remaining contractual maturity of the agreements 30 to 90 Days	0	0
Remaining contractual maturity of the agreements greater than 90 Days	0	0
Remaining contractual maturity of the agreements total	876,879	1,342,591
Residential Mortgage Backed Securities [Member]
Remaining Contractual Maturity of the Securities Sold Under Agreement to Repurchase [Line Items]
Remaining contractual maturity of the agreements overnight and continuous	965,739	1,398,208
Remaining contractual maturity of the agreements up to 30 Days	0	0
Remaining contractual maturity of the agreements 30 to 90 Days	0	0
Remaining contractual maturity of the agreements greater than 90 Days	0	0
Remaining contractual maturity of the agreements total	$ 965,739	$ 1,398,208

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Stock-Based Compensation Stock-Based Compensation - Narrative (Details)	Mar. 31, 2022 shares
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	794,493

XML

Stock-Based Compensation - Summary of Activity in Corporation's Active Stock Plans (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised, Number of Shares	(115,430)	(513,824)
Director deferred stock units outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares/Units	56,301
Ending Balance, Number of Shares/Units	56,301
Beginning Balance, Weighted-Average Grant-Date Fair Value	$ 79.21
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 79.21
Non-Vested Stock Awards/Stock Units Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares/Units	449,337
Granted, Number of Units	1,038
Forfeited/expired, Number of Shares/Units	(1,786)
Ending Balance, Number of Shares/Units	448,589
Beginning Balance, Weighted-Average Grant-Date Fair Value	$ 93.05
Granted Weighted-Average Grant-Date Fair Value	145.32
Forfeited/Expired, Weighted-Average Price	89.50
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 93.19
Stock Options Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares	877,681
Stock options exercised, Number of Shares	(90,250)
Ending Balance, Number of Shares	787,431
Beginning Balance, Weighted-Average Exercise Price	$ 69.02
Stock options exercised, Weighted-Average Exercise Price	63.59
Ending Balance, Weighted-Average Exercise Price	$ 69.64
Maximum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares/Units	202,460
Stock Awards exercised/vested, Number of Shares	(25,180)
Forfeited/expired, Number of Shares/Units	(16,058)
Ending Balance, Number of Shares/Units	161,222
Beginning Balance, Weighted-Average Grant-Date Fair Value	$ 84.71
Stock Award Exercised/Vested, Weighted Average Grant Date Fair Value	87.18
Forfeited/Expired, Weighted-Average Price	87.18
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 84.08

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Stock-Based Compensation - Shares Issued in Connection with Stock Compensation Awards (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
New shares issued from available authorized shares	0	0
Shares issued from available treasury stock	115,430	513,824
Proceeds from stock option exercises	$ 5,739	$ 29,397

XML

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock units	$ 2,358	$ 1,883
Share-based compensation benefit on performance stock units	(246)
Share-based compensation expense on performance stock units		643
Total	2,112	2,526
Income tax benefit	$ 708	$ 367

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Stock-Based Compensation - Unrecognized Stock-Based Compensation Expense (Detail) $ in Thousands	Mar. 31, 2022 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock units	$ 16,063
Performance stock units	8,664
Total	$ 24,727

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Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings Per Share [Abstract]
Net income	$ 99,102	$ 116,015
Less: Preferred stock dividends	1,669	2,151
Net income available to common shareholders	97,433	113,864
Less: Earnings allocated to participating securities	849	1,162
Distributed earnings allocated to common stock	48,051	45,660
Undistributed earnings allocated to common stock	48,533	67,042
Net earnings allocated to common stock	$ 96,584	$ 112,702
Weighted-average shares outstanding for basic earnings per common share	64,051,202	63,306,493
Dilutive effect of stock compensation	409,705	509,290
Weighted-average shares outstanding for diluted earnings per common share	64,460,907	63,815,783

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Defined Benefit Plans Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($)
Retirement Benefits [Abstract]
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 0
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year	$ 0

XML

Defined Benefit Plans - Net Periodic Cost (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Retirement Benefits [Abstract]
Expected return on plan assets, net of expenses	$ (3,491)	$ (3,210)
Interest cost on projected benefit obligation	1,004	835
Net amortization and deferral	741	1,529
Net periodic expense (benefit)	$ (1,746)	$ (846)

XML

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	$ 110.3
Deferred Tax Liabilities, Net			$ 81.2
Valuation allowance	$ 0.0
U.S. federal statutory income tax rate, percent	21.00%	21.00%
Unrecognized tax benefits	$ 0.0	$ 0.0

XML

Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 13,059	$ 3,725
Deferred income tax expense (benefit)	(432)	4,172
Income tax expense, as reported	$ 12,627	$ 7,897
Effective tax rate	11.30%	6.40%

XML

Other Comprehensive Income (Loss) - Component of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Equity [Abstract]
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Before Tax Amount	$ (910,795)	$ (159,779)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Before Tax Amount	(209)	(259)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Before Tax Amount	0	0
Total securities available for sale and transferred securities, before tax amount	(911,004)	(160,038)
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit), before tax amount	741	1,529
Total defined-benefit post-retirement benefit plans	741	1,529
Total other comprehensive income (loss), before tax	(910,263)	(158,509)
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Tax Expense (Benefit)	(191,267)	(33,554)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Tax Expense (Benefit)	(44)	(54)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Tax Expense (Benefit)	0	0
Total securities available for sale and transferred securities, Tax Expense (Benefit)	(191,311)	(33,608)
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit), Tax Expense (Benefit)	156	321
Total defined-benefit post-retirement benefit plans, Tax Expense (Benefit)	156	321
Total other comprehensive income (loss), Tax Expense (Benefit)	(191,155)	(33,287)
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Net of Tax	(719,528)	(126,225)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Net of Tax	(165)	(205)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Net of Tax	0	0
Total securities available for sale and transferred securities, Net of Tax	(719,693)	(126,430)
Reclassification adjustment for net amortization of actuarial gain/lloss included in net income as a component of net periodic cost (benefit), Net of Tax	585	1,208
Total defined-benefit post-retirement benefit plans, Net of Tax Amount	585	1,208
Other comprehensive income (loss), net of tax	$ (719,108)	$ (125,222)

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Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 347,318
Other comprehensive income (loss), net of tax	(719,108)	$ (125,222)
Ending Balance	(371,790)
Securities Available For Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	380,209	563,801
Other comprehensive income (loss) before reclassifications	(719,693)	(126,430)
Reclassification of amounts included in net income	0	0
Other comprehensive income (loss), net of tax	(719,693)	(126,430)
Ending Balance	(339,484)	437,371
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(32,891)	(50,831)
Other comprehensive income (loss) before reclassifications	0	0
Reclassification of amounts included in net income	585	1,208
Other comprehensive income (loss), net of tax	585	1,208
Ending Balance	(32,306)	(49,623)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	347,318	512,970
Other comprehensive income (loss) before reclassifications	(719,693)	(126,430)
Reclassification of amounts included in net income	585	1,208
Other comprehensive income (loss), net of tax	(719,108)	(125,222)
Ending Balance	$ (371,790)	$ 387,748

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Operating Segments - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2022 Segment
Segment Reporting [Abstract]
Number of primary operating segments	2

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Operating Segments - Summary of Operating Results by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	$ 249,071	$ 240,881
Credit loss expense	0	63
Total non-interest income	101,390	93,236
Total non-interest expense	238,732	210,142
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	111,729	123,912
Income taxes	12,627	7,897
Net income	99,102	116,015
Less: Preferred stock dividends	1,669	2,151
Net Income (Loss) Available to Common Stockholders, Basic	97,433	113,864
Revenues from (expenses to) external customers	350,461	334,117
Bank
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	250,119	242,205
Credit loss expense	(1)	63
Total non-interest income	58,706	53,780
Total non-interest expense	206,538	179,151
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	102,288	116,771
Income taxes	11,014	7,177
Net income	91,274	109,594
Less: Preferred stock dividends	0	0
Net Income (Loss) Available to Common Stockholders, Basic	91,274	109,594
Revenues from (expenses to) external customers	308,825	295,985
Frost Wealth Advisors [Member]
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	700	486
Credit loss expense	1	0
Total non-interest income	43,229	39,609
Total non-interest expense	30,910	29,937
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	13,018	10,158
Income taxes	2,734	2,133
Net income	10,284	8,025
Less: Preferred stock dividends	0	0
Net Income (Loss) Available to Common Stockholders, Basic	10,284	8,025
Revenues from (expenses to) external customers	43,929	40,095
Non-Banks [Member]
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	(1,748)	(1,810)
Credit loss expense	0	0
Total non-interest income	(545)	(153)
Total non-interest expense	1,284	1,054
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(3,577)	(3,017)
Income taxes	(1,121)	(1,413)
Net income	(2,456)	(1,604)
Less: Preferred stock dividends	1,669	2,151
Net Income (Loss) Available to Common Stockholders, Basic	(4,125)	(3,755)
Revenues from (expenses to) external customers	$ (2,293)	$ (1,963)

XML

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments using fair value measurement option	$ 0	$ 0

XML

Fair Value Measurements - Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	$ 16,184,539	$ 13,924,628
Trading account securities	29,518	25,162
Derivative assets	34,988	23,339
Derivative liabilities	245,964	114,019
Interest rate swaps, caps and floors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	33,697	44,310
Derivative liabilities	39,734	25,261
Commodity swaps and options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	252,747	114,757
Derivative liabilities	251,181	113,261
Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	150	33
Derivative liabilities	131	55
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	3,507,746	2,179,433
Trading account securities	23,939	24,237
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	5,376,039	4,066,265
States and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	7,258,393	7,636,571
Trading account securities	5,579	925
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	42,361	42,359
Level 1 [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	150	33
Derivative liabilities	131	55
Level 1 [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	3,507,746	2,179,433
Trading account securities	23,939	24,237
Level 2 [Member] | Interest rate swaps, caps and floors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	33,697	44,310
Derivative liabilities	39,734	25,261
Level 2 [Member] | Commodity swaps and options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	252,747	114,757
Derivative liabilities	251,181	113,261
Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	5,376,039	4,066,265
Level 2 [Member] | States and political subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	7,258,393	7,636,571
Trading account securities	5,579	925
Level 2 [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	$ 42,361	$ 42,359

XML

Fair Value Measurements - Impaired Loans Remeasured and Reported at Fair Value of Underlying Collateral (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2021
Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Carrying value of impaired loans before allocations	$ 2,064	$ 100
Impaired Financing Receivable, Related Allowance	(126)	0
Loans receivable, fair value disclosure	1,938	100
Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Carrying value of impaired loans before allocations	5,711	15,013
Impaired Financing Receivable, Reversal of Specific Valuation Allowance Allocations	3,965	600
Loans receivable, fair value disclosure	$ 9,676	$ 15,613

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Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity	$ 1,665,465	$ 1,749,179
Loans, net	16,295,702	16,087,731
Deposits	44,430,929	42,695,696
Federal funds purchased	35,200	25,925
Repurchase agreements	1,842,618	2,740,799
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,026	123,011
Subordinated notes	99,217	99,178
Carrying Amount [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	14,457,083	16,583,000
Securities held to maturity	1,665,465	1,749,179
Cash surrender value of life insurance policies	189,471	190,139
Accrued interest receivable	131,370	179,111
Deposits	44,430,929	42,695,696
Federal funds purchased	35,200	25,925
Repurchase agreements	1,842,618	2,740,799
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,026	123,011
Subordinated notes	99,217	99,178
Accrued interest payable	2,147	3,026
Carrying Amount [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	16,295,702	16,087,731
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	14,457,083	16,583,000
Securities held to maturity	1,639,993	1,809,143
Cash surrender value of life insurance policies	189,471	190,139
Accrued interest receivable	131,370	179,111
Deposits	44,422,700	41,343,426
Federal funds purchased	35,200	25,925
Repurchase agreements	1,842,618	2,740,799
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,712	123,712
Subordinated notes	105,740	111,430
Accrued interest payable	2,147	3,026
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 16,053,955	$ 16,079,454