Cullen/Frost Bankers (CFR) 10-Q 27 Oct 22 2022 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	9 Months Ended
	Sep. 30, 2022	Oct. 24, 2022	Dec. 31, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 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		64,298,720
Common stock, par value	$ 0.01		$ 0.01
Amendment Flag	false
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
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

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets:
Cash and due from banks	$ 665,123	$ 555,778
Interest-bearing deposits	12,863,775	15,985,244
Federal funds sold	91,650	34,075
Resell agreements	12,150	7,903
Total cash and cash equivalents	13,632,698	16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Securities available for sale, at estimated fair value	17,399,107	13,924,628
Trading account securities	25,008	25,162
Loans, net of unearned discounts	16,950,629	16,336,397
Less: Allowance for credit losses on loans	(234,315)	(248,666)
Net loans	16,716,314	16,087,731
Premises and equipment, net	1,068,749	1,050,331
Goodwill	654,952	654,952
Other intangible assets, net	486	866
Cash surrender value of life insurance policies	190,368	190,139
Accrued interest receivable and other assets	1,083,803	612,502
Total assets	52,945,569	50,878,490
Liabilities:
Non-interest-bearing demand deposits	18,565,820	18,423,018
Interest-bearing deposits	27,994,366	24,272,678
Total deposits	46,560,186	42,695,696
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior Subordinated Notes	123,055	123,011
Subordinated notes, net of unamortized issuance costs	99,295	99,178
Accrued interest payable and other liabilities	1,241,622	754,326
Total liabilities	50,133,097	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 September 30, 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 September 30, 2022 and December 31, 2021	642	642
Additional paid-in capital	1,018,624	1,009,921
Retained earnings	3,179,964	2,956,966
Accumulated other comprehensive income (loss), net of tax	(1,528,925)	347,318
Treasury stock, at cost; 24,917 shares at September 30, 2022 and 250,070 shares at December 31, 2021	(3,285)	(20,744)
Total shareholders’ equity	2,812,472	4,439,555
Total liabilities and shareholders’ equity	$ 52,945,569	$ 50,878,490

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Securities, held-to-maturity, allowance for credit loss	$ 158	$ 158
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	24,917	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

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Interest income:
Loans, including fees	$ 205,932	$ 168,779	$ 522,588	$ 518,957
Securities:
Taxable	68,311	20,736	167,734	61,366
Tax-exempt	59,450	56,882	173,394	169,656
Interest-bearing deposits	74,257	5,830	106,971	11,877
Federal funds sold	316	2	428	13
Resell agreements	64	6	78	11
Total interest income	408,330	252,235	971,193	761,880
Interest expense:
Deposits	42,682	3,677	62,187	10,693
Federal funds purchased	249	9	336	24
Repurchase agreements	7,529	632	9,837	1,597
Junior subordinated deferrable interest debentures	1,159	631	2,515	1,915
Subordinated notes	1,164	1,164	3,492	3,492
Total interest expense	52,783	6,113	78,367	17,721
Net interest income	355,547	246,122	892,826	744,159
Credit loss expense	0	0	0	63
Net interest income after credit loss expense	355,547	246,122	892,826	744,096
Non-interest income:
Trust and investment management fees	38,552	37,381	114,984	110,569
Service charges on deposit accounts	22,960	21,216	69,570	61,058
Insurance commissions and fees	13,152	11,748	41,536	39,834
Interchange and card transaction fees	4,614	4,490	13,751	13,224
Other charges, commissions and fees	11,095	9,785	30,609	26,729
Net gain (loss) on securities transactions	0	0	0	0
Other	9,448	8,569	28,688	26,258
Total non-interest income	99,821	93,189	299,138	277,672
Non-interest expense:
Salaries and wages	127,189	99,463	355,399	289,956
Employee benefits	21,680	21,576	66,633	62,840
Net occupancy	28,133	27,208	83,923	79,909
Technology, furniture and equipment	30,781	28,494	89,859	84,508
Deposit insurance	4,279	3,088	11,636	8,893
Intangible amortization	103	157	380	544
Other	45,733	38,017	135,147	116,749
Total non-interest expense	257,898	218,003	742,977	643,399
Income before income taxes	197,470	121,308	448,987	378,369
Income taxes	27,710	13,333	61,011	36,311
Net income	169,760	107,975	387,976	342,058
Preferred stock dividends	1,668	1,668	5,006	5,488
Net income available to common shareholders	$ 168,092	$ 106,307	$ 382,970	$ 336,570
Earnings per common share:
Basic	$ 2.60	$ 1.66	$ 5.92	$ 5.25
Diluted	$ 2.59	$ 1.65	$ 5.90	$ 5.22

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Net income	$ 169,760	$ 107,975	$ 387,976	$ 342,058
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	(829,324)	(80,668)	(2,376,642)	(209,779)
Change in net unrealized gain on securities transferred to held to maturity	(174)	(237)	(572)	(741)
Reclassification adjustment for net (gains) losses included in net income	0	0	0	0
Total securities available for sale and transferred securities, before tax amount	(829,498)	(80,905)	(2,377,214)	(210,520)
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	2,223	4,587
Total defined-benefit post-retirement benefit plans	741	1,529	2,223	4,587
Other comprehensive income (loss), before tax	(828,757)	(79,376)	(2,374,991)	(205,933)
Deferred tax expense (benefit)	(174,038)	(16,669)	(498,748)	(43,246)
Other comprehensive income (loss), net of tax	(654,719)	(62,707)	(1,876,243)	(162,687)
Comprehensive income (loss)	$ (484,959)	$ 45,268	$ (1,488,267)	$ 179,371

Consolidated Statements of Chan

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	342,058				342,058
Other comprehensive income (loss)	(162,687)					(162,687)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	37,810				(26,652)		64,462
Stock compensation expense recognized in earnings	7,756			7,756
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 shares YTD in 2021)	(1,342)						(1,342)
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 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(5,488)				(5,488)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(140,510)				(140,510)
Total shareholders’ equity at end of period at Sep. 30, 2021	4,372,362	145,452	642	1,004,924	2,920,074	350,283	(49,013)
Total shareholders’ equity at beginning of period at Jun. 30, 2021	4,373,817	145,452	642	1,002,939	2,862,966	412,990	(51,172)
Net income	107,975				107,975
Other comprehensive income (loss)	(62,707)					(62,707)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	1,128				(1,085)		2,213
Stock compensation expense recognized in earnings	1,985			1,985
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 shares YTD in 2021)	(54)						(54)
Cash dividends – preferred stock (approximately $11.13 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(1,668)				(1,668)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(48,114)				(48,114)
Total shareholders’ equity at end of period at Sep. 30, 2021	4,372,362	145,452	642	1,004,924	2,920,074	350,283	(49,013)
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	387,976				387,976
Other comprehensive income (loss)	(1,876,243)					(1,876,243)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	11,760				(6,695)		18,455
Stock compensation expense recognized in earnings	8,703			8,703
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 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 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(5,006)				(5,006)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(153,277)				(153,277)
Total shareholders’ equity at end of period at Sep. 30, 2022	2,812,472	145,452	642	1,018,624	3,179,964	(1,528,925)	(3,285)
Total shareholders’ equity at beginning of period at Jun. 30, 2022	3,346,975	145,452	642	1,015,451	3,070,109	(874,206)	(10,473)
Net income	169,760				169,760
Other comprehensive income (loss)	(654,719)					(654,719)
Stock option exercises/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD in 2021)	5,270				(1,918)		7,188
Stock compensation expense recognized in earnings	3,173			3,173
Cash dividends – preferred stock (approximately $11.13 and $33.38 per share which is equivalent to approximately $0.28 and $0.83 per depository share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share which is equivalent to approximately $0.28 and $0.91 per depository share QTD and YTD in 2021, respectively)	(1,668)				(1,668)
Cash dividends – common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	(56,319)				(56,319)
Total shareholders’ equity at end of period at Sep. 30, 2022	$ 2,812,472	$ 145,452	$ 642	$ 1,018,624	$ 3,179,964	$ (1,528,925)	$ (3,285)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Stockholders' Equity [Abstract]
Stock option exercise/stock unit conversions (88,350 shares QTD and 232,612 shares YTD in 2022 and 21,968 shares QTD and 650,044 shares YTD during 2021)	88,350	21,968	232,612	650,044
Purchase of treasury stock (7,459 shares YTD in 2022 and 478 shares QTD and 12,103 shares YTD in 2021)		478	7,459	12,103
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 and $33.38 per share QTD and YTD in 2022, respectively and $11.13 and $36.59 per share QTD and YTD during 2021, respectively)	$ 11.13	$ 11.13	$ 33.38	$ 36.59
Cash dividend - Preferred Stock Dividends equivalent Per depositary Share Declared ($0.28 and $0.83 QTD and YTD respectively, during 2022 and $0.28 and 0.91 QTD and YTD, respectively during 2021)	0.28	0.28	0.83	0.91
Cash dividends - common stock ($0.87 per share QTD and $2.37 per share YTD in 2022 and $0.75 per share QTD and $2.19 per share YTD in 2021)	$ 0.87	$ 0.75	$ 2.37	$ 2.19

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Operating Activities:
Net income	$ 387,976	$ 342,058
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	0	63
Deferred tax expense (benefit)	(3,378)	4,672
Accretion of loan discounts	(10,572)	(9,879)
Securities premium amortization (discount accretion), net	76,328	90,017
Net (gain) loss on securities transactions	0	0
Depreciation and amortization	53,303	51,550
Net (gain) loss on sale/write-down of assets/foreclosed assets	109	(1,885)
Stock-based compensation	8,703	7,756
Net tax benefit from stock-based compensation	2,894	4,505
Earnings on life insurance policies	(1,561)	(1,901)
Net change in:
Trading account securities	154	(421)
Lease right-of-use assets	18,151	17,566
Accrued interest receivable and other assets	(63,382)	(65,849)
Accrued interest payable and other liabilities	71,187	114,361
Net cash from operating activities	539,912	552,613
Investing Activities:
Securities held-to-maturity - Purchases	(878,434)	0
Securities held to maturity: Maturities, calls and principal repayments	557,901	171,969
Securities available for sale:
Purchases	(6,702,519)	(4,105,085)
Sales	0	0
Maturities, calls and principal repayments	1,140,939	3,125,786
Proceeds from sale of loans	2,365	0
Net change in loans	(617,981)	1,649,429
Benefits received on life insurance policies	1,332	1,944
Proceeds from sales of premises and equipment	47	7,033
Purchases of premises and equipment	(55,635)	(37,088)
Proceeds from sales of repossessed properties	2,585	809
Net cash from investing activities	(6,549,400)	814,797
Financing Activities:
Net change in deposits	3,864,490	4,597,006
Net change in short-term borrowings	(657,785)	110,232
Proceeds from stock option exercises	11,760	37,810
Purchase of treasury stock	(996)	(1,342)
Cash dividends paid on preferred stock	(5,006)	(5,488)
Cash dividends paid on common stock	(153,277)	(140,510)
Net cash from financing activities	3,059,186	4,597,708
Net change in cash and cash equivalents	(2,950,302)	5,965,118
Cash and cash equivalents at beginning of period	16,583,000	10,288,853
Cash and cash equivalents at end of period	$ 13,632,698	$ 16,253,971

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 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: Nine Months Ended 2022 2021 Cash paid for interest $ 71,848 $ 23,722 Cash paid for income taxes 78,500 28,043 Significant non-cash transactions: Unsettled securities transactions 470,813 600,874 Loans foreclosed and transferred to other real estate owned and foreclosed assets — 3,464 Right-of-use lease assets obtained in exchange for lessee operating lease liabilities 23,959 4,045 Treasury stock issued to 401(k) stock purchase plan — 1,749

Securities

Securities	9 Months Ended
	Sep. 30, 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 September 30, 2022 and December 31, 2021 is presented below. Amortized Gross Gross Estimated Allowance Net September 30, 2022 Residential mortgage-backed securities $ 526,397 $ — $ 68,024 $ 458,373 $ — $ 526,397 States and political subdivisions 1,646,345 90 188,964 1,457,471 (158) 1,646,187 Other 1,500 — 57 1,443 — 1,500 Total $ 2,174,242 $ 90 $ 257,045 $ 1,917,287 $ (158) $ 2,174,084 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 $271.6 million and $642.3 million at September 30, 2022 and December 31, 2021, respectively. Accrued interest receivable on held-to-maturity securities totaled $11.5 million and $18.4 million at September 30, 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 $2.0 million ($1.6 million, net of tax) at September 30, 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 September 30, 2022 and December 31, 2021: States and Political Subdivisions Not Guaranteed or Pre-Refunded Guaranteed by the Texas PSF Pre-Refunded Total Other September 30, 2022 Aaa/AAA $ 220,180 $ 1,116,482 $ 121,042 $ 1,457,704 $ — Aa/AA 188,641 — — 188,641 — Not rated — — — — 1,500 Total $ 408,821 $ 1,116,482 $ 121,042 $ 1,646,345 $ 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 and nine months ended September 30, 2022 and 2021. Three Months Ended Nine Months Ended 2022 2021 2022 2021 Beginning balance $ 158 $ 158 $ 158 $ 160 Credit loss expense (benefit) — — — (2) Ending balance $ 158 $ 158 $ 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 September 30, 2022 and December 31, 2021 is presented below. Amortized Gross Gross Allowance Estimated September 30, 2022 U.S. Treasury $ 5,447,478 $ — $ 424,861 $ — $ 5,022,617 Residential mortgage-backed securities 6,685,418 1,293 987,902 — 5,698,809 States and political subdivisions 7,121,730 1,395 487,827 — 6,635,298 Other 42,383 — — — 42,383 Total $ 19,297,009 $ 2,688 $ 1,900,590 $ — $ 17,399,107 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 September 30, 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 75.1% 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 $4.9 billion and $5.8 billion at September 30, 2022 and December 31, 2021, respectively. Accrued interest receivable on available-for-sale securities totaled $99.7 million and $120.5 million at September 30, 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 September 30, 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 Unrealized Estimated Unrealized Estimated Unrealized U.S. Treasury $ 4,429,609 $ 323,346 $ 593,008 $ 101,515 $ 5,022,617 $ 424,861 Residential mortgage-backed securities 4,280,074 713,685 1,032,311 274,217 5,312,385 987,902 States and political subdivisions 5,943,551 412,938 194,456 74,889 6,138,007 487,827 Total $ 14,653,234 $ 1,449,969 $ 1,819,775 $ 450,621 $ 16,473,009 $ 1,900,590 As of September 30, 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 September 30, 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 $ — $ — $ 514,321 $ 12,076 $ 526,397 States and political subdivisions 121,042 29,534 9,880 1,485,889 1,646,345 Other — 1,500 — — 1,500 Total $ 121,042 $ 31,034 $ 524,201 $ 1,497,965 $ 2,174,242 Estimated Fair Value Residential mortgage-backed securities $ — $ — $ 448,514 $ 9,859 $ 458,373 States and political subdivisions 120,786 29,362 9,850 1,297,473 1,457,471 Other — 1,443 — — 1,443 Total $ 120,786 $ 30,805 $ 458,364 $ 1,307,332 $ 1,917,287 Available For Sale Amortized Cost U. S. Treasury $ — $ 3,821,606 $ 1,433,912 $ 191,960 $ 5,447,478 Residential mortgage-backed securities 28 9,355 17,253 6,658,782 6,685,418 States and political subdivisions 250,317 1,470,384 944,279 4,456,750 7,121,730 Other — — — — 42,383 Total $ 250,345 $ 5,301,345 $ 2,395,444 $ 11,307,492 $ 19,297,009 Estimated Fair Value U. S. Treasury $ — $ 3,648,015 $ 1,232,969 $ 141,633 $ 5,022,617 Residential mortgage-backed securities 27 9,130 17,167 5,672,485 5,698,809 States and political subdivisions 250,875 1,462,732 894,174 4,027,517 6,635,298 Other — — — — 42,383 Total $ 250,902 $ 5,119,877 $ 2,144,310 $ 9,841,635 $ 17,399,107 Sales of Securities. No held to maturity or available for sale securities were sold during the three or nine months ended September 30, 2022 or 2021. Premiums and Discounts . Premium amortization and discount accretion included in interest income on securities was as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Premium amortization $ (27,165) $ (30,240) $ (84,278) $ (92,016) Discount accretion 4,062 657 7,950 1,999 Net (premium amortization) discount accretion $ (23,103) $ (29,583) $ (76,328) $ (90,017) Trading Account Securities. Trading account securities, at estimated fair value, were as follows: September 30, December 31, U.S. Treasury $ 25,008 $ 24,237 States and political subdivisions — 925 Total $ 25,008 $ 25,162 Net gains and losses on trading account securities were as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Net gain on sales transactions $ 1,110 $ 314 $ 2,462 $ 716 Net mark-to-market gains (losses) 9 (2) (235) (71) Net gain (loss) on trading account securities $ 1,119 $ 312 $ 2,227 $ 645

Loans

Loans	9 Months Ended
	Sep. 30, 2022
Receivables [Abstract]
Loans	Loans Loans were as follows: September 30, December 31, Commercial and industrial $ 5,531,820 $ 5,364,954 Energy: Production 701,975 878,436 Service 127,065 105,901 Other 89,085 93,455 Total energy 918,125 1,077,792 Paycheck Protection Program 51,048 428,882 Commercial real estate: Commercial mortgages 6,149,504 5,867,062 Construction 1,557,415 1,304,271 Land 524,423 405,277 Total commercial real estate 8,231,342 7,576,610 Consumer real estate: Home equity loans 401,234 324,157 Home equity lines of credit 661,618 519,098 Other 652,884 567,535 Total consumer real estate 1,715,736 1,410,790 Total real estate 9,947,078 8,987,400 Consumer and other 502,558 477,369 Total loans $ 16,950,629 $ 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 September 30, 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 5.4% of total loans (also 5.4% excluding PPP loans). Unfunded commitments to extend credit and standby letters of credit issued to customers in the energy industry totaled $1.1 billion and $117.0 million, respectively, as of September 30, 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 September 30, 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 $356.4 million at September 30, 2022 and $350.5 million at December 31, 2021. Accrued Interest Receivable. Accrued interest receivable on loans totaled $48.7 million and $40.0 million at September 30, 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: September 30, 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 $ 7,267 $ 4,425 $ 22,582 $ 4,701 Energy 16,134 7,277 14,433 8,533 Paycheck Protection Program — — — — Commercial real estate: Buildings, land and other 5,489 2,497 15,297 13,817 Construction — — 948 — Consumer real estate 1,014 712 440 138 Consumer and other — — 13 13 Total $ 29,904 $ 14,911 $ 53,713 $ 27,202 The following table presents non-accrual loans as of September 30, 2022 by class and year of origination. 2022 2021 2020 2019 2018 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial and industrial $ — $ 85 $ 1,065 $ 3,245 $ 1,439 $ 234 $ 467 $ 732 $ 7,267 Energy 5,154 — 72 1,394 15 — 7,746 1,753 16,134 Paycheck Protection Program — — — — — — — — — Commercial real estate: Buildings, land and other 1,083 2,408 — 223 275 1,500 — — 5,489 Construction — — — — — — — — — Consumer real estate — — — — — 363 — 651 1,014 Consumer and other — — — — — — — — — Total $ 6,237 $ 2,493 $ 1,137 $ 4,862 $ 1,729 $ 2,097 $ 8,213 $ 3,136 $ 29,904 Had non-accrual loans performed in accordance with their original contract terms, we would have recognized additional interest income, net of tax, of approximately $372 thousand and $1.2 million for the three and nine months ended September 30, 2022, respectively, and approximately $474 thousand and $1.4 million for the three and nine months ended September 30, 2021, respectively. An age analysis of past due loans (including both accruing and non-accruing loans), segregated by class of loans, as of September 30, 2022 was as follows: Loans Loans Total Current Total Accruing Commercial and industrial $ 26,481 $ 4,629 $ 31,110 $ 5,500,710 $ 5,531,820 $ 2,443 Energy 2,211 7,745 9,956 908,169 918,125 — Paycheck Protection Program 13,841 7,879 21,720 29,328 51,048 7,879 Commercial real estate: Buildings, land and other 20,434 2,341 22,775 6,651,152 6,673,927 1,731 Construction 1,238 — 1,238 1,556,177 1,557,415 — Consumer real estate 7,169 2,110 9,279 1,706,457 1,715,736 1,803 Consumer and other 5,611 491 6,102 496,456 502,558 491 Total $ 76,985 $ 25,195 $ 102,180 $ 16,848,449 $ 16,950,629 $ 14,347 Troubled Debt Restructurings . Troubled debt restructurings during the nine months ended September 30, 2022 and 2021 are set forth in the following table. Nine Months Ended Nine Months Ended Balance at Balance at Balance at Balance at Commercial and industrial $ — $ — $ 1,312 $ 1,237 Energy — — 3,817 3,566 Commercial real estate: Buildings, land and other 1,155 1,083 1,888 1,875 $ 1,155 $ 1,083 $ 7,017 $ 6,678 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. The modifications during the reported periods did not significantly impact our determination of the allowance for credit losses on loans. Information as of or for the nine months ended September 30, 2022 and 2021 related to loans restructured during the preceding twelve months is set forth in the following table. September 30, 2022 September 30, 2021 Restructured loans past due in excess of 90 days at period-end: Number of loans — 1 Dollar amount of loans $ — $ 306 Restructured loans on non-accrual status at period end 1,083 5,072 Charge-offs of restructured loans: Recognized in connection with restructuring — — Recognized on previously restructured loans 723 1,433 Proceeds from sale of restructured loans 1,070 — 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 (v) 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 September 30, 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 $ 1,214,942 $ 706,035 $ 529,894 $ 242,581 $ 136,161 $ 199,629 $ 2,180,437 $ 47,088 $ 5,256,767 6.25 Risk grade 9 34,065 28,895 6,211 6,909 12,436 9,923 94,984 11,133 204,556 9.00 Risk grade 10 2,131 636 814 4,513 1,518 143 21,207 2,207 33,169 10.00 Risk grade 11 35 3,984 6,444 4,332 1,391 1,942 8,188 3,745 30,061 11.00 Risk grade 12 — 85 837 2,975 1,419 234 467 436 6,453 12.00 Risk grade 13 — — 228 270 20 — — 296 814 13.00 $ 1,251,173 $ 739,635 $ 544,428 $ 261,580 $ 152,945 $ 211,871 $ 2,305,283 $ 64,905 $ 5,531,820 6.41 W/A risk grade 6.44 7.05 6.04 6.66 6.92 5.73 6.25 7.57 6.41 Energy Risk grades 1-8 $ 319,910 $ 105,110 $ 5,238 $ 5,674 $ 2,346 $ 4,146 $ 386,836 $ 45,123 $ 874,383 5.61 Risk grade 9 1,722 147 245 659 829 — 10,016 35 13,653 9.00 Risk grade 10 — — — 456 226 — — 47 729 10.00 Risk grade 11 8,714 186 173 3,183 819 151 — — 13,226 11.00 Risk grade 12 4,104 — 72 1,394 15 — 4,571 303 10,459 12.00 Risk grade 13 1,050 — — — — — 3,175 1,450 5,675 13.00 $ 335,500 $ 105,443 $ 5,728 $ 11,366 $ 4,235 $ 4,297 $ 404,598 $ 46,958 $ 918,125 5.86 W/A risk grade 6.22 5.64 7.67 8.81 8.52 6.70 5.40 6.46 5.86 Commercial real estate: Buildings, land, other Risk grades 1-8 $ 1,434,936 $ 1,556,836 $ 936,889 $ 731,589 $ 361,215 $ 868,933 $ 101,817 $ 105,168 $ 6,097,383 6.91 Risk grade 9 51,425 20,259 109,106 79,833 24,749 54,595 4,558 2,134 346,659 9.00 Risk grade 10 33,233 14,484 11,364 42,672 29,990 6,012 — — 137,755 10.00 Risk grade 11 12,808 14,684 4,520 6,393 6,401 38,266 2,993 576 86,641 11.00 Risk grade 12 613 2,082 — 223 275 1,500 — — 4,693 12.00 Risk grade 13 470 326 — — — — — — 796 13.00 $ 1,533,485 $ 1,608,671 $ 1,061,879 $ 860,710 $ 422,630 $ 969,306 $ 109,368 $ 107,878 $ 6,673,927 7.14 W/A risk grade 7.11 7.19 7.27 7.20 7.35 6.90 7.26 6.45 7.14 Construction Risk grades 1-8 $ 464,837 $ 568,694 $ 162,262 $ 35,986 $ 490 $ 1,762 $ 243,723 $ 4,414 $ 1,482,168 6.85 Risk grade 9 11,270 2,253 2,100 — — — 17,382 — 33,005 9.00 Risk grade 10 28,851 75 — — — — — — 28,926 10.00 Risk grade 11 — — — 13,316 — — — — 13,316 11.00 Risk grade 12 — — — — — — — — — 12.00 Risk grade 13 — — — — — — — — — 13.00 $ 504,958 $ 571,022 $ 164,362 $ 49,302 $ 490 $ 1,762 $ 261,105 $ 4,414 $ 1,557,415 6.99 W/A risk grade 7.11 7.21 6.55 8.08 6.00 6.76 6.36 5.01 6.99 Total commercial real estate $ 2,038,443 $ 2,179,693 $ 1,226,241 $ 910,012 $ 423,120 $ 971,068 $ 370,473 $ 112,292 $ 8,231,342 7.11 W/A risk grade 7.11 7.20 7.17 7.24 7.35 6.90 6.63 6.39 7.11 In the table above, certain 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 September 30, 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 $ 90 $ 726 $ 689 $ 503 $ 405 $ 1,605 $ 1,549 $ 1,602 $ 7,169 Past due 90 or more days — — 64 341 151 1,116 208 230 2,110 Total past due 90 726 753 844 556 2,721 1,757 1,832 9,279 Current loans 283,431 317,862 201,281 74,855 41,146 129,830 649,300 8,752 1,706,457 Total $ 283,521 $ 318,588 $ 202,034 $ 75,699 $ 41,702 $ 132,551 $ 651,057 $ 10,584 $ 1,715,736 Consumer and other: Past due 30-89 days $ 1,985 $ 245 $ 935 $ 51 $ 6 $ 43 $ 218 $ 2,128 $ 5,611 Past due 90 or more days 435 — — 16 — — 1 39 491 Total past due 2,420 245 935 67 6 43 219 2,167 6,102 Current loans 46,561 24,877 7,985 3,428 1,499 1,732 388,104 22,270 496,456 Total $ 48,981 $ 25,122 $ 8,920 $ 3,495 $ 1,505 $ 1,775 $ 388,323 $ 24,437 $ 502,558 Revolving loans that converted to term during the three and nine months ended September 30, 2022 and 2021 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Commercial and industrial $ 2,368 $ 12,009 $ 22,579 $ 39,551 Energy 1,582 52,055 1,806 57,871 Commercial real estate: Buildings, land and other — 6,012 10,759 37,093 Construction — — 4,414 — Consumer real estate 700 330 2,223 1,172 Consumer and other 1,963 1,523 7,691 7,017 Total $ 6,613 $ 71,929 $ 49,472 $ 142,704 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 130.3 at September 30, 2022 and 135.9 at December 31, 2021. A lower TLI value implies less 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 September 30, 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. September 30, 2022 Commercial Energy Commercial Consumer Consumer Total Modeled expected credit losses $ 57,625 $ 8,657 $ 24,404 $ 7,797 $ 5,459 $ 103,942 Q-Factor and other qualitative adjustments 39,931 4,519 74,307 156 2,533 121,446 Specific allocations 1,274 5,675 1,896 82 — 8,927 Total $ 98,830 $ 18,851 $ 100,607 $ 8,035 $ 7,992 $ 234,315 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 and nine months ended September 30, 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 Energy Commercial Consumer Consumer Total Three months ended: September 30, 2022 Beginning balance $ 87,270 $ 16,267 $ 117,106 $ 6,854 $ 12,135 $ 239,632 Credit loss expense (benefit) 10,844 2,491 (16,522) 940 (216) (2,463) Charge-offs (572) — — (68) (6,549) (7,189) Recoveries 1,288 93 23 309 2,622 4,335 Net (charge-offs) recoveries 716 93 23 241 (3,927) (2,854) Ending balance $ 98,830 $ 18,851 $ 100,607 $ 8,035 $ 7,992 $ 234,315 September 30, 2021 Beginning balance $ 65,271 $ 28,010 $ 147,993 $ 6,154 $ 7,860 $ 255,288 Credit loss expense (benefit) (1,020) (7,720) 4,007 (982) 2,692 (3,023) Charge-offs (1,611) — — — (5,073) (6,684) Recoveries 1,126 159 54 857 2,373 4,569 Net (charge-offs) recoveries (485) 159 54 857 (2,700) (2,115) Ending balance $ 63,766 $ 20,449 $ 152,054 $ 6,029 $ 7,852 $ 250,150 Commercial Energy Commercial Consumer Consumer Total Nine months ended: September 30, 2022 Beginning balance $ 72,091 $ 17,217 $ 144,936 $ 6,585 $ 7,837 $ 248,666 Credit loss expense (benefit) 29,347 874 (44,363) 1,497 10,250 (2,395) Charge-offs (5,918) (371) (702) (430) (17,642) (25,063) Recoveries 3,310 1,131 736 383 7,547 13,107 Net (charge-offs) recoveries (2,608) 760 34 (47) (10,095) (11,956) Ending balance $ 98,830 $ 18,851 $ 100,607 $ 8,035 $ 7,992 $ 234,315 September 30, 2021 Beginning balance $ 73,843 $ 39,553 $ 134,892 $ 7,926 $ 6,963 $ 263,177 Credit loss expense (benefit) (8,886) (19,048) 16,583 (3,093) 7,042 (7,402) Charge-offs (4,485) (1,433) (137) (672) (13,015) (19,742) Recoveries 3,294 1,377 716 1,868 6,862 14,117 Net (charge-offs) recoveries (1,191) (56) 579 1,196 (6,153) (5,625) Ending balance $ 63,766 $ 20,449 $ 152,054 $ 6,029 $ 7,852 $ 250,150 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 September 30, 2022 and December 31, 2021. September 30, 2022 December 31, 2021 Loan Specific Allocations Loan Specific Allocations Commercial and industrial $ 8,655 $ 1,274 $ 24,523 $ 10,536 Energy 15,947 5,675 16,393 5,480 Paycheck Protection Program — — — — Commercial real estate: Buildings, land and other 19,790 1,896 24,670 200 Construction — — 948 200 Consumer real estate 934 82 303 36 Consumer and other — — — — Total $ 45,326 $ 8,927 $ 66,837 $ 16,452

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 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. September 30, December 31, Goodwill $ 654,952 $ 654,952 Other intangible assets: Core deposits $ 395 $ 718 Customer relationships 91 148 $ 486 $ 866 The estimated aggregate future amortization expense for intangible assets remaining as of September 30, 2022 is as follows: Remainder of 2022 $ 101 2023 282 2024 87 2025 11 2026 5 $ 486

Deposits

Deposits	9 Months Ended
	Sep. 30, 2022
Disclosure Text Block [Abstract]
Deposits	Deposits Deposits were as follows: September 30, December 31, Non-interest-bearing demand deposits $ 18,565,820 $ 18,423,018 Interest-bearing deposits: Savings and interest checking 12,399,351 11,930,959 Money market accounts 13,939,882 11,228,815 Time accounts 1,655,133 1,112,904 Total interest-bearing deposits 27,994,366 24,272,678 Total deposits $ 46,560,186 $ 42,695,696 The following table presents additional information about our deposits: September 30, December 31, Deposits from foreign sources (primarily Mexico) $ 1,069,964 $ 993,479 Non-interest-bearing public funds deposits 688,227 1,235,026 Interest-bearing public funds deposits 746,671 810,863 Total deposits not covered by deposit insurance 26,614,691 24,125,359 Time deposits not covered by deposit insurance 407,758 238,608

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 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: September 30, December 31, Commitments to extend credit $ 11,439,755 $ 10,420,142 Standby letters of credit 383,720 238,690 Deferred standby letter of credit fees 2,144 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 Nine Months Ended 2022 2021 2022 2021 Beginning balance $ 50,246 $ 48,596 $ 50,314 $ 44,152 Credit loss expense (benefit) 2,463 3,023 2,395 7,467 Ending balance $ 52,709 $ 51,619 $ 52,709 $ 51,619 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 Nine Months Ended 2022 2021 2022 2021 Amortization of lease right-of-use assets $ 8,389 $ 8,172 $ 24,703 $ 24,584 Short-term lease expense 536 384 1,639 1,118 Non-lease components (including taxes, insurance, common maintenance, etc.) 3,092 2,864 8,860 8,205 Total $ 12,017 $ 11,420 $ 35,202 $ 33,907 Right-of-use lease assets totaled $287.2 million at September 30, 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 $319.9 million at September 30, 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 $8.2 million and $24.6 million during the three and nine months ended September 30, 2022, respectively, and $7.9 million and $24.0 million during the three and nine months ended September 30, 2021, respectively. 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.

Capital and Regulatory Matters

Capital and Regulatory Matters	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 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 September 30, 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 September 30, 2022 and $100.0 million at December 31, 2021 and trust preferred securities totaling $120.0 million at both September 30, 2022 and December 31, 2021. The following table presents actual and required capital ratios as of September 30, 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 Plus Capital Conservation Buffer Required to be Considered Well- Capitalized (1) Capital Ratio Capital Ratio Capital Ratio September 30, 2022 Common Equity Tier 1 to Risk-Weighted Assets Cullen/Frost $ 3,606,527 12.74 % $ 1,981,042 7.00 % N/A N/A Frost Bank 3,595,393 12.71 1,979,976 7.00 1,838,550 6.50 % Tier 1 Capital to Risk-Weighted Assets Cullen/Frost 3,751,979 13.26 2,405,550 8.50 1,698,036 6.00 Frost Bank 3,595,393 12.71 2,404,257 8.50 2,262,830 8.00 Total Capital to Risk-Weighted Assets Cullen/Frost 4,187,120 14.80 2,971,562 10.50 2,830,059 10.00 Frost Bank 3,830,534 13.54 2,969,965 10.50 2,828,538 10.00 Leverage Ratio Cullen/Frost 3,751,979 7.09 2,117,091 4.00 N/A N/A Frost Bank 3,595,393 6.79 2,117,519 4.00 2,646,898 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 % N/A N/A 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 1,539,899 6.00 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 N/A N/A Frost Bank 3,261,532 6.80 1,917,679 4.00 2,397,099 5.00 ____________________ (1) “Well-capitalized” minimum Common Equity Tier 1 to Risk-Weighted Assets and Leverage Ratio are not formally defined under applicable banking regulations for bank holding companies. As of September 30, 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 September 30, 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 September 30, 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 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 September 30, 2022, Frost Bank could pay aggregate dividends of up to $619.6 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.

Derivative Financial Instrument

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 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 September 30, 2022 and December 31, 2021. September 30, 2022 December 31, 2021 Notional Estimated Notional Estimated Derivatives designated as hedges of fair value: Financial institution counterparties: Loan/lease interest rate swaps – assets $ 1,679 $ 25 $ — $ — Loan/lease interest rate swaps – liabilities — — 2,426 (34) Non-hedging interest rate derivatives: Financial institution counterparties: Loan/lease interest rate swaps – assets 1,229,040 61,992 247,592 1,207 Loan/lease interest rate swaps – liabilities 126,112 (1,088) 928,756 (19,142) Loan/lease interest rate caps – assets 243,840 15,777 270,431 3,239 Customer counterparties: Loan/lease interest rate swaps – assets 67,780 1,104 928,756 39,864 Loan/lease interest rate swaps – liabilities 1,185,815 (82,228) 247,592 (2,846) Loan/lease interest rate caps – liabilities 243,840 (15,777) 270,431 (3,239) The weighted-average rates paid and received for interest rate swaps outstanding at September 30, 2022 were as follows: Weighted-Average Interest Interest Interest rate swaps: Fair value hedge loan/lease interest rate swaps 1.58 % 2.56 % Non-hedging interest rate swaps – financial institution counterparties 3.74 4.23 Non-hedging interest rate swaps – customer counterparties 4.21 3.73 The weighted-average strike rate for outstanding interest rate caps was 3.29% at September 30, 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. September 30, 2022 December 31, 2021 Notional Notional Estimated Notional Estimated Financial institution counterparties: Oil – assets Barrels 4,467 $ 45,381 4,809 $ 14,721 Oil – liabilities Barrels 6,987 (55,645) 7,032 (73,594) Natural gas – assets MMBTUs 13,406 4,033 15,947 4,143 Natural gas – liabilities MMBTUs 20,489 (40,049) 29,446 (21,249) Customer counterparties: Oil – assets Barrels 7,006 56,366 7,046 74,437 Oil – liabilities Barrels 4,448 (44,674) 4,796 (14,294) Natural gas – assets MMBTUs 20,489 40,153 29,446 21,456 Natural gas – liabilities MMBTUs 13,406 (4,017) 15,947 (4,124) Foreign Currency Derivatives . We enter into foreign currency forward and option 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 and options 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 and option contracts were as follows: September 30, 2022 December 31, 2021 Notional Notional Estimated Notional Estimated Financial institution counterparties: Forward and option contracts – assets EUR 2,925 $ 1 1,900 $ 29 Forward and option contracts – assets CAD — — 658 — Forward and option contracts – liabilities EUR 2,925 (251) — — Customer counterparties: Forward and option contracts – assets EUR 2,925 251 — — Forward and option contracts – assets CAD — — 658 4 Forward and option contracts – liabilities EUR 2,925 (1) 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 Nine Months Ended 2022 2021 2022 2021 Commercial loan/lease interest rate swaps: Amount of gain (loss) included in interest income on loans $ 2 $ (21) $ (16) $ (74) Amount of (gain) loss included in other non-interest expense 1 3 6 8 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 Nine Months Ended 2022 2021 2022 2021 Non-hedging interest rate derivatives: Other non-interest income $ 140 $ 946 $ 1,171 $ 2,674 Other non-interest expense — — — (1) Non-hedging commodity derivatives: Other non-interest income 485 1,143 2,063 3,266 Non-hedging foreign currency derivatives: Other non-interest income — 4 63 34 Counterparty Credit Risk. Our credit exposure relating to interest rate swaps, commodity swaps/options and foreign currency forward and option contracts with bank customers was approximately $58.4 million at September 30, 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/option contracts with upstream financial institution counterparties was approximately $20.2 million at September 30, 2022. This amount was primarily related to initial margin payments to the CME and excess collateral we posted to counterparties. Excess collateral is generally cleared on the next business day. 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 September 30, 2022, the aggregate fair value of securities we posted as collateral related to derivative contracts totaled $10.9 million. We also had $12.9 million in cash collateral related to derivative contracts on deposit with other financial institution counterparties at September 30, 2022.

Balance Sheet Offsetting

Balance Sheet Offsetting	9 Months Ended
	Sep. 30, 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 September 30, 2022 is presented in the following tables. Gross Amount Gross Amount Net Amount September 30, 2022 Financial assets: Derivatives: Loan/lease interest rate swaps and caps $ 77,794 $ — $ 77,794 Commodity swaps and options 49,414 — 49,414 Foreign currency forward contracts 1 — 1 Total derivatives 127,209 — 127,209 Resell agreements 12,150 — 12,150 Total $ 139,359 $ — $ 139,359 Financial liabilities: Derivatives: Loan/lease interest rate swaps and caps $ 1,088 $ — $ 1,088 Commodity swaps and options 95,694 — 95,694 Foreign currency forward contracts 251 — 251 Total derivatives 97,033 — 97,033 Repurchase agreements 2,082,739 — 2,082,739 Total $ 2,179,772 $ — $ 2,179,772 Gross Amounts Not Offset Net Amount Financial Collateral Net September 30, 2022 Financial assets: Derivatives: Counterparty A $ 47 $ (47) $ — $ — Counterparty B 44,271 (35,853) (6,063) 2,355 Counterparty C 407 (251) — 156 Other counterparties 82,484 (53,163) (27,740) 1,581 Total derivatives 127,209 (89,314) (33,803) 4,092 Resell agreements 12,150 — (12,150) — Total $ 139,359 $ (89,314) $ (45,953) $ 4,092 Financial liabilities: Derivatives: Counterparty A $ 1,081 $ (47) $ (1,031) $ 3 Counterparty B 35,853 (35,853) — — Counterparty C 251 (251) — — Other counterparties 59,848 (53,163) (6,685) — Total derivatives 97,033 (89,314) (7,716) 3 Repurchase agreements 2,082,739 — (2,082,739) — Total $ 2,179,772 $ (89,314) $ (2,090,455) $ 3 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 Gross Amount Net Amount 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 Financial Collateral Net 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 September 30, 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 September 30, 2022 Repurchase agreements: U.S. Treasury $ 1,348,705 $ — $ — $ — $ 1,348,705 Residential mortgage-backed securities 734,034 — — — 734,034 Total borrowings $ 2,082,739 $ — $ — $ — $ 2,082,739 Gross amount of recognized liabilities for repurchase agreements $ 2,082,739 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 $ —

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 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 September 30, 2022, there were 789,290 shares remaining available for grant for future stock-based compensation awards. Deferred Non-Vested Performance Stock Options Number Weighted- Number Weighted- Number Weighted- Number Weighted- Balance, January 1, 2022 56,301 $ 79.21 449,337 $ 93.05 202,460 $ 84.71 877,681 $ 69.02 Authorized — — — — — — — — Granted 5,382 133.67 4,676 130.30 — — — — Exercised/vested (16,022) 74.89 — — (25,180) 87.18 (191,410) 61.44 Forfeited/expired — — (5,603) 93.69 (16,058) 87.18 — — Balance, September 30, 2022 45,661 87.15 448,410 93.43 161,222 84.08 686,271 71.14 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 Nine Months Ended 2022 2021 2022 2021 New shares issued from available authorized shares — — — — Shares issued from available treasury stock 88,350 21,968 232,612 650,044 Proceeds from stock option exercises $ 5,270 $ 1,128 $ 11,760 $ 37,810 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 Nine Months Ended 2022 2021 2022 2021 Non-vested stock units $ 2,174 $ 1,559 $ 6,823 $ 5,210 Deferred stock units — — 720 700 Performance stock units 999 426 1,160 1,846 Total $ 3,173 $ 1,985 $ 8,703 $ 7,756 Income tax benefit $ 440 $ 281 $ 1,760 $ 1,162 Unrecognized stock-based compensation expense at September 30, 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 $ 11,704 Performance stock units 7,257 Total $ 18,961

Earnings Per Common Share

Earnings Per Common Share	9 Months Ended
	Sep. 30, 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 Nine Months Ended 2022 2021 2022 2021 Net income $ 169,760 $ 107,975 $ 387,976 $ 342,058 Less: Preferred stock dividends 1,668 1,668 5,006 5,488 Net income available to common shareholders 168,092 106,307 382,970 336,570 Less: Earnings allocated to participating securities 1,503 932 3,414 3,228 Net earnings allocated to common stock $ 166,589 $ 105,375 $ 379,556 $ 333,342 Distributed earnings allocated to common stock $ 55,820 $ 47,740 $ 151,963 $ 139,224 Undistributed earnings allocated to common stock 110,769 57,635 227,593 194,118 Net earnings allocated to common stock $ 166,589 $ 105,375 $ 379,556 $ 333,342 Weighted-average shares outstanding for basic earnings per common share 64,157,662 63,652,020 64,107,621 63,522,884 Dilutive effect of stock compensation 343,750 444,636 369,268 489,219 Weighted-average shares outstanding for diluted earnings per common share 64,501,412 64,096,656 64,476,889 64,012,103

Defined Benefit Plans

Defined Benefit Plans	9 Months Ended
	Sep. 30, 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 Nine Months Ended 2022 2021 2022 2021 Expected return on plan assets, net of expenses $ (3,492) $ (3,210) $ (10,475) $ (9,630) Interest cost on projected benefit obligation 1,005 835 3,013 2,506 Net amortization and deferral 741 1,529 2,223 4,587 Net periodic expense (benefit) $ (1,746) $ (846) $ (5,239) $ (2,537) Our non-qualified defined benefit pension plan is not funded. No contributions to the qualified defined benefit pension plan were made during the nine months ended September 30, 2022. We do not expect to make any contributions to the qualified defined benefit plan during the remainder of 2022.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense was as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Current income tax expense (benefit) $ 28,684 $ 13,849 $ 64,389 $ 31,639 Deferred income tax expense (benefit) (974) (516) (3,378) 4,672 Income tax expense, as reported $ 27,710 $ 13,333 $ 61,011 $ 36,311 Effective tax rate 14.0 % 11.0 % 13.6 % 9.6 % We had a net deferred tax asset totaling $420.9 million at September 30, 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 September 30, 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.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	9 Months Ended
	Sep. 30, 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 Three Months Ended Before Tax Tax Expense, Net of Tax Before Tax Tax Expense, Net of Tax Securities available for sale and transferred securities: Change in net unrealized gain/loss during the period $ (829,324) $ (174,158) $ (655,166) $ (80,668) $ (16,941) $ (63,727) Change in net unrealized gain on securities transferred to held to maturity (174) (36) (138) (237) (49) (188) Reclassification adjustment for net (gains) losses included in net income — — — — — — Total securities available for sale and transferred securities (829,498) (174,194) (655,304) (80,905) (16,990) (63,915) 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) 741 156 585 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) $ (828,757) $ (174,038) $ (654,719) $ (79,376) $ (16,669) $ (62,707) Nine Months Ended Nine Months Ended Before Tax Tax Expense, Net of Tax Before Tax Tax Expense, Net of Tax Securities available for sale and transferred securities: Change in net unrealized gain/loss during the period $ (2,376,642) $ (499,095) $ (1,877,547) $ (209,779) $ (44,054) $ (165,725) Change in net unrealized gain on securities transferred to held to maturity (572) (120) (452) (741) (155) (586) Reclassification adjustment for net (gains) losses included in net income — — — — — — Total securities available for sale and transferred securities (2,377,214) (499,215) (1,877,999) (210,520) (44,209) (166,311) 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) 2,223 467 1,756 4,587 963 3,624 Total defined-benefit post-retirement benefit plans 2,223 467 1,756 4,587 963 3,624 Total other comprehensive income (loss) $ (2,374,991) $ (498,748) $ (1,876,243) $ (205,933) $ (43,246) $ (162,687) Activity in accumulated other comprehensive income (loss), net of tax, was as follows: Securities Defined Accumulated Balance January 1, 2022 $ 380,209 $ (32,891) $ 347,318 Other comprehensive income (loss) before reclassifications (1,877,999) — (1,877,999) Reclassification of amounts included in net income — 1,756 1,756 Net other comprehensive income (loss) during period (1,877,999) 1,756 (1,876,243) Balance at September 30, 2022 $ (1,497,790) $ (31,135) $ (1,528,925) Balance January 1, 2021 $ 563,801 $ (50,831) $ 512,970 Other comprehensive income (loss) before reclassifications (166,311) — (166,311) Reclassification of amounts included in net income — 3,624 3,624 Net other comprehensive income (loss) during period (166,311) 3,624 (162,687) Balance at September 30, 2021 $ 397,490 $ (47,207) $ 350,283

Operating Segments

Operating Segments	9 Months Ended
	Sep. 30, 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 Non-Banks Consolidated Three months ended: September 30, 2022 Net interest income (expense) $ 356,513 $ 1,357 $ (2,323) $ 355,547 Credit loss expense (1) 1 — — Non-interest income 55,994 44,263 (436) 99,821 Non-interest expense 223,193 33,530 1,175 257,898 Income (loss) before income taxes 189,315 12,089 (3,934) 197,470 Income tax expense (benefit) 26,520 2,539 (1,349) 27,710 Net income (loss) 162,795 9,550 (2,585) 169,760 Preferred stock dividends — — 1,668 1,668 Net income (loss) available to common shareholders $ 162,795 $ 9,550 $ (4,253) $ 168,092 Revenues from (expenses to) external customers $ 412,507 $ 45,620 $ (2,759) $ 455,368 September 30, 2021 Net interest income (expense) $ 247,381 $ 536 $ (1,795) $ 246,122 Credit loss expense (benefit) (6) 6 — — Non-interest income 51,279 42,369 (459) 93,189 Non-interest expense 185,891 31,086 1,026 218,003 Income (loss) before income taxes 112,775 11,813 (3,280) 121,308 Income tax expense (benefit) 12,029 2,481 (1,177) 13,333 Net income (loss) 100,746 9,332 (2,103) 107,975 Preferred stock dividends — — 1,668 1,668 Net income (loss) available to common shareholders $ 100,746 $ 9,332 $ (3,771) $ 106,307 Revenues from (expenses to) external customers $ 298,660 $ 42,905 $ (2,254) $ 339,311 Nine months ended: September 30, 2022 Net interest income (expense) $ 895,818 $ 3,015 $ (6,007) $ 892,826 Credit loss expense (benefit) (1) 1 — — Non-interest income 170,097 130,546 (1,505) 299,138 Non-interest expense 640,775 97,598 4,604 742,977 Income (loss) before income taxes 425,141 35,962 (12,116) 448,987 Income tax expense (benefit) 57,355 7,552 (3,896) 61,011 Net income (loss) 367,786 28,410 (8,220) 387,976 Preferred stock dividends — — 5,006 5,006 Net income (loss) available to common shareholders $ 367,786 $ 28,410 $ (13,226) $ 382,970 Revenues from (expenses to) external customers $ 1,065,915 $ 133,561 $ (7,512) $ 1,191,964 September 30, 2021 Net interest income (expense) $ 748,036 $ 1,530 $ (5,407) $ 744,159 Credit loss expense 57 6 — 63 Non-interest income 154,003 124,512 (843) 277,672 Non-interest expense 548,151 91,037 4,211 643,399 Income (loss) before income taxes 353,831 34,999 (10,461) 378,369 Income tax expense (benefit) 32,811 7,350 (3,850) 36,311 Net income (loss) 321,020 27,649 (6,611) 342,058 Preferred stock dividends — — 5,488 5,488 Net income (loss) available to common shareholders $ 321,020 $ 27,649 $ (12,099) $ 336,570 Revenues from (expenses to) external customers $ 902,039 $ 126,042 $ (6,250) $ 1,021,831

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 2022 Securities available for sale: U.S. Treasury $ 5,022,617 $ — $ — $ 5,022,617 Residential mortgage-backed securities — 5,698,809 — 5,698,809 States and political subdivisions — 6,635,298 — 6,635,298 Other — 42,383 — 42,383 Trading account securities: U.S. Treasury 25,008 — — 25,008 Derivative assets: Interest rate swaps, caps and floors — 78,898 — 78,898 Commodity swaps and options — 145,933 — 145,933 Foreign currency forward contracts 252 — — 252 Derivative liabilities: Interest rate swaps, caps and floors — 99,093 — 99,093 Commodity swaps and options — 144,385 — 144,385 Foreign currency forward contracts 252 — — 252 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. Nine Months Ended Nine Months Ended Level 2 Level 3 Level 2 Level 3 Carrying value before allocations $ 7,999 $ 2,087 $ 3,329 $ 15,274 Specific (allocations) reversals of prior allocations (1,742) 4,881 (336) (4,791) Fair value $ 6,257 $ 6,968 $ 2,993 $ 10,483 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: September 30, 2022 December 31, 2021 Carrying Estimated Carrying Estimated Financial assets: Level 2 inputs: Cash and cash equivalents $ 13,632,698 $ 13,632,698 $ 16,583,000 $ 16,583,000 Securities held to maturity 2,174,084 1,917,287 1,749,179 1,809,143 Cash surrender value of life insurance policies 190,368 190,368 190,139 190,139 Accrued interest receivable 169,540 169,540 179,111 179,111 Level 3 inputs: Loans, net 16,716,314 16,163,170 16,087,731 16,079,454 Financial liabilities: Level 2 inputs: Deposits 46,560,186 46,538,352 42,695,696 41,343,426 Federal funds purchased 26,200 26,200 25,925 25,925 Repurchase agreements 2,082,739 2,082,739 2,740,799 2,740,799 Junior subordinated deferrable interest debentures 123,055 123,712 123,011 123,712 Subordinated notes 99,295 96,926 99,178 111,430 Accrued interest payable 9,545 9,545 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.

Accounting Standards Updates

Accounting Standards Updates	9 Months Ended
	Sep. 30, 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. ASU 2022-03, “Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions.” ASU 2022-03 clarifies that a contractual restriction on the sale of an equity security is not considered part of the unit of account of the equity security and, therefore, is not considered in measuring fair value. ASU 2022-03 also clarifies that an entity cannot, as a separate unit of account, recognize and measure a contractual sale restriction and requires certain new disclosures for equity securities subject to contractual sale restrictions. ASU 2022-03 will be effective for us on January 1, 2024 though early adoption is permitted. The adoption of ASU 2022-03 is not expected to have a significant impact on our financial statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 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.

Loans Loans - Allowance For Cre

Loans Loans - Allowance For Credit Losses (Policies)	9 Months Ended
	Sep. 30, 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.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2022
Accounting Policies [Abstract]
Additional Cash Flow Information	Additional cash flow information was as follows: Nine Months Ended 2022 2021 Cash paid for interest $ 71,848 $ 23,722 Cash paid for income taxes 78,500 28,043 Significant non-cash transactions: Unsettled securities transactions 470,813 600,874 Loans foreclosed and transferred to other real estate owned and foreclosed assets — 3,464 Right-of-use lease assets obtained in exchange for lessee operating lease liabilities 23,959 4,045 Treasury stock issued to 401(k) stock purchase plan — 1,749

Securities (Tables)

Securities (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2022 and December 31, 2021 is presented below. Amortized Gross Gross Estimated Allowance Net September 30, 2022 Residential mortgage-backed securities $ 526,397 $ — $ 68,024 $ 458,373 $ — $ 526,397 States and political subdivisions 1,646,345 90 188,964 1,457,471 (158) 1,646,187 Other 1,500 — 57 1,443 — 1,500 Total $ 2,174,242 $ 90 $ 257,045 $ 1,917,287 $ (158) $ 2,174,084 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 September 30, 2022 and December 31, 2021: States and Political Subdivisions Not Guaranteed or Pre-Refunded Guaranteed by the Texas PSF Pre-Refunded Total Other September 30, 2022 Aaa/AAA $ 220,180 $ 1,116,482 $ 121,042 $ 1,457,704 $ — Aa/AA 188,641 — — 188,641 — Not rated — — — — 1,500 Total $ 408,821 $ 1,116,482 $ 121,042 $ 1,646,345 $ 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 and nine months ended September 30, 2022 and 2021. Three Months Ended Nine Months Ended 2022 2021 2022 2021 Beginning balance $ 158 $ 158 $ 158 $ 160 Credit loss expense (benefit) — — — (2) Ending balance $ 158 $ 158 $ 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 September 30, 2022 and December 31, 2021 is presented below. Amortized Gross Gross Allowance Estimated September 30, 2022 U.S. Treasury $ 5,447,478 $ — $ 424,861 $ — $ 5,022,617 Residential mortgage-backed securities 6,685,418 1,293 987,902 — 5,698,809 States and political subdivisions 7,121,730 1,395 487,827 — 6,635,298 Other 42,383 — — — 42,383 Total $ 19,297,009 $ 2,688 $ 1,900,590 $ — $ 17,399,107 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 September 30, 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 Unrealized Estimated Unrealized Estimated Unrealized U.S. Treasury $ 4,429,609 $ 323,346 $ 593,008 $ 101,515 $ 5,022,617 $ 424,861 Residential mortgage-backed securities 4,280,074 713,685 1,032,311 274,217 5,312,385 987,902 States and political subdivisions 5,943,551 412,938 194,456 74,889 6,138,007 487,827 Total $ 14,653,234 $ 1,449,969 $ 1,819,775 $ 450,621 $ 16,473,009 $ 1,900,590
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 September 30, 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 $ — $ — $ 514,321 $ 12,076 $ 526,397 States and political subdivisions 121,042 29,534 9,880 1,485,889 1,646,345 Other — 1,500 — — 1,500 Total $ 121,042 $ 31,034 $ 524,201 $ 1,497,965 $ 2,174,242 Estimated Fair Value Residential mortgage-backed securities $ — $ — $ 448,514 $ 9,859 $ 458,373 States and political subdivisions 120,786 29,362 9,850 1,297,473 1,457,471 Other — 1,443 — — 1,443 Total $ 120,786 $ 30,805 $ 458,364 $ 1,307,332 $ 1,917,287 Available For Sale Amortized Cost U. S. Treasury $ — $ 3,821,606 $ 1,433,912 $ 191,960 $ 5,447,478 Residential mortgage-backed securities 28 9,355 17,253 6,658,782 6,685,418 States and political subdivisions 250,317 1,470,384 944,279 4,456,750 7,121,730 Other — — — — 42,383 Total $ 250,345 $ 5,301,345 $ 2,395,444 $ 11,307,492 $ 19,297,009 Estimated Fair Value U. S. Treasury $ — $ 3,648,015 $ 1,232,969 $ 141,633 $ 5,022,617 Residential mortgage-backed securities 27 9,130 17,167 5,672,485 5,698,809 States and political subdivisions 250,875 1,462,732 894,174 4,027,517 6,635,298 Other — — — — 42,383 Total $ 250,902 $ 5,119,877 $ 2,144,310 $ 9,841,635 $ 17,399,107
Investment Income	Premium amortization and discount accretion included in interest income on securities was as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Premium amortization $ (27,165) $ (30,240) $ (84,278) $ (92,016) Discount accretion 4,062 657 7,950 1,999 Net (premium amortization) discount accretion $ (23,103) $ (29,583) $ (76,328) $ (90,017)
Trading Account Securities, at Estimated Fair Value	Trading account securities, at estimated fair value, were as follows: September 30, December 31, U.S. Treasury $ 25,008 $ 24,237 States and political subdivisions — 925 Total $ 25,008 $ 25,162
Net Gains and Losses on Trading Account Securities	Net gains and losses on trading account securities were as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Net gain on sales transactions $ 1,110 $ 314 $ 2,462 $ 716 Net mark-to-market gains (losses) 9 (2) (235) (71) Net gain (loss) on trading account securities $ 1,119 $ 312 $ 2,227 $ 645

Loans (Tables)

Loans (Tables)	9 Months Ended
	Sep. 30, 2022
Receivables [Abstract]
Loans	Loans were as follows: September 30, December 31, Commercial and industrial $ 5,531,820 $ 5,364,954 Energy: Production 701,975 878,436 Service 127,065 105,901 Other 89,085 93,455 Total energy 918,125 1,077,792 Paycheck Protection Program 51,048 428,882 Commercial real estate: Commercial mortgages 6,149,504 5,867,062 Construction 1,557,415 1,304,271 Land 524,423 405,277 Total commercial real estate 8,231,342 7,576,610 Consumer real estate: Home equity loans 401,234 324,157 Home equity lines of credit 661,618 519,098 Other 652,884 567,535 Total consumer real estate 1,715,736 1,410,790 Total real estate 9,947,078 8,987,400 Consumer and other 502,558 477,369 Total loans $ 16,950,629 $ 16,336,397
Non-Accrual Loans, Segregated by Class of Loans	Non-accrual loans, segregated by class of loans, were as follows: September 30, 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 $ 7,267 $ 4,425 $ 22,582 $ 4,701 Energy 16,134 7,277 14,433 8,533 Paycheck Protection Program — — — — Commercial real estate: Buildings, land and other 5,489 2,497 15,297 13,817 Construction — — 948 — Consumer real estate 1,014 712 440 138 Consumer and other — — 13 13 Total $ 29,904 $ 14,911 $ 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 September 30, 2022 by class and year of origination. 2022 2021 2020 2019 2018 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial and industrial $ — $ 85 $ 1,065 $ 3,245 $ 1,439 $ 234 $ 467 $ 732 $ 7,267 Energy 5,154 — 72 1,394 15 — 7,746 1,753 16,134 Paycheck Protection Program — — — — — — — — — Commercial real estate: Buildings, land and other 1,083 2,408 — 223 275 1,500 — — 5,489 Construction — — — — — — — — — Consumer real estate — — — — — 363 — 651 1,014 Consumer and other — — — — — — — — — Total $ 6,237 $ 2,493 $ 1,137 $ 4,862 $ 1,729 $ 2,097 $ 8,213 $ 3,136 $ 29,904
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 September 30, 2022 was as follows: Loans Loans Total Current Total Accruing Commercial and industrial $ 26,481 $ 4,629 $ 31,110 $ 5,500,710 $ 5,531,820 $ 2,443 Energy 2,211 7,745 9,956 908,169 918,125 — Paycheck Protection Program 13,841 7,879 21,720 29,328 51,048 7,879 Commercial real estate: Buildings, land and other 20,434 2,341 22,775 6,651,152 6,673,927 1,731 Construction 1,238 — 1,238 1,556,177 1,557,415 — Consumer real estate 7,169 2,110 9,279 1,706,457 1,715,736 1,803 Consumer and other 5,611 491 6,102 496,456 502,558 491 Total $ 76,985 $ 25,195 $ 102,180 $ 16,848,449 $ 16,950,629 $ 14,347
Troubled debt restructurings	Troubled debt restructurings during the nine months ended September 30, 2022 and 2021 are set forth in the following table. Nine Months Ended Nine Months Ended Balance at Balance at Balance at Balance at Commercial and industrial $ — $ — $ 1,312 $ 1,237 Energy — — 3,817 3,566 Commercial real estate: Buildings, land and other 1,155 1,083 1,888 1,875 $ 1,155 $ 1,083 $ 7,017 $ 6,678
Restructured Loans Past Due in Excess of 90 Days on Financing Receivables	Information as of or for the nine months ended September 30, 2022 and 2021 related to loans restructured during the preceding twelve months is set forth in the following table. September 30, 2022 September 30, 2021 Restructured loans past due in excess of 90 days at period-end: Number of loans — 1 Dollar amount of loans $ — $ 306 Restructured loans on non-accrual status at period end 1,083 5,072 Charge-offs of restructured loans: Recognized in connection with restructuring — — Recognized on previously restructured loans 723 1,433 Proceeds from sale of restructured loans 1,070 —
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 September 30, 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 $ 1,214,942 $ 706,035 $ 529,894 $ 242,581 $ 136,161 $ 199,629 $ 2,180,437 $ 47,088 $ 5,256,767 6.25 Risk grade 9 34,065 28,895 6,211 6,909 12,436 9,923 94,984 11,133 204,556 9.00 Risk grade 10 2,131 636 814 4,513 1,518 143 21,207 2,207 33,169 10.00 Risk grade 11 35 3,984 6,444 4,332 1,391 1,942 8,188 3,745 30,061 11.00 Risk grade 12 — 85 837 2,975 1,419 234 467 436 6,453 12.00 Risk grade 13 — — 228 270 20 — — 296 814 13.00 $ 1,251,173 $ 739,635 $ 544,428 $ 261,580 $ 152,945 $ 211,871 $ 2,305,283 $ 64,905 $ 5,531,820 6.41 W/A risk grade 6.44 7.05 6.04 6.66 6.92 5.73 6.25 7.57 6.41 Energy Risk grades 1-8 $ 319,910 $ 105,110 $ 5,238 $ 5,674 $ 2,346 $ 4,146 $ 386,836 $ 45,123 $ 874,383 5.61 Risk grade 9 1,722 147 245 659 829 — 10,016 35 13,653 9.00 Risk grade 10 — — — 456 226 — — 47 729 10.00 Risk grade 11 8,714 186 173 3,183 819 151 — — 13,226 11.00 Risk grade 12 4,104 — 72 1,394 15 — 4,571 303 10,459 12.00 Risk grade 13 1,050 — — — — — 3,175 1,450 5,675 13.00 $ 335,500 $ 105,443 $ 5,728 $ 11,366 $ 4,235 $ 4,297 $ 404,598 $ 46,958 $ 918,125 5.86 W/A risk grade 6.22 5.64 7.67 8.81 8.52 6.70 5.40 6.46 5.86 Commercial real estate: Buildings, land, other Risk grades 1-8 $ 1,434,936 $ 1,556,836 $ 936,889 $ 731,589 $ 361,215 $ 868,933 $ 101,817 $ 105,168 $ 6,097,383 6.91 Risk grade 9 51,425 20,259 109,106 79,833 24,749 54,595 4,558 2,134 346,659 9.00 Risk grade 10 33,233 14,484 11,364 42,672 29,990 6,012 — — 137,755 10.00 Risk grade 11 12,808 14,684 4,520 6,393 6,401 38,266 2,993 576 86,641 11.00 Risk grade 12 613 2,082 — 223 275 1,500 — — 4,693 12.00 Risk grade 13 470 326 — — — — — — 796 13.00 $ 1,533,485 $ 1,608,671 $ 1,061,879 $ 860,710 $ 422,630 $ 969,306 $ 109,368 $ 107,878 $ 6,673,927 7.14 W/A risk grade 7.11 7.19 7.27 7.20 7.35 6.90 7.26 6.45 7.14 Construction Risk grades 1-8 $ 464,837 $ 568,694 $ 162,262 $ 35,986 $ 490 $ 1,762 $ 243,723 $ 4,414 $ 1,482,168 6.85 Risk grade 9 11,270 2,253 2,100 — — — 17,382 — 33,005 9.00 Risk grade 10 28,851 75 — — — — — — 28,926 10.00 Risk grade 11 — — — 13,316 — — — — 13,316 11.00 Risk grade 12 — — — — — — — — — 12.00 Risk grade 13 — — — — — — — — — 13.00 $ 504,958 $ 571,022 $ 164,362 $ 49,302 $ 490 $ 1,762 $ 261,105 $ 4,414 $ 1,557,415 6.99 W/A risk grade 7.11 7.21 6.55 8.08 6.00 6.76 6.36 5.01 6.99 Total commercial real estate $ 2,038,443 $ 2,179,693 $ 1,226,241 $ 910,012 $ 423,120 $ 971,068 $ 370,473 $ 112,292 $ 8,231,342 7.11 W/A risk grade 7.11 7.20 7.17 7.24 7.35 6.90 6.63 6.39 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 September 30, 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 $ 90 $ 726 $ 689 $ 503 $ 405 $ 1,605 $ 1,549 $ 1,602 $ 7,169 Past due 90 or more days — — 64 341 151 1,116 208 230 2,110 Total past due 90 726 753 844 556 2,721 1,757 1,832 9,279 Current loans 283,431 317,862 201,281 74,855 41,146 129,830 649,300 8,752 1,706,457 Total $ 283,521 $ 318,588 $ 202,034 $ 75,699 $ 41,702 $ 132,551 $ 651,057 $ 10,584 $ 1,715,736 Consumer and other: Past due 30-89 days $ 1,985 $ 245 $ 935 $ 51 $ 6 $ 43 $ 218 $ 2,128 $ 5,611 Past due 90 or more days 435 — — 16 — — 1 39 491 Total past due 2,420 245 935 67 6 43 219 2,167 6,102 Current loans 46,561 24,877 7,985 3,428 1,499 1,732 388,104 22,270 496,456 Total $ 48,981 $ 25,122 $ 8,920 $ 3,495 $ 1,505 $ 1,775 $ 388,323 $ 24,437 $ 502,558
Revolving Loans Converted to Term [Table Text Block]	Revolving loans that converted to term during the three and nine months ended September 30, 2022 and 2021 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Commercial and industrial $ 2,368 $ 12,009 $ 22,579 $ 39,551 Energy 1,582 52,055 1,806 57,871 Commercial real estate: Buildings, land and other — 6,012 10,759 37,093 Construction — — 4,414 — Consumer real estate 700 330 2,223 1,172 Consumer and other 1,963 1,523 7,691 7,017 Total $ 6,613 $ 71,929 $ 49,472 $ 142,704
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 September 30, 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. September 30, 2022 Commercial Energy Commercial Consumer Consumer Total Modeled expected credit losses $ 57,625 $ 8,657 $ 24,404 $ 7,797 $ 5,459 $ 103,942 Q-Factor and other qualitative adjustments 39,931 4,519 74,307 156 2,533 121,446 Specific allocations 1,274 5,675 1,896 82 — 8,927 Total $ 98,830 $ 18,851 $ 100,607 $ 8,035 $ 7,992 $ 234,315 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 and nine months ended September 30, 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 Energy Commercial Consumer Consumer Total Three months ended: September 30, 2022 Beginning balance $ 87,270 $ 16,267 $ 117,106 $ 6,854 $ 12,135 $ 239,632 Credit loss expense (benefit) 10,844 2,491 (16,522) 940 (216) (2,463) Charge-offs (572) — — (68) (6,549) (7,189) Recoveries 1,288 93 23 309 2,622 4,335 Net (charge-offs) recoveries 716 93 23 241 (3,927) (2,854) Ending balance $ 98,830 $ 18,851 $ 100,607 $ 8,035 $ 7,992 $ 234,315 September 30, 2021 Beginning balance $ 65,271 $ 28,010 $ 147,993 $ 6,154 $ 7,860 $ 255,288 Credit loss expense (benefit) (1,020) (7,720) 4,007 (982) 2,692 (3,023) Charge-offs (1,611) — — — (5,073) (6,684) Recoveries 1,126 159 54 857 2,373 4,569 Net (charge-offs) recoveries (485) 159 54 857 (2,700) (2,115) Ending balance $ 63,766 $ 20,449 $ 152,054 $ 6,029 $ 7,852 $ 250,150 Commercial Energy Commercial Consumer Consumer Total Nine months ended: September 30, 2022 Beginning balance $ 72,091 $ 17,217 $ 144,936 $ 6,585 $ 7,837 $ 248,666 Credit loss expense (benefit) 29,347 874 (44,363) 1,497 10,250 (2,395) Charge-offs (5,918) (371) (702) (430) (17,642) (25,063) Recoveries 3,310 1,131 736 383 7,547 13,107 Net (charge-offs) recoveries (2,608) 760 34 (47) (10,095) (11,956) Ending balance $ 98,830 $ 18,851 $ 100,607 $ 8,035 $ 7,992 $ 234,315 September 30, 2021 Beginning balance $ 73,843 $ 39,553 $ 134,892 $ 7,926 $ 6,963 $ 263,177 Credit loss expense (benefit) (8,886) (19,048) 16,583 (3,093) 7,042 (7,402) Charge-offs (4,485) (1,433) (137) (672) (13,015) (19,742) Recoveries 3,294 1,377 716 1,868 6,862 14,117 Net (charge-offs) recoveries (1,191) (56) 579 1,196 (6,153) (5,625) Ending balance $ 63,766 $ 20,449 $ 152,054 $ 6,029 $ 7,852 $ 250,150
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 September 30, 2022 and December 31, 2021. September 30, 2022 December 31, 2021 Loan Specific Allocations Loan Specific Allocations Commercial and industrial $ 8,655 $ 1,274 $ 24,523 $ 10,536 Energy 15,947 5,675 16,393 5,480 Paycheck Protection Program — — — — Commercial real estate: Buildings, land and other 19,790 1,896 24,670 200 Construction — — 948 200 Consumer real estate 934 82 303 36 Consumer and other — — — — Total $ 45,326 $ 8,927 $ 66,837 $ 16,452

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Goodwill	Goodwill and other intangible assets are presented in the table below. September 30, December 31, Goodwill $ 654,952 $ 654,952 Other intangible assets: Core deposits $ 395 $ 718 Customer relationships 91 148 $ 486 $ 866
Estimated Aggregate Future Amortization Expense for Intangible Assets	The estimated aggregate future amortization expense for intangible assets remaining as of September 30, 2022 is as follows: Remainder of 2022 $ 101 2023 282 2024 87 2025 11 2026 5 $ 486

Deposits (Tables)

Deposits (Tables)	9 Months Ended
	Sep. 30, 2022
Disclosure Text Block [Abstract]
Deposit Liabilities, Type	Deposits were as follows: September 30, December 31, Non-interest-bearing demand deposits $ 18,565,820 $ 18,423,018 Interest-bearing deposits: Savings and interest checking 12,399,351 11,930,959 Money market accounts 13,939,882 11,228,815 Time accounts 1,655,133 1,112,904 Total interest-bearing deposits 27,994,366 24,272,678 Total deposits $ 46,560,186 $ 42,695,696
Additional Information About Corporation's Deposits	The following table presents additional information about our deposits: September 30, December 31, Deposits from foreign sources (primarily Mexico) $ 1,069,964 $ 993,479 Non-interest-bearing public funds deposits 688,227 1,235,026 Interest-bearing public funds deposits 746,671 810,863 Total deposits not covered by deposit insurance 26,614,691 24,125,359 Time deposits not covered by deposit insurance 407,758 238,608

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Financial Instruments with Off-Balance-Sheet Risk	Financial instruments with off-balance-sheet risk were as follows: September 30, December 31, Commitments to extend credit $ 11,439,755 $ 10,420,142 Standby letters of credit 383,720 238,690 Deferred standby letter of credit fees 2,144 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 Nine Months Ended 2022 2021 2022 2021 Beginning balance $ 50,246 $ 48,596 $ 50,314 $ 44,152 Credit loss expense (benefit) 2,463 3,023 2,395 7,467 Ending balance $ 52,709 $ 51,619 $ 52,709 $ 51,619
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 Nine Months Ended 2022 2021 2022 2021 Amortization of lease right-of-use assets $ 8,389 $ 8,172 $ 24,703 $ 24,584 Short-term lease expense 536 384 1,639 1,118 Non-lease components (including taxes, insurance, common maintenance, etc.) 3,092 2,864 8,860 8,205 Total $ 12,017 $ 11,420 $ 35,202 $ 33,907

Capital and Regulatory Matters

Capital and Regulatory Matters (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 Plus Capital Conservation Buffer Required to be Considered Well- Capitalized (1) Capital Ratio Capital Ratio Capital Ratio September 30, 2022 Common Equity Tier 1 to Risk-Weighted Assets Cullen/Frost $ 3,606,527 12.74 % $ 1,981,042 7.00 % N/A N/A Frost Bank 3,595,393 12.71 1,979,976 7.00 1,838,550 6.50 % Tier 1 Capital to Risk-Weighted Assets Cullen/Frost 3,751,979 13.26 2,405,550 8.50 1,698,036 6.00 Frost Bank 3,595,393 12.71 2,404,257 8.50 2,262,830 8.00 Total Capital to Risk-Weighted Assets Cullen/Frost 4,187,120 14.80 2,971,562 10.50 2,830,059 10.00 Frost Bank 3,830,534 13.54 2,969,965 10.50 2,828,538 10.00 Leverage Ratio Cullen/Frost 3,751,979 7.09 2,117,091 4.00 N/A N/A Frost Bank 3,595,393 6.79 2,117,519 4.00 2,646,898 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 % N/A N/A 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 1,539,899 6.00 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 N/A N/A Frost Bank 3,261,532 6.80 1,917,679 4.00 2,397,099 5.00

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2022 and December 31, 2021. September 30, 2022 December 31, 2021 Notional Estimated Notional Estimated Derivatives designated as hedges of fair value: Financial institution counterparties: Loan/lease interest rate swaps – assets $ 1,679 $ 25 $ — $ — Loan/lease interest rate swaps – liabilities — — 2,426 (34) Non-hedging interest rate derivatives: Financial institution counterparties: Loan/lease interest rate swaps – assets 1,229,040 61,992 247,592 1,207 Loan/lease interest rate swaps – liabilities 126,112 (1,088) 928,756 (19,142) Loan/lease interest rate caps – assets 243,840 15,777 270,431 3,239 Customer counterparties: Loan/lease interest rate swaps – assets 67,780 1,104 928,756 39,864 Loan/lease interest rate swaps – liabilities 1,185,815 (82,228) 247,592 (2,846) Loan/lease interest rate caps – liabilities 243,840 (15,777) 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 September 30, 2022 were as follows: Weighted-Average Interest Interest Interest rate swaps: Fair value hedge loan/lease interest rate swaps 1.58 % 2.56 % Non-hedging interest rate swaps – financial institution counterparties 3.74 4.23 Non-hedging interest rate swaps – customer counterparties 4.21 3.73
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. September 30, 2022 December 31, 2021 Notional Notional Estimated Notional Estimated Financial institution counterparties: Oil – assets Barrels 4,467 $ 45,381 4,809 $ 14,721 Oil – liabilities Barrels 6,987 (55,645) 7,032 (73,594) Natural gas – assets MMBTUs 13,406 4,033 15,947 4,143 Natural gas – liabilities MMBTUs 20,489 (40,049) 29,446 (21,249) Customer counterparties: Oil – assets Barrels 7,006 56,366 7,046 74,437 Oil – liabilities Barrels 4,448 (44,674) 4,796 (14,294) Natural gas – assets MMBTUs 20,489 40,153 29,446 21,456 Natural gas – liabilities MMBTUs 13,406 (4,017) 15,947 (4,124)
Schedule of Foreign Exchange Contracts, Statement of Financial Position	The notional amounts and fair values of open foreign currency forward and option contracts were as follows: September 30, 2022 December 31, 2021 Notional Notional Estimated Notional Estimated Financial institution counterparties: Forward and option contracts – assets EUR 2,925 $ 1 1,900 $ 29 Forward and option contracts – assets CAD — — 658 — Forward and option contracts – liabilities EUR 2,925 (251) — — Customer counterparties: Forward and option contracts – assets EUR 2,925 251 — — Forward and option contracts – assets CAD — — 658 4 Forward and option contracts – liabilities EUR 2,925 (1) 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 Nine Months Ended 2022 2021 2022 2021 Commercial loan/lease interest rate swaps: Amount of gain (loss) included in interest income on loans $ 2 $ (21) $ (16) $ (74) Amount of (gain) loss included in other non-interest expense 1 3 6 8
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 Nine Months Ended 2022 2021 2022 2021 Non-hedging interest rate derivatives: Other non-interest income $ 140 $ 946 $ 1,171 $ 2,674 Other non-interest expense — — — (1) Non-hedging commodity derivatives: Other non-interest income 485 1,143 2,063 3,266 Non-hedging foreign currency derivatives: Other non-interest income — 4 63 34

Balance Sheet Offsetting (Table

Balance Sheet Offsetting (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2022 is presented in the following tables. Gross Amount Gross Amount Net Amount September 30, 2022 Financial assets: Derivatives: Loan/lease interest rate swaps and caps $ 77,794 $ — $ 77,794 Commodity swaps and options 49,414 — 49,414 Foreign currency forward contracts 1 — 1 Total derivatives 127,209 — 127,209 Resell agreements 12,150 — 12,150 Total $ 139,359 $ — $ 139,359 Financial liabilities: Derivatives: Loan/lease interest rate swaps and caps $ 1,088 $ — $ 1,088 Commodity swaps and options 95,694 — 95,694 Foreign currency forward contracts 251 — 251 Total derivatives 97,033 — 97,033 Repurchase agreements 2,082,739 — 2,082,739 Total $ 2,179,772 $ — $ 2,179,772 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 Gross Amount Net Amount 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 Financial Collateral Net September 30, 2022 Financial assets: Derivatives: Counterparty A $ 47 $ (47) $ — $ — Counterparty B 44,271 (35,853) (6,063) 2,355 Counterparty C 407 (251) — 156 Other counterparties 82,484 (53,163) (27,740) 1,581 Total derivatives 127,209 (89,314) (33,803) 4,092 Resell agreements 12,150 — (12,150) — Total $ 139,359 $ (89,314) $ (45,953) $ 4,092 Financial liabilities: Derivatives: Counterparty A $ 1,081 $ (47) $ (1,031) $ 3 Counterparty B 35,853 (35,853) — — Counterparty C 251 (251) — — Other counterparties 59,848 (53,163) (6,685) — Total derivatives 97,033 (89,314) (7,716) 3 Repurchase agreements 2,082,739 — (2,082,739) — Total $ 2,179,772 $ (89,314) $ (2,090,455) $ 3 Gross Amounts Not Offset Net Amount Financial Collateral Net 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 September 30, 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 September 30, 2022 Repurchase agreements: U.S. Treasury $ 1,348,705 $ — $ — $ — $ 1,348,705 Residential mortgage-backed securities 734,034 — — — 734,034 Total borrowings $ 2,082,739 $ — $ — $ — $ 2,082,739 Gross amount of recognized liabilities for repurchase agreements $ 2,082,739 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 $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 2022, there were 789,290 shares remaining available for grant for future stock-based compensation awards. Deferred Non-Vested Performance Stock Options Number Weighted- Number Weighted- Number Weighted- Number Weighted- Balance, January 1, 2022 56,301 $ 79.21 449,337 $ 93.05 202,460 $ 84.71 877,681 $ 69.02 Authorized — — — — — — — — Granted 5,382 133.67 4,676 130.30 — — — — Exercised/vested (16,022) 74.89 — — (25,180) 87.18 (191,410) 61.44 Forfeited/expired — — (5,603) 93.69 (16,058) 87.18 — — Balance, September 30, 2022 45,661 87.15 448,410 93.43 161,222 84.08 686,271 71.14
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 Nine Months Ended 2022 2021 2022 2021 New shares issued from available authorized shares — — — — Shares issued from available treasury stock 88,350 21,968 232,612 650,044 Proceeds from stock option exercises $ 5,270 $ 1,128 $ 11,760 $ 37,810
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 Nine Months Ended 2022 2021 2022 2021 Non-vested stock units $ 2,174 $ 1,559 $ 6,823 $ 5,210 Deferred stock units — — 720 700 Performance stock units 999 426 1,160 1,846 Total $ 3,173 $ 1,985 $ 8,703 $ 7,756 Income tax benefit $ 440 $ 281 $ 1,760 $ 1,162
Unrecognized Stock-Based Compensation Expense	Unrecognized stock-based compensation expense at September 30, 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 $ 11,704 Performance stock units 7,257 Total $ 18,961

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	9 Months Ended
	Sep. 30, 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 Nine Months Ended 2022 2021 2022 2021 Net income $ 169,760 $ 107,975 $ 387,976 $ 342,058 Less: Preferred stock dividends 1,668 1,668 5,006 5,488 Net income available to common shareholders 168,092 106,307 382,970 336,570 Less: Earnings allocated to participating securities 1,503 932 3,414 3,228 Net earnings allocated to common stock $ 166,589 $ 105,375 $ 379,556 $ 333,342 Distributed earnings allocated to common stock $ 55,820 $ 47,740 $ 151,963 $ 139,224 Undistributed earnings allocated to common stock 110,769 57,635 227,593 194,118 Net earnings allocated to common stock $ 166,589 $ 105,375 $ 379,556 $ 333,342 Weighted-average shares outstanding for basic earnings per common share 64,157,662 63,652,020 64,107,621 63,522,884 Dilutive effect of stock compensation 343,750 444,636 369,268 489,219 Weighted-average shares outstanding for diluted earnings per common share 64,501,412 64,096,656 64,476,889 64,012,103

Defined Benefit Plans (Tables)

Defined Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 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 Nine Months Ended 2022 2021 2022 2021 Expected return on plan assets, net of expenses $ (3,492) $ (3,210) $ (10,475) $ (9,630) Interest cost on projected benefit obligation 1,005 835 3,013 2,506 Net amortization and deferral 741 1,529 2,223 4,587 Net periodic expense (benefit) $ (1,746) $ (846) $ (5,239) $ (2,537)

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2022
Income Tax Disclosure [Abstract]
Income Tax Expense	Income tax expense was as follows: Three Months Ended Nine Months Ended 2022 2021 2022 2021 Current income tax expense (benefit) $ 28,684 $ 13,849 $ 64,389 $ 31,639 Deferred income tax expense (benefit) (974) (516) (3,378) 4,672 Income tax expense, as reported $ 27,710 $ 13,333 $ 61,011 $ 36,311 Effective tax rate 14.0 % 11.0 % 13.6 % 9.6 %

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	9 Months Ended
	Sep. 30, 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 Three Months Ended Before Tax Tax Expense, Net of Tax Before Tax Tax Expense, Net of Tax Securities available for sale and transferred securities: Change in net unrealized gain/loss during the period $ (829,324) $ (174,158) $ (655,166) $ (80,668) $ (16,941) $ (63,727) Change in net unrealized gain on securities transferred to held to maturity (174) (36) (138) (237) (49) (188) Reclassification adjustment for net (gains) losses included in net income — — — — — — Total securities available for sale and transferred securities (829,498) (174,194) (655,304) (80,905) (16,990) (63,915) 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) 741 156 585 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) $ (828,757) $ (174,038) $ (654,719) $ (79,376) $ (16,669) $ (62,707) Nine Months Ended Nine Months Ended Before Tax Tax Expense, Net of Tax Before Tax Tax Expense, Net of Tax Securities available for sale and transferred securities: Change in net unrealized gain/loss during the period $ (2,376,642) $ (499,095) $ (1,877,547) $ (209,779) $ (44,054) $ (165,725) Change in net unrealized gain on securities transferred to held to maturity (572) (120) (452) (741) (155) (586) Reclassification adjustment for net (gains) losses included in net income — — — — — — Total securities available for sale and transferred securities (2,377,214) (499,215) (1,877,999) (210,520) (44,209) (166,311) 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) 2,223 467 1,756 4,587 963 3,624 Total defined-benefit post-retirement benefit plans 2,223 467 1,756 4,587 963 3,624 Total other comprehensive income (loss) $ (2,374,991) $ (498,748) $ (1,876,243) $ (205,933) $ (43,246) $ (162,687)
Schedule of Accumulated Other Comprehensive Income (Loss)	Activity in accumulated other comprehensive income (loss), net of tax, was as follows: Securities Defined Accumulated Balance January 1, 2022 $ 380,209 $ (32,891) $ 347,318 Other comprehensive income (loss) before reclassifications (1,877,999) — (1,877,999) Reclassification of amounts included in net income — 1,756 1,756 Net other comprehensive income (loss) during period (1,877,999) 1,756 (1,876,243) Balance at September 30, 2022 $ (1,497,790) $ (31,135) $ (1,528,925) Balance January 1, 2021 $ 563,801 $ (50,831) $ 512,970 Other comprehensive income (loss) before reclassifications (166,311) — (166,311) Reclassification of amounts included in net income — 3,624 3,624 Net other comprehensive income (loss) during period (166,311) 3,624 (162,687) Balance at September 30, 2021 $ 397,490 $ (47,207) $ 350,283

Operating Segments (Tables)

Operating Segments (Tables)	9 Months Ended
	Sep. 30, 2022
Segment Reporting [Abstract]
Summary of Operating Results by Segment	Summarized operating results by segment were as follows: Banking Frost Wealth Non-Banks Consolidated Three months ended: September 30, 2022 Net interest income (expense) $ 356,513 $ 1,357 $ (2,323) $ 355,547 Credit loss expense (1) 1 — — Non-interest income 55,994 44,263 (436) 99,821 Non-interest expense 223,193 33,530 1,175 257,898 Income (loss) before income taxes 189,315 12,089 (3,934) 197,470 Income tax expense (benefit) 26,520 2,539 (1,349) 27,710 Net income (loss) 162,795 9,550 (2,585) 169,760 Preferred stock dividends — — 1,668 1,668 Net income (loss) available to common shareholders $ 162,795 $ 9,550 $ (4,253) $ 168,092 Revenues from (expenses to) external customers $ 412,507 $ 45,620 $ (2,759) $ 455,368 September 30, 2021 Net interest income (expense) $ 247,381 $ 536 $ (1,795) $ 246,122 Credit loss expense (benefit) (6) 6 — — Non-interest income 51,279 42,369 (459) 93,189 Non-interest expense 185,891 31,086 1,026 218,003 Income (loss) before income taxes 112,775 11,813 (3,280) 121,308 Income tax expense (benefit) 12,029 2,481 (1,177) 13,333 Net income (loss) 100,746 9,332 (2,103) 107,975 Preferred stock dividends — — 1,668 1,668 Net income (loss) available to common shareholders $ 100,746 $ 9,332 $ (3,771) $ 106,307 Revenues from (expenses to) external customers $ 298,660 $ 42,905 $ (2,254) $ 339,311 Nine months ended: September 30, 2022 Net interest income (expense) $ 895,818 $ 3,015 $ (6,007) $ 892,826 Credit loss expense (benefit) (1) 1 — — Non-interest income 170,097 130,546 (1,505) 299,138 Non-interest expense 640,775 97,598 4,604 742,977 Income (loss) before income taxes 425,141 35,962 (12,116) 448,987 Income tax expense (benefit) 57,355 7,552 (3,896) 61,011 Net income (loss) 367,786 28,410 (8,220) 387,976 Preferred stock dividends — — 5,006 5,006 Net income (loss) available to common shareholders $ 367,786 $ 28,410 $ (13,226) $ 382,970 Revenues from (expenses to) external customers $ 1,065,915 $ 133,561 $ (7,512) $ 1,191,964 September 30, 2021 Net interest income (expense) $ 748,036 $ 1,530 $ (5,407) $ 744,159 Credit loss expense 57 6 — 63 Non-interest income 154,003 124,512 (843) 277,672 Non-interest expense 548,151 91,037 4,211 643,399 Income (loss) before income taxes 353,831 34,999 (10,461) 378,369 Income tax expense (benefit) 32,811 7,350 (3,850) 36,311 Net income (loss) 321,020 27,649 (6,611) 342,058 Preferred stock dividends — — 5,488 5,488 Net income (loss) available to common shareholders $ 321,020 $ 27,649 $ (12,099) $ 336,570 Revenues from (expenses to) external customers $ 902,039 $ 126,042 $ (6,250) $ 1,021,831

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 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 September 30, 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 September 30, 2022 Securities available for sale: U.S. Treasury $ 5,022,617 $ — $ — $ 5,022,617 Residential mortgage-backed securities — 5,698,809 — 5,698,809 States and political subdivisions — 6,635,298 — 6,635,298 Other — 42,383 — 42,383 Trading account securities: U.S. Treasury 25,008 — — 25,008 Derivative assets: Interest rate swaps, caps and floors — 78,898 — 78,898 Commodity swaps and options — 145,933 — 145,933 Foreign currency forward contracts 252 — — 252 Derivative liabilities: Interest rate swaps, caps and floors — 99,093 — 99,093 Commodity swaps and options — 144,385 — 144,385 Foreign currency forward contracts 252 — — 252 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. Nine Months Ended Nine Months Ended Level 2 Level 3 Level 2 Level 3 Carrying value before allocations $ 7,999 $ 2,087 $ 3,329 $ 15,274 Specific (allocations) reversals of prior allocations (1,742) 4,881 (336) (4,791) Fair value $ 6,257 $ 6,968 $ 2,993 $ 10,483
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: September 30, 2022 December 31, 2021 Carrying Estimated Carrying Estimated Financial assets: Level 2 inputs: Cash and cash equivalents $ 13,632,698 $ 13,632,698 $ 16,583,000 $ 16,583,000 Securities held to maturity 2,174,084 1,917,287 1,749,179 1,809,143 Cash surrender value of life insurance policies 190,368 190,368 190,139 190,139 Accrued interest receivable 169,540 169,540 179,111 179,111 Level 3 inputs: Loans, net 16,716,314 16,163,170 16,087,731 16,079,454 Financial liabilities: Level 2 inputs: Deposits 46,560,186 46,538,352 42,695,696 41,343,426 Federal funds purchased 26,200 26,200 25,925 25,925 Repurchase agreements 2,082,739 2,082,739 2,740,799 2,740,799 Junior subordinated deferrable interest debentures 123,055 123,712 123,011 123,712 Subordinated notes 99,295 96,926 99,178 111,430 Accrued interest payable 9,545 9,545 3,026 3,026

Significant Accounting Polici_4

Significant Accounting Policies - Additional Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Cash paid for interest	$ 71,848	$ 23,722
Cash paid for income taxes	78,500	28,043
Unsettled securities transactions	470,813	600,874
Loans foreclosed and transferred to other real estate owned and foreclosed assets	0	3,464
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities	23,959	4,045
Treasury stock issued to 401(k) stock purchase plan	$ 0	$ 1,749

Securities - Additional Informa

Securities - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Schedule Of Marketable Securities [Line Items]
Carrying value of pledged securities held to maturity	$ 2,174,084		$ 2,174,084		$ 1,749,179
AOCI, Debt Securities, Available-for-sale, Adjustment, Pre Tax	2,000		2,000		2,500
Net unamortized unrealized gain on transferred securities included in accumulated other comprehensive income, net of tax	$ 1,600		$ 1,600		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	75.10%		75.10%
Carrying value of pledged securities, available-for-sale	$ 17,399,107		$ 17,399,107		13,924,628
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0		0
Proceeds from Sale of Held-to-maturity Securities	0	$ 0	0	$ 0
Proceeds from Sale of Debt Securities, Available-for-sale	0	$ 0	0	$ 0
Held-to-maturity Securities [Member]
Schedule Of Marketable Securities [Line Items]
Accrued interest receivable	11,500		11,500		18,400
Held-to-maturity Securities [Member] | Collateralized Securities
Schedule Of Marketable Securities [Line Items]
Carrying value of pledged securities held to maturity	271,600		271,600		642,300
Available-for-sale Securities [Member]
Schedule Of Marketable Securities [Line Items]
Accrued interest receivable	99,700		99,700		120,500
Available-for-sale Securities [Member] | Collateralized Securities
Schedule Of Marketable Securities [Line Items]
Carrying value of pledged securities, available-for-sale	$ 4,900,000		$ 4,900,000		$ 5,800,000

Securities Securities - Amortiz

Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	$ 2,174,242	$ 1,749,337
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	90	59,907
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	257,045	101
Debt Securities, Held-to-maturity, Fair Value	1,917,287	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 September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	526,397	527,264
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	18,766
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	68,024	0
Debt Securities, Held-to-maturity, Fair Value	458,373	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 September 30, 2022 and $158 at December 31, 2021	526,397	527,264
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	1,646,345	1,220,573
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	90	41,141
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	188,964	101
Debt Securities, Held-to-maturity, Fair Value	1,457,471	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 September 30, 2022 and $158 at December 31, 2021	1,646,187	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	57	0
Debt Securities, Held-to-maturity, Fair Value	1,443	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 September 30, 2022 and $158 at December 31, 2021	$ 1,500	$ 1,500

Securities Securities - Moody's

Securities Securities - Moody's and/or Standard & Poor's Bond Rating (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 2,174,242	$ 1,749,337
US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,646,345	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	1,457,704	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	188,641	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	408,821	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	220,180	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	188,641	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	1,116,482	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	1,116,482	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	121,042	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	121,042	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

Securities Securities - Allowan

Securities Securities - Allowance for Credit Losses on Held to Maturity Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Securities, held-to-maturity, allowance for credit loss	$ 158		$ 158			$ 158
Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities, held-to-maturity, allowance for credit loss	158	$ 158	158	$ 158	$ 158	$ 158	$ 158	$ 160
Credit loss expense (benefit)	$ 0	$ 0	$ 0	$ (2)

Securities Securities - Amort_2

Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 19,297,009	$ 13,445,888
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2,688	518,805
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,900,590	40,065
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	17,399,107	13,924,628
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,447,478	2,165,702
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	23,333
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	424,861	9,602
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	5,022,617	2,179,433
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	6,685,418	4,059,692
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,293	31,662
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	987,902	25,089
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	5,698,809	4,066,265
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	7,121,730	7,178,135
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,395	463,810
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	487,827	5,374
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	6,635,298	7,636,571
Other Investments [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	42,383	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	$ 42,383	$ 42,359

Securities - Securities Availab

Securities - Securities Available for Sale, with Unrealized Losses Segregated by Length of Impairment (Detail) - USD ($) $ in Thousands	Sep. 30, 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	$ 14,653,234
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1,449,969
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,819,775
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	450,621
Debt Securities, Available-for-sale, Unrealized Loss Position	16,473,009
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,900,590	$ 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	4,429,609
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	323,346
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	593,008
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	101,515
Debt Securities, Available-for-sale, Unrealized Loss Position	5,022,617
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	424,861	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	4,280,074
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	713,685
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,032,311
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	274,217
Debt Securities, Available-for-sale, Unrealized Loss Position	5,312,385
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	987,902	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	5,943,551
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	412,938
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	194,456
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	74,889
Debt Securities, Available-for-sale, Unrealized Loss Position	6,138,007
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 487,827	$ 5,374

Securities - Amortized Cost and

Securities - Amortized Cost and Estimated Fair Value of Securities, Excluding Trading Securities, Presented by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	$ 121,042
Held to Maturity, Due after one year through five years, Amortized Cost	31,034
Held to Maturity, Due after five years through ten years, Amortized Cost	524,201
Held to Maturity, Due after ten years, Amortized Cost	1,497,965
Held to Maturity, Amortized Cost	2,174,242	$ 1,749,337
Held to Maturity, Due in one year or less, Estimated Fair Value	120,786
Held to Maturity, Due after one year through five years, Estimated Fair Value	30,805
Held to Maturity, Due after five years through ten years, Estimated Fair Value	458,364
Held to Maturity, Due after ten years, Estimated Fair Value	1,307,332
Held to Maturity, Estimated Fair Value	1,917,287	1,809,143
Available-for-sale Securities, Due in one year or less, Amortized Cost	250,345
Available for Sale, Due after one year through five years, Amortized Cost	5,301,345
Available for Sale, Due after five years through ten years, Amortized Cost	2,395,444
Available for Sale, Due after ten years, Amortized Cost	11,307,492
Debt Securities, Available-for-sale, Amortized Cost	19,297,009	13,445,888
Available for Sale, Due in one year or less, Estimated Fair Value	250,902
Available for Sale, Due after one year through five years, Estimated Fair Value	5,119,877
Available for Sale, Due after five years through ten years, Estimated Fair Value	2,144,310
Available for Sale, Due after ten years, Estimated Fair Value	9,841,635
Securities available for sale, at estimated fair value	17,399,107	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	3,821,606
Available for Sale, Due after five years through ten years, Amortized Cost	1,433,912
Available for Sale, Due after ten years, Amortized Cost	191,960
Debt Securities, Available-for-sale, Amortized Cost	5,447,478	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	3,648,015
Available for Sale, Due after five years through ten years, Estimated Fair Value	1,232,969
Available for Sale, Due after ten years, Estimated Fair Value	141,633
Securities available for sale, at estimated fair value	5,022,617	2,179,433
Residential Mortgage Backed Securities [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	0
Held to Maturity, Due after five years through ten years, Amortized Cost	514,321
Held to Maturity, Due after ten years, Amortized Cost	12,076
Held to Maturity, Amortized Cost	526,397	527,264
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	0
Held to Maturity, Due after five years through ten years, Estimated Fair Value	448,514
Held to Maturity, Due after ten years, Estimated Fair Value	9,859
Held to Maturity, Estimated Fair Value	458,373	546,030
Available-for-sale Securities, Due in one year or less, Amortized Cost	28
Available for Sale, Due after one year through five years, Amortized Cost	9,355
Available for Sale, Due after five years through ten years, Amortized Cost	17,253
Available for Sale, Due after ten years, Amortized Cost	6,658,782
Debt Securities, Available-for-sale, Amortized Cost	6,685,418	4,059,692
Available for Sale, Due in one year or less, Estimated Fair Value	27
Available for Sale, Due after one year through five years, Estimated Fair Value	9,130
Available for Sale, Due after five years through ten years, Estimated Fair Value	17,167
Available for Sale, Due after ten years, Estimated Fair Value	5,672,485
Securities available for sale, at estimated fair value	5,698,809	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	121,042
Held to Maturity, Due after one year through five years, Amortized Cost	29,534
Held to Maturity, Due after five years through ten years, Amortized Cost	9,880
Held to Maturity, Due after ten years, Amortized Cost	1,485,889
Held to Maturity, Amortized Cost	1,646,345	1,220,573
Held to Maturity, Due in one year or less, Estimated Fair Value	120,786
Held to Maturity, Due after one year through five years, Estimated Fair Value	29,362
Held to Maturity, Due after five years through ten years, Estimated Fair Value	9,850
Held to Maturity, Due after ten years, Estimated Fair Value	1,297,473
Held to Maturity, Estimated Fair Value	1,457,471	1,261,613
Available-for-sale Securities, Due in one year or less, Amortized Cost	250,317
Available for Sale, Due after one year through five years, Amortized Cost	1,470,384
Available for Sale, Due after five years through ten years, Amortized Cost	944,279
Available for Sale, Due after ten years, Amortized Cost	4,456,750
Debt Securities, Available-for-sale, Amortized Cost	7,121,730	7,178,135
Available for Sale, Due in one year or less, Estimated Fair Value	250,875
Available for Sale, Due after one year through five years, Estimated Fair Value	1,462,732
Available for Sale, Due after five years through ten years, Estimated Fair Value	894,174
Available for Sale, Due after ten years, Estimated Fair Value	4,027,517
Securities available for sale, at estimated fair value	6,635,298	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	1,443
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	1,443	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	42,383	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	$ 42,383	$ 42,359

Securities Securities - Premium

Securities Securities - Premium Amortization and Discount Accretion Included in Income on Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Premium amortization	$ (27,165)	$ (30,240)	$ (84,278)	$ (92,016)
Discount accretion	4,062	657	7,950	1,999
Net (premium amortization) discount accretion	$ (23,103)	$ (29,583)	$ (76,328)	$ (90,017)

Securities - Trading Account Se

Securities - Trading Account Securities, at Estimated Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	$ 25,008	$ 25,162
U.S. Treasury [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	25,008	24,237
States and political subdivisions [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	$ 0	$ 925

Securities - Net Gains and Loss

Securities - Net Gains and Losses on Trading Account Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Investments, Debt and Equity Securities [Abstract]
Net gain on sales transactions	$ 1,110	$ 314	$ 2,462	$ 716
Net mark-to-market gains (losses)	9	(2)	(235)	(71)
Net gain (loss) on trading account securities	$ 1,119	$ 312	$ 2,227	$ 645

Loans - Additional Information

Loans - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jun. 30, 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%		0%
Maximum percentage loan related to single industry	10%		10%
U.S. dollar denominated loans and commitments to borrowers in Mexico	$ 0		$ 0			$ 0
Loans and Leases Receivable, Related Parties	$ 356,400		$ 356,400			$ 350,500
Texas Leading Index economic condition indicator	130.3		130.3			135.9
Financing Receivable, Allowance for Credit Loss	$ 234,315		$ 234,315			$ 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	5.40%		5.40%
Percentage of total energy loans to total loans excluding PPP Loans	5.40%		5.40%
Financing Receivable, Allowance for Credit Loss	$ 18,851	$ 20,449	$ 18,851	$ 20,449	$ 16,267	17,217	$ 28,010	$ 39,553
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	0	0	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	372	$ 474	1,200	$ 1,400
Commitments to Extend Credit [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	1,100,000		1,100,000
Standby Letters of Credit [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	117,000		117,000
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable	$ 48,700		$ 48,700			$ 40,000

Loans - Loans (Detail)

Loans - Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 16,950,629	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	5,531,820	5,364,954
Energy Production [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	701,975	878,436
Energy Service [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	127,065	105,901
Energy Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	89,085	93,455
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	918,125	1,077,792
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	51,048	428,882
Commercial mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	6,149,504	5,867,062
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	1,557,415	1,304,271
Commercial land loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	524,423	405,277
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	8,231,342	7,576,610
Home Equity Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	401,234	324,157
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	661,618	519,098
Other consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	652,884	567,535
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	1,715,736	1,410,790
Real Estate Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	9,947,078	8,987,400
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 502,558	$ 477,369

Loans - Non-Accrual Loans, Segr

Loans - Non-Accrual Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 29,904	$ 53,713
Non-accrual with no credit loss allowance	14,911	27,202
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	7,267	22,582
Non-accrual with no credit loss allowance	4,425	4,701
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	16,134	14,433
Non-accrual with no credit loss allowance	7,277	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	5,489	15,297
Non-accrual with no credit loss allowance	2,497	13,817
Construction Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	0	948
Non-accrual with no credit loss allowance	0	0
Total consumer real estate loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	1,014	440
Non-accrual with no credit loss allowance	712	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

Loans Loans - Non-Accrual Loans

Loans Loans - Non-Accrual Loans, Segregated by Class of Loans and Year of Origination (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 29,904	$ 53,713
Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	6,237
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,493
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,137
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,862
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,729
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2,097
Financing Receivable, Revolving	8,213
Financing Receivable, Revolving, Converted to Term Loan	3,136
Commercial Portfolio Segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,251,173
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	739,635
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	544,428
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	261,580
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	152,945
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	211,871
Financing Receivable, Revolving	2,305,283
Non-accrual loans	7,267	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	85
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,065
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,245
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,439
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	234
Financing Receivable, Revolving	467
Financing Receivable, Revolving, Converted to Term Loan	732
Commercial and Industrial Total Energy Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	335,500
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	105,443
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	5,728
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	11,366
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4,235
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,297
Financing Receivable, Revolving	404,598
Non-accrual loans	16,134	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	5,154
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	72
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,394
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	15
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	7,746
Financing Receivable, Revolving, Converted to Term Loan	1,753
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	1,533,485
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,608,671
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,061,879
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	860,710
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	422,630
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	969,306
Financing Receivable, Revolving	109,368
Non-accrual loans	5,489	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	1,083
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,408
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	223
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	275
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,500
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	0
Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	504,958
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	571,022
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	164,362
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	49,302
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	490
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,762
Financing Receivable, Revolving	261,105
Non-accrual loans	0	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	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
Total consumer real estate loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	1,014	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	363
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	651
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

Loans - Age Analysis of Past Du

Loans - Age Analysis of Past Due Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Total loans	$ 16,950,629	$ 16,336,397
Accruing Loans 90 or More Days Past Due	14,347
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total loans	5,531,820	5,364,954
Accruing Loans 90 or More Days Past Due	2,443
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	918,125	1,077,792
Accruing Loans 90 or More Days Past Due	0
Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Total loans	51,048	428,882
Accruing Loans 90 or More Days Past Due	7,879
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	6,673,927	6,272,339
Accruing Loans 90 or More Days Past Due	1,731
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	1,557,415	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	1,715,736	1,410,790
Accruing Loans 90 or More Days Past Due	1,803
Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Total loans	502,558	$ 477,369
Accruing Loans 90 or More Days Past Due	491
Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	76,985
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	26,481
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	2,211
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	13,841
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	20,434
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	1,238
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	7,169
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	5,611
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	25,195
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	4,629
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	7,745
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	7,879
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	2,341
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	2,110
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	491
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	102,180
Financial Asset, Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	31,110
Financial Asset, Past Due | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,956
Financial Asset, Past Due | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	21,720
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	22,775
Financial Asset, Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,238
Financial Asset, Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	9,279
Financial Asset, Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,102
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	16,848,449
Financial Asset, Not Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,500,710
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	908,169
Financial Asset, Not Past Due | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	29,328
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	6,651,152
Financial Asset, Not Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,556,177
Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,706,457
Financial Asset, Not Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 496,456

Loans - Troubled Debt Restructu

Loans - Troubled Debt Restructuring (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified as troubled debt restructurings	$ 1,155	$ 7,017
Balance at period end	1,083	6,678
Commercial Portfolio Segment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified as troubled debt restructurings	0	1,312
Balance at period end	0	1,237
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified as troubled debt restructurings	0	3,817
Balance at period end	0	3,566
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans modified as troubled debt restructurings	1,155	1,888
Balance at period end	$ 1,083	$ 1,875

Loans Loans - Restructured Loan

Loans Loans - Restructured Loans Past Due in Excess of 90 Days on Financing Receivables (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($) Item	Sep. 30, 2021 USD ($) Item
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number Of Restructured Loans Past Due In Excess of 90 Days At Period-End | Item	0	1
Dollar amount of previously restructured loans past due	$ 0	$ 306
Restructured loans on non-accrual status at period end	1,083	5,072
Charge-offs of restructured loans recognized in connection with restructuring	0	0
Charge-offs of restructured loans recognized on previously restructured loans	723	1,433
Proceeds from sale of restructured loans	$ 1,070	$ 0

Loans Loans - Weighted Average

Loans Loans - Weighted Average Risk Grade for All Commercial Loans by Class and Year of Origination (Details) $ in Thousands	Sep. 30, 2022 USD ($) Grade	Dec. 31, 2021 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,950,629	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,251,173
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	739,635
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	544,428
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	261,580
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	152,945
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	211,871
Financing Receivable, Revolving	2,305,283
Loans and Leases Receivable, Net of Deferred Income	$ 5,531,820	$ 5,364,954
Weighted Average Risk Grade For Loans | Grade	6.41	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	$ 335,500
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	105,443
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	5,728
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	11,366
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4,235
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,297
Financing Receivable, Revolving	404,598
Loans and Leases Receivable, Net of Deferred Income	$ 918,125	$ 1,077,792
Weighted Average Risk Grade For Loans | Grade	5.86	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	$ 1,533,485
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,608,671
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,061,879
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	860,710
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	422,630
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	969,306
Financing Receivable, Revolving	109,368
Loans and Leases Receivable, Net of Deferred Income	$ 6,673,927	$ 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	$ 504,958
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	571,022
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	164,362
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	49,302
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	490
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,762
Financing Receivable, Revolving	261,105
Loans and Leases Receivable, Net of Deferred Income	$ 1,557,415	$ 1,304,271
Weighted Average Risk Grade For Loans | Grade	6.99	7.06
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,038,443
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,179,693
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,226,241
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	910,012
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	423,120
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	971,068
Financing Receivable, Revolving	370,473
Loans and Leases Receivable, Net of Deferred Income	$ 8,231,342	$ 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	$ 1,214,942
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	706,035
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	529,894
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	242,581
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	136,161
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	199,629
Financing Receivable, Revolving	2,180,437
Loans and Leases Receivable, Net of Deferred Income	$ 5,256,767	$ 5,063,847
Weighted Average Risk Grade For Loans | Grade	6.25	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	$ 319,910
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	105,110
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	5,238
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	5,674
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,346
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,146
Financing Receivable, Revolving	386,836
Loans and Leases Receivable, Net of Deferred Income	$ 874,383	$ 1,008,370
Weighted Average Risk Grade For Loans | Grade	5.61	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	$ 1,434,936
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,556,836
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	936,889
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	731,589
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	361,215
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	868,933
Financing Receivable, Revolving	101,817
Loans and Leases Receivable, Net of Deferred Income	$ 6,097,383	$ 5,574,922
Weighted Average Risk Grade For Loans | Grade	6.91	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	$ 464,837
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	568,694
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	162,262
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	35,986
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	490
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,762
Financing Receivable, Revolving	243,723
Loans and Leases Receivable, Net of Deferred Income	$ 1,482,168	$ 1,262,200
Weighted Average Risk Grade For Loans | Grade	6.85	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	$ 34,065
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	28,895
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,211
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6,909
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	12,436
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	9,923
Financing Receivable, Revolving	94,984
Loans and Leases Receivable, Net of Deferred Income	$ 204,556	$ 187,870
Weighted Average Risk Grade For Loans | Grade	9	9
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	$ 1,722
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	147
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	245
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	659
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	829
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	10,016
Loans and Leases Receivable, Net of Deferred Income	$ 13,653	$ 36,622
Weighted Average Risk Grade For Loans | Grade	9	9
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	$ 51,425
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	20,259
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	109,106
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	79,833
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	24,749
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	54,595
Financing Receivable, Revolving	4,558
Loans and Leases Receivable, Net of Deferred Income	$ 346,659	$ 321,533
Weighted Average Risk Grade For Loans | Grade	9	9
Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 11,270
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,253
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	2,100
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	17,382
Loans and Leases Receivable, Net of Deferred Income	$ 33,005	$ 41,123
Weighted Average Risk Grade For Loans | Grade	9	9
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
Risk Grade Ten [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 2,131
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	636
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	814
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,513
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,518
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	143
Financing Receivable, Revolving	21,207
Loans and Leases Receivable, Net of Deferred Income	$ 33,169	$ 59,137
Weighted Average Risk Grade For Loans | Grade	10	10
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	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	456
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	226
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 729	$ 1,773
Weighted Average Risk Grade For Loans | Grade	10	10
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	$ 33,233
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	14,484
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	11,364
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	42,672
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	29,990
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,012
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 137,755	$ 269,447
Weighted Average Risk Grade For Loans | Grade	10	10
Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 28,851
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	75
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	$ 28,926	$ 0
Weighted Average Risk Grade For Loans | Grade	10	10
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
Risk Grade Eleven [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 35
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	3,984
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	6,444
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,332
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,391
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,942
Financing Receivable, Revolving	8,188
Loans and Leases Receivable, Net of Deferred Income	$ 30,061	$ 31,518
Weighted Average Risk Grade For Loans | Grade	11	11
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	$ 8,714
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	186
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	173
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,183
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	819
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	151
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 13,226	$ 16,594
Weighted Average Risk Grade For Loans | Grade	11	11
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	$ 12,808
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	14,684
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,520
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	6,393
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	6,401
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	38,266
Financing Receivable, Revolving	2,993
Loans and Leases Receivable, Net of Deferred Income	$ 86,641	$ 91,140
Weighted Average Risk Grade For Loans | Grade	11	11
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	13,316
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	$ 13,316	$ 0
Weighted Average Risk Grade For Loans | Grade	11	11
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
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	85
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	837
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,975
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,419
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	234
Financing Receivable, Revolving	467
Loans and Leases Receivable, Net of Deferred Income	$ 6,453	$ 12,535
Weighted Average Risk Grade For Loans | Grade	12	12
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	$ 4,104
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	72
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,394
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	15
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	4,571
Loans and Leases Receivable, Net of Deferred Income	$ 10,459	$ 8,953
Weighted Average Risk Grade For Loans | Grade	12	12
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	$ 613
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,082
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	223
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	275
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,500
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 4,693	$ 15,097
Weighted Average Risk Grade For Loans | Grade	12	12
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	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	$ 748
Weighted Average Risk Grade For Loans | Grade	12	12
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
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	228
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	270
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	20
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 814	$ 10,047
Weighted Average Risk Grade For Loans | Grade	13	13
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	$ 1,050
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	3,175
Loans and Leases Receivable, Net of Deferred Income	$ 5,675	$ 5,480
Weighted Average Risk Grade For Loans | Grade	13	13
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	$ 470
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	$ 796	$ 200
Weighted Average Risk Grade For Loans | Grade	13	13
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	13
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
Revolving Credit Facility [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.25
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	5.40
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	7.26
Revolving Credit Facility [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.36
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	6.63
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	$ 64,905
Weighted Average Risk Grade For Loans | Grade	7.57
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	$ 46,958
Weighted Average Risk Grade For Loans | Grade	6.46
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	$ 107,878
Weighted Average Risk Grade For Loans | Grade	6.45
Revolving Loans Converted to Term [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 4,414
Weighted Average Risk Grade For Loans | Grade	5.01
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	$ 112,292
Weighted Average Risk Grade For Loans | Grade	6.39
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	$ 47,088
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	45,123
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	105,168
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	4,414
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	11,133
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	35
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	2,134
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	2,207
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	47
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	3,745
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	576
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	436
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	303
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	0
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	296
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	1,450
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	6.44
2022 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.22
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	7.11
2022 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.11
2022 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.11
2021 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.05
2021 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.64
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	7.19
2021 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.21
2021 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.20
2020 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.04
2020 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.67
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	7.27
2020 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.55
2020 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.17
2019 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.66
2019 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.81
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	7.20
2019 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.08
2019 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.24
2018 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.92
2018 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	8.52
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	7.35
2018 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6
2018 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.35
Prior Years [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.73
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	6.70
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	6.90
Prior Years [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.76
Prior Years [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.90

Loans - Weighted Average Risk G

Loans - Weighted Average Risk Grades for All Commercial Loans by Class (Detail) $ in Thousands	Sep. 30, 2022 USD ($) Grade	Dec. 31, 2021 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,950,629	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.41	6.22
Loans and Leases Receivable, Net of Deferred Income	$ 5,531,820	$ 5,364,954
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	5.86	6.06
Loans and Leases Receivable, Net of Deferred Income	$ 918,125	$ 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	$ 6,673,927	$ 6,272,339
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.99	7.06
Loans and Leases Receivable, Net of Deferred Income	$ 1,557,415	$ 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	$ 8,231,342	$ 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	6.25	6.01
Loans and Leases Receivable, Net of Deferred Income	$ 5,256,767	$ 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	5.61	5.78
Loans and Leases Receivable, Net of Deferred Income	$ 874,383	$ 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	6.91	6.91
Loans and Leases Receivable, Net of Deferred Income	$ 6,097,383	$ 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	6.85	6.99
Loans and Leases Receivable, Net of Deferred Income	$ 1,482,168	$ 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	9
Loans and Leases Receivable, Net of Deferred Income	$ 204,556	$ 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	9
Loans and Leases Receivable, Net of Deferred Income	$ 13,653	$ 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	9
Loans and Leases Receivable, Net of Deferred Income	$ 346,659	$ 321,533
Risk Grade Nine [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	9	9
Loans and Leases Receivable, Net of Deferred Income	$ 33,005	$ 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
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	10
Loans and Leases Receivable, Net of Deferred Income	$ 33,169	$ 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	10
Loans and Leases Receivable, Net of Deferred Income	$ 729	$ 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	10
Loans and Leases Receivable, Net of Deferred Income	$ 137,755	$ 269,447
Risk Grade Ten [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	10	10
Loans and Leases Receivable, Net of Deferred Income	$ 28,926	$ 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
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	11
Loans and Leases Receivable, Net of Deferred Income	$ 30,061	$ 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	11
Loans and Leases Receivable, Net of Deferred Income	$ 13,226	$ 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	11
Loans and Leases Receivable, Net of Deferred Income	$ 86,641	$ 91,140
Risk Grade Eleven [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	11	11
Loans and Leases Receivable, Net of Deferred Income	$ 13,316	$ 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
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	12
Loans and Leases Receivable, Net of Deferred Income	$ 6,453	$ 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	12
Loans and Leases Receivable, Net of Deferred Income	$ 10,459	$ 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	12
Loans and Leases Receivable, Net of Deferred Income	$ 4,693	$ 15,097
Risk Grade Twelve [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	12	12
Loans and Leases Receivable, Net of Deferred Income	$ 0	$ 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
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	13
Loans and Leases Receivable, Net of Deferred Income	$ 814	$ 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	13
Loans and Leases Receivable, Net of Deferred Income	$ 5,675	$ 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	13
Loans and Leases Receivable, Net of Deferred Income	$ 796	$ 200
Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	13	13
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
Loans and Leases Receivable, Net of Deferred Income		$ 400

Loans Loans - Age Analysis of P

Loans Loans - Age Analysis of Past Due Consumer Loans,Segregated by Class and Year of Origination (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,950,629	$ 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	1,715,736	1,410,790
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	502,558	$ 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	76,985
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	7,169
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	5,611
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	25,195
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	2,110
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	491
Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	102,180
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	9,279
Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,102
Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	16,848,449
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	1,706,457
Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	496,456
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	651,057
Revolving Credit Facility [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	388,323
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	1,549
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	218
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	208
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	1
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	1,757
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	219
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	649,300
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	388,104
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	10,584
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	24,437
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	1,602
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	2,128
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	230
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	39
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	1,832
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	2,167
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	8,752
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	22,270
2022 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	283,521
2022 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	48,981
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	90
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	1,985
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	435
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	90
2022 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,420
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	283,431
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	46,561
2021 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	318,588
2021 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	25,122
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	726
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	245
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	0
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	726
2021 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	245
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	317,862
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	24,877
2020 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	202,034
2020 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	8,920
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	689
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	935
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	64
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	753
2020 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	935
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	201,281
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	7,985
2019 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	75,699
2019 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	3,495
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	503
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	51
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	341
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	16
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	844
2019 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	67
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	74,855
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	3,428
2018 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	41,702
2018 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,505
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	405
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	6
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	151
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	556
2018 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	6
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	41,146
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	1,499
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	132,551
Prior Years [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,775
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	1,605
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	43
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	1,116
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	0
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	2,721
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	43
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	129,830
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	$ 1,732

Loans Loans - Revolving Loans C

Loans Loans - Revolving Loans Converted to Term (Details) - Revolving Loans Converted to Term [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	$ 6,613	$ 71,929	$ 49,472	$ 142,704
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	2,368	12,009	22,579	39,551
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	1,582	52,055	1,806	57,871
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	0	6,012	10,759	37,093
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	0	0	4,414	0
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	700	330	2,223	1,172
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	$ 1,963	$ 1,523	$ 7,691	$ 7,017

Loans Loans - Allowance for C_2

Loans Loans - Allowance for Credit Loss By Loan Class Calculated in Accordance With CECL Methodology (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 234,315		$ 248,666
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	98,830	$ 87,270	72,091	$ 63,766	$ 65,271	$ 73,843
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	18,851	16,267	17,217	20,449	28,010	39,553
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	100,607	117,106	144,936	152,054	147,993	134,892
Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	8,035	6,854	6,585	6,029	6,154	7,926
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	7,992	12,135	7,837	7,852	7,860	6,963
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	234,315	$ 239,632	248,666	$ 250,150	$ 255,288	$ 263,177
Modeled Expected Credit Losses [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	103,942		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	57,625		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	8,657		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	24,404		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	7,797		6,484
Modeled Expected Credit Losses [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,459		6,397
Q-factor adjustments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	121,446		149,348
Q-factor adjustments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	39,931		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	4,519		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	74,307		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	156		65
Q-factor adjustments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	2,533		1,440
Specific Valuation Allowances [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	8,927		16,452
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	1,274		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	5,675		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	1,896		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	82		36
Specific Valuation Allowances [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 0		$ 0

Loans - Activity in the Allowan

Loans - Activity in the Allowance for Credit Losses on Loans by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			$ 248,666
Ending balance	$ 234,315		234,315
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	87,270	$ 65,271	72,091	$ 73,843
Credit loss, expense (reversal)	10,844	(1,020)	29,347	(8,886)
Charge-offs	(572)	(1,611)	(5,918)	(4,485)
Recoveries	1,288	1,126	3,310	3,294
Net charge-offs	716	(485)	(2,608)	(1,191)
Ending balance	98,830	63,766	98,830	63,766
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	16,267	28,010	17,217	39,553
Credit loss, expense (reversal)	2,491	(7,720)	874	(19,048)
Charge-offs	0	0	(371)	(1,433)
Recoveries	93	159	1,131	1,377
Net charge-offs	93	159	760	(56)
Ending balance	18,851	20,449	18,851	20,449
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	117,106	147,993	144,936	134,892
Credit loss, expense (reversal)	(16,522)	4,007	(44,363)	16,583
Charge-offs	0	0	(702)	(137)
Recoveries	23	54	736	716
Net charge-offs	23	54	34	579
Ending balance	100,607	152,054	100,607	152,054
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	6,854	6,154	6,585	7,926
Credit loss, expense (reversal)	940	(982)	1,497	(3,093)
Charge-offs	(68)	0	(430)	(672)
Recoveries	309	857	383	1,868
Net charge-offs	241	857	(47)	1,196
Ending balance	8,035	6,029	8,035	6,029
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	12,135	7,860	7,837	6,963
Credit loss, expense (reversal)	(216)	2,692	10,250	7,042
Charge-offs	(6,549)	(5,073)	(17,642)	(13,015)
Recoveries	2,622	2,373	7,547	6,862
Net charge-offs	(3,927)	(2,700)	(10,095)	(6,153)
Ending balance	7,992	7,852	7,992	7,852
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	239,632	255,288	248,666	263,177
Credit loss, expense (reversal)	(2,463)	(3,023)	(2,395)	(7,402)
Charge-offs	(7,189)	(6,684)	(25,063)	(19,742)
Recoveries	4,335	4,569	13,107	14,117
Net charge-offs	(2,854)	(2,115)	(11,956)	(5,625)
Ending balance	$ 234,315	$ 250,150	$ 234,315	$ 250,150

Loans - Investment in Loans Rel

Loans - Investment in Loans Related to Allowance for Loan Losses by Portfolio Segment Disaggregated Based on Impairment Methodology (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 16,950,629	$ 16,336,397
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,531,820	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	918,125	1,077,792
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	51,048	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	6,673,927	6,272,339
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,557,415	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	1,715,736	1,410,790
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	502,558	477,369
Specific Valuation Allowances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	8,927	16,452
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	1,274	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	5,675	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	1,896	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	82	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	45,326	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	8,655	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	15,947	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	19,790	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	934	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

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Schedule of Goodwill (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 654,952	$ 654,952

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 486	$ 866
Core deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	395	718
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 91	$ 148

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Estimated Aggregate Future Amortization Expense for Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2022	$ 101
2023	282
2024	87
2025	11
2026	5
Future Amortization Expense, Total	$ 486	$ 866

Deposits - Schedule of Deposits

Deposits - Schedule of Deposits (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Deposit [Line Items]
Non-interest-bearing demand deposits	$ 18,565,820	$ 18,423,018
Interest-bearing Domestic Deposit, Savings	12,399,351	11,930,959
Interest-bearing Domestic Deposit, Money Market	13,939,882	11,228,815
Interest-bearing Domestic Deposit, Time Deposits	1,655,133	1,112,904
Total interest-bearing deposit	27,994,366	24,272,678
Total deposits	$ 46,560,186	$ 42,695,696

Deposits - Additional Informati

Deposits - Additional Information About Corporation's Deposits (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Deposit Liability [Line Items]
Deposits from foreign sources (primarily Mexico)	$ 1,069,964	$ 993,479
Non-interest-bearing public funds deposits	18,565,820	18,423,018
Interest-bearing public funds deposits	27,994,366	24,272,678
Total deposits not covered by deposit insurance	26,614,691	24,125,359
Time deposits not covered by deposit insurance	407,758	238,608
Public Funds [Member]
Deposit Liability [Line Items]
Non-interest-bearing public funds deposits	688,227	1,235,026
Interest-bearing public funds deposits	$ 746,671	$ 810,863

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Operating Lease, Right-of-Use Asset	$ 287,200		$ 287,200		$ 281,400
Operating Lease, Liability	319,900		319,900		$ 313,400
Lessee, Operating Lease, Liability, Payments, Due	$ 8,200	$ 7,900	24,600	$ 24,000
Significant change in expected future minimum lease payments since year end			$ 0

Commitments and Contingencies_2

Commitments and Contingencies - Financial Instruments with Off-Balance-Sheet Risk (Detail) - USD ($) $ in Thousands	Sep. 30, 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	$ 383,720	$ 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	2,144	2,072
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	$ 11,439,755	$ 10,420,142

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies - Credit Losses on Off-Balance-Sheet Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Off-Balance Sheet, Credit Loss, Liability	$ 50,246	$ 48,596	$ 50,314	$ 44,152
Credit loss expense (benefit)	2,463	3,023	2,395	7,467
Off-Balance Sheet, Credit Loss, Liability	$ 52,709	$ 51,619	$ 52,709	$ 51,619

Commitments and Contingencies_3

Commitments and Contingencies Commitments and Contingencies - Components of Lease Commitments Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Operating Lease, Right-of-Use Asset, Amortization Expense	$ 8,389	$ 8,172	$ 24,703	$ 24,584
Short-term lease expense	536	384	1,639	1,118
Non-lease components (including taxes, insurance, common maintenance, etc.)	3,092	2,864	8,860	8,205
Total operating lease expense, excluding rent	$ 12,017	$ 11,420	$ 35,202	$ 33,907

Capital and Regulatory Matter_2

Capital and Regulatory Matters - Additional Information (Detail) $ / shares in Units, $ in Millions			3 Months Ended	9 Months Ended		12 Months Ended
	Jan. 26, 2022 USD ($)	Nov. 19, 2020 USD ($)	Sep. 30, 2021 shares	Sep. 30, 2022 USD ($) quarter $ / shares shares	Sep. 30, 2021 shares	Dec. 31, 2021 USD ($) $ / shares shares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CECL Transition Amount				$ 46.2		$ 61.6
Treasury Stock, Shares, Acquired | shares			478	7,459	12,103
Maximum dividends available without prior regulatory approval				$ 619.6
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, shares issued | shares				150,000		150,000
Preferred Stock, Aggregate Liquidation Preference, Value				$ 150
Preferred stock, par value | $ / shares				$ 0.01		$ 0.01
Preferred Stock, Liquidation Preference Per Share | $ / shares				$ 1,000		$ 1,000
Number of Preferred Stock equivalent depositary shares | shares				40
Payments of Stock Issuance Costs		$ 4.5
Proceeds from Issuance of Preferred Stock and Preference Stock		$ 145.5
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				$ 145.5		$ 145.5
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		$ 120
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
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%		20%
Final years of the term of the notes				5 years		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		$ 100

Capital and Regulatory Matter_3

Capital and Regulatory Matters - Actual and Required Capital Ratios (Detail) - USD ($) $ in Thousands	Sep. 30, 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	$ 3,606,527	$ 3,371,043
Common Equity Tier 1 to Risk-Weighted Assets, Actual , Ratio	12.74%	13.13%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 1,981,042	$ 1,796,549
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased In, Ratio	7%	7%
Tier 1 Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 3,751,979	$ 3,516,495
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio	13.26%	13.70%
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,405,550	$ 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	$ 1,698,036	$ 1,539,899
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	6%	6%
Total Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 4,187,120	$ 3,966,244
Total Capital to Risk-Weighted Assets, Actual, Ratio	14.80%	15.45%
Total Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,971,562	$ 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	$ 2,830,059	$ 2,566,498
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	10%	10%
Leverage Ratio, Actual, Capital Amount	$ 3,751,979	$ 3,516,495
Leverage Ratio, Actual, Ratio	7.09%	7.34%
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,117,091	$ 1,917,533
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Ratio	4%	4%
Frost Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 to Risk-Weighted Assets, Actual, Capital Amount	$ 3,595,393	$ 3,261,532
Common Equity Tier 1 to Risk-Weighted Assets, Actual , Ratio	12.71%	12.72%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 1,979,976	$ 1,795,221
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased In, Ratio	7%	7%
Common Equity Tier 1 to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Capital Amount	$ 1,838,550	$ 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	$ 3,595,393	$ 3,261,532
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio	12.71%	12.72%
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,404,257	$ 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	$ 2,262,830	$ 2,051,681
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	8%	8%
Total Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 3,830,534	$ 3,491,281
Total Capital to Risk-Weighted Assets, Actual, Ratio	13.54%	13.61%
Total Capital to Risk-Weighted Assets, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,969,965	$ 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	$ 2,828,538	$ 2,564,601
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	10%	10%
Leverage Ratio, Actual, Capital Amount	$ 3,595,393	$ 3,261,532
Leverage Ratio, Actual, Ratio	6.79%	6.80%
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Capital Amount	$ 2,117,519	$ 1,917,679
Leverage Ratio, Minimum Capital Required - Basel III Fully Phased-In, Ratio	4%	4%
Leverage Ratio, Required to be Considered Well Capitalized, Capital Amount	$ 2,646,898	$ 2,397,099
Leverage Ratio, Required to be Considered Well Capitalized, Ratio	5%	5%

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Derivative [Line Items]
Weighted-average strike rate for outstanding interest rate caps	3.29%
Approximate credit exposure related to swaps with bank customers	$ 58,400
Pledged Assets Separately Reported, Securities Pledged as Collateral, at Fair Value	10,900
Cash collateral for borrowed securities deposited with other financial institutions	12,900
Interest rate swaps with upstream financial institution counterparties [Member]
Derivative [Line Items]
Approximate credit exposure related to swaps with bank customers	20,200
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

Derivative Financial Instrume_4

Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding (Detail) - USD ($) $ in Thousands	Sep. 30, 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	$ 1,679	$ 0
Estimated Fair Value	25	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	0	2,426
Estimated Fair Value	0	(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	1,229,040	247,592
Estimated Fair Value	61,992	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	126,112	928,756
Estimated Fair Value	(1,088)	(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	243,840	270,431
Estimated Fair Value	15,777	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	67,780	928,756
Estimated Fair Value	1,104	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	1,185,815	247,592
Estimated Fair Value	(82,228)	(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	243,840	270,431
Estimated Fair Value	$ (15,777)	$ (3,239)

Derivative Financial Instrume_5

Derivative Financial Instruments - Schedule of Weighted-Average Rates Paid and Received for Interest Rate Swaps Outstanding (Detail)	Sep. 30, 2022
Weighted Average Interest Rate Paid [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Fair value hedge loan/lease interest rate swaps	1.58%
Weighted-Average Interest Rate Received [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Fair value hedge loan/lease interest rate swaps	2.56%
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	3.74%
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	4.23%
Customer Counterparties [Member] | Weighted Average Interest Rate Paid [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – customer counterparties	4.21%
Customer Counterparties [Member] | Weighted-Average Interest Rate Received [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – customer counterparties	3.73%

Derivative Financial Instrume_6

Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Commodity Derivative Positions (Detail) bbl in Thousands, MMBTU in Thousands, $ in Thousands	Sep. 30, 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	4,467	4,809
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	6,987	7,032
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 45,381	$ 14,721
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (55,645)	$ (73,594)
Financial Institution Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	13,406	15,947
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	20,489	29,446
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 4,033	$ 4,143
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (40,049)	$ (21,249)
Customer Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	7,006	7,046
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	4,448	4,796
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 56,366	$ 74,437
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (44,674)	$ (14,294)
Customer Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	20,489	29,446
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	13,406	15,947
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 40,153	$ 21,456
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (4,017)	$ (4,124)

Derivative Financial Instrume_7

Derivative Financial Instruments - Schedule of Notional Amounts and Fair Values of Open Foreign Currency Forward Contracts (Details) € in Thousands, $ in Thousands, $ in Thousands	Sep. 30, 2022 USD ($)	Sep. 30, 2022 EUR (€)	Sep. 30, 2022 CAD ($)	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	$ 1			$ 29
Forward Contracts - Liability Estimated Fair Value	(251)			0
Financial Institution Counterparties [Member] | Foreign Exchange Forward [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	0			0
Financial Institution Counterparties [Member] | Other Assets [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Notional Amount		€ 2,925	$ 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 | €		2,925			0
Customer Counterparties [Member] | GBP Foreign Exchange Forward
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	251			0
Forward Contracts - Liability Estimated Fair Value	(1)			(55)
Customer Counterparties [Member] | Foreign Exchange Forward [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value	$ 0			$ 4
Customer Counterparties [Member] | Other Assets [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Notional Amount		2,925	$ 0		0	$ 658
Customer Counterparties [Member] | Other Liabilities [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Liability Notional Amount | €		€ 2,925			€ 1,900

Derivative Financial Instrume_8

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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Interest Income on Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) included in income	$ 2	$ (21)	$ (16)	$ (74)
Other Non-Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) included in income	$ 1	$ 3	$ 6	$ 8

Derivative Financial Instrume_9

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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 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)	$ 140	$ 946	$ 1,171	$ 2,674
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	0	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)	485	1,143	2,063	3,266
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)	$ 0	$ 4	$ 63	$ 34

Balance Sheet Offsetting - Fina

Balance Sheet Offsetting - Financial Instruments Eligible for Offset Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	$ 127,209	$ 23,339
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	127,209	23,339
Gross Amount Recognized, Resell agreements, Financial assets	12,150	7,903
Gross Amount Offset, Resell agreements, Financial assets	0	0
Net Amount Recognized, Resell agreements, Financial assets	12,150	7,903
Gross Amount Recognized, Financial assets	139,359	31,242
Gross Amount Offset, Financial assets	0	0
Net Amount Recognized, Financial assets	139,359	31,242
Gross Amount Recognized, Derivatives, Financial Liabilities	97,033	114,019
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	97,033	114,019
Gross Amount Recognized, Repurchase agreements, Financial liabilities	2,082,739	2,740,799
Gross Amount Offset, Repurchase agreements, Financial liabilities	0	0
Net Amount Recognized, Repurchase agreements, Financial liabilities	2,082,739	2,740,799
Gross Amount Recognized, Financial liabilities	2,179,772	2,854,818
Gross Amount Offset, Financial liabilities	0	0
Net Amount Recognized, Financial Liabilities	2,179,772	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	77,794	4,446
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	77,794	4,446
Gross Amount Recognized, Derivatives, Financial Liabilities	1,088	19,176
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	1,088	19,176
Commodity swaps and options [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	49,414	18,864
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	49,414	18,864
Gross Amount Recognized, Derivatives, Financial Liabilities	95,694	94,843
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	95,694	$ 94,843
Foreign currency forward contracts [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	1
Gross Amount Offset, Derivatives, Financial assets	0
Net Amount Recognized, Derivatives, Financial assets	1
Gross Amount Recognized, Derivatives, Financial Liabilities	251
Gross Amount Offset, Derivatives, Financial liabilities	0
Net Amount Recognized, Derivatives, Financial liabilities	$ 251

Balance Sheet Offsetting - Fi_2

Balance Sheet Offsetting - Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 127,209	$ 23,339
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(89,314)	(23,339)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(33,803)	0
Net Amount, Derivatives, Financial Assets	4,092	0
Net Amount Recognized, Resell agreements, Financial Assets	12,150	7,903
Gross Amounts Not Offset Financial Instruments, Resell Agreements	0	0
Gross Amounts Not Offset Collateral, Resell Agreements, Financial Assets	(12,150)	(7,903)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	139,359	31,242
Gross Amounts Not Offset Collateral, Financial Assets	(45,953)	(7,903)
Net Amount, Financial Assets	4,092	0
Net Amount Recognized, Derivatives, Financial Liabilities	97,033	114,019
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(89,314)	(23,339)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(7,716)	(90,573)
Net Amount, Derivatives, Financial Liabilities	3	107
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	2,082,739	2,740,799
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(2,082,739)	(2,740,799)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Total Financial Liabilities	2,179,772	2,854,818
Gross Amounts Not Offset Collateral, Financial Liabilities	(2,090,455)	(2,831,372)
Net Amount, Financial Liabilities	3	107
Counterparty A [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	47	6
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(47)	(6)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0	0
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	1,081	3,870
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(47)	(6)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(1,031)	(3,864)
Net Amount, Derivatives, Financial Liabilities	3	0
Counterparty B [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	44,271	7,655
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(35,853)	(7,655)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(6,063)	0
Net Amount, Derivatives, Financial Assets	2,355	0
Net Amount Recognized, Derivatives, Financial Liabilities	35,853	28,130
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(35,853)	(7,655)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(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 Assets	407
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(251)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	0
Net Amount, Derivatives, Financial Assets	156
Net Amount Recognized, Derivatives, Financial Liabilities	251	9
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(251)	0
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(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	82,484	15,678
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(53,163)	(15,678)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(27,740)	0
Net Amount, Derivatives, Financial Assets	1,581	0
Net Amount Recognized, Derivatives, Financial Liabilities	59,848	82,010
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(53,163)	(15,678)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	(6,685)	(66,225)
Net Amount, Derivatives, Financial Liabilities	$ 0	$ 107

Balance Sheet Offsetting Balanc

Balance Sheet Offsetting Balance Sheet Offsetting - Remaining Contractual Maturity of the Securities Sold Under Agreement to Repurchase (Details) - USD ($) $ in Thousands	Sep. 30, 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	$ 2,082,739	$ 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	2,082,739	2,740,799
Securities Sold under Agreements to Repurchase, Gross	2,082,739	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	1,348,705	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	1,348,705	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	734,034	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	$ 734,034	$ 1,398,208

Stock-Based Compensation Stock-

Stock-Based Compensation Stock-Based Compensation - Narrative (Details)	Sep. 30, 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	789,290

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Activity in Corporation's Active Stock Plans (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised, Number of Shares	(88,350)	(21,968)	(232,612)	(650,044)
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
Granted, Number of Units			5,382
Stock Awards exercised/vested, Number of Shares			(16,022)
Ending Balance, Number of Shares/Units	45,661		45,661
Beginning Balance, Weighted-Average Grant-Date Fair Value			$ 79.21
Granted Weighted-Average Grant-Date Fair Value			133.67
Stock Award Exercised/Vested, Weighted Average Grant Date Fair Value			74.89
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 87.15		$ 87.15
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			4,676
Forfeited/expired, Number of Shares/Units			(5,603)
Ending Balance, Number of Shares/Units	448,410		448,410
Beginning Balance, Weighted-Average Grant-Date Fair Value			$ 93.05
Granted Weighted-Average Grant-Date Fair Value			130.30
Forfeited/Expired, Weighted-Average Price			93.69
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 93.43		$ 93.43
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			(191,410)
Ending Balance, Number of Shares	686,271		686,271
Beginning Balance, Weighted-Average Exercise Price			$ 69.02
Stock options exercised, Weighted-Average Exercise Price			61.44
Ending Balance, Weighted-Average Exercise Price	$ 71.14		$ 71.14
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		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		$ 84.08

Stock-Based Compensation - Shar

Stock-Based Compensation - Shares Issued in Connection with Stock Compensation Awards (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
New shares issued from available authorized shares	0	0	0	0
Shares issued from available treasury stock	88,350	21,968	232,612	650,044
Proceeds from stock option exercises	$ 5,270	$ 1,128	$ 11,760	$ 37,810

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 3,173	$ 1,985	$ 8,703	$ 7,756
Income tax benefit	440	281	1,760	1,162
Non-Vested Stock Awards/Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	2,174	1,559	6,823	5,210
Director deferred stock units outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	0	0	720	700
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	$ 999	$ 426	$ 1,160	$ 1,846

Stock-Based Compensation - Unre

Stock-Based Compensation - Unrecognized Stock-Based Compensation Expense (Detail) $ in Thousands	Sep. 30, 2022 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock units	$ 11,704
Performance stock units	7,257
Total	$ 18,961

Earnings Per Common Share - Bas

Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net income	$ 169,760	$ 107,975	$ 387,976	$ 342,058
Less: Preferred stock dividends	1,668	1,668	5,006	5,488
Net income available to common shareholders	168,092	106,307	382,970	336,570
Less: Earnings allocated to participating securities	1,503	932	3,414	3,228
Distributed earnings allocated to common stock	55,820	47,740	151,963	139,224
Undistributed earnings allocated to common stock	110,769	57,635	227,593	194,118
Net earnings allocated to common stock	$ 166,589	$ 105,375	$ 379,556	$ 333,342
Weighted-average shares outstanding for basic earnings per common share	64,157,662	63,652,020	64,107,621	63,522,884
Dilutive effect of stock compensation	343,750	444,636	369,268	489,219
Weighted-average shares outstanding for diluted earnings per common share	64,501,412	64,096,656	64,476,889	64,012,103

Defined Benefit Plans Additiona

Defined Benefit Plans Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 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

Defined Benefit Plans - Net Per

Defined Benefit Plans - Net Periodic Cost (Benefit) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Retirement Benefits [Abstract]
Expected return on plan assets, net of expenses	$ (3,492)	$ (3,210)	$ (10,475)	$ (9,630)
Interest cost on projected benefit obligation	1,005	835	3,013	2,506
Net amortization and deferral	741	1,529	2,223	4,587
Net periodic expense (benefit)	$ (1,746)	$ (846)	$ (5,239)	$ (2,537)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	$ 420.9		$ 420.9
Deferred Tax Liabilities, Net					$ 81.2
Valuation allowance	$ 0		$ 0
U.S. federal statutory income tax rate, percent	21%	21%	21%	21%
Unrecognized tax benefits	$ 0	$ 0	$ 0	$ 0

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Current income tax expense (benefit)	$ 28,684	$ 13,849	$ 64,389	$ 31,639
Deferred income tax expense (benefit)	(974)	(516)	(3,378)	4,672
Income tax expense, as reported	$ 27,710	$ 13,333	$ 61,011	$ 36,311
Effective tax rate	14%	11%	13.60%	9.60%

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - Component of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Equity [Abstract]
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Before Tax Amount	$ (829,324)	$ (80,668)	$ (2,376,642)	$ (209,779)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Before Tax Amount	(174)	(237)	(572)	(741)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Before Tax Amount	0	0	0	0
Total securities available for sale and transferred securities, before tax amount	(829,498)	(80,905)	(2,377,214)	(210,520)
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	2,223	4,587
Total defined-benefit post-retirement benefit plans	741	1,529	2,223	4,587
Total other comprehensive income (loss), before tax	(828,757)	(79,376)	(2,374,991)	(205,933)
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Tax Expense (Benefit)	(174,158)	(16,941)	(499,095)	(44,054)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Tax Expense (Benefit)	(36)	(49)	(120)	(155)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Tax Expense (Benefit)	0	0	0	0
Total securities available for sale and transferred securities, Tax Expense (Benefit)	(174,194)	(16,990)	(499,215)	(44,209)
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	467	963
Total defined-benefit post-retirement benefit plans, Tax Expense (Benefit)	156	321	467	963
Total other comprehensive income (loss), Tax Expense (Benefit)	(174,038)	(16,669)	(498,748)	(43,246)
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Net of Tax	(655,166)	(63,727)	(1,877,547)	(165,725)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Net of Tax	(138)	(188)	(452)	(586)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Net of Tax	0	0	0	0
Total securities available for sale and transferred securities, Net of Tax	(655,304)	(63,915)	(1,877,999)	(166,311)
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	1,756	3,624
Total defined-benefit post-retirement benefit plans, Net of Tax Amount	585	1,208	1,756	3,624
Other comprehensive income (loss), net of tax	$ (654,719)	$ (62,707)	$ (1,876,243)	$ (162,687)

Other Comprehensive Income - Sc

Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ 347,318
Other comprehensive income (loss), net of tax	$ (654,719)	$ (62,707)	(1,876,243)	$ (162,687)
Ending Balance	(1,528,925)		(1,528,925)
Securities Available For Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			380,209	563,801
Other comprehensive income (loss) before reclassifications			(1,877,999)	(166,311)
Reclassification of amounts included in net income			0	0
Other comprehensive income (loss), net of tax			(1,877,999)	(166,311)
Ending Balance	(1,497,790)	397,490	(1,497,790)	397,490
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			1,756	3,624
Other comprehensive income (loss), net of tax			1,756	3,624
Ending Balance	(31,135)	(47,207)	(31,135)	(47,207)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			347,318	512,970
Other comprehensive income (loss) before reclassifications			(1,877,999)	(166,311)
Reclassification of amounts included in net income			1,756	3,624
Other comprehensive income (loss), net of tax			(1,876,243)	(162,687)
Ending Balance	$ (1,528,925)	$ 350,283	$ (1,528,925)	$ 350,283

Operating Segments - Additional

Operating Segments - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2022 Segment
Segment Reporting [Abstract]
Number of primary operating segments	2

Operating Segments - Summary of

Operating Segments - Summary of Operating Results by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	$ 355,547	$ 246,122	$ 892,826	$ 744,159
Credit loss expense	0	0	0	63
Total non-interest income	99,821	93,189	299,138	277,672
Total non-interest expense	257,898	218,003	742,977	643,399
Income (loss) before income taxes	197,470	121,308	448,987	378,369
Income tax expense (benefit)	27,710	13,333	61,011	36,311
Net income (loss)	169,760	107,975	387,976	342,058
Preferred stock dividends	1,668	1,668	5,006	5,488
Net income (loss) available to common shareholders	168,092	106,307	382,970	336,570
Revenues from (expenses to) external customers	455,368	339,311	1,191,964	1,021,831
Bank
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	356,513	247,381	895,818	748,036
Credit loss expense	(1)	(6)	(1)	57
Total non-interest income	55,994	51,279	170,097	154,003
Total non-interest expense	223,193	185,891	640,775	548,151
Income (loss) before income taxes	189,315	112,775	425,141	353,831
Income tax expense (benefit)	26,520	12,029	57,355	32,811
Net income (loss)	162,795	100,746	367,786	321,020
Preferred stock dividends	0	0	0	0
Net income (loss) available to common shareholders	162,795	100,746	367,786	321,020
Revenues from (expenses to) external customers	412,507	298,660	1,065,915	902,039
Frost Wealth Advisors [Member]
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	1,357	536	3,015	1,530
Credit loss expense	1	6	1	6
Total non-interest income	44,263	42,369	130,546	124,512
Total non-interest expense	33,530	31,086	97,598	91,037
Income (loss) before income taxes	12,089	11,813	35,962	34,999
Income tax expense (benefit)	2,539	2,481	7,552	7,350
Net income (loss)	9,550	9,332	28,410	27,649
Preferred stock dividends	0	0	0	0
Net income (loss) available to common shareholders	9,550	9,332	28,410	27,649
Revenues from (expenses to) external customers	45,620	42,905	133,561	126,042
Non-Banks [Member]
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	(2,323)	(1,795)	(6,007)	(5,407)
Credit loss expense	0	0	0	0
Total non-interest income	(436)	(459)	(1,505)	(843)
Total non-interest expense	1,175	1,026	4,604	4,211
Income (loss) before income taxes	(3,934)	(3,280)	(12,116)	(10,461)
Income tax expense (benefit)	(1,349)	(1,177)	(3,896)	(3,850)
Net income (loss)	(2,585)	(2,103)	(8,220)	(6,611)
Preferred stock dividends	1,668	1,668	5,006	5,488
Net income (loss) available to common shareholders	(4,253)	(3,771)	(13,226)	(12,099)
Revenues from (expenses to) external customers	$ (2,759)	$ (2,254)	$ (7,512)	$ (6,250)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 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

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Financial Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 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	$ 17,399,107	$ 13,924,628
Trading account securities	25,008	25,162
Derivative assets	127,209	23,339
Derivative liabilities	97,033	114,019
Interest rate swaps, caps and floors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	78,898	44,310
Derivative liabilities	99,093	25,261
Commodity swaps and options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	145,933	114,757
Derivative liabilities	144,385	113,261
Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	252	33
Derivative liabilities	252	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	5,022,617	2,179,433
Trading account securities	25,008	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	5,698,809	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	6,635,298	7,636,571
Trading account securities		925
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	42,383	42,359
Level 1 [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	252	33
Derivative liabilities	252	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	5,022,617	2,179,433
Trading account securities	25,008	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	78,898	44,310
Derivative liabilities	99,093	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	145,933	114,757
Derivative liabilities	144,385	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	5,698,809	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	6,635,298	7,636,571
Trading account securities		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	$ 42,383	$ 42,359

Fair Value Measurements - Impai

Fair Value Measurements - Impaired Loans Remeasured and Reported at Fair Value of Underlying Collateral (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Carrying value of impaired loans before allocations	$ 7,999	$ 3,329
Impaired Financing Receivable, Related Allowance	(1,742)	(336)
Loans receivable, fair value disclosure	6,257	2,993
Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Carrying value of impaired loans before allocations	2,087	15,274
Impaired Financing Receivable, Related Allowance		(4,791)
Impaired Financing Receivable, Reversal of Specific Valuation Allowance Allocations	4,881
Loans receivable, fair value disclosure	$ 6,968	$ 10,483

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 13,632,698	$ 16,583,000	$ 16,253,971	$ 10,288,853
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Loans, net	16,716,314	16,087,731
Deposits	46,560,186	42,695,696
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior subordinated deferrable interest debentures	123,055	123,011
Subordinated notes	99,295	99,178
Carrying Amount [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	13,632,698	16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	2,174,084	1,749,179
Cash surrender value of life insurance policies	190,368	190,139
Accrued interest receivable	169,540	179,111
Deposits	46,560,186	42,695,696
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior subordinated deferrable interest debentures	123,055	123,011
Subordinated notes	99,295	99,178
Accrued interest payable	9,545	3,026
Carrying Amount [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	16,716,314	16,087,731
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	13,632,698	16,583,000
Securities held to maturity, net of allowance for credit losses of $158 at September 30, 2022 and $158 at December 31, 2021	1,917,287	1,809,143
Cash surrender value of life insurance policies	190,368	190,139
Accrued interest receivable	169,540	179,111
Deposits	46,538,352	41,343,426
Federal funds purchased	26,200	25,925
Repurchase agreements	2,082,739	2,740,799
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes	96,926	111,430
Accrued interest payable	9,545	3,026
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 16,163,170	$ 16,079,454