Cullen/Frost Bankers (CFR) 10-Q 27 Jul 23 2023 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	6 Months Ended
	Jun. 30, 2023	Jul. 20, 2023	Dec. 31, 2022
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
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		64,123,111
Common stock, par value	$ 0.01		$ 0.01
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
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	Jun. 30, 2023	Dec. 31, 2022
Assets:
Cash and due from banks	$ 680,843	$ 691,553
Interest-bearing deposits	6,329,268	11,128,902
Federal funds sold	12,575	120,527
Resell agreements	84,650	87,150
Total cash and cash equivalents	7,107,336	12,028,132
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	3,691,220	2,639,083
Securities available for sale, at estimated fair value	17,249,257	18,243,605
Trading account securities	32,517	28,045
Loans, net of unearned discounts	17,746,311	17,154,969
Less: Allowance for credit losses on loans	(233,619)	(227,621)
Net loans	17,512,692	16,927,348
Premises and equipment, net	1,154,235	1,102,695
Goodwill	654,952	654,952
Other intangible assets, net	208	386
Cash surrender value of life insurance policies	190,575	190,188
Accrued interest receivable and other assets	1,004,208	1,077,942
Total assets	48,597,200	52,892,376
Liabilities:
Non-interest-bearing demand deposits	14,904,614	17,598,234
Interest-bearing deposits	25,796,216	26,355,962
Total deposits	40,700,830	43,954,196
Federal funds purchased	13,525	51,650
Repurchase agreements	3,569,870	4,660,641
Junior subordinated deferrable interest debentures, net of unamortized issuance costs	123,098	123,069
Subordinated notes, net of unamortized issuance costs	99,413	99,335
Accrued interest payable and other liabilities	703,722	866,257
Total liabilities	45,210,458	49,755,148
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 June 30, 2023 and December 31, 2022	145,452	145,452
Common stock, par value $0.01 per share; 210,000,000 shares authorized; 64,404,582 shares issued at June 30, 2023 and 64,354,695 at December 31, 2022	644	643
Additional paid-in capital	1,040,754	1,029,756
Retained earnings	3,532,542	3,309,671
Accumulated other comprehensive income (loss), net of tax	(1,305,027)	(1,348,294)
Treasury stock, at cost; 284,206 shares at June 30, 2023	(27,623)	0
Total shareholders’ equity	3,386,742	3,137,228
Total liabilities and shareholders’ equity	$ 48,597,200	$ 52,892,376

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Securities, held-to-maturity, allowance for credit loss	$ 267	$ 158
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	210,000,000	210,000,000
Common stock, shares issued	64,404,582	64,354,695
Treasury stock, shares	284,206
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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Interest income:
Loans, including fees	$ 290,552	$ 166,679	$ 560,267	$ 316,656
Securities:
Taxable	101,960	56,365	199,735	99,423
Tax-exempt	60,637	57,078	127,271	113,944
Interest-bearing deposits	87,748	26,371	186,993	32,714
Federal funds sold	305	99	1,063	112
Resell agreements	1,126	10	2,194	14
Total interest income	542,328	306,602	1,077,523	562,863
Interest expense:
Deposits	120,266	14,593	218,255	19,505
Federal funds purchased	412	75	995	87
Repurchase agreements	33,114	1,790	66,765	2,308
Junior subordinated deferrable interest debentures	2,106	772	4,094	1,356
Subordinated notes	1,164	1,164	2,328	2,328
Total interest expense	157,062	18,394	292,437	25,584
Net interest income	385,266	288,208	785,086	537,279
Credit loss expense	9,901	0	19,005	0
Net interest income after credit loss expense	375,365	288,208	766,081	537,279
Non-interest income:
Trust and investment management fees	39,392	37,776	75,536	76,432
Service charges on deposit accounts	23,487	23,870	45,366	46,610
Insurance commissions and fees	12,940	11,776	31,892	28,384
Interchange and card transaction fees	5,250	4,911	10,139	9,137
Other charges, commissions and fees	12,090	9,887	23,794	19,514
Net gain (loss) on securities transactions	33	0	54	0
Other	10,336	9,707	22,012	19,240
Total non-interest income	103,528	97,927	208,793	199,317
Non-interest expense:
Salaries and wages	133,195	116,881	263,540	228,210
Employee benefits	26,792	20,733	60,714	44,953
Net occupancy	31,714	28,379	62,063	55,790
Technology, furniture and equipment	33,043	29,921	65,524	59,078
Deposit insurance	6,202	3,724	12,447	7,357
Intangible amortization	82	131	178	277
Other	54,014	46,578	105,718	89,414
Total non-interest expense	285,042	246,347	570,184	485,079
Income before income taxes	193,851	139,788	404,690	251,517
Income taxes	31,733	20,674	64,919	33,301
Net income	162,118	119,114	339,771	218,216
Preferred stock dividends	1,669	1,669	3,338	3,338
Net income available to common shareholders	$ 160,449	$ 117,445	$ 336,433	$ 214,878
Earnings per common share:
Basic	$ 2.47	$ 1.82	$ 5.18	$ 3.32
Diluted	$ 2.47	$ 1.81	$ 5.17	$ 3.31

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net income	$ 162,118	$ 119,114	$ 339,771	$ 218,216
Other comprehensive income (loss), before tax:
Change in net unrealized gain/loss on securities available for sale during the period	(206,863)	(636,523)	53,406	(1,547,318)
Change in net unrealized gain on securities transferred to held to maturity	(162)	(189)	(322)	(398)
Reclassification adjustment for net (gains) losses included in net income	(33)	0	(54)	0
Total securities available for sale and transferred securities, before tax amount	(207,058)	(636,712)	53,030	(1,547,716)
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)	870	741	1,740	1,482
Total defined-benefit post-retirement benefit plans	870	741	1,740	1,482
Other comprehensive income (loss), before tax	(206,188)	(635,971)	54,770	(1,546,234)
Deferred tax expense (benefit)	(43,299)	(133,555)	11,503	(324,710)
Other comprehensive income (loss), net of tax	(162,889)	(502,416)	43,267	(1,221,524)
Comprehensive income (loss)	$ (771)	$ (383,302)	$ 383,038	$ (1,003,308)

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, Common
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	218,216				218,216
Other comprehensive income (loss)	(1,221,524)					(1,221,524)
Stock option exercises/stock unit conversions (13,626 shares QTD and 64,013 shares YTD in 2023 and 28,832 shares QTD and 144,262 shares YTD in 2022)	6,490				(4,777)		11,267
Stock compensation expense recognized in earnings	5,530			5,530
Purchase of treasury stock (289,149 shares QTD and 298,332 shares YTD in 2023 and 7,459 shares YTD in 2022)	(996)						(996)
Cash dividends – preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depository share QTD in 2023 and 2022, respectively and approximately $22.25 per share which is equivalent to approximately $0.56 per depository share YTD in 2023 and 2022, respectively )	(3,338)				(3,338)
Cash dividends – common stock ($0.87 per share QTD and $1.74 per share YTD in 2023 and $0.75 per share QTD and $1.50 per share YTD in 2022)	(96,958)				(96,958)
Total shareholders’ equity at end of period at Jun. 30, 2022	3,346,975	145,452	642	1,015,451	3,070,109	(874,206)	(10,473)
Total shareholders’ equity at beginning of period at Mar. 31, 2022	3,776,292	145,452	642	1,012,033	3,002,642	(371,790)	(12,687)
Net income	119,114				119,114
Other comprehensive income (loss)	(502,416)					(502,416)
Stock option exercises/stock unit conversions (13,626 shares QTD and 64,013 shares YTD in 2023 and 28,832 shares QTD and 144,262 shares YTD in 2022)	751				(1,463)		2,214
Stock compensation expense recognized in earnings	3,418			3,418
Cash dividends – preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depository share QTD in 2023 and 2022, respectively and approximately $22.25 per share which is equivalent to approximately $0.56 per depository share YTD in 2023 and 2022, respectively )	(1,669)				(1,669)
Cash dividends – common stock ($0.87 per share QTD and $1.74 per share YTD in 2023 and $0.75 per share QTD and $1.50 per share YTD in 2022)	(48,515)				(48,515)
Total shareholders’ equity at end of period at Jun. 30, 2022	3,346,975	145,452	642	1,015,451	3,070,109	(874,206)	(10,473)
Total shareholders’ equity at beginning of period at Dec. 31, 2022	3,137,228	145,452	643	1,029,756	3,309,671	(1,348,294)	0
Net income	339,771				339,771
Other comprehensive income (loss)	43,267					43,267
Stock option exercises/stock unit conversions (13,626 shares QTD and 64,013 shares YTD in 2023 and 28,832 shares QTD and 144,262 shares YTD in 2022)	2,446		1	1,463	(519)		1,501
Stock compensation expense recognized in earnings	9,535			9,535
Purchase of treasury stock (289,149 shares QTD and 298,332 shares YTD in 2023 and 7,459 shares YTD in 2022)	(29,124)						(29,124)
Cash dividends – preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depository share QTD in 2023 and 2022, respectively and approximately $22.25 per share which is equivalent to approximately $0.56 per depository share YTD in 2023 and 2022, respectively )	(3,338)				(3,338)
Cash dividends – common stock ($0.87 per share QTD and $1.74 per share YTD in 2023 and $0.75 per share QTD and $1.50 per share YTD in 2022)	(113,043)				(113,043)
Total shareholders’ equity at end of period at Jun. 30, 2023	3,386,742	145,452	644	1,040,754	3,532,542	(1,305,027)	(27,623)
Total shareholders’ equity at beginning of period at Mar. 31, 2023	3,467,801	145,452	644	1,035,961	3,428,991	(1,142,138)	(1,109)
Net income	162,118				162,118
Other comprehensive income (loss)	(162,889)					(162,889)
Stock option exercises/stock unit conversions (13,626 shares QTD and 64,013 shares YTD in 2023 and 28,832 shares QTD and 144,262 shares YTD in 2022)	946				(491)		1,437
Stock compensation expense recognized in earnings	4,793			4,793
Purchase of treasury stock (289,149 shares QTD and 298,332 shares YTD in 2023 and 7,459 shares YTD in 2022)	(27,951)						(27,951)
Cash dividends – preferred stock (approximately $11.13 per share which is equivalent to approximately $0.28 per depository share QTD in 2023 and 2022, respectively and approximately $22.25 per share which is equivalent to approximately $0.56 per depository share YTD in 2023 and 2022, respectively )	(1,669)				(1,669)
Cash dividends – common stock ($0.87 per share QTD and $1.74 per share YTD in 2023 and $0.75 per share QTD and $1.50 per share YTD in 2022)	(56,407)				(56,407)
Total shareholders’ equity at end of period at Jun. 30, 2023	$ 3,386,742	$ 145,452	$ 644	$ 1,040,754	$ 3,532,542	$ (1,305,027)	$ (27,623)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Stockholders' Equity [Abstract]
Stock option exercise/stock unit conversions (13,626 shares QTD and 64,013 shares YTD in 2023 and 28,832 shares QTD and 144,262 shares YTD during 2022)	13,626	28,832	64,013	144,262
Purchase of treasury stock (289,149 shares QTD and 298,332 shares YTD in 2023 and 7,459 shares YTD in 2022)	289,149		298,332	7,459
Cash dividend - preferred stock (Approximately $11.13 per share QTD and $22.25 per share YTD in 2023 and 2022, respectively)	$ 11.13	$ 11.13	$ 22.25	$ 22.25
Cash dividend - Preferred Stock Dividends equivalent Per depositary Share Declared ($0.28 QTD and $0.56 YTD during 2023 and 2022)	0.28	0.28	0.56	0.56
Cash dividends - common stock ($0.87 per share QTD and $1.74 per share YTD in 2023 and $0.75 per share QTD and $1.50 per share YTD in 2022)	$ 0.87	$ 0.75	$ 1.74	$ 1.50

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Operating Activities:
Net income	$ 339,771	$ 218,216
Adjustments to reconcile net income to net cash from operating activities:
Credit loss expense	19,005	0
Deferred tax expense (benefit)	(2,489)	(2,404)
Accretion of loan discounts	(9,265)	(6,581)
Securities premium amortization (discount accretion), net	36,919	53,225
Net (gain) loss on securities transactions	(54)	0
Depreciation and amortization	37,076	35,406
Net (gain) loss on sale/write-down of assets/foreclosed assets	(283)	103
Stock-based compensation	9,535	5,530
Net tax benefit from stock-based compensation	469	1,645
Earnings on life insurance policies	(1,387)	(1,016)
Net change in:
Trading account securities	335	482
Lease right-of-use assets	11,193	12,042
Accrued interest receivable and other assets	59,051	(135,239)
Accrued interest payable and other liabilities	(176,718)	113,645
Net cash from operating activities	323,158	295,054
Investing Activities:
Securities held-to-maturity - Purchases	(1,141,443)	(411,527)
Securities held to maturity: Maturities, calls and principal repayments	92,547	263,226
Securities available for sale:
Purchases	(7,607,014)	(4,778,475)
Sales	1,543,355	0
Maturities, calls and principal repayments	7,077,003	382,152
Proceeds from sale of loans	2,215	2,365
Net change in loans	(602,902)	(404,515)
Benefits received on life insurance policies	1,000	1,332
Proceeds from sales of premises and equipment	1,179	18
Purchases of premises and equipment	(85,156)	(28,016)
Proceeds from sales of repossessed properties	583	1,543
Net cash from investing activities	(718,633)	(4,971,897)
Financing Activities:
Net change in deposits	(3,253,366)	2,906,069
Net change in short-term borrowings	(1,128,896)	(1,058,839)
Proceeds from stock option exercises	2,446	6,490
Purchase of treasury stock	(29,124)	(996)
Cash dividends paid on preferred stock	(3,338)	(3,338)
Cash dividends paid on common stock	(113,043)	(96,958)
Net cash from financing activities	(4,525,321)	1,752,428
Net change in cash and cash equivalents	(4,920,796)	(2,924,415)
Cash and cash equivalents at beginning of period	12,028,132	16,583,000
Cash and cash equivalents at end of period	$ 7,107,336	$ 13,658,585

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2023
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, 2022, included in our Annual Report on Form 10-K filed with the SEC on February 3, 2023 (the “ 2022 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: Six Months Ended 2023 2022 Cash paid for interest $ 270,358 $ 22,551 Cash paid for income taxes 66,500 45,500 Significant non-cash transactions: Unsettled securities transactions 10,988 110,623 Right-of-use lease assets obtained in exchange for lessee operating lease liabilities 8,914 8,857

Securities

Securities	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023 and December 31, 2022 is presented below. Amortized Gross Gross Estimated Allowance Net June 30, 2023 Residential mortgage-backed securities $ 1,265,818 $ — $ 72,286 $ 1,193,532 $ — $ 1,265,818 States and political subdivisions 2,424,169 24,288 99,491 2,348,966 (267) 2,423,902 Other 1,500 — 69 1,431 — 1,500 Total $ 3,691,487 $ 24,288 $ 171,846 $ 3,543,929 $ (267) $ 3,691,220 December 31, 2022 Residential mortgage-backed securities $ 526,122 $ — $ 65,322 $ 460,800 $ — $ 526,122 States and political subdivisions 2,111,619 13,048 119,033 2,005,634 (158) 2,111,461 Other 1,500 — 69 1,431 — 1,500 Total $ 2,639,241 $ 13,048 $ 184,424 $ 2,467,865 $ (158) $ 2,639,083 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 $943.9 million and $256.3 million at June 30, 2023 and December 31, 2022, respectively. Accrued interest receivable on held-to-maturity securities totaled $39.4 million and $30.2 million at June 30, 2023 and December 31, 2022, 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 $1.5 million ($1.2 million, net of tax) at June 30, 2023 and $1.8 million ($1.4 million, net of tax) at December 31, 2022. 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 June 30, 2023 and December 31, 2022: States and Political Subdivisions Not Guaranteed or Pre-Refunded Guaranteed by the Texas PSF Guaranteed by Third Party Pre-Refunded Total Other June 30, 2023 Aaa/AAA $ 301,922 $ 1,544,702 $ 13,656 $ 52,860 $ 1,913,140 $ — Aa/AA 504,928 — 6,101 — 511,029 — Not rated — — — — — 1,500 Total $ 806,850 $ 1,544,702 $ 19,757 $ 52,860 $ 2,424,169 $ 1,500 December 31, 2022 Aaa/AAA $ 273,201 $ 1,422,442 $ — $ 121,961 $ 1,817,604 $ — Aa/AA 294,015 — — — 294,015 — Not rated — — — — — 1,500 Total $ 567,216 $ 1,422,442 $ — $ 121,961 $ 2,111,619 $ 1,500 The following table details activity in the allowance for credit losses on held-to-maturity securities during the three and six months ended June 30, 2023 and 2022. Three Months Ended Six Months Ended 2023 2022 2023 2022 Beginning balance $ 262 $ 158 $ 158 $ 158 Credit loss expense (benefit) 5 — 109 — Ending balance $ 267 $ 158 $ 267 $ 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 June 30, 2023 and December 31, 2022 is presented below. Amortized Gross Gross Allowance Estimated June 30, 2023 U.S. Treasury $ 5,456,656 $ — $ 383,768 $ — $ 5,072,888 Residential mortgage-backed securities 7,725,403 5,105 937,733 — 6,792,775 States and political subdivisions 5,636,095 1,098 296,177 — 5,341,016 Other 42,578 — — — 42,578 Total $ 18,860,732 $ 6,203 $ 1,617,678 $ — $ 17,249,257 December 31, 2022 U.S. Treasury $ 5,450,546 $ — $ 398,959 $ — $ 5,051,587 Residential mortgage-backed securities 7,316,824 8,050 948,638 — 6,376,236 States and political subdivisions 7,098,635 9,108 334,388 — 6,773,355 Other 42,427 — — — 42,427 Total $ 19,908,432 $ 17,158 $ 1,681,985 $ — $ 18,243,605 All mortgage-backed securities included in the above table were issued by U.S. government agencies and corporations. At June 30, 2023, 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 74.3% are either guaranteed by the Texas Permanent School Fund (“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 $5.2 billion and $8.0 billion at June 30, 2023 and December 31, 2022, respectively. Accrued interest receivable on available-for-sale securities totaled $121.8 million and $140.6 million at June 30, 2023 and December 31, 2022, respectively, and is included in accrued interest receivable and other assets in the accompanying consolidated balance sheets. The table below summarizes, as of June 30, 2023, 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 $ 1,487,790 $ 58,237 $ 3,585,097 $ 325,531 $ 5,072,887 $ 383,768 Residential mortgage-backed securities 2,176,299 65,646 4,239,828 872,087 6,416,127 937,733 States and political subdivisions 3,391,385 45,640 1,543,520 250,537 4,934,905 296,177 Total $ 7,055,474 $ 169,523 $ 9,368,445 $ 1,448,155 $ 16,423,919 $ 1,617,678 As of June 30, 2023, 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 June 30, 2023. 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 $ — $ — $ 513,530 $ 752,288 $ 1,265,818 States and political subdivisions 59,282 14,024 37,558 2,313,305 2,424,169 Other — 1,500 — — 1,500 Total $ 59,282 $ 15,524 $ 551,088 $ 3,065,593 $ 3,691,487 Estimated Fair Value Residential mortgage-backed securities $ — $ — $ 450,850 $ 742,682 $ 1,193,532 States and political subdivisions 59,242 13,949 36,609 2,239,166 2,348,966 Other — 1,431 — — 1,431 Total $ 59,242 $ 15,380 $ 487,459 $ 2,981,848 $ 3,543,929 Available For Sale Amortized Cost U. S. Treasury $ 1,286,197 $ 2,542,538 $ 1,435,692 $ 192,229 $ 5,456,656 Residential mortgage-backed securities 310 4,985 15,986 7,704,122 7,725,403 States and political subdivisions 439,111 317,371 831,502 4,048,111 5,636,095 Other — — — — 42,578 Total $ 1,725,618 $ 2,864,894 $ 2,283,180 $ 11,944,462 $ 18,860,732 Estimated Fair Value U. S. Treasury $ 1,257,329 $ 2,420,131 $ 1,250,420 $ 145,008 $ 5,072,888 Residential mortgage-backed securities 305 4,865 15,898 6,771,707 6,792,775 States and political subdivisions 438,969 315,373 811,631 3,775,043 5,341,016 Other — — — — 42,578 Total $ 1,696,603 $ 2,740,369 $ 2,077,949 $ 10,691,758 $ 17,249,257 Sales of Securities. Sales of available for sale securities were as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Proceeds from sales $ 659,082 $ — $ 1,543,355 $ — Gross realized gains 561 — 5,417 — Gross realized losses (528) — (5,363) — Tax (expense) benefit of securities gains/losses (7) — (11) — Premiums and Discounts . Premium amortization and discount accretion included in interest income on securities was as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Premium amortization $ (21,242) $ (28,053) $ (47,167) $ (57,113) Discount accretion 4,843 2,482 10,248 3,888 Net (premium amortization) discount accretion $ (16,399) $ (25,571) $ (36,919) $ (53,225) Trading Account Securities. Trading account securities, at estimated fair value, were as follows: June 30, December 31, U.S. Treasury $ 27,546 $ 25,879 States and political subdivisions 4,971 2,166 Total $ 32,517 $ 28,045 Net gains and losses on trading account securities were as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Net gain on sales transactions $ 903 $ 1,012 $ 1,871 $ 1,352 Net mark-to-market gains (losses) (10) (76) (27) (244) Net gain (loss) on trading account securities $ 893 $ 936 $ 1,844 $ 1,108

Loans

Loans	6 Months Ended
	Jun. 30, 2023
Receivables [Abstract]
Loans	Loans Loans were as follows: June 30, December 31, Commercial and industrial $ 5,726,804 $ 5,674,798 Energy: Production 718,829 696,570 Service 138,816 133,542 Other 128,926 95,617 Total energy 986,571 925,729 Paycheck Protection Program 22,333 34,852 Commercial real estate: Commercial mortgages 6,389,649 6,168,910 Construction 1,468,071 1,477,247 Land 535,247 537,168 Total commercial real estate 8,392,967 8,183,325 Consumer real estate: Home equity lines of credit 730,557 691,841 Home equity loans 575,284 449,507 Home improvement loans 680,811 577,377 Other 171,264 124,814 Total consumer real estate 2,157,916 1,843,539 Total real estate 10,550,883 10,026,864 Consumer and other 459,720 492,726 Total loans $ 17,746,311 $ 17,154,969 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 June 30, 2023, there were no concentrations of loans related to any single industry in excess of 10% of total loans. At that date, the largest industry concentrations were related to the automobile dealerships industry, which totaled 6.0% of total loans and the energy industry, which totaled 5.6% of total loans. Unfunded commitments to extend credit and standby letters of credit issued to customers in the automobile dealership industry totaled $454.9 million and $20.1 million, respectively, as of June 30, 2023, while unfunded commitments to extend credit and standby letters of credit issued to customers in the energy industry totaled $1.0 billion and $84.1 million, respectively, as of June 30, 2023. 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 June 30, 2023 or December 31, 2022. 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 $389.2 million at June 30, 2023 and $391.3 million at December 31, 2022. Accrued Interest Receivable. Accrued interest receivable on loans totaled $73.9 million and $68.7 million at June 30, 2023 and December 31, 2022, respectively, and is included in accrued interest receivable and other assets in the accompanying 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: June 30, 2023 December 31, 2022 Total Non-Accrual Non-Accrual with No Credit Loss Allowance Total Non-Accrual Non-Accrual with No Credit Loss Allowance Commercial and industrial $ 22,217 $ 3,817 $ 18,130 $ 8,514 Energy 16,712 11,880 15,224 7,139 Commercial real estate: Buildings, land and other 25,682 6,617 3,552 1,991 Construction — — — — Consumer real estate 3,170 3,170 927 927 Consumer and other — — — — Total $ 67,781 $ 25,484 $ 37,833 $ 18,571 The following table presents non-accrual loans as of June 30, 2023 by class and year of origination. 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial and industrial $ — $ — $ 221 $ 754 $ 2,957 $ 1,172 $ 16,746 $ 367 $ 22,217 Energy 10,324 — — 59 1,349 2 4,832 146 16,712 Commercial real estate: Buildings, land and other 1,924 8 296 18,328 1,483 3,643 — — 25,682 Construction — — — — — — — — — Consumer real estate — — — 39 2,470 95 — 566 3,170 Consumer and other — — — — — — — — — Total $ 12,248 $ 8 $ 517 $ 19,180 $ 8,259 $ 4,912 $ 21,578 $ 1,079 $ 67,781 In the table above, energy and commercial real estate loans reported as 2023 originations as of June 30, 2023 were first originated in years prior to 2023 but were renewed in the current year. Had non-accrual loans performed in accordance with their original contract terms, we would have recognized additional interest income, net of tax, of approximately $835 thousand and $1.4 million for the three and six months ended June 30, 2023, respectively, and approximately $436 thousand and $843 thousand for the three and six months ended June 30, 2022, respectively. An age analysis of past due loans (including both accruing and non-accruing loans), segregated by class of loans, as of June 30, 2023 was as follows: Loans Loans Total Current Total Accruing Commercial and industrial $ 29,280 $ 5,224 $ 34,504 $ 5,692,300 $ 5,726,804 $ 3,025 Energy 2,224 6,386 8,610 977,961 986,571 — Paycheck Protection Program 80 2,725 2,805 19,528 22,333 2,725 Commercial real estate: Buildings, land and other 28,554 20,022 48,576 6,876,320 6,924,896 568 Construction 669 118 787 1,467,284 1,468,071 118 Consumer real estate 8,843 8,114 16,957 2,140,959 2,157,916 5,039 Consumer and other 5,153 336 5,489 454,231 459,720 336 Total $ 74,803 $ 42,925 $ 117,728 $ 17,628,583 $ 17,746,311 $ 11,811 Modifications to Borrowers Experiencing Financial Difficulty. From time to time, we may modify certain loans to borrowers who are experiencing financial difficulty. In some cases, these modifications may result in new loans. Loan modifications to borrowers experiencing financial difficulty may be in the form of a principal forgiveness, an interest rate reduction, an other-than-insignificant payment delay, or a term extension or a combination thereof, among other things. The period-end balance of loan modifications, segregated by type of modification, to borrowers experiencing financial difficulty during the six months ended June 30, 2023 and June 30, 2022 are set forth in the table below, regardless of whether such modifications resulted in a new loan. There were no commitments to lend additional funds to these borrowers at June 30, 2023. Payment Percent of Combination: Payment Delay and Term Extension Percent of June 30, 2023 Commercial and industrial $ — — % $ 16,020 0.3 % Commercial real estate: Buildings, land and other — — 20,466 0.3 $ — — $ 36,486 0.2 June 30, 2022 Commercial real estate: Buildings, land and other $ 1,116 — — — $ 1,116 — $ — — The financial effects of the loan modifications made to borrowers experiencing financial difficulty were not significant during the six months ended June 30, 2023. The loan modifications reported in the table above did not significantly impact our determination of the allowance for credit losses on loans during the six months ended June 30, 2023. Information as of or for the six months ended June 30, 2023 and June 30, 2022 related to loans modified (by type of modification) in the preceding twelve months, respectively, whereby the borrower was experiencing financial difficulty at the time of modification is set forth in the following table. June 30, 2023 June 30, 2022 Term Payment Combination: Payment Delay and Term Extension Term Payment Combination: Payment Delay and Term Extension Past due in excess of 90 days or on non-accrual status at period-end: Commercial and industrial $ — $ — $ 16,020 $ — $ — $ — Commercial real estate: Buildings, land and other — — 20,466 — 1,116 — $ — $ — $ 36,486 $ — $ 1,116 $ — Charge-offs during the period: Commercial real estate: Buildings, land and other $ — $ — $ — $ — $ 371 $ 352 Proceeds from sales: Commercial real estate: Buildings, land and other $ — $ — $ — $ — $ — $ 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 2022 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 table presents weighted-average risk grades for all commercial loans, by class and year of origination/renewal, as of June 30, 2023. Paycheck Protection Program (“PPP”) loans are excluded as such loans are fully guaranteed by the Small Business Administration (“SBA”). 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total W/A Risk Grade Commercial and industrial Risk grades 1-8 $ 1,113,216 $ 919,731 $ 524,735 $ 406,763 $ 186,103 $ 243,703 $ 2,026,310 $ 48,004 $ 5,468,565 6.29 Risk grade 9 17,610 17,339 32,116 3,745 2,307 10,869 40,715 5,203 129,904 9.00 Risk grade 10 9,988 510 622 396 4,165 744 19,268 564 36,257 10.00 Risk grade 11 4,491 4,164 4,001 8,747 16,121 1,523 19,749 11,065 69,861 11.00 Risk grade 12 — — 221 702 2,687 1,172 14,607 367 19,756 12.00 Risk grade 13 — — — 52 270 — 2,139 — 2,461 13.00 $ 1,145,305 $ 941,744 $ 561,695 $ 420,405 $ 211,653 $ 258,011 $ 2,122,788 $ 65,203 $ 5,726,804 6.46 W/A risk grade 6.31 6.76 7.10 5.93 6.57 6.17 6.31 7.66 6.46 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total W/A Risk Grade Energy Risk grades 1-8 $ 301,108 $ 65,831 $ 83,174 $ 4,240 $ 2,393 $ 5,297 $ 457,225 $ 33,858 $ 953,126 5.79 Risk grade 9 311 4,456 139 — 445 589 3,603 1,972 11,515 9.00 Risk grade 10 — — — — 355 189 — — 544 10.00 Risk grade 11 — — 106 170 3,101 12 1,285 — 4,674 11.00 Risk grade 12 10,324 — — 59 1,349 2 2,132 146 14,012 12.00 Risk grade 13 — — — — — — 2,700 — 2,700 13.00 $ 311,743 $ 70,287 $ 83,419 $ 4,469 $ 7,643 $ 6,089 $ 466,945 $ 35,976 $ 986,571 5.96 W/A risk grade 6.32 6.60 5.78 7.68 9.83 7.14 5.58 5.69 5.96 Commercial real estate: Buildings, land, other Risk grades 1-8 $ 699,039 $ 1,735,438 $ 1,421,130 $ 851,503 $ 570,561 $ 1,009,089 $ 150,060 $ 103,188 $ 6,540,008 6.97 Risk grade 9 9,069 15,323 10,729 40,843 70,271 27,324 1,980 1,214 176,753 9.00 Risk grade 10 491 29,583 7,991 4,086 1,754 3,796 — 2,646 50,347 10.00 Risk grade 11 7,653 6,163 48,496 8,477 — 57,948 2,993 376 132,106 11.00 Risk grade 12 1,924 8 296 17,178 1,483 3,493 — — 24,382 12.00 Risk grade 13 — — — 1,150 — 150 — — 1,300 13.00 $ 718,176 $ 1,786,515 $ 1,488,642 $ 923,237 $ 644,069 $ 1,101,800 $ 155,033 $ 107,424 $ 6,924,896 7.14 W/A risk grade 7.10 7.05 7.28 7.22 7.02 7.17 7.13 6.50 7.14 Construction Risk grades 1-8 $ 271,025 $ 523,461 $ 342,339 $ 49,547 $ 945 $ 1,666 $ 179,127 $ — $ 1,368,110 7.19 Risk grade 9 9,975 14,668 3,067 2,100 — — 3,291 — 33,101 9.00 Risk grade 10 18,297 — 7,347 — — — 9,126 — 34,770 10.00 Risk grade 11 — 31,972 118 — — — — — 32,090 11.00 Risk grade 12 — — — — — — — — — 12.00 Risk grade 13 — — — — — — — — — 13.00 $ 299,297 $ 570,101 $ 352,871 $ 51,647 $ 945 $ 1,666 $ 191,544 $ — $ 1,468,071 7.38 W/A risk grade 7.68 7.39 7.39 4.63 7.07 6.77 7.65 — 7.38 Total commercial real estate $ 1,017,473 $ 2,356,616 $ 1,841,513 $ 974,884 $ 645,014 $ 1,103,466 $ 346,577 $ 107,424 $ 8,392,967 7.18 W/A risk grade 7.27 7.13 7.30 7.09 7.02 7.17 7.41 6.50 7.18 In the table above, certain loans are reported as 2023 originations and have risk grades of 11 or higher. These loans were, for the most part, first originated in various years prior to 2023 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, 2022. Refer to our 2022 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 6.24 $ 5,435,917 5.44 $ 887,182 6.94 $ 6,340,028 7.04 $ 1,430,012 6.96 $ 7,770,040 Risk grade 9 9.00 146,192 9.00 11,112 9.00 189,928 9.00 34,952 9.00 224,880 Risk grade 10 10.00 37,596 10.00 642 10.00 91,020 10.00 931 10.00 91,951 Risk grade 11 11.00 36,963 11.00 11,569 11.00 81,550 11.00 11,352 11.00 92,902 Risk grade 12 12.00 12,521 12.00 10,840 12.00 2,957 12.00 — 12.00 2,957 Risk grade 13 13.00 5,609 13.00 4,384 13.00 595 13.00 — 13.00 595 Total 6.39 $ 5,674,798 5.67 $ 925,729 7.09 $ 6,706,078 7.12 $ 1,477,247 7.10 $ 8,183,325 Information about the payment status of consumer loans, segregated by portfolio segment and year of origination, as of June 30, 2023 was as follows: 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total Consumer real estate: Past due 30-89 days $ 297 $ 1,126 $ 1,075 $ 236 $ 480 $ 1,534 $ 3,861 $ 234 $ 8,843 Past due 90 or more days — 95 172 63 2,539 1,081 523 3,641 8,114 Total past due 297 1,221 1,247 299 3,019 2,615 4,384 3,875 16,957 Current loans 284,398 438,609 300,363 182,845 62,030 150,136 713,920 8,658 2,140,959 Total $ 284,695 $ 439,830 $ 301,610 $ 183,144 $ 65,049 $ 152,751 $ 718,304 $ 12,533 $ 2,157,916 Consumer and other: Past due 30-89 days $ 2,202 $ 316 $ 158 $ 12 $ 42 $ 49 $ 2,226 $ 148 $ 5,153 Past due 90 or more days 84 34 1 — — — 212 5 336 Total past due 2,286 350 159 12 42 49 2,438 153 5,489 Current loans 49,542 39,133 13,771 4,820 1,985 1,900 320,720 22,360 454,231 Total $ 51,828 $ 39,483 $ 13,930 $ 4,832 $ 2,027 $ 1,949 $ 323,158 $ 22,513 $ 459,720 Revolving loans that converted to term during the three and six months ended June 30, 2023 and 2022 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Commercial and industrial $ 3,835 $ 16,518 $ 14,606 $ 21,973 Energy — 247 2,567 247 Commercial real estate: Buildings, land and other 5,944 10,681 5,944 10,726 Construction — 13 — 4,248 Consumer real estate 1,064 888 1,743 1,684 Consumer and other 1,669 1,792 3,671 5,868 Total $ 12,512 $ 30,139 $ 28,531 $ 44,746 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 2022 Form 10-K, totaled 127.7 at June 30, 2023 and 130.3 at December 31, 2022. 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 2022 Form 10-K. During the first quarter of 2023, we recalibrated and updated all of our commercial loan models, with the exception of the models related to commercial real estate - non-owner occupied loans, as well as our consumer real estate loan models. While the fundamental modeling methodologies remain unchanged, the updates included (i) separating the energy loan pool from the commercial and industrial pool as a result of differences in loss characteristics observed in recent history and (ii) changing the modeling approach related to loan renewals whereby each renewal is treated as a separate loan which impacted loan life assumptions. For modeling purposes, our loan pools now include (i) commercial and industrial non-revolving, (ii) commercial and industrial revolving, (iii) energy, (iv) commercial real estate - owner occupied, (v) commercial real estate - non-owner occupied, (vi) commercial real estate - construction/land development, (vii) consumer real estate and (viii) consumer and other. The overall approximate impact of the model updates during the first quarter was a $45.0 million decrease in modeled expected credit losses on loans though the impact of this decrease was largely offset with qualitative adjustments. The decrease in modeled expected credit losses on loans was largely driven by lower measurements for probability of default (“PD”) and loss given default (“LGD”) based on the historical data series (2008 through 2018) used for the recalibration. This period was one of relatively low losses and included higher levels of government stimulus. The lower PD and LGD measurements were also impacted by shorter loan life assumptions due to the aforementioned change in the modeling approach related to loan renewals. The following table presents details of the allowance for credit losses on loans segregated by loan portfolio segment as of June 30, 2023 and December 31, 2022. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA. June 30, 2023 Commercial Energy Commercial Consumer Consumer Total Modeled expected credit losses $ 46,435 $ 5,733 $ 15,496 $ 12,594 $ 5,511 $ 85,769 Q-Factor and other qualitative adjustments 26,270 6,496 104,130 441 4,052 141,389 Specific allocations 2,461 2,700 1,300 — — 6,461 Total $ 75,166 $ 14,929 $ 120,926 $ 13,035 $ 9,563 $ 233,619 December 31, 2022 Modeled expected credit losses $ 61,918 $ 8,531 $ 27,013 $ 7,847 $ 4,983 $ 110,292 Q-Factor and other qualitative adjustments 36,237 5,148 61,572 157 2,034 105,148 Specific allocations 6,082 4,383 1,716 — — 12,181 Total $ 104,237 $ 18,062 $ 90,301 $ 8,004 $ 7,017 $ 227,621 The following table details activity in the allowance for credit losses on loans by portfolio segment for the three and six months ended June 30, 2023 and 2022. 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: June 30, 2023 Beginning balance $ 78,465 $ 19,191 $ 115,693 $ 9,708 $ 8,457 $ 231,514 Credit loss expense (benefit) 2,404 (4,433) 5,133 3,822 5,007 11,933 Charge-offs (7,136) (518) — (1,080) (7,016) (15,750) Recoveries 1,433 689 100 585 3,115 5,922 Net (charge-offs) recoveries (5,703) 171 100 (495) (3,901) (9,828) Ending balance $ 75,166 $ 14,929 $ 120,926 $ 13,035 $ 9,563 $ 233,619 June 30, 2022 Beginning balance $ 87,026 $ 15,422 $ 128,954 $ 6,359 $ 9,074 $ 246,835 Credit loss expense (benefit) 942 427 (12,232) 583 5,884 (4,396) Charge-offs (1,891) — — (131) (5,322) (7,344) Recoveries 1,193 418 384 43 2,499 4,537 Net (charge-offs) recoveries (698) 418 384 (88) (2,823) (2,807) Ending balance $ 87,270 $ 16,267 $ 117,106 $ 6,854 $ 12,135 $ 239,632 Commercial Energy Commercial Consumer Consumer Total Six months ended: June 30, 2023 Beginning balance $ 104,237 $ 18,062 $ 90,301 $ 8,004 $ 7,017 $ 227,621 Credit loss expense (benefit) (18,280) (3,467) 30,494 5,105 10,756 24,608 Charge-offs (13,316) (518) — (1,330) (13,958) (29,122) Recoveries 2,525 852 131 1,256 5,748 10,512 Net (charge-offs) recoveries (10,791) 334 131 (74) (8,210) (18,610) Ending balance $ 75,166 $ 14,929 $ 120,926 $ 13,035 $ 9,563 $ 233,619 June 30, 2022 Beginning balance $ 72,091 $ 17,217 $ 144,936 $ 6,585 $ 7,837 $ 248,666 Credit loss expense (benefit) 18,503 (1,617) (27,841) 557 10,466 68 Charge-offs (5,346) (371) (702) (362) (11,093) (17,874) Recoveries 2,022 1,038 713 74 4,925 8,772 Net (charge-offs) recoveries (3,324) 667 11 (288) (6,168) (9,102) Ending balance $ 87,270 $ 16,267 $ 117,106 $ 6,854 $ 12,135 $ 239,632 The following table presents year-to-date gross charge-offs by year of origination as of June 30, 2023. 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial and industrial $ 124 $ 208 $ 178 $ 55 $ 25 $ 29 $ 7,427 $ 5,270 $ 13,316 Energy — — — — — — — 518 518 Commercial real estate: Buildings, land and other — — — — — — — — — Construction — — — — — — — — — Consumer real estate — — 280 — — 89 961 — 1,330 Consumer and other 8,143 4,354 57 12 — 23 1,051 318 13,958 Total $ 8,267 $ 4,562 $ 515 $ 67 $ 25 $ 141 $ 9,439 $ 6,106 $ 29,122 In the table above, $8.1 million of the consumer and other loan charge-offs reported as 2023 originations and $4.2 million of the total reported as 2022 originations were related to deposit overdrafts. 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 June 30, 2023 and December 31, 2022. June 30, 2023 December 31, 2022 Loan Specific Allocations Loan Specific Allocations Commercial and industrial $ 20,862 $ 2,461 $ 18,980 $ 6,082 Energy 16,445 2,700 15,058 4,383 Paycheck Protection Program — — — — Commercial real estate: Buildings, land and other 24,954 1,300 17,711 1,716 Construction — — — — Consumer real estate 3,030 — 827 — Consumer and other — — — — Total $ 65,291 $ 6,461 $ 52,576 $ 12,181

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	6 Months Ended
	Jun. 30, 2023
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. June 30, December 31, Goodwill $ 654,952 $ 654,952 Other intangible assets: Core deposits $ 155 $ 310 Customer relationships 53 76 $ 208 $ 386 The estimated aggregate future amortization expense for intangible assets remaining as of June 30, 2023 is as follows: Remainder of 2023 $ 105 2024 87 2025 11 2026 5 $ 208

Deposits

Deposits	6 Months Ended
	Jun. 30, 2023
Disclosure Text Block [Abstract]
Deposits	Deposits Deposits were as follows: June 30, December 31, Non-interest-bearing demand deposits $ 14,904,614 $ 17,598,234 Interest-bearing deposits: Savings and interest checking 10,540,458 12,333,675 Money market accounts 11,026,368 12,227,247 Time accounts 4,229,390 1,795,040 Total interest-bearing deposits 25,796,216 26,355,962 Total deposits $ 40,700,830 $ 43,954,196 The table below presents additional information about our deposits. Public funds in excess of deposit insurance limits are included in the totals for deposits not covered by insurance; however, such deposits are generally fully collateralized by securities. June 30, December 31, Deposits from foreign sources (primarily Mexico) $ 1,036,777 $ 1,048,943 Non-interest-bearing public funds deposits 447,194 788,040 Interest-bearing public funds deposits 696,521 758,761 Total deposits not covered by deposit insurance 20,630,167 23,839,797 Time deposits not covered by deposit insurance 1,670,388 430,128

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2023
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 2022 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: June 30, December 31, Commitments to extend credit $ 12,208,032 $ 12,137,957 Standby letters of credit 405,900 383,851 Deferred standby letter of credit fees 2,176 2,236 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 2022 Form 10-K. This methodology was also impacted by the model updates during the first quarter of 2023 as described in Note 3 - Loans. The overall approximate impact of the model updates was a $19.0 million decrease in modeled expected credit losses for off-balance-sheet credit exposures, though the impact of this decrease was largely offset with qualitative adjustments. The following table details activity in the allowance for credit losses on off-balance-sheet credit exposures. Three Months Ended Six Months Ended 2023 2022 2023 2022 Beginning balance $ 54,918 $ 45,850 $ 58,593 $ 50,314 Credit loss expense (benefit) (2,037) 4,396 (5,712) (68) Ending balance $ 52,881 $ 50,246 $ 52,881 $ 50,246 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 Six Months Ended 2023 2022 2023 2022 Amortization of lease right-of-use assets $ 8,747 $ 8,209 $ 17,512 $ 16,314 Short-term lease expense 493 490 902 1,103 Non-lease components (including taxes, insurance, common maintenance, etc.) 3,662 2,748 7,043 5,768 Total $ 12,902 $ 11,447 $ 25,457 $ 23,185 Right-of-use lease assets totaled $286.5 million at June 30, 2023 and $288.8 million at December 31, 2022 and are reported as a component of premises and equipment on our accompanying consolidated balance sheets. The related lease liabilities totaled $320.6 million at June 30, 2023 and $321.9 million at December 31, 2022 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 $16.6 million during the three and six months ended June 30, 2023, respectively, and $8.4 million and $16.4 million during the three and six months ended June 30, 2022, respectively. There has been no significant change in our expected future minimum lease payments since December 31, 2022. See the 2022 Form 10-K for information regarding these commitments.

Capital and Regulatory Matters

Capital and Regulatory Matters	6 Months Ended
	Jun. 30, 2023
Banking Regulation, Common Equity Tier 1 Risk-Based Capital [Abstract]
Capital and Regulatory Matters	Capital and Regulatory MattersBanks 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 2022 Form 10-K. This CECL transitional adjustment totaled $30.8 million and $46.2 million at June 30, 2023 and December 31, 2022, 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 June 30, 2023 and December 31, 2022, the details of which are further discussed below. Frost Bank did not have any additional Tier 1 capital beyond Common Equity Tier 1 at June 30, 2023 or December 31, 2022. 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 The following table presents actual and required capital ratios as of June 30, 2023 and December 31, 2022 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 2022 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 June 30, 2023 Common Equity Tier 1 to Risk-Weighted Assets Cullen/Frost $ 3,943,110 13.42 % $ 2,056,052 7.00 % N/A N/A Frost Bank 3,973,809 13.55 2,053,467 7.00 $ 1,906,791 6.50 % Tier 1 Capital to Risk-Weighted Assets Cullen/Frost 4,088,562 13.92 2,496,634 8.50 1,762,330 6.00 Frost Bank 3,973,809 13.55 2,493,496 8.50 2,346,820 8.00 Total Capital to Risk-Weighted Assets Cullen/Frost 4,520,634 15.39 3,084,077 10.50 2,937,217 10.00 Frost Bank 4,225,881 14.41 3,080,201 10.50 2,933,525 10.00 Leverage Ratio Cullen/Frost 4,088,562 8.11 2,016,414 4.00 N/A N/A Frost Bank 3,973,809 7.88 2,015,896 4.00 2,519,870 5.00 December 31, 2022 Common Equity Tier 1 to Risk-Weighted Assets Cullen/Frost $ 3,751,200 12.85 % $ 2,042,876 7.00 % N/A N/A Frost Bank 3,789,056 13.00 2,040,388 7.00 $ 1,894,646 6.50 % Tier 1 Capital to Risk-Weighted Assets Cullen/Frost 3,896,652 13.35 2,480,635 8.50 1,751,036 6.00 Frost Bank 3,789,056 13.00 2,477,614 8.50 2,331,872 8.00 Total Capital to Risk-Weighted Assets Cullen/Frost 4,330,982 14.84 3,064,313 10.50 2,918,394 10.00 Frost Bank 4,023,386 13.80 3,060,583 10.50 2,914,841 10.00 Leverage Ratio Cullen/Frost 3,896,652 7.29 2,136,680 4.00 N/A N/A Frost Bank 3,789,056 7.09 2,136,316 4.00 2,670,395 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 June 30, 2023, 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 June 30, 2023 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 June 30, 2023, 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 2022 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 25, 2023, 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 June 30, 2023, Frost Bank could pay aggregate dividends of up to $967.6 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. Under the terms of the Series B Preferred Stock, in the event that we do not declare and pay dividends on the Series B Preferred Stock for the most recent dividend period, we may not, with certain exceptions, declare or pay dividends on, or purchase, redeem or otherwise acquire, shares of our common stock or any of our securities that rank junior to the Series B Preferred Stock.

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Jun. 30, 2023
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 various interest rate swaps, caps and floors, among other things, 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 2022 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 June 30, 2023 and December 31, 2022. June 30, 2023 December 31, 2022 Notional Estimated Notional Estimated Derivatives designated as hedges of fair value: Financial institution counterparties: Loan/lease interest rate swaps – assets $ — $ — $ 1,614 $ 19 Non-hedging interest rate derivatives: Financial institution counterparties: Loan/lease interest rate swaps – assets 1,162,694 78,404 1,165,812 70,416 Loan/lease interest rate swaps – liabilities 72,833 (1,332) 78,798 (1,102) Loan/lease interest rate caps – assets 229,804 14,557 246,442 15,256 Customer counterparties: Loan/lease interest rate swaps – assets 78,789 1,401 53,570 1,102 Loan/lease interest rate swaps – liabilities 1,156,738 (78,402) 1,175,563 (79,175) Loan/lease interest rate caps – liabilities 229,804 (14,557) 246,442 (15,256) The weighted-average rates paid and received for interest rate swaps outstanding at June 30, 2023 were as follows: Weighted-Average Interest Interest Interest rate swaps: Non-hedging interest rate swaps – financial institution counterparties 3.96 % 5.62 % Non-hedging interest rate swaps – customer counterparties 5.62 3.96 The weighted-average strike rate for outstanding interest rate caps was 3.32% at June 30, 2023. 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. June 30, 2023 December 31, 2022 Notional Notional Estimated Notional Estimated Financial institution counterparties: Oil – assets Barrels 4,134 $ 30,701 4,024 $ 27,082 Oil – liabilities Barrels 5,345 (21,229) 6,068 (53,579) Natural gas – assets MMBTUs 16,694 6,668 16,539 6,220 Natural gas – liabilities MMBTUs 9,871 (6,841) 15,682 (19,138) Customer counterparties: Oil – assets Barrels 5,391 21,580 6,068 54,219 Oil – liabilities Barrels 4,088 (30,255) 4,024 (26,551) Natural gas – assets MMBTUs 9,871 6,865 15,682 19,164 Natural gas – liabilities MMBTUs 16,694 (6,477) 16,539 (6,124) 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 are presented in the following table. June 30, 2023 December 31, 2022 Notional Notional Estimated Notional Estimated Financial institution counterparties: Forward and option contracts – assets EUR — $ — 875 $ 1 Forward and option contracts – liabilities EUR — — 875 (10) Customer counterparties: Forward and option contracts – assets EUR — — 875 10 Forward and option contracts – liabilities EUR — — 875 (1) 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 Six Months Ended 2023 2022 2023 2022 Commercial loan/lease interest rate swaps: Amount of gain (loss) included in interest income on loans $ 4 $ (5) $ 16 $ (18) Amount of (gain) loss included in other non-interest expense 4 3 4 5 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 Six Months Ended 2023 2022 2023 2022 Non-hedging interest rate derivatives: Other non-interest income $ 1,002 $ 515 $ 1,712 $ 1,031 Other non-interest expense 1 — — — Non-hedging commodity derivatives: Other non-interest income 503 649 925 1,578 Non-hedging foreign currency derivatives: Other non-interest income — 45 25 63 Counterparty Credit Risk. Our credit exposure relating to interest rate, commodity and foreign currency derivative contracts with bank customers was approximately $6.8 million at June 30, 2023. 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, commodity and foreign currency derivative contracts with upstream financial institution counterparties was approximately $341 thousand at June 30, 2023. This amount was primarily related to a shortfall of collateral. Collateral positions are 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

Balance Sheet Offsetting

Balance Sheet Offsetting	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023 is presented in the following tables. Gross Amount Gross Amount Net Amount June 30, 2023 Financial assets: Derivatives: Interest rate contracts $ 92,961 $ — $ 92,961 Commodity contracts 37,369 — 37,369 Total derivatives 130,330 — 130,330 Resell agreements 84,650 — 84,650 Total $ 214,980 $ — $ 214,980 Financial liabilities: Derivatives: Interest rate contracts $ 1,332 $ — $ 1,332 Commodity contracts 28,070 — 28,070 Total derivatives 29,402 — 29,402 Repurchase agreements 3,569,870 — 3,569,870 Total $ 3,599,272 $ — $ 3,599,272 Gross Amounts Not Offset Net Amount Financial Collateral Net June 30, 2023 Financial assets: Derivatives: Counterparty B $ 32,143 $ (9,548) $ (22,595) $ — Counterparty E 16,312 (896) (15,240) 176 Counterparty F 18,387 (8,839) (9,463) 85 Counterparty G 10,484 — (10,430) 54 Other counterparties 53,004 (10,119) (42,861) 24 Total derivatives 130,330 (29,402) (100,589) 339 Resell agreements 84,650 — (84,650) — Total $ 214,980 $ (29,402) $ (185,239) $ 339 Financial liabilities: Derivatives: Counterparty B $ 9,548 $ (9,548) $ — $ — Counterparty E 896 (896) — — Counterparty F 8,839 (8,839) — — Other counterparties 10,119 (10,119) — — Total derivatives 29,402 (29,402) — — Repurchase agreements 3,569,870 — (3,569,870) — Total $ 3,599,272 $ (29,402) $ (3,569,870) $ — Information about financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2022 is presented in the following tables. Gross Amount Gross Amount Net Amount December 31, 2022 Financial assets: Derivatives: Interest rate contracts $ 85,691 $ — $ 85,691 Commodity contracts 33,302 — 33,302 Foreign currency contracts 1 — 1 Total derivatives 118,994 — 118,994 Resell agreements 87,150 — 87,150 Total $ 206,144 $ — $ 206,144 Financial liabilities: Derivatives: Interest rate contracts $ 1,102 $ — $ 1,102 Commodity contracts 72,717 — 72,717 Foreign currency contracts 10 — 10 Total derivatives 73,829 — 73,829 Repurchase agreements 4,660,641 — 4,660,641 Total $ 4,734,470 $ — $ 4,734,470 Gross Amounts Not Offset Net Amount Financial Collateral Net December 31, 2022 Financial assets: Derivatives: Counterparty B $ 39,370 $ (24,500) $ (14,870) $ — Counterparty E 14,430 (47) (14,131) 252 Counterparty F 17,297 (17,297) — — Counterparty G 10,660 — (10,660) — Other counterparties 37,237 (20,684) (16,307) 246 Total derivatives 118,994 (62,528) (55,968) 498 Resell agreements 87,150 — (87,150) — Total $ 206,144 $ (62,528) $ (143,118) $ 498 Financial liabilities: Derivatives: Counterparty B $ 24,500 $ (24,500) $ — $ — Counterparty E 47 (47) — — Counterparty F 27,747 (17,297) (8,479) 1,971 Counterparty G — — — — Other counterparties 21,535 (20,684) (851) — Total derivatives 73,829 (62,528) (9,330) 1,971 Repurchase agreements 4,660,641 — (4,660,641) — Total $ 4,734,470 $ (62,528) $ (4,669,971) $ 1,971 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 June 30, 2023 and December 31, 2022 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 June 30, 2023 Repurchase agreements: U.S. Treasury $ 2,716,439 $ — $ — $ — $ 2,716,439 Residential mortgage-backed securities 853,431 — — — 853,431 Total borrowings $ 3,569,870 $ — $ — $ — $ 3,569,870 Gross amount of recognized liabilities for repurchase agreements $ 3,569,870 Amounts related to agreements not included in offsetting disclosures above $ — December 31, 2022 Repurchase agreements: U.S. Treasury $ 3,735,061 $ — $ — $ — $ 3,735,061 Residential mortgage-backed securities 925,580 — — — 925,580 Total borrowings $ 4,660,641 $ — $ — $ — $ 4,660,641 Gross amount of recognized liabilities for repurchase agreements $ 4,660,641 Amounts related to agreements not included in offsetting disclosures above $ —

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023, there were 514,028 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, 2023 45,661 $ 87.15 465,319 $ 105.36 213,749 $ 96.20 616,227 $ 71.27 Granted 8,503 103.47 2,594 128.42 — — — — Exercised/vested — — (1,957) 91.96 (28,151) 85.74 (33,905) 72.13 Forfeited/expired — — (1,415) 116.02 (18,254) 85.74 — — Balance, June 30, 2023 54,164 89.71 464,541 105.52 167,344 99.10 582,322 71.22 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 Six Months Ended 2023 2022 2023 2022 New shares issued from available authorized shares — — 49,887 — Shares issued from available treasury stock 13,626 28,832 14,126 144,262 Proceeds from stock option exercises $ 946 $ 751 $ 2,446 $ 6,490 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 Six Months Ended 2023 2022 2023 2022 Non-vested stock units $ 2,864 $ 2,291 $ 6,171 $ 4,649 Deferred stock units 880 720 880 720 Performance stock units 1,049 407 2,484 161 Total $ 4,793 $ 3,418 $ 9,535 $ 5,530 Income tax benefit $ 800 $ 612 $ 1,868 $ 1,320 Unrecognized stock-based compensation expense at June 30, 2023 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 $ 15,768 Performance stock units 7,029 Total $ 22,797

Earnings Per Common Share

Earnings Per Common Share	6 Months Ended
	Jun. 30, 2023
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 2022 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 Six Months Ended 2023 2022 2023 2022 Net income $ 162,118 $ 119,114 $ 339,771 $ 218,216 Less: Preferred stock dividends 1,669 1,669 3,338 3,338 Net income available to common shareholders 160,449 117,445 336,433 214,878 Less: Earnings allocated to participating securities 1,645 1,036 3,468 1,888 Net earnings allocated to common stock $ 158,804 $ 116,409 $ 332,965 $ 212,990 Distributed earnings allocated to common stock $ 55,783 $ 48,092 $ 111,789 $ 96,143 Undistributed earnings allocated to common stock 103,021 68,317 221,176 116,847 Net earnings allocated to common stock $ 158,804 $ 116,409 $ 332,965 $ 212,990 Weighted-average shares outstanding for basic earnings per common share 64,240,789 64,112,828 64,306,809 64,082,185 Dilutive effect of stock compensation 187,172 354,401 225,267 382,395 Weighted-average shares outstanding for diluted earnings per common share 64,427,961 64,467,229 64,532,076 64,464,580

Defined Benefit Plans

Defined Benefit Plans	6 Months Ended
	Jun. 30, 2023
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 Six Months Ended 2023 2022 2023 2022 Expected return on plan assets, net of expenses $ (2,740) $ (3,492) $ (5,480) $ (6,983) Interest cost on projected benefit obligation 1,746 1,004 3,492 2,008 Net amortization and deferral 870 741 1,740 1,482 Net periodic expense (benefit) $ (124) $ (1,747) $ (248) $ (3,493) Our non-qualified defined benefit pension plan is not funded. No contributions to the qualified defined benefit pension plan were made during the six months ended June 30, 2023. We do not expect to make any contributions to the qualified defined benefit plan during the remainder of 2023.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income tax expense was as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Current income tax expense $ 32,413 $ 22,646 $ 67,408 $ 35,705 Deferred income tax expense (benefit) (680) (1,972) (2,489) (2,404) Income tax expense, as reported $ 31,733 $ 20,674 $ 64,919 $ 33,301 Effective tax rate 16.4 % 14.8 % 16.0 % 13.2 % We had a net deferred tax asset totaling $365.4 million at June 30, 2023 and $374.4 million at December 31, 2022. No valuation allowance for deferred tax assets was recorded at June 30, 2023 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 securities, loans and life insurance policies and the income tax effects associated with stock-based compensation, among other things. 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 2019.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2023
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 $ (206,863) $ (43,441) $ (163,422) $ (636,523) $ (133,670) $ (502,853) Change in net unrealized gain on securities transferred to held to maturity (162) (34) (128) (189) (40) (149) Reclassification adjustment for net (gains) losses included in net income (33) (7) (26) — — — Total securities available for sale and transferred securities (207,058) (43,482) (163,576) (636,712) (133,710) (503,002) 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) 870 183 687 741 155 586 Total defined-benefit post-retirement benefit plans 870 183 687 741 155 586 Total other comprehensive income (loss) $ (206,188) $ (43,299) $ (162,889) $ (635,971) $ (133,555) $ (502,416) Six Months Ended Six 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 $ 53,406 $ 11,215 $ 42,191 $ (1,547,318) $ (324,937) $ (1,222,381) Change in net unrealized gain on securities transferred to held to maturity (322) (67) (255) (398) (84) (314) Reclassification adjustment for net (gains) losses included in net income (54) (11) (43) — — — Total securities available for sale and transferred securities 53,030 11,137 41,893 (1,547,716) (325,021) (1,222,695) 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) 1,740 366 1,374 1,482 311 1,171 Total defined-benefit post-retirement benefit plans 1,740 366 1,374 1,482 311 1,171 Total other comprehensive income (loss) $ 54,770 $ 11,503 $ 43,267 $ (1,546,234) $ (324,710) $ (1,221,524) Activity in accumulated other comprehensive income (loss), net of tax, was as follows: Securities Defined Accumulated Balance at January 1, 2023 $ (1,313,791) $ (34,503) $ (1,348,294) Other comprehensive income (loss) before reclassifications 41,936 — 41,936 Reclassification of amounts included in net income (43) 1,374 1,331 Net other comprehensive income (loss) during period 41,893 1,374 43,267 Balance at June 30, 2023 $ (1,271,898) $ (33,129) $ (1,305,027) Balance at January 1, 2022 $ 380,209 $ (32,891) $ 347,318 Other comprehensive income (loss) before reclassifications (1,222,695) — (1,222,695) Reclassification of amounts included in net income — 1,171 1,171 Net other comprehensive income (loss) during period (1,222,695) 1,171 (1,221,524) Balance at June 30, 2022 $ (842,486) $ (31,720) $ (874,206)

Operating Segments

Operating Segments	6 Months Ended
	Jun. 30, 2023
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 2022 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: June 30, 2023 Net interest income (expense) $ 385,720 $ 2,090 $ (2,544) $ 385,266 Credit loss expense 9,901 — — 9,901 Non-interest income 57,808 46,147 (427) 103,528 Non-interest expense 246,927 35,558 2,557 285,042 Income (loss) before income taxes 186,700 12,679 (5,528) 193,851 Income tax expense (benefit) 30,636 2,663 (1,566) 31,733 Net income (loss) 156,064 10,016 (3,962) 162,118 Preferred stock dividends — — 1,669 1,669 Net income (loss) available to common shareholders $ 156,064 $ 10,016 $ (5,631) $ 160,449 Revenues from (expenses to) external customers $ 443,528 $ 48,237 $ (2,971) $ 488,794 June 30, 2022 Net interest income (expense) $ 289,186 $ 958 $ (1,936) $ 288,208 Credit loss expense (benefit) 1 (1) — — Non-interest income 55,397 43,054 (524) 97,927 Non-interest expense 211,044 33,158 2,145 246,347 Income (loss) before income taxes 133,538 10,855 (4,605) 139,788 Income tax expense (benefit) 19,821 2,279 (1,426) 20,674 Net income (loss) 113,717 8,576 (3,179) 119,114 Preferred stock dividends — — 1,669 1,669 Net income (loss) available to common shareholders $ 113,717 $ 8,576 $ (4,848) $ 117,445 Revenues from (expenses to) external customers $ 344,583 $ 44,012 $ (2,460) $ 386,135 Banking Frost Wealth Non-Banks Consolidated Six months ended: June 30, 2023 Net interest income (expense) $ 785,857 $ 3,744 $ (4,515) $ 785,086 Credit loss expense (benefit) 19,003 2 — 19,005 Non-interest income 121,451 88,185 (843) 208,793 Non-interest expense 496,794 69,505 3,885 570,184 Income (loss) before income taxes 391,511 22,422 (9,243) 404,690 Income tax expense (benefit) 62,754 4,709 (2,544) 64,919 Net income (loss) 328,757 17,713 (6,699) 339,771 Preferred stock dividends — — 3,338 3,338 Net income (loss) available to common shareholders $ 328,757 $ 17,713 $ (10,037) $ 336,433 Revenues from (expenses to) external customers $ 907,308 $ 91,929 $ (5,358) $ 993,879 June 30, 2022 Net interest income (expense) $ 539,305 $ 1,658 $ (3,684) $ 537,279 Credit loss expense — — — — Non-interest income 114,103 86,283 (1,069) 199,317 Non-interest expense 417,582 64,068 3,429 485,079 Income (loss) before income taxes 235,826 23,873 (8,182) 251,517 Income tax expense (benefit) 30,835 5,013 (2,547) 33,301 Net income (loss) 204,991 18,860 (5,635) 218,216 Preferred stock dividends — — 3,338 3,338 Net income (loss) available to common shareholders $ 204,991 $ 18,860 $ (8,973) $ 214,878 Revenues from (expenses to) external customers $ 653,408 $ 87,941 $ (4,753) $ 736,596

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2023
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 2022 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 June 30, 2023 and December 31, 2022, 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 June 30, 2023 Securities available for sale: U.S. Treasury $ 5,072,888 $ — $ — $ 5,072,888 Residential mortgage-backed securities — 6,792,775 — 6,792,775 States and political subdivisions — 5,341,016 — 5,341,016 Other — 42,578 — 42,578 Trading account securities: U.S. Treasury 27,546 — — 27,546 States and political subdivisions — 4,971 — 4,971 Derivative assets: Interest rate swaps, caps and floors — 94,362 — 94,362 Commodity swaps and options — 65,814 — 65,814 Derivative liabilities: Interest rate swaps, caps and floors — 94,291 — 94,291 Commodity swaps and options — 64,802 — 64,802 December 31, 2022 Securities available for sale: U.S. Treasury $ 5,051,587 $ — $ — $ 5,051,587 Residential mortgage-backed securities — 6,376,236 — 6,376,236 States and political subdivisions — 6,773,355 — 6,773,355 Other — 42,427 — 42,427 Trading account securities: U.S. Treasury 25,879 — — 25,879 States and political subdivisions — 2,166 — 2,166 Derivative assets: Interest rate swaps, caps and floors — 86,793 — 86,793 Commodity swaps and options — 106,685 — 106,685 Foreign currency forward contracts 11 — — 11 Derivative liabilities: Interest rate swaps, caps and floors — 95,533 — 95,533 Commodity swaps and options — 105,392 — 105,392 Foreign currency forward contracts 11 — — 11 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. Six Months Ended Six Months Ended Level 2 Level 3 Level 2 Level 3 Carrying value before allocations $ 19,064 $ 20,171 $ 5,454 $ 3,614 Specific (allocations) reversals of prior allocations (1,300) (2,100) (1,327) 6,877 Fair value $ 17,764 $ 18,071 $ 4,127 $ 10,491 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: June 30, 2023 December 31, 2022 Carrying Estimated Carrying Estimated Financial assets: Level 2 inputs: Cash and cash equivalents $ 7,107,336 $ 7,107,336 $ 12,028,132 $ 12,028,132 Securities held to maturity 3,691,220 3,543,929 2,639,083 2,467,865 Cash surrender value of life insurance policies 190,575 190,575 190,188 190,188 Accrued interest receivable 236,967 236,967 243,682 243,682 Level 3 inputs: Loans, net 17,512,692 16,933,702 16,927,348 16,343,417 Financial liabilities: Level 2 inputs: Deposits 40,700,830 40,683,556 43,954,196 43,920,741 Federal funds purchased 13,525 13,525 51,650 51,650 Repurchase agreements 3,569,870 3,569,870 4,660,641 4,660,641 Junior subordinated deferrable interest debentures 123,098 123,712 123,069 123,712 Subordinated notes 99,413 94,571 99,335 97,014 Accrued interest payable 40,523 40,523 18,444 18,444 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	6 Months Ended
	Jun. 30, 2023
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 2022 Form 10-K for additional information related to previously issued accounting standards updates. 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 became effective for us on January 1, 2023. See Note 3 - Loans for the new financial statement disclosures applicable under this update. ASU 2023-01, “Leases (Topic 842): Common Control Arrangements.” ASU 2023-01 requires entities to amortize leasehold improvements associated with common control leases over the useful life to the common control group. ASU 2023-01 also provides certain practical expedients applicable to private companies and not-for-profit organizations. ASU 2023-01 will be effective for us on January 1, 2024, though early adoption is permitted, and its adoption is not expected to have a significant effect on our financial statements. ASU No. 2023-02, “Investments—Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method.” ASU 2023-02 is intended to improve the accounting and disclosures for investments in tax credit structures. ASU 2023-02 allows entities to elect to account for qualifying tax equity investments using the proportional amortization method, regardless of the program giving rise to the related income tax credits. Previously, this method was only available for qualifying tax equity investments in low-income housing tax credit structures. ASU 2023-02 will be effective for us on January 1, 2024, though early adoption is permitted, and its adoption is not expected to have a significant effect on our financial statements. ASU No. 2023-03, “Presentation of Financial Statements (Topic 205), Income Statement—Reporting Comprehensive Income (Topic 220), Distinguishing Liabilities from Equity (Topic 480), Equity (Topic 505), and Compensation—Stock Compensation (Topic 718): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 120, SEC Staff Announcement at the March 24, 2022 EITF Meeting, and Staff Accounting Bulletin Topic 6.B, Accounting Series Release 280—General Revision of Regulation S-X: Income or Loss Applicable to Common Stock.” ASU 2023-03 amends the ASC for SEC updates pursuant to SEC Staff Accounting Bulletin No. 120; SEC Staff Announcement at the March 24, 2022 Emerging Issues Task Force (“EITF”) Meeting; and Staff Accounting Bulletin Topic 6.B, Accounting Series Release 280 - General Revision of Regulation S-X: Income or Loss Applicable to Common Stock. These updates were immediately effective and did not have a significant impact on our financial statements.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2023
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, 2022, included in our Annual Report on Form 10-K filed with the SEC on February 3, 2023 (the “ 2022 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)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Financing Receivable, Allowance for Credit Losses, Policy for Uncollectible Amounts	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 2022 Form 10-K. During the first quarter of 2023, we recalibrated and updated all of our commercial loan models, with the exception of the models related to commercial real estate - non-owner occupied loans, as well as our consumer real estate loan models. While the fundamental modeling methodologies remain unchanged, the updates included (i) separating the energy loan pool from the commercial and industrial pool as a result of differences in loss characteristics observed in recent history and (ii) changing the modeling approach related to loan renewals whereby each renewal is treated as a separate loan which impacted loan life assumptions. For modeling purposes, our loan pools now include (i) commercial and industrial non-revolving, (ii) commercial and industrial revolving, (iii) energy, (iv) commercial real estate - owner occupied, (v) commercial real estate - non-owner occupied, (vi) commercial real estate - construction/land development, (vii) consumer real estate and (viii) consumer and other. The overall approximate impact of the model updates during the first quarter was a $45.0 million decrease in modeled expected

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2023
Accounting Policies [Abstract]
Additional Cash Flow Information	Additional cash flow information was as follows: Six Months Ended 2023 2022 Cash paid for interest $ 270,358 $ 22,551 Cash paid for income taxes 66,500 45,500 Significant non-cash transactions: Unsettled securities transactions 10,988 110,623 Right-of-use lease assets obtained in exchange for lessee operating lease liabilities 8,914 8,857

Securities (Tables)

Securities (Tables)	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023 and December 31, 2022 is presented below. Amortized Gross Gross Estimated Allowance Net June 30, 2023 Residential mortgage-backed securities $ 1,265,818 $ — $ 72,286 $ 1,193,532 $ — $ 1,265,818 States and political subdivisions 2,424,169 24,288 99,491 2,348,966 (267) 2,423,902 Other 1,500 — 69 1,431 — 1,500 Total $ 3,691,487 $ 24,288 $ 171,846 $ 3,543,929 $ (267) $ 3,691,220 December 31, 2022 Residential mortgage-backed securities $ 526,122 $ — $ 65,322 $ 460,800 $ — $ 526,122 States and political subdivisions 2,111,619 13,048 119,033 2,005,634 (158) 2,111,461 Other 1,500 — 69 1,431 — 1,500 Total $ 2,639,241 $ 13,048 $ 184,424 $ 2,467,865 $ (158) $ 2,639,083
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 June 30, 2023 and December 31, 2022: States and Political Subdivisions Not Guaranteed or Pre-Refunded Guaranteed by the Texas PSF Guaranteed by Third Party Pre-Refunded Total Other June 30, 2023 Aaa/AAA $ 301,922 $ 1,544,702 $ 13,656 $ 52,860 $ 1,913,140 $ — Aa/AA 504,928 — 6,101 — 511,029 — Not rated — — — — — 1,500 Total $ 806,850 $ 1,544,702 $ 19,757 $ 52,860 $ 2,424,169 $ 1,500 December 31, 2022 Aaa/AAA $ 273,201 $ 1,422,442 $ — $ 121,961 $ 1,817,604 $ — Aa/AA 294,015 — — — 294,015 — Not rated — — — — — 1,500 Total $ 567,216 $ 1,422,442 $ — $ 121,961 $ 2,111,619 $ 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 six months ended June 30, 2023 and 2022. Three Months Ended Six Months Ended 2023 2022 2023 2022 Beginning balance $ 262 $ 158 $ 158 $ 158 Credit loss expense (benefit) 5 — 109 — Ending balance $ 267 $ 158 $ 267 $ 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 June 30, 2023 and December 31, 2022 is presented below. Amortized Gross Gross Allowance Estimated June 30, 2023 U.S. Treasury $ 5,456,656 $ — $ 383,768 $ — $ 5,072,888 Residential mortgage-backed securities 7,725,403 5,105 937,733 — 6,792,775 States and political subdivisions 5,636,095 1,098 296,177 — 5,341,016 Other 42,578 — — — 42,578 Total $ 18,860,732 $ 6,203 $ 1,617,678 $ — $ 17,249,257 December 31, 2022 U.S. Treasury $ 5,450,546 $ — $ 398,959 $ — $ 5,051,587 Residential mortgage-backed securities 7,316,824 8,050 948,638 — 6,376,236 States and political subdivisions 7,098,635 9,108 334,388 — 6,773,355 Other 42,427 — — — 42,427 Total $ 19,908,432 $ 17,158 $ 1,681,985 $ — $ 18,243,605
Securities, with Unrealized Losses Segregated by Length of Impairment	The table below summarizes, as of June 30, 2023, 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 $ 1,487,790 $ 58,237 $ 3,585,097 $ 325,531 $ 5,072,887 $ 383,768 Residential mortgage-backed securities 2,176,299 65,646 4,239,828 872,087 6,416,127 937,733 States and political subdivisions 3,391,385 45,640 1,543,520 250,537 4,934,905 296,177 Total $ 7,055,474 $ 169,523 $ 9,368,445 $ 1,448,155 $ 16,423,919 $ 1,617,678
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 June 30, 2023. 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 $ — $ — $ 513,530 $ 752,288 $ 1,265,818 States and political subdivisions 59,282 14,024 37,558 2,313,305 2,424,169 Other — 1,500 — — 1,500 Total $ 59,282 $ 15,524 $ 551,088 $ 3,065,593 $ 3,691,487 Estimated Fair Value Residential mortgage-backed securities $ — $ — $ 450,850 $ 742,682 $ 1,193,532 States and political subdivisions 59,242 13,949 36,609 2,239,166 2,348,966 Other — 1,431 — — 1,431 Total $ 59,242 $ 15,380 $ 487,459 $ 2,981,848 $ 3,543,929 Available For Sale Amortized Cost U. S. Treasury $ 1,286,197 $ 2,542,538 $ 1,435,692 $ 192,229 $ 5,456,656 Residential mortgage-backed securities 310 4,985 15,986 7,704,122 7,725,403 States and political subdivisions 439,111 317,371 831,502 4,048,111 5,636,095 Other — — — — 42,578 Total $ 1,725,618 $ 2,864,894 $ 2,283,180 $ 11,944,462 $ 18,860,732 Estimated Fair Value U. S. Treasury $ 1,257,329 $ 2,420,131 $ 1,250,420 $ 145,008 $ 5,072,888 Residential mortgage-backed securities 305 4,865 15,898 6,771,707 6,792,775 States and political subdivisions 438,969 315,373 811,631 3,775,043 5,341,016 Other — — — — 42,578 Total $ 1,696,603 $ 2,740,369 $ 2,077,949 $ 10,691,758 $ 17,249,257
Schedule of Realized Gain (Loss)	Sales of available for sale securities were as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Proceeds from sales $ 659,082 $ — $ 1,543,355 $ — Gross realized gains 561 — 5,417 — Gross realized losses (528) — (5,363) — Tax (expense) benefit of securities gains/losses (7) — (11) —
Investment Income	Premium amortization and discount accretion included in interest income on securities was as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Premium amortization $ (21,242) $ (28,053) $ (47,167) $ (57,113) Discount accretion 4,843 2,482 10,248 3,888 Net (premium amortization) discount accretion $ (16,399) $ (25,571) $ (36,919) $ (53,225)
Trading Account Securities, at Estimated Fair Value	Trading account securities, at estimated fair value, were as follows: June 30, December 31, U.S. Treasury $ 27,546 $ 25,879 States and political subdivisions 4,971 2,166 Total $ 32,517 $ 28,045
Net Gains and Losses on Trading Account Securities	Net gains and losses on trading account securities were as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Net gain on sales transactions $ 903 $ 1,012 $ 1,871 $ 1,352 Net mark-to-market gains (losses) (10) (76) (27) (244) Net gain (loss) on trading account securities $ 893 $ 936 $ 1,844 $ 1,108

Loans (Tables)

Loans (Tables)	6 Months Ended
	Jun. 30, 2023
Receivables [Abstract]
Loans	Loans were as follows: June 30, December 31, Commercial and industrial $ 5,726,804 $ 5,674,798 Energy: Production 718,829 696,570 Service 138,816 133,542 Other 128,926 95,617 Total energy 986,571 925,729 Paycheck Protection Program 22,333 34,852 Commercial real estate: Commercial mortgages 6,389,649 6,168,910 Construction 1,468,071 1,477,247 Land 535,247 537,168 Total commercial real estate 8,392,967 8,183,325 Consumer real estate: Home equity lines of credit 730,557 691,841 Home equity loans 575,284 449,507 Home improvement loans 680,811 577,377 Other 171,264 124,814 Total consumer real estate 2,157,916 1,843,539 Total real estate 10,550,883 10,026,864 Consumer and other 459,720 492,726 Total loans $ 17,746,311 $ 17,154,969
Non-Accrual Loans, Segregated by Class of Loans	Non-accrual loans, segregated by class of loans, were as follows: June 30, 2023 December 31, 2022 Total Non-Accrual Non-Accrual with No Credit Loss Allowance Total Non-Accrual Non-Accrual with No Credit Loss Allowance Commercial and industrial $ 22,217 $ 3,817 $ 18,130 $ 8,514 Energy 16,712 11,880 15,224 7,139 Commercial real estate: Buildings, land and other 25,682 6,617 3,552 1,991 Construction — — — — Consumer real estate 3,170 3,170 927 927 Consumer and other — — — — Total $ 67,781 $ 25,484 $ 37,833 $ 18,571
Financing Receivable, Non-Accrual Loans, Segregated by Class of Loan and Year of Origination	The following table presents non-accrual loans as of June 30, 2023 by class and year of origination. 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial and industrial $ — $ — $ 221 $ 754 $ 2,957 $ 1,172 $ 16,746 $ 367 $ 22,217 Energy 10,324 — — 59 1,349 2 4,832 146 16,712 Commercial real estate: Buildings, land and other 1,924 8 296 18,328 1,483 3,643 — — 25,682 Construction — — — — — — — — — Consumer real estate — — — 39 2,470 95 — 566 3,170 Consumer and other — — — — — — — — — Total $ 12,248 $ 8 $ 517 $ 19,180 $ 8,259 $ 4,912 $ 21,578 $ 1,079 $ 67,781
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 June 30, 2023 was as follows: Loans Loans Total Current Total Accruing Commercial and industrial $ 29,280 $ 5,224 $ 34,504 $ 5,692,300 $ 5,726,804 $ 3,025 Energy 2,224 6,386 8,610 977,961 986,571 — Paycheck Protection Program 80 2,725 2,805 19,528 22,333 2,725 Commercial real estate: Buildings, land and other 28,554 20,022 48,576 6,876,320 6,924,896 568 Construction 669 118 787 1,467,284 1,468,071 118 Consumer real estate 8,843 8,114 16,957 2,140,959 2,157,916 5,039 Consumer and other 5,153 336 5,489 454,231 459,720 336 Total $ 74,803 $ 42,925 $ 117,728 $ 17,628,583 $ 17,746,311 $ 11,811
Troubled debt restructurings	The period-end balance of loan modifications, segregated by type of modification, to borrowers experiencing financial difficulty during the six months ended June 30, 2023 and June 30, 2022 are set forth in the table below, regardless of whether such modifications resulted in a new loan. There were no commitments to lend additional funds to these borrowers at June 30, 2023. Payment Percent of Combination: Payment Delay and Term Extension Percent of June 30, 2023 Commercial and industrial $ — — % $ 16,020 0.3 % Commercial real estate: Buildings, land and other — — 20,466 0.3 $ — — $ 36,486 0.2 June 30, 2022 Commercial real estate: Buildings, land and other $ 1,116 — — — $ 1,116 — $ — —
Financing Receivables, Modified Loans Past Due in Excess of 90 Days or on Non-Accrual Status, Charge-offs and Proceeds From Sales at Period-End	Information as of or for the six months ended June 30, 2023 and June 30, 2022 related to loans modified (by type of modification) in the preceding twelve months, respectively, whereby the borrower was experiencing financial difficulty at the time of modification is set forth in the following table. June 30, 2023 June 30, 2022 Term Payment Combination: Payment Delay and Term Extension Term Payment Combination: Payment Delay and Term Extension Past due in excess of 90 days or on non-accrual status at period-end: Commercial and industrial $ — $ — $ 16,020 $ — $ — $ — Commercial real estate: Buildings, land and other — — 20,466 — 1,116 — $ — $ — $ 36,486 $ — $ 1,116 $ — Charge-offs during the period: Commercial real estate: Buildings, land and other $ — $ — $ — $ — $ 371 $ 352 Proceeds from sales: Commercial real estate: Buildings, land and other $ — $ — $ — $ — $ — $ 1,070
Weighted Average Risk Grades for All Commercial Loans by Class and Year of Origination	The following table presents weighted-average risk grades for all commercial loans, by class and year of origination/renewal, as of June 30, 2023. Paycheck Protection Program (“PPP”) loans are excluded as such loans are fully guaranteed by the Small Business Administration (“SBA”). 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total W/A Risk Grade Commercial and industrial Risk grades 1-8 $ 1,113,216 $ 919,731 $ 524,735 $ 406,763 $ 186,103 $ 243,703 $ 2,026,310 $ 48,004 $ 5,468,565 6.29 Risk grade 9 17,610 17,339 32,116 3,745 2,307 10,869 40,715 5,203 129,904 9.00 Risk grade 10 9,988 510 622 396 4,165 744 19,268 564 36,257 10.00 Risk grade 11 4,491 4,164 4,001 8,747 16,121 1,523 19,749 11,065 69,861 11.00 Risk grade 12 — — 221 702 2,687 1,172 14,607 367 19,756 12.00 Risk grade 13 — — — 52 270 — 2,139 — 2,461 13.00 $ 1,145,305 $ 941,744 $ 561,695 $ 420,405 $ 211,653 $ 258,011 $ 2,122,788 $ 65,203 $ 5,726,804 6.46 W/A risk grade 6.31 6.76 7.10 5.93 6.57 6.17 6.31 7.66 6.46 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total W/A Risk Grade Energy Risk grades 1-8 $ 301,108 $ 65,831 $ 83,174 $ 4,240 $ 2,393 $ 5,297 $ 457,225 $ 33,858 $ 953,126 5.79 Risk grade 9 311 4,456 139 — 445 589 3,603 1,972 11,515 9.00 Risk grade 10 — — — — 355 189 — — 544 10.00 Risk grade 11 — — 106 170 3,101 12 1,285 — 4,674 11.00 Risk grade 12 10,324 — — 59 1,349 2 2,132 146 14,012 12.00 Risk grade 13 — — — — — — 2,700 — 2,700 13.00 $ 311,743 $ 70,287 $ 83,419 $ 4,469 $ 7,643 $ 6,089 $ 466,945 $ 35,976 $ 986,571 5.96 W/A risk grade 6.32 6.60 5.78 7.68 9.83 7.14 5.58 5.69 5.96 Commercial real estate: Buildings, land, other Risk grades 1-8 $ 699,039 $ 1,735,438 $ 1,421,130 $ 851,503 $ 570,561 $ 1,009,089 $ 150,060 $ 103,188 $ 6,540,008 6.97 Risk grade 9 9,069 15,323 10,729 40,843 70,271 27,324 1,980 1,214 176,753 9.00 Risk grade 10 491 29,583 7,991 4,086 1,754 3,796 — 2,646 50,347 10.00 Risk grade 11 7,653 6,163 48,496 8,477 — 57,948 2,993 376 132,106 11.00 Risk grade 12 1,924 8 296 17,178 1,483 3,493 — — 24,382 12.00 Risk grade 13 — — — 1,150 — 150 — — 1,300 13.00 $ 718,176 $ 1,786,515 $ 1,488,642 $ 923,237 $ 644,069 $ 1,101,800 $ 155,033 $ 107,424 $ 6,924,896 7.14 W/A risk grade 7.10 7.05 7.28 7.22 7.02 7.17 7.13 6.50 7.14 Construction Risk grades 1-8 $ 271,025 $ 523,461 $ 342,339 $ 49,547 $ 945 $ 1,666 $ 179,127 $ — $ 1,368,110 7.19 Risk grade 9 9,975 14,668 3,067 2,100 — — 3,291 — 33,101 9.00 Risk grade 10 18,297 — 7,347 — — — 9,126 — 34,770 10.00 Risk grade 11 — 31,972 118 — — — — — 32,090 11.00 Risk grade 12 — — — — — — — — — 12.00 Risk grade 13 — — — — — — — — — 13.00 $ 299,297 $ 570,101 $ 352,871 $ 51,647 $ 945 $ 1,666 $ 191,544 $ — $ 1,468,071 7.38 W/A risk grade 7.68 7.39 7.39 4.63 7.07 6.77 7.65 — 7.38 Total commercial real estate $ 1,017,473 $ 2,356,616 $ 1,841,513 $ 974,884 $ 645,014 $ 1,103,466 $ 346,577 $ 107,424 $ 8,392,967 7.18 W/A risk grade 7.27 7.13 7.30 7.09 7.02 7.17 7.41 6.50 7.18
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, 2022. Refer to our 2022 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 6.24 $ 5,435,917 5.44 $ 887,182 6.94 $ 6,340,028 7.04 $ 1,430,012 6.96 $ 7,770,040 Risk grade 9 9.00 146,192 9.00 11,112 9.00 189,928 9.00 34,952 9.00 224,880 Risk grade 10 10.00 37,596 10.00 642 10.00 91,020 10.00 931 10.00 91,951 Risk grade 11 11.00 36,963 11.00 11,569 11.00 81,550 11.00 11,352 11.00 92,902 Risk grade 12 12.00 12,521 12.00 10,840 12.00 2,957 12.00 — 12.00 2,957 Risk grade 13 13.00 5,609 13.00 4,384 13.00 595 13.00 — 13.00 595 Total 6.39 $ 5,674,798 5.67 $ 925,729 7.09 $ 6,706,078 7.12 $ 1,477,247 7.10 $ 8,183,325
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 June 30, 2023 was as follows: 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total Consumer real estate: Past due 30-89 days $ 297 $ 1,126 $ 1,075 $ 236 $ 480 $ 1,534 $ 3,861 $ 234 $ 8,843 Past due 90 or more days — 95 172 63 2,539 1,081 523 3,641 8,114 Total past due 297 1,221 1,247 299 3,019 2,615 4,384 3,875 16,957 Current loans 284,398 438,609 300,363 182,845 62,030 150,136 713,920 8,658 2,140,959 Total $ 284,695 $ 439,830 $ 301,610 $ 183,144 $ 65,049 $ 152,751 $ 718,304 $ 12,533 $ 2,157,916 Consumer and other: Past due 30-89 days $ 2,202 $ 316 $ 158 $ 12 $ 42 $ 49 $ 2,226 $ 148 $ 5,153 Past due 90 or more days 84 34 1 — — — 212 5 336 Total past due 2,286 350 159 12 42 49 2,438 153 5,489 Current loans 49,542 39,133 13,771 4,820 1,985 1,900 320,720 22,360 454,231 Total $ 51,828 $ 39,483 $ 13,930 $ 4,832 $ 2,027 $ 1,949 $ 323,158 $ 22,513 $ 459,720
Revolving Loans Converted to Term [Table Text Block]	Revolving loans that converted to term during the three and six months ended June 30, 2023 and 2022 were as follows: Three Months Ended June 30, Six Months Ended June 30, 2023 2022 2023 2022 Commercial and industrial $ 3,835 $ 16,518 $ 14,606 $ 21,973 Energy — 247 2,567 247 Commercial real estate: Buildings, land and other 5,944 10,681 5,944 10,726 Construction — 13 — 4,248 Consumer real estate 1,064 888 1,743 1,684 Consumer and other 1,669 1,792 3,671 5,868 Total $ 12,512 $ 30,139 $ 28,531 $ 44,746
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 June 30, 2023 and December 31, 2022. No allowance for credit losses has been recognized for PPP loans as such loans are fully guaranteed by the SBA. June 30, 2023 Commercial Energy Commercial Consumer Consumer Total Modeled expected credit losses $ 46,435 $ 5,733 $ 15,496 $ 12,594 $ 5,511 $ 85,769 Q-Factor and other qualitative adjustments 26,270 6,496 104,130 441 4,052 141,389 Specific allocations 2,461 2,700 1,300 — — 6,461 Total $ 75,166 $ 14,929 $ 120,926 $ 13,035 $ 9,563 $ 233,619 December 31, 2022 Modeled expected credit losses $ 61,918 $ 8,531 $ 27,013 $ 7,847 $ 4,983 $ 110,292 Q-Factor and other qualitative adjustments 36,237 5,148 61,572 157 2,034 105,148 Specific allocations 6,082 4,383 1,716 — — 12,181 Total $ 104,237 $ 18,062 $ 90,301 $ 8,004 $ 7,017 $ 227,621
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 six months ended June 30, 2023 and 2022. 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: June 30, 2023 Beginning balance $ 78,465 $ 19,191 $ 115,693 $ 9,708 $ 8,457 $ 231,514 Credit loss expense (benefit) 2,404 (4,433) 5,133 3,822 5,007 11,933 Charge-offs (7,136) (518) — (1,080) (7,016) (15,750) Recoveries 1,433 689 100 585 3,115 5,922 Net (charge-offs) recoveries (5,703) 171 100 (495) (3,901) (9,828) Ending balance $ 75,166 $ 14,929 $ 120,926 $ 13,035 $ 9,563 $ 233,619 June 30, 2022 Beginning balance $ 87,026 $ 15,422 $ 128,954 $ 6,359 $ 9,074 $ 246,835 Credit loss expense (benefit) 942 427 (12,232) 583 5,884 (4,396) Charge-offs (1,891) — — (131) (5,322) (7,344) Recoveries 1,193 418 384 43 2,499 4,537 Net (charge-offs) recoveries (698) 418 384 (88) (2,823) (2,807) Ending balance $ 87,270 $ 16,267 $ 117,106 $ 6,854 $ 12,135 $ 239,632 Commercial Energy Commercial Consumer Consumer Total Six months ended: June 30, 2023 Beginning balance $ 104,237 $ 18,062 $ 90,301 $ 8,004 $ 7,017 $ 227,621 Credit loss expense (benefit) (18,280) (3,467) 30,494 5,105 10,756 24,608 Charge-offs (13,316) (518) — (1,330) (13,958) (29,122) Recoveries 2,525 852 131 1,256 5,748 10,512 Net (charge-offs) recoveries (10,791) 334 131 (74) (8,210) (18,610) Ending balance $ 75,166 $ 14,929 $ 120,926 $ 13,035 $ 9,563 $ 233,619 June 30, 2022 Beginning balance $ 72,091 $ 17,217 $ 144,936 $ 6,585 $ 7,837 $ 248,666 Credit loss expense (benefit) 18,503 (1,617) (27,841) 557 10,466 68 Charge-offs (5,346) (371) (702) (362) (11,093) (17,874) Recoveries 2,022 1,038 713 74 4,925 8,772 Net (charge-offs) recoveries (3,324) 667 11 (288) (6,168) (9,102) Ending balance $ 87,270 $ 16,267 $ 117,106 $ 6,854 $ 12,135 $ 239,632
Financing Receivable, Gross Charge-Offs By Year of Origination	The following table presents year-to-date gross charge-offs by year of origination as of June 30, 2023. 2023 2022 2021 2020 2019 Prior Revolving Loans Revolving Loans Converted to Term Total Commercial and industrial $ 124 $ 208 $ 178 $ 55 $ 25 $ 29 $ 7,427 $ 5,270 $ 13,316 Energy — — — — — — — 518 518 Commercial real estate: Buildings, land and other — — — — — — — — — Construction — — — — — — — — — Consumer real estate — — 280 — — 89 961 — 1,330 Consumer and other 8,143 4,354 57 12 — 23 1,051 318 13,958 Total $ 8,267 $ 4,562 $ 515 $ 67 $ 25 $ 141 $ 9,439 $ 6,106 $ 29,122
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 June 30, 2023 and December 31, 2022. June 30, 2023 December 31, 2022 Loan Specific Allocations Loan Specific Allocations Commercial and industrial $ 20,862 $ 2,461 $ 18,980 $ 6,082 Energy 16,445 2,700 15,058 4,383 Paycheck Protection Program — — — — Commercial real estate: Buildings, land and other 24,954 1,300 17,711 1,716 Construction — — — — Consumer real estate 3,030 — 827 — Consumer and other — — — — Total $ 65,291 $ 6,461 $ 52,576 $ 12,181

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Goodwill	Goodwill and other intangible assets are presented in the table below. June 30, December 31, Goodwill $ 654,952 $ 654,952 Other intangible assets: Core deposits $ 155 $ 310 Customer relationships 53 76 $ 208 $ 386
Estimated Aggregate Future Amortization Expense for Intangible Assets	The estimated aggregate future amortization expense for intangible assets remaining as of June 30, 2023 is as follows: Remainder of 2023 $ 105 2024 87 2025 11 2026 5 $ 208

Deposits (Tables)

Deposits (Tables)	6 Months Ended
	Jun. 30, 2023
Disclosure Text Block [Abstract]
Deposit Liabilities, Type	Deposits were as follows: June 30, December 31, Non-interest-bearing demand deposits $ 14,904,614 $ 17,598,234 Interest-bearing deposits: Savings and interest checking 10,540,458 12,333,675 Money market accounts 11,026,368 12,227,247 Time accounts 4,229,390 1,795,040 Total interest-bearing deposits 25,796,216 26,355,962 Total deposits $ 40,700,830 $ 43,954,196
Additional Information About Corporation's Deposits	The table below presents additional information about our deposits. Public funds in excess of deposit insurance limits are included in the totals for deposits not covered by insurance; however, such deposits are generally fully collateralized by securities. June 30, December 31, Deposits from foreign sources (primarily Mexico) $ 1,036,777 $ 1,048,943 Non-interest-bearing public funds deposits 447,194 788,040 Interest-bearing public funds deposits 696,521 758,761 Total deposits not covered by deposit insurance 20,630,167 23,839,797 Time deposits not covered by deposit insurance 1,670,388 430,128

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Financial Instruments with Off-Balance-Sheet Risk	Financial instruments with off-balance-sheet risk were as follows: June 30, December 31, Commitments to extend credit $ 12,208,032 $ 12,137,957 Standby letters of credit 405,900 383,851 Deferred standby letter of credit fees 2,176 2,236
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 Six Months Ended 2023 2022 2023 2022 Beginning balance $ 54,918 $ 45,850 $ 58,593 $ 50,314 Credit loss expense (benefit) (2,037) 4,396 (5,712) (68) Ending balance $ 52,881 $ 50,246 $ 52,881 $ 50,246
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 Six Months Ended 2023 2022 2023 2022 Amortization of lease right-of-use assets $ 8,747 $ 8,209 $ 17,512 $ 16,314 Short-term lease expense 493 490 902 1,103 Non-lease components (including taxes, insurance, common maintenance, etc.) 3,662 2,748 7,043 5,768 Total $ 12,902 $ 11,447 $ 25,457 $ 23,185

Capital and Regulatory Matters

Capital and Regulatory Matters (Tables)	6 Months Ended
	Jun. 30, 2023
Banking Regulation, Common Equity Tier 1 Risk-Based Capital [Abstract]
Actual and Required Capital Ratios	The following table presents actual and required capital ratios as of June 30, 2023 and December 31, 2022 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 2022 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 June 30, 2023 Common Equity Tier 1 to Risk-Weighted Assets Cullen/Frost $ 3,943,110 13.42 % $ 2,056,052 7.00 % N/A N/A Frost Bank 3,973,809 13.55 2,053,467 7.00 $ 1,906,791 6.50 % Tier 1 Capital to Risk-Weighted Assets Cullen/Frost 4,088,562 13.92 2,496,634 8.50 1,762,330 6.00 Frost Bank 3,973,809 13.55 2,493,496 8.50 2,346,820 8.00 Total Capital to Risk-Weighted Assets Cullen/Frost 4,520,634 15.39 3,084,077 10.50 2,937,217 10.00 Frost Bank 4,225,881 14.41 3,080,201 10.50 2,933,525 10.00 Leverage Ratio Cullen/Frost 4,088,562 8.11 2,016,414 4.00 N/A N/A Frost Bank 3,973,809 7.88 2,015,896 4.00 2,519,870 5.00 December 31, 2022 Common Equity Tier 1 to Risk-Weighted Assets Cullen/Frost $ 3,751,200 12.85 % $ 2,042,876 7.00 % N/A N/A Frost Bank 3,789,056 13.00 2,040,388 7.00 $ 1,894,646 6.50 % Tier 1 Capital to Risk-Weighted Assets Cullen/Frost 3,896,652 13.35 2,480,635 8.50 1,751,036 6.00 Frost Bank 3,789,056 13.00 2,477,614 8.50 2,331,872 8.00 Total Capital to Risk-Weighted Assets Cullen/Frost 4,330,982 14.84 3,064,313 10.50 2,918,394 10.00 Frost Bank 4,023,386 13.80 3,060,583 10.50 2,914,841 10.00 Leverage Ratio Cullen/Frost 3,896,652 7.29 2,136,680 4.00 N/A N/A Frost Bank 3,789,056 7.09 2,136,316 4.00 2,670,395 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.

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023 and December 31, 2022. June 30, 2023 December 31, 2022 Notional Estimated Notional Estimated Derivatives designated as hedges of fair value: Financial institution counterparties: Loan/lease interest rate swaps – assets $ — $ — $ 1,614 $ 19 Non-hedging interest rate derivatives: Financial institution counterparties: Loan/lease interest rate swaps – assets 1,162,694 78,404 1,165,812 70,416 Loan/lease interest rate swaps – liabilities 72,833 (1,332) 78,798 (1,102) Loan/lease interest rate caps – assets 229,804 14,557 246,442 15,256 Customer counterparties: Loan/lease interest rate swaps – assets 78,789 1,401 53,570 1,102 Loan/lease interest rate swaps – liabilities 1,156,738 (78,402) 1,175,563 (79,175) Loan/lease interest rate caps – liabilities 229,804 (14,557) 246,442 (15,256)
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 June 30, 2023 were as follows: Weighted-Average Interest Interest Interest rate swaps: Non-hedging interest rate swaps – financial institution counterparties 3.96 % 5.62 % Non-hedging interest rate swaps – customer counterparties 5.62 3.96
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. June 30, 2023 December 31, 2022 Notional Notional Estimated Notional Estimated Financial institution counterparties: Oil – assets Barrels 4,134 $ 30,701 4,024 $ 27,082 Oil – liabilities Barrels 5,345 (21,229) 6,068 (53,579) Natural gas – assets MMBTUs 16,694 6,668 16,539 6,220 Natural gas – liabilities MMBTUs 9,871 (6,841) 15,682 (19,138) Customer counterparties: Oil – assets Barrels 5,391 21,580 6,068 54,219 Oil – liabilities Barrels 4,088 (30,255) 4,024 (26,551) Natural gas – assets MMBTUs 9,871 6,865 15,682 19,164 Natural gas – liabilities MMBTUs 16,694 (6,477) 16,539 (6,124)
Schedule of Foreign Exchange Contracts, Statement of Financial Position	The notional amounts and fair values of open foreign currency forward and option contracts are presented in the following table. June 30, 2023 December 31, 2022 Notional Notional Estimated Notional Estimated Financial institution counterparties: Forward and option contracts – assets EUR — $ — 875 $ 1 Forward and option contracts – liabilities EUR — — 875 (10) Customer counterparties: Forward and option contracts – assets EUR — — 875 10 Forward and option contracts – liabilities EUR — — 875 (1)
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 Six Months Ended 2023 2022 2023 2022 Commercial loan/lease interest rate swaps: Amount of gain (loss) included in interest income on loans $ 4 $ (5) $ 16 $ (18) Amount of (gain) loss included in other non-interest expense 4 3 4 5
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 Six Months Ended 2023 2022 2023 2022 Non-hedging interest rate derivatives: Other non-interest income $ 1,002 $ 515 $ 1,712 $ 1,031 Other non-interest expense 1 — — — Non-hedging commodity derivatives: Other non-interest income 503 649 925 1,578 Non-hedging foreign currency derivatives: Other non-interest income — 45 25 63

Balance Sheet Offsetting (Table

Balance Sheet Offsetting (Tables)	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments Eligible for Offset Consolidated Balance Sheet	Information about financial instruments that are eligible for offset in the consolidated balance sheet as of June 30, 2023 is presented in the following tables. Gross Amount Gross Amount Net Amount June 30, 2023 Financial assets: Derivatives: Interest rate contracts $ 92,961 $ — $ 92,961 Commodity contracts 37,369 — 37,369 Total derivatives 130,330 — 130,330 Resell agreements 84,650 — 84,650 Total $ 214,980 $ — $ 214,980 Financial liabilities: Derivatives: Interest rate contracts $ 1,332 $ — $ 1,332 Commodity contracts 28,070 — 28,070 Total derivatives 29,402 — 29,402 Repurchase agreements 3,569,870 — 3,569,870 Total $ 3,599,272 $ — $ 3,599,272	Information about financial instruments that are eligible for offset in the consolidated balance sheet as of December 31, 2022 is presented in the following tables. Gross Amount Gross Amount Net Amount December 31, 2022 Financial assets: Derivatives: Interest rate contracts $ 85,691 $ — $ 85,691 Commodity contracts 33,302 — 33,302 Foreign currency contracts 1 — 1 Total derivatives 118,994 — 118,994 Resell agreements 87,150 — 87,150 Total $ 206,144 $ — $ 206,144 Financial liabilities: Derivatives: Interest rate contracts $ 1,102 $ — $ 1,102 Commodity contracts 72,717 — 72,717 Foreign currency contracts 10 — 10 Total derivatives 73,829 — 73,829 Repurchase agreements 4,660,641 — 4,660,641 Total $ 4,734,470 $ — $ 4,734,470
Financial Instruments Derivative Assets Liabilities and Resell Agreements Net of Amount Not Offset	Gross Amounts Not Offset Net Amount Financial Collateral Net June 30, 2023 Financial assets: Derivatives: Counterparty B $ 32,143 $ (9,548) $ (22,595) $ — Counterparty E 16,312 (896) (15,240) 176 Counterparty F 18,387 (8,839) (9,463) 85 Counterparty G 10,484 — (10,430) 54 Other counterparties 53,004 (10,119) (42,861) 24 Total derivatives 130,330 (29,402) (100,589) 339 Resell agreements 84,650 — (84,650) — Total $ 214,980 $ (29,402) $ (185,239) $ 339 Financial liabilities: Derivatives: Counterparty B $ 9,548 $ (9,548) $ — $ — Counterparty E 896 (896) — — Counterparty F 8,839 (8,839) — — Other counterparties 10,119 (10,119) — — Total derivatives 29,402 (29,402) — — Repurchase agreements 3,569,870 — (3,569,870) — Total $ 3,599,272 $ (29,402) $ (3,569,870) $ —	Gross Amounts Not Offset Net Amount Financial Collateral Net December 31, 2022 Financial assets: Derivatives: Counterparty B $ 39,370 $ (24,500) $ (14,870) $ — Counterparty E 14,430 (47) (14,131) 252 Counterparty F 17,297 (17,297) — — Counterparty G 10,660 — (10,660) — Other counterparties 37,237 (20,684) (16,307) 246 Total derivatives 118,994 (62,528) (55,968) 498 Resell agreements 87,150 — (87,150) — Total $ 206,144 $ (62,528) $ (143,118) $ 498 Financial liabilities: Derivatives: Counterparty B $ 24,500 $ (24,500) $ — $ — Counterparty E 47 (47) — — Counterparty F 27,747 (17,297) (8,479) 1,971 Counterparty G — — — — Other counterparties 21,535 (20,684) (851) — Total derivatives 73,829 (62,528) (9,330) 1,971 Repurchase agreements 4,660,641 — (4,660,641) — Total $ 4,734,470 $ (62,528) $ (4,669,971) $ 1,971
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 June 30, 2023 and December 31, 2022 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 June 30, 2023 Repurchase agreements: U.S. Treasury $ 2,716,439 $ — $ — $ — $ 2,716,439 Residential mortgage-backed securities 853,431 — — — 853,431 Total borrowings $ 3,569,870 $ — $ — $ — $ 3,569,870 Gross amount of recognized liabilities for repurchase agreements $ 3,569,870 Amounts related to agreements not included in offsetting disclosures above $ — December 31, 2022 Repurchase agreements: U.S. Treasury $ 3,735,061 $ — $ — $ — $ 3,735,061 Residential mortgage-backed securities 925,580 — — — 925,580 Total borrowings $ 4,660,641 $ — $ — $ — $ 4,660,641 Gross amount of recognized liabilities for repurchase agreements $ 4,660,641 Amounts related to agreements not included in offsetting disclosures above $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023, there were 514,028 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, 2023 45,661 $ 87.15 465,319 $ 105.36 213,749 $ 96.20 616,227 $ 71.27 Granted 8,503 103.47 2,594 128.42 — — — — Exercised/vested — — (1,957) 91.96 (28,151) 85.74 (33,905) 72.13 Forfeited/expired — — (1,415) 116.02 (18,254) 85.74 — — Balance, June 30, 2023 54,164 89.71 464,541 105.52 167,344 99.10 582,322 71.22
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 Six Months Ended 2023 2022 2023 2022 New shares issued from available authorized shares — — 49,887 — Shares issued from available treasury stock 13,626 28,832 14,126 144,262 Proceeds from stock option exercises $ 946 $ 751 $ 2,446 $ 6,490
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 Six Months Ended 2023 2022 2023 2022 Non-vested stock units $ 2,864 $ 2,291 $ 6,171 $ 4,649 Deferred stock units 880 720 880 720 Performance stock units 1,049 407 2,484 161 Total $ 4,793 $ 3,418 $ 9,535 $ 5,530 Income tax benefit $ 800 $ 612 $ 1,868 $ 1,320
Unrecognized Stock-Based Compensation Expense	Unrecognized stock-based compensation expense at June 30, 2023 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 $ 15,768 Performance stock units 7,029 Total $ 22,797

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	6 Months Ended
	Jun. 30, 2023
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 Six Months Ended 2023 2022 2023 2022 Net income $ 162,118 $ 119,114 $ 339,771 $ 218,216 Less: Preferred stock dividends 1,669 1,669 3,338 3,338 Net income available to common shareholders 160,449 117,445 336,433 214,878 Less: Earnings allocated to participating securities 1,645 1,036 3,468 1,888 Net earnings allocated to common stock $ 158,804 $ 116,409 $ 332,965 $ 212,990 Distributed earnings allocated to common stock $ 55,783 $ 48,092 $ 111,789 $ 96,143 Undistributed earnings allocated to common stock 103,021 68,317 221,176 116,847 Net earnings allocated to common stock $ 158,804 $ 116,409 $ 332,965 $ 212,990 Weighted-average shares outstanding for basic earnings per common share 64,240,789 64,112,828 64,306,809 64,082,185 Dilutive effect of stock compensation 187,172 354,401 225,267 382,395 Weighted-average shares outstanding for diluted earnings per common share 64,427,961 64,467,229 64,532,076 64,464,580

Defined Benefit Plans (Tables)

Defined Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2023
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 Six Months Ended 2023 2022 2023 2022 Expected return on plan assets, net of expenses $ (2,740) $ (3,492) $ (5,480) $ (6,983) Interest cost on projected benefit obligation 1,746 1,004 3,492 2,008 Net amortization and deferral 870 741 1,740 1,482 Net periodic expense (benefit) $ (124) $ (1,747) $ (248) $ (3,493)

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2023
Income Tax Disclosure [Abstract]
Income Tax Expense	Income tax expense was as follows: Three Months Ended Six Months Ended 2023 2022 2023 2022 Current income tax expense $ 32,413 $ 22,646 $ 67,408 $ 35,705 Deferred income tax expense (benefit) (680) (1,972) (2,489) (2,404) Income tax expense, as reported $ 31,733 $ 20,674 $ 64,919 $ 33,301 Effective tax rate 16.4 % 14.8 % 16.0 % 13.2 %

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2023
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 $ (206,863) $ (43,441) $ (163,422) $ (636,523) $ (133,670) $ (502,853) Change in net unrealized gain on securities transferred to held to maturity (162) (34) (128) (189) (40) (149) Reclassification adjustment for net (gains) losses included in net income (33) (7) (26) — — — Total securities available for sale and transferred securities (207,058) (43,482) (163,576) (636,712) (133,710) (503,002) 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) 870 183 687 741 155 586 Total defined-benefit post-retirement benefit plans 870 183 687 741 155 586 Total other comprehensive income (loss) $ (206,188) $ (43,299) $ (162,889) $ (635,971) $ (133,555) $ (502,416) Six Months Ended Six 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 $ 53,406 $ 11,215 $ 42,191 $ (1,547,318) $ (324,937) $ (1,222,381) Change in net unrealized gain on securities transferred to held to maturity (322) (67) (255) (398) (84) (314) Reclassification adjustment for net (gains) losses included in net income (54) (11) (43) — — — Total securities available for sale and transferred securities 53,030 11,137 41,893 (1,547,716) (325,021) (1,222,695) 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) 1,740 366 1,374 1,482 311 1,171 Total defined-benefit post-retirement benefit plans 1,740 366 1,374 1,482 311 1,171 Total other comprehensive income (loss) $ 54,770 $ 11,503 $ 43,267 $ (1,546,234) $ (324,710) $ (1,221,524)
Schedule of Accumulated Other Comprehensive Income (Loss)	Activity in accumulated other comprehensive income (loss), net of tax, was as follows: Securities Defined Accumulated Balance at January 1, 2023 $ (1,313,791) $ (34,503) $ (1,348,294) Other comprehensive income (loss) before reclassifications 41,936 — 41,936 Reclassification of amounts included in net income (43) 1,374 1,331 Net other comprehensive income (loss) during period 41,893 1,374 43,267 Balance at June 30, 2023 $ (1,271,898) $ (33,129) $ (1,305,027) Balance at January 1, 2022 $ 380,209 $ (32,891) $ 347,318 Other comprehensive income (loss) before reclassifications (1,222,695) — (1,222,695) Reclassification of amounts included in net income — 1,171 1,171 Net other comprehensive income (loss) during period (1,222,695) 1,171 (1,221,524) Balance at June 30, 2022 $ (842,486) $ (31,720) $ (874,206)

Operating Segments (Tables)

Operating Segments (Tables)	6 Months Ended
	Jun. 30, 2023
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: June 30, 2023 Net interest income (expense) $ 385,720 $ 2,090 $ (2,544) $ 385,266 Credit loss expense 9,901 — — 9,901 Non-interest income 57,808 46,147 (427) 103,528 Non-interest expense 246,927 35,558 2,557 285,042 Income (loss) before income taxes 186,700 12,679 (5,528) 193,851 Income tax expense (benefit) 30,636 2,663 (1,566) 31,733 Net income (loss) 156,064 10,016 (3,962) 162,118 Preferred stock dividends — — 1,669 1,669 Net income (loss) available to common shareholders $ 156,064 $ 10,016 $ (5,631) $ 160,449 Revenues from (expenses to) external customers $ 443,528 $ 48,237 $ (2,971) $ 488,794 June 30, 2022 Net interest income (expense) $ 289,186 $ 958 $ (1,936) $ 288,208 Credit loss expense (benefit) 1 (1) — — Non-interest income 55,397 43,054 (524) 97,927 Non-interest expense 211,044 33,158 2,145 246,347 Income (loss) before income taxes 133,538 10,855 (4,605) 139,788 Income tax expense (benefit) 19,821 2,279 (1,426) 20,674 Net income (loss) 113,717 8,576 (3,179) 119,114 Preferred stock dividends — — 1,669 1,669 Net income (loss) available to common shareholders $ 113,717 $ 8,576 $ (4,848) $ 117,445 Revenues from (expenses to) external customers $ 344,583 $ 44,012 $ (2,460) $ 386,135 Banking Frost Wealth Non-Banks Consolidated Six months ended: June 30, 2023 Net interest income (expense) $ 785,857 $ 3,744 $ (4,515) $ 785,086 Credit loss expense (benefit) 19,003 2 — 19,005 Non-interest income 121,451 88,185 (843) 208,793 Non-interest expense 496,794 69,505 3,885 570,184 Income (loss) before income taxes 391,511 22,422 (9,243) 404,690 Income tax expense (benefit) 62,754 4,709 (2,544) 64,919 Net income (loss) 328,757 17,713 (6,699) 339,771 Preferred stock dividends — — 3,338 3,338 Net income (loss) available to common shareholders $ 328,757 $ 17,713 $ (10,037) $ 336,433 Revenues from (expenses to) external customers $ 907,308 $ 91,929 $ (5,358) $ 993,879 June 30, 2022 Net interest income (expense) $ 539,305 $ 1,658 $ (3,684) $ 537,279 Credit loss expense — — — — Non-interest income 114,103 86,283 (1,069) 199,317 Non-interest expense 417,582 64,068 3,429 485,079 Income (loss) before income taxes 235,826 23,873 (8,182) 251,517 Income tax expense (benefit) 30,835 5,013 (2,547) 33,301 Net income (loss) 204,991 18,860 (5,635) 218,216 Preferred stock dividends — — 3,338 3,338 Net income (loss) available to common shareholders $ 204,991 $ 18,860 $ (8,973) $ 214,878 Revenues from (expenses to) external customers $ 653,408 $ 87,941 $ (4,753) $ 736,596

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2023
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 June 30, 2023 and December 31, 2022, 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 June 30, 2023 Securities available for sale: U.S. Treasury $ 5,072,888 $ — $ — $ 5,072,888 Residential mortgage-backed securities — 6,792,775 — 6,792,775 States and political subdivisions — 5,341,016 — 5,341,016 Other — 42,578 — 42,578 Trading account securities: U.S. Treasury 27,546 — — 27,546 States and political subdivisions — 4,971 — 4,971 Derivative assets: Interest rate swaps, caps and floors — 94,362 — 94,362 Commodity swaps and options — 65,814 — 65,814 Derivative liabilities: Interest rate swaps, caps and floors — 94,291 — 94,291 Commodity swaps and options — 64,802 — 64,802 December 31, 2022 Securities available for sale: U.S. Treasury $ 5,051,587 $ — $ — $ 5,051,587 Residential mortgage-backed securities — 6,376,236 — 6,376,236 States and political subdivisions — 6,773,355 — 6,773,355 Other — 42,427 — 42,427 Trading account securities: U.S. Treasury 25,879 — — 25,879 States and political subdivisions — 2,166 — 2,166 Derivative assets: Interest rate swaps, caps and floors — 86,793 — 86,793 Commodity swaps and options — 106,685 — 106,685 Foreign currency forward contracts 11 — — 11 Derivative liabilities: Interest rate swaps, caps and floors — 95,533 — 95,533 Commodity swaps and options — 105,392 — 105,392 Foreign currency forward contracts 11 — — 11
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. Six Months Ended Six Months Ended Level 2 Level 3 Level 2 Level 3 Carrying value before allocations $ 19,064 $ 20,171 $ 5,454 $ 3,614 Specific (allocations) reversals of prior allocations (1,300) (2,100) (1,327) 6,877 Fair value $ 17,764 $ 18,071 $ 4,127 $ 10,491
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: June 30, 2023 December 31, 2022 Carrying Estimated Carrying Estimated Financial assets: Level 2 inputs: Cash and cash equivalents $ 7,107,336 $ 7,107,336 $ 12,028,132 $ 12,028,132 Securities held to maturity 3,691,220 3,543,929 2,639,083 2,467,865 Cash surrender value of life insurance policies 190,575 190,575 190,188 190,188 Accrued interest receivable 236,967 236,967 243,682 243,682 Level 3 inputs: Loans, net 17,512,692 16,933,702 16,927,348 16,343,417 Financial liabilities: Level 2 inputs: Deposits 40,700,830 40,683,556 43,954,196 43,920,741 Federal funds purchased 13,525 13,525 51,650 51,650 Repurchase agreements 3,569,870 3,569,870 4,660,641 4,660,641 Junior subordinated deferrable interest debentures 123,098 123,712 123,069 123,712 Subordinated notes 99,413 94,571 99,335 97,014 Accrued interest payable 40,523 40,523 18,444 18,444

Significant Accounting Polici_4

Significant Accounting Policies - Additional Cash Flow Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Accounting Policies [Abstract]
Cash paid for interest	$ 270,358	$ 22,551
Cash paid for income taxes	66,500	45,500
Unsettled securities transactions	10,988	110,623
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities	$ 8,914	$ 8,857

Securities - Additional Informa

Securities - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule Of Marketable Securities [Line Items]
AOCI, Debt Securities, Available-for-sale, Adjustment, Pre Tax	$ 1,500	$ 1,800
Net unamortized unrealized gain on transferred securities included in accumulated other comprehensive income, net of tax	$ 1,200	1,400
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	74.30%
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0	0
Held-to-maturity Securities [Member]
Schedule Of Marketable Securities [Line Items]
Carry Value of Securities Pledged	943,900	256,300
Accrued interest receivable	39,400	30,200
Available-for-sale Securities [Member]
Schedule Of Marketable Securities [Line Items]
Carry Value of Securities Pledged	5,200,000	8,000,000
Accrued interest receivable	$ 121,800	$ 140,600

Securities Securities - Amortiz

Securities Securities - Amortized Cost, Allowance for Credit Losses and Estimated Fair Value of Securities Held to Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	$ 3,691,487	$ 2,639,241
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	24,288	13,048
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	171,846	184,424
Debt Securities, Held-to-maturity, Fair Value	3,543,929	2,467,865
Securities, held-to-maturity, allowance for credit loss	(267)	(158)
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	3,691,220	2,639,083
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	1,265,818	526,122
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	72,286	65,322
Debt Securities, Held-to-maturity, Fair Value	1,193,532	460,800
Securities, held-to-maturity, allowance for credit loss	0	0
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	1,265,818	526,122
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Amortized Cost	2,424,169	2,111,619
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	24,288	13,048
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	99,491	119,033
Debt Securities, Held-to-maturity, Fair Value	2,348,966	2,005,634
Securities, held-to-maturity, allowance for credit loss	(267)	(158)
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	2,423,902	2,111,461
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	69	69
Debt Securities, Held-to-maturity, Fair Value	1,431	1,431
Securities, held-to-maturity, allowance for credit loss	0	0
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	$ 1,500	$ 1,500

Securities Securities - Moody's

Securities Securities - Moody's and/or Standard & Poor's Bond Rating (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 3,691,487	$ 2,639,241
US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	2,424,169	2,111,619
Other Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,500	1,500
Moody's, Aaa Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,913,140	1,817,604
Moody's, Aaa Rating | Other Investments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	0	0
Moody's, Aa1 Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	511,029	294,015
Moody's, Aa1 Rating | 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	806,850	567,216
Not Guaranteed or Pre-Refunded [Member] | Moody's, Aaa Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	301,922	273,201
Not Guaranteed or Pre-Refunded [Member] | Moody's, Aa1 Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	504,928	294,015
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	1,544,702	1,422,442
Guaranteed by the Texas PSF [Member] | Moody's, Aaa Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,544,702	1,422,442
Guaranteed by the Texas PSF [Member] | Moody's, Aa1 Rating | 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
Guaranteed by Third Party | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	19,757	0
Guaranteed by Third Party | Moody's, Aaa Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	13,656	0
Guaranteed by Third Party | Moody's, Aa1 Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	6,101	0
Guaranteed by Third Party | 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	52,860	121,961
Pre-Refunded [Member] | Moody's, Aaa Rating | US States and Political Subdivisions Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	52,860	121,961
Pre-Refunded [Member] | Moody's, Aa1 Rating | 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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Securities, held-to-maturity, allowance for credit loss	$ 267		$ 267			$ 158
Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities, held-to-maturity, allowance for credit loss	267	$ 158	267	$ 158	$ 262	$ 158	$ 158	$ 158
Credit loss expense (benefit)	$ 5	$ 0	$ 109	$ 0

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	Jun. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 18,860,732	$ 19,908,432
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	6,203	17,158
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,617,678	1,681,985
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	17,249,257	18,243,605
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,456,656	5,450,546
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	383,768	398,959
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	5,072,888	5,051,587
Residential Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	7,725,403	7,316,824
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	5,105	8,050
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	937,733	948,638
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	6,792,775	6,376,236
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	5,636,095	7,098,635
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,098	9,108
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	296,177	334,388
Debt Securities, Available-for-sale, Allowance for Credit Loss	0	0
Securities available for sale, at estimated fair value	5,341,016	6,773,355
Other Investments [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	42,578	42,427
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	$ 42,578	$ 42,427

Securities - Securities Availab

Securities - Securities Available for Sale, with Unrealized Losses Segregated by Length of Impairment (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Available-for-Sale Securities [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 7,055,474
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	169,523
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	9,368,445
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,448,155
Debt Securities, Available-for-sale, Unrealized Loss Position	16,423,919
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,617,678	$ 1,681,985
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	1,487,790
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	58,237
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	3,585,097
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	325,531
Debt Securities, Available-for-sale, Unrealized Loss Position	5,072,887
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	383,768	398,959
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	2,176,299
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	65,646
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,239,828
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	872,087
Debt Securities, Available-for-sale, Unrealized Loss Position	6,416,127
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	937,733	948,638
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	3,391,385
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	45,640
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,543,520
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	250,537
Debt Securities, Available-for-sale, Unrealized Loss Position	4,934,905
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 296,177	$ 334,388

Securities - Amortized Cost and

Securities - Amortized Cost and Estimated Fair Value of Securities, Excluding Trading Securities, Presented by Contractual Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	$ 59,282
Held to Maturity, Due after one year through five years, Amortized Cost	15,524
Held to Maturity, Due after five years through ten years, Amortized Cost	551,088
Held to Maturity, Due after ten years, Amortized Cost	3,065,593
Held to Maturity, Amortized Cost	3,691,487	$ 2,639,241
Held to Maturity, Due in one year or less, Estimated Fair Value	59,242
Held to Maturity, Due after one year through five years, Estimated Fair Value	15,380
Held to Maturity, Due after five years through ten years, Estimated Fair Value	487,459
Held to Maturity, Due after ten years, Estimated Fair Value	2,981,848
Held to Maturity, Estimated Fair Value	3,543,929	2,467,865
Available-for-sale Securities, Due in one year or less, Amortized Cost	1,725,618
Available for Sale, Due after one year through five years, Amortized Cost	2,864,894
Available for Sale, Due after five years through ten years, Amortized Cost	2,283,180
Available for Sale, Due after ten years, Amortized Cost	11,944,462
Debt Securities, Available-for-sale, Amortized Cost	18,860,732	19,908,432
Available for Sale, Due in one year or less, Estimated Fair Value	1,696,603
Available for Sale, Due after one year through five years, Estimated Fair Value	2,740,369
Available for Sale, Due after five years through ten years, Estimated Fair Value	2,077,949
Available for Sale, Due after ten years, Estimated Fair Value	10,691,758
Securities available for sale, at estimated fair value	17,249,257	18,243,605
US Treasury Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale Securities, Due in one year or less, Amortized Cost	1,286,197
Available for Sale, Due after one year through five years, Amortized Cost	2,542,538
Available for Sale, Due after five years through ten years, Amortized Cost	1,435,692
Available for Sale, Due after ten years, Amortized Cost	192,229
Debt Securities, Available-for-sale, Amortized Cost	5,456,656	5,450,546
Available for Sale, Due in one year or less, Estimated Fair Value	1,257,329
Available for Sale, Due after one year through five years, Estimated Fair Value	2,420,131
Available for Sale, Due after five years through ten years, Estimated Fair Value	1,250,420
Available for Sale, Due after ten years, Estimated Fair Value	145,008
Securities available for sale, at estimated fair value	5,072,888	5,051,587
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	513,530
Held to Maturity, Due after ten years, Amortized Cost	752,288
Held to Maturity, Amortized Cost	1,265,818	526,122
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	450,850
Held to Maturity, Due after ten years, Estimated Fair Value	742,682
Held to Maturity, Estimated Fair Value	1,193,532	460,800
Available-for-sale Securities, Due in one year or less, Amortized Cost	310
Available for Sale, Due after one year through five years, Amortized Cost	4,985
Available for Sale, Due after five years through ten years, Amortized Cost	15,986
Available for Sale, Due after ten years, Amortized Cost	7,704,122
Debt Securities, Available-for-sale, Amortized Cost	7,725,403	7,316,824
Available for Sale, Due in one year or less, Estimated Fair Value	305
Available for Sale, Due after one year through five years, Estimated Fair Value	4,865
Available for Sale, Due after five years through ten years, Estimated Fair Value	15,898
Available for Sale, Due after ten years, Estimated Fair Value	6,771,707
Securities available for sale, at estimated fair value	6,792,775	6,376,236
US States and Political Subdivisions Debt Securities [Member]
Schedule of Investments [Line Items]
Held to Maturity, Due in one year or less, Amortized Cost	59,282
Held to Maturity, Due after one year through five years, Amortized Cost	14,024
Held to Maturity, Due after five years through ten years, Amortized Cost	37,558
Held to Maturity, Due after ten years, Amortized Cost	2,313,305
Held to Maturity, Amortized Cost	2,424,169	2,111,619
Held to Maturity, Due in one year or less, Estimated Fair Value	59,242
Held to Maturity, Due after one year through five years, Estimated Fair Value	13,949
Held to Maturity, Due after five years through ten years, Estimated Fair Value	36,609
Held to Maturity, Due after ten years, Estimated Fair Value	2,239,166
Held to Maturity, Estimated Fair Value	2,348,966	2,005,634
Available-for-sale Securities, Due in one year or less, Amortized Cost	439,111
Available for Sale, Due after one year through five years, Amortized Cost	317,371
Available for Sale, Due after five years through ten years, Amortized Cost	831,502
Available for Sale, Due after ten years, Amortized Cost	4,048,111
Debt Securities, Available-for-sale, Amortized Cost	5,636,095	7,098,635
Available for Sale, Due in one year or less, Estimated Fair Value	438,969
Available for Sale, Due after one year through five years, Estimated Fair Value	315,373
Available for Sale, Due after five years through ten years, Estimated Fair Value	811,631
Available for Sale, Due after ten years, Estimated Fair Value	3,775,043
Securities available for sale, at estimated fair value	5,341,016	6,773,355
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	1,431
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	1,431	1,431
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	42,578	42,427
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	$ 42,578	$ 42,427

Securities - Sales of Available

Securities - Sales of Available for Sale Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales	$ 659,082	$ 0	$ 1,543,355	$ 0
Gross realized gains	561	0	5,417	0
Gross realized losses	(528)	0	(5,363)	0
Tax (expense) benefit of securities gains/losses	$ (7)	$ 0	$ (11)	$ 0

Securities Securities - Premium

Securities Securities - Premium Amortization and Discount Accretion Included in Income on Securities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Premium amortization	$ (21,242)	$ (28,053)	$ (47,167)	$ (57,113)
Discount accretion	4,843	2,482	10,248	3,888
Net (premium amortization) discount accretion	$ (16,399)	$ (25,571)	$ (36,919)	$ (53,225)

Securities - Trading Account Se

Securities - Trading Account Securities, at Estimated Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	$ 32,517	$ 28,045
U.S. Treasury [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	27,546	25,879
States and political subdivisions [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading account securities	$ 4,971	$ 2,166

Securities - Net Gains and Loss

Securities - Net Gains and Losses on Trading Account Securities (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Net gain on sales transactions	$ 903	$ 1,012	$ 1,871	$ 1,352
Net mark-to-market gains (losses)	(10)	(76)	(27)	(244)
Net gain (loss) on trading account securities	$ 893	$ 936	$ 1,844	$ 1,108

Loans - Additional Information

Loans - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
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	$ 389,200		$ 389,200			$ 391,300
Texas Leading Index economic condition indicator	127.7		127.7			130.3
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			$ (45,000)
Financing Receivable, Allowance for Credit Loss	$ 233,619		233,619			$ 227,621
Loans, net of unearned discounts	17,746,311		17,746,311			17,154,969
Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	12,248		12,248
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8		8
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	8,267		8,267
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,562		4,562
Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	0	$ 1,116	0	$ 1,116
Additional Funding Agreement Terms
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 0		$ 0
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of total energy loans to total loans	5.60%		5.60%
Financing Receivable, Allowance for Credit Loss	$ 14,929	16,267	$ 14,929	16,267	$ 19,191	18,062	$ 15,422	$ 17,217
Financing Receivable, Allowance for Credit Loss, Writeoff	518	0	518	371
Loans, net of unearned discounts	986,571		986,571			925,729
Financing Receivable, Year One, Originated, Current Fiscal Year	311,743		311,743
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	70,287		70,287
Commercial and Industrial Total Energy Loans [Member] | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	10,324		10,324
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Commercial and Industrial Total Energy Loans [Member] | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	0	0	0	0		0
Loans, net of unearned discounts	22,333		22,333			34,852
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	835	436	1,400	843
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	13,035	6,854	13,035	6,854	9,708	8,004	6,359	6,585
Financing Receivable, Allowance for Credit Loss, Writeoff	1,080	131	1,330	362
Loans, net of unearned discounts	2,157,916		2,157,916			1,843,539
Total consumer real estate loans [Member] | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Total consumer real estate loans [Member] | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	75,166	87,270	75,166	87,270	78,465	104,237	87,026	72,091
Financing Receivable, Allowance for Credit Loss, Writeoff	7,136	1,891	13,316	5,346
Loans, net of unearned discounts	5,726,804		5,726,804			5,674,798
Financing Receivable, Year One, Originated, Current Fiscal Year	1,145,305		1,145,305
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	941,744		941,744
Commercial Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Commercial Portfolio Segment [Member] | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	124		124
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	208		208
Commercial Portfolio Segment [Member] | Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	0		0
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Loss	9,563	12,135	9,563	12,135	$ 8,457	7,017	$ 9,074	$ 7,837
Financing Receivable, Allowance for Credit Loss, Writeoff	7,016	$ 5,322	13,958	$ 11,093
Loans, net of unearned discounts	459,720		459,720			492,726
Consumer Loan [Member] | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Consumer Loan [Member] | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	8,143		8,143
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,354		4,354
Bank Overdrafts | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	8,100		8,100
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,200		4,200
Commitments to Extend Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial instruments with off- balance-sheet risk	12,208,032		12,208,032			12,137,957
Commitments to Extend Credit [Member] | Automobile Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	454,900		454,900
Commitments to Extend Credit [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	1,000,000		1,000,000
Standby Letters of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financial instruments with off- balance-sheet risk	405,900		405,900			383,851
Standby Letters of Credit [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	84,100		84,100
Standby Letters of Credit [Member] | Automobiles
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded balances	20,100		20,100
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest Receivable	$ 73,900		$ 73,900			$ 68,700

Loans - Loans (Detail)

Loans - Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 17,746,311	$ 17,154,969
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	5,726,804	5,674,798
Energy Production [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	718,829	696,570
Energy Service [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	138,816	133,542
Energy Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	128,926	95,617
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	986,571	925,729
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	22,333	34,852
Commercial mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	6,389,649	6,168,910
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	1,468,071	1,477,247
Commercial land loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	535,247	537,168
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	8,392,967	8,183,325
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	730,557	691,841
Home Equity Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	575,284	449,507
Home Improvement Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	680,811	577,377
Other consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	171,264	124,814
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	2,157,916	1,843,539
Real Estate Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	10,550,883	10,026,864
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned discounts	$ 459,720	$ 492,726

Loans - Non-Accrual Loans, Segr

Loans - Non-Accrual Loans, Segregated by Class of Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	$ 67,781	$ 37,833
Non-accrual with no credit loss allowance	25,484	18,571
Commercial Portfolio Segment [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	22,217	18,130
Non-accrual with no credit loss allowance	3,817	8,514
Commercial and Industrial Total Energy Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	16,712	15,224
Non-accrual with no credit loss allowance	11,880	7,139
Commercial Real Estate Buildings Land And Other Loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	25,682	3,552
Non-accrual with no credit loss allowance	6,617	1,991
Construction Loans [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
Total consumer real estate loans [Member]
Non Accrual Loans Segregated By Class Of Loans [Line Items]
Non-accrual loans	3,170	927
Non-accrual with no credit loss allowance	3,170	927
Consumer Loan [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

Loans Loans - Non-Accrual Loans

Loans Loans - Non-Accrual Loans, Segregated by Class of Loans and Year of Origination (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	$ 67,781	$ 37,833
Nonperforming Financial Instruments [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	12,248
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	517
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	19,180
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	8,259
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,912
Financing Receivable, Revolving	21,578
Financing Receivable, Revolving, Converted to Term Loan	1,079
Commercial Portfolio Segment [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,145,305
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	941,744
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	561,695
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	420,405
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	211,653
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	258,011
Financing Receivable, Revolving	2,122,788
Non-accrual loans	22,217	18,130
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	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	221
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	754
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,957
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,172
Financing Receivable, Revolving	16,746
Financing Receivable, Revolving, Converted to Term Loan	367
Commercial and Industrial Total Energy Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	311,743
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	70,287
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	83,419
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,469
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7,643
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,089
Financing Receivable, Revolving	466,945
Non-accrual loans	16,712	15,224
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	10,324
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	59
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,349
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2
Financing Receivable, Revolving	4,832
Financing Receivable, Revolving, Converted to Term Loan	146
Commercial Real Estate Buildings Land And Other Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	718,176
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,786,515
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,488,642
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	923,237
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	644,069
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,101,800
Financing Receivable, Revolving	155,033
Non-accrual loans	25,682	3,552
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	1,924
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	296
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	18,328
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,483
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,643
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	299,297
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	570,101
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	352,871
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	51,647
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	945
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,666
Financing Receivable, Revolving	191,544
Non-accrual loans	0	0
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	3,170	927
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	39
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,470
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	95
Financing Receivable, Revolving	0
Financing Receivable, Revolving, Converted to Term Loan	566
Consumer Loan [Member]
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans	0	$ 0
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	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Total loans	$ 17,746,311	$ 17,154,969
Accruing Loans 90 or More Days Past Due	11,811
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total loans	5,726,804	5,674,798
Accruing Loans 90 or More Days Past Due	3,025
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	986,571	925,729
Accruing Loans 90 or More Days Past Due	0
Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Total loans	22,333	34,852
Accruing Loans 90 or More Days Past Due	2,725
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	6,924,896	6,706,078
Accruing Loans 90 or More Days Past Due	568
Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	1,468,071	1,477,247
Accruing Loans 90 or More Days Past Due	118
Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Total loans	2,157,916	1,843,539
Accruing Loans 90 or More Days Past Due	5,039
Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Total loans	459,720	$ 492,726
Accruing Loans 90 or More Days Past Due	336
Financing Receivables, 30 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	74,803
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	29,280
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	2,224
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	80
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	28,554
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	669
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	8,843
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	5,153
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	42,925
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	5,224
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,386
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	2,725
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	20,022
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	118
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	8,114
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	336
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	117,728
Financial Asset, Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	34,504
Financial Asset, Past Due | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	8,610
Financial Asset, Past Due | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,805
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	48,576
Financial Asset, Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	787
Financial Asset, Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	16,957
Financial Asset, Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,489
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	17,628,583
Financial Asset, Not Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,692,300
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	977,961
Financial Asset, Not Past Due | Paycheck Protection Program [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	19,528
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	6,876,320
Financial Asset, Not Past Due | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,467,284
Financial Asset, Not Past Due | Total consumer real estate loans [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,140,959
Financial Asset, Not Past Due | Consumer Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 454,231

Loans - Loan Modification (Deta

Loans - Loan Modification (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 17,746,311		$ 17,154,969
Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 1,116
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0%	0%
Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 36,486	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.20%	0%
Commercial Portfolio Segment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 5,726,804		5,674,798
Commercial Portfolio Segment [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0%
Commercial Portfolio Segment [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 16,020
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.30%
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 6,924,896		$ 6,706,078
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0	$ 1,116
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0%	0%
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 20,466	$ 0
Financing Receivable, Modified in Period, to Total Financing Receivables, Percentage	0.30%	0%

Loans - Financing Receivables,

Loans - Financing Receivables, Modified Loans Past Due in Excess of 90 Days or on Non-Accrual Status at Period-End (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 17,746,311	$ 17,154,969
Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		$ 1,116
Payment Deferral | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,116
Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	36,486		0
Combination: Payment Delay and Term Extention | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	36,486		0
Extended Maturity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	6,924,896	6,706,078
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,116
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,116
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral | Charge-offs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		371
Commercial Real Estate Buildings Land And Other Loans [Member] | Payment Deferral | Proceeds from sales
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	20,466		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	20,466		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention | Charge-offs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		352
Commercial Real Estate Buildings Land And Other Loans [Member] | Combination: Payment Delay and Term Extention | Proceeds from sales
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		1,070
Commercial Real Estate Buildings Land And Other Loans [Member] | Extended Maturity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Extended Maturity | Charge-offs
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Real Estate Buildings Land And Other Loans [Member] | Extended Maturity | Proceeds from sales
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	986,571	925,729
Commercial Portfolio Segment [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	5,726,804	$ 5,674,798
Commercial Portfolio Segment [Member] | Payment Deferral
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0
Commercial Portfolio Segment [Member] | Payment Deferral | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	0		0
Commercial Portfolio Segment [Member] | Combination: Payment Delay and Term Extention
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	16,020
Commercial Portfolio Segment [Member] | Combination: Payment Delay and Term Extention | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	16,020		0
Commercial Portfolio Segment [Member] | Extended Maturity | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Loans, net of unearned discounts	$ 0		$ 0

Loans Loans - Weighted Average

Loans Loans - Weighted Average Risk Grade for All Commercial Loans by Class and Year of Origination (Details) $ in Thousands	Jun. 30, 2023 USD ($) Grade	Dec. 31, 2022 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 17,746,311	$ 17,154,969
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,145,305
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	941,744
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	561,695
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	420,405
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	211,653
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	258,011
Financing Receivable, Revolving	2,122,788
Loans and Leases Receivable, Net of Deferred Income	$ 5,726,804	$ 5,674,798
Weighted Average Risk Grade For Loans | Grade	6.46	6.39
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 311,743
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	70,287
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	83,419
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,469
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7,643
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,089
Financing Receivable, Revolving	466,945
Loans and Leases Receivable, Net of Deferred Income	$ 986,571	$ 925,729
Weighted Average Risk Grade For Loans | Grade	5.96	5.67
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	$ 718,176
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,786,515
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,488,642
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	923,237
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	644,069
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,101,800
Financing Receivable, Revolving	155,033
Loans and Leases Receivable, Net of Deferred Income	$ 6,924,896	$ 6,706,078
Weighted Average Risk Grade For Loans | Grade	7.14	7.09
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 299,297
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	570,101
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	352,871
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	51,647
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	945
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,666
Financing Receivable, Revolving	191,544
Loans and Leases Receivable, Net of Deferred Income	$ 1,468,071	$ 1,477,247
Weighted Average Risk Grade For Loans | Grade	7.38	7.12
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,017,473
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	2,356,616
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,841,513
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	974,884
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	645,014
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,103,466
Financing Receivable, Revolving	346,577
Loans and Leases Receivable, Net of Deferred Income	$ 8,392,967	$ 8,183,325
Weighted Average Risk Grade For Loans | Grade	7.18	7.10
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	$ 1,113,216
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	919,731
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	524,735
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	406,763
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	186,103
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	243,703
Financing Receivable, Revolving	2,026,310
Loans and Leases Receivable, Net of Deferred Income	$ 5,468,565	$ 5,435,917
Weighted Average Risk Grade For Loans | Grade	6.29	6.24
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	$ 301,108
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	65,831
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	83,174
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,240
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,393
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	5,297
Financing Receivable, Revolving	457,225
Loans and Leases Receivable, Net of Deferred Income	$ 953,126	$ 887,182
Weighted Average Risk Grade For Loans | Grade	5.79	5.44
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	$ 699,039
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,735,438
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,421,130
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	851,503
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	570,561
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,009,089
Financing Receivable, Revolving	150,060
Loans and Leases Receivable, Net of Deferred Income	$ 6,540,008	$ 6,340,028
Weighted Average Risk Grade For Loans | Grade	6.97	6.94
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	$ 271,025
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	523,461
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	342,339
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	49,547
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	945
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,666
Financing Receivable, Revolving	179,127
Loans and Leases Receivable, Net of Deferred Income	$ 1,368,110	$ 1,430,012
Weighted Average Risk Grade For Loans | Grade	7.19	7.04
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		$ 7,770,040
Weighted Average Risk Grade For Loans | Grade		6.96
Risk Grade Nine [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 17,610
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	17,339
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	32,116
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	3,745
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,307
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	10,869
Financing Receivable, Revolving	40,715
Loans and Leases Receivable, Net of Deferred Income	$ 129,904	$ 146,192
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	$ 311
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,456
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	139
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	445
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	589
Financing Receivable, Revolving	3,603
Loans and Leases Receivable, Net of Deferred Income	$ 11,515	$ 11,112
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	$ 9,069
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	15,323
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	10,729
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	40,843
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	70,271
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	27,324
Financing Receivable, Revolving	1,980
Loans and Leases Receivable, Net of Deferred Income	$ 176,753	$ 189,928
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	$ 9,975
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	14,668
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	3,067
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	2,100
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	3,291
Loans and Leases Receivable, Net of Deferred Income	$ 33,101	$ 34,952
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		$ 224,880
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	$ 9,988
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	510
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	622
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	396
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	4,165
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	744
Financing Receivable, Revolving	19,268
Loans and Leases Receivable, Net of Deferred Income	$ 36,257	$ 37,596
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	0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	355
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	189
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 544	$ 642
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	$ 491
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	29,583
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	7,991
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,086
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,754
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,796
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 50,347	$ 91,020
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	$ 18,297
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	7,347
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	9,126
Loans and Leases Receivable, Net of Deferred Income	$ 34,770	$ 931
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		$ 91,951
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	$ 4,491
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,164
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	4,001
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8,747
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	16,121
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,523
Financing Receivable, Revolving	19,749
Loans and Leases Receivable, Net of Deferred Income	$ 69,861	$ 36,963
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	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	106
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	170
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	3,101
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	12
Financing Receivable, Revolving	1,285
Loans and Leases Receivable, Net of Deferred Income	$ 4,674	$ 11,569
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	$ 7,653
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	6,163
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	48,496
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	8,477
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	57,948
Financing Receivable, Revolving	2,993
Loans and Leases Receivable, Net of Deferred Income	$ 132,106	$ 81,550
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	31,972
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	118
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	$ 32,090	$ 11,352
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		$ 92,902
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	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	221
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	702
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,687
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,172
Financing Receivable, Revolving	14,607
Loans and Leases Receivable, Net of Deferred Income	$ 19,756	$ 12,521
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	$ 10,324
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	59
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,349
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2
Financing Receivable, Revolving	2,132
Loans and Leases Receivable, Net of Deferred Income	$ 14,012	$ 10,840
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	$ 1,924
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	296
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	17,178
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,483
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,493
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 24,382	$ 2,957
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	$ 0
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		$ 2,957
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	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	52
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	270
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0
Financing Receivable, Revolving	2,139
Loans and Leases Receivable, Net of Deferred Income	$ 2,461	$ 5,609
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	$ 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	2,700
Loans and Leases Receivable, Net of Deferred Income	$ 2,700	$ 4,384
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	$ 0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	1,150
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	150
Financing Receivable, Revolving	0
Loans and Leases Receivable, Net of Deferred Income	$ 1,300	$ 595
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	$ 0
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		$ 595
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	6.31
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	5.58
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	7.13
Revolving Credit Facility [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.65
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	7.41
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	$ 65,203
Weighted Average Risk Grade For Loans | Grade	7.66
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	$ 35,976
Weighted Average Risk Grade For Loans | Grade	5.69
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	$ 107,424
Weighted Average Risk Grade For Loans | Grade	6.50
Revolving Loans Converted to Term [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 0
Weighted Average Risk Grade For Loans | Grade	0
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	$ 107,424
Weighted Average Risk Grade For Loans | Grade	6.50
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	$ 48,004
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	33,858
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	103,188
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	0
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	5,203
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	1,972
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	1,214
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	564
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	0
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	2,646
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	11,065
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	376
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	367
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	146
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	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	0
Revolving Loans Converted to Term [Member] | Risk Grade Thirteen [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Revolving, Converted to Term Loan	$ 0
2023 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.31
2023 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.32
2023 [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	7.10
2023 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.68
2023 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.27
2022 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.76
2022 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.60
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	7.05
2022 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.39
2022 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.13
2021 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.10
2021 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.78
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	7.28
2021 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.39
2021 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.30
2020 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	5.93
2020 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.68
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	7.22
2020 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	4.63
2020 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.09
2019 [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.57
2019 [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	9.83
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	7.02
2019 [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.07
2019 [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.02
Prior Years [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.17
Prior Years [Member] | Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.14
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	7.17
Prior Years [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	6.77
Prior Years [Member] | Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade For Loans | Grade	7.17

Loans - Weighted Average Risk G

Loans - Weighted Average Risk Grades for All Commercial Loans by Class (Detail) $ in Thousands	Jun. 30, 2023 USD ($) Grade	Dec. 31, 2022 USD ($) Grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 17,746,311	$ 17,154,969
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.46	6.39
Loans and Leases Receivable, Net of Deferred Income	$ 5,726,804	$ 5,674,798
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	5.96	5.67
Loans and Leases Receivable, Net of Deferred Income	$ 986,571	$ 925,729
Commercial Real Estate Buildings Land And Other Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.14	7.09
Loans and Leases Receivable, Net of Deferred Income	$ 6,924,896	$ 6,706,078
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.38	7.12
Loans and Leases Receivable, Net of Deferred Income	$ 1,468,071	$ 1,477,247
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.18	7.10
Loans and Leases Receivable, Net of Deferred Income	$ 8,392,967	$ 8,183,325
Risk Grade One To Eight [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	6.29	6.24
Loans and Leases Receivable, Net of Deferred Income	$ 5,468,565	$ 5,435,917
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	5.79	5.44
Loans and Leases Receivable, Net of Deferred Income	$ 953,126	$ 887,182
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	6.97	6.94
Loans and Leases Receivable, Net of Deferred Income	$ 6,540,008	$ 6,340,028
Risk Grade One To Eight [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted Average Risk Grade | Grade	7.19	7.04
Loans and Leases Receivable, Net of Deferred Income	$ 1,368,110	$ 1,430,012
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		6.96
Loans and Leases Receivable, Net of Deferred Income		$ 7,770,040
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	$ 129,904	$ 146,192
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	$ 11,515	$ 11,112
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	$ 176,753	$ 189,928
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	$ 33,101	$ 34,952
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		$ 224,880
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	$ 36,257	$ 37,596
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	$ 544	$ 642
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	$ 50,347	$ 91,020
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	$ 34,770	$ 931
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		$ 91,951
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	$ 69,861	$ 36,963
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	$ 4,674	$ 11,569
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	$ 132,106	$ 81,550
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	$ 32,090	$ 11,352
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		$ 92,902
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	$ 19,756	$ 12,521
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	$ 14,012	$ 10,840
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	$ 24,382	$ 2,957
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	$ 0
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		$ 2,957
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	$ 2,461	$ 5,609
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	$ 2,700	$ 4,384
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	$ 1,300	$ 595
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	$ 0
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		$ 595

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	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 17,746,311	$ 17,154,969
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,157,916	1,843,539
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	459,720	$ 492,726
Financing Receivables, 30 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	74,803
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	8,843
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	5,153
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	42,925
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	8,114
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	336
Financial Asset, Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	117,728
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	16,957
Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,489
Financial Asset, Not Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	17,628,583
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	2,140,959
Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	454,231
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	718,304
Revolving Credit Facility [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	323,158
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	3,861
Revolving Credit Facility [Member] | Financing Receivables, 30 to 89 Days Past Due [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,226
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	523
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	212
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	4,384
Revolving Credit Facility [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,438
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	713,920
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	320,720
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	12,533
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	22,513
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	234
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	148
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	3,641
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	5
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	3,875
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	153
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	8,658
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	22,360
2023 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	284,695
2023 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	51,828
2023 [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	297
2023 [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	2,202
2023 [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
2023 [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	84
2023 [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	297
2023 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,286
2023 [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	284,398
2023 [Member] | Financial Asset, Not Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	49,542
2022 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	439,830
2022 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	39,483
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	1,126
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	316
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	95
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	34
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	1,221
2022 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	350
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	438,609
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	39,133
2021 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	301,610
2021 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	13,930
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	1,075
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	158
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	172
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	1
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	1,247
2021 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	159
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	300,363
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	13,771
2020 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	183,144
2020 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	4,832
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	236
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	12
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	63
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	299
2020 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	12
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	182,845
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	4,820
2019 [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	65,049
2019 [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,027
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	480
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	42
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	2,539
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	0
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	3,019
2019 [Member] | Financial Asset, Past Due | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, before Allowance for Credit Loss	42
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	62,030
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	1,985
Prior Years [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	152,751
Prior Years [Member] | Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,949
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	1,534
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	49
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	1,081
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	2,615
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	49
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	150,136
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	$ 1,900

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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	$ 12,512	$ 30,139	$ 28,531	$ 44,746
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	3,835	16,518	14,606	21,973
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	0	247	2,567	247
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	5,944	10,681	5,944	10,726
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	0	13	0	4,248
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	1,064	888	1,743	1,684
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining Revolving Loans Converted to Term During Period	$ 1,669	$ 1,792	$ 3,671	$ 5,868

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	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	$ 233,619		$ 227,621
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	75,166	$ 78,465	104,237	$ 87,270	$ 87,026	$ 72,091
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	14,929	19,191	18,062	16,267	15,422	17,217
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	120,926	115,693	90,301	117,106	128,954	144,936
Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	13,035	9,708	8,004	6,854	6,359	6,585
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	9,563	8,457	7,017	12,135	9,074	7,837
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	233,619	$ 231,514	227,621	$ 239,632	$ 246,835	$ 248,666
Modeled Expected Credit Losses [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	85,769		110,292
Modeled Expected Credit Losses [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	46,435		61,918
Modeled Expected Credit Losses [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,733		8,531
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	15,496		27,013
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	12,594		7,847
Modeled Expected Credit Losses [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	5,511		4,983
Q-factor adjustments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	141,389		105,148
Q-factor adjustments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	26,270		36,237
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	6,496		5,148
Q-factor adjustments [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	104,130		61,572
Q-factor adjustments [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	441		157
Q-factor adjustments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	4,052		2,034
Specific Valuation Allowances [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	6,461		12,181
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	2,461		6,082
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	2,700		4,383
Specific Valuation Allowances [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	1,300		1,716
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss	0		0
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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance			$ 227,621
Ending balance	$ 233,619		233,619
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	78,465	$ 87,026	104,237	$ 72,091
Credit loss, expense (reversal)	2,404	942	(18,280)	18,503
Charge-offs	(7,136)	(1,891)	(13,316)	(5,346)
Recoveries	1,433	1,193	2,525	2,022
Net charge-offs	(5,703)	(698)	(10,791)	(3,324)
Ending balance	75,166	87,270	75,166	87,270
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	19,191	15,422	18,062	17,217
Credit loss, expense (reversal)	(4,433)	427	(3,467)	(1,617)
Charge-offs	(518)	0	(518)	(371)
Recoveries	689	418	852	1,038
Net charge-offs	171	418	334	667
Ending balance	14,929	16,267	14,929	16,267
Commercial Real Estate Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	115,693	128,954	90,301	144,936
Credit loss, expense (reversal)	5,133	(12,232)	30,494	(27,841)
Charge-offs	0	0	0	(702)
Recoveries	100	384	131	713
Net charge-offs	100	384	131	11
Ending balance	120,926	117,106	120,926	117,106
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	9,708	6,359	8,004	6,585
Credit loss, expense (reversal)	3,822	583	5,105	557
Charge-offs	(1,080)	(131)	(1,330)	(362)
Recoveries	585	43	1,256	74
Net charge-offs	(495)	(88)	(74)	(288)
Ending balance	13,035	6,854	13,035	6,854
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	8,457	9,074	7,017	7,837
Credit loss, expense (reversal)	5,007	5,884	10,756	10,466
Charge-offs	(7,016)	(5,322)	(13,958)	(11,093)
Recoveries	3,115	2,499	5,748	4,925
Net charge-offs	(3,901)	(2,823)	(8,210)	(6,168)
Ending balance	9,563	12,135	9,563	12,135
Loans Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	231,514	246,835	227,621	248,666
Credit loss, expense (reversal)	11,933	(4,396)	24,608	68
Charge-offs	(15,750)	(7,344)	(29,122)	(17,874)
Recoveries	5,922	4,537	10,512	8,772
Net charge-offs	(9,828)	(2,807)	(18,610)	(9,102)
Ending balance	$ 233,619	$ 239,632	$ 233,619	$ 239,632

Loans - Financing Receivable, G

Loans - Financing Receivable, Gross Charge-Offs By Year of Origination (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 1,145,305		$ 1,145,305
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	941,744		941,744
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	561,695		561,695
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	420,405		420,405
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	211,653		211,653
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	258,011		258,011
Financing Receivable, Revolving	2,122,788		2,122,788
Financing Receivable, Allowance for Credit Loss, Writeoff	7,136	$ 1,891	13,316	$ 5,346
Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	311,743		311,743
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	70,287		70,287
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	83,419		83,419
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	4,469		4,469
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	7,643		7,643
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	6,089		6,089
Financing Receivable, Revolving	466,945		466,945
Financing Receivable, Allowance for Credit Loss, Writeoff	518	0	518	371
Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	718,176		718,176
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	1,786,515		1,786,515
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	1,488,642		1,488,642
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	923,237		923,237
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	644,069		644,069
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,101,800		1,101,800
Financing Receivable, Revolving	155,033		155,033
Financing Receivable, Allowance for Credit Loss, Writeoff			0
Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	299,297		299,297
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	570,101		570,101
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	352,871		352,871
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	51,647		51,647
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	945		945
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,666		1,666
Financing Receivable, Revolving	191,544		191,544
Financing Receivable, Allowance for Credit Loss, Writeoff			0
Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	1,080	131	1,330	362
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	7,016	5,322	13,958	11,093
Loans Receivable [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Allowance for Credit Loss, Writeoff	15,750	$ 7,344	29,122	$ 17,874
Nonperforming Financial Instruments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	12,248		12,248
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8		8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	517		517
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	19,180		19,180
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	8,259		8,259
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	4,912		4,912
Financing Receivable, Revolving	21,578		21,578
Financing Receivable, Revolving, Converted to Term Loan	1,079		1,079
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	221		221
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	754		754
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,957		2,957
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	1,172		1,172
Financing Receivable, Revolving	16,746		16,746
Financing Receivable, Revolving, Converted to Term Loan	367		367
Nonperforming Financial Instruments [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	10,324		10,324
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	59		59
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,349		1,349
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	2		2
Financing Receivable, Revolving	4,832		4,832
Financing Receivable, Revolving, Converted to Term Loan	146		146
Nonperforming Financial Instruments [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	1,924		1,924
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	8		8
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	296		296
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	18,328		18,328
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	1,483		1,483
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	3,643		3,643
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	0		0
Nonperforming Financial Instruments [Member] | Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	0		0
Nonperforming Financial Instruments [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	39		39
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	2,470		2,470
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	95		95
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	566		566
Nonperforming Financial Instruments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	0		0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	8,267		8,267
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,562		4,562
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	515		515
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	67		67
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	25		25
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	141		141
Financing Receivable, Revolving	9,439		9,439
Financing Receivable, Revolving, Converted to Term Loan	6,106		6,106
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	124		124
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	208		208
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	178		178
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	55		55
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	25		25
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	29		29
Financing Receivable, Revolving	7,427		7,427
Financing Receivable, Revolving, Converted to Term Loan	5,270		5,270
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member] | Commercial and Industrial Total Energy Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	518		518
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member] | Commercial Real Estate Buildings Land And Other Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	0		0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member] | Construction Loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	0		0
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	0		0
Financing Receivable, Revolving	0		0
Financing Receivable, Revolving, Converted to Term Loan	0		0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member] | Total consumer real estate loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	0		0
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	0		0
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	280		280
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	0		0
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	89		89
Financing Receivable, Revolving	961		961
Financing Receivable, Revolving, Converted to Term Loan	0		0
Financial Asset, Other than Financial Asset Acquired with Credit Deterioration | Nonperforming Financial Instruments [Member] | Consumer Loan [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	8,143		8,143
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	4,354		4,354
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	57		57
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	12		12
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	0		0
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	23		23
Financing Receivable, Revolving	1,051		1,051
Financing Receivable, Revolving, Converted to Term Loan	$ 318		$ 318

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	Jun. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	$ 17,746,311	$ 17,154,969
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	5,726,804	5,674,798
Commercial and Industrial Total Energy Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	986,571	925,729
Paycheck Protection Program [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	22,333	34,852
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	6,924,896	6,706,078
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	1,468,071	1,477,247
Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	2,157,916	1,843,539
Consumer Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income	459,720	492,726
Specific Valuation Allowances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	6,461	12,181
Specific Valuation Allowances [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	2,461	6,082
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	2,700	4,383
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	1,300	1,716
Specific Valuation Allowances [Member] | Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	0	0
Specific Valuation Allowances [Member] | Total consumer real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Specific Allocations	0	0
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	65,291	52,576
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	20,862	18,980
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	16,445	15,058
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	24,954	17,711
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	0
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	3,030	827
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	Jun. 30, 2023	Dec. 31, 2022
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	Jun. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 208	$ 386
Core deposits [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	155	310
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	$ 53	$ 76

Goodwill and Other Intangible_5

Goodwill and Other Intangible Assets - Estimated Aggregate Future Amortization Expense for Intangible Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2023	$ 105
2024	87
2025	11
2026	5
Future Amortization Expense, Total	$ 208	$ 386

Deposits - Schedule of Deposits

Deposits - Schedule of Deposits (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Deposit [Line Items]
Non-interest-bearing demand deposits	$ 14,904,614	$ 17,598,234
Interest-bearing Domestic Deposit, Savings	10,540,458	12,333,675
Interest-bearing Domestic Deposit, Money Market	11,026,368	12,227,247
Interest-bearing Domestic Deposit, Time Deposits	4,229,390	1,795,040
Total interest-bearing deposit	25,796,216	26,355,962
Total deposits	$ 40,700,830	$ 43,954,196

Deposits - Additional Informati

Deposits - Additional Information About Corporation's Deposits (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Deposit Liability [Line Items]
Deposits from foreign sources (primarily Mexico)	$ 1,036,777	$ 1,048,943
Non-interest-bearing public funds deposits	14,904,614	17,598,234
Interest-bearing public funds deposits	25,796,216	26,355,962
Total deposits not covered by deposit insurance	20,630,167	23,839,797
Time deposits not covered by deposit insurance	1,670,388	430,128
Public Funds [Member]
Deposit Liability [Line Items]
Non-interest-bearing public funds deposits	447,194	788,040
Interest-bearing public funds deposits	$ 696,521	$ 758,761

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Off-Balance-Sheet, Credit Loss, Liability, Change in Method, Credit Loss Expense (Reversal)			$ (19,000)
Lessee, Operating Lease, Liability, Payments, Due	$ 8,200	$ 8,400	16,600	$ 16,400
Significant change in expected future minimum lease payments since year end			0
Premises and Equipment
Operating Lease, Right-of-Use Asset	286,500		286,500		$ 288,800
Other Liabilities [Member]
Operating Lease, Liability	$ 320,600		$ 320,600		$ 321,900

Commitments and Contingencies_2

Commitments and Contingencies - Financial Instruments with Off-Balance-Sheet Risk (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Standby Letters of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	$ 405,900	$ 383,851
Deferred Standby Letter Of Credit Fees [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	2,176	2,236
Commitments to Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Financial instruments with off- balance-sheet risk	$ 12,208,032	$ 12,137,957

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies - Credit Losses on Off-Balance-Sheet Commitments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Off-Balance Sheet, Credit Loss, Liability	$ 54,918	$ 45,850	$ 58,593	$ 50,314
Credit loss expense (benefit)	(2,037)	4,396	(5,712)	(68)
Off-Balance Sheet, Credit Loss, Liability	$ 52,881	$ 50,246	$ 52,881	$ 50,246

Commitments and Contingencies_3

Commitments and Contingencies Commitments and Contingencies - Components of Lease Commitments Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Operating Lease, Right-of-Use Asset, Amortization Expense	$ 8,747	$ 8,209	$ 17,512	$ 16,314
Short-term lease expense	493	490	902	1,103
Non-lease components (including taxes, insurance, common maintenance, etc.)	3,662	2,748	7,043	5,768
Total operating lease expense, excluding rent	$ 12,902	$ 11,447	$ 25,457	$ 23,185

Capital and Regulatory Matter_2

Capital and Regulatory Matters - Additional Information (Detail) $ / shares in Units, $ in Thousands			3 Months Ended	6 Months Ended		12 Months Ended
	Jan. 25, 2023 USD ($)	Nov. 19, 2020 USD ($)	Jun. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) quarter $ / shares shares	Jun. 30, 2022 USD ($) shares	Dec. 31, 2022 USD ($) $ / shares shares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
CECL Transition Amount			$ 30,800	$ 30,800		$ 46,200
Treasury Stock, Shares, Acquired | shares			289,149	298,332	7,459
Purchase of treasury stock (289,149 shares QTD and 298,332 shares YTD in 2023 and 7,459 shares YTD in 2022)			$ 27,951	$ 29,124	$ 996
Maximum dividends available without prior regulatory approval			$ 967,600	$ 967,600
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		150,000
Preferred Stock, Aggregate Liquidation Preference, Value			$ 150,000	$ 150,000
Preferred stock, par value | $ / shares			$ 0.01	$ 0.01		$ 0.01
Preferred Stock, Liquidation Preference Per Share | $ / shares			$ 1,000	$ 1,000		$ 1,000
Number of Preferred Stock equivalent depositary shares | shares			40	40
Payments of Stock Issuance Costs		$ 4,500
Proceeds from Issuance of Preferred Stock and Preference Stock		$ 145,500
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	$ 25
Cullen/Frost [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Additional Tier 1 Capital beyond Common Equity Tier 1			$ 145,500	$ 145,500		$ 145,500
Preferred stock dividend rate percentage				4.45%		4.45%
Cullen/Frost [Member] | Trust Preferred Securities Tier Two Capital Allowable Portion [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust preferred securities				$ 120,000		$ 120,000
Frost Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Additional Tier 1 Capital beyond Common Equity Tier 1			0	$ 0		$ 0
stock repurchase 2023 plan
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock Repurchase Program, Authorized Amount	$ 100,000
Stock Repurchase Program, Period in Force	1 year
stock repurchase 2023 plan | Treasury Stock, Common
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Treasury Stock, Shares, Acquired | shares				288,912
Purchase of treasury stock (289,149 shares QTD and 298,332 shares YTD in 2023 and 7,459 shares YTD in 2022)				$ 28,000
prior stock repurchase plans | Treasury Stock, Common
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			$ 60,000	$ 60,000		$ 80,000

Capital and Regulatory Matter_3

Capital and Regulatory Matters - Actual and Required Capital Ratios (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Cullen/Frost [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 to Risk-Weighted Assets, Actual, Capital Amount	$ 3,943,110	$ 3,751,200
Common Equity Tier 1 to Risk-Weighted Assets, Actual , Ratio	13.42%	12.85%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 2,056,052	$ 2,042,876
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	7%	7%
Tier 1 Capital to Risk-Weighted Assets, Actual, Capital Amount	$ 4,088,562	$ 3,896,652
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio	13.92%	13.35%
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 2,496,634	$ 2,480,635
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	8.50%	8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 1,762,330	$ 1,751,036
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	$ 4,520,634	$ 4,330,982
Total Capital to Risk-Weighted Assets, Actual, Ratio	15.39%	14.84%
Total Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 3,084,077	$ 3,064,313
Total Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	10.50%	10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,937,217	$ 2,918,394
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	10%	10%
Leverage Ratio, Actual, Capital Amount	$ 4,088,562	$ 3,896,652
Leverage Ratio, Actual, Ratio	8.11%	7.29%
Leverage Ratio, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 2,016,414	$ 2,136,680
Leverage Ratio, Minimum Capital Required Plus Capital Conservation Buffer, 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	$ 3,973,809	$ 3,789,056
Common Equity Tier 1 to Risk-Weighted Assets, Actual , Ratio	13.55%	13%
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 2,053,467	$ 2,040,388
Common Equity Tier 1 to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	7%	7%
Common Equity Tier 1 to Risk-Weighted Assets, Required To Be Considered Well Capitalized, Capital Amount	$ 1,906,791	$ 1,894,646
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	$ 3,973,809	$ 3,789,056
Tier 1 Capital to Risk-Weighted Assets, Actual, Ratio	13.55%	13%
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 2,493,496	$ 2,477,614
Tier 1 Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	8.50%	8.50%
Tier 1 Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,346,820	$ 2,331,872
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	$ 4,225,881	$ 4,023,386
Total Capital to Risk-Weighted Assets, Actual, Ratio	14.41%	13.80%
Total Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 3,080,201	$ 3,060,583
Total Capital to Risk-Weighted Assets, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	10.50%	10.50%
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Capital Amount	$ 2,933,525	$ 2,914,841
Total Capital to Risk-Weighted Assets, Required to be Considered Well Capitalized, Ratio	10%	10%
Leverage Ratio, Actual, Capital Amount	$ 3,973,809	$ 3,789,056
Leverage Ratio, Actual, Ratio	7.88%	7.09%
Leverage Ratio, Minimum Capital Required Plus Capital Conservation Buffer, Capital Amount	$ 2,015,896	$ 2,136,316
Leverage Ratio, Minimum Capital Required Plus Capital Conservation Buffer, Ratio	4%	4%
Leverage Ratio, Required to be Considered Well Capitalized, Capital Amount	$ 2,519,870	$ 2,670,395
Leverage Ratio, Required to be Considered Well Capitalized, Ratio	5%	5%

Derivative Financial Instrume_3

Derivative Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Weighted-average strike rate for outstanding interest rate caps	3.32%
Approximate credit exposure related to swaps with bank customers	$ 6,800
Interest rate swaps with upstream financial institution counterparties [Member]
Derivative [Line Items]
Approximate credit exposure related to swaps with bank customers	341
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	Jun. 30, 2023	Dec. 31, 2022
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	$ 0	$ 1,614
Estimated Fair Value	0	19
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	1,162,694	1,165,812
Estimated Fair Value	78,404	70,416
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	72,833	78,798
Estimated Fair Value	(1,332)	(1,102)
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	229,804	246,442
Estimated Fair Value	14,557	15,256
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	78,789	53,570
Estimated Fair Value	1,401	1,102
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	1,156,738	1,175,563
Estimated Fair Value	(78,402)	(79,175)
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	229,804	246,442
Estimated Fair Value	$ (14,557)	$ (15,256)

Derivative Financial Instrume_5

Derivative Financial Instruments - Schedule of Weighted-Average Rates Paid and Received for Interest Rate Swaps Outstanding (Detail)	Jun. 30, 2023
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	3.96%
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	5.62%
Customer Counterparties [Member] | Weighted Average Interest Rate Paid [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – customer counterparties	5.62%
Customer Counterparties [Member] | Weighted-Average Interest Rate Received [Member]
Short-duration insurance contracts, discounted liabilities [Line Items]
Non-hedging interest rate swaps – customer counterparties	3.96%

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	Jun. 30, 2023 USD ($) bbl MMBTU	Dec. 31, 2022 USD ($) bbl MMBTU
Financial Institution Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	4,134	4,024
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	5,345	6,068
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 30,701	$ 27,082
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (21,229)	$ (53,579)
Financial Institution Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	16,694	16,539
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	9,871	15,682
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 6,668	$ 6,220
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (6,841)	$ (19,138)
Customer Counterparties [Member] | Oil Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | bbl	5,391	6,068
Oil/Natural Gas Derivative Liabilities, Notional Amount | bbl	4,088	4,024
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 21,580	$ 54,219
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (30,255)	$ (26,551)
Customer Counterparties [Member] | Natural Gas Commodity Derivative [Member]
Derivative Instruments [Line Items]
Oil/Natural Gas Derivative Assets, Notional Amount | MMBTU	9,871	15,682
Oil/Natural Gas Derivative Liabilities, Notional Amount | MMBTU	16,694	16,539
Oil/Natural Gas Derivative Assets, Estimated Fair Value	$ 6,865	$ 19,164
Oil/Natural Gas Derivative Liabilities, Estimated Fair Value	$ (6,477)	$ (6,124)

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	Jun. 30, 2023 USD ($)	Jun. 30, 2023 EUR (€)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 EUR (€)
Financial Institution Counterparties [Member] | GBP Foreign Exchange Forward
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value | $	$ 0		$ 1
Forward Contracts - Liability Estimated Fair Value | $	0		(10)
Financial Institution Counterparties [Member] | Other Assets [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Notional Amount | €		€ 0		€ 875
Financial Institution Counterparties [Member] | Other Liabilities [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Liability Notional Amount | €		0		875
Customer Counterparties [Member] | GBP Foreign Exchange Forward
Derivative Instruments [Line Items]
Forward Contracts – Assets Estimated Fair Value | $	0		10
Forward Contracts - Liability Estimated Fair Value | $	$ 0		$ (1)
Customer Counterparties [Member] | Other Assets [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Assets Notional Amount | €		0		875
Customer Counterparties [Member] | Other Liabilities [Member] | Non Designated as Hedging Instrument [Member]
Derivative Instruments [Line Items]
Forward Contracts – Liability Notional Amount | €		€ 0		€ 875

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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Interest Income on Loans [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) included in income	$ 4	$ (5)	$ 16	$ (18)
Other Non-Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) included in income	$ 4	$ 3	$ 4	$ 5

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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
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)	$ 1,002	$ 515	$ 1,712	$ 1,031
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)	1	0	0	0
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)	503	649	925	1,578
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	$ 45	$ 25	$ 63

Balance Sheet Offsetting - Fina

Balance Sheet Offsetting - Financial Instruments Eligible for Offset Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	$ 130,330	$ 118,994
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	130,330	118,994
Gross Amount Recognized, Resell agreements, Financial assets	84,650	87,150
Gross Amount Offset, Resell agreements, Financial assets	0	0
Net Amount Recognized, Resell agreements, Financial assets	84,650	87,150
Gross Amount Recognized, Financial assets	214,980	206,144
Gross Amount Offset, Financial assets	0	0
Net Amount Recognized, Financial assets	214,980	206,144
Gross Amount Recognized, Derivatives, Financial Liabilities	29,402	73,829
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	29,402	73,829
Gross Amount Recognized, Repurchase agreements, Financial liabilities	3,569,870	4,660,641
Gross Amount Offset, Repurchase agreements, Financial liabilities	0	0
Net Amount Recognized, Repurchase agreements, Financial liabilities	3,569,870	4,660,641
Gross Amount Recognized, Financial liabilities	3,599,272	4,734,470
Gross Amount Offset, Financial liabilities	0	0
Net Amount Recognized, Financial Liabilities	3,599,272	4,734,470
Loan/lease interest rate swaps and caps [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	92,961	85,691
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	92,961	85,691
Gross Amount Recognized, Derivatives, Financial Liabilities	1,332	1,102
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	1,332	1,102
Commodity swaps and options [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Gross Amount Recognized, Derivatives, Financial Assets	37,369	33,302
Gross Amount Offset, Derivatives, Financial assets	0	0
Net Amount Recognized, Derivatives, Financial assets	37,369	33,302
Gross Amount Recognized, Derivatives, Financial Liabilities	28,070	72,717
Gross Amount Offset, Derivatives, Financial liabilities	0	0
Net Amount Recognized, Derivatives, Financial liabilities	$ 28,070	72,717
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		10
Gross Amount Offset, Derivatives, Financial liabilities		0
Net Amount Recognized, Derivatives, Financial liabilities		$ 10

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	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	$ 130,330	$ 118,994
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(29,402)	(62,528)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(100,589)	(55,968)
Net Amount, Derivatives, Financial Assets	339	498
Net Amount Recognized, Resell agreements, Financial Assets	84,650	87,150
Gross Amounts Not Offset Financial Instruments, Resell Agreements	0	0
Gross Amounts Not Offset Collateral, Resell Agreements, Financial Assets	(84,650)	(87,150)
Net Amount, Financial Assets, Resell Agreements	0	0
Net Amount Recognized, Total Financial Assets	214,980	206,144
Gross Amounts Not Offset Collateral, Financial Assets	(185,239)	(143,118)
Net Amount, Financial Assets	339	498
Net Amount Recognized, Derivatives, Financial Liabilities	29,402	73,829
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(29,402)	(62,528)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(9,330)
Net Amount, Derivatives, Financial Liabilities	0	1,971
Net Amount Recognized, Repurchase Agreements, Financial Liabilities	3,569,870	4,660,641
Gross Amounts Not Offset Financial Instruments, Repurchase Agreements, Financial Liabilities	0	0
Gross Amounts Not Offset Collateral, Repurchase Agreements, Financial Liabilities	(3,569,870)	(4,660,641)
Net Amount, Repurchase Agreements, Financial Liabilities	0	0
Net Amount Recognized, Total Financial Liabilities	3,599,272	4,734,470
Gross Amounts Not Offset Collateral, Financial Liabilities	(3,569,870)	(4,669,971)
Net Amount, Financial Liabilities	0	1,971
Counterparty B
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	32,143	39,370
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(9,548)	(24,500)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(22,595)	(14,870)
Net Amount, Derivatives, Financial Assets	0	0
Net Amount Recognized, Derivatives, Financial Liabilities	9,548	24,500
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(9,548)	(24,500)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	0
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty E
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	16,312	14,430
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(896)	(47)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(15,240)	(14,131)
Net Amount, Derivatives, Financial Assets	176	252
Net Amount Recognized, Derivatives, Financial Liabilities	896	47
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(896)	(47)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	0
Net Amount, Derivatives, Financial Liabilities	0	0
Counterparty F
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	18,387	17,297
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(8,839)	(17,297)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(9,463)	0
Net Amount, Derivatives, Financial Assets	85	0
Net Amount Recognized, Derivatives, Financial Liabilities	8,839	27,747
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(8,839)	(17,297)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(8,479)
Net Amount, Derivatives, Financial Liabilities	0	1,971
Counterparty G
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	10,484	10,660
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	0	0
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(10,430)	(10,660)
Net Amount, Derivatives, Financial Assets	54	0
Net Amount Recognized, Derivatives, Financial Liabilities		0
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities		0
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities		0
Net Amount, Derivatives, Financial Liabilities		0
Other counterparties
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Net Amount Recognized, Derivatives, Financial Assets	53,004	37,237
Gross Amounts Not Offset, Financial Instruments, Total Derivatives, Financial Assets	(10,119)	(20,684)
Gross Amount Not Offset Collateral, Derivatives, Financial Assets	(42,861)	(16,307)
Net Amount, Derivatives, Financial Assets	24	246
Net Amount Recognized, Derivatives, Financial Liabilities	10,119	21,535
Gross Amounts Not Offset Financial Instruments, Total Derivatives, Financial Liabilities	(10,119)	(20,684)
Gross Amounts Not Offset Collateral, Derivatives, Financial Liabilities	0	(851)
Net Amount, Derivatives, Financial Liabilities	$ 0	$ 0

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	Jun. 30, 2023	Dec. 31, 2022
Remaining Contractual Maturity of the Securities Sold Under Agreement to Repurchase [Line Items]
Remaining contractual maturity of the agreements overnight and continuous	$ 3,569,870	$ 4,660,641
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	3,569,870	4,660,641
Securities Sold under Agreements to Repurchase, Gross	3,569,870	4,660,641
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	2,716,439	3,735,061
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	2,716,439	3,735,061
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	853,431	925,580
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	$ 853,431	$ 925,580

Stock-Based Compensation Stock-

Stock-Based Compensation Stock-Based Compensation - Narrative (Details)	Jun. 30, 2023 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	514,028

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Activity in Corporation's Active Stock Plans (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised, Number of Shares	(13,626)	(28,832)	(64,013)	(144,262)
Director deferred stock units outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares/Units			45,661
Granted, Number of Units			8,503
Ending Balance, Number of Shares/Units	54,164		54,164
Beginning Balance, Weighted-Average Grant-Date Fair Value			$ 87.15
Granted Weighted-Average Grant-Date Fair Value			103.47
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 89.71		$ 89.71
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			465,319
Granted, Number of Units			2,594
Stock Awards exercised/vested, Number of Shares			(1,957)
Forfeited/expired, Number of Shares/Units			(1,415)
Ending Balance, Number of Shares/Units	464,541		464,541
Beginning Balance, Weighted-Average Grant-Date Fair Value			$ 105.36
Granted Weighted-Average Grant-Date Fair Value			128.42
Stock Award Exercised/Vested, Weighted Average Grant Date Fair Value			91.96
Forfeited/Expired, Weighted-Average Price			116.02
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 105.52		$ 105.52
Stock Options Outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares			616,227
Stock options exercised, Number of Shares			(33,905)
Ending Balance, Number of Shares	582,322		582,322
Beginning Balance, Weighted-Average Exercise Price			$ 71.27
Stock options exercised, Weighted-Average Exercise Price			72.13
Ending Balance, Weighted-Average Exercise Price	$ 71.22		$ 71.22
Maximum [Member] | Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning Balance, Number of Shares/Units			213,749
Stock Awards exercised/vested, Number of Shares			(28,151)
Forfeited/expired, Number of Shares/Units			(18,254)
Ending Balance, Number of Shares/Units	167,344		167,344
Beginning Balance, Weighted-Average Grant-Date Fair Value			$ 96.20
Stock Award Exercised/Vested, Weighted Average Grant Date Fair Value			85.74
Forfeited/Expired, Weighted-Average Price			85.74
Ending Balance, Weighted-Average Grant-Date Fair Value	$ 99.10		$ 99.10

Stock-Based Compensation - Shar

Stock-Based Compensation - Shares Issued in Connection with Stock Compensation Awards (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-Based Payment Arrangement [Abstract]
New shares issued from available authorized shares	0	0	49,887	0
Shares issued from available treasury stock	13,626	28,832	14,126	144,262
Proceeds from stock option exercises	$ 946	$ 751	$ 2,446	$ 6,490

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 4,793	$ 3,418	$ 9,535	$ 5,530
Income tax benefit	800	612	1,868	1,320
Non-Vested Stock Awards/Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	2,864	2,291	6,171	4,649
Director deferred stock units outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	880	720	880	720
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock or Unit Expense	$ 1,049	$ 407	$ 2,484	$ 161

Stock-Based Compensation - Unre

Stock-Based Compensation - Unrecognized Stock-Based Compensation Expense (Detail) $ in Thousands	Jun. 30, 2023 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-vested stock units	$ 15,768
Performance stock units	7,029
Total	$ 22,797

Earnings Per Common Share - Bas

Earnings Per Common Share - Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net income	$ 162,118	$ 119,114	$ 339,771	$ 218,216
Less: Preferred stock dividends	1,669	1,669	3,338	3,338
Net income available to common shareholders	160,449	117,445	336,433	214,878
Less: Earnings allocated to participating securities	1,645	1,036	3,468	1,888
Distributed earnings allocated to common stock	55,783	48,092	111,789	96,143
Undistributed earnings allocated to common stock	103,021	68,317	221,176	116,847
Net earnings allocated to common stock	$ 158,804	$ 116,409	$ 332,965	$ 212,990
Weighted-average shares outstanding for basic earnings per common share	64,240,789	64,112,828	64,306,809	64,082,185
Dilutive effect of stock compensation	187,172	354,401	225,267	382,395
Weighted-average shares outstanding for diluted earnings per common share	64,427,961	64,467,229	64,532,076	64,464,580

Defined Benefit Plans Additiona

Defined Benefit Plans Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2023 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		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Retirement Benefits [Abstract]
Expected return on plan assets, net of expenses	$ (2,740)	$ (3,492)	$ (5,480)	$ (6,983)
Interest cost on projected benefit obligation	1,746	1,004	3,492	2,008
Net amortization and deferral	870	741	1,740	1,482
Net periodic expense (benefit)	$ (124)	$ (1,747)	$ (248)	$ (3,493)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Net	$ 365.4		$ 374.4
Valuation allowance	$ 0
U.S. federal statutory income tax rate, percent	21%	21%
Unrecognized tax benefits	$ 0	$ 0

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Current income tax expense	$ 32,413	$ 22,646	$ 67,408	$ 35,705
Deferred income tax expense (benefit)	(680)	(1,972)	(2,489)	(2,404)
Income tax expense, as reported	$ 31,733	$ 20,674	$ 64,919	$ 33,301
Effective tax rate	16.40%	14.80%	16%	13.20%

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - Component of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Equity [Abstract]
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Before Tax Amount	$ (206,863)	$ (636,523)	$ 53,406	$ (1,547,318)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Before Tax Amount	(162)	(189)	(322)	(398)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Before Tax Amount	(33)	0	(54)	0
Total securities available for sale and transferred securities, before tax amount	(207,058)	(636,712)	53,030	(1,547,716)
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit), before tax amount	870	741	1,740	1,482
Total defined-benefit post-retirement benefit plans	870	741	1,740	1,482
Total other comprehensive income (loss), before tax	(206,188)	(635,971)	54,770	(1,546,234)
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Tax Expense (Benefit)	(43,441)	(133,670)	11,215	(324,937)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Tax Expense (Benefit)	(34)	(40)	(67)	(84)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Tax Expense (Benefit)	(7)	0	(11)	0
Total securities available for sale and transferred securities, Tax Expense (Benefit)	(43,482)	(133,710)	11,137	(325,021)
Reclassification adjustment for net amortization of actuarial gain/loss included in net income as a component of net periodic cost (benefit), Tax Expense (Benefit)	183	155	366	311
Total defined-benefit post-retirement benefit plans, Tax Expense (Benefit)	183	155	366	311
Total other comprehensive income (loss), Tax Expense (Benefit)	(43,299)	(133,555)	11,503	(324,710)
Securities available for sale and transferred securities, Change in net unrealized gain/loss during the period, Net of Tax	(163,422)	(502,853)	42,191	(1,222,381)
Securities available for sale and transferred securities, Change in net unrealized gain on securities transferred to held to maturity, Net of Tax	(128)	(149)	(255)	(314)
Securities available for sale and transferred securities, Reclassification adjustment for net (gains) losses included in net income, Net of Tax	(26)	0	(43)	0
Total securities available for sale and transferred securities, Net of Tax	(163,576)	(503,002)	41,893	(1,222,695)
Reclassification adjustment for net amortization of actuarial gain/lloss included in net income as a component of net periodic cost (benefit), Net of Tax	687	586	1,374	1,171
Total defined-benefit post-retirement benefit plans, Net of Tax Amount	687	586	1,374	1,171
Other comprehensive income (loss), net of tax	$ (162,889)	$ (502,416)	$ 43,267	$ (1,221,524)

Other Comprehensive Income - Sc

Other Comprehensive Income - Schedule of Accumulated Other Comprehensive Income, Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			$ (1,348,294)
Other comprehensive income (loss), net of tax	$ (162,889)	$ (502,416)	43,267	$ (1,221,524)
Ending Balance	(1,305,027)		(1,305,027)
Securities Available For Sale [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(1,313,791)	380,209
Other comprehensive income (loss) before reclassifications			41,936	(1,222,695)
Reclassification of amounts included in net income			(43)	0
Other comprehensive income (loss), net of tax			41,893	(1,222,695)
Ending Balance	(1,271,898)	(842,486)	(1,271,898)	(842,486)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(34,503)	(32,891)
Other comprehensive income (loss) before reclassifications			0	0
Reclassification of amounts included in net income			1,374	1,171
Other comprehensive income (loss), net of tax			1,374	1,171
Ending Balance	(33,129)	(31,720)	(33,129)	(31,720)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance			(1,348,294)	347,318
Other comprehensive income (loss) before reclassifications			41,936	(1,222,695)
Reclassification of amounts included in net income			1,331	1,171
Other comprehensive income (loss), net of tax			43,267	(1,221,524)
Ending Balance	$ (1,305,027)	$ (874,206)	$ (1,305,027)	$ (874,206)

Operating Segments - Additional

Operating Segments - Additional Information (Detail) - Segment	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting [Abstract]
Number of primary operating segments	2	2

Operating Segments - Summary of

Operating Segments - Summary of Operating Results by Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	$ 385,266	$ 288,208	$ 785,086	$ 537,279
Credit loss expense	9,901	0	19,005	0
Total non-interest income	103,528	97,927	208,793	199,317
Total non-interest expense	285,042	246,347	570,184	485,079
Income (loss) before income taxes	193,851	139,788	404,690	251,517
Income tax expense (benefit)	31,733	20,674	64,919	33,301
Net income (loss)	162,118	119,114	339,771	218,216
Preferred stock dividends	1,669	1,669	3,338	3,338
Net income (loss) available to common shareholders	160,449	117,445	336,433	214,878
Revenues from (expenses to) external customers	488,794	386,135	993,879	736,596
Bank
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	385,720	289,186	785,857	539,305
Credit loss expense	9,901	1	19,003	0
Total non-interest income	57,808	55,397	121,451	114,103
Total non-interest expense	246,927	211,044	496,794	417,582
Income (loss) before income taxes	186,700	133,538	391,511	235,826
Income tax expense (benefit)	30,636	19,821	62,754	30,835
Net income (loss)	156,064	113,717	328,757	204,991
Preferred stock dividends	0	0	0	0
Net income (loss) available to common shareholders	156,064	113,717	328,757	204,991
Revenues from (expenses to) external customers	443,528	344,583	907,308	653,408
Frost Wealth Advisors [Member]
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	2,090	958	3,744	1,658
Credit loss expense	0	(1)	2	0
Total non-interest income	46,147	43,054	88,185	86,283
Total non-interest expense	35,558	33,158	69,505	64,068
Income (loss) before income taxes	12,679	10,855	22,422	23,873
Income tax expense (benefit)	2,663	2,279	4,709	5,013
Net income (loss)	10,016	8,576	17,713	18,860
Preferred stock dividends	0	0	0	0
Net income (loss) available to common shareholders	10,016	8,576	17,713	18,860
Revenues from (expenses to) external customers	48,237	44,012	91,929	87,941
Non-Banks [Member]
Segment Reporting Information [Line Items]
Interest Income (Expense), Net	(2,544)	(1,936)	(4,515)	(3,684)
Credit loss expense	0	0	0	0
Total non-interest income	(427)	(524)	(843)	(1,069)
Total non-interest expense	2,557	2,145	3,885	3,429
Income (loss) before income taxes	(5,528)	(4,605)	(9,243)	(8,182)
Income tax expense (benefit)	(1,566)	(1,426)	(2,544)	(2,547)
Net income (loss)	(3,962)	(3,179)	(6,699)	(5,635)
Preferred stock dividends	1,669	1,669	3,338	3,338
Net income (loss) available to common shareholders	(5,631)	(4,848)	(10,037)	(8,973)
Revenues from (expenses to) external customers	$ (2,971)	$ (2,460)	$ (5,358)	$ (4,753)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-financial assets or non-financial liabilities	$ 0	$ 0	$ 0	$ 0
Remeasured and reported at fair value	0	$ 0	0	$ 0
Financial instruments using fair value measurement option	$ 0		$ 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	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	$ 17,249,257	$ 18,243,605
Trading account securities	32,517	28,045
Derivative assets	130,330	118,994
Derivative liabilities	29,402	73,829
Interest rate swaps, caps and floors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	94,362	86,793
Derivative liabilities	94,291	95,533
Commodity swaps and options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	65,814	106,685
Derivative liabilities	64,802	105,392
Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		11
Derivative liabilities		11
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	5,072,888	5,051,587
Trading account securities	27,546	25,879
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	6,792,775	6,376,236
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	5,341,016	6,773,355
Trading account securities	4,971	2,166
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at estimated fair value	42,578	42,427
Level 1 [Member] | Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		11
Derivative liabilities		11
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	5,072,888	5,051,587
Trading account securities	27,546	25,879
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	94,362	86,793
Derivative liabilities	94,291	95,533
Level 2 [Member] | Commodity swaps and options [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	65,814	106,685
Derivative liabilities	64,802	105,392
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	6,792,775	6,376,236
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	5,341,016	6,773,355
Trading account securities	4,971	2,166
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	$ 42,578	$ 42,427

Fair Value Measurements - Impai

Fair Value Measurements - Impaired Loans Remeasured and Reported at Fair Value of Underlying Collateral (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Jun. 30, 2022
Level 2 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Carrying value of impaired loans before allocations	$ 19,064	$ 5,454
Impaired Financing Receivable, Related Allowance	(1,300)	(1,327)
Loans receivable, fair value disclosure	17,764	4,127
Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Carrying value of impaired loans before allocations	20,171	3,614
Impaired Financing Receivable, Related Allowance	(2,100)
Impaired Financing Receivable, Reversal of Specific Valuation Allowance Allocations		6,877
Loans receivable, fair value disclosure	$ 18,071	$ 10,491

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 7,107,336	$ 12,028,132	$ 13,658,585	$ 16,583,000
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	3,691,220	2,639,083
Loans, net	17,512,692	16,927,348
Deposits	40,700,830	43,954,196
Federal funds purchased	13,525	51,650
Repurchase agreements	3,569,870	4,660,641
Junior subordinated deferrable interest debentures	123,098	123,069
Subordinated notes	99,413	99,335
Carrying Amount [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	7,107,336	12,028,132
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	3,691,220	2,639,083
Cash surrender value of life insurance policies	190,575	190,188
Accrued interest receivable	236,967	243,682
Deposits	40,700,830	43,954,196
Federal funds purchased	13,525	51,650
Repurchase agreements	3,569,870	4,660,641
Junior subordinated deferrable interest debentures	123,098	123,069
Subordinated notes	99,413	99,335
Accrued interest payable	40,523	18,444
Carrying Amount [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	17,512,692	16,927,348
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	7,107,336	12,028,132
Securities held to maturity, net of allowance for credit losses of $267 at June 30, 2023 and $158 at December 31, 2022	3,543,929	2,467,865
Cash surrender value of life insurance policies	190,575	190,188
Accrued interest receivable	236,967	243,682
Deposits	40,683,556	43,920,741
Federal funds purchased	13,525	51,650
Repurchase agreements	3,569,870	4,660,641
Junior subordinated deferrable interest debentures	123,712	123,712
Subordinated notes	94,571	97,014
Accrued interest payable	40,523	18,444
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net	$ 16,933,702	$ 16,343,417