v3.25.2
Operating Segments - Summary of Operating Results by Segment (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Segment Reporting Information [Line Items]        
Interest income $ 601,958 $ 596,285 $ 1,187,075 $ 1,181,785
Interest expense 172,354 199,573 341,251 395,022
Net interest income (expense) 429,604 396,712 845,824 786,763
Credit loss expense 13,129 15,787 26,199 29,437
Net interest income after credit loss expense 416,475 380,925 819,625 757,326
Trust and investment management fees 43,669 41,404 86,600 80,489
Service charges on deposit accounts 29,151 26,114 57,772 50,909
Insurance commissions and fees 13,879 13,919 34,898 32,215
Interchange and card transaction fees 5,619 5,351 11,021 9,825
Other charges, commissions, and fees 13,967 13,020 27,553 25,080
Net gain (loss) on securities transactions 0 0 (14) 0
Other 10,988 11,382 23,454 24,049
Total non-interest income 117,273 111,190 241,284 222,567
Salaries and wages 162,149 151,237 323,006 299,237
Employee benefits 32,826 28,802 74,983 64,772
Net occupancy 34,640 32,374 67,917 64,152
Technology, furniture, and equipment 40,572 35,951 80,690 70,946
Deposit insurance 6,590 8,383 13,774 23,107
Other 70,351 60,217 134,824 120,967
Total non-interest expense 347,128 316,964 695,194 643,181
Income (loss) before income taxes 186,620 175,151 365,715 336,712
Income tax expense (benefit) 29,617 29,652 57,790 55,523
Net income (loss) 157,003 145,499 307,925 281,189
Preferred stock dividends 1,669 1,669 3,338 3,338
Net income (loss) available to common shareholders 155,334 143,830 304,587 277,851
Revenues from (expenses to) external customers 546,877 507,902 1,087,108 1,009,330
Average assets (in millions) 51,191,000 48,960,000 51,064,000 49,142,000
Bank        
Segment Reporting Information [Line Items]        
Interest income 599,875 594,264 1,183,116 1,177,993
Interest expense 169,150 202,924 334,850 387,918
Net interest income (expense) 430,725 398,270 848,266 790,075
Credit loss expense 13,129 15,787 26,199 29,437
Net interest income after credit loss expense 417,596 382,483 822,067 760,638
Trust and investment management fees 0 0 0 0
Service charges on deposit accounts 29,149 26,111 57,767 50,903
Insurance commissions and fees 13,879 13,919 34,898 32,215
Interchange and card transaction fees 5,619 5,351 11,021 9,825
Other charges, commissions, and fees 8,031 7,364 15,437 14,489
Net gain (loss) on securities transactions 0 0 (14) 0
Other 9,002 9,433 20,387 21,126
Total non-interest income 65,680 62,178 139,496 128,558
Salaries and wages 142,089 132,831 283,181 262,863
Employee benefits 29,244 25,663 66,582 57,537
Net occupancy 30,893 28,872 60,629 57,008
Technology, furniture, and equipment 39,178 34,530 77,735 68,045
Deposit insurance 6,579 8,353 13,750 23,066
Other 54,412 45,947 105,240 94,507
Total non-interest expense 302,395 276,196 607,117 563,026
Income (loss) before income taxes 180,881 168,465 354,446 326,170
Income tax expense (benefit) 28,891 28,819 56,417 54,454
Net income (loss) 151,990 139,646 298,029 271,716
Preferred stock dividends 0 0 0 0
Net income (loss) available to common shareholders 151,990 139,646 298,029 271,716
Revenues from (expenses to) external customers 496,405 460,448 987,762 918,633
Average assets (in millions) 51,117,000 48,897,000 50,987,000 49,074,000
Frost Wealth Advisors [Member]        
Segment Reporting Information [Line Items]        
Interest income 2,083 2,021 3,959 3,792
Interest expense 99 114 188 216
Net interest income (expense) 1,984 1,907 3,771 3,576
Credit loss expense 0 0 0 0
Net interest income after credit loss expense 1,984 1,907 3,771 3,576
Trust and investment management fees 43,844 41,950 87,388 81,530
Service charges on deposit accounts 2 3 5 6
Insurance commissions and fees 0 0 0 0
Interchange and card transaction fees 0 0 0 0
Other charges, commissions, and fees 5,936 5,656 12,116 10,591
Net gain (loss) on securities transactions 0 0 0 0
Other 1,928 1,880 2,951 2,788
Total non-interest income 51,710 49,489 102,460 94,915
Salaries and wages 19,664 18,001 39,033 35,563
Employee benefits 3,557 3,112 8,351 7,182
Net occupancy 3,747 3,502 7,288 7,144
Technology, furniture, and equipment 1,344 1,368 2,852 2,800
Deposit insurance 11 30 24 41
Other 13,414 11,862 26,054 23,118
Total non-interest expense 41,737 37,875 83,602 75,848
Income (loss) before income taxes 11,957 13,521 22,629 22,643
Income tax expense (benefit) 2,511 2,839 4,752 4,755
Net income (loss) 9,446 10,682 17,877 17,888
Preferred stock dividends 0 0 0 0
Net income (loss) available to common shareholders 9,446 10,682 17,877 17,888
Revenues from (expenses to) external customers 53,694 51,396 106,231 98,491
Average assets (in millions) 65,000 54,000 68,000 59,000
Non-Banks [Member]        
Segment Reporting Information [Line Items]        
Interest income 0 0 0 0
Interest expense 3,105 (3,465) 6,213 6,888
Net interest income (expense) (3,105) (3,465) (6,213) (6,888)
Credit loss expense 0 0 0 0
Net interest income after credit loss expense (3,105) (3,465) (6,213) (6,888)
Trust and investment management fees (175) (546) (788) (1,041)
Service charges on deposit accounts 0 0 0 0
Insurance commissions and fees 0 0 0 0
Interchange and card transaction fees 0 0 0 0
Other charges, commissions, and fees 0 0 0 0
Net gain (loss) on securities transactions 0 0 0 0
Other 58 69 116 135
Total non-interest income (117) (477) (672) (906)
Salaries and wages 396 405 792 811
Employee benefits 25 27 50 53
Net occupancy 0 0 0 0
Technology, furniture, and equipment 50 53 103 101
Deposit insurance 0 0 0 0
Other 2,525 2,408 3,530 3,342
Total non-interest expense 2,996 2,893 4,475 4,307
Income (loss) before income taxes (6,218) (6,835) (11,360) (12,101)
Income tax expense (benefit) (1,785) (2,006) (3,379) (3,686)
Net income (loss) (4,433) (4,829) (7,981) (8,415)
Preferred stock dividends 1,669 1,669 3,338 3,338
Net income (loss) available to common shareholders (6,102) (6,498) (11,319) (11,753)
Revenues from (expenses to) external customers (3,222) (3,942) (6,885) (7,794)
Average assets (in millions) $ 9,000 $ 9,000 $ 9,000 $ 9,000