v3.22.4
Operating Segments (Summary of Operating Results by Segment) (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Segment Reporting Information [Line Items]      
Net interest income (expense) $ 1,291,283 $ 984,867 $ 976,001
Credit loss expense 3,000 63 241,230
Non-interest income 404,818 386,728 465,454
Non-interest expense 1,024,274 881,994 848,904
Income before income taxes 668,827 489,538 351,321
Income tax expense (benefit) 89,677 46,459 20,170
Net income 579,150 443,079 331,151
Preferred stock dividends 6,675 7,157 2,016
Redemption of preferred stock 0 0 5,514
Net income available to common shareholders 572,475 435,922 323,621
Revenues from (expenses to) external customers 1,696,101 1,371,595 1,441,455
Average assets 51,513,000 45,983,000 37,961,000
Banking [Member]      
Segment Reporting Information [Line Items]      
Net interest income (expense) 1,295,467 989,870 981,441
Credit loss expense 3,000 54 241,230
Non-interest income 230,876 220,662 321,136
Non-interest expense 886,421 753,719 718,519
Income before income taxes 636,922 456,759 342,828
Income tax expense (benefit) 85,127 41,483 20,347
Net income 551,795 415,276 322,481
Preferred stock dividends 0 0 0
Redemption of preferred stock     0
Net income available to common shareholders 551,795 415,276 322,481
Revenues from (expenses to) external customers 1,526,343 1,210,532 1,302,577
Average assets 51,448,000 45,903,000 37,892,000
Frost Wealth Advisors [Member]      
Segment Reporting Information [Line Items]      
Net interest income (expense) 4,645 2,138 2,776
Credit loss expense 0 9 0
Non-interest income 175,874 167,442 145,268
Non-interest expense 132,009 122,972 123,630
Income before income taxes 48,510 46,599 24,414
Income tax expense (benefit) 10,187 9,786 5,127
Net income 38,323 36,813 19,287
Preferred stock dividends 0 0 0
Redemption of preferred stock     0
Net income available to common shareholders 38,323 36,813 19,287
Revenues from (expenses to) external customers 180,519 169,580 148,044
Average assets 57,000 70,000 59,000
Non-Banks [Member]      
Segment Reporting Information [Line Items]      
Net interest income (expense) (8,829) (7,141) (8,216)
Credit loss expense 0 0 0
Non-interest income (1,932) (1,376) (950)
Non-interest expense 5,844 5,303 6,755
Income before income taxes (16,605) (13,820) (15,921)
Income tax expense (benefit) (5,637) (4,810) (5,304)
Net income (10,968) (9,010) (10,617)
Preferred stock dividends 6,675 7,157 2,016
Redemption of preferred stock     5,514
Net income available to common shareholders (17,643) (16,167) (18,147)
Revenues from (expenses to) external customers (10,761) (8,517) (9,166)
Average assets $ 8,000 $ 10,000 $ 10,000