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v3.20.4

Operating Segments (Summary of Operating Results by Segment) (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Segment Reporting Information [Line Items] |  |  |
Net interest income (expense) | $ 976,001 | $ 1,004,005 | $ 957,892
Credit loss expense | 241,230 | 33,759 | 21,685
Non-interest income | 465,454 | 363,902 | 351,286
Non-interest expense | 848,904 | 834,679 | 778,812
Income before income taxes | 351,321 | 499,469 | 508,681
Income tax expense (benefit) | 20,170 | 55,870 | 53,763
Net income | 331,151 | 443,599 | 454,918
Preferred stock dividends | 2,016 | 8,063 | 8,063
Redemption of preferred stock | 5,514 | 0 | 0
Net income available to common shareholders | 323,621 | 435,536 | 446,855
Revenues from (expenses to) external customers | 1,441,455 | 1,367,907 | 1,309,178
Average assets | 37,961,000 | 32,086,000 | 31,030,000
Banking [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net interest income (expense) | 981,441 | 1,010,368 | 963,757
Credit loss expense | 241,230 | 33,758 | 21,685
Non-interest income | 321,136 | 218,447 | 213,763
Non-interest expense | 718,519 | 703,121 | 657,376
Income before income taxes | 342,828 | 491,936 | 498,459
Income tax expense (benefit) | 20,347 | 55,520 | 52,928
Net income | 322,481 | 436,416 | 445,531
Preferred stock dividends | 0 | 0 | 0
Redemption of preferred stock | 0 |  |
Net income available to common shareholders | 322,481 | 436,416 | 445,531
Revenues from (expenses to) external customers | 1,302,577 | 1,228,815 | 1,177,520
Average assets | 37,892,000 | 32,019,000 | 30,964,000
Frost Wealth Advisors [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net interest income (expense) | 2,776 | 4,001 | 4,083
Credit loss expense | 0 | 1 | 0
Non-interest income | 145,268 | 145,905 | 138,045
Non-interest expense | 123,630 | 124,622 | 114,166
Income before income taxes | 24,414 | 25,283 | 27,962
Income tax expense (benefit) | 5,127 | 5,308 | 5,872
Net income | 19,287 | 19,975 | 22,090
Preferred stock dividends | 0 | 0 | 0
Redemption of preferred stock | 0 |  |
Net income available to common shareholders | 19,287 | 19,975 | 22,090
Revenues from (expenses to) external customers | 148,044 | 149,906 | 142,128
Average assets | 59,000 | 56,000 | 54,000
Non-Banks [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Net interest income (expense) | (8,216) | (10,364) | (9,948)
Credit loss expense | 0 | 0 | 0
Non-interest income | (950) | (450) | (522)
Non-interest expense | 6,755 | 6,936 | 7,270
Income before income taxes | (15,921) | (17,750) | (17,740)
Income tax expense (benefit) | (5,304) | (4,958) | (5,037)
Net income | (10,617) | (12,792) | (12,703)
Preferred stock dividends | 2,016 | 8,063 | 8,063
Redemption of preferred stock | 5,514 |  |
Net income available to common shareholders | (18,147) | (20,855) | (20,766)
Revenues from (expenses to) external customers | (9,166) | (10,814) | (10,470)
Average assets | $ 10,000 | $ 11,000 | $ 12,000

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