Annual report pursuant to Section 13 and 15(d)

SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details)

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SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities $ 3,448,784 $ 2,439,247
Gross Unrealized Gains 65,198 103,512
Gross Unrealized (Losses) (32,332) (2,340)
Total AFS securities, Estimated Fair Value 3,481,650 2,540,419
U.S. government and agency securities    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 73,830 13,009
Gross Unrealized Gains 179 437
Gross Unrealized (Losses) (160) (52)
Total AFS securities, Estimated Fair Value 73,849 13,394
Obligations of states and political subdivisions    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 971,126 786,466
Gross Unrealized Gains 39,343 50,878
Gross Unrealized (Losses) (2,073) (18)
Total AFS securities, Estimated Fair Value 1,008,396 837,326
Corporate and other bonds    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 150,201 148,747
Gross Unrealized Gains 3,353 2,430
Gross Unrealized (Losses) (178) (99)
Total AFS securities, Estimated Fair Value 153,376 151,078
Commercial    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 468,893 372,259
Gross Unrealized Gains 6,900 16,444
Gross Unrealized (Losses) (4,636) (19)
Total AFS securities, Estimated Fair Value 471,157 388,684
Commercial | Agency    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 361,806 321,015
Gross Unrealized Gains 6,761 16,277
Gross Unrealized (Losses) (4,215) (2)
Total AFS securities, Estimated Fair Value 364,352 337,290
Commercial | Non-agency    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 107,087 51,244
Gross Unrealized Gains 139 167
Gross Unrealized (Losses) (421) (17)
Total AFS securities, Estimated Fair Value 106,805 51,394
Residential    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 1,783,094 1,117,141
Gross Unrealized Gains 15,423 33,323
Gross Unrealized (Losses) (25,285) (2,152)
Total AFS securities, Estimated Fair Value 1,773,232 1,148,312
Residential | Agency    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 1,691,651 1,012,237
Gross Unrealized Gains 15,180 31,816
Gross Unrealized (Losses) (24,337) (1,946)
Total AFS securities, Estimated Fair Value 1,682,494 1,042,107
Residential | Non-agency    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 91,443 104,904
Gross Unrealized Gains 243 1,507
Gross Unrealized (Losses) (948) (206)
Total AFS securities, Estimated Fair Value 90,738 106,205
Other securities    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 1,640 1,625
Gross Unrealized Gains 0 0
Gross Unrealized (Losses) 0 0
Total AFS securities, Estimated Fair Value $ 1,640 $ 1,625