v3.26.1
Segment information - Information about Company's Segments (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Net Interest Income $ 1,792,000 $ 1,713,000 $ 3,544,000 $ 3,408,000
Noninterest income 740,000 683,000 1,429,000 1,294,000
Provision for credit losses 120,000 125,000 260,000 255,000
Provision for credit losses 120,000 105,000 245,000 235,000
Salaries and employee benefits 826,000 813,000 1,740,000 1,700,000
Depreciation and amortization     156,000 164,000
Income before taxes 1,063,000 935,000 1,926,000 1,696,000
Income tax expense (benefit) 245,000 219,000 444,000 396,000
Net income (loss) 818,000 716,000 1,482,000 1,300,000
Operating Segments        
Segment Reporting [Line Items]        
Net Interest Income 1,792,000 1,713,000 3,544,000 3,408,000
Noninterest income 740,000 683,000 1,429,000 1,294,000
Total revenue 2,532,000 2,396,000 4,973,000 4,702,000
Salaries and employee benefits 826,000 813,000 1,740,000 1,700,000
Depreciation and amortization 93,000 124,000 190,000 254,000
Other direct expenses 430,000 399,000 857,000 797,000
Indirect expense 0 0 0 0
Income before taxes 1,063,000 935,000 1,926,000 1,696,000
Income tax expense (benefit) 245,000 219,000 444,000 396,000
Average total assets 216,532,000 210,261,000 215,186,000 209,296,000
Commercial Bank | Operating Segments        
Segment Reporting [Line Items]        
Net Interest Income 559,000 531,000 1,094,000 1,060,000
Noninterest income 193,000 205,000 386,000 378,000
Total revenue 752,000 736,000 1,480,000 1,438,000
Provision for credit losses 23,000 60,000 52,000 96,000
Salaries and employee benefits 145,000 150,000 290,000 301,000
Depreciation and amortization 11,000 11,000 21,000 21,000
Other direct expenses 73,000 73,000 151,000 140,000
Indirect expense 134,000 129,000 261,000 252,000
Income before taxes 366,000 313,000 705,000 628,000
Income tax expense (benefit) 95,000 82,000 184,000 166,000
Net income (loss) 271,000 231,000 521,000 462,000
Average total assets 80,930,000 78,497,000 79,873,000 78,927,000
Retail Bank | Operating Segments        
Segment Reporting [Line Items]        
Net Interest Income 974,000 988,000 1,924,000 1,960,000
Noninterest income 236,000 234,000 453,000 442,000
Total revenue 1,210,000 1,222,000 2,377,000 2,402,000
Provision for credit losses 70,000 71,000 152,000 150,000
Salaries and employee benefits 203,000 201,000 400,000 397,000
Depreciation and amortization 34,000 60,000 70,000 122,000
Other direct expenses 107,000 95,000 210,000 194,000
Indirect expense 313,000 292,000 602,000 571,000
Income before taxes 483,000 503,000 943,000 968,000
Income tax expense (benefit) 123,000 128,000 239,000 246,000
Net income (loss) 360,000 375,000 704,000 722,000
Average total assets 60,204,000 55,995,000 59,516,000 55,193,000
Institutional Services and Wealth Management | Operating Segments        
Segment Reporting [Line Items]        
Net Interest Income 149,000 166,000 305,000 337,000
Noninterest income 235,000 225,000 456,000 434,000
Total revenue 384,000 391,000 761,000 771,000
Provision for credit losses 0 2,000 0 5,000
Salaries and employee benefits 112,000 107,000 221,000 213,000
Depreciation and amortization 2,000 2,000 4,000 4,000
Other direct expenses 28,000 26,000 63,000 52,000
Indirect expense 81,000 82,000 161,000 163,000
Income before taxes 161,000 172,000 312,000 334,000
Income tax expense (benefit) 41,000 44,000 80,000 85,000
Net income (loss) 120,000 128,000 232,000 249,000
Average total assets 4,728,000 4,272,000 4,736,000 4,187,000
All Other | Operating Segments        
Segment Reporting [Line Items]        
Net Interest Income 110,000 28,000 221,000 51,000
Noninterest income 76,000 19,000 134,000 40,000
Total revenue 186,000 47,000 355,000 91,000
Provision for credit losses 27,000 (8,000) 56,000 4,000
Salaries and employee benefits 366,000 355,000 829,000 789,000
Depreciation and amortization 46,000 51,000 95,000 107,000
Other direct expenses 222,000 205,000 433,000 411,000
Indirect expense (528,000) (503,000) (1,024,000) (986,000)
Income before taxes 53,000 (53,000) (34,000) (234,000)
Income tax expense (benefit) (14,000) (35,000) (59,000) (101,000)
Net income (loss) 67,000 (18,000) 25,000 (133,000)
Average total assets $ 70,670,000 $ 71,497,000 $ 71,061,000 $ 70,989,000