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Loans and Allowances for Credit Losses, By Aging Category (Details) - USD ($) | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Financing receivable, recorded investment, aging [Abstract] |  |
Current | $ 21,938,836,000 | $ 21,308,989,000
Nonaccrual | 172,466,000 | 163,247,000
Total | 22,285,367,000 | 21,656,730,000
Commercial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 14,297,027,000 | 13,521,894,000
Nonaccrual | 111,706,000 | 99,841,000
Total | 14,424,625,000 | 13,636,078,000
Commercial [Member] | Energy [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 4,025,375,000 | 3,542,839,000
Nonaccrual | 88,894,000 | 47,494,000
Total | 4,114,269,000 | 3,590,333,000
Commercial [Member] | Services [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 3,249,994,000 | 3,237,578,000
Nonaccrual | 6,119,000 | 8,567,000
Total | 3,266,249,000 | 3,258,192,000
Commercial [Member] | Wholesale/retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 1,844,203,000 | 1,619,290,000
Nonaccrual | 1,504,000 | 1,316,000
Total | 1,848,617,000 | 1,621,158,000
Commercial [Member] | Manufacturing [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 687,358,000 | 721,204,000
Nonaccrual | 8,741,000 | 8,919,000
Total | 698,408,000 | 730,521,000
Commercial [Member] | Healthcare [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 3,026,838,000 | 2,781,944,000
Nonaccrual | 5,978,000 | 16,538,000
Total | 3,032,968,000 | 2,799,277,000
Commercial [Member] | Public finance [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 744,840,000 | 804,550,000
Nonaccrual | 0 | 0
Total | 744,840,000 | 804,550,000
Commercial [Member] | Other commercial and industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 718,419,000 | 814,489,000
Nonaccrual | 470,000 | 17,007,000
Total | 719,274,000 | 832,047,000
Commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 4,595,305,000 | 4,725,669,000
Nonaccrual | 23,185,000 | 21,621,000
Total | 4,626,057,000 | 4,764,813,000
Commercial real estate [Member] | Residential construction and land development [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 134,947,000 | 147,705,000
Nonaccrual | 350,000 | 350,000
Total | 135,361,000 | 148,584,000
Commercial real estate [Member] | Retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 779,037,000 | 884,424,000
Nonaccrual | 20,132,000 | 20,279,000
Total | 799,169,000 | 919,082,000
Commercial real estate [Member] | Office [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 1,013,420,000 | 1,072,920,000
Nonaccrual | 855,000 | 0
Total | 1,014,275,000 | 1,072,920,000
Commercial real estate [Member] | Multifamily [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 1,318,148,000 | 1,287,483,000
Nonaccrual | 286,000 | 301,000
Total | 1,324,839,000 | 1,288,065,000
Commercial real estate [Member] | Industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 872,627,000 | 776,898,000
Nonaccrual | 909,000 | 0
Total | 873,536,000 | 778,106,000
Commercial real estate [Member] | Other commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 477,126,000 | 556,239,000
Nonaccrual | 653,000 | 691,000
Total | 478,877,000 | 558,056,000
Residential mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 1,929,616,000 | 2,037,128,000
Nonaccrual | 37,304,000 | 41,555,000
Total | 2,117,303,000 | 2,230,033,000
Residential mortgage [Member] | Permanent mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 1,036,793,000 | 1,095,097,000
Nonaccrual | 20,165,000 | 23,951,000
Total | 1,066,460,000 | 1,122,610,000
Residential mortgage [Member] | Permanent mortgages guaranteed by US government agencies [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 47,207,000 | 37,459,000
Nonaccrual | 6,332,000 | 7,132,000
Total | 191,764,000 | 190,866,000
Residential mortgage [Member] | Home equity [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 845,616,000 | 904,572,000
Nonaccrual | 10,807,000 | 10,472,000
Total | 859,079,000 | 916,557,000
Personal [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Current | 1,116,888,000 | 1,024,298,000
Nonaccrual | 271,000 | 230,000
Total | 1,117,382,000 | 1,025,806,000
30 to 59 Days [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 51,586,000 | 53,350,000
30 to 59 Days [Member] | Commercial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 12,955,000 | 7,675,000
30 to 59 Days [Member] | Commercial [Member] | Energy [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
30 to 59 Days [Member] | Commercial [Member] | Services [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 7,305,000 | 6,009,000
30 to 59 Days [Member] | Commercial [Member] | Wholesale/retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 2,910,000 | 515,000
30 to 59 Days [Member] | Commercial [Member] | Manufacturing [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 2,309,000 | 392,000
30 to 59 Days [Member] | Commercial [Member] | Healthcare [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 94,000 | 241,000
30 to 59 Days [Member] | Commercial [Member] | Public finance [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
30 to 59 Days [Member] | Commercial [Member] | Other commercial and industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 337,000 | 518,000
30 to 59 Days [Member] | Commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 6,740,000 | 16,529,000
30 to 59 Days [Member] | Commercial real estate [Member] | Residential construction and land development [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 249,000
30 to 59 Days [Member] | Commercial real estate [Member] | Retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 14,379,000
30 to 59 Days [Member] | Commercial real estate [Member] | Office [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
30 to 59 Days [Member] | Commercial real estate [Member] | Multifamily [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 6,405,000 | 281,000
30 to 59 Days [Member] | Commercial real estate [Member] | Industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 1,208,000
30 to 59 Days [Member] | Commercial real estate [Member] | Other commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 335,000 | 412,000
30 to 59 Days [Member] | Residential mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 31,791,000 | 28,667,000
30 to 59 Days [Member] | Residential mortgage [Member] | Permanent mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 6,097,000 | 3,196,000
30 to 59 Days [Member] | Residential mortgage [Member] | Permanent mortgages guaranteed by US government agencies [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 23,412,000 | 24,369,000
30 to 59 Days [Member] | Residential mortgage [Member] | Home equity [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 2,282,000 | 1,102,000
30 to 59 Days [Member] | Personal [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 100,000 | 479,000
60 to 89 Days [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 27,801,000 | 24,245,000
60 to 89 Days [Member] | Commercial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 2,146,000 | 6,106,000
60 to 89 Days [Member] | Commercial [Member] | Energy [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
60 to 89 Days [Member] | Commercial [Member] | Services [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 2,096,000 | 6,038,000
60 to 89 Days [Member] | Commercial [Member] | Wholesale/retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 37,000
60 to 89 Days [Member] | Commercial [Member] | Manufacturing [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 6,000
60 to 89 Days [Member] | Commercial [Member] | Healthcare [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 2,000 | 0
60 to 89 Days [Member] | Commercial [Member] | Public finance [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
60 to 89 Days [Member] | Commercial [Member] | Other commercial and industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 48,000 | 25,000
60 to 89 Days [Member] | Commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 106,000 | 280,000
60 to 89 Days [Member] | Commercial real estate [Member] | Residential construction and land development [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 280,000
60 to 89 Days [Member] | Commercial real estate [Member] | Retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
60 to 89 Days [Member] | Commercial real estate [Member] | Office [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
60 to 89 Days [Member] | Commercial real estate [Member] | Multifamily [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
60 to 89 Days [Member] | Commercial real estate [Member] | Industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
60 to 89 Days [Member] | Commercial real estate [Member] | Other commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 106,000 | 0
60 to 89 Days [Member] | Residential mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 25,455,000 | 17,063,000
60 to 89 Days [Member] | Residential mortgage [Member] | Permanent mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 3,405,000 | 366,000
60 to 89 Days [Member] | Residential mortgage [Member] | Permanent mortgages guaranteed by US government agencies [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 21,676,000 | 16,345,000
60 to 89 Days [Member] | Residential mortgage [Member] | Home equity [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 374,000 | 352,000
60 to 89 Days [Member] | Personal [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 94,000 | 796,000
90 Days or More [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 94,678,000 | 106,899,000
90 Days or More [Member] | Commercial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 791,000 | 562,000
90 Days or More [Member] | Commercial [Member] | Energy [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial [Member] | Services [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 735,000 | 0
90 Days or More [Member] | Commercial [Member] | Wholesale/retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial [Member] | Manufacturing [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial [Member] | Healthcare [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 56,000 | 554,000
90 Days or More [Member] | Commercial [Member] | Public finance [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial [Member] | Other commercial and industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 8,000
90 Days or More [Member] | Commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 721,000 | 714,000
90 Days or More [Member] | Commercial real estate [Member] | Residential construction and land development [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 64,000 | 0
90 Days or More [Member] | Commercial real estate [Member] | Retail [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial real estate [Member] | Office [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial real estate [Member] | Multifamily [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial real estate [Member] | Industrial [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Commercial real estate [Member] | Other commercial real estate [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 657,000 | 714,000
90 Days or More [Member] | Residential mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 93,137,000 | 105,620,000
90 Days or More [Member] | Residential mortgage [Member] | Permanent mortgage [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 0
90 Days or More [Member] | Residential mortgage [Member] | Permanent mortgages guaranteed by US government agencies [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 93,137,000 | 105,561,000
90 Days or More [Member] | Residential mortgage [Member] | Home equity [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | 0 | 59,000
90 Days or More [Member] | Personal [Member] |  |
Financing receivable, recorded investment, aging [Abstract] |  |
Past Due | $ 29,000 | $ 3,000

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