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Loans and Allowance for Credit Losses, Impaired Loans (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | $ 392,990 |  | $ 460,466 |  | $ 392,990 |  | $ 460,466 |  | $ 438,459 |
Impaired loans, recorded investment, total | 325,920 |  | 404,115 |  | 325,920 |  | 404,115 |  | 376,201 |
Impaired loans, recorded investment with no related allowance | 287,442 |  | 314,610 |  | 287,442 |  | 314,610 |  | 324,867 |
Impaired loans, recorded investment with related allowance | 38,478 |  | 89,505 |  | 38,478 |  | 89,505 |  | 51,334 |
Impaired loans, related allowance | 13,797 |  | 13,284 |  | 13,797 |  | 13,284 |  | 8,831 |
Impaired loans, average recorded investment | 326,300 |  | 415,027 |  | 340,591 |  | 417,476 |  |  |
Impaired loans, interest income recognized | 1,875 |  | 2,199 |  | 5,926 |  | 6,721 |  |  |
Commercial [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 156,620 |  | 218,386 |  | 156,620 |  | 218,386 |  | 184,604 |
Impaired loans, recorded investment, total | 109,490 |  | 176,900 |  | 109,490 |  | 176,900 |  | 137,303 |
Impaired loans, recorded investment with no related allowance | 71,012 |  | 87,395 |  | 71,012 |  | 87,395 |  | 85,969 |
Impaired loans, recorded investment with related allowance | 38,478 |  | 89,505 |  | 38,478 |  | 89,505 |  | 51,334 |
Impaired loans, related allowance | 13,797 |  | 13,284 |  | 13,797 |  | 13,284 |  | 8,831 |
Impaired loans, average recorded investment | 115,234 |  | 187,029 |  | 123,396 |  | 177,927 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial [Member] | Energy [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 73,600 |  | 133,643 |  | 73,600 |  | 133,643 |  | 111,011 |
Impaired loans, recorded investment, total | 54,033 |  | 110,683 |  | 54,033 |  | 110,683 |  | 92,284 |
Impaired loans, recorded investment with no related allowance | 28,180 |  | 45,169 |  | 28,180 |  | 45,169 |  | 40,968 |
Impaired loans, recorded investment with related allowance | 25,853 |  | 65,514 |  | 25,853 |  | 65,514 |  | 51,316 |
Impaired loans, related allowance | 5,305 |  | 4,944 |  | 5,305 |  | 4,944 |  | 8,814 |
Impaired loans, average recorded investment | 59,815 |  | 117,338 |  | 73,159 |  | 121,591 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial [Member] | Services [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 6,959 |  | 3,838 |  | 6,959 |  | 3,838 |  | 5,324 |
Impaired loans, recorded investment, total | 4,097 |  | 1,174 |  | 4,097 |  | 1,174 |  | 2,620 |
Impaired loans, recorded investment with no related allowance | 4,021 |  | 1,174 |  | 4,021 |  | 1,174 |  | 2,620 |
Impaired loans, recorded investment with related allowance | 76 |  | 0 |  | 76 |  | 0 |  | 0 |
Impaired loans, related allowance | 76 |  | 0 |  | 76 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 4,237 |  | 4,464 |  | 3,358 |  | 4,674 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial [Member] | Wholesale/retail [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 14,281 |  | 8,418 |  | 14,281 |  | 8,418 |  | 9,099 |
Impaired loans, recorded investment, total | 9,249 |  | 1,893 |  | 9,249 |  | 1,893 |  | 2,574 |
Impaired loans, recorded investment with no related allowance | 2,227 |  | 1,893 |  | 2,227 |  | 1,893 |  | 2,574 |
Impaired loans, recorded investment with related allowance | 7,022 |  | 0 |  | 7,022 |  | 0 |  | 0 |
Impaired loans, related allowance | 4,102 |  | 0 |  | 4,102 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 11,672 |  | 6,256 |  | 5,911 |  | 6,650 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial [Member] | Manufacturing [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 9,212 | [1] | 9,674 |  | 9,212 | [1] | 9,674 |  | 6,073 |
Impaired loans, recorded investment, total | 9,202 | [1] | 9,059 |  | 9,202 | [1] | 9,059 |  | 5,962 |
Impaired loans, recorded investment with no related allowance | 6,217 | [1] | 9,059 |  | 6,217 | [1] | 9,059 |  | 5,962 |
Impaired loans, recorded investment with related allowance | 2,985 | [1] | 0 |  | 2,985 | [1] | 0 |  | 0 |
Impaired loans, related allowance | 2,985 | [1] | 0 |  | 2,985 | [1] | 0 |  | 0 |
Impaired loans, average recorded investment | 6,096 | [1] | 9,357 |  | 7,582 | [1] | 6,995 |  |  |
Impaired loans, interest income recognized | 0 | [1] | 0 |  | 0 | [1] | 0 |  |  |
Impaired loans, unpaid principal balance to affiliates | 6,200 |  |  |  | 6,200 |  |  |  |  |
Commercial [Member] | Healthcare [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 25,923 |  | 24,591 |  | 25,923 |  | 24,591 |  | 25,140 |
Impaired loans, recorded investment, total | 15,704 |  | 24,446 |  | 15,704 |  | 24,446 |  | 14,765 |
Impaired loans, recorded investment with no related allowance | 13,162 |  | 474 |  | 13,162 |  | 474 |  | 14,765 |
Impaired loans, recorded investment with related allowance | 2,542 |  | 23,972 |  | 2,542 |  | 23,972 |  | 0 |
Impaired loans, related allowance | 1,329 |  | 8,323 |  | 1,329 |  | 8,323 |  | 0 |
Impaired loans, average recorded investment | 15,915 |  | 24,476 |  | 15,235 |  | 12,635 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial [Member] | Other commercial and industrial [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 26,645 |  | 38,222 |  | 26,645 |  | 38,222 |  | 27,957 |
Impaired loans, recorded investment, total | 17,205 |  | 29,645 |  | 17,205 |  | 29,645 |  | 19,098 |
Impaired loans, recorded investment with no related allowance | 17,205 |  | 29,626 |  | 17,205 |  | 29,626 |  | 19,080 |
Impaired loans, recorded investment with related allowance | 0 |  | 19 |  | 0 |  | 19 |  | 18 |
Impaired loans, related allowance | 0 |  | 17 |  | 0 |  | 17 |  | 17 |
Impaired loans, average recorded investment | 17,499 |  | 25,138 |  | 18,151 |  | 25,382 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 9,611 |  | 5,003 |  | 9,611 |  | 5,003 |  | 4,751 |
Impaired loans, recorded investment, total | 1,316 |  | 2,975 |  | 1,316 |  | 2,975 |  | 2,855 |
Impaired loans, recorded investment with no related allowance | 1,316 |  | 2,975 |  | 1,316 |  | 2,975 |  | 2,855 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 1,656 |  | 3,375 |  | 2,085 |  | 4,250 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Residential construction and land development [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 1,306 |  | 3,532 |  | 1,306 |  | 3,532 |  | 3,285 |
Impaired loans, recorded investment, total | 350 |  | 1,924 |  | 350 |  | 1,924 |  | 1,832 |
Impaired loans, recorded investment with no related allowance | 350 |  | 1,924 |  | 350 |  | 1,924 |  | 1,832 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 350 |  | 1,988 |  | 1,091 |  | 2,679 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Retail [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 7,951 |  | 513 |  | 7,951 |  | 513 |  | 509 |
Impaired loans, recorded investment, total | 777 |  | 289 |  | 777 |  | 289 |  | 276 |
Impaired loans, recorded investment with no related allowance | 777 |  | 289 |  | 777 |  | 289 |  | 276 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 923 |  | 295 |  | 527 |  | 308 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Office [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 0 |  | 287 |  | 0 |  | 287 |  | 287 |
Impaired loans, recorded investment, total | 0 |  | 275 |  | 0 |  | 275 |  | 275 |
Impaired loans, recorded investment with no related allowance | 0 |  | 275 |  | 0 |  | 275 |  | 275 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 137 |  | 335 |  | 137 |  | 351 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Multifamily [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment, total | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment with no related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 0 |  | 5 |  | 0 |  | 19 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Industrial [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment, total | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment with no related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 0 |  | 0 |  | 0 |  | 38 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Other commercial real estate [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 354 |  | 671 |  | 354 |  | 671 |  | 670 |
Impaired loans, recorded investment, total | 189 |  | 487 |  | 189 |  | 487 |  | 472 |
Impaired loans, recorded investment with no related allowance | 189 |  | 487 |  | 189 |  | 487 |  | 472 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 246 |  | 752 |  | 330 |  | 855 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Residential mortgage [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 226,439 |  | 236,787 |  | 226,439 |  | 236,787 |  | 248,797 |
Impaired loans, recorded investment, total | 214,845 |  | 223,985 |  | 214,845 |  | 223,985 |  | 235,774 |
Impaired loans, recorded investment with no related allowance | 214,845 |  | 223,985 |  | 214,845 |  | 223,985 |  | 235,774 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 209,105 |  | 224,360 |  | 214,841 |  | 235,026 |  |  |
Impaired loans, interest income recognized | 1,875 |  | 2,199 |  | 5,926 |  | 6,721 |  |  |
Residential mortgage [Member] | Permanent mortgage [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 27,603 |  | 29,861 |  | 27,603 |  | 29,861 |  | 30,435 |
Impaired loans, recorded investment, total | 22,855 |  | 24,623 |  | 22,855 |  | 24,623 |  | 25,193 |
Impaired loans, recorded investment with no related allowance | 22,855 |  | 24,623 |  | 22,855 |  | 24,623 |  | 25,193 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 22,980 |  | 24,019 |  | 24,024 |  | 23,739 |  |  |
Impaired loans, interest income recognized | 318 |  | 315 |  | 947 |  | 912 |  |  |
Residential mortgage [Member] | Permanent mortgages guaranteed by US government agencies [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 185,788 | [2] | 193,594 | [3] | 185,788 | [2] | 193,594 | [3] | 203,814 | [4]
Impaired loans, recorded investment, total | 180,718 | [2] | 187,370 | [3] | 180,718 | [2] | 187,370 | [3] | 197,506 | [4]
Impaired loans, recorded investment with no related allowance | 180,718 | [2] | 187,370 | [3] | 180,718 | [2] | 187,370 | [3] | 197,506 | [4]
Impaired loans, recorded investment with related allowance | 0 | [2] | 0 | [3] | 0 | [2] | 0 | [3] | 0 | [4]
Impaired loans, related allowance | 0 | [2] | 0 | [3] | 0 | [2] | 0 | [3] | 0 | [4]
Impaired loans, average recorded investment | 174,653 | [2] | 188,461 | [3] | 178,643 | [2] | 199,532 | [3] |  |
Impaired loans, interest income recognized | 1,557 | [2] | 1,884 | [3] | 4,979 | [2] | 5,809 | [3] |  |
Residential mortgage [Member] | Home equity [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 13,048 |  | 13,332 |  | 13,048 |  | 13,332 |  | 14,548 |
Impaired loans, recorded investment, total | 11,272 |  | 11,992 |  | 11,272 |  | 11,992 |  | 13,075 |
Impaired loans, recorded investment with no related allowance | 11,272 |  | 11,992 |  | 11,272 |  | 11,992 |  | 13,075 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment | 11,472 |  | 11,880 |  | 12,174 |  | 11,755 |  |  |
Impaired loans, interest income recognized | 0 |  | 0 |  | 0 |  | 0 |  |  |
Personal [Member] |  |  |  |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |  |  |  |
Impaired loans, unpaid principal balance | 320 |  | 290 |  | 320 |  | 290 |  | 307 |
Impaired loans, recorded investment, total | 269 |  | 255 |  | 269 |  | 255 |  | 269 |
Impaired loans, recorded investment with no related allowance | 269 |  | 255 |  | 269 |  | 255 |  | 269 |
Impaired loans, recorded investment with related allowance | 0 |  | 0 |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance | 0 |  | 0 |  | 0 |  | 0 |  | $ 0 |
Impaired loans, average recorded investment | 305 |  | 263 |  | 269 |  | 273 |  |  |
Impaired loans, interest income recognized | $ 0 |  | $ 0 |  | $ 0 |  | $ 0 |  |  |
[1] | Impaired manufacturing sector loans included $6.2 million of loans from an affiliated entity, with no allowance as the fair value of the collateral exceeded the outstanding principal balance at September 30, 2018.
[2] | All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2018, $7.8 million of these loans were nonaccruing and $173 million were accruing based on the guarantee by U.S. government agencies.
[3] | All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2017, $8.9 million of these loans were nonaccruing and $178 million were accruing based on the guarantee by U.S. government agencies.
[4] | All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2017, $9.2 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

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