Loans | Loans The period end loan composition was as follows. September 30, December 31, ($ in Thousands) Commercial and industrial $ 6,721,557 $ 6,190,683 Commercial real estate — owner occupied 892,678 918,212 Commercial and business lending 7,614,235 7,108,895 Commercial real estate — investor 3,530,370 3,234,266 Real estate construction 1,314,431 1,162,145 Commercial real estate lending 4,844,801 4,396,411 Total commercial 12,459,036 11,505,306 Residential mortgage 6,034,166 5,783,267 Home equity 951,594 1,005,802 Other consumer 399,209 419,968 Total consumer 7,384,969 7,209,037 Total loans $ 19,844,005 $ 18,714,343 The following table presents commercial and consumer loans by credit quality indicator at September 30, 2016 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 5,983,940 $ 180,425 $ 351,290 $ 205,902 $ 6,721,557 Commercial real estate - owner occupied 791,951 46,345 47,387 6,995 892,678 Commercial and business lending 6,775,891 226,770 398,677 212,897 7,614,235 Commercial real estate - investor 3,480,535 5,042 36,765 8,028 3,530,370 Real estate construction 1,303,013 8,625 1,929 864 1,314,431 Commercial real estate lending 4,783,548 13,667 38,694 8,892 4,844,801 Total commercial 11,559,439 240,437 437,371 221,789 12,459,036 Residential mortgage 5,973,633 3,832 3,226 53,475 6,034,166 Home equity 936,443 726 78 14,347 951,594 Other consumer 398,481 428 — 300 399,209 Total consumer 7,308,557 4,986 3,304 68,122 7,384,969 Total loans $ 18,867,996 $ 245,423 $ 440,675 $ 289,911 $ 19,844,005 The following table presents commercial and consumer loans by credit quality indicator at December 31, 2015 . Pass Special Mention Potential Problem Nonaccrual Total ($ in Thousands) Commercial and industrial $ 5,522,809 $ 341,169 $ 233,130 $ 93,575 $ 6,190,683 Commercial real estate - owner occupied 835,572 38,885 35,706 8,049 918,212 Commercial and business lending 6,358,381 380,054 268,836 101,624 7,108,895 Commercial real estate - investor 3,153,703 45,976 25,944 8,643 3,234,266 Real estate construction 1,157,034 252 3,919 940 1,162,145 Commercial real estate lending 4,310,737 46,228 29,863 9,583 4,396,411 Total commercial 10,669,118 426,282 298,699 111,207 11,505,306 Residential mortgage 5,727,437 1,552 2,796 51,482 5,783,267 Home equity 988,574 1,762 222 15,244 1,005,802 Other consumer 419,087 556 — 325 419,968 Total consumer 7,135,098 3,870 3,018 67,051 7,209,037 Total loans $ 17,804,216 $ 430,152 $ 301,717 $ 178,258 $ 18,714,343 Factors that are important to managing overall credit quality are sound loan underwriting and administration, systematic monitoring of existing loans and commitments, effective loan review on an ongoing basis, early identification of potential problems, and appropriate allowance for loan losses, allowance for unfunded commitments, nonaccrual, and charge off policies. For commercial loans, management has determined the pass credit quality indicator to include credits that exhibit acceptable financial statements, cash flow, and leverage. If any risk exists, it is mitigated by the loan structure, collateral, monitoring, or control. For consumer loans, performing loans include credits that are performing in accordance with the original contractual terms. Loans are considered past due if the required principal and interest payments have not been received as of the date such payments were due. Special mention credits have potential weaknesses that deserve management’s attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the credit. Potential problem loans are considered inadequately protected by the current net worth and paying capacity of the obligor or the collateral pledged. These loans generally have a well-defined weakness, or weaknesses, that may jeopardize liquidation of the debt and are characterized by the distinct possibility that the Corporation will sustain some loss if the deficiencies are not corrected. Lastly, management considers a loan to be impaired when it is probable that the Corporation will be unable to collect all amounts due according to the original contractual terms of the note agreement, including both principal and interest. Management has determined that commercial and consumer loan relationships that have nonaccrual status or have had their terms restructured in a troubled debt restructuring meet this impaired loan definition. Commercial loans classified as special mention, potential problem, and nonaccrual loans are reviewed at a minimum on a quarterly basis, while pass rated credits are reviewed on an annual basis or more frequently if the loan renewal is less than one year or if otherwise warranted. The following table presents loans by past due status at September 30, 2016 . Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due (a) Nonaccrual (b) Total ($ in Thousands) Commercial and industrial $ 6,514,451 $ 576 $ 374 $ 254 $ 205,902 $ 6,721,557 Commercial real estate - owner occupied 884,814 754 115 — 6,995 892,678 Commercial and business lending 7,399,265 1,330 489 254 212,897 7,614,235 Commercial real estate - investor 3,521,712 17 613 — 8,028 3,530,370 Real estate construction 1,313,165 337 65 — 864 1,314,431 Commercial real estate lending 4,834,877 354 678 — 8,892 4,844,801 Total commercial 12,234,142 1,684 1,167 254 221,789 12,459,036 Residential mortgage 5,973,994 6,407 290 — 53,475 6,034,166 Home equity 931,774 4,627 846 — 14,347 951,594 Other consumer 395,606 1,499 547 1,257 300 399,209 Total consumer 7,301,374 12,533 1,683 1,257 68,122 7,384,969 Total loans $ 19,535,516 $ 14,217 $ 2,850 $ 1,511 $ 289,911 $ 19,844,005 (a) The recorded investment in loans past due 90 days or more and still accruing totaled $2 million at September 30, 2016 (the same as the reported balances for the accruing loans noted above). (b) Of the total nonaccrual loans, $215 million or 74% were current with respect to payment at September 30, 2016 . The following table presents loans by past due status at December 31, 2015 . Current 30-59 Days Past Due 60-89 Days Past Due 90 Days or More Past Due (a) Nonaccrual (b) Total ($ in Thousands) Commercial and industrial $ 6,095,848 $ 602 $ 409 $ 249 $ 93,575 $ 6,190,683 Commercial real estate - owner occupied 903,021 7,142 — — 8,049 918,212 Commercial and business lending 6,998,869 7,744 409 249 101,624 7,108,895 Commercial real estate - investor 3,225,332 291 — — 8,643 3,234,266 Real estate construction 1,160,909 270 26 — 940 1,162,145 Commercial real estate lending 4,386,241 561 26 — 9,583 4,396,411 Total commercial 11,385,110 8,305 435 249 111,207 11,505,306 Residential mortgage 5,726,855 4,491 439 — 51,482 5,783,267 Home equity 982,639 6,190 1,729 — 15,244 1,005,802 Other consumer 416,374 1,195 675 1,399 325 419,968 Total consumer 7,125,868 11,876 2,843 1,399 67,051 7,209,037 Total loans $ 18,510,978 $ 20,181 $ 3,278 $ 1,648 $ 178,258 $ 18,714,343 (a) The recorded investment in loans past due 90 days or more and still accruing totaled $2 million at December 31, 2015 (the same as the reported balances for the accruing loans noted above). (b) Of the total nonaccrual loans, $124 million or 69% were current with respect to payment at December 31, 2015 . The following table presents impaired loans at September 30, 2016 . Recorded Unpaid Related Average Interest ($ in Thousands) Loans with a related allowance Commercial and industrial $ 61,219 $ 65,586 $ 9,293 $ 61,337 $ 1,228 Commercial real estate — owner occupied 8,721 10,641 319 9,133 262 Commercial and business lending 69,940 76,227 9,612 70,470 1,490 Commercial real estate — investor 17,154 17,601 629 21,450 1,405 Real estate construction 1,229 1,626 449 1,301 49 Commercial real estate lending 18,383 19,227 1,078 22,751 1,454 Total commercial 88,323 95,454 10,690 93,221 2,944 Residential mortgage 65,381 70,568 12,087 66,845 1,734 Home equity 21,382 23,277 10,162 22,654 862 Other consumer 1,226 1,288 211 1,268 22 Total consumer 87,989 95,133 22,460 90,767 2,618 Total loans $ 176,312 $ 190,587 $ 33,150 $ 183,988 $ 5,562 Loans with no related allowance Commercial and industrial $ 174,931 $ 221,213 $ — $ 179,696 $ 1,227 Commercial real estate — owner occupied 5,719 6,472 — 5,906 — Commercial and business lending 180,650 227,685 — 185,602 1,227 Commercial real estate — investor 6,226 6,501 — 7,393 — Real estate construction — — — — — Commercial real estate lending 6,226 6,501 — 7,393 — Total commercial 186,876 234,186 — 192,995 1,227 Residential mortgage 6,143 6,289 — 6,206 133 Home equity 650 650 — 651 23 Other consumer — — — — — Total consumer 6,793 6,939 — 6,857 156 Total loans $ 193,669 $ 241,125 $ — $ 199,852 $ 1,383 Total Commercial and industrial $ 236,150 $ 286,799 $ 9,293 $ 241,033 $ 2,455 Commercial real estate — owner occupied 14,440 17,113 319 15,039 262 Commercial and business lending 250,590 303,912 9,612 256,072 2,717 Commercial real estate — investor 23,380 24,102 629 28,843 1,405 Real estate construction 1,229 1,626 449 1,301 49 Commercial real estate lending 24,609 25,728 1,078 30,144 1,454 Total commercial 275,199 329,640 10,690 286,216 4,171 Residential mortgage 71,524 76,857 12,087 73,051 1,867 Home equity 22,032 23,927 10,162 23,305 885 Other consumer 1,226 1,288 211 1,268 22 Total consumer 94,782 102,072 22,460 97,624 2,774 Total impaired loans (a) $ 369,981 $ 431,712 $ 33,150 $ 383,840 $ 6,945 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 78% of the unpaid principal balance at September 30, 2016 . The following table presents impaired loans at December 31, 2015 . Recorded Investment Unpaid Principal Balance Related Allowance Average Recorded Investment Interest Income Recognized ($ in Thousands) Loans with a related allowance Commercial and industrial $ 57,785 $ 59,409 $ 8,162 $ 46,833 $ 855 Commercial real estate — owner occupied 9,705 9,804 448 10,087 412 Commercial and business lending 67,490 69,213 8,610 56,920 1,267 Commercial real estate — investor 27,822 29,444 1,831 28,278 1,914 Real estate construction 1,450 2,154 453 1,667 66 Commercial real estate lending 29,272 31,598 2,284 29,945 1,980 Total commercial 96,762 100,811 10,894 86,865 3,247 Residential mortgage 66,590 71,084 12,462 68,183 2,374 Home equity 21,769 23,989 10,118 22,624 1,147 Other consumer 1,154 1,225 195 1,199 30 Total consumer 89,513 96,298 22,775 92,006 3,551 Total loans $ 186,275 $ 197,109 $ 33,669 $ 178,871 $ 6,798 Loans with no related allowance Commercial and industrial $ 65,083 $ 72,259 $ — $ 79,573 $ 1,657 Commercial real estate — owner occupied 6,221 6,648 — 6,534 15 Commercial and business lending 71,304 78,907 — 86,107 1,672 Commercial real estate — investor 2,736 2,840 — 2,763 90 Real estate construction — — — — — Commercial real estate lending 2,736 2,840 — 2,763 90 Total commercial 74,040 81,747 — 88,870 1,762 Residential mortgage 4,762 5,033 — 4,726 126 Home equity 544 544 — 544 30 Other consumer — — — — — Total consumer 5,306 5,577 — 5,270 156 Total loans $ 79,346 $ 87,324 $ — $ 94,140 $ 1,918 Total Commercial and industrial $ 122,868 $ 131,668 $ 8,162 $ 126,406 $ 2,512 Commercial real estate — owner occupied 15,926 16,452 448 16,621 427 Commercial and business lending 138,794 148,120 8,610 143,027 2,939 Commercial real estate — investor 30,558 32,284 1,831 31,041 2,004 Real estate construction 1,450 2,154 453 1,667 66 Commercial real estate lending 32,008 34,438 2,284 32,708 2,070 Total commercial 170,802 182,558 10,894 175,735 5,009 Residential mortgage 71,352 76,117 12,462 72,909 2,500 Home equity 22,313 24,533 10,118 23,168 1,177 Other consumer 1,154 1,225 195 1,199 30 Total consumer 94,819 101,875 22,775 97,276 3,707 Total impaired loans (a) $ 265,621 $ 284,433 $ 33,669 $ 273,011 $ 8,716 (a) The net recorded investment (defined as recorded investment, net of the related allowance) of the impaired loans represented 82% of the unpaid principal balance at December 31, 2015 . Troubled Debt Restructurings (“Restructured Loans”): Loans are considered restructured loans if concessions have been granted to borrowers that are experiencing financial difficulty. See Note 1 “Summary of Significant Accounting Policies," in the Corporation’s 2015 Annual Report on Form 10-K for the Corporation's accounting policy for troubled debt restructurings. The Corporation had a recorded investment of $9 million in loans modified in troubled debt restructurings for the nine months ended September 30, 2016 , of which approximately $4 million was in accrual status and $5 million was in nonaccrual pending a sustained period of repayment. The following table presents nonaccrual and performing restructured loans by loan portfolio. September 30, 2016 December 31, 2015 Performing Restructured Loans Nonaccrual Restructured Loans (a) Performing Restructured Loans Nonaccrual Restructured Loans (a) ($ in Thousands) Commercial and industrial $ 30,248 $ 2,398 $ 29,293 $ 1,714 Commercial real estate — owner occupied 7,445 2,275 7,877 2,703 Commercial real estate — investor 15,352 941 21,915 3,936 Real estate construction 365 154 510 177 Residential mortgage 18,049 22,743 19,870 24,592 Home equity 7,685 3,209 7,069 4,522 Other consumer 926 38 829 40 Total restructured loans $ 80,070 $ 31,758 $ 87,363 $ 37,684 (a) Nonaccrual restructured loans have been included within nonaccrual loans. The following table provides the number of loans modified in a troubled debt restructuring by loan portfolio during the nine months ended September 30, 2016 and 2015 , and the recorded investment and unpaid principal balance as of September 30, 2016 and 2015 . Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) Number of Loans Recorded Investment (a) Unpaid Principal Balance (b) ($ in Thousands) Commercial and industrial 10 $ 2,455 $ 2,517 10 $ 2,410 $ 3,033 Commercial real estate — owner occupied 1 117 124 4 2,847 3,007 Commercial real estate — investor — — — 3 2,949 2,998 Real estate construction 1 66 91 1 5 5 Residential mortgage 56 4,676 4,922 77 7,393 7,586 Home equity 47 1,709 1,793 61 2,109 2,220 Other consumer 1 15 16 — — — Total 116 $ 9,038 $ 9,463 156 $ 17,713 $ 18,849 (a) Represents post-modification outstanding recorded investment. (b) Represents pre-modification outstanding recorded investment. Restructured loan modifications may include payment schedule modifications, interest rate concessions, maturity date extensions, modification of note structure (A/B Note), non-reaffirmed Chapter 7 bankruptcies, principal reduction, or some combination of these concessions. During the nine months ended September 30, 2016 , restructured loan modifications of commercial and industrial, commercial real estate, and real estate construction loans primarily included maturity date extensions, interest rate concessions, payment schedule modifications, or a combination of these concessions. Restructured loan modifications of home equity and residential mortgage loans primarily included maturity date extensions, interest rate concessions, non-reaffirmed Chapter 7 bankruptcies, or a combination of these concessions for the nine months ended September 30, 2016 . The following table provides the number of loans modified in a troubled debt restructuring during the previous twelve months which subsequently defaulted during the nine months ended September 30, 2016 and 2015 , as well as the recorded investment in these restructured loans as of September 30, 2016 and 2015 . Nine Months Ended September 30, 2016 Nine Months Ended September 30, 2015 Number of Loans Recorded Investment Number of Loans Recorded Investment ($ in Thousands) Commercial and industrial — $ — 1 $ 153 Commercial real estate — owner occupied — — 1 297 Residential mortgage 36 3,310 45 4,176 Home equity 12 182 21 627 Other consumer 1 15 — — Total 49 $ 3,507 68 $ 5,253 All loans modified in a troubled debt restructuring are evaluated for impairment. The nature and extent of the impairment of restructured loans, including those which have experienced a subsequent payment default, is considered in the determination of an appropriate level of the allowance for loan losses. A summary of the changes in the allowance for loan losses by portfolio segment for the nine months ended September 30, 2016 , was as follows. $ in Thousands Commercial and industrial Commercial real estate - owner occupied Commercial real estate - investor Real estate construction Residential mortgage Home equity Other consumer Total December 31, 2015 $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Charge offs (63,368 ) (265 ) (1,495 ) (380 ) (3,035 ) (3,434 ) (2,853 ) (74,830 ) Recoveries 13,461 48 1,610 111 506 2,730 640 19,106 Net charge offs (49,907 ) (217 ) 115 (269 ) (2,529 ) (704 ) (2,213 ) (55,724 ) Provision for loan losses 57,051 (4,106 ) (2,366 ) (1,873 ) 1,121 (897 ) 2,070 51,000 September 30, 2016 $ 137,103 $ 14,357 $ 40,767 $ 23,124 $ 26,853 $ 21,954 $ 5,382 $ 269,540 Allowance for loan losses: Individually evaluated for impairment $ 8,570 $ — $ 79 $ — $ 976 $ — $ — $ 9,625 Collectively evaluated for impairment 128,533 14,357 40,688 23,124 25,877 21,954 5,382 259,915 Total allowance for loan losses $ 137,103 $ 14,357 $ 40,767 $ 23,124 $ 26,853 $ 21,954 $ 5,382 $ 269,540 Loans: Individually evaluated for impairment $ 203,834 $ 5,719 $ 7,023 $ — $ 9,389 $ 650 $ — $ 226,615 Collectively evaluated for impairment 6,517,723 886,959 3,523,347 1,314,431 6,024,777 950,944 399,209 19,617,390 Total loans $ 6,721,557 $ 892,678 $ 3,530,370 $ 1,314,431 $ 6,034,166 $ 951,594 $ 399,209 $ 19,844,005 The allowance for credit losses is comprised of the allowance for loan losses and the allowance for unfunded commitments. The level of the allowance for loan losses represents management’s estimate of an amount appropriate to provide for probable credit losses in the loan portfolio at the balance sheet date. The allowance for unfunded commitments is maintained at a level believed by management to be sufficient to absorb estimated probable losses related to unfunded credit facilities (including unfunded loan commitments and letters of credit) and is included in accrued expenses and other liabilities on the consolidated balance sheets. See Note 12 for additional information on the allowance for unfunded commitments. For comparison purposes, a summary of the changes in the allowance for loan losses by portfolio segment for the year ended December 31, 2015 , was as follows. $ in Thousands Commercial and industrial Commercial real estate - owner occupied Commercial real estate - investor Real estate construction Residential mortgage Home equity Other consumer Total December 31, 2014 $ 117,635 $ 16,510 $ 46,333 $ 20,999 $ 31,926 $ 26,464 $ 6,435 $ 266,302 Charge offs (27,687 ) (2,645 ) (4,645 ) (750 ) (5,636 ) (7,048 ) (3,869 ) (52,280 ) Recoveries 9,821 921 4,157 2,268 1,077 3,233 765 22,242 Net charge offs (17,866 ) (1,724 ) (488 ) 1,518 (4,559 ) (3,815 ) (3,104 ) (30,038 ) Provision for loan losses 30,190 3,894 (2,827 ) 2,749 894 906 2,194 38,000 December 31, 2015 $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Allowance for loan losses: Individually evaluated for impairment $ 7,522 $ — $ 229 $ — $ 166 $ 46 $ — $ 7,963 Collectively evaluated for impairment 122,437 18,680 42,789 25,266 28,095 23,509 5,525 266,301 Total allowance for loan losses $ 129,959 $ 18,680 $ 43,018 $ 25,266 $ 28,261 $ 23,555 $ 5,525 $ 274,264 Loans: Individually evaluated for impairment $ 91,569 $ 6,221 $ 5,460 $ — $ 6,956 $ 1,281 $ — $ 111,487 Collectively evaluated for impairment 6,099,114 911,991 3,228,806 1,162,145 5,776,311 1,004,521 419,968 18,602,856 Total loans $ 6,190,683 $ 918,212 $ 3,234,266 $ 1,162,145 $ 5,783,267 $ 1,005,802 $ 419,968 $ 18,714,343 A summary of the changes in the allowance for unfunded commitments was as follows. Nine Months Ended September 30, 2016 Year Ended December 31, 2015 ($ in Thousands) Allowance for Unfunded Commitments: Balance at beginning of period $ 24,400 $ 24,900 Provision for unfunded commitments 4,000 (500 ) Balance at end of period $ 28,400 $ 24,400 |