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Fair Value Measurements (Tables) | 6 Months Ended
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Jun. 30, 2018
Fair Value Disclosures [Abstract] |
Fair Value Assets And Liabilities Measured On A Recurring Basis [Table Text Block] | The fair value of financial assets and liabilities measured on a recurring basis was as follows as of June 30, 2018 (in thousands):
|  | Total |  | Quoted Prices in Active Markets for Identical Instruments (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
Assets: |  |  |  |  |  |  |  |
Trading securities: |  |  |  |  |  |  |  |
U.S. government agency debentures |  | $ | 28,750 |  |  | $ | — |  |  | $ | 28,750 |  |  | $ | — |
U.S. government agency residential mortgage-backed securities |  | 1,605,001 |  |  | — |  |  | 1,605,001 |  |  | — |
Municipal and other tax-exempt securities |  | 70,606 |  |  | — |  |  | 70,606 |  |  | — |
Asset-backed securities |  | 193,271 |  |  | — |  |  | 193,271 |  |  | — |
Other trading securities |  | 11,987 |  |  | — |  |  | 11,987 |  |  | — |
Total trading securities |  | 1,909,615 |  |  | — |  |  | 1,909,615 |  |  | — |
Available for sale securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury |  | 490 |  |  | 490 |  |  | — |  |  | — |
Municipal and other tax-exempt securities |  | 10,697 |  |  | — |  |  | 8,667 |  |  | 2,030 |
U.S. government agency residential mortgage-backed securities |  | 5,304,560 |  |  | — |  |  | 5,304,560 |  |  | — |
Privately issued residential mortgage-backed securities |  | 83,224 |  |  | — |  |  | 83,224 |  |  | — |
Commercial mortgage-backed securities guaranteed by U.S. government agencies |  | 2,738,451 |  |  | — |  |  | 2,738,451 |  |  | — |
Other debt securities |  | 25,444 |  |  | — |  |  | 24,973 |  |  | 471 |
Total available for sale securities |  | 8,162,866 |  |  | 490 |  |  | 8,159,875 |  |  | 2,501 |
Fair value option securities – U.S. government agency residential mortgage-backed securities |  | 482,227 |  |  | — |  |  | 482,227 |  |  | — |
Residential mortgage loans held for sale |  | 223,301 |  |  | — |  |  | 209,058 |  |  | 14,243 |
Mortgage servicing rights1 |  | 278,719 |  |  | — |  |  | — |  |  | 278,719 |
Derivative contracts, net of cash collateral2 |  | 373,373 |  |  | 21,056 |  |  | 352,317 |  |  | — |
Liabilities: |  |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral2 |  | 234,856 |  |  | 17,214 |  |  | 217,642 |  |  | — |
1 | A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.
2 | See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts in asset positions that were valued based on quoted prices in active markets for identical instruments (Level 1) are primarily exchange-traded interest rate and agricultural derivative contacts, net of cah margin. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded energy and interest rate derivative contracts, net of cash margin.
The fair value of financial assets and liabilities measured on a recurring basis was as follows as of December 31, 2017 (in thousands):
|  | Total |  | Quoted Prices in Active Markets for Identical Instruments (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
Assets: |  |  |  |  |  |  |  |
Trading securities: |  |  |  |  |  |  |  |
U.S. government agency debentures |  | $ | 21,196 |  |  | $ | — |  |  | $ | 21,196 |  |  | $ | — |
U.S. government agency residential mortgage-backed securities |  | 392,673 |  |  | — |  |  | 392,673 |  |  | — |
Municipal and other tax-exempt securities |  | 13,559 |  |  | — |  |  | 13,559 |  |  | — |
Asset-backed securities |  | 23,885 |  |  | — |  |  | 23,885 |  |  | — |
Other trading securities |  | 11,363 |  |  | — |  |  | 11,363 |  |  | — |
Total trading securities |  | 462,676 |  |  | — |  |  | 462,676 |  |  | — |
Available for sale securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury |  | 1,000 |  |  | 1,000 |  |  | — |  |  | — |
Municipal and other tax-exempt securities |  | 27,080 |  |  | — |  |  | 22,278 |  |  | 4,802 |
U.S. government agency residential mortgage-backed securities |  | 5,309,152 |  |  | — |  |  | 5,309,152 |  |  | — |
Privately issued residential mortgage-backed securities |  | 93,221 |  |  | — |  |  | 93,221 |  |  | — |
Commercial mortgage-backed securities guaranteed by U.S. government agencies |  | 2,834,961 |  |  | — |  |  | 2,834,961 |  |  | — |
Other debt securities |  | 25,481 |  |  | — |  |  | 25,009 |  |  | 472 |
Perpetual preferred stock |  | 15,767 |  |  | — |  |  | 15,767 |  |  | — |
Equity securities and mutual funds |  | 14,916 |  |  | — |  |  | 14,916 |  |  | — |
Total available for sale securities |  | 8,321,578 |  |  | 1,000 |  |  | 8,315,304 |  |  | 5,274 |
Fair value option securities – U.S. government agency residential mortgage-backed securities |  | 755,054 |  |  | — |  |  | 755,054 |  |  | — |
Residential mortgage loans held for sale |  | 221,378 |  |  | — |  |  | 209,079 |  |  | 12,299 |
Mortgage servicing rights1 |  | 252,867 |  |  | — |  |  | — |  |  | 252,867 |
Derivative contracts, net of cash collateral2 |  | 220,502 |  |  | 8,179 |  |  | 212,323 |  |  | — |
Liabilities: |  |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral2 |  | 171,963 |  |  | — |  |  | 171,963 |  |  | — |
1 | A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.
2 | See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate, energy and agricultural derivative contacts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and energy derivative contracts, fully offset by cash margin.
The fair value of financial assets and liabilities measured on a recurring basis was as follows as of June 30, 2017 (in thousands):
|  | Total |  | Quoted Prices in Active Markets for Identical Instruments (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
Assets: |  |  |  |  |  |  |  |
Trading securities: |  |  |  |  |  |  |  |
U.S. government agency debentures |  | $ | 20,954 |  |  | $ | — |  |  | $ | 20,954 |  |  | $ | — |
U.S. government agency residential mortgage-backed securities |  | 365,171 |  |  | — |  |  | 365,171 |  |  | — |
Municipal and other tax-exempt securities |  | 45,444 |  |  | — |  |  | 45,444 |  |  | — |
Other trading securities |  | 9,845 |  |  | — |  |  | 9,845 |  |  | — |
Total trading securities |  | 441,414 |  |  | — |  |  | 441,414 |  |  | — |
Available for sale securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury |  | 998 |  |  | 998 |  |  | — |  |  | — |
Municipal and other tax-exempt securities |  | 32,765 |  |  | — |  |  | 28,110 |  |  | 4,655 |
U.S. government agency residential mortgage-backed securities |  | 5,382,377 |  |  | — |  |  | 5,382,377 |  |  | — |
Privately issued residential mortgage-backed securities |  | 103,383 |  |  | — |  |  | 103,383 |  |  | — |
Commercial mortgage-backed securities guaranteed by U.S. government agencies |  | 2,782,070 |  |  | — |  |  | 2,782,070 |  |  | — |
Other debt securities |  | 4,152 |  |  | — |  |  | — |  |  | 4,152 |
Perpetual preferred stock |  | 16,568 |  |  | — |  |  | 16,568 |  |  | — |
Equity securities and mutual funds |  | 18,728 |  |  | 3,516 |  |  | 15,212 |  |  | — |
Total available for sale securities |  | 8,341,041 |  |  | 4,514 |  |  | 8,327,720 |  |  | 8,807 |
Fair value option securities – U.S. government agency residential mortgage-backed securities |  | 445,169 |  |  | — |  |  | 445,169 |  |  | — |
Residential mortgage loans held for sale |  | 287,259 |  |  | — |  |  | 274,524 |  |  | 12,735 |
Mortgage servicing rights1 |  | 245,239 |  |  | — |  |  | — |  |  | 245,239 |
Derivative contracts, net of cash collateral2 |  | 280,289 |  |  | 46,366 |  |  | 233,923 |  |  | — |
Liabilities: |  |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral2 |  | 285,819 |  |  | 20,915 |  |  | 264,904 |  |  | — |
1 | A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 6, Mortgage Banking Activities.
2 | See Note 3 for detail of fair value of derivative contracts by contract type. Derivative contracts based on quoted prices in active markets for identical instruments (Level 1) are exchange-traded energy and interest rate derivative contacts. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate and agricultural derivative contracts, net cash margin.
Fair Value Assets Measured On Recurring Basis, Significant Unobservable Inputs [Table Text Block] | The following represents the changes for the three and six months ended June 30, 2018 related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands):
|  | Available for Sale Securities |  |
|  | Municipal and other tax-exempt securities |  | Other debt securities |  | Residential mortgage loans held for sale
Balance, March 31, 2018 |  | $ | 1,891 |  |  | $ | 472 |  |  | $ | 13,871 |
Transfer to Level 3 from Level 21 |  | — |  |  | — |  |  | 687 |
Purchases |  | — |  |  | — |  |  | — |
Proceeds from sales |  | — |  |  | — |  |  | (488 | )
Redemptions and distributions |  | — |  |  | — |  |  | — |
Gain (loss) recognized in earnings: |  |  |  |  |  |
Mortgage banking revenue |  | — |  |  | — |  |  | 173 |
Other comprehensive income: |  |  |  |  |  |
Net change in unrealized gain |  | 139 |  |  | (1 | ) |  | — |
Balance, June 30, 2018 |  | $ | 2,030 |  |  | $ | 471 |  |  | $ | 14,243 |
1 | Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
|  | Available for Sale Securities |  |
|  | Municipal and other tax-exempt |  | Other debt securities |  | Residential mortgage loans held for sale
Balance, December 31, 2017 |  | $ | 4,802 |  |  | $ | 472 |  |  | $ | 12,299 |
Transfer to Level 3 from Level 21 |  | — |  |  | — |  |  | 2,843 |
Purchases |  | — |  |  | — |  |  | — |
Proceeds from sales |  | — |  |  | — |  |  | (812 | )
Redemptions and distributions |  | (3,045 | ) |  | — |  |  | — |
Gain (loss) recognized in earnings: |  |  |  |  |  |
Mortgage banking revenue |  | — |  |  | — |  |  | (87 | )
Other comprehensive income (loss): |  |  |  |  |  |
Net change in unrealized gain (loss) |  | 273 |  |  | (1 | ) |  | — |
Balance, June 30, 2018 |  | $ | 2,030 |  |  | $ | 471 |  |  | $ | 14,243 |
1 | Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
The following represents the changes for the three and six months ended June 30, 2017 related to assets measured at fair value on a recurring basis using significant unobservable inputs (in thousands):
|  | Available for Sale Securities |  |
|  | Municipal and other tax-exempt securities |  | Other debt securities |  | Residential mortgage loans held for sale
Balance, March 31, 2017 |  | $ | 5,722 |  |  | $ | 4,153 |  |  | $ | 12,679 |
Transfer to Level 3 from Level 21 |  | — |  |  | — |  |  | 853 |
Purchases |  | — |  |  | — |  |  | — |
Proceeds from sales |  | — |  |  | — |  |  | (1,030 | )
Redemptions and distributions |  | (1,100 | ) |  | — |  |  | — |
Gain (loss) recognized in earnings: |  |  |  |  |  |
Mortgage banking revenue |  | — |  |  | — |  |  | 233 |
Other comprehensive income (loss): |  |  |  |  |  |
Net change in unrealized gain (loss) |  | 33 |  |  | (1 | ) |  | — |
Balance, June 30, 2017 |  | $ | 4,655 |  |  | $ | 4,152 |  |  | $ | 12,735 |
1 | Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
|  | Available for Sale Securities |  |
|  | Municipal and other tax-exempt |  | Other debt securities |  | Residential mortgage loans held for sale
Balance, December 31, 2016 |  | $ | 5,789 |  |  | $ | 4,152 |  |  | $ | 11,617 |
Transfer to Level 3 from Level 21 |  | — |  |  | — |  |  | 2,740 |
Purchases |  | — |  |  | — |  |  | — |
Proceeds from sales |  | — |  |  | — |  |  | (1,702 | )
Redemptions and distributions |  | (1,100 | ) |  | — |  |  | — |
Gain (loss) recognized in earnings |  |  |  |  |  |
Mortgage banking revenue |  | — |  |  | — |  |  | 80 |
Other comprehensive income (loss): |  |  |  |  |  |
Net change in unrealized gain (loss) |  | (34 | ) |  | — |  |  | — |
Balance, June 30, 2017 |  | $ | 4,655 |  |  | $ | 4,152 |  |  | $ | 12,735 |
1 | Recurring transfers to Level 3 from Level 2 consist of residential mortgage loans intended for sale to U.S. government agencies that fail to meet conforming standards.
Fair Value Inputs, Fair Value Measured On a Recurring Basis, Quantitative Information [Table Text Block] | A summary of quantitative information about assets measured at fair value on a recurring basis using Significant Unobservable Inputs (Level 3) as of June 30, 2018 follows (in thousands):
|  | Par Value |  | Amortized Cost/Unpaid Principal Balance |  | Fair Value |  | Valuation Technique(s) |  | Unobservable Input |  | Range (Weighted Average) |
Available for sale securities |  |  |  |  |  |  |  |  |  |  |  |  |
Municipal and other tax-exempt securities |  | $ | 2,050 |  |  | $ | 2,033 |  |  | $ | 2,030 |  |  | Discounted cash flows | 1 | Interest rate spread |  | 6.69%-6.69% (6.69%) | 2
99.00%-99.00% (99.00%) | 3
Other debt securities |  | 500 |  |  | 500 |  |  | 471 |  |  | Discounted cash flows | 1 | Interest rate spread |  | 6.32%-6.32% (6.32%) | 4
94.36% - 94.36 (94.36%) | 3
Residential mortgage loans held for sale |  | N/A |  |  | 15,025 |  |  | 14,252 |  |  | Quoted prices of loans sold in securitization transactions, with a liquidity discount applied |  | Liquidity discount applied to the market value of mortgage loans qualifying for sale to U.S. government agencies. |  | 94.86% |
1 | Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.
2 | Interest rate yields used to value investment grade tax-exempt securities represent a spread of 413 basis points over average yields for comparable tax-exempt securities.
3 | Represents fair value as a percentage of par value.
4 | Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.
A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of December 31, 2017 follows (in thousands):
|  | Par Value |  | Amortized Cost/Unpaid Principal Balance |  | Fair Value |  | Valuation Technique(s) |  | Unobservable Input |  | Range (Weighted Average) |
Available for sale securities |  |  |  |  |  |  |  |  |  |  |  |  |
Municipal and other tax-exempt securities |  | $ | 5,095 |  |  | $ | 5,068 |  |  | $ | 4,802 |  |  | Discounted cash flows | 1 | Interest rate spread |  | 6.60%-6.60% (6.60%) | 2
92.25%-94.76% (93.75%) | 3
Other debt securities |  | 500 |  |  | 500 |  |  | 472 |  |  | Discounted cash flows | 1 | Interest rate spread |  | 6.85%-6.85% (6.85%) | 4
94.39% - 94.39 (94.39%) | 3
Residential mortgage loans held for sale |  | N/A |  |  | 12,981 |  |  | 12,299 |  |  | Quoted prices of loans sold in securitization transactions, with a liquidity discount applied |  | Liquidity discount applied to the market value of mortgage loans qualifying for sale to U.S. government agencies. |  | 94.75% |
1 | Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.
2 | Interest rate yields used to value investment grade tax-exempt securities represent a spread of 372 to 466 basis points over average yields for comparable tax-exempt securities.
3 | Represents fair value as a percentage of par value.
4 | Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.
A summary of quantitative information about Recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2017 follows (in thousands):
|  | Par Value |  | Amortized Cost |  | Fair Value |  | Valuation Technique(s) |  | Unobservable Input |  | Range (Weighted Average) |
Available for sale securities |  |  |  |  |  |  |  |  |  |  |  |  |
Municipal and other tax-exempt securities |  | $ | 5,095 |  |  | $ | 5,067 |  |  | $ | 4,655 |  |  | Discounted cash flows | 1 | Interest rate spread |  | 5.98%-5.98% (5.98%) | 2
90.00%-94.90% (92.93%) | 3
Other debt securities |  | 4,400 |  |  | 4,400 |  |  | 4,152 |  |  | Discounted cash flows | 1 | Interest rate spread |  | 5.41%-6.72% (6.57%) | 4
94.31% - 94.38 (94.37%) | 3
Residential mortgage loans held for sale |  | N/A |  |  | 13,274 |  |  | 12,735 |  |  | Quoted prices of loans sold in securitization transactions, with a liquidity discount applied |  | Liquidity discount applied to the market value of a mortgage loans qualifying for sale to U.S. government agencies. |  | 95.94% |
1 | Discounted cash flows developed using discount rates primarily based on reference to interest rate spreads for comparable securities of similar duration and credit rating as determined by the nationally-recognized rating agencies, adjusted for lack of trading volume.
2 | Interest rate yields used to value investment grade tax-exempt securities represent a spread of 360 to 446 basis points over average yields for comparable tax-exempt securities.
3 | Represents fair value as a percentage of par value.
4 | Interest rate yields used to value investment grade taxable securities based on comparable short-term taxable securities which are generally yielding less than 3 percent.
Fair Value Assets Measured on Nonrecurring Basis [Table Text Block] | The following represents the carrying value of assets measured at fair value on a non-recurring basis (and related losses) during the period. The carrying value represents only those assets with a balance at June 30, 2018 for which the fair value was adjusted during the six months ended June 30, 2018:
|  |  |  |  |  |  | Fair Value Adjustments for the
| Carrying Value at June 30, 2018 |  | Three Months Ended June 30, 2018 Recognized in: |  | Six Months Ended June 30, 2018 Recognized in:
| Quoted Prices in Active Markets for Identical Instruments |  | Significant Other Observable Inputs |  | Significant Unobservable Inputs |  | Gross charge-offs against allowance for loan losses |  | Net losses and expenses of repossessed assets, net |  | Gross charge-offs against allowance for loan losses |  | Net losses and expenses of repossessed assets, net
Impaired loans | $ | — |  |  | $ | 1,045 |  |  | $ | 11,763 |  |  | $ | 6,701 |  |  | $ | — |  |  | $ | 7,198 |  |  | $ | — |
Real estate and other repossessed assets | — |  |  | 1,996 |  |  | 6,838 |  |  | — |  |  | 118 |  |  | — |  |  | 5,242 |
The following represents the carrying value of assets measured at fair value on a non-recurring basis (and related losses) during the period. The carrying value represents only those assets with a balance at June 30, 2017 for which the fair value was adjusted during the six months ended June 30, 2017:
|  |  |  |  |  |  | Fair Value Adjustments for the
| Carrying Value at June 30, 2017 |  | Three Months Ended June 30, 2017 Recognized in: |  | Six Months Ended June 30, 2017 Recognized in:
| Quoted Prices in Active Markets for Identical Instruments |  | Significant Other Observable Inputs |  | Significant Unobservable Inputs |  | Gross charge-offs against allowance for loan losses |  | Net losses and expenses of repossessed assets, net |  | Gross charge-offs against allowance for loan losses |  | Net losses and expenses of repossessed assets, net
Impaired loans | $ | — |  |  | $ | 464 |  |  | $ | 3,570 |  |  | $ | 232 |  |  | $ | — |  |  | $ | 676 |  |  | $ | — |
Real estate and other repossessed assets | — |  |  | 3,488 |  |  | 530 |  |  | — |  |  | 772 |  |  | — |  |  | 906 |
Fair Value Inputs, Fair Value Measured On a Nonrecurring Basis, Quantitative Information [Table Text Block] | A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2018 follows (in thousands):
|  | Fair Value |  | Valuation Technique(s) |  | Unobservable Input |  | Range (Weighted Average)
Impaired loans |  | $ | 11,763 |  |  | Discounted cash flows |  | Management knowledge of industry and non-real estate collateral including but not limited to recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs |  | 43% - 84% (53%)1
Real estate and other repossessed assets |  | 6,838 |  |  | Discounted cash flows |  | Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs |  | N/A
1 | Represents fair value as a percentage of the unpaid principal balance.
A summary of quantitative information about Non-recurring Fair Value Measurements based on Significant Unobservable Inputs (Level 3) as of June 30, 2017 follows (in thousands):
|  | Fair Value |  | Valuation Technique(s) |  | Unobservable Input |  | Range (Weighted Average)
Impaired loans |  | $ | 3,570 |  |  | Discounted cash flows |  | Recoverable oil and gas reserves, forward-looking commodity prices, estimated operating costs |  | 75% - 90% (83%)1
Real estate and other repossessed assets |  | 530 |  |  | Appraised value, as adjusted |  | Marketability adjustments off appraised value2 |  | 65% - 88% (80%)
1 | Represents fair value as a percentage of the unpaid principal balance.
2 | Marketability adjustments include consideration of estimated costs to sell which is approximately 10% of the fair value.
Fair Value of Financial Instruments [Table Text Block] | The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of June 30, 2018 (dollars in thousands):
|  | Carrying Value |  | Estimated Fair Value |  | Quoted Prices in Active Markets for Identical Instruments (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
Cash and due from banks |  | $ | 585,801 |  |  | $ | 585,801 |  |  | $ | 585,801 |  |  | $ | — |  |  | $ | — |
Interest-bearing cash and cash equivalents |  | 872,999 |  |  | 872,999 |  |  | 872,999 |  |  | — |  |  | — |
Trading securities: |  |  |  |  |  |  |  |  |  |
U.S. government agency debentures |  | 28,750 |  |  | 28,750 |  |  | — |  |  | 28,750 |  |  | — |
U.S. government agency residential mortgage-backed securities |  | 1,605,001 |  |  | 1,605,001 |  |  | — |  |  | 1,605,001 |  |  | — |
Municipal and other tax-exempt securities |  | 70,606 |  |  | 70,606 |  |  | — |  |  | 70,606 |  |  | — |
Asset-backed securities |  | 193,271 |  |  | 193,271 |  |  | — |  |  | 193,271 |  |  | — |
Other trading securities |  | 11,987 |  |  | 11,987 |  |  | — |  |  | 11,987 |  |  | — |
Total trading securities |  | 1,909,615 |  |  | 1,909,615 |  |  | — |  |  | 1,909,615 |  |  | — |
Investment securities: |  |  |  |  |  |  |  |  |  |  |  |
Municipal and other tax-exempt securities |  | 173,097 |  |  | 174,205 |  |  | — |  |  | 174,205 |  |  | — |
U.S. government agency residential mortgage-backed securities |  | 13,989 |  |  | 13,984 |  |  | — |  |  | 13,984 |  |  | — |
Other debt securities |  | 204,927 |  |  | 215,195 |  |  | — |  |  | 215,195 |  |  | — |
Total investment securities |  | 392,013 |  |  | 403,384 |  |  | — |  |  | 403,384 |  |  | — |
Available for sale securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury |  | 490 |  |  | 490 |  |  | 490 |  |  | — |  |  | — |
Municipal and other tax-exempt securities |  | 10,697 |  |  | 10,697 |  |  | — |  |  | 8,667 |  |  | 2,030 |
U.S. government agency residential mortgage-backed securities |  | 5,304,560 |  |  | 5,304,560 |  |  | — |  |  | 5,304,560 |  |  | — |
Privately issued residential mortgage-backed securities |  | 83,224 |  |  | 83,224 |  |  | — |  |  | 83,224 |  |  | — |
Commercial mortgage-backed securities guaranteed by U.S. government agencies |  | 2,738,451 |  |  | 2,738,451 |  |  | — |  |  | 2,738,451 |  |  | — |
Other debt securities |  | 25,444 |  |  | 25,444 |  |  | — |  |  | 24,973 |  |  | 471 |
Total available for sale securities |  | 8,162,866 |  |  | 8,162,866 |  |  | 490 |  |  | 8,159,875 |  |  | 2,501 |
Fair value option securities – U.S. government agency residential mortgage-backed securities |  | 482,227 |  |  | 482,227 |  |  | — |  |  | 482,227 |  |  | — |
Residential mortgage loans held for sale |  | 223,301 |  |  | 223,301 |  |  | — |  |  | 209,058 |  |  | 14,243 |
Loans: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | 11,349,039 |  |  | 11,116,828 |  |  | — |  |  | — |  |  | 11,116,828 |
Commercial real estate |  | 3,712,220 |  |  | 3,639,121 |  |  | — |  |  | — |  |  | 3,639,121 |
Residential mortgage |  | 1,942,250 |  |  | 1,917,099 |  |  | — |  |  | — |  |  | 1,917,099 |
Personal |  | 1,000,187 |  |  | 990,419 |  |  | — |  |  | — |  |  | 990,419 |
Total loans |  | 18,003,696 |  |  | 17,663,467 |  |  | — |  |  | — |  |  | 17,663,467 |
Allowance for loan losses |  | (215,142 | ) |  | — |  |  | — |  |  | — |  |  | — |
Loans, net of allowance |  | 17,788,554 |  |  | 17,663,467 |  |  | — |  |  | — |  |  | 17,663,467 |
Mortgage servicing rights |  | 278,719 |  |  | 278,719 |  |  | — |  |  | — |  |  | 278,719 |
Derivative instruments with positive fair value, net of cash collateral |  | 373,373 |  |  | 373,373 |  |  | 21,056 |  |  | 352,317 |  |  | — |
Deposits with no stated maturity |  | 20,041,532 |  |  | 20,041,532 |  |  | — |  |  | — |  |  | 20,041,532 |
Time deposits |  | 2,127,732 |  |  | 2,078,486 |  |  | — |  |  | — |  |  | 2,078,486 |
Other borrowed funds |  | 6,809,472 |  |  | 6,571,762 |  |  | — |  |  | — |  |  | 6,571,762 |
Subordinated debentures |  | 144,697 |  |  | 148,112 |  |  | — |  |  | 148,112 |  |  | — |
Derivative instruments with negative fair value, net of cash collateral |  | 234,856 |  |  | 234,856 |  |  | 17,214 |  |  | 217,642 |  |  | — |
The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of December 31, 2017 (dollars in thousands):
|  | Carrying Value |  | Estimated Fair Value |  | Quoted Prices in Active Markets for Identical Instruments (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
Cash and due from banks |  | $ | 602,510 |  |  | $ | 602,510 |  |  | $ | 602,510 |  |  | $ | — |  |  | $ | — |
Interest-bearing cash and cash equivalents |  | 1,714,544 |  |  | 1,714,544 |  |  | 1,714,544 |  |  | — |  |  | — |
Trading securities: |  |  |  |  |  |  |  |  |  |
U.S. government agency debentures |  | 21,196 |  |  | 21,196 |  |  | — |  |  | 21,196 |  |  | — |
U.S. government agency residential mortgage-backed securities |  | 392,673 |  |  | 392,673 |  |  | — |  |  | 392,673 |  |  | — |
Municipal and other tax-exempt securities |  | 13,559 |  |  | 13,559 |  |  | — |  |  | 13,559 |  |  | — |
Asset-backed securities |  | 23,885 |  |  | 23,885 |  |  | — |  |  | 23,885 |  |  | — |
Other trading securities |  | 11,363 |  |  | 11,363 |  |  | — |  |  | 11,363 |  |  | — |
Total trading securities |  | 462,676 |  |  | 462,676 |  |  | — |  |  | 462,676 |  |  | — |
Investment securities: |  |  |  |  |  |  |  |  |  |  |  |
Municipal and other tax-exempt securities |  | 228,186 |  |  | 230,349 |  |  | — |  |  | 230,349 |  |  | — |
U.S. government agency residential mortgage-backed securities |  | 15,891 |  |  | 16,242 |  |  | — |  |  | 16,242 |  |  | — |
Other debt securities |  | 217,716 |  |  | 233,444 |  |  | — |  |  | 233,444 |  |  | — |
Total investment securities |  | 461,793 |  |  | 480,035 |  |  | — |  |  | 480,035 |  |  | — |
Available for sale securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury |  | 1,000 |  |  | 1,000 |  |  | 1,000 |  |  | — |  |  | — |
Municipal and other tax-exempt securities |  | 27,080 |  |  | 27,080 |  |  | — |  |  | 22,278 |  |  | 4,802 |
U.S. government agency residential mortgage-backed securities |  | 5,309,152 |  |  | 5,309,152 |  |  | — |  |  | 5,309,152 |  |  | — |
Privately issued residential mortgage-backed securities |  | 93,221 |  |  | 93,221 |  |  | — |  |  | 93,221 |  |  | — |
Commercial mortgage-backed securities guaranteed by U.S. government agencies |  | 2,834,961 |  |  | 2,834,961 |  |  | — |  |  | 2,834,961 |  |  | — |
Other debt securities |  | 25,481 |  |  | 25,481 |  |  | — |  |  | 25,009 |  |  | 472 |
Perpetual preferred stock |  | 15,767 |  |  | 15,767 |  |  | — |  |  | 15,767 |  |  | — |
Equity securities and mutual funds |  | 14,916 |  |  | 14,916 |  |  | — |  |  | 14,916 |  |  | — |
Total available for sale securities |  | 8,321,578 |  |  | 8,321,578 |  |  | 1,000 |  |  | 8,315,304 |  |  | 5,274 |
Fair value option securities – U.S. government agency residential mortgage-backed securities |  | 755,054 |  |  | 755,054 |  |  | — |  |  | 755,054 |  |  | — |
Residential mortgage loans held for sale |  | 221,378 |  |  | 221,378 |  |  | — |  |  | 209,079 |  |  | 12,299 |
Loans: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | 10,733,975 |  |  | 10,524,627 |  |  | — |  |  | — |  |  | 10,524,627 |
Commercial real estate |  | 3,479,987 |  |  | 3,428,733 |  |  | — |  |  | — |  |  | 3,428,733 |
Residential mortgage |  | 1,973,686 |  |  | 1,977,721 |  |  | — |  |  | — |  |  | 1,977,721 |
Personal |  | 965,776 |  |  | 956,706 |  |  | — |  |  | — |  |  | 956,706 |
Total loans |  | 17,153,424 |  |  | 16,887,787 |  |  | — |  |  | — |  |  | 16,887,787 |
Allowance for loan losses |  | (230,682 | ) |  | — |  |  | — |  |  | — |  |  | — |
Loans, net of allowance |  | 16,922,742 |  |  | 16,887,787 |  |  | — |  |  | — |  |  | 16,887,787 |
Mortgage servicing rights |  | 252,867 |  |  | 252,867 |  |  | — |  |  | — |  |  | 252,867 |
Derivative instruments with positive fair value, net of cash collateral |  | 220,502 |  |  | 220,502 |  |  | 8,179 |  |  | 212,323 |  |  | — |
Deposits with no stated maturity |  | 19,962,889 |  |  | 19,962,889 |  |  | — |  |  | — |  |  | 19,962,889 |
Time deposits |  | 2,098,416 |  |  | 2,064,558 |  |  | — |  |  | — |  |  | 2,064,558 |
Other borrowed funds |  | 5,709,861 |  |  | 5,703,121 |  |  | — |  |  | — |  |  | 5,703,121 |
Subordinated debentures |  | 144,677 |  |  | 148,207 |  |  | — |  |  | 148,207 |  |  | — |
Derivative instruments with negative fair value, net of cash collateral |  | 171,963 |  |  | 171,963 |  |  | — |  |  | 171,963 |  |  | — |
The following table presents the carrying values and estimated fair values of all financial instruments, including those financial assets and liabilities that are not measured and reported at fair value on a recurring basis or non-recurring basis as of June 30, 2017 (dollars in thousands):
|  | Carrying Value |  | Estimated Fair Value |  | Quoted Prices in Active Markets for Identical Instruments (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
Cash and due from banks |  | $ | 561,587 |  |  | $ | 561,587 |  |  | $ | 561,587 |  |  | $ | — |  |  | $ | — |
Interest-bearing cash and cash equivalents |  | 2,078,831 |  |  | 2,078,831 |  |  | 2,078,831 |  |  | — |  |  | — |
Trading securities: |  |  |  |  |  |  |  |  |  |
U.S. government agency debentures |  | 20,954 |  |  | 20,954 |  |  | — |  |  | 20,954 |  |  | — |
U.S. government agency residential mortgage-backed securities |  | 365,171 |  |  | 365,171 |  |  | — |  |  | 365,171 |  |  | — |
Municipal and other tax-exempt securities |  | 45,444 |  |  | 45,444 |  |  | — |  |  | 45,444 |  |  | — |
Other trading securities |  | 9,845 |  |  | 9,845 |  |  | — |  |  | 9,845 |  |  | — |
Total trading securities |  | 441,414 |  |  | 441,414 |  |  | — |  |  | 441,414 |  |  | — |
Investment securities: |  |  |  |  |  |  |  |  |  |  |  |
Municipal and other tax-exempt securities |  | 267,375 |  |  | 270,531 |  |  | — |  |  | 270,531 |  |  | — |
U.S. government agency residential mortgage-backed securities |  | 18,035 |  |  | 18,642 |  |  | — |  |  | 18,642 |  |  | — |
Other debt securities |  | 205,016 |  |  | 226,502 |  |  | — |  |  | 226,502 |  |  | — |
Total investment securities |  | 490,426 |  |  | 515,675 |  |  | — |  |  | 515,675 |  |  | — |
Available for sale securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury |  | 998 |  |  | 998 |  |  | 998 |  |  | — |  |  | — |
Municipal and other tax-exempt securities |  | 32,765 |  |  | 32,765 |  |  | — |  |  | 28,110 |  |  | 4,655 |
U.S. government agency residential mortgage-backed securities |  | 5,382,377 |  |  | 5,382,377 |  |  | — |  |  | 5,382,377 |  |  | — |
Privately issued residential mortgage-backed securities |  | 103,383 |  |  | 103,383 |  |  | — |  |  | 103,383 |  |  | — |
Commercial mortgage-backed securities guaranteed by U.S. government agencies |  | 2,782,070 |  |  | 2,782,070 |  |  | — |  |  | 2,782,070 |  |  | — |
Other debt securities |  | 4,152 |  |  | 4,152 |  |  | — |  |  | — |  |  | 4,152 |
Perpetual preferred stock |  | 16,568 |  |  | 16,568 |  |  | — |  |  | 16,568 |  |  | — |
Equity securities and mutual funds |  | 18,728 |  |  | 18,728 |  |  | 3,516 |  |  | 15,212 |  |  | — |
Total available for sale securities |  | 8,341,041 |  |  | 8,341,041 |  |  | 4,514 |  |  | 8,327,720 |  |  | 8,807 |
Fair value option securities – U.S. government agency residential mortgage-backed securities |  | 445,169 |  |  | 445,169 |  |  | — |  |  | 445,169 |  |  | — |
Residential mortgage loans held for sale |  | 287,259 |  |  | 287,259 |  |  | — |  |  | 274,524 |  |  | 12,735 |
Loans: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | 10,637,955 |  |  | 10,413,704 |  |  | — |  |  | — |  |  | 10,413,704 |
Commercial real estate |  | 3,688,592 |  |  | 3,636,365 |  |  | — |  |  | — |  |  | 3,636,365 |
Residential mortgage |  | 1,939,198 |  |  | 1,950,577 |  |  | — |  |  | — |  |  | 1,950,577 |
Personal |  | 917,900 |  |  | 909,055 |  |  | — |  |  | — |  |  | 909,055 |
Total loans |  | 17,183,645 |  |  | 16,909,701 |  |  | — |  |  | — |  |  | 16,909,701 |
Allowance for loan losses |  | (250,061 | ) |  | — |  |  | — |  |  | — |  |  | — |
Loans, net of allowance |  | 16,933,584 |  |  | 16,909,701 |  |  | — |  |  | — |  |  | 16,909,701 |
Mortgage servicing rights |  | 245,239 |  |  | 245,239 |  |  | — |  |  | — |  |  | 245,239 |
Derivative instruments with positive fair value, net of cash collateral |  | 280,289 |  |  | 280,289 |  |  | 46,366 |  |  | 233,923 |  |  | — |
Deposits with no stated maturity |  | 20,120,352 |  |  | 20,120,352 |  |  | — |  |  | — |  |  | 20,120,352 |
Time deposits |  | 2,196,122 |  |  | 2,164,115 |  |  | — |  |  | — |  |  | 2,164,115 |
Other borrowed funds |  | 5,696,666 |  |  | 5,664,273 |  |  | — |  |  | — |  |  | 5,664,273 |
Subordinated debentures |  | 144,658 |  |  | 147,204 |  |  | — |  |  | 147,204 |  |  | — |
Derivative instruments with negative fair value, net of cash collateral |  | 285,819 |  |  | 285,819 |  |  | 20,915 |  |  | 264,904 |  |  | — |

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