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Fair Value Measurements, Fair Value Of Financial Instruments as Measured On a Recurring Basis (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Jun. 30, 2019 | Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | --- | --- | --- | --- | ---
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | $ 1,675,212 |  |  | $ 1,956,923 |  |  |  |
Available for sale securities | 11,024,551 |  |  | 8,857,120 |  |  |  |
Fair value option securities | 1,816,398 |  |  | 283,235 |  |  |  |
Mortgage servicing rights | 193,661 |  | $ 208,308 | 259,254 |  | $ 284,673 | $ 278,719 | $ 252,867
Derviative contracts, net of cash collateral, Assets, Fair value | 352,019 |  |  | 320,929 |  |  |  |
Liabilities: [Abstract] |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral, Liabilities, Fair Value | 336,791 |  |  | 362,306 |  |  |  |
U.S. government agency debentures [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 63,334 |  |  | 63,765 |  |  |  |
Residential agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 1,480,458 |  |  | 1,791,584 |  |  |  |
Available for sale securities | 7,740,461 |  |  | 5,804,708 |  |  |  |
Fair value option securities | 1,263,862 |  |  | 283,235 |  |  |  |
Municipal and other tax-exempt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 44,105 |  |  | 34,507 |  |  |  |
Available for sale securities | 1,848 |  |  | 2,864 |  |  |  |
Asset-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 36,928 |  |  | 42,656 |  |  |  |
U.S. Treasury [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 2,296 |  |  | 493 |  |  |  |
Fair value option securities | 552,536 |  |  | 0 |  |  |  |
Residential non-agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 44,803 |  |  | 59,736 |  |  |  |
Commercial agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 3,234,671 |  |  | 2,953,889 |  |  |  |
Other debt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 50,387 |  |  | 24,411 |  |  |  |
Available for sale securities | 472 |  |  | 35,430 |  |  |  |
Fair Value, Recurring [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 1,675,212 |  |  | 1,956,923 |  |  |  |
Available for sale securities | 11,024,551 |  |  | 8,857,120 |  |  |  |
Fair value option securities | 1,816,398 |  |  |  |  |  |  |
Residential mortgage loans held for sale | 282,487 |  |  | 149,221 |  |  |  |
Mortgage servicing rights | 193,661 | [1] |  | 259,254 | [2] |  |  |
Derviative contracts, net of cash collateral, Assets, Fair value | 352,019 | [3] |  | 320,929 | [4] |  |  |
Liabilities: [Abstract] |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral, Liabilities, Fair Value | 336,791 | [3] |  | 362,306 | [4] |  |  |
Fair Value, Recurring [Member] | U.S. government agency debentures [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 63,334 |  |  | 63,765 |  |  |  |
Fair Value, Recurring [Member] | Residential agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 1,480,458 |  |  | 1,791,584 |  |  |  |
Available for sale securities | 7,740,461 |  |  | 5,804,708 |  |  |  |
Fair value option securities | 1,263,862 |  |  | 283,235 |  |  |  |
Fair Value, Recurring [Member] | Municipal and other tax-exempt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 44,105 |  |  | 34,507 |  |  |  |
Available for sale securities | 1,848 |  |  | 2,864 |  |  |  |
Fair Value, Recurring [Member] | Asset-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 36,928 |  |  | 42,656 |  |  |  |
Fair Value, Recurring [Member] | U.S. Treasury [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 2,296 |  |  | 493 |  |  |  |
Fair value option securities | 552,536 |  |  |  |  |  |  |
Fair Value, Recurring [Member] | Residential non-agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 44,803 |  |  | 59,736 |  |  |  |
Fair Value, Recurring [Member] | Commercial agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 3,234,671 |  |  | 2,953,889 |  |  |  |
Fair Value, Recurring [Member] | Other debt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 50,387 |  |  | 24,411 |  |  |  |
Available for sale securities | 472 |  |  | 35,430 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | 2,296 |  |  | 493 |  |  |  |
Fair value option securities | 552,536 |  |  |  |  |  |  |
Residential mortgage loans held for sale | 0 |  |  | 0 |  |  |  |
Mortgage servicing rights | 0 | [1] |  | 0 | [2] |  |  |
Derviative contracts, net of cash collateral, Assets, Fair value | 40,491 | [3] |  | 44,074 | [4] |  |  |
Liabilities: [Abstract] |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral, Liabilities, Fair Value | 0 | [3] |  | 0 | [4] |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. government agency debentures [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair value option securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Municipal and other tax-exempt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Treasury [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 2,296 |  |  | 493 |  |  |  |
Fair value option securities | 552,536 |  |  |  |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Residential non-agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Other debt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 1,675,212 |  |  | 1,956,923 |  |  |  |
Available for sale securities | 11,021,783 |  |  | 8,856,155 |  |  |  |
Fair value option securities | 1,263,862 |  |  |  |  |  |  |
Residential mortgage loans held for sale | 268,919 |  |  | 134,014 |  |  |  |
Mortgage servicing rights | 0 | [1] |  | 0 | [2] |  |  |
Derviative contracts, net of cash collateral, Assets, Fair value | 311,528 | [3] |  | 276,855 | [4] |  |  |
Liabilities: [Abstract] |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral, Liabilities, Fair Value | 336,791 | [3] |  | 362,306 | [4] |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. government agency debentures [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 63,334 |  |  | 63,765 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 1,480,458 |  |  | 1,791,584 |  |  |  |
Available for sale securities | 7,740,461 |  |  | 5,804,708 |  |  |  |
Fair value option securities | 1,263,862 |  |  | 283,235 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Municipal and other tax-exempt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 44,105 |  |  | 34,507 |  |  |  |
Available for sale securities | 1,848 |  |  | 2,864 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 36,928 |  |  | 42,656 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Treasury [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair value option securities | 0 |  |  |  |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Residential non-agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 44,803 |  |  | 59,736 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 3,234,671 |  |  | 2,953,889 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Other debt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 50,387 |  |  | 24,411 |  |  |  |
Available for sale securities | 0 |  |  | 34,958 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | 472 |  |  | 472 |  |  |  |
Fair value option securities | 0 |  |  |  |  |  |  |
Residential mortgage loans held for sale | 13,568 |  |  | 15,207 |  |  |  |
Mortgage servicing rights | 193,661 | [1] |  | 259,254 | [2] |  |  |
Derviative contracts, net of cash collateral, Assets, Fair value | 0 | [3] |  | 0 | [4] |  |  |
Liabilities: [Abstract] |  |  |  |  |  |  |  |
Derivative contracts, net of cash collateral, Liabilities, Fair Value | 0 | [3] |  | 0 | [4] |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. government agency debentures [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair value option securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Municipal and other tax-exempt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities |  |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Treasury [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair value option securities | 0 |  |  |  |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential non-agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial agency mortgage-backed securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Available for sale securities | 0 |  |  | 0 |  |  |  |
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Other debt securities [Member] |  |  |  |  |  |  |  |
Assets: [Abstract] |  |  |  |  |  |  |  |
Trading securities | 0 |  |  | 0 |  |  |  |
Available for sale securities | $ 472 |  |  | $ 472 |  |  |  |
[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] | 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.
[3] | 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 energy, interest rate and agricultural derivative contacts, net of cash margin. Derivative contacts in liability positions that were valued using quoted prices in active markets for identical instruments are exchange-traded interest rate derivative contracts, fully offset by cash margin.
[4] | 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, net of cash margin. Derivative contracts in liability positions that were valued using quoted prices in active markets for identical instruments (Level 1) are exchange-traded interest rate contracts, fully offset by cash margin.

X
- Definition Fair value option securities represent securities the Company has elected to carry at fair value and separately identified on the balance sheet with changes in fair value recognized in earnings as they occur. Certain residential mortgage-backed securities issued by US government agencies are held as an economic hedge of changes in the fair value of mortgage servicing rights and related derivative contracts. In addition, other securities may be held to manage interest rate risk or for deferred compensation purposes. Securities held for interest rate risk management may be economically hedged by derivative contracts not designated as hedging instruments effectively modify these fixed rate securities into variable rate securities. + References No definition available. + Details
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13433-108611 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 + Details
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- Definition Fair value portion of mortgage loans held-for-sale. + References No definition available. + Details
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- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=116651436&loc=d3e122625-111746 + Details
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562 + Details
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