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Derivatives, Derivatives Instruments Gain (Loss) in Income Statement (Details) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | $ (37,433) | $ (618)
Gain (Loss) on Derivatives, Net |  | 18,420 | 4,667
Total customer risk management programs |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 3,222 | 6,677
Gain (Loss) on Derivatives, Net |  | 0 | 0
To-be-announced residential mortgage-backed securities [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 0 | 5,700
Gain (Loss) on Derivatives, Net |  | 0 | 0
Interest rate contracts [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 942 | 593
Gain (Loss) on Derivatives, Net |  | 0 | 0
Energy contracts [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 2,007 | 226
Gain (Loss) on Derivatives, Net |  | 0 | 0
Agricultural contracts [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 15 | 4
Gain (Loss) on Derivatives, Net |  | 0 | 0
Foreign exchange contracts [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 258 | 154
Gain (Loss) on Derivatives, Net |  | 0 | 0
Equity option contracts [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 0 | 0
Gain (Loss) on Derivatives, Net |  | 0 | 0
Trading [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue | [1] | (40,655) | (7,295)
Gain (Loss) on Derivatives, Net | [1] | 0 | 0
Internal risk management programs [Member] |  |  |
Derivative Instruments, Gain (Loss) Recognized in Income, Net [Abstract] |  |  |
Brokergage and Trading Revenue |  | 0 | 0
Gain (Loss) on Derivatives, Net |  | $ 18,420 | $ 4,667
[1] | Represents changes in fair value of to-be-announced securities and other derivative instruments held to mitigate market risk of trading securities portfolio, which is offset by changes in fair value of trading securities also include in Brokerage and Trading Revenue in the Consolidated Statements of Earnings.

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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- Definition Amount of gain (loss) resulting from the difference between the acquisition price and the selling price or fair value of trading assets and trading liabilities, conducted separately from customer trading activities. Includes, but is not limited to, changes in fair value of trading assets and trading liabilities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4F -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624186-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -Section 35 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=35711043&loc=d3e42454-110968 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 940 -SubTopic 320 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42567-110969 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13(e)) -URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260 + Details
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