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Derivatives, Fair Value of Derivatives Contracts (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017 | Jun. 30, 2017
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Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derviative contracts, net of cash collateral, Assets, Fair value | $ 373,373 |  | $ 220,502 |  | $ 280,289 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 234,856 |  | 171,963 |  | 285,819 |
Not Designated as Hedging Instrument [Member] |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 28,203,682 | [1] | 20,038,522 | [2] | 29,511,796 | [3]
Derivative Liabilities, Notional | 29,551,215 | [1] | 20,186,467 | [2] | 27,125,429 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 486,962 |  | 301,052 |  | 355,296 |
Derivative Assets, Netting Adjustments | (100,160) |  | (74,022) |  | (50,607) |
Derivative Assets, Net Fair Value Before Cash Collateral | 386,802 |  | 227,030 |  | 304,689 |
Derivative Assets, Cash Collateral | (13,428) |  | (6,528) |  | (24,400) |
Derviative contracts, net of cash collateral, Assets, Fair value | 373,374 |  | 220,502 |  | 280,289 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 484,768 |  | 302,405 |  | 357,521 |
Derivative Liabilities, Netting Adjustments | (100,160) |  | (74,022) |  | (50,607) |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 384,608 |  | 228,383 |  | 306,914 |
Derivative Liabilities, Cash Collateral | (149,752) |  | (56,420) |  | (21,095) |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 234,856 |  | 171,963 |  | 285,819 |
Not Designated as Hedging Instrument [Member] | To-be-announced residential mortgage-backed securities |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 15,027,678 | [1] | 12,347,542 | [2] | 16,174,687 | [3]
Derivative Liabilities, Notional | 14,443,478 | [1] | 11,537,742 | [2] | 16,174,687 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 52,681 |  | 23,606 |  | 57,948 |
Derivative Assets, Netting Adjustments | (17,382) |  | (18,096) |  | (29,034) |
Derivative Assets, Net Fair Value Before Cash Collateral | 35,299 |  | 5,510 |  | 28,914 |
Derivative Assets, Cash Collateral | 0 |  | 0 |  | 0 |
Derviative contracts, net of cash collateral, Assets, Fair value | 35,299 |  | 5,510 |  | 28,914 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 49,343 |  | 20,367 |  | 53,829 |
Derivative Liabilities, Netting Adjustments | (17,382) |  | (18,096) |  | (29,034) |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 31,961 |  | 2,271 |  | 24,795 |
Derivative Liabilities, Cash Collateral | (31,808) |  | (704) |  | 0 |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 153 |  | 1,567 |  | 24,795 |
Not Designated as Hedging Instrument [Member] | Interest rate swaps |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 1,745,237 | [1] | 1,478,944 | [2] | 1,450,193 | [3]
Derivative Liabilities, Notional | 1,745,237 | [1] | 1,478,944 | [2] | 1,450,193 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 43,040 |  | 28,278 |  | 29,932 |
Derivative Assets, Netting Adjustments | (2,193) |  | 0 |  | 0 |
Derivative Assets, Net Fair Value Before Cash Collateral | 40,847 |  | 28,278 |  | 29,932 |
Derivative Assets, Cash Collateral | (11,737) |  | (4,964) |  | (2,206) |
Derviative contracts, net of cash collateral, Assets, Fair value | 29,110 |  | 23,314 |  | 27,726 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 43,043 |  | 28,298 |  | 29,982 |
Derivative Liabilities, Netting Adjustments | (2,193) |  | 0 |  | 0 |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 40,850 |  | 28,298 |  | 29,982 |
Derivative Liabilities, Cash Collateral | (4,946) |  | (12,896) |  | (15,396) |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 35,904 |  | 15,402 |  | 14,586 |
Not Designated as Hedging Instrument [Member] | Energy contracts |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 1,465,826 | [1] | 1,190,067 | [2] | 891,480 | [3]
Derivative Liabilities, Notional | 1,434,980 | [1] | 1,166,924 | [2] | 874,625 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 200,640 |  | 103,044 |  | 56,824 |
Derivative Assets, Netting Adjustments | (69,991) |  | (47,873) |  | (20,546) |
Derivative Assets, Net Fair Value Before Cash Collateral | 130,649 |  | 55,171 |  | 36,278 |
Derivative Assets, Cash Collateral | 0 |  | (196) |  | (21,267) |
Derviative contracts, net of cash collateral, Assets, Fair value | 130,649 |  | 54,975 |  | 15,011 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 199,119 |  | 101,603 |  | 53,895 |
Derivative Liabilities, Netting Adjustments | (69,990) |  | (47,873) |  | (20,546) |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 129,129 |  | 53,730 |  | 33,349 |
Derivative Liabilities, Cash Collateral | (112,481) |  | (42,767) |  | 0 |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 16,648 |  | 10,963 |  | 33,349 |
Not Designated as Hedging Instrument [Member] | Agricultural contracts |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 23,508 | [1] | 53,238 | [2] | 45,250 | [3]
Derivative Liabilities, Notional | 23,496 | [1] | 48,552 | [2] | 45,262 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 1,164 |  | 1,576 |  | 3,541 |
Derivative Assets, Netting Adjustments | (181) |  | (960) |  | (1,027) |
Derivative Assets, Net Fair Value Before Cash Collateral | 983 |  | 616 |  | 2,514 |
Derivative Assets, Cash Collateral | (741) |  | 0 |  | 0 |
Derviative contracts, net of cash collateral, Assets, Fair value | 242 |  | 616 |  | 2,514 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 1,142 |  | 1,551 |  | 3,538 |
Derivative Liabilities, Netting Adjustments | (181) |  | (960) |  | (1,027) |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 961 |  | 591 |  | 2,511 |
Derivative Liabilities, Cash Collateral | 0 |  | 0 |  | (2,511) |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 961 |  | 591 |  | 0 |
Not Designated as Hedging Instrument [Member] | Foreign exchange contracts |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 174,851 | [1] | 132,397 | [2] | 169,529 | [3]
Derivative Liabilities, Notional | 161,567 | [1] | 126,251 | [2] | 169,553 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 170,556 |  | 129,551 |  | 162,429 |
Derivative Assets, Netting Adjustments | 0 |  | 0 |  | 0 |
Derivative Assets, Net Fair Value Before Cash Collateral | 170,556 |  | 129,551 |  | 162,429 |
Derivative Assets, Cash Collateral | (290) |  | (448) |  | (7) |
Derviative contracts, net of cash collateral, Assets, Fair value | 170,266 |  | 129,103 |  | 162,422 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 157,174 |  | 123,321 |  | 162,276 |
Derivative Liabilities, Netting Adjustments | (1) |  | 0 |  | 0 |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 157,173 |  | 123,321 |  | 162,276 |
Derivative Liabilities, Cash Collateral | (517) |  | (53) |  | (3,188) |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 156,656 |  | 123,268 |  | 159,088 |
Not Designated as Hedging Instrument [Member] | Equity option contracts |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 93,943 | [1] | 99,633 | [2] | 100,159 | [3]
Derivative Liabilities, Notional | 93,943 | [1] | 99,633 | [2] | 100,159 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 4,121 |  | 5,503 |  | 4,437 |
Derivative Assets, Netting Adjustments | 0 |  | 0 |  | 0 |
Derivative Assets, Net Fair Value Before Cash Collateral | 4,121 |  | 5,503 |  | 4,437 |
Derivative Assets, Cash Collateral | (660) |  | (920) |  | (920) |
Derviative contracts, net of cash collateral, Assets, Fair value | 3,461 |  | 4,583 |  | 3,517 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 4,121 |  | 5,503 |  | 4,437 |
Derivative Liabilities, Netting Adjustments | 0 |  | 0 |  | 0 |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 4,121 |  | 5,503 |  | 4,437 |
Derivative Liabilities, Cash Collateral | 0 |  | 0 |  | 0 |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 4,121 |  | 5,503 |  | 4,437 |
Not Designated as Hedging Instrument [Member] | Total customer risk management programs |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 18,531,043 | [1] | 15,301,821 | [2] | 18,831,298 | [3]
Derivative Liabilities, Notional | 17,902,701 | [1] | 14,458,046 | [2] | 18,814,479 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 472,202 |  | 291,558 |  | 315,111 |
Derivative Assets, Netting Adjustments | (89,747) |  | (66,929) |  | (50,607) |
Derivative Assets, Net Fair Value Before Cash Collateral | 382,455 |  | 224,629 |  | 264,504 |
Derivative Assets, Cash Collateral | (13,428) |  | (6,528) |  | (24,400) |
Derviative contracts, net of cash collateral, Assets, Fair value | 369,027 |  | 218,101 |  | 240,104 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 453,942 |  | 280,643 |  | 307,957 |
Derivative Liabilities, Netting Adjustments | (89,747) |  | (66,929) |  | (50,607) |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 364,195 |  | 213,714 |  | 257,350 |
Derivative Liabilities, Cash Collateral | (149,752) |  | (56,420) |  | (21,095) |
Derivative Liabilities, Fair Value, Net of Cash Collateral | 214,443 |  | 157,294 |  | 236,255 |
Not Designated as Hedging Instrument [Member] | Internal risk management programs |  |  |  |  |  |
Notional Amount of Derivatives [Abstract] |  |  |  |  |  |
Derivative Assets, Notional | 9,672,639 | [1] | 4,736,701 | [2] | 10,680,498 | [3]
Derivative Liabilities, Notional | 11,648,514 | [1] | 5,728,421 | [2] | 8,310,950 | [3]
Derivative Assets, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Assets, Gross Fair Value | 14,760 |  | 9,494 |  | 40,185 |
Derivative Assets, Netting Adjustments | (10,413) |  | (7,093) |  | 0 |
Derivative Assets, Net Fair Value Before Cash Collateral | 4,347 |  | 2,401 |  | 40,185 |
Derivative Assets, Cash Collateral | 0 |  | 0 |  | 0 |
Derviative contracts, net of cash collateral, Assets, Fair value | 4,347 |  | 2,401 |  | 40,185 |
Derivative Liabilities, Fair Value, Net [Abstract] |  |  |  |  |  |
Derivative Liabilities, Gross Fair Value | 30,826 |  | 21,762 |  | 49,564 |
Derivative Liabilities, Netting Adjustments | (10,413) |  | (7,093) |  | 0 |
Derivative Liabilities, Net Fair Value Before Cash Collateral | 20,413 |  | 14,669 |  | 49,564 |
Derivative Liabilities, Cash Collateral | 0 |  | 0 |  | 0 |
Derivative Liabilities, Fair Value, Net of Cash Collateral | $ 20,413 |  | $ 14,669 |  | $ 49,564 |
[1] | Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.
[2] | Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.
[3] | Notional amounts for commodity contracts are converted into dollar-equivalent amounts based on dollar prices at the inception of the contract.

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- Definition Represents net derivative liability before consideration of right to reclasim cash collateral under master netting or similar arrangements. + References No definition available. + 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://www.xbrl.org/2003/role/presentationRef -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/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13495-108611 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313 + Details
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