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Trading Securities (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Schedule of Trading Securities [Line Items] |  |
Trading securities | $ 1,623,921 | $ 1,956,923
Trading Securities, Net Unrealized Gain (Loss) | 2,359 | 10,969
U.S. government agency debentures [Member] |  |
Schedule of Trading Securities [Line Items] |  |
Trading securities | 44,264 | 63,765
Trading Securities, Net Unrealized Gain (Loss) | 6 | 254
Residential agency mortgage-backed securities [Member] |  |
Schedule of Trading Securities [Line Items] |  |
Trading securities | 1,504,651 | 1,791,584
Trading Securities, Net Unrealized Gain (Loss) | 2,293 | 9,966
Municipal and other tax-exempt securities [Member] |  |
Schedule of Trading Securities [Line Items] |  |
Trading securities | 26,196 | 34,507
Trading Securities, Net Unrealized Gain (Loss) | 60 | (1)
Asset-backed securities [Member] |  |
Schedule of Trading Securities [Line Items] |  |
Trading securities | 14,084 | 42,656
Trading Securities, Net Unrealized Gain (Loss) | (21) | 685
Other debt securities [Member] |  |
Schedule of Trading Securities [Line Items] |  |
Trading securities | 34,726 | 24,411
Trading Securities, Net Unrealized Gain (Loss) | $ 21 | $ 65

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