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