Trading Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Trading Securities [Line Items]
Trading securities	$ 4,707,975	$ 1,623,921
Trading Securities, Net Unrealized Gain (Loss)	(3,560)	2,359
U.S. government securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	9,183	44,264
Trading Securities, Net Unrealized Gain (Loss)	0	6
Residential agency mortgage-backed securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	4,669,148	1,504,651
Trading Securities, Net Unrealized Gain (Loss)	(3,624)	2,293
Municipal securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	19,172	26,196
Trading Securities, Net Unrealized Gain (Loss)	42	60
Asset-backed securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	0	14,084
Trading Securities, Net Unrealized Gain (Loss)	0	(21)
Other debt securities [Member]
Schedule of Trading Securities [Line Items]
Trading securities	10,472	34,726
Trading Securities, Net Unrealized Gain (Loss)	$ 22	$ 21