Investment In Securities - Weighted Average Lives of Trading Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value
1 year	$ 0	$ 98,646
≥ 1 year and 3 years	389,883	0
≥ 3 years and 5 years	407,656	201,811
≥ 5 years	86,062	638,727
Total	883,601	939,184
Amortized Cost
1 year	0	98,703
≥ 1 year and 3 years	369,600	0
≥ 3 years and 5 years	375,030	183,025
≥ 5 years	80,214	574,004
Total	824,844	855,732
Credit Risk and Non-Agency Securities
Fair Value
Total	883,601	819,915	$ 975,830
Amortized Cost
Total	$ 824,844	$ 736,831