SECURITIES - Weighted Average Life (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Estimated Fair Value
Total	$ 91,338,611	$ 92,563,572
Amortized Cost
Total	95,408,711	93,803,739
Residential Investments
Estimated Fair Value
Less than one year	19,335	471,977
Greater than one year through five years	10,442,022	13,838,890
Greater than five years through ten years	79,260,878	77,273,833
Greater than ten years	1,429,881	716,121
Total	91,152,116	92,300,821
Amortized Cost
Less than one year	19,339	476,538
Greater than one year through five years	10,737,675	13,925,749
Greater than five years through ten years	83,003,720	78,431,852
Greater than ten years	1,461,134	708,363
Total	$ 95,221,868	$ 93,542,502