INVESTMENTS (Schedule of Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Available-for-sale, Amortized Cost
Due in one year or less	$ 1,217
Due after one year through five years	9,227
Due after five years through ten years	63,681
Due after ten years	2,999
Subtotal	77,124
Mortgage-related securities	787,476
Available-for-sale securities, book value	864,600	$ 1,508,981
Available-for-sale, Fair Value
Due in one year or less	1,222
Due after one year through five years	8,762
Due after five years through ten years	62,078
Due after ten years	3,025
Subtotal	75,087
Mortgage-related securities	713,036
Fair value, total	$ 788,123	$ 1,507,486