INVESTMENTS (Schedule of Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Available-for-sale, Amortized Cost
Due in one year or less	$ 1,002
Due after one year through five years	13,612
Due after five years through ten years	60,206
Due after ten years	0
Subtotal	74,820
Mortgage-related securities	702,801
Available-for-sale securities, book value	777,621	$ 796,960
Available-for-sale, Fair Value
Due in one year or less	1,003
Due after one year through five years	12,323
Due after five years through ten years	59,032
Due after ten years	0
Subtotal	72,358
Mortgage-related securities	614,065
Fair value, total	$ 686,423	$ 695,875