INVESTMENT AND MORTGAGE-BACKED SECURITIES - Sales Information and Marketable Equity Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Sales of Available-for-sale Securities:
Proceeds	$ 138,077	$ 94,252	$ 148,857
Gross gains	1,327	4,592	551
Tax expense on gain	421	1,444	175
Gross losses	120		520
Tax benefit on loss	38		166
Proceeds:
Marketable equity securities	6,101	546	570
Net gain on equity securities	131	361	531
Securities transferred to held-to-maturity	140,399
Sales of securities held-to-maturity	0	0	0
Transfers to or from securities held-to-maturity	$ 0	$ 0	$ 0