MARKETABLE SECURITIES - Contractual Maturities of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost
Due within one year	$ 0
Due after one year through five years	14,633
Due after five years through ten years	30,460
Due after ten years	0
Available-for-sale debt securities, amortized cost basis	341,628	$ 363,097
Estimated Fair Value
Due within one year	0
Due after one year through five years	15,223
Due after five years through ten years	30,683
Due after ten years	0
Available-for-sale debt securities, estimated fair value	342,206	380,795
Held to Maturity Amortized Cost
Due within one year	13,471
Due after one year through five years	57,858
Due after five years through ten years	44,342
Due after ten years	65,639
Held to Maturity debt securities, amortized cost	184,263	0
Held to Maturity Estimated Fair Value
Due within one year	13,578
Due after one year through five years	60,065
Due after five years through ten years	46,491
Due after ten years	69,422
Held to maturity debt securities, estimated fair value	192,472
Mortgage-backed securities
Amortized Cost
Available-for-sale debt securities, amortized cost basis	221,610
Available-for-sale debt securities, amortized cost basis	221,610	104,210
Estimated Fair Value
Available-for-sale debt securities, estimated fair value	221,308
Available-for-sale debt securities, estimated fair value	221,308	107,164
Held to Maturity Amortized Cost
Held to Maturity debt securities, amortized cost	2,953
Held to Maturity debt securities, amortized cost	2,953
Held to Maturity Estimated Fair Value
Held to maturity debt securities, estimated fair value	2,916
Held to maturity debt securities, estimated fair value	2,916
Collateralized mortgage obligations
Amortized Cost
Available-for-sale debt securities, amortized cost basis	74,925
Available-for-sale debt securities, amortized cost basis	74,925	64,611
Estimated Fair Value
Available-for-sale debt securities, estimated fair value	74,992
Available-for-sale debt securities, estimated fair value	74,992	$ 66,945
Held to Maturity Amortized Cost
Held to Maturity debt securities, amortized cost	0
Held to Maturity Estimated Fair Value
Held to maturity debt securities, estimated fair value	$ 0