MARKETABLE SECURITIES - Contractual Maturities of Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Amortized Cost
Due within one year	$ 0
Due after one year through five years	17,279
Due after five years through ten years	27,250
Due after ten years	0
Available-for-sale debt securities, amortized cost basis	213,913	$ 341,628
Estimated Fair Value
Due within one year	0
Due after one year through five years	16,826
Due after five years through ten years	26,196
Due after ten years	0
Available-for-sale debt securities, estimated fair value	196,095	342,206
Held to Maturity Amortized Cost
Due within one year	276,151
Due after one year through five years	162,627
Due after five years through ten years	62,262
Due after ten years	28,798
Held to Maturity debt securities, amortized cost	713,390	184,263
Held to Maturity Estimated Fair Value
Due within one year	274,879
Due after one year through five years	160,856
Due after five years through ten years	58,025
Due after ten years	24,137
Held to maturity debt securities, estimated fair value	682,497	192,472
Mortgage-backed securities
Amortized Cost
Available-for-sale debt securities, amortized cost basis	144,128
Available-for-sale debt securities, amortized cost basis	144,128	221,610
Estimated Fair Value
Available-for-sale debt securities, estimated fair value	129,184
Available-for-sale debt securities, estimated fair value	129,184	221,308
Held to Maturity Amortized Cost
Held to Maturity debt securities, amortized cost	138,802
Held to Maturity debt securities, amortized cost	138,802	2,953
Held to Maturity Estimated Fair Value
Held to maturity debt securities, estimated fair value	125,997
Held to maturity debt securities, estimated fair value	125,997	2,916
Collateralized mortgage obligations
Amortized Cost
Available-for-sale debt securities, amortized cost basis	25,256
Available-for-sale debt securities, amortized cost basis	25,256	74,925
Estimated Fair Value
Available-for-sale debt securities, estimated fair value	23,889
Available-for-sale debt securities, estimated fair value	23,889	$ 74,992
Held to Maturity Amortized Cost
Held to Maturity debt securities, amortized cost	44,750
Held to Maturity debt securities, amortized cost	44,750
Held to Maturity Estimated Fair Value
Held to maturity debt securities, estimated fair value	38,603
Held to maturity debt securities, estimated fair value	$ 38,603