SECURITIES AVAILABLE FOR SALE, HELD TO MATURITY, AND MARKETABLE EQUITY SECURITIES - Schedule of Maturity of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Available for sale, Amortized Cost
Within 1 year	$ 38,196
Over 1 year to 5 years	12,714
Over 5 years to 10 years	75,351
Over 10 years	98,517
Total bonds and obligations	224,778
Mortgage-backed securities	1,307,782
Amortized  Cost	1,532,560	$ 1,297,339
Available for sale, Fair Value
Within 1 year	38,234
Over 1 year to 5 years	12,610
Over 5 years to 10 years	76,403
Over 10 years	106,948
Total bonds and obligations	234,195
Mortgage-backed securities	1,341,094
Fair Value	1,575,289	1,311,555
Held to maturity, Amortized Cost
Within 1 year	2,526
Over 1 year to 5 years	4,006
Over 5 years to 10 years	23,066
Over 10 years	216,890
Total bonds and obligations	246,488
Mortgage-backed securities	83,709
Amortized  Cost	330,197	357,979
Held to maturity, Fair Value
Within 1 year	2,528
Over 1 year to 5 years	4,022
Over 5 years to 10 years	23,897
Over 10 years	234,465
Total bonds and obligations	264,912
Mortgage-backed securities	91,123
Fair Value	$ 356,035	$ 373,277