FAIR VALUES OF FINANCIAL INSTRUMENTS: (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair value measurement
Fair Value	$ 1,364,734	$ 1,020,744
U.S. Government entity mortgage-backed securities
Fair value measurement
Fair Value	120,123	97,814
Mortgage-backed securities, residential
Fair value measurement
Fair Value	626,428	355,121
Mortgage-backed securities, commercial
Fair value measurement
Fair Value	15,671	18,490
Collateralized mortgage obligations
Fair value measurement
Fair Value	175,005	214,160
State and municipal obligations
Fair value measurement
Fair Value	380,098	306,131
Municipal taxable
Fair value measurement
Fair Value	38,626	23,139
U.S. Treasury
Fair value measurement
Fair Value	204	2,753
Collateralized debt obligations
Fair value measurement
Fair Value	3,359	3,136
Other securities
Fair value measurement
Fair Value	5,220
Level 1
Fair value measurement
Fair Value	0	0
Level 2
Fair value measurement
Fair Value	1,357,737	1,015,713
Derivative Assets	1,030	2,465
Derivative Liabilities	(1,030)	(2,465)
Level 2 | U.S. Government entity mortgage-backed securities
Fair value measurement
Fair Value	120,123	97,814
Level 2 | Mortgage-backed securities, residential
Fair value measurement
Fair Value	626,428	355,121
Level 2 | Mortgage-backed securities, commercial
Fair value measurement
Fair Value	15,671	18,490
Level 2 | Collateralized mortgage obligations
Fair value measurement
Fair Value	175,005	214,160
Level 2 | State and municipal obligations
Fair value measurement
Fair Value	378,203	304,236
Level 2 | Municipal taxable
Fair value measurement
Fair Value	38,626	23,139
Level 2 | U.S. Treasury
Fair value measurement
Fair Value	204	2,753
Level 2 | Other securities
Fair value measurement
Fair Value	3,477
Level 3
Fair value measurement
Fair Value	6,997	5,031
Level 3 | State and municipal obligations
Fair value measurement
Fair Value	1,895	1,895
Level 3 | Collateralized debt obligations
Fair value measurement
Fair Value	3,359	$ 3,136
Level 3 | Other securities
Fair value measurement
Fair Value	$ 1,743