SECURITIES (Securities with Continuous Loss Position) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available-for-Sale:
Less than 12 Months, Fair Value	$ 412,162	$ 617,847
Less than 12 Months, Unrealized Losses	(4,313)	(5,686)
12 Months or More, Fair Value	659,936	151,971
12 Months or More, Unrealized Losses	(15,056)	(2,877)
Total Fair Value	1,072,098	769,818
Total Unrealized Losses	(19,369)	(8,563)
Held-to-Maturity:
Less Than 12 Months, Fair Value	40,804	59,862
Less Than 12 Months, Unrealized Losses	(495)	(549)
12 Months or More, Fair Value	75,159	38,748
12 Months or More, Unrealized Losses	(2,995)	(1,221)
Total Fair Value	115,963	98,610
Total Unrealized Losses	(3,490)	(1,770)
U.S. Government and agency obligations
Available-for-Sale:
Less than 12 Months, Fair Value	75,885	31,276
Less than 12 Months, Unrealized Losses	(1,240)	(211)
12 Months or More, Fair Value	50,508	23,341
12 Months or More, Unrealized Losses	(809)	(220)
Total Fair Value	126,393	54,617
Total Unrealized Losses	(2,049)	(431)
Held-to-Maturity:
Less Than 12 Months, Fair Value	145
Less Than 12 Months, Unrealized Losses	(1)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Total Fair Value	145
Total Unrealized Losses	(1)
Municipal bonds
Available-for-Sale:
Less than 12 Months, Fair Value	6,422	20,879
Less than 12 Months, Unrealized Losses	(54)	(185)
12 Months or More, Fair Value	27,231	13,360
12 Months or More, Unrealized Losses	(478)	(260)
Total Fair Value	33,653	34,239
Total Unrealized Losses	(532)	(445)
Held-to-Maturity:
Less Than 12 Months, Fair Value	29,898	21,839
Less Than 12 Months, Unrealized Losses	(274)	(171)
12 Months or More, Fair Value	44,637	34,314
12 Months or More, Unrealized Losses	(2,304)	(1,081)
Total Fair Value	74,535	56,153
Total Unrealized Losses	(2,578)	(1,252)
Corporate bonds
Available-for-Sale:
Less than 12 Months, Fair Value	3,199	296
Less than 12 Months, Unrealized Losses	(56)	(4)
12 Months or More, Fair Value	295	4,682
12 Months or More, Unrealized Losses	(5)	(40)
Total Fair Value	3,494	4,978
Total Unrealized Losses	(61)	(44)
Held-to-Maturity:
Less Than 12 Months, Fair Value	0
Less Than 12 Months, Unrealized Losses	0
12 Months or More, Fair Value	487
12 Months or More, Unrealized Losses	(13)
Total Fair Value	487
Total Unrealized Losses	(13)
Mortgage-backed or related securities
Available-for-Sale:
Less than 12 Months, Fair Value	316,074	559,916
Less than 12 Months, Unrealized Losses	(2,939)	(5,138)
12 Months or More, Fair Value	571,989	100,662
12 Months or More, Unrealized Losses	(13,668)	(2,264)
Total Fair Value	888,063	660,578
Total Unrealized Losses	(16,607)	(7,402)
Held-to-Maturity:
Less Than 12 Months, Fair Value	10,761	38,023
Less Than 12 Months, Unrealized Losses	(220)	(378)
12 Months or More, Fair Value	30,035	4,434
12 Months or More, Unrealized Losses	(678)	(140)
Total Fair Value	40,796	42,457
Total Unrealized Losses	(898)	(518)
Asset-backed securities
Available-for-Sale:
Less than 12 Months, Fair Value	10,582	0
Less than 12 Months, Unrealized Losses	(24)	0
12 Months or More, Fair Value	9,913	9,926
12 Months or More, Unrealized Losses	(96)	(93)
Total Fair Value	20,495	9,926
Total Unrealized Losses	$ (120)	(93)
Equity Securities
Available-for-Sale:
Less than 12 Months, Fair Value		5,480
Less than 12 Months, Unrealized Losses		(148)
12 Months or More, Fair Value		0
12 Months or More, Unrealized Losses		0
Total Fair Value		5,480
Total Unrealized Losses		$ (148)