MARKETABLE SECURITIES - Securities in Continuous Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Gross Unrealized Losses
Less Than 12 Months	$ (945)	$ (2,483)
12 Months or Longer	(484)	(790)
Total	(1,429)	(3,273)
Estimated Fair Value
Less Than 12 Months	111,555	129,603
12 Months or Longer	22,518	24,319
Total	134,073	153,922
Gross Unrealized Losses
Less Than 12 Months	(499)	(4,179)
12 Months or Longer	(631)	(521)
Total	(1,130)	(4,700)
Estimated Fair Value
Less Than 12 Months	49,596	118,926
12 Months or Longer	8,312	2,350
Total	57,908	121,276
Corporate bonds
Gross Unrealized Losses
Less Than 12 Months	(8)	(377)
12 Months or Longer	0	0
Total	(8)	(377)
Estimated Fair Value
Less Than 12 Months	2,981	22,529
12 Months or Longer	0	0
Total	2,981	22,529
Municipal securities
Gross Unrealized Losses
Less Than 12 Months	(300)	(622)
12 Months or Longer	0	0
Total	(300)	(622)
Estimated Fair Value
Less Than 12 Months	7,493	7,219
12 Months or Longer	0	0
Total	7,493	7,219
Mortgage-backed securities
Gross Unrealized Losses
Less Than 12 Months	(569)	(1,047)
12 Months or Longer	(333)	(561)
Total	(902)	(1,608)
Estimated Fair Value
Less Than 12 Months	75,674	44,420
12 Months or Longer	14,375	15,270
Total	90,049	59,690
Collateralized mortgage obligations
Gross Unrealized Losses
Less Than 12 Months	(68)	(437)
12 Months or Longer	(151)	(229)
Total	(219)	(666)
Estimated Fair Value
Less Than 12 Months	25,407	55,435
12 Months or Longer	8,143	9,049
Total	33,550	64,484
Municipal securities
Gross Unrealized Losses
Less Than 12 Months	(406)	(3,889)
12 Months or Longer	(124)	0
Total	(530)	(3,889)
Estimated Fair Value
Less Than 12 Months	38,442	98,943
12 Months or Longer	6,015	0
Total	44,457	98,943
Mortgage-backed securities
Gross Unrealized Losses
Less Than 12 Months	(93)	(290)
12 Months or Longer	0	0
Total	(93)	(290)
Estimated Fair Value
Less Than 12 Months	11,154	19,983
12 Months or Longer	0	0
Total	11,154	19,983
Collateralized mortgage obligations
Gross Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	(507)	(521)
Total	(507)	(521)
Estimated Fair Value
Less Than 12 Months	0	0
12 Months or Longer	2,297	2,350
Total	$ 2,297	$ 2,350