SECURITIES - Schedule of Unrealized Loss and Fair Value on Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Fair Value
Less than 12 months	$ 499,646	$ 664,476
12 months or longer	274,477	198,397
Total	774,123	862,873
Unrealized Losses
Less than 12 months	(9,255)	(13,451)
12 months or longer	(5,841)	(4,992)
Total	(15,096)	(18,443)
Collateralized Loan Obligations [Member]
Fair Value
Less than 12 months	0	8,152
12 months or longer	18,207	51,694
Total	18,207	59,846
Unrealized Losses
Less than 12 months	0	(41)
12 months or longer	(97)	(938)
Total	(97)	(979)
Mortgage-backed securities of U.S. Government Sponsored Entities [Member]
Fair Value
Less than 12 months	275,646	327,759
12 months or longer	41,533	5,387
Total	317,179	333,146
Unrealized Losses
Less than 12 months	(4,550)	(5,991)
12 months or longer	(629)	(75)
Total	(5,179)	(6,066)
Collateralized Mortgage Obligations Of US Government Sponsored Entities [Member]
Fair Value
Less than 12 months	159,951	234,175
12 months or longer	124,465	58,912
Total	284,416	293,087
Unrealized Losses
Less than 12 months	(3,315)	(5,599)
12 months or longer	(3,504)	(2,096)
Total	(6,819)	(7,695)
Private mortgage backed securities [Member]
Fair Value
Less than 12 months	0	0
12 months or longer	36,879	36,848
Total	36,879	36,848
Unrealized Losses
Less than 12 months	0	0
12 months or longer	(737)	(900)
Total	(737)	(900)
Private collateralized mortgage obligations [Member]
Fair Value
Less than 12 months	1,721	1,460
12 months or longer	33,735	38,417
Total	35,456	39,877
Unrealized Losses
Less than 12 months	(5)	0
12 months or longer	(642)	(816)
Total	(647)	(816)
Obligations of state and political subdivisions [Member]
Fair Value
Less than 12 months	28,536	39,321
12 months or longer	10,774	0
Total	39,310	39,321
Unrealized Losses
Less than 12 months	(718)	(895)
12 months or longer	(142)	0
Total	(860)	(895)
Corporate and other debt securities [member]
Fair Value
Less than 12 months	13,763	33,008
12 months or longer	4,828	0
Total	18,591	33,008
Unrealized Losses
Less than 12 months	(332)	(517)
12 months or longer	(9)	0
Total	(341)	(517)
Commercial mortgage backed securities [Member]
Fair Value
Less than 12 months	12,041	12,667
12 months or longer	4,056	7,139
Total	16,097	19,806
Unrealized Losses
Less than 12 months	(291)	(306)
12 months or longer	(81)	(167)
Total	(372)	(473)
Commercial mortgage backed securities of U.S. Government Sponsored Entities [Member]
Fair Value
Less than 12 months	7,988	7,934
12 months or longer	0	0
Total	7,988	7,934
Unrealized Losses
Less than 12 months	(44)	(102)
12 months or longer	0	0
Total	$ (44)	$ (102)