Quarterly report pursuant to Section 13 or 15(d)

SECURITIES (Schedule of Gross Unrealized Losses and Fair Value of Investments) (Details)

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SECURITIES (Schedule of Gross Unrealized Losses and Fair Value of Investments) (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value $ 796,844 $ 335,205
Less than 12 months, Unrealized Losses (14,881) (3,498)
More than 12 Months, Fair Value 182,813 197,640
More than 12 months, Unrealized Losses (6,334) (4,188)
Total, Fair Value 979,657 532,845
Total, Unrealized Losses (21,215) (7,686)
Obligations of States and Political Subdivisions    
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value 150,377 25,790
Less than 12 months, Unrealized Losses (2,128) (132)
More than 12 Months, Fair Value 6,444 16,934
More than 12 months, Unrealized Losses (251) (432)
Total, Fair Value 156,821 42,724
Total, Unrealized Losses (2,379) (564)
Mortgage-Backed Securities    
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value 598,640 298,439
Less than 12 months, Unrealized Losses (12,356) (3,267)
More than 12 Months, Fair Value 141,647 136,298
More than 12 months, Unrealized Losses (5,156) (2,902)
Total, Fair Value 740,287 434,737
Total, Unrealized Losses (17,512) (6,169)
Corporate and Other Bonds    
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value 47,827 10,976
Less than 12 months, Unrealized Losses (397) (99)
More than 12 Months, Fair Value 34,722 44,408
More than 12 months, Unrealized Losses (927) (854)
Total, Fair Value 82,549 55,384
Total, Unrealized Losses $ (1,324) $ (953)