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
Sep. 30, 2018
Dec. 31, 2017
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value $ 1,261,174 $ 335,205
Less than 12 months, Unrealized Losses (20,874) (3,498)
More than 12 Months, Fair Value 292,110 197,640
More than 12 months, Unrealized Losses (11,787) (4,188)
Total, Fair Value 1,553,284 532,845
Total, Unrealized Losses (32,661) (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 377,882 25,790
Less than 12 months, Unrealized Losses (5,814) (132)
More than 12 Months, Fair Value 7,674 16,934
More than 12 months, Unrealized Losses (361) (432)
Total, Fair Value 385,556 42,724
Total, Unrealized Losses (6,175) (564)
Mortgage-Backed Securities    
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value 794,067 298,439
Less than 12 months, Unrealized Losses (14,057) (3,267)
More than 12 Months, Fair Value 245,879 136,298
More than 12 months, Unrealized Losses (10,237) (2,902)
Total, Fair Value 1,039,946 434,737
Total, Unrealized Losses (24,294) (6,169)
Corporate and Other Bonds    
Schedule of gross unrealized losses and fair value of investments [Line Items]    
Less than 12 months, Fair Value 89,225 10,976
Less than 12 months, Unrealized Losses (1,003) (99)
More than 12 Months, Fair Value 38,557 44,408
More than 12 months, Unrealized Losses (1,189) (854)
Total, Fair Value 127,782 55,384
Total, Unrealized Losses $ (2,192) $ (953)