SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	$ 1,071,974	$ 675,474
Gross Unrealized Gains	27,050	11,701
Gross Unrealized (Losses)	(3,388)	(9,827)
Total securities available for sale, Estimated Fair Value	1,095,636	677,348
US Government Agencies Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	1,328	1,654
Gross Unrealized Gains	603	499
Gross Unrealized (Losses)
Total securities available for sale, Estimated Fair Value	1,931	2,153
Obligations of States and Political Subdivisions [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	419,525	255,335
Gross Unrealized Gains	17,545	6,107
Gross Unrealized (Losses)	(1,413)	(6,612)
Total securities available for sale, Estimated Fair Value	435,657	254,830
Corporate and Other Bonds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	79,069	9,479
Gross Unrealized Gains	264	115
Gross Unrealized (Losses)	(434)	(160)
Total securities available for sale, Estimated Fair Value	78,899	9,434
Mortgage Backed Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	562,229	405,389
Gross Unrealized Gains	8,605	4,954
Gross Unrealized (Losses)	(1,506)	(2,981)
Total securities available for sale, Estimated Fair Value	569,328	407,362
Other Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Amortized Cost	9,823	3,617
Gross Unrealized Gains	33	26
Gross Unrealized (Losses)	(35)	(74)
Total securities available for sale, Estimated Fair Value	$ 9,821	$ 3,569