PARENT COMPANY FINANCIALS ONLY (Details 1) - USD ($)		3 Months Ended								12 Months Ended
		Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Derivative Asset		$ 17,318,000				$ 22,331,000				$ 17,318,000	$ 22,331,000
Income
Dividends received from subsidiaries(1)										46,900,000	44,500,000
Expenses
Interest expense		5,044,000	$ 4,705,000	$ 4,378,000	$ 4,207,000	4,676,000	$ 4,640,000	$ 4,627,000	$ 4,850,000	18,334,000	18,793,000	$ 20,617,000
Income tax benefit		14,915,000	12,681,000	10,731,000	9,014,000	7,698,000	9,793,000	9,508,000	8,428,000	47,341,000	35,427,000	27,218,000
Net Income		22,064,000	$ 23,852,000	$ 20,563,000	$ 20,725,000	17,179,000	$ 20,484,000	$ 20,374,000	$ 18,611,000	87,204,000	76,648,000	64,960,000
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Dividend Income, Operating	[1]									47,006,000	44,598,000	38,153,000
Derivative Asset	[2]	$ 1,535,000				$ 1,364,000				1,535,000	1,364,000
Income
Interest income(2)	[3]									50,000	98,000	78,000
Total income										47,056,000	44,696,000	38,231,000
Expenses
Interest expense										3,995,000	5,901,000	5,769,000
Other expenses												29,000
Total expenses										3,995,000	5,901,000	5,798,000
Income before income taxes and equity in undistributed income of subsidiaries										43,061,000	38,795,000	32,433,000
Income tax benefit										(1,523,000)	(1,791,000)	(2,301,000)
Income of parent company										44,584,000	40,586,000	34,734,000
Equity in undistributed income of subsidiaries										42,620,000	36,062,000	30,226,000
Net Income										87,204,000	76,648,000	64,960,000
Consolidation, Eliminations [Member]
Income
Dividends received from subsidiaries(1)										$ 67,000	$ 62,000	$ 55,000

[1] Income of $67,000, $62,000 and $55,000 was not eliminated in consolidation for the years ended December 31, 2017, 2016, and 2015, respectively.

[2] Entire balance eliminates in consolidation.

[3] Entire balance eliminated in consolidation.