INCOME TAXES ( Summary of Income Tax Expense) (Details) - USD ($) $ in Thousands	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
Current federal									$ 27,064	$ 23,749	$ 19,992
Deferred federal									(199)	268	1,378
Revalue deferred taxes due to tax reform									4,137	0	0
Current state									1,559	1,086	1,257
Deferred state									(257)	30	206
Total income tax expense	$ 11,779	$ 7,573	$ 7,394	$ 5,558	$ 6,582	$ 6,498	$ 6,091	$ 5,962	$ 32,304	$ 25,133	$ 22,833