INCOME TAXES ( Summary of Income Tax Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current federal									$ 15,181	$ 15,845	$ 16,346
Deferred federal									988	(1,993)	(5,351)
Current state									877	1,413	1,683
Deferred state									(51)	(677)	(798)
Tax benefit of stock options									187	130	357
Total income tax expense	$ 3,808	$ 4,740	$ 4,392	$ 4,242	$ 3,672	$ 4,418	$ 4,001	$ 2,627	$ 17,182	$ 14,718	$ 12,237