STOCKHOLDERS' EQUITY (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
STOCKHOLDERS' EQUITY
Number of treasury shares purchased									351,640	63,681	80,173
Weighted average price of treasury shares (in dollars per share)									$ 38.50	$ 23.17	$ 18.27
Reclassification adjustments from accumulated other comprehensive income
Gain on sale of securities	$ (272)			$ 409	$ 1,239				$ 137	$ 1,239
Acquisition-related securities gain		5,222							5,222
Total before tax	12,582	35,383	6,302	21,213	32,468	26,937	25,970	8,121	75,480	93,496	87,504
Income tax expense	(9,135)	(11,243)	(1,906)	(7,719)	(12,576)	(10,849)	(10,413)	(2,857)	(30,003)	(36,695)	(36,800)
NET EARNINGS	3,109	24,163	4,349	13,494	19,892	16,088	15,557	5,264	45,115	56,801	50,704
Unrealized gains (losses) on available-for-sale securities | Amount Reclassified from AOCI
Reclassification adjustments from accumulated other comprehensive income
Gain on sale of securities									137
Acquisition-related securities gain									5,222
Total before tax									5,359
Income tax expense									(58)
NET EARNINGS									$ 5,301