BORROWINGS (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Debt Disclosure [Abstract]
Balance outstanding at end of year, amount	$ 328,604	$ 356,219	$ 316,163
Balance outstanding at end of year, weighted average interest rate	0.30%	0.58%	0.84%
Average daily balance outstanding	334,167	357,168	341,447
Average daily balance outstanding, weighted average interest rate	0.35%	0.66%	1.54%
Maximum balance outstanding at any month end	$ 358,461	$ 392,323	$ 361,060