COMPREHENSIVE INCOME (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net unrealized gains on available-for- sale securities, before tax amount [Abstract]
Unrealized losses arising during holding period, before tax amount	$ (4,706)	$ (4,044)
Reclassification adjustment for net gains realized in net income, before tax amount	(74)	(17)
Recognized employee benefit plan net periodic benefit cost, before tax amount	1,192	633
Other comprehensive loss	(3,588)	(3,428)
Net unrealized gains on available-for- sale securities, tax (expense) benefit [Abstract]
Unrealized losses arising during holding period, tax (expense) benefit	1,799	1,537
Reclassification adjustment for net gains realized in net income, tax (expense) benefit	28	7
Recognized employee benefit plan net periodic benefit cost, tax (expense) benefit	(114)	(242)
Other comprehensive loss	1,713	1,302
Net unrealized gains on available-for- sale securities, net of tax amount [Abstract]
Unrealized losses arising during holding period, net of tax amount	(2,907)	(2,507)
Reclassification adjustment for net gains realized in net income, net of tax amount	(46)	(10)
Recognized employee benefit plan net periodic benefit cost, net of tax amount	1,078	391
Other comprehensive loss	(1,875)	(2,126)
Net income (loss)	22,866	(494)
Comprehensive income (loss)	$ 20,991	$ (2,620)