COMPREHENSIVE INCOME (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Before Tax Amount [Abstract]
Other comprehensive (loss) income, before tax	$ (97)		$ 7,485		$ (49,826)		$ 13,317
Tax Effect [Abstract]
Other comprehensive (loss) income, tax effect	41		(2,867)		19,083		(5,104)
Net of Tax Amount [Abstract]
Other comprehensive (loss) income, net of tax	(56)		4,618		(30,743)		8,213
Net income (loss)	24,857		23,825		66,417		67,315
Comprehensive income	24,801		28,443		35,674		75,528
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Before Tax Amount [Abstract]
Other comprehensive loss before reclassifications, before tax	(1,439)		6,820		(53,820)		10,519
Tax Effect [Abstract]
Unrealized losses arising during holding period, tax effect	554		(2,613)		20,610		(4,034)
Net of Tax Amount [Abstract]
Other Comprehensive Loss Before Reclassification Adjustments, Net Of Tax	(885)		4,207		(33,210)		6,485
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Amounts reclassified from accumulated other comprehensive income [Member]
Before Tax Amount [Abstract]
Amounts reclassified from accumulated OCI, before tax	5	[1]	(39)	[1]	(17)	[1]	(290)	[1]
Tax Effect [Abstract]
Reclassification adjustment for net gains realized in net income, tax effect	(1)	[1]	15	[1]	7	[1]	111	[1]
Net of Tax Amount [Abstract]
Amounts reclassified from accumulated OCI, net of tax	4	[1]	(24)	[1]	(10)	[1]	(179)	[1]
Accumulated Defined Benefit Plans Adjustment [Member]
Before Tax Amount [Abstract]
Other comprehensive loss before reclassifications, before tax	1,337	[2]	704	[2]	4,011	[2]	3,088	[2]
Tax Effect [Abstract]
Recognized employee benefit plan net periodic benefit cost, tax effect	(512)	[2]	(269)	[2]	(1,534)	[2]	(1,181)	[2]
Net of Tax Amount [Abstract]
Other Comprehensive Loss Before Reclassification Adjustments, Net Of Tax	$ 825	[2]	$ 435	[2]	$ 2,477	[2]	$ 1,907	[2]

[1] Reclassification adjustments for net gains (losses) on available-for-sale securities are reported as net security gains (losses) on the consolidated statements of income.

[2] Recognized employee benefit plan net periodic benefit cost include amortization of unrecognized transition amount, recognized prior service cost and recognized net loss. For more information, see Note 9 - Pension Benefits.