COMPREHENSIVE INCOME (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014	Jun. 30, 2013
Before Tax Amount [Abstract]
Other comprehensive (loss) income, before tax	$ 11,376		$ (42,476)		$ 24,180	$ (49,729)
Tax Effect [Abstract]
Other comprehensive (loss) income, tax effect	(4,356)		16,263		(9,261)	19,042
Net of Tax Amount [Abstract]
Other comprehensive (loss) income, net of tax	7,020		(26,213)		14,919	(30,687)
Net income (loss)	30,868		20,755		59,312	41,560
Comprehensive income	37,888		(5,458)		74,231	10,873
Reclassification Adjustment For Net Losses (Gains) Realized In Net Income [Member]
Before Tax Amount [Abstract]
Amounts reclassified from accumulated OCI, before tax	(5)	[1]	(3)	[1]	(1)	(22)
Tax Effect [Abstract]
Reclassification adjustment for net gains realized in net income, tax effect	2	[1]	1	[1]		8
Net of Tax Amount [Abstract]
Amounts reclassified from accumulated OCI, net of tax	(3)	[1]	(2)	[1]	(1)	(14)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Before Tax Amount [Abstract]
Other comprehensive loss before reclassifications, before tax	10,643		(43,810)		22,705	(52,381)
Tax Effect [Abstract]
Unrealized losses arising during holding period, tax effect	(4,076)		16,773		(8,697)	20,056
Net of Tax Amount [Abstract]
Other Comprehensive Loss Before Reclassification Adjustments, Net Of Tax	6,567		(27,037)		14,008	(32,325)
Accumulated Defined Benefit Plans Adjustment [Member]
Before Tax Amount [Abstract]
Other comprehensive loss before reclassifications, before tax	738	[2]	1,337	[2]	1,476	2,674
Tax Effect [Abstract]
Recognized employee benefit plan net periodic benefit cost, tax effect	(282)	[2]	(511)	[2]	(564)	(1,022)
Net of Tax Amount [Abstract]
Other Comprehensive Loss Before Reclassification Adjustments, Net Of Tax	$ 456	[2]	$ 826	[2]	$ 912	$ 1,652

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