COMPREHENSIVE INCOME (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Before Tax Amount [Abstract]
Other comprehensive (loss) income, before tax	$ (764)		$ (97)		$ 23,416		$ (49,826)
Tax Effect [Abstract]
Other comprehensive (loss) income, tax effect	291		41		(8,970)		19,083
Net of Tax Amount [Abstract]
Other comprehensive (loss) income, net of tax	(473)		(56)		14,446		(30,743)
Net income (loss)	28,778		24,857		88,090		66,417
Comprehensive income	28,305		24,801		102,536		35,674
Reclassification Adjustment For Net Losses (Gains) Realized In Net Income [Member]
Before Tax Amount [Abstract]
Amounts reclassified from accumulated OCI, before tax	(18)	[1]	5	[1]	(19)	[1]	(17)	[1]
Tax Effect [Abstract]
Reclassification adjustment for net gains realized in net income, tax effect	7	[1]	(1)	[1]	7	[1]	7	[1]
Net of Tax Amount [Abstract]
Amounts reclassified from accumulated OCI, net of tax	(11)	[1]	4	[1]	(12)	[1]	(10)	[1]
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Before Tax Amount [Abstract]
Other comprehensive loss before reclassifications, before tax	(1,484)		(1,439)		21,221		(53,820)
Tax Effect [Abstract]
Unrealized losses arising during holding period, tax effect	567		554		(8,130)		20,610
Net of Tax Amount [Abstract]
Other Comprehensive Loss Before Reclassification Adjustments, Net Of Tax	(917)		(885)		13,091		(33,210)
Accumulated Defined Benefit Plans Adjustment [Member]
Before Tax Amount [Abstract]
Other comprehensive loss before reclassifications, before tax	738	[2]	1,337	[2]	2,214	[2]	4,011	[2]
Tax Effect [Abstract]
Recognized employee benefit plan net periodic benefit cost, tax effect	(283)	[2]	(512)	[2]	(847)	[2]	(1,534)	[2]
Net of Tax Amount [Abstract]
Other Comprehensive Loss Before Reclassification Adjustments, Net Of Tax	$ 455	[2]	$ 825	[2]	$ 1,367	[2]	$ 2,477	[2]

[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.