ACCUMULATED OTHER COMPREHENSIVE INCOME - Components of Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at December 31, 2013	$ 59,010	[1]
Other comprehensive income before reclassifications	10,894	[1]
Amounts reclassified from accumulated other comprehensive income	(1,508)	[1]
Other comprehensive income	9,386	[1]	5,484
Balance at March 31, 2014	68,396	[1]
Unrealized Gains and (Losses) on Available-for-sale securities
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at December 31, 2013	48,376	[1]
Other comprehensive income before reclassifications	10,894	[1]
Amounts reclassified from accumulated other comprehensive income	(1,059)	[1]
Other comprehensive income	9,835	[1]
Balance at March 31, 2014	58,211	[1]
Unrecognized pension and postretirement benefit obligations
Accumulated Other Comprehensive Income Loss [Line Items]
Balance at December 31, 2013	10,634	[1]
Other comprehensive income before reclassifications	0	[1]
Amounts reclassified from accumulated other comprehensive income	(449)	[1]
Other comprehensive income	(449)	[1]
Balance at March 31, 2014	$ 10,185	[1]

[1] All amounts are net of tax. Amounts in parentheses indicate debits.