OTHER COMPREHENSIVE INCOME (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net unrealized gains on available-for- sale securities, before tax amount [Abstract]
Unrealized gains (losses) arising during holding period, before tax amount	$ 55,882	$ (8,854)	$ 11,391
Reclassification adjustment for net (gains) realized in net income, before tax amount	(12,127)	470	55
Change in pension funding status before tax amount	(23,963)	(1,423)	18,510
Other comprehensive income (loss), before tax amount	19,792	(9,807)	29,956
Net unrealized gains on available-for- sale securities, tax (expense) benefit [Abstract]
Unrealized gains (losses) arising during holding period, tax (expense) benefit	(21,405)	3,399	(4,368)
Reclassification adjustment for net (gains) losses realized in net income, tax (expense) benefit	4,639	(180)	(21)
Change in pension funding status cost, tax (expense) benefit	9,166	544	(7,080)
Other comprehensive (loss) income, tax (expense) benefit	(7,600)	3,763	(11,469)
Net unrealized gains on available-for- sale securities, net of tax amount [Abstract]
Unrealized gains (losses) arising during holding period, net of tax amount	34,477	(5,455)	7,023
Reclassification adjustment for net (gains) losses realized in net income, net of tax amount	(7,488)	290	34
Change in pension funding status cost, net of tax amount	(14,797)	(879)	11,430
Other comprehensive income (loss), net of tax amount	12,192	(6,044)	18,487
Net income	37,569	22,942	82,729
Comprehensive income	$ 49,761	$ 16,898	$ 101,216