STOCK OWNERSHIP AND BENEFIT PLANS (Details 3) (USD $) In Thousands, except Share data, unless otherwise specified	76 Months Ended	12 Months Ended
	Dec. 31, 2012 Restricted stock and restricted stock units	Dec. 31, 2012 Restricted stock and restricted stock units Executive officers and employees	Dec. 31, 2012 Restricted stock	Dec. 31, 2011 Restricted stock	Dec. 31, 2010 Restricted stock	Dec. 31, 2008 Restricted stock Supplemental executive retirement plan	Dec. 31, 2012 Restricted stock units	Dec. 31, 2011 Restricted stock units	Dec. 31, 2010 Restricted stock units	Dec. 31, 2012 Incentive stock options	Dec. 31, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 31, 2010 Stock options
Stock ownership and benefit plans
Stock-based compensation expense resulting from accelerated vesting of awards (in dollars)			$ 672
Annual vesting percentage		33.00%				100.00%				25.00%
Number of shares granted	805,850		116,900	116,500	104,000	90,000	50,200	32,500	28,000
Shares
Balance at the beginning of the period (in shares)			261,829	237,489	198,650		53,998	34,583	15,166
Granted (in shares)	805,850		116,900	116,500	104,000	90,000	50,200	32,500	28,000
Vested (in shares)			(136,344)	(90,660)	(65,161)		(20,769)	(13,085)	(8,583)
Forfeited (in shares)				(1,500)
Balance at the end of the period (in shares)			242,385	261,829	237,489		83,429	53,998	34,583
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share)			$ 30.59	$ 32.82	$ 38.39		$ 20.43	$ 19.59	$ 15.96
Granted (in dollars per share)			$ 20.74	$ 20.90	$ 19.95		$ 20.44	$ 20.45	$ 20.44
Vested (in dollars per share)			$ 27.20	$ 24.16	$ 29.26		$ 20.43	$ 18.24	$ 15.97
Forfeited (in dollars per share)				$ 18.79
Balance at the end of the period (in dollars per share)			$ 27.75	$ 30.59	$ 32.82		$ 20.44	$ 20.43	$ 19.59
Unrecognized stock-based compensation
Unrecognized stock-based compensation related to unvested awards			1,802				976
Weighted average period over which the cost is expected to be recognized			1 year 2 months 23 days				1 year 6 months
Expiration period from the date of grant										10 years
Options
Balance at the beginning of the period (in shares)											15,500	19,700	28,000
Exercised (in shares)												(4,200)	(8,300)
Balance at the end of the period (in shares)											15,500	15,500	19,700
Exercisable at the end of the period (in shares)											15,500
Weighted Average Exercise Period
Balance at the beginning of the period (in dollars per share)											$ 14.92	$ 12.74	$ 10.37
Exercised (in dollars per share)												$ 4.71	$ 4.75
Balance at the end of the period (in dollars per share)											$ 14.92	$ 14.92	$ 12.74
Exercisable at the end of the period (in dollars per share)											$ 14.92
Weighted Average Remaining Contractual Term
Outstanding at the end of the period											2 years 3 months 4 days
Exercisable at the end of the period											2 years 3 months 4 days
Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)											51
Exercisable at the end of the period (in dollars)											51
Stock options, additional disclosures
Intrinsic value of options exercised											0	74	98
Unrecognized compensation											$ 0	$ 0	$ 0