COMMON STOCK (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
COMMON STOCK.
Compensation Expense	$ 1,863,000	$ 1,765,000	$ 3,193,000
Tax Benefit Recognized	649,000	614,000	1,160,000
Employee Stock Purchase Plan
Assumptions used in the model for each grant year
Weighted average fair value of grants	$ 3.19	$ 3.17	$ 2.28
Risk-free interest rate (as a percent)	0.17%	0.18%	0.35%
Expected volatility (as a percent)	24.00%	22.00%	17.00%
Dividend yield (as a percent)	5.00%	2.60%	7.20%
Expected life	12 months	12 months	12 months
The number of historical years over which expected volatility is based	1 year
Changes in restricted stock awards
Nonvested, balance at the beginning of the period (in shares)	70,756	71,326
Nonvested, balance at the end of the period (in shares)	70,850	70,756	71,326
2006 Stock Incentive Plan
Assumptions used for estimating fair value of grants outstanding
Number of shares of common stock provided for grant	650,000
Performance-Based Restricted Stock Awards
Assumptions used for estimating fair value of grants outstanding
Threshold performance level set at percentile level of peer group (as a percent)	20.00%	20.00%	20.00%
Target performance level set at percentile level of peer group (as a percent)	50.00%	50.00%	50.00%
Maximum performance level set at percentile level of peer group (as a percent)	80.00%	80.00%	80.00%
Percentage of shares granted on reaching target performance level	100.00%
Percentage of shares granted on reaching threshold performance level	50.00%
Percentage of shares granted on reaching maximum performance level	200.00%
Unrecognized compensation cost related to estimated outstanding awards	$ 100,000	$ 100,000
Vesting period	3 years
Assumptions used in the model for each grant year
Risk-free interest rate, low end of range (as a percent)	0.16%	0.12%	0.30%
Risk-free interest rate, high end of range (as a percent)	0.25%	0.23%	0.62%
Expected volatility (as a percent)	20.60%	23.80%	26.90%
Dividend yield (as a percent)	4.90%	4.70%	6.50%
Expected forfeiture rates (as a percent)	3.00%	3.00%	3.00%
Plan cycle	3 years	3 years	3 years
Weighted average fair value per share (in dollars per share)	$ 10.94	$ 13.67	$ 37.17
Changes in restricted stock awards
Nonvested, balance at the beginning of the period (in shares)	37,400	47,500	52,200
Granted (in shares)	10,000	10,900	13,000
Vested (in shares)	(7,823)	(39,621)	(15,104)
Awarded in excess of target (in shares)		18,621
Not Awarded (in shares)	(5,677)		(2,596)
Nonvested, balance at the end of the period (in shares)	33,900	37,400	47,500
Weighted Average Grant Date Price
Nonvested, balance at the beginning of the period (in dollars per share)	$ 19.28	$ 19.86	$ 21.57
Granted (in dollars per share)	$ 20.97	$ 21.84	$ 18.36
Awarded/ Vested (in dollars per share)	$ 18.12	$ 21.92	$ 23.81
Awarded in Excess of target (in dollars per share)		$ 21.92
Not Awarded (in dollars per share)	$ 18.12
Nonvested, balance at the end of the period (in dollars per share)	$ 20.25	$ 19.28	$ 19.86
Performance-Based Restricted Stock Awards | Minimum
Assumptions used in the model for each grant year
Expected volatility of peer group stock (as a percent)	12.40%	15.70%	21.70%
Fair value percentage	18.00%	51.00%	138.00%
Performance-Based Restricted Stock Awards | Maximum
Assumptions used in the model for each grant year
Expected volatility of peer group stock (as a percent)	29.20%	57.40%	82.70%
Fair value percentage	96.00%	75.00%	193.70%
Stock Options
Assumptions used for estimating fair value of grants outstanding
Vesting period	3 years
Stock options, expiration term	10 years
Assumptions used in the model for each grant year
Risk-free interest rate, low end of range (as a percent)	0.11%	0.12%	0.45%
Risk-free interest rate, high end of range (as a percent)	0.44%	0.72%	2.34%
Expected volatility (as a percent)	24.00%	25.00%	23.00%
Dividend yield (as a percent)	4.90%	4.70%	6.50%
Expected life	78 months	78 months	78 months
Market value (in dollars per share)	$ 20.38	$ 21.09	$ 22.20
Weighted average fair value per option (in dollars per share)	$ 1.34	$ 2.08	$ 2.02
Time-Vested Restricted Stock Awards
Assumptions used for estimating fair value of grants outstanding
Period from date of termination of employment due to death, retirement or disability during which the pro-rata portion of the awards are distributed	6 months
Vesting period	3 years
Changes in restricted stock awards
Nonvested, balance at the beginning of the period (in shares)	3,433
Granted (in shares)		10,200
Vested (in shares)		794
Distributed (in shares)	(133)	(661)
Forfeited (in shares)		(6,106)
Vested but not distributed (in shares)		133
Nonvested, balance at the end of the period (in shares)	3,300	3,433
Weighted Average Grant Date Price
Nonvested, balance at the beginning of the period (in dollars per share)	$ 21.84
Granted (in dollars per share)		$ 21.84
Awarded/ Vested (in dollars per share)		$ 19.32
Distributed (in dollars per share)	$ 20.13	$ 21.02
Vested but not distributed (in dollars per share)		$ 20.13
Nonvested, balance at the end of the period (in dollars per share)	$ 20.358	$ 21.84