STOCK-BASED COMPENSATION PLAN (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of shares in the aggregate that may be issued under the 1997 Stock-Based Compensation Plan (no more than)	2,000,000
Number of options granted	0		0	0
Actual amount of shares that ultimately vest of the original share units granted, minimum	0.00%
Actual amount of shares that ultimately vest of the original share units granted, maximum	150.00%
Fair value per share (in dollars per share)	$ 48.79		$ 50.73
Expected volatility, measurement period	3 years
Net Expense	$ 1,746,000		$ 2,764,000	$ 2,761,000
Capitalized	(147,000)		(237,000)	(231,000)
Unrecognized compensation cost of awards granted under the plan	2,800,000
Weighted average period over which unrecognized compensation cost is to be recognized (in years)	1 year 8 months 12 days
Weighted Average Fair Value
Nonvested Shares Outstanding, beginning balance (in dollars per share)	$ 50.73
Granted (in dollars per share)	$ 49.40
Vested (in dollars per share)	$ 53.42	[1]
Cancelled/Forfeited (in dollars per share)	$ 49.49
Nonvested Shares Outstanding, ending balance (in dollars per share)	$ 48.79		$ 50.73
Cost [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	1,893,000		3,001,000	2,992,000
Jan. 2012 - TSR [Member] | Cost [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	1,100,000
Officers and Key Employees [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted	68,263		56,464	40,955
Vesting period of shares	3 years		3 years	3 years
The range of the actual amount of shares that ultimately vest of the original share units granted (in hundredths)	0% to 150%
Shares outstanding (in shares)	111,938		94,192
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, beginning balance (in shares)	94,192
Granted (in shares)	68,263		56,464	40,955
Vested (in shares)	(36,536)	[1]
Cancelled/Forfeited (in shares)	(13,981)
Nonvested shares outstanding, ending balance (in shares)	111,938		94,192
Weighted Average Fair Value
Number of shares awarded during the period	0		66,077	33,322
Market value of shares awarded			3,300,000	1,900,000
Officers and Key Employees [Member] | Cost [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	1,260,000		2,236,000	2,096,000
Officers and Key Employees [Member] | Jan. 2013 - TSR [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares outstanding (in shares)	24,797
Fair value per share (in dollars per share)	$ 44.38
Expected Volatility	21.10%
Risk-Free Interest Rate	0.40%
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, ending balance (in shares)	24,797
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in dollars per share)	$ 44.38
Officers and Key Employees [Member] | Jan. 2013 - EPS [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares outstanding (in shares)	24,797
Fair value per share (in dollars per share)	$ 51.18
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, ending balance (in shares)	24,797
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in dollars per share)	$ 51.18
Officers and Key Employees [Member] | Jan. 2014 - TSR [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares outstanding (in shares)	31,172
Fair value per share (in dollars per share)	$ 42.62
Expected Volatility	20.00%
Risk-Free Interest Rate	0.80%
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, ending balance (in shares)	31,172
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in dollars per share)	$ 42.62
Officers and Key Employees [Member] | Jan. 2014 - EPS [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares outstanding (in shares)	31,172
Fair value per share (in dollars per share)	$ 54.44
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, ending balance (in shares)	31,172
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in dollars per share)	$ 54.44
Officers and Key Employees [Member] | Jan. 2012 [Member]
Weighted Average Fair Value
Shares expected to be awarded to officers and key employees	0
Directors [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted	11,610		12,285	9,904
Vesting period of shares	12 months		12 months	3 years
Percent of shares vested, Directors	100.00%
Shares outstanding (in shares)	11,610		19,617
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, beginning balance (in shares)	19,617
Granted (in shares)	11,610		12,285	9,904
Vested (in shares)	(19,617)	[1]
Cancelled/Forfeited (in shares)	0
Nonvested shares outstanding, ending balance (in shares)	11,610		19,617
Weighted Average Fair Value
Market value of shares awarded	600,000		600,000	600,000
Directors [Member] | Cost [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Net Expense	$ 633,000		$ 765,000	$ 896,000
Directors [Member] | Jan. 2014 [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares outstanding (in shares)	11,610
Fair value per share (in dollars per share)	$ 54.51
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Nonvested shares outstanding, ending balance (in shares)	11,610
Weighted Average Fair Value
Nonvested Shares Outstanding, ending balance (in dollars per share)	$ 54.51
Stock Appreciation Rights (SARs) [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Number of awards granted	0		0	0
Restricted stock award activity, excluding accrued dividend equivalents [Roll Forward}
Granted (in shares)	0		0	0

[1] Performance targets during the three-year vesting period were not attained for the January 2012 grant. As a result, no shares will be awarded in 2015.