STOCK-BASED COMPENSATION PLANS (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock-based compensation plans
Number of shares counted against the share limit for each restricted stock granted	3
Unvested Stock Award shares
Non-vested Stock Awards Outstanding, Number of Shares
Balance at the beginning of the period (in shares)	334,000
Granted (in shares)	187,000
Stock awards vested (in shares)	(88,000)
Forfeited (in shares)	(9,000)
Balance at the end of the period (in shares)	424,000	334,000
Non-vested Stock Awards Outstanding, Weighted-Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share)	$ 23.26
Granted (in dollars per share)	$ 24.60	$ 24.49	$ 23.76
Stock awards vested (in dollars per share)	$ 22.86
Forfeited (in dollars per share)	$ 23.46
Balance at the end of the period (in dollars per share)	$ 24.33	$ 23.26
Stock-based compensation plans
Total compensation cost	$ 3,800,000	$ 2,100,000	$ 2,000,000
Total recognized tax benefit	1,500,000	900,000	800,000
Weighted average fair value of stock awards granted (in dollars per share)	$ 24.60	$ 24.49	$ 23.76
Total fair value of awards vested	2,000,000	1,900,000	1,400,000
Unrecognized stock-based compensation expense	6,100,000
Unvested Stock Award shares | Maximum
Stock-based compensation plans
Vesting period	5 years
Expected weighted-average period for recognition of unrecognized compensation	2 years
Options
Stock Options Outstanding, Number of Shares
Balance at the beginning of the period (in shares)	442,000
Stock options exercised (in shares)	(90,000)
Expired (in shares)	(70,000)
Balance at the end of the period (in shares)	282,000	442,000
Exercisable options at the end of the period (in shares)	282,000
Stock Options Outstanding, Weighted-Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 20.41
Stock options exercised (in dollars per share)	$ 11.77
Expired (in dollars per share)	$ 37.22
Balance at the end of the period (in dollars per share)	$ 20.42	$ 20.41
Exercisable options at the end of the period (in dollars per share)	$ 20.72
Stock-based compensation plans
Total compensation cost	41,000	860,000	240,000
Total recognized tax benefit	16,000	347,000	97,000
Unrecognized stock-based compensation expense	0	41,000
Contractual life	10 years
Weighted average remaining contractual term for options outstanding	4 years
Total intrinsic value	$ 1,200,000	$ 2,900,000	$ 2,700,000
Options | Maximum
Stock-based compensation plans
Vesting period	5 years
2011 Equity Compensation Plan
Stock-based compensation plans
Number of shares authorized under the plan	1,400,000
Number of shares available for grant under the plan	7,000
2011 Equity Compensation Plan | Options
Stock-based compensation plans
Number of shares counted against the share limit for each restricted stock granted	1
2013 Equity Compensation Plan
Stock-based compensation plans
Number of shares authorized under the plan	1,030,000
Number of shares available for grant under the plan	961,000
2013 Equity Compensation Plan | Unvested Stock Award shares
Stock-based compensation plans
Number of shares counted against the share limit for each restricted stock granted	3
2013 Equity Compensation Plan | Options
Stock-based compensation plans
Number of shares counted against the share limit for each restricted stock granted	1