EMPLOYEE BENEFITS - Equity Incentive Plans (Details)	Jun. 30, 2010 shares	Jun. 21, 2006 shares	Dec. 31, 2017 stock_plan shares	Dec. 31, 2016 shares	Dec. 31, 2015 shares	Jul. 28, 2014 shares
Employee Benefits
Number of stock option plans frozen | stock_plan			2
Employee And Directors Time Based Options
Employee Benefits
Options outstanding (in shares)			882,881	894,015	1,081,901
2014 Plan
Employee Benefits
Number of shares or units authorized for grants (in shares)						1,273,838
2014 Plan | Employee And Directors Time Based Options
Employee Benefits
Options outstanding (in shares)			428,168	389,500
2010 Option Plan | Employee And Directors Stock Options
Employee Benefits
Number of shares or units authorized for grants (in shares)	2,239,906
Vesting period	4 years
2010 Option Plan | Employee And Directors Time Based Options
Employee Benefits
Options outstanding (in shares)			367,213	377,015
2010 Option Plan | Employee And Directors Performance Options
Employee Benefits
Options outstanding (in shares)			992,864	1,020,242
2010 Option Plan | Employee And Directors Super Performance Options
Employee Benefits
Options outstanding (in shares)			308,054	316,550
2006 Option Plan
Employee Benefits
Number of shares or units authorized for grants (in shares)		450,000
Options outstanding (in shares)			87,500	127,500
Vesting period		4 years
Term of awards		10 years