EMPLOYEE SAVINGS AND STOCK OWNERSHIP PLAN (Details) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Employee savings and stock ownership plan      
ESOP related expenses $ 1,881,000 $ 1,891,000 $ 2,599,000
ESOP | Full-time employees employed at date of IPO
     
Employee savings and stock ownership plan      
Eligibility age required to receive retirement benefits 21 years    
ESOP | Other salaried employees
     
Employee savings and stock ownership plan      
Eligibility age required to receive retirement benefits 21 years    
Eligibility service period required to receive retirement benefits 1 year    
KSOP
     
Employee savings and stock ownership plan      
Loan receivable from ESOP 20,200,000 21,700,000  
Allocated shares 1,614,572 1,434,964  
Number of suspense shares 1,610,200 1,789,808  
Market value of the unearned shares 17,600,000 17,000,000  
ESOP related expenses $ 2,400,000 $ 2,200,000 $ 2,500,000