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LONG TERM DEBT - Additional Information (Detail)
 12 Months Ended
Apr. 06, 2015
USD ($)
May. 21, 2014
USD ($)
$ / shares
shares
Dec. 07, 2012
USD ($)
Apr. 23, 2012
USD ($)
$ / note
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Dec. 06, 2012
USD ($)
$ / note
Debt Instrument [Line Items]                
Net proceeds from issuance of long term debt         $ 172,304,000 $ 0 $ 0  
Proceeds from issuance of tangible equity units, net of issuance costs         $ 0 $ 64,959,000 $ 0  
Senior Notes                
Debt Instrument [Line Items]                
Minimum redemption period notice required         30 days      
Maximum redemption period notice required         60 days      
Redemption price, percentage         100.00%      
Senior Notes | 7.50% Senior Notes Due April 15, 2020                
Debt Instrument [Line Items]                
Aggregate principal amount issued       $ 33,000,000.0       $ 45,000,000.0
Stated interest rate       7.50% 7.50%      
Sale price of notes to public | $ / note       25.00       25.00
Net proceeds from issuance of long term debt     $ 50,100,000 $ 31,700,000        
Exercise of underwriters' overallotment option     $ 6,800,000          
Senior Notes | 5.25% Senior Notes Due April 15, 2025                
Debt Instrument [Line Items]                
Aggregate principal amount issued $ 175,000,000              
Stated interest rate 5.25%       5.25%      
Net proceeds from issuance of long term debt $ 172,800,000              
Junior Subordinated Debt | 7.50% Amortizing Note Due May 15, 2017                
Debt Instrument [Line Items]                
Stated interest rate   7.50%            
Gross proceeds from issuance of tangible equity units   $ 69,000,000            
Tangible equity units dividend rate   8.00%            
Tangible equity units issued during period, shares | shares   1,380,000            
Tangible equity units issued to underwriter during period, shares | shares   180,000            
Tangible equity units, price per share | $ / shares   $ 50.00            
Tangible equity units, convertible, conversion ratio   10.604556            
Fair value of debt instrument   $ 14,600,000            
Adjustments to additional paid in capital, issuance of tangible equity units   54,400,000            
Tangible equity units issued, issuance costs   4,000,000            
Tangible equity units issued, issuance costs, underwriter discount   3,300,000            
Debt instrument, deferred finance cost   857,000            
Adjustments to additional paid in capital, tangible equity units issued, issuance costs   3,200,000            
Proceeds from issuance of tangible equity units, net of issuance costs   $ 65,000,000