Annual report pursuant to Section 13 and 15(d)

Retirement and Long-Term Incentive Plans - Additional Information (Details)

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Retirement and Long-Term Incentive Plans - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Employer discretionary contribution $ 800,000    
Available shares for future issuance (in shares) 611,887    
Share-based compensation cost charged against income $ 1,774,000 $ 2,795,000 $ 2,741,000
Total unrecognized compensation costs 1,600,000    
Total income tax (expense) benefit under share-based compensation $ 13,000 $ (19,000) $ (300,000)
Recognition of compensation cost, weighted average period 2 years    
Value of awards granted $ 1,000,000    
Total fair value of shares vested $ 2,900,000    
Outstanding stock option awards 0    
Stock option awards granted 0 0 0
Non-employee directors      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock vesting period 6 months    
Employee Stock Option | Long Term Incentive Plan 1997      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares authorized (in shares) 1,000,000    
Employee Stock Option | Long Term Incentive Plan 2002      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares authorized (in shares) 500,000    
Employee Stock Option | Long Term Incentive Plan 2011      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares authorized (in shares) 500,000    
Employee Stock Option | Long Term Incentive Plan 2015      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Shares authorized (in shares) 1,000,000    
Restricted Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock vesting period 3 years    
Performance Shares      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance period awards are earned 3 years    
Performance based share compensation benefit due to reversal of previously recognized expense $ 1,700,000    
Performance based share compensation expense   $ 1,100,000 $ 1,500,000
Amount accrued for stock-based performance award granted 0    
Payout earned for performance based shares granted 0    
Fair value of performance based shares granted   $ 3,800,000 $ 4,700,000
Cash-Based Performance Awards      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Performance based share compensation expense $ 0    
Performance period awards are earned 3 years    
Target amounts payable associated with performance period $ 500,000