Annual report pursuant to Section 13 and 15(d)

Retirement Plans and Related Post Retirement Benefits - Reconciliation of Beginning and Ending Balances of Projected Benefit Obligation (Details)

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Retirement Plans and Related Post Retirement Benefits - Reconciliation of Beginning and Ending Balances of Projected Benefit Obligation (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
SERP      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Balance at beginning of the year $ 25,141 $ 21,533  
Service Cost 200 186 $ 173
Interest Cost 899 897 901
Actuarial (Gain) Loss (3,922) 2,873  
Benefits Paid (348) (348)  
Balance at end of the year 21,970 25,141 21,533
SERP Medical      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Balance at beginning of the year 1,307 1,021  
Service Cost 16 7 5
Interest Cost 46 41 40
Actuarial (Gain) Loss (162) 307  
Benefits Paid (71) (69)  
Balance at end of the year $ 1,136 $ 1,307 $ 1,021