Annual report pursuant to Section 13 and 15(d)

Benefit Plans - 1% Change in Accumulated Postretirement Benefit Obligation (Details)

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Benefit Plans - 1% Change in Accumulated Postretirement Benefit Obligation (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2018
USD ($)
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate  
Accumulated postretirement benefit obligation (1 percent increase) $ 157
Accumulated postretirement benefit obligation (1 percent decrease) (138)
Periodic postretirement benefit cost (1 percent increase) 6
Periodic postretirement benefit cost (1 percent decrease) $ (5)