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CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Postretirement benefits:      
Net actuarial gain (loss), income taxes $ 749 $ (704) $ 1,544
Prior service credit, income taxes 0 0 (3,194)
Amortization of prior service cost, income taxes $ 162 $ 162 $ 1,010