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Summary Of Significant Accounting Policies (Other Income - Net) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Accounting Policies [Abstract] |  |  |
Interest income | $ (2,587) | $ (2,710) | $ (2,162)
Interest on regulatory deferrals | (1,460) | (990) | (1,288)
Equity-related AFUDC | (6,585) | (6,554) | (6,669)
Non-service portion of pension and other postretirement benefit expenses | 8,899 | 5,156 | 7,670
Net (income) loss on investments | (14,299) | 5,369 | 4,160
Other expense (income) | 1,104 | 1,187 | (1,104)
Other income-net | $ (14,928) | $ 1,458 | $ 607

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