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Basis of Accounting and Consolidation Basis of Accounting and Consolidation (Stock Issuance) (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 9 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 15, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Dec. 31, 2018 | Aug. 16, 2017
Capital Raise [Abstract] |  |  |  |  |
Common stock, par value (in dollars per share) |  | $ 4 |  | $ 4 |
Proceeds from issuance of common stock |  | $ 470 | $ 36,519 |  |
Capital Raise [Member] |  |  |  |  |
Capital Raise [Abstract] |  |  |  |  |
shares underwriters agreed to purchase |  | 823,799 |  |  |
Shares Issued, Price Per Share | $ 38.00 |  |  |  |
Underwriters Option to Purchase Shares |  | 123,569 |  |  |
Shares, Issued | 947,368 |  |  |  |
Proceeds from issuance of common stock | $ 34,000 |  |  |  |
At The Market Program [Member] |  |  |  |  |
Balance of Common Stock Available Under ATM |  | $ 16,530 |  |  | $ 20,000

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