| **Capitalization**            | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
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| **Capitalization [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Capitalization                | Note 5 – Capitalization 

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In February 2016, the Company amended its unsecured revolving credit facility to extend the expiration from March 2017 to February 2021, to increase the facility from $200,000 to $250,000, and to add a fourth bank to the lending group.  Funds borrowed under this facility are classified as long-term debt and are used to provide working capital as well as support for letters of credit for insurance policies and other financing arrangements.  Interest under this facility is based at the Company’s option, on the prime rate, an adjusted Euro-Rate, an adjusted federal funds rate or at rates offered by the banks.  A facility fee is charged on the total commitment amount of the agreement.  

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