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Summary of Significant Accounting Policies (Advances for Construction and Contributions in Aid of Construction) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
Accounting Policies [Abstract] |  |
Refund period for advances for construction received after 1981 | 40 years |
Estimated Refunds of Advances for Construction [Abstract] |  |
2020 | $ 2,890 |
2021 | 2,890 |
2022 | 2,890 |
2023 | 2,878 |
2024 | 2,799 |
Thereafter | 49,631 |
Customer Advances for Construction | 112,339 | $ 80,610
Customer Advances for Construction, Non-Refundable | 21,463 |
Customer Advances for Construction, Refunded on Service Connections | $ 26,898 |
Amortization period for taxes paid relating to advances and contributions | 40 years |

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- Definition For utilities only, represents the carrying amount of the liability as of the balance sheet date for payments received by a utility from its customers in advance of performing its obligations under terms of its construction agreements. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.24) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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