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Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands | 9 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017 | Dec. 31, 2016
Interest | $ 15,449 | $ 15,356 |  |
Federal income tax | 7,193 | 39,000 |  |
Assets acquired under capital lease arrangements | 4,114 | 278 |  |
Cash | 446 |  | $ 534 |
Restricted cash | 12,386 |  | 44,176 |
Total cash and restricted cash shown in the Statements of Cash Flows | 12,832 | 18,659 | $ 44,710 | $ 37,405
AFS Fixed Income Securities [Member] |  |  |  |
Corporate actions related to securities | 32,757 | 6,192 |  |
Equity Securities [Member] |  |  |  |
Corporate actions related to securities | $ 944 | $ 4,725 |  |

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