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Basis of Presentation (Other Liabilities) (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017 | Jun. 30, 2017
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Organization, Consolidation and Presentation of Financial Statements [Abstract] |  |  |
SPC dividends payable | $ 48,439 | $ 46,925 |
Unpaid dividends | 17,630 | 267,292 | $ 16,524
All other | 103,057 | 123,383 |
Total other liabilities | $ 169,126 | $ 437,600 |

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