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Investments (Unconsolidated Subsidiaries) (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
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Unconsolidated Subsidiaries |  |
Investment in unconsolidated subsidiaries | $ 390,214 | $ 330,591
Qualified affordable housing project tax credit partnerships |  |
Unconsolidated Subsidiaries |  |
Investment in unconsolidated subsidiaries | 74,895 | 84,607
Other tax credit partnerships |  |
Unconsolidated Subsidiaries |  |
Investment in unconsolidated subsidiaries | 4,980 | 6,118
All other investments, primarily investment fund LPs/LLCs |  |
Unconsolidated Subsidiaries |  |
Investment in unconsolidated subsidiaries | $ 310,339 | $ 239,866

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