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Fair Value Measurement (Assets and Liabilities Measured at Fair Value) (Details) - USD ($) $ in Thousands | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Assets: |  |
Fixed maturities, available for sale | $ 2,125,921 | $ 2,280,242
Equity investments | 496,026 | 470,609
Fair Value | 297,762 | 230,889
Investment in unconsolidated subsidiaries |  |
Assets: |  |
Fair Value | 277,505 | 210,759
Level 3 | Corporate debt, limited observable inputs |  |
Assets: |  |
Total assets categorized within the fair value hierarchy | 8,380 | 13,703
Level 3 | Other investments |  |
Assets: |  |
Total assets categorized within the fair value hierarchy | 5 | 409
Recurring |  |
Assets: |  |
Other assets | 2,588 | 1,731
Total assets categorized within the fair value hierarchy | 2,880,015 | 3,216,879
Total assets at fair value | 3,177,777 | 3,447,768
Recurring | U.S. Treasury obligations |  |
Assets: |  |
Fixed maturities, available for sale | 146,457 | 133,627
Recurring | U.S. Government-sponsored enterprise obligations |  |
Assets: |  |
Fixed maturities, available for sale | 31,702 | 20,956
Recurring | State and municipal bonds |  |
Assets: |  |
Fixed maturities, available for sale | 331,100 | 632,243
Recurring | Corporate debt, multiple observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 1,187,247 | 1,153,455
Recurring | Corporate debt, limited observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 8,380 | 13,703
Recurring | Residential mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 204,236 | 197,844
Recurring | Agency commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 13,812 | 10,742
Recurring | Other commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 32,715 | 15,961
Recurring | Other asset-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 170,272 | 101,711
Recurring | Corporate Debt |  |
Assets: |  |
Trading Securities | 29,772 |
Recurring | Financial |  |
Assets: |  |
Equity investments | 74,656 | 76,051
Recurring | Utilities/Energy |  |
Assets: |  |
Equity investments | 57,936 | 54,388
Recurring | Consumer oriented |  |
Assets: |  |
Equity investments | 55,459 | 54,529
Recurring | Industrial |  |
Assets: |  |
Equity investments | 46,285 | 53,936
Recurring | Bond funds |  |
Assets: |  |
Equity investments | 146,795 | 156,563
Recurring | All other |  |
Assets: |  |
Equity investments | 94,638 | 75,142
Recurring | Short-term investments |  |
Assets: |  |
Short-term and other investments | 212,945 | 432,126
Recurring | Other investments |  |
Assets: |  |
Short-term and other investments | 33,020 | 32,171
Fair Value |  | 20,130
Recurring | Investment in unconsolidated subsidiaries |  |
Assets: |  |
Fair Value |  | 210,759
Recurring | Level 1 |  |
Assets: |  |
Other assets | 0 | 0
Total assets categorized within the fair value hierarchy | 678,397 | 877,791
Recurring | Level 1 | U.S. Treasury obligations |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | U.S. Government-sponsored enterprise obligations |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | State and municipal bonds |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | Corporate debt, multiple observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 2,262 | 2,371
Recurring | Level 1 | Corporate debt, limited observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | Residential mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | Agency commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | Other commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | Other asset-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 1 | Corporate Debt |  |
Assets: |  |
Trading Securities | 0 |
Recurring | Level 1 | Financial |  |
Assets: |  |
Equity investments | 74,656 | 76,051
Recurring | Level 1 | Utilities/Energy |  |
Assets: |  |
Equity investments | 57,936 | 54,388
Recurring | Level 1 | Consumer oriented |  |
Assets: |  |
Equity investments | 55,459 | 54,529
Recurring | Level 1 | Industrial |  |
Assets: |  |
Equity investments | 46,285 | 53,936
Recurring | Level 1 | Bond funds |  |
Assets: |  |
Equity investments | 146,795 | 156,563
Recurring | Level 1 | All other |  |
Assets: |  |
Equity investments | 94,638 | 75,142
Recurring | Level 1 | Short-term investments |  |
Assets: |  |
Short-term and other investments | 200,366 | 404,204
Recurring | Level 1 | Other investments |  |
Assets: |  |
Short-term and other investments | 0 | 607
Recurring | Level 2 |  |
Assets: |  |
Other assets | 2,588 | 1,731
Total assets categorized within the fair value hierarchy | 2,183,813 | 2,319,990
Recurring | Level 2 | U.S. Treasury obligations |  |
Assets: |  |
Fixed maturities, available for sale | 146,457 | 133,627
Recurring | Level 2 | U.S. Government-sponsored enterprise obligations |  |
Assets: |  |
Fixed maturities, available for sale | 31,702 | 20,956
Recurring | Level 2 | State and municipal bonds |  |
Assets: |  |
Fixed maturities, available for sale | 331,100 | 632,243
Recurring | Level 2 | Corporate debt, multiple observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 1,184,985 | 1,151,084
Recurring | Level 2 | Corporate debt, limited observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 2 | Residential mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 204,236 | 196,789
Recurring | Level 2 | Agency commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 13,812 | 10,742
Recurring | Level 2 | Other commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 32,715 | 15,961
Recurring | Level 2 | Other asset-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 160,852 | 97,780
Recurring | Level 2 | Corporate Debt |  |
Assets: |  |
Trading Securities | 29,772 |
Recurring | Level 2 | Financial |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 2 | Utilities/Energy |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 2 | Consumer oriented |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 2 | Industrial |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 2 | Bond funds |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 2 | All other |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 2 | Short-term investments |  |
Assets: |  |
Short-term and other investments | 12,579 | 27,922
Recurring | Level 2 | Other investments |  |
Assets: |  |
Short-term and other investments | 33,015 | 31,155
Recurring | Level 3 |  |
Assets: |  |
Other assets | 0 | 0
Total assets categorized within the fair value hierarchy | 17,805 | 19,098
Recurring | Level 3 | U.S. Treasury obligations |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 3 | U.S. Government-sponsored enterprise obligations |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 3 | State and municipal bonds |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 3 | Corporate debt, multiple observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 3 | Corporate debt, limited observable inputs |  |
Assets: |  |
Fixed maturities, available for sale | 8,380 | 13,703
Recurring | Level 3 | Residential mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 1,055
Recurring | Level 3 | Agency commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 3 | Other commercial mortgage-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 0 | 0
Recurring | Level 3 | Other asset-backed securities |  |
Assets: |  |
Fixed maturities, available for sale | 9,420 | 3,931
Recurring | Level 3 | Corporate Debt |  |
Assets: |  |
Trading Securities | 0 |
Recurring | Level 3 | Financial |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 3 | Utilities/Energy |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 3 | Consumer oriented |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 3 | Industrial |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 3 | Bond funds |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 3 | All other |  |
Assets: |  |
Equity investments | 0 | 0
Recurring | Level 3 | Short-term investments |  |
Assets: |  |
Short-term and other investments | 0 | 0
Recurring | Level 3 | Other investments |  |
Assets: |  |
Short-term and other investments | 5 | 409
Mortgage fund | Other investments |  |
Assets: |  |
Fair Value | 0 | 20,130
Mortgage fund | Equities |  |
Assets: |  |
Fair Value | $ 20,257 | $ 0

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