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Schedule I - Summay of Investments - Other Than Investments in Related Parties (Details) $ in Thousands | Dec. 31, 2017 USD ($)
--- | ---
Amortized Cost or Cost | $ 5,560,500
Carrying Amount | 5,685,179
Short-term Investments [Member] |
Amortized Cost or Cost | 165,555
Fair Value | 165,555
Carrying Amount | 165,555
Other Investments [Member] |
Amortized Cost or Cost | 132,268
Carrying Amount | 132,268
Preferred Stock [Member] | Banks, trusts, and insurance companies |
Amortized Cost or Cost | 14,115
Fair Value | 14,948
Carrying Amount | 14,948
Held-to-maturity Securities [Member] | Obligations of States and Political Subdivisions [Member] |
Amortized Cost or Cost | 25,154
Fair Value | 26,261
Carrying Amount | 25,238
Held-to-maturity Securities [Member] | Public Utilities |
Amortized Cost or Cost | 7,466
Fair Value | 7,956
Carrying Amount | 7,443
Held-to-maturity Securities [Member] | All other corporate securities |
Amortized Cost or Cost | 9,530
Fair Value | 9,883
Carrying Amount | 9,448
Held-to-maturity Securities [Member] | Fixed Income Securities [Member] |
Amortized Cost or Cost | 42,150
Fair Value | 44,100
Carrying Amount | 42,129
AFS Fixed Income Securities [Member] | US Government Agencies Debt Securities [Member] |
Amortized Cost or Cost | 49,326
Fair Value | 49,740
Carrying Amount | 49,740
AFS Fixed Income Securities [Member] | Foreign Government |
Amortized Cost or Cost | 18,040
Fair Value | 18,555
Carrying Amount | 18,555
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member] |
Amortized Cost or Cost | 1,539,307
Fair Value | 1,582,970
Carrying Amount | 1,582,970
AFS Fixed Income Securities [Member] | Public Utilities |
Amortized Cost or Cost | 50,071
Fair Value | 51,035
Carrying Amount | 51,035
AFS Fixed Income Securities [Member] | All other corporate securities |
Amortized Cost or Cost | 1,538,268
Fair Value | 1,566,433
Carrying Amount | 1,566,433
AFS Fixed Income Securities [Member] | CLO and Other ABS |
Amortized Cost or Cost | 789,152
Fair Value | 795,458
Carrying Amount | 795,458
AFS Fixed Income Securities [Member] | Commercial Mortgage-backed Securities (CMBS) [Member] |
Amortized Cost or Cost | 382,727
Fair Value | 383,449
Carrying Amount | 383,449
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member] |
Amortized Cost or Cost | 709,825
Fair Value | 714,882
Carrying Amount | 714,882
AFS Fixed Income Securities [Member] | Fixed Income Securities [Member] |
Amortized Cost or Cost | 5,076,716
Fair Value | 5,162,522
Carrying Amount | 5,162,522
Equity Securities [Member] | Public Utilities |
Amortized Cost or Cost | 5,957
Fair Value | 6,156
Carrying Amount | 6,156
Equity Securities [Member] | Banks, trusts, and insurance companies |
Amortized Cost or Cost | 34,301
Fair Value | 40,510
Carrying Amount | 40,510
Equity Securities [Member] | Industrial, miscellaneous and all other |
Amortized Cost or Cost | 89,438
Fair Value | 121,091
Carrying Amount | 121,091
Equity Securities [Member] | Common Stock [Member] |
Amortized Cost or Cost | 129,696
Fair Value | 167,757
Carrying Amount | 167,757
Equity Securities [Member] | Preferred Stock [Member] |
Amortized Cost or Cost | 14,115
Fair Value | 14,948
Carrying Amount | 14,948
Equity Securities [Member] | Equity Securities [Member] |
Amortized Cost or Cost | 143,811
Fair Value | 182,705
Carrying Amount | $ 182,705

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- Definition This element represents the carrying (reported) amount of the entity's investments as of the balance sheet date. This amount may represent the individual investment's or group of similar investments' original cost, fair value, or such other amount at which the investment is shown in the entity's balance sheet. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 7 -Subparagraph (SX 210.12-15) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611379-123010 + Details
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