Investments - Schedule of Fixed Maturity and Equity Security Investments Available for Sale with Unrealized Losses (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value $ 145,189 $ 558,852
Less Than 12 Months, Unrealized Losses 2,056 26,242
12 Months or Longer, Fair Value 233,038 76,954
12 Months or Longer, Unrealized Losses 11,357 7,639
Fair Value, Total 378,227 635,806
Unrealized Losses, Total 13,413 33,881
U.S. Treasury securities and obligations of U.S. Government
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 10,549 44,951
Less Than 12 Months, Unrealized Losses 55 1,795
12 Months or Longer, Fair Value 9,762 749
12 Months or Longer, Unrealized Losses 313 36
Fair Value, Total 20,311 45,700
Unrealized Losses, Total 368 1,831
Federal agency issued residential mortgage-backed securities
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 67 [1] 37 [1]
Less Than 12 Months, Unrealized Losses 2 [1] 0 [1]
12 Months or Longer, Fair Value 287 [1] 288 [1]
12 Months or Longer, Unrealized Losses 0 [1] 2 [1]
Fair Value, Total 354 [1] 325 [1]
Unrealized Losses, Total 2 2
US treasury securities, subtotal
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 10,616 44,988
Less Than 12 Months, Unrealized Losses 57 1,795
12 Months or Longer, Fair Value 10,049 1,037
12 Months or Longer, Unrealized Losses 313 38
Fair Value, Total 20,665 46,025
Unrealized Losses, Total 370 1,833
Industrial
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 26,336 146,454
Less Than 12 Months, Unrealized Losses 99 5,718
12 Months or Longer, Fair Value 49,956 22,071
12 Months or Longer, Unrealized Losses 2,275 1,949
Fair Value, Total 76,292 168,525
Unrealized Losses, Total 2,374 7,667
Energy
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 25,432 70,015
Less Than 12 Months, Unrealized Losses 867 3,366
12 Months or Longer, Fair Value 37,074 5,518
12 Months or Longer, Unrealized Losses 1,343 466
Fair Value, Total 62,506 75,533
Unrealized Losses, Total 2,210 3,832
Communications and technology
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 11,985 43,477
Less Than 12 Months, Unrealized Losses 157 1,672
12 Months or Longer, Fair Value 14,643 0
12 Months or Longer, Unrealized Losses 356 0
Fair Value, Total 26,628 43,477
Unrealized Losses, Total 513 1,672
Financial
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 5,000 25,300
Less Than 12 Months, Unrealized Losses 1 866
12 Months or Longer, Fair Value 16,081 4,680
12 Months or Longer, Unrealized Losses 841 1,174
Fair Value, Total 21,081 29,980
Unrealized Losses, Total 842 2,040
Consumer
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 43,604 136,745
Less Than 12 Months, Unrealized Losses 491 5,807
12 Months or Longer, Fair Value 39,686 0
12 Months or Longer, Unrealized Losses 1,602 0
Fair Value, Total 83,290 136,745
Unrealized Losses, Total 2,093 5,807
Public utilities
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 6,473 17,476
Less Than 12 Months, Unrealized Losses 13 575
12 Months or Longer, Fair Value 6,689 3,617
12 Months or Longer, Unrealized Losses 307 379
Fair Value, Total 13,162 21,093
Unrealized Losses, Total 320 954
Corporate obligations, subtotal
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 118,830 439,467
Less Than 12 Months, Unrealized Losses 1,628 18,004
12 Months or Longer, Fair Value 164,129 35,886
12 Months or Longer, Unrealized Losses 6,724 3,968
Fair Value, Total 282,959 475,353
Unrealized Losses, Total 8,352 21,972
Corporate private-labeled residential mortgage-backed securities
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 4,581 33,179
Less Than 12 Months, Unrealized Losses 144 916
12 Months or Longer, Fair Value 0 0
12 Months or Longer, Unrealized Losses 0 0
Fair Value, Total 4,581 33,179
Unrealized Losses, Total 144 916
Municipal securities
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 3,030 2,044
Less Than 12 Months, Unrealized Losses 4 5
12 Months or Longer, Fair Value 0 0
12 Months or Longer, Unrealized Losses 0 0
Fair Value, Total 3,030 2,044
Unrealized Losses, Total 4 5
Other
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 6,662 16,691
Less Than 12 Months, Unrealized Losses 181 726
12 Months or Longer, Fair Value 38,132 39,900
12 Months or Longer, Unrealized Losses 2,637 3,591
Fair Value, Total 44,794 56,591
Unrealized Losses, Total 2,818 4,317
Redeemable preferred stocks
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 1,470 12,752
Less Than 12 Months, Unrealized Losses 42 2,392
12 Months or Longer, Fair Value 9,220 0
12 Months or Longer, Unrealized Losses 906 0
Fair Value, Total 10,690 12,752
Unrealized Losses, Total 948 2,392
Fixed maturity securities
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 145,189 549,121
Less Than 12 Months, Unrealized Losses 2,056 23,838
12 Months or Longer, Fair Value 221,530 76,823
12 Months or Longer, Unrealized Losses 10,580 7,597
Fair Value, Total 366,719 625,944
Unrealized Losses, Total 12,636 31,435
Equity securities
    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 0 9,731
Less Than 12 Months, Unrealized Losses 0 2,404
12 Months or Longer, Fair Value 11,508 131
12 Months or Longer, Unrealized Losses 777 42
Fair Value, Total 11,508 9,862
Unrealized Losses, Total $ 777 $ 2,446
[1] Federal agency securities are not backed by the full faith and credit of the U.S. Government.