Investments (Details) (USD $) | 3 Months Ended | 9 Months Ended | 12 Months Ended |
In Thousands, unless otherwise specified | Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013 | Dec. 31, 2013 |
| Security | Security | Security |
| Agreement | Agreement | |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Cost or amortized cost | $431,167 | ' | $431,167 | ' | ' |
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Applicable federal income taxes | -29,508 | ' | ' | ' | -26,432 |
Net unrealized gains - net of tax | 54,799 | ' | ' | ' | 49,089 |
Available-for-sale securities continuous unrealized loss position [Abstract] | ' | ' | ' | ' | ' |
Number of Securities, total | 519 | ' | 519 | ' | 516 |
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract] | ' | ' | ' | ' | ' |
Fair value, total | 146,326 | ' | 146,326 | ' | 145,056 |
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract] | ' | ' | ' | ' | ' |
Gross unrealized loss, total | ' | ' | -4,692 | ' | -4,584 |
Available-for-sale securities debt maturities fair value [Abstract] | ' | ' | ' | ' | ' |
One year or less, Fair Value | 145,547 | ' | 145,547 | ' | ' |
Excess of one year to five years, Fair Value | 154,266 | ' | 154,266 | ' | ' |
Excess of five years to ten years, Fair Value | 46,520 | ' | 46,520 | ' | ' |
Excess of ten years, Fair Value | 8,987 | ' | 8,987 | ' | ' |
Contractual maturities, Fair Value | 355,320 | ' | 355,320 | ' | ' |
Asset-backed securities, Fair Value | 76,481 | ' | 76,481 | ' | ' |
Total, Fair Value | 431,801 | ' | 431,801 | ' | ' |
Available-for-sale securities debt maturities amortized cost basis [Abstract] | ' | ' | ' | ' | ' |
One year or less, Cost or Amortized Cost Basis | 145,511 | ' | 145,511 | ' | ' |
Excess of one year to five years, Cost or Amortized Cost Basis | 155,127 | ' | 155,127 | ' | ' |
Excess of five years to ten years, Cost or Amortized Cost Basis | 46,078 | ' | 46,078 | ' | ' |
Excess of ten years, Cost or Amortized Cost Basis | 8,340 | ' | 8,340 | ' | ' |
Contractual maturities, Cost or Amortized Cost Basis | 355,056 | ' | 355,056 | ' | ' |
Asset-backed securities, Cost or Amortized Cost Basis | 76,111 | ' | 76,111 | ' | ' |
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract] | ' | ' | ' | ' | ' |
Limited partnerships - net gain (loss) | -1,064 | -211 | 7,204 | 2,227 | ' |
Net realized gains on investments | 658 | 1,430 | 12,817 | 16,496 | ' |
Available for sale securities gain loss activity [Abstract] | ' | ' | ' | ' | ' |
Realized net gains on the disposal of securities | 2,223 | 1,090 | 5,837 | 11,888 | ' |
Mark-to-market adjustment | -118 | 342 | 151 | 747 | ' |
Equity in gains (losses) of limited partnership investments - realized and unrealized | -1,064 | -211 | 7,204 | 2,227 | ' |
Write-downs based upon objective criteria | -441 | -4 | -546 | -78 | ' |
Recovery of prior write-downs upon sale or disposal | 58 | 213 | 171 | 1,712 | ' |
Net realized gains on investments | 658 | 1,430 | 12,817 | 16,496 | ' |
Net unrealized gain (loss) on investments | 334 | ' | 5,841 | ' | ' |
Net unrealized gains in limited partnership | ' | ' | 13,305 | ' | ' |
Undistributed earnings of limited partnership, net of taxes | 28,923 | ' | 28,923 | ' | ' |
Committed funds for bridge loans | 18,750 | ' | 18,750 | ' | ' |
Number of bridge loan agreements | 3 | ' | 3 | ' | ' |
U.S. government obligations [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 123,933 | ' | 123,933 | ' | 113,389 |
Cost or amortized cost | 123,859 | ' | 123,859 | ' | 113,348 |
Gross unrealized gains | 125 | ' | 125 | ' | 81 |
Gross unrealized losses | -51 | ' | -51 | ' | -40 |
Net unrealized gains (losses) | 74 | ' | 74 | ' | 41 |
Residential mortgage-backed securities [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 7,349 | ' | 7,349 | ' | 13,252 |
Cost or amortized cost | 7,084 | ' | 7,084 | ' | 12,058 |
Gross unrealized gains | 322 | ' | 322 | ' | 1,334 |
Gross unrealized losses | -57 | ' | -57 | ' | -140 |
Net unrealized gains (losses) | 265 | ' | 265 | ' | 1,194 |
Commercial mortgage-backed securities [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 35,694 | ' | 35,694 | ' | 28,565 |
Cost or amortized cost | 35,132 | ' | 35,132 | ' | 28,406 |
Gross unrealized gains | 737 | ' | 737 | ' | 308 |
Gross unrealized losses | -175 | ' | -175 | ' | -149 |
Net unrealized gains (losses) | 562 | ' | 562 | ' | 159 |
States and municipal obligations [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 105,382 | ' | 105,382 | ' | 115,250 |
Cost or amortized cost | 104,534 | ' | 104,534 | ' | 115,278 |
Gross unrealized gains | 882 | ' | 882 | ' | 407 |
Gross unrealized losses | -34 | ' | -34 | ' | -435 |
Net unrealized gains (losses) | 848 | ' | 848 | ' | -28 |
Corporate securities [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 129,497 | ' | 129,497 | ' | 137,215 |
Cost or amortized cost | 130,186 | ' | 130,186 | ' | 136,991 |
Gross unrealized gains | 2,185 | ' | 2,185 | ' | 3,207 |
Gross unrealized losses | -2,874 | ' | -2,874 | ' | -2,983 |
Net unrealized gains (losses) | -689 | ' | -689 | ' | 224 |
Foreign government obligations [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 29,946 | ' | 29,946 | ' | 23,879 |
Cost or amortized cost | 30,372 | ' | 30,372 | ' | 23,689 |
Gross unrealized gains | 185 | ' | 185 | ' | 588 |
Gross unrealized losses | -611 | ' | -611 | ' | -398 |
Net unrealized gains (losses) | -426 | ' | -426 | ' | 190 |
Total fixed maturities [Member] | ' | ' | ' | ' | ' |
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 431,801 | ' | 431,801 | ' | 431,550 |
Cost or amortized cost | 431,167 | ' | 431,167 | ' | 429,770 |
Gross unrealized gains | 4,436 | ' | 4,436 | ' | 5,925 |
Gross unrealized losses | -3,802 | ' | -3,802 | ' | -4,145 |
Net unrealized gains (losses) | 634 | ' | 634 | ' | 1,780 |
Available-for-sale securities continuous unrealized loss position [Abstract] | ' | ' | ' | ' | ' |
Number of Securities, 12 months or less | 353 | ' | 353 | ' | 451 |
Number of Securities, Greater than 12 months | 131 | ' | 131 | ' | 53 |
Number of Securities, total | 484 | ' | 484 | ' | 504 |
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract] | ' | ' | ' | ' | ' |
Fair value, 12 months or less | 90,946 | ' | 90,946 | ' | 123,145 |
Fair value, Greater than 12 months | 44,616 | ' | 44,616 | ' | 18,249 |
Fair value, total | 135,562 | ' | 135,562 | ' | 141,394 |
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract] | ' | ' | ' | ' | ' |
Gross unrealized loss, 12 months or less | ' | ' | -2,127 | ' | -3,105 |
Gross unrealized loss, Greater than 12 months | ' | ' | -1,675 | ' | -1,040 |
Gross unrealized loss, total | ' | ' | -3,802 | ' | -4,145 |
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract] | ' | ' | ' | ' | ' |
Gross gains | 798 | 2,043 | 5,399 | 5,695 | ' |
Gross losses | -1,259 | -1,277 | -3,411 | -3,497 | ' |
Net realized gains (losses) | -461 | 766 | 1,988 | 2,198 | ' |
Financial institutions [Member] | ' | ' | ' | ' | ' |
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 20,594 | ' | 20,594 | ' | 18,850 |
Cost or amortized cost | 9,520 | ' | 9,520 | ' | 7,780 |
Gross unrealized gains | 11,096 | ' | 11,096 | ' | 11,171 |
Gross unrealized losses | -22 | ' | -22 | ' | -101 |
Net unrealized gains (losses) | 11,074 | ' | 11,074 | ' | 11,070 |
Industrial & miscellaneous [Member] | ' | ' | ' | ' | ' |
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 139,676 | ' | 139,676 | ' | 126,978 |
Cost or amortized cost | 67,077 | ' | 67,077 | ' | 64,307 |
Gross unrealized gains | 73,467 | ' | 73,467 | ' | 63,009 |
Gross unrealized losses | -868 | ' | -868 | ' | -338 |
Net unrealized gains (losses) | 72,599 | ' | 72,599 | ' | 62,671 |
Total equity securities [Member] | ' | ' | ' | ' | ' |
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 160,270 | ' | 160,270 | ' | 145,828 |
Cost or amortized cost | 76,597 | ' | 76,597 | ' | 72,087 |
Gross unrealized gains | 84,563 | ' | 84,563 | ' | 74,180 |
Gross unrealized losses | -890 | ' | -890 | ' | -439 |
Net unrealized gains (losses) | 83,673 | ' | 83,673 | ' | 73,741 |
Available-for-sale securities continuous unrealized loss position [Abstract] | ' | ' | ' | ' | ' |
Number of Securities, 12 months or less | 30 | ' | 30 | ' | 10 |
Number of Securities, Greater than 12 months | 5 | ' | 5 | ' | 2 |
Number of Securities, total | 35 | ' | 35 | ' | 12 |
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract] | ' | ' | ' | ' | ' |
Fair value, 12 months or less | 9,248 | ' | 9,248 | ' | 1,682 |
Fair value, Greater than 12 months | 1,516 | ' | 1,516 | ' | 1,980 |
Fair value, total | 10,764 | ' | 10,764 | ' | 3,662 |
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract] | ' | ' | ' | ' | ' |
Gross unrealized loss, 12 months or less | ' | ' | -806 | ' | -204 |
Gross unrealized loss, Greater than 12 months | ' | ' | -84 | ' | -235 |
Gross unrealized loss, total | ' | ' | -890 | ' | -439 |
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract] | ' | ' | ' | ' | ' |
Gross gains | 2,529 | 1,233 | 4,682 | 13,838 | ' |
Gross losses | -346 | -358 | -1,057 | -1,767 | ' |
Net realized gains (losses) | 2,183 | 875 | 3,625 | 12,071 | ' |
Total available-for-sale securities [Member] | ' | ' | ' | ' | ' |
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract] | ' | ' | ' | ' | ' |
Fair value | 592,071 | ' | 592,071 | ' | 577,378 |
Cost or amortized cost | 507,764 | ' | 507,764 | ' | 501,857 |
Gross unrealized gains | 88,999 | ' | 88,999 | ' | 80,105 |
Gross unrealized losses | -4,692 | ' | -4,692 | ' | -4,584 |
Net unrealized gains (losses) | $84,307 | ' | $84,307 | ' | $75,521 |