Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013 Security Agreement	Sep. 30, 2012	Sep. 30, 2013 Security Agreement	Sep. 30, 2012	Dec. 31, 2012 Security
Schedule of Available-For-Sale Securities [Line Items]
Applicable federal income taxes	$ (21,481)				$ (19,098)
Net unrealized gains - net of tax	39,891				35,467
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities, total	576		576		259
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, total	136,101		136,101		123,485
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, total	(4,811)		(4,811)		(2,937)
Available-for-sale securities debt maturities fair value [Abstract]
One year or less, Fair Value	66,609		66,609
Excess of one year to five years, Fair Value	233,763		233,763
Excess of five years to ten years, Fair Value	43,522		43,522
Excess of ten years, Fair Value	6,086		6,086
Contractual maturities, Fair Value	349,980		349,980
Asset-backed securities, Fair Value	69,774		69,774
Total, Fair Value	419,754		419,754
Available-for-sale securities debt maturities amortized cost basis [Abstract]
One year or less, Amortized Cost Basis	66,049		66,049
Excess of one year to five years, Amortized Cost Basis	233,951		233,951
Excess of five years to ten years, Amortized Cost Basis	42,931		42,931
Excess of ten years, Amortized Cost Basis	5,829		5,829
Contractual maturities, Amortized Cost Basis	348,760		348,760
Asset-backed securities, Amortized Cost Basis	68,941		68,941
Total, Amortized cost basis	417,701		417,701
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Limited partnerships - net gain (loss)	(211)	6,295	2,227	6,832
Totals	1,430	8,781	16,496	8,709
Available for sale securities gain loss activity [Abstract]
Realized net gains on the disposal of securities	1,090	1,659	11,888	1,454
Mark-to-market adjustment	342	456	747	144
Equity in gains (losses) of limited partnership investments - realized and unrealized	(211)	6,295	2,227	6,832
Write-downs based upon objective criteria	(4)	(411)	(78)	(756)
Recovery of prior write-downs upon sale or disposal	213	782	1,712	1,035
Totals	1,430	8,781	16,496	8,709
Net unrealized gain (loss) on investments	548		795
Net unrealized gains in limited partnership			3,645
Undistributed earnings of limited partnership, net of taxes	20,814		20,814
Committed funds for bridge loans	8,500		8,500
Number of bridge loan agreements	2		2
U.S. government obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	106,136		106,136		70,742
Cost or Amortized Cost	106,045		106,045		70,720
Gross Unrealized Gains	104		104		43
Gross Unrealized Losses	(13)		(13)		(21)
Net Unrealized Gains (Losses)	91		91		22
Residential mortgage-backed securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	14,654		14,654		25,040
Cost or Amortized Cost	13,534		13,534		23,954
Gross Unrealized Gains	1,291		1,291		1,218
Gross Unrealized Losses	(171)		(171)		(132)
Net Unrealized Gains (Losses)	1,120		1,120		1,086
Commercial mortgage-backed securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	27,014		27,014		11,828
Cost or Amortized Cost	27,077		27,077		11,006
Gross Unrealized Gains	214		214		849
Gross Unrealized Losses	(277)		(277)		(27)
Net Unrealized Gains (Losses)	(63)		(63)		822
States and municipal obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	111,419		111,419		194,865
Cost or Amortized Cost	111,321		111,321		194,258
Gross Unrealized Gains	481		481		757
Gross Unrealized Losses	(383)		(383)		(150)
Net Unrealized Gains (Losses)	98		98		607
Corporate securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	135,355		135,355		120,596
Cost or Amortized Cost	134,778		134,778		118,574
Gross Unrealized Gains	2,788		2,788		2,923
Gross Unrealized Losses	(2,211)		(2,211)		(901)
Net Unrealized Gains (Losses)	577		577		2,022
Foreign government obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	25,176		25,176		22,598
Cost or Amortized Cost	24,946		24,946		22,047
Gross Unrealized Gains	479		479		602
Gross Unrealized Losses	(249)		(249)		(51)
Net Unrealized Gains (Losses)	230		230		551
Total fixed maturities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	419,754		419,754		445,669
Cost or Amortized Cost	417,701		417,701		440,559
Gross Unrealized Gains	5,357		5,357		6,392
Gross Unrealized Losses	(3,304)		(3,304)		(1,282)
Net Unrealized Gains (Losses)	2,053		2,053		5,110
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities Less than 12 months	508		508		170
Number of Securities More than 12 months	43		43		58
Number of Securities, total	551		551		228
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, 12 months or less	109,803		109,803		90,607
Fair value, 12 months or longer	15,170		15,170		19,283
Fair value, total	124,973		124,973		109,890
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, less than 12 months	(2,573)		(2,573)		(483)
Gross unrealized loss, 12 months or longer	(731)		(731)		(799)
Gross unrealized loss, total	(3,304)		(3,304)		(1,282)
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	2,043	1,508	5,695	2,850
Gross losses	(1,277)	(801)	(3,497)	(2,952)
Net realized gains (losses)	766	707	2,198	(102)
Financial institutions [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	16,085		16,085		12,394
Cost or Amortized Cost	7,274		7,274		5,925
Gross Unrealized Gains	9,015		9,015		6,542
Gross Unrealized Losses	(204)		(204)		(73)
Net Unrealized Gains (Losses)	8,811		8,811		6,469
Industrial & Miscellaneous [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	113,361		113,361		95,188
Cost or Amortized Cost	62,853		62,853		52,202
Gross Unrealized Gains	51,811		51,811		44,568
Gross Unrealized Losses	(1,303)		(1,303)		(1,582)
Net Unrealized Gains (Losses)	50,508		50,508		42,986
Total equity securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	129,446		129,446		107,582
Cost or Amortized Cost	70,127		70,127		58,127
Gross Unrealized Gains	60,826		60,826		51,110
Gross Unrealized Losses	(1,507)		(1,507)		(1,655)
Net Unrealized Gains (Losses)	59,319		59,319		49,455
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities Less than 12 months	21		21		20
Number of Securities More than 12 months	4		4		11
Number of Securities, total	25		25		31
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, 12 months or less	8,355		8,355		6,955
Fair value, 12 months or longer	2,773		2,773		6,640
Fair value, total	11,128		11,128		13,595
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, less than 12 months	(1,341)		(1,341)		(842)
Gross unrealized loss, 12 months or longer	(166)		(166)		(813)
Gross unrealized loss, total	(1,507)		(1,507)		(1,655)
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	1,233	2,132	13,838	2,807
Gross losses	(358)	(353)	(1,767)	(828)
Net realized gains (losses)	875	1,779	12,071	1,979
Total available-for-sale securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	549,200		549,200		553,251
Cost or Amortized Cost	487,828		487,828		498,686
Gross Unrealized Gains	66,183		66,183		57,502
Gross Unrealized Losses	(4,811)		(4,811)		(2,937)
Net Unrealized Gains (Losses)	$ 61,372		$ 61,372		$ 54,565