Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014 Security Agreement	Mar. 31, 2013	Dec. 31, 2013 Security
Schedule of Available-For-Sale Securities [Line Items]
Applicable federal income taxes	$ (29,224)		$ (26,432)
Net unrealized gains - net of tax	54,272		49,089
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities, total	451		516
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, total	133,217		145,056
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, total	(3,591)		(4,584)
Available-for-sale securities debt maturities fair value [Abstract]
One year or less, Fair Value	98,307
Excess of one year to five years, Fair Value	193,827
Excess of five years to ten years, Fair Value	56,991
Excess of ten years, Fair Value	7,891
Contractual maturities, Fair Value	357,016
Asset-backed securities, Fair Value	77,026
Total, Fair Value	434,042
Available-for-sale securities debt maturities amortized cost basis [Abstract]
One year or less, Amortized Cost Basis	98,690
Excess of one year to five years, Amortized Cost Basis	193,119
Excess of five years to ten years, Amortized Cost Basis	56,364
Excess of ten years, Amortized Cost Basis	7,232
Contractual maturities, Amortized Cost Basis	355,405
Asset-backed securities, Amortized Cost Basis	75,551
Total, Amortized cost basis	430,956
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Limited partnerships - net gain	3,068	3,713
Totals	4,070	14,347
Available for sale securities gain loss activity [Abstract]
Realized net gains on the disposal of securities	1,195	9,244
Mark-to-market adjustment	(200)	210
Equity in gains of limited partnership investments - realized and unrealized	3,068	3,713
Write-downs based upon objective criteria	(105)	(6)
Recovery of prior write-downs upon sale or disposal	112	1,186
Totals	4,070	14,347
Net unrealized gain (loss) on investments	3,859
Net unrealized gains in limited partnership	11,322
Undistributed earnings of limited partnership, net of taxes	26,455
Committed funds for bridge loans	20,000
Number of bridge loan agreements	3
U.S. government obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	121,426		113,389
Cost or Amortized Cost	121,413		113,348
Gross Unrealized Gains	117		81
Gross Unrealized Losses	(104)		(40)
Net Unrealized Gains (Losses)	13		41
Residential mortgage-backed securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	16,741		13,252
Cost or Amortized Cost	15,302		12,058
Gross Unrealized Gains	1,520		1,334
Gross Unrealized Losses	(81)		(140)
Net Unrealized Gains (Losses)	1,439		1,194
Commercial mortgage-backed securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	25,561		28,565
Cost or Amortized Cost	25,217		28,406
Gross Unrealized Gains	479		308
Gross Unrealized Losses	(135)		(149)
Net Unrealized Gains (Losses)	344		159
States and municipal obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	115,378		115,250
Cost or Amortized Cost	115,054		115,278
Gross Unrealized Gains	617		407
Gross Unrealized Losses	(293)		(435)
Net Unrealized Gains (Losses)	324		(28)
Corporate securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	127,715		137,215
Cost or Amortized Cost	126,937		136,991
Gross Unrealized Gains	3,255		3,207
Gross Unrealized Losses	(2,477)		(2,983)
Net Unrealized Gains (Losses)	778		224
Foreign government obligations [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	27,221		23,879
Cost or Amortized Cost	27,033		23,689
Gross Unrealized Gains	467		588
Gross Unrealized Losses	(279)		(398)
Net Unrealized Gains (Losses)	188		190
Total fixed maturities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	434,042		431,550
Cost or Amortized Cost	430,956		429,770
Gross Unrealized Gains	6,455		5,925
Gross Unrealized Losses	(3,369)		(4,145)
Net Unrealized Gains (Losses)	3,086		1,780
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities Less than 12 months	369		451
Number of Securities More than 12 months	69		53
Number of Securities, total	438		504
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, 12 months or less	114,779		123,145
Fair value, 12 months or longer	16,018		18,249
Fair value, total	130,797		141,394
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, less than 12 months	(2,339)		(3,105)
Gross unrealized loss, 12 months or longer	(1,030)		(1,040)
Gross unrealized loss, total	(3,369)		(4,145)
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	1,839	1,419
Gross losses	(1,226)	(1,337)
Net realized gains	613	82
Financial institutions [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	19,376		18,850
Cost or Amortized Cost	7,770		7,780
Gross Unrealized Gains	11,606		11,171
Gross Unrealized Losses	0		(101)
Net Unrealized Gains (Losses)	11,606		11,070
Industrial & Miscellaneous [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	133,453		126,978
Cost or Amortized Cost	64,649		64,307
Gross Unrealized Gains	69,026		63,009
Gross Unrealized Losses	(222)		(338)
Net Unrealized Gains (Losses)	68,804		62,671
Total equity securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	152,829		145,828
Cost or Amortized Cost	72,419		72,087
Gross Unrealized Gains	80,632		74,180
Gross Unrealized Losses	(222)		(439)
Net Unrealized Gains (Losses)	80,410		73,741
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities Less than 12 months	12		10
Number of Securities More than 12 months	1		2
Number of Securities, total	13		12
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, 12 months or less	2,401		1,682
Fair value, 12 months or longer	19		1,980
Fair value, total	2,420		3,662
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, less than 12 months	(221)		(204)
Gross unrealized loss, 12 months or longer	(1)		(235)
Gross unrealized loss, total	(222)		(439)
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	741	11,712
Gross losses	(352)	(1,160)
Net realized gains	389	10,552
Total available-for-sale securities [Member]
Schedule of Available-For-Sale Securities [Line Items]
Fair Value	586,871		577,378
Cost or Amortized Cost	503,375		501,857
Gross Unrealized Gains	87,087		80,105
Gross Unrealized Losses	(3,591)		(4,584)
Net Unrealized Gains (Losses)	$ 83,496		$ 75,521