Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014 Security Agreement	Jun. 30, 2013	Jun. 30, 2014 Security Agreement	Jun. 30, 2013	Dec. 31, 2013 Security
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Cost or amortized cost	$ 426,178		$ 426,178
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Applicable federal income taxes	(31,979)				(26,432)
Net unrealized gains - net of tax	59,389				49,089
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities, total	356		356		516
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, total	96,053		96,053		145,056
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, total			(3,128)		(4,584)
Available-for-sale securities debt maturities fair value [Abstract]
One year or less, Fair Value	124,351		124,351
Excess of one year to five years, Fair Value	165,938		165,938
Excess of five years to ten years, Fair Value	62,049		62,049
Excess of ten years, Fair Value	8,076		8,076
Contractual maturities, Fair Value	360,414		360,414
Asset-backed securities, Fair Value	69,046		69,046
Total, Fair Value	429,460		429,460
Available-for-sale securities debt maturities amortized cost basis [Abstract]
One year or less, Amortized Cost Basis	124,042		124,042
Excess of one year to five years, Amortized Cost Basis	165,905		165,905
Excess of five years to ten years, Amortized Cost Basis	60,694		60,694
Excess of ten years, Amortized Cost Basis	7,347		7,347
Contractual maturities, Amortized Cost Basis	357,988		357,988
Asset-backed securities, Amortized Cost Basis	68,190		68,190
Cost or amortized cost	426,178		426,178
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Limited partnerships - net gain (loss)	5,200	(1,275)	8,268	2,438
Net realized gains on investments	8,089	719	12,159	15,066
Available for sale securities gain loss activity [Abstract]
Realized net gains on the disposal of securities	2,419	1,554	3,614	10,798
Mark-to-market adjustment	469	195	269	405
Equity in gains of limited partnership investments - realized and unrealized	5,200	(1,275)	8,268	2,438
Write-downs based upon objective criteria	0	(68)	(105)	(74)
Recovery of prior write-downs upon sale or disposal	1	313	113	1,499
Net realized gains on investments	8,089	719	12,159	15,066
Net unrealized gain (loss) on investments	1,649		5,507
Net unrealized gains in limited partnership			12,971
Undistributed earnings of limited partnership, net of taxes	29,768		29,768
Committed funds for bridge loans	64,750		64,750
Number of bridge loan agreements	7		7
U.S. government obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	119,517		119,517		113,389
Cost or amortized cost	119,356		119,356		113,348
Gross unrealized gains	176		176		81
Gross unrealized losses	(15)		(15)		(40)
Net unrealized gains (losses)	161		161		41
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	119,356		119,356		113,348
Residential mortgage-backed securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	7,935		7,935		13,252
Cost or amortized cost	7,574		7,574		12,058
Gross unrealized gains	424		424		1,334
Gross unrealized losses	(63)		(63)		(140)
Net unrealized gains (losses)	361		361		1,194
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	7,574		7,574		12,058
Commercial mortgage-backed securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	26,618		26,618		28,565
Cost or amortized cost	25,878		25,878		28,406
Gross unrealized gains	815		815		308
Gross unrealized losses	(75)		(75)		(149)
Net unrealized gains (losses)	740		740		159
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	25,878		25,878		28,406
States and municipal obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	114,212		114,212		115,250
Cost or amortized cost	113,481		113,481		115,278
Gross unrealized gains	861		861		407
Gross unrealized losses	(130)		(130)		(435)
Net unrealized gains (losses)	731		731		(28)
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	113,481		113,481		115,278
Corporate securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	135,435		135,435		137,215
Cost or amortized cost	134,469		134,469		136,991
Gross unrealized gains	3,426		3,426		3,207
Gross unrealized losses	(2,460)		(2,460)		(2,983)
Net unrealized gains (losses)	966		966		224
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	134,469		134,469		136,991
Foreign government obligations [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	25,743		25,743		23,879
Cost or amortized cost	25,420		25,420		23,689
Gross unrealized gains	471		471		588
Gross unrealized losses	(148)		(148)		(398)
Net unrealized gains (losses)	323		323		190
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	25,420		25,420		23,689
Total fixed maturities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Fair value	429,460		429,460		431,550
Cost or amortized cost	426,178		426,178		429,770
Gross unrealized gains	6,173		6,173		5,925
Gross unrealized losses	(2,891)		(2,891)		(4,145)
Net unrealized gains (losses)	3,282		3,282		1,780
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities Less than 12 months	256		256		451
Number of Securities More than 12 months	86		86		53
Number of Securities, total	342		342		504
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, 12 months or less	61,528		61,528		123,145
Fair value, 12 months or longer	30,389		30,389		18,249
Fair value, total	91,917		91,917		141,394
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, less than 12 months			(1,827)		(3,105)
Gross unrealized loss, 12 months or longer			(1,064)		(1,040)
Gross unrealized loss, total			(2,891)		(4,145)
Available-for-sale securities debt maturities amortized cost basis [Abstract]
Cost or amortized cost	426,178		426,178		429,770
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	2,762	2,233	4,601	3,652
Gross losses	(926)	(883)	(2,152)	(2,220)
Net realized gains	1,836	1,350	2,449	1,432
Financial institutions [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value	20,456		20,456		18,850
Cost or amortized cost	8,565		8,565		7,780
Gross unrealized gains	11,907		11,907		11,171
Gross unrealized losses	(16)		(16)		(101)
Net unrealized gains (losses)	11,891		11,891		11,070
Industrial & miscellaneous [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value	140,470		140,470		126,978
Cost or amortized cost	64,275		64,275		64,307
Gross unrealized gains	76,416		76,416		63,009
Gross unrealized losses	(221)		(221)		(338)
Net unrealized gains (losses)	76,195		76,195		62,671
Total equity securities [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Fair value	160,926		160,926		145,828
Cost or amortized cost	72,840		72,840		72,087
Gross unrealized gains	88,323		88,323		74,180
Gross unrealized losses	(237)		(237)		(439)
Net unrealized gains (losses)	88,086		88,086		73,741
Available-for-sale securities continuous unrealized loss position [Abstract]
Number of Securities Less than 12 months	10		10		10
Number of Securities More than 12 months	4		4		2
Number of Securities, total	14		14		12
Available-for-sale securities continuous unrealized loss position, Fair Value [Abstract]
Fair value, 12 months or less	3,510		3,510		1,682
Fair value, 12 months or longer	626		626		1,980
Fair value, total	4,136		4,136		3,662
Available-for-sale securities continuous unrealized loss position, aggregate losses [Abstract]
Gross unrealized loss, less than 12 months			(185)		(204)
Gross unrealized loss, 12 months or longer			(52)		(235)
Gross unrealized loss, total			(237)		(439)
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Gross gains	1,412	893	2,153	12,605
Gross losses	(359)	(249)	(711)	(1,409)
Net realized gains	1,053	644	1,442	11,196
Total available-for-sale securities [Member]
Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract]
Fair value	590,386		590,386		577,378
Cost or amortized cost	499,018		499,018		501,857
Gross unrealized gains	94,496		94,496		80,105
Gross unrealized losses	(3,128)		(3,128)		(4,584)
Net unrealized gains (losses)	$ 91,368		$ 91,368		$ 75,521