Investments Gross Unrealized Gains and Losses (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 826,271,000		$ 826,271,000		$ 714,137,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	52,202,000		52,202,000		29,445,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	3,256,000		3,256,000		7,934,000
Available-for-sale Securities, Debt Securities	875,217,000		875,217,000		735,648,000
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	251,637,000		251,637,000		259,953,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	13,612,000		13,612,000		7,396,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	1,073,000		1,073,000		2,383,000
Held-to-maturity Securities, Fair Value	264,176,000		264,176,000		264,966,000
Total Fixed maturity securities, Amortized Cost	1,077,908,000		1,077,908,000		974,090,000
Debt Securities, Accumulative Gross Unrealized and Unrecognized Gains	65,814,000		65,814,000		36,841,000
Debt Securities, Accumulated Gross Unrealized and Unrecognized Losses	4,329,000		4,329,000		10,317,000
Total Fixed Maturity Securities, Fair Value	1,139,393,000		1,139,393,000		1,000,614,000
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	22,577,000		22,577,000		23,727,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	789,000		789,000		321,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	19,000		19,000		610,000
Available-for-sale Securities, Equity Securities	23,347,000		23,347,000		23,438,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0.0	$ 0	2.3	$ 2.4
US Treasury Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	9,946,000		9,946,000		9,995,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,968,000		2,968,000		2,597,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	12,914,000		12,914,000		12,592,000
US Government Agencies Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	7,670,000		7,670,000		19,676,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,302,000		1,302,000		1,104,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	8,972,000		8,972,000		20,780,000
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	2,005,000		2,005,000		2,010,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	57,000		57,000		110,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0		0		0
Held-to-maturity Securities, Fair Value	2,062,000		2,062,000		2,120,000
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	528,607,000		528,607,000		470,319,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	27,241,000		27,241,000		15,815,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	1,179,000		1,179,000		3,085,000
Available-for-sale Securities, Debt Securities	554,669,000		554,669,000		483,049,000
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	228,564,000		228,564,000		236,776,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	12,515,000		12,515,000		6,756,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	539,000		539,000		883,000
Held-to-maturity Securities, Fair Value	240,540,000		240,540,000		242,649,000
Foreign Government Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	103,000		103,000		104,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	29,000		29,000		27,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	132,000		132,000		131,000
Corporate Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	277,550,000		277,550,000		211,245,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	20,447,000		20,447,000		9,683,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2,075,000		2,075,000		4,847,000
Available-for-sale Securities, Debt Securities	295,922,000		295,922,000		216,081,000
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	21,068,000		21,068,000		21,167,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	1,040,000		1,040,000		530,000
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	534,000		534,000		1,500,000
Held-to-maturity Securities, Fair Value	21,574,000		21,574,000		20,197,000
Commercial Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	73,000		73,000		140,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,000		2,000		5,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	75,000		75,000		145,000
Residential Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	2,322,000		2,322,000		2,658,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	213,000		213,000		214,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2,000		2,000		2,000
Available-for-sale Securities, Debt Securities	2,533,000		2,533,000		2,870,000
Short-term Investments [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	514,000		514,000		251,000
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	514,000		514,000		251,000
Stock Mutual Funds [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax					237,000
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	2,866,000		2,866,000		3,270,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	57,000		57,000		0
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		237,000
Available-for-sale Securities, Equity Securities	2,923,000		2,923,000		3,033,000
Bond Mutual Funds [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2,000		2,000		349,000
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	18,451,000		18,451,000		18,798,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	521,000		521,000		55,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	2,000		2,000		349,000
Available-for-sale Securities, Equity Securities	18,970,000		18,970,000		18,504,000
Common Stock [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	17,000		17,000		22,000
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	39,000		39,000		65,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	2,000		2,000		0
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	17,000		17,000		22,000
Available-for-sale Securities, Equity Securities	24,000		24,000		43,000
Preferred Stock [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax					2,000
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	1,221,000		1,221,000		1,594,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	209,000		209,000		266,000
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		2,000
Available-for-sale Securities, Equity Securities	$ 1,430,000		$ 1,430,000		$ 1,858,000