Investments Gross Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 902,939		$ 902,939		$ 860,473
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	36,098		36,098		30,441
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	5,340		5,340		9,246
Available-for-sale Securities, Debt Securities	933,697		933,697		881,668
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	241,644		241,644		247,004
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	8,671		8,671		7,832
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	1,599		1,599		2,291
Held-to-maturity Securities, Fair Value	248,716		248,716		252,545
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0	$ 0	17	$ 2,300
Total Fixed Maturity Securities, Amortized Cost	1,144,583		1,144,583		1,107,477
Debt Securities, Accumulative Gross Unrealized and Unrecognized Gains	44,769		44,769		38,273
Debt Securities, Accumulated Gross Unrealized and Unrecognized Losses	6,939		6,939		11,537
Total Fixed Maturity Securities, Fair Value	1,182,413		1,182,413		1,134,213
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	15,620		15,620		17,765
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	639		639		521
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	116		116		127
Available-for-sale Securities, Equity Securities	16,143		16,143		18,159
Equity Securities [Member]
Held-to-maturity Securities [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net			0
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	116		116		127
US Treasury Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	9,895		9,895		9,929
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2,249		2,249		2,261
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	12,144		12,144		12,190
US Government Agencies Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	3,582		3,582		7,639
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	966		966		863
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	4,548		4,548		8,502
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities					2,003
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain					28
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss					0
Held-to-maturity Securities, Fair Value					2,031
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	564,289		564,289		563,279
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	17,400		17,400		15,017
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	3,162		3,162		5,022
Available-for-sale Securities, Debt Securities	578,527		578,527		573,274
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	220,674		220,674		223,966
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	7,819		7,819		6,916
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	740		740		1,599
Held-to-maturity Securities, Fair Value	227,753		227,753		229,283
Foreign Government Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	103		103		103
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	22		22		23
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	125		125		126
Corporate Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	323,014		323,014		277,226
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	15,308		15,308		12,095
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2,176		2,176		4,222
Available-for-sale Securities, Debt Securities	336,146		336,146		285,099
Held-to-maturity Securities [Abstract]
Held-to-maturity Securities	20,970		20,970		21,035
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	852		852		888
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	859		859		692
Held-to-maturity Securities, Fair Value	20,963		20,963		21,231
Commercial Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	8		8		50
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		1
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Debt Securities	8		8		51
Residential Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	2,048		2,048		2,247
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	153		153		181
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2		2		2
Available-for-sale Securities, Debt Securities	2,199		2,199		2,426
Short-term Investments [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis					508
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax					0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax					0
Available-for-sale Securities, Debt Securities					508
Stock Mutual Funds [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	2,867		2,867		2,867
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	211		211		79
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		0
Available-for-sale Securities, Equity Securities	3,078		3,078		2,946
Bond Mutual Funds [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	12,071		12,071		14,040
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	377		377		265
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	114		114		108
Available-for-sale Securities, Equity Securities	12,334		12,334		14,197
Common Stock [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	22		22		39
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	0		0		3
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	2		2		17
Available-for-sale Securities, Equity Securities	20		20		25
Redeemable Preferred Stock [Member]
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale Equity Securities, Amortized Cost Basis	660		660		819
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	51		51		174
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0		0		2
Available-for-sale Securities, Equity Securities	$ 711		$ 711		$ 991
Available-for-sale Securities [Member]
Held-to-maturity Securities [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net				$ 0