Investments Gross Unrealized Gains and Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 935,977	$ 860,473
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	41,729	30,441
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	3,097	9,246
Available-for-sale Securities	974,609	881,668
Held-to-maturity Securities [Abstract]
Fixed maturities held-to-maturity, at amortized cost	233,961	247,004
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	8,703	7,832
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	1,287	2,291
Fixed maturities held-to-maturity, fair value	241,377	252,545
Total Fixed maturity securities, Amortized Cost	1,169,938
Total Fixed Maturity Securities, Fair Value	1,215,986
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale equity securities, amortized cost basis	15,289	17,765
US Treasury Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	9,860	9,929
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,948	2,261
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	11,808	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	3,570	7,639
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	926	863
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	4,496	8,502
Held-to-maturity Securities [Abstract]
Fixed maturities held-to-maturity, at amortized cost		2,003
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain		28
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss		0
Fixed maturities held-to-maturity, 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	550,536	563,279
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	18,507	15,017
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,540	5,022
Available-for-sale Securities	567,503	573,274
Held-to-maturity Securities [Abstract]
Fixed maturities held-to-maturity, at amortized cost	213,054	223,966
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	7,585	6,916
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	629	1,599
Fixed maturities held-to-maturity, fair value	220,010	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
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	18	23
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	121	126
Corporate Debt Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	370,043	277,226
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	20,212	12,095
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	1,552	4,222
Available-for-sale Securities	388,703	285,099
Held-to-maturity Securities [Abstract]
Fixed maturities held-to-maturity, at amortized cost	20,907	21,035
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	1,118	888
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	658	692
Fixed maturities held-to-maturity, fair value	21,367	21,231
Commercial Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis		50
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax		0
Available-for-sale Securities		51
Residential Mortgage Backed Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Debt Securities, Amortized Cost Basis	1,865	2,247
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	118	181
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	5	2
Available-for-sale Securities	1,978	2,426
Debt Securities [Member]
Held-to-maturity Securities [Abstract]
Total Fixed maturity securities, Amortized Cost	1,169,938	1,107,477
Debt Securities, Accumulative Gross Unrealized and Unrecognized Gains	50,432	38,273
Debt Securities, Accumulated Gross Unrealized and Unrecognized Losses	4,384	11,537
Total Fixed Maturity Securities, Fair Value	1,215,986	1,134,213
Stock Mutual Funds [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities	3,217	2,946
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale equity securities, amortized cost basis	2,867	2,867
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	350	79
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Bond Mutual Funds [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities	12,367	14,197
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale equity securities, amortized cost basis	11,880	14,040
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	487	265
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0	108
Common Stock [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities	24	25
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale equity securities, amortized cost basis	22	39
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	2	3
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	0	17
Preferred Stock [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities	556	991
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale equity securities, amortized cost basis	520	819
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	42	174
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	6	2
Equity Securities [Member]
Available-for-sale Debt Securities, Amortized Cost Basis [Abstract]
Available-for-sale Securities	16,164	18,159
Available-for-sale Equity Securities, Amortized Cost Basis [Abstract]
Available-for-sale equity securities, amortized cost basis	15,289	17,765
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	881	521
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 6	$ 127