Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	$ 599,941	$ 589,770
Other investments:
Contributions made to the funds	928	1,123	$ 2,907
Distributions received from the funds	26,735	28,613	$ 29,054
Fair value measurements on a recurring basis
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	599,941	589,770
Total	604,467	597,353
Fair value measurements on a recurring basis | Fixed maturities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	587,209	564,540
Fair value measurements on a recurring basis | States & political subdivisions
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	231,847	231,134
Fair value measurements on a recurring basis | Corporate debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	250,333	234,040
Fair value measurements on a recurring basis | Residential mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	13,513	8,375
Fair value measurements on a recurring basis | Commercial mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	37,571	51,255
Fair value measurements on a recurring basis | Collateralized debt obligations
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	51,745	32,932
Fair value measurements on a recurring basis | Other debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	2,200	6,804
Fair value measurements on a recurring basis | Nonredeemable preferred stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities		12,541
Fair value measurements on a recurring basis | Common stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	12,732	12,689
Fair value measurements on a recurring basis | Real estate
Consolidated fair value measurements on a recurring basis by asset class and level of input
Other investments	4,526	7,583
Fair value measurements on a recurring basis | Level 1
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	12,732	14,757
Total	12,732	14,757
Fair value measurements on a recurring basis | Level 1 | Fixed maturities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | States & political subdivisions
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Corporate debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Residential mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Commercial mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Collateralized debt obligations
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Other debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 1 | Nonredeemable preferred stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities		2,068
Fair value measurements on a recurring basis | Level 1 | Common stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	12,732	12,689
Fair value measurements on a recurring basis | Level 2
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	578,563	575,013
Total	578,563	575,013
Fair value measurements on a recurring basis | Level 2 | Fixed maturities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	578,563	564,540
Fair value measurements on a recurring basis | Level 2 | States & political subdivisions
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	231,847	231,134
Fair value measurements on a recurring basis | Level 2 | Corporate debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	250,264	234,040
Fair value measurements on a recurring basis | Level 2 | Residential mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	13,513	8,375
Fair value measurements on a recurring basis | Level 2 | Commercial mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	37,571	51,255
Fair value measurements on a recurring basis | Level 2 | Collateralized debt obligations
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	43,168	32,932
Fair value measurements on a recurring basis | Level 2 | Other debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	2,200	6,804
Fair value measurements on a recurring basis | Level 2 | Nonredeemable preferred stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities		10,473
Fair value measurements on a recurring basis | Level 2 | Common stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 3
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	8,646	0
Total	8,646	0
Fair value measurements on a recurring basis | Level 3 | Fixed maturities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	8,646	0
Fair value measurements on a recurring basis | Level 3 | States & political subdivisions
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 3 | Corporate debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	69	0
Fair value measurements on a recurring basis | Level 3 | Residential mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 3 | Commercial mortgage-backed securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 3 | Collateralized debt obligations
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	8,577	0
Fair value measurements on a recurring basis | Level 3 | Other debt securities
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 3 | Nonredeemable preferred stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities		0
Fair value measurements on a recurring basis | Level 3 | Common stock
Consolidated fair value measurements on a recurring basis by asset class and level of input
Available-for-sale securities	0	0
Fair value measurements on a recurring basis | Level 3 | Real estate
Other investments:
Contributions made to the funds	0	0
Distributions received from the funds	3,500	12,900
Unfunded commitments	$ 600	$ 600
Fair value measurements on a recurring basis | Level 3 | Real estate | Minimum
Other investments:
Underlying assets, liquidation period from inception of fund (in years)	5 years	5 years
Fair value measurements on a recurring basis | Level 3 | Real estate | Maximum
Other investments:
Underlying assets, liquidation period from inception of fund (in years)	10 years	10 years