Investments - Available-for-sale Securities in Unrealized Loss Positions (Details) $ in Thousands	Sep. 30, 2017 USD ($) security	Dec. 31, 2016 USD ($) security
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	107	201
Greater than 12 months, number of issues | security	19	15
Total Number of Issues | security	126	216
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 52,593	$ 62,307
Greater than 12 months, fair value	5,146	4,341
Total Fair Value	57,739	66,648
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(780)	(1,260)
Greater than 12 months, unrealized losses	(110)	(36)
Total Unrealized losses	$ (890)	$ (1,296)
Total fixed maturity securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	88	125
Greater than 12 months, number of issues | security	18	13
Total Number of Issues | security	106	138
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 51,506	$ 59,835
Greater than 12 months, fair value	5,113	4,275
Total Fair Value	56,619	64,110
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(639)	(1,199)
Greater than 12 months, unrealized losses	(99)	(27)
Total Unrealized losses	$ (738)	$ (1,226)
U.S. Government obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	10	15
Greater than 12 months, number of issues | security	4	0
Total Number of Issues | security	14	15
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 6,177	$ 4,539
Greater than 12 months, fair value	914	0
Total Fair Value	7,091	4,539
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(37)	(36)
Greater than 12 months, unrealized losses	(6)	0
Total Unrealized losses	$ (43)	$ (36)
State and local government
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	23	29
Greater than 12 months, number of issues | security	3	1
Total Number of Issues | security	26	30
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 6,108	$ 8,217
Greater than 12 months, fair value	506	104
Total Fair Value	6,614	8,321
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(35)	(202)
Greater than 12 months, unrealized losses	(18)	(3)
Total Unrealized losses	$ (53)	$ (205)
Corporate debt
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	13	22
Greater than 12 months, number of issues | security	5	7
Total Number of Issues | security	18	29
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 7,568	$ 9,031
Greater than 12 months, fair value	2,037	3,369
Total Fair Value	9,605	12,400
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(143)	(239)
Greater than 12 months, unrealized losses	(19)	(15)
Total Unrealized losses	$ (162)	$ (254)
Commercial mortgage-backed and other asset-backed
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	42	59
Greater than 12 months, number of issues | security	6	5
Total Number of Issues | security	48	64
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 31,653	$ 38,048
Greater than 12 months, fair value	1,656	802
Total Fair Value	33,309	38,850
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(424)	(722)
Greater than 12 months, unrealized losses	(56)	(9)
Total Unrealized losses	$ (480)	$ (731)
Total equity securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	19	76
Greater than 12 months, number of issues | security	1	2
Total Number of Issues | security	20	78
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 1,087	$ 2,472
Greater than 12 months, fair value	33	66
Total Fair Value	1,120	2,538
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(141)	(61)
Greater than 12 months, unrealized losses	(11)	(9)
Total Unrealized losses	$ (152)	$ (70)
Common stocks
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Less than 12 months, number of issues | security	19	76
Greater than 12 months, number of issues | security	1	2
Total Number of Issues | security	20	78
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than 12 months, fair value	$ 1,087	$ 2,472
Greater than 12 months, fair value	33	66
Total Fair Value	1,120	2,538
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]
Less than 12 months, unrealized losses	(141)	(61)
Greater than 12 months, unrealized losses	(11)	(9)
Total Unrealized losses	$ (152)	$ (70)