Investments, Available-for-sale Securities in a Loss Position (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Rate	Dec. 31, 2018 USD ($) Rate
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Estimated Fair Value	$ 126,115	$ 222,581
Less than 12 months, gross unrealized holding losses	1,663	2,502
12 Months or Longer, Estimated Fair Value	73,201	128,301
12 Months or Longer, Gross Unrealized Holding Losses	651	4,366
Total Estimated Fair Value	199,316	350,882
Total Gross Unrealized Holding Losses	$ (2,314)	$ (6,868)
Number of available-for-sale securities in unrealized loss positions	137	317
Number of available-for-sale securities in unrealized loss positions, greater than one year	51	158
Fixed Maturities [Member]
Debt Securities, Available-for-sale [Line Items]
Percentage of securities rated A- or better | Rate	89.00%	86.40%
Other-than-temporary impairment losses	$ 0	$ 0
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Estimated Fair Value	0	0
Less than 12 months, gross unrealized holding losses	0	0
12 Months or Longer, Estimated Fair Value	0	499
12 Months or Longer, Gross Unrealized Holding Losses	0	1
Total Estimated Fair Value	0	499
Total Gross Unrealized Holding Losses	0	(1)
Obligations of States, Municipalities and Political Subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Estimated Fair Value	28,997	42,718
Less than 12 months, gross unrealized holding losses	961	440
12 Months or Longer, Estimated Fair Value	254	34,326
12 Months or Longer, Gross Unrealized Holding Losses	0	854
Total Estimated Fair Value	29,251	77,044
Total Gross Unrealized Holding Losses	(961)	(1,294)
Corporate and Other Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Estimated Fair Value	22,409	62,045
Less than 12 months, gross unrealized holding losses	251	890
12 Months or Longer, Estimated Fair Value	1,509	12,092
12 Months or Longer, Gross Unrealized Holding Losses	4	511
Total Estimated Fair Value	23,918	74,137
Total Gross Unrealized Holding Losses	(255)	(1,401)
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Estimated Fair Value	37,723	93,247
Less than 12 months, gross unrealized holding losses	303	1,017
12 Months or Longer, Estimated Fair Value	46,623	25,746
12 Months or Longer, Gross Unrealized Holding Losses	407	505
Total Estimated Fair Value	84,346	118,993
Total Gross Unrealized Holding Losses	(710)	(1,522)
Residential Mortgage-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months, Estimated Fair Value	36,986	24,571
Less than 12 months, gross unrealized holding losses	148	155
12 Months or Longer, Estimated Fair Value	24,815	55,638
12 Months or Longer, Gross Unrealized Holding Losses	240	2,495
Total Estimated Fair Value	61,801	80,209
Total Gross Unrealized Holding Losses	$ (388)	$ (2,650)