Investments, Securities with Continuous Unrealized Loss Position (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) Securities	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Securities	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) Securities
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 23,811		$ 23,811		$ 49,633
12 months or longer	15,119		15,119		125,778
Total	38,930		38,930		175,411
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	65		65		1,592
12 months or longer	308		308		10,259
Total	373		373		$ 11,851
Gross OTTI losses charged to realized gains	$ 0	$ 0	$ 0	$ 0
Number of securities in unrealized loss position | Securities	24		24		140
U.S. Treasury Securities and Obligations of U.S. Government Agencies and Authorities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 1,020		$ 1,020		$ 0
12 months or longer	7,689		7,689		24,786
Total	8,709		8,709		24,786
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	4		4		0
12 months or longer	118		118		1,061
Total	122		122		1,061
Obligations of States and Political Subdivisions [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months					0
12 months or longer					3,980
Total					3,980
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months					0
12 months or longer					72
Total					72
Corporate Securities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	22,791		22,791		49,633
12 months or longer	7,430		7,430		97,012
Total	30,221		30,221		146,645
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	61		61		1,592
12 months or longer	190		190		9,126
Total	$ 251		$ 251		$ 10,718