Investments, Securities with Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 2,051	$ 49,633
12 months or longer	42,935	125,778
Total	44,986	175,411
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	5	1,592
12 months or longer	2,707	10,259
Total	2,712	11,851
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	0	0
12 months or longer	10,865	24,786
Total	10,865	24,786
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	0	0
12 months or longer	329	1,061
Total	329	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	2,051	49,633
12 months or longer	32,070	97,012
Total	34,121	146,645
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	5	1,592
12 months or longer	2,378	9,126
Total	$ 2,383	$ 10,718