Investments, Securities with Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	$ 82,616	$ 91,645
12 months or longer	20,538	20,587
Total	103,154	112,232
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	2,679	2,985
12 months or longer	2,531	2,556
Total	5,210	5,541
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	20,307	23,494
12 months or longer	0	0
Total	20,307	23,494
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	513	553
12 months or longer	0	0
Total	513	553
Obligations of States and Political Subdivisions [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	7,869	8,747
12 months or longer	0	0
Total	7,869	8,747
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	184	308
12 months or longer	0	0
Total	184	308
Corporate Securities [Member]
Available-for-sale securities, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months	54,440	59,404
12 months or longer	20,538	20,587
Total	74,978	79,991
Available-for-sale Securities, Continuous Unrealized Loss Position, Unrealized Losses [Abstract]
Less than 12 months	1,982	2,124
12 months or longer	2,531	2,556
Total	$ 4,513	$ 4,680