Investments - Unrealized losses (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities
Less than 12 Months, Fair Value	$ 159,074	$ 283,243
Less than 12 Months, Unrealized Losses	(2,987)	(8,501)
12 Months or More, Fair Value	41,489	18,104
12 Months or More, Unrealized Losses	(546)	(261)
Total Fair Value	200,563	301,347
Total Unrealized Losses	(3,533)	(8,762)
U.S. Government agencies
Schedule of Available-for-sale Securities
Less than 12 Months, Fair Value	0	34,586
Less than 12 Months, Unrealized Losses	0	(198)
12 Months or More, Fair Value	10,867	10,438
12 Months or More, Unrealized Losses	(31)	(79)
Total Fair Value	10,867	45,024
Total Unrealized Losses	(31)	(277)
Obligations of states and political subdivisions
Schedule of Available-for-sale Securities
Less than 12 Months, Fair Value	28,805	122,522
Less than 12 Months, Unrealized Losses	(608)	(4,353)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Total Fair Value	28,805	122,522
Total Unrealized Losses	(608)	(4,353)
U.S. Government agencies collateralized by residential mortgage obligations
Schedule of Available-for-sale Securities
Less than 12 Months, Fair Value	86,116	118,719
Less than 12 Months, Unrealized Losses	(1,922)	(3,866)
12 Months or More, Fair Value	30,622	7,666
12 Months or More, Unrealized Losses	(515)	(182)
Total Fair Value	116,738	126,385
Total Unrealized Losses	(2,437)	(4,048)
Private label mortgage backed securities
Schedule of Available-for-sale Securities
Less than 12 Months, Fair Value	36,674
Less than 12 Months, Unrealized Losses	(436)
12 Months or More, Fair Value	0
12 Months or More, Unrealized Losses	0
Total Fair Value	36,674
Total Unrealized Losses	(436)
Other equity securities
Schedule of Available-for-sale Securities
Less than 12 Months, Fair Value	7,479	7,416
Less than 12 Months, Unrealized Losses	(21)	(84)
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Total Fair Value	7,479	7,416
Total Unrealized Losses	$ (21)	$ (84)