Investments Unrealized Losses Less Than and Greater Than 12 Months (Details) $ in Thousands	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Debt Securities In Continuous Loss Less Than 12 Months Fair Value	$ 341,677	$ 286,213
Debt Securities Continuous Loss Position Less Than 12 Months Unrealized Losses	$ 8,666	$ 7,220
Number of Debt Securities In Continuous Loss Less Than 12 Months	308	263
Debt Securities In Continuous Loss Position 12 Months Or Longer, Fair Value	$ 16,905	$ 20,638
Debt Securities In Continuous Loss Position 12 Months Or Longer, Unrealized Losses	$ 2,871	$ 3,097
Number of Debt Securities In Continuous Loss Position 12 Months or Longer	21	25
Debt Securities In Continuous Loss Position, Aggregate Fair Value	$ 358,582	$ 306,851
Debt Securities In Continuous Loss Position, Aggregate Unrealized Losses	$ 11,537	$ 10,317
Number of Debt Securities In Continuous Loss Position, Aggregate	329	288
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 210,806	$ 149,495
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	5,022	3,085
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	202,788	136,862
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 3,513	$ 1,474
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	184	129
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 8,018	$ 12,633
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1,509	$ 1,611
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	8	12
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	192	141
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 43,659	$ 74,628
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,562	$ 774
Number of Held to Maturity Securities In Continuous Loss Position Less Than 12 Months	47	59
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 509	$ 2,404
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 37	$ 109
Number of Held to Maturity Securities In Continuous Loss Position 12 Months or Greater	1	5
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 44,168	$ 77,032
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 1,599	$ 883
Number of Held to Maturity Securities In Continuous Loss Position Aggregate	48	64
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 97,629	$ 73,389
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	4,222	4,847
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	91,527	70,081
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 3,578	$ 4,330
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	70	69
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 6,102	$ 3,308
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 644	$ 517
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	8	3
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	78	72
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 3,587	$ 4,585
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 12	$ 641
Number of Held to Maturity Securities In Continuous Loss Position Less Than 12 Months	3	4
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 2,171	$ 2,160
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 680	$ 859
Number of Held to Maturity Securities In Continuous Loss Position 12 Months or Greater	2	2
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 5,758	$ 6,745
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 692	$ 1,500
Number of Held to Maturity Securities In Continuous Loss Position Aggregate	5	6
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 221	$ 190
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	116	57
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1	$ 1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	4	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 105	$ 133
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1	$ 1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	2	3
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	6	5
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 308,656	$ 223,074
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	9,246	7,934
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	294,431	207,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 7,092	$ 5,805
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	258	200
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 14,225	$ 16,074
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 2,154	$ 2,129
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	18	18
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	276	218
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 47,246	$ 79,213
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,574	$ 1,415
Number of Held to Maturity Securities In Continuous Loss Position Less Than 12 Months	50	63
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 2,680	$ 4,564
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 717	$ 968
Number of Held to Maturity Securities In Continuous Loss Position 12 Months or Greater	3	7
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 49,926	$ 83,777
Held-to-maturity Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ 2,291	$ 2,383
Number of Held to Maturity Securities In Continuous Loss Position Aggregate	53	70
Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 0	$ 3,032
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	0	237
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	3,030
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 237
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	0	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	0	1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	0	5
Fixed Income Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 10,160	$ 10,266
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	108	349
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	10,160	10,158
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 108	$ 318
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 108
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 31
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	0	1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	2	3
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 201	$ 102
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	201	101
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 2	$ 1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	2	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	0	1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	2	2
Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 0	$ 43
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	17	22
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	22
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 1
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	0	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 21
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 17	$ 21
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	1	2
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1	4
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 10,361	$ 13,443
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	127	610
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	10,361	13,311
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 110	$ 557
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	4	9
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 132
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 17	$ 53
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	1	5
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	5	14