Investments Unrealized Losses Less Than and Greater Than 12 Months (Details) $ in Thousands	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 116	$ 127
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	5,340	9,246
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	1,599	2,291
Debt Securities In Continuous Loss Less Than 12 Months Fair Value	230,758	341,677
Debt Securities, Continuous Unrealized Loss Position for Less Than 12 Months	$ 3,705	$ 8,666
Debt Securities In Unrealized Loss Positions Qualitative Disclosure, Number Of Positions, Less Than 12 Months	197	308
Debt Securities In Continuous Loss Position 12 Months Or Longer, Fair Value	$ 14,127	$ 16,905
Debt Securities, Continuous Unrealized Loss Position for Greater Than 12 Months	$ 3,234	$ 2,871
Debt Securities In Unrealized Loss Positions Qualitative Disclosure, Number Of Positions,12 Months Or Greater	22	21
Debt Securities In Continuous Loss Position, Aggregate Fair Value	$ 244,885	$ 358,582
Debt Securities, Gross Unrealized and Unrecognized Losses	$ 6,939	$ 11,537
Debt Securities In Unrealized Loss Positions Qualitative Disclosure, Number Of Positions	219	329
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 138,043	$ 202,788
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,686	$ 3,513
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	112	184
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 9,127	$ 8,018
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1,476	$ 1,509
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	10	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 147,170	$ 210,806
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	$ 3,162	$ 5,022
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	122	192
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 22,373	$ 43,659
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 457	$ 1,562
Number of Held to Maturity Securities In Continuous Loss Position Less Than 12 Months	31	47
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 1,342	$ 509
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 283	$ 37
Number of Held to Maturity Securities In Continuous Loss Position 12 Months or Greater	2	1
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 23,715	$ 44,168
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	$ 740	$ 1,599
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	33	48
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 70,235	$ 91,527
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,561	$ 3,578
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	51	70
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 1,576	$ 6,102
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 615	$ 644
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year	6	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 71,811	$ 97,629
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	$ 2,176	$ 4,222
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	57	78
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 0	$ 3,587
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 12
Number of Held to Maturity Securities In Continuous Loss Position Less Than 12 Months	0	3
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 1,979	$ 2,171
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 859	$ 680
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	$ 1,979	$ 5,758
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	$ 859	$ 692
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	2	5
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 107	$ 116
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	3	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 103	$ 105
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	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 210	$ 221
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	$ 2	$ 2
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	5	6
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 208,385	$ 294,431
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 3,248	$ 7,092
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	166	258
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 10,806	$ 14,225
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 2,092	$ 2,154
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, Continuous Unrealized Loss Position, Fair Value	$ 219,191	$ 308,656
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	$ 5,340	$ 9,246
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	184	276
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 22,373	$ 47,246
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 457	$ 1,574
Number of Held to Maturity Securities In Continuous Loss Position Less Than 12 Months	31	50
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 3,321	$ 2,680
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1,142	$ 717
Number of Held to Maturity Securities In Continuous Loss Position 12 Months or Greater	4	3
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 25,694	$ 49,926
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	$ 1,599	$ 2,291
Held-to-maturity, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	35	53
Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 0	$ 0
Bond Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	8,183	10,160
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 114	$ 108
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	1	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 0
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	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 8,183	$ 10,160
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 114	$ 108
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1	2
Common Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 21	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 2	$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	2	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 17
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, Continuous Unrealized Loss Position, Fair Value	$ 21	$ 0
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 2	$ 17
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	2	1
Redeemable Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 201
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 2
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year		2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		$ 201
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 0	$ 2
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		2
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	8,204	$ 10,361
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 116	$ 110
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year	3	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 17
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, Continuous Unrealized Loss Position, Fair Value	$ 8,204	$ 10,361
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 116	$ 127
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	3	5