Investments Unrealized Losses Less Than and Greater Than 12 Months (Details) $ in Thousands	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 125,756	$ 475,919
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 1,261	$ 9,727
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	133	442
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 5,721	$ 43,925
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 294	$ 1,585
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	14	58
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 131,477	$ 519,844
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 1,555	$ 11,312
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	147	500
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 24,064	$ 227,132
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 163	$ 883
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	24	233
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 1,961	$ 33,891
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 77	$ 607
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	6	46
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 26,025	$ 261,023
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 240	$ 1,490
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	30	279
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 62,897	$ 230,030
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 918	$ 8,770
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	69	191
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 3,669	$ 9,936
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 216	$ 976
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	5	8
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 66,566	$ 239,966
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 1,134	$ 9,746
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	74	199
Commercial Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,100	$ 14,992
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 5	$ 66
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	2	11
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,100	$ 14,992
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 5	$ 66
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	2	11
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 1,656	$ 18
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 65	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	11	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 91	$ 98
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 1	$ 2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	3	4
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 1,747	$ 116
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 66	$ 2
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	14	7
Asset-backed Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 36,039	$ 3,747
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 110	$ 8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	27	4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	$ 36,039	$ 3,747
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	$ 110	$ 8
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	27	4

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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