Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]: Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value (Details) $ in Thousands	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 23,509	$ 92,853
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	119	1,730
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	138,602	268,034
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	2,548	9,846
Debt Securities, Available-for-sale, Unrealized Loss Position	162,111	360,887
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 2,667	$ 11,576
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	6	47
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	81	115
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	87	162
Corporate Debt Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 7,307	$ 46,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	20	1,045
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	57,300	108,738
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,341	4,361
Debt Securities, Available-for-sale, Unrealized Loss Position	64,607	155,726
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,361	5,406
Collateralized Mortgage Backed Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	847
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	37
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	4,095	4,993
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	215
Debt Securities, Available-for-sale, Unrealized Loss Position	4,095	5,840
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	3	252
US Treasury Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	5,433	6,138
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	69	15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	18,135	31,693
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	34	408
Debt Securities, Available-for-sale, Unrealized Loss Position	23,568	37,831
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	103	423
US Government-sponsored Enterprises Debt Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	6,297	6,478
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	111	110
Debt Securities, Available-for-sale, Unrealized Loss Position	6,297	6,478
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	111	110
US States and Political Subdivisions Debt Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	10,769	33,021
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	30	522
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	51,116	113,297
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,053	4,706
Debt Securities, Available-for-sale, Unrealized Loss Position	61,885	146,318
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,083	5,228
Debt Security, Government, Non-US
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	1,659	2,835
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	6	46
Debt Securities, Available-for-sale, Unrealized Loss Position	1,659	2,835
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 6	46
Redeemable Preferred Stock
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months		5,859
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		111
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer		0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Debt Securities, Available-for-sale, Unrealized Loss Position		5,859
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss		$ 111