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	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 21,839	$ 92,853
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	60	1,730
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	112,771	268,034
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,964	9,846
Debt Securities, Available-for-sale, Unrealized Loss Position	134,610	360,887
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 2,024	$ 11,576
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions	14	47
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions	48	115
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	62	162
Corporate Debt Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 7,050	$ 46,988
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	13	1,045
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	44,766	108,738
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,094	4,361
Debt Securities, Available-for-sale, Unrealized Loss Position	51,816	155,726
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1,107	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	5	4,993
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	215
Debt Securities, Available-for-sale, Unrealized Loss Position	5	5,840
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	0	252
US Treasury Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	0	6,138
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	15
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	23,621	31,693
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	69	408
Debt Securities, Available-for-sale, Unrealized Loss Position	23,621	37,831
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	69	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	6,203	6,478
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	114	110
Debt Securities, Available-for-sale, Unrealized Loss Position	6,203	6,478
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	114	110
US States and Political Subdivisions Debt Securities
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	14,789	33,021
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	47	522
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	36,544	113,297
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	684	4,706
Debt Securities, Available-for-sale, Unrealized Loss Position	51,333	146,318
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	731	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	1,632	2,835
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	3	46
Debt Securities, Available-for-sale, Unrealized Loss Position	1,632	2,835
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ 3	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