Fair Value Disclosures [Text Block]: Fair Value, Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Debt Securities	$ 441,912	$ 449,487
Available-for-sale Securities, Equity Securities	5,630	5,333
Trading Securities	490	592
Corporate Debt Securities
Available-for-sale Securities, Debt Securities	146,447	187,695
Residential Mortgage Backed Securities Member
Available-for-sale Securities, Debt Securities	6,677	5,913
US Treasury Securities
Available-for-sale Securities, Debt Securities	85,114	43,109
US Government Agencies Debt Securities
Available-for-sale Securities, Debt Securities	14	23
US Government-sponsored Enterprises Debt Securities
Available-for-sale Securities, Debt Securities	9,682	9,880
US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Debt Securities	179,643	186,811
Foreign Government Debt
Available-for-sale Securities, Debt Securities	4,150	4,954
Redeemable Preferred Stock
Available-for-sale Securities, Debt Securities	10,185	11,102
COMMON STOCK, AMOUNT
Available-for-sale Securities, Equity Securities	2,000	1,790
Nonredeemable Preferred Stock
Available-for-sale Securities, Equity Securities	3,630	3,543
Fair Value, Measurements, Recurring
Available-for-sale Securities, Debt Securities	441,912	449,487
Available-for-sale Securities, Equity Securities	5,630	5,333
Trading Securities	490	592
Assets, Fair Value Disclosure, Recurring	448,032	455,412
Fair Value, Measurements, Recurring | Corporate Debt Securities
Available-for-sale Securities, Debt Securities	146,447	187,695
Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities Member
Available-for-sale Securities, Debt Securities	6,677	5,913
Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities, Debt Securities	85,114	43,109
Fair Value, Measurements, Recurring | US Government Agencies Debt Securities
Available-for-sale Securities, Debt Securities	14	23
Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Available-for-sale Securities, Debt Securities	9,682	9,880
Fair Value, Measurements, Recurring | US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Debt Securities	179,643	186,811
Fair Value, Measurements, Recurring | Foreign Government Debt
Available-for-sale Securities, Debt Securities	4,150	4,954
Fair Value, Measurements, Recurring | Redeemable Preferred Stock
Available-for-sale Securities, Debt Securities	10,185	11,102
Fair Value, Measurements, Recurring | COMMON STOCK, AMOUNT
Available-for-sale Securities, Equity Securities	2,000	1,790
Fair Value, Measurements, Recurring | Nonredeemable Preferred Stock
Available-for-sale Securities, Equity Securities	3,630	3,543
Fair Value, Measurements, Recurring | Equity Securities
Trading Securities	490	592
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Available-for-sale Securities, Debt Securities	10,185	11,102
Available-for-sale Securities, Equity Securities	5,630	5,333
Trading Securities	490	592
Assets, Fair Value Disclosure, Recurring	16,305	17,027
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Corporate Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities Member
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US Government Agencies Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Foreign Government Debt
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Redeemable Preferred Stock
Available-for-sale Securities, Debt Securities	10,185	11,102
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | COMMON STOCK, AMOUNT
Available-for-sale Securities, Equity Securities	2,000	1,790
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Nonredeemable Preferred Stock
Available-for-sale Securities, Equity Securities	3,630	3,543
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Equity Securities
Trading Securities	490	592
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Available-for-sale Securities, Debt Securities	429,851	436,352
Available-for-sale Securities, Equity Securities	0	0
Trading Securities	0	0
Assets, Fair Value Disclosure, Recurring	429,851	436,352
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Corporate Debt Securities
Available-for-sale Securities, Debt Securities	146,447	187,695
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities Member
Available-for-sale Securities, Debt Securities	6,677	5,913
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities, Debt Securities	85,114	43,109
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US Government Agencies Debt Securities
Available-for-sale Securities, Debt Securities	14	23
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Available-for-sale Securities, Debt Securities	9,682	9,880
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Debt Securities	177,767	184,778
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Foreign Government Debt
Available-for-sale Securities, Debt Securities	4,150	4,954
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Redeemable Preferred Stock
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | COMMON STOCK, AMOUNT
Available-for-sale Securities, Equity Securities	0	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Nonredeemable Preferred Stock
Available-for-sale Securities, Equity Securities	0	0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Equity Securities
Trading Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Available-for-sale Securities, Debt Securities	1,876	2,033
Available-for-sale Securities, Equity Securities	0	0
Trading Securities	0	0
Assets, Fair Value Disclosure, Recurring	1,876	2,033
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Corporate Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Residential Mortgage Backed Securities Member
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | US Treasury Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | US Government Agencies Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | US States and Political Subdivisions Debt Securities
Available-for-sale Securities, Debt Securities	1,876	2,033
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Foreign Government Debt
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Redeemable Preferred Stock
Available-for-sale Securities, Debt Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | COMMON STOCK, AMOUNT
Available-for-sale Securities, Equity Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Nonredeemable Preferred Stock
Available-for-sale Securities, Equity Securities	0	0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Equity Securities
Trading Securities	$ 0	$ 0