Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]: Debt Securities, Available-for-sale [Table Text Block] (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale, Amortized Cost	$ 454,567	$ 448,161
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	637	1,088
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	12,014	7,337
Debt Securities, Available-for-sale	443,190	441,912
Corporate Debt Securities
Debt Securities, Available-for-sale, Amortized Cost	160,659	148,996
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	106	298
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5,244	2,847
Debt Securities, Available-for-sale	155,521	146,447
Collateralized Mortgage Backed Securities
Debt Securities, Available-for-sale, Amortized Cost	6,691	6,857
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	327	180
Debt Securities, Available-for-sale	6,366	6,677
US Treasury Securities
Debt Securities, Available-for-sale, Amortized Cost	81,583	85,510
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	808	396
Debt Securities, Available-for-sale	80,775	85,114
US Government Agencies Debt Securities
Debt Securities, Available-for-sale, Amortized Cost	11	14
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	11	14
US Government-sponsored Enterprises Debt Securities
Debt Securities, Available-for-sale, Amortized Cost	9,812	9,887
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	219	205
Debt Securities, Available-for-sale	9,593	9,682
US States and Political Subdivisions Debt Securities
Debt Securities, Available-for-sale, Amortized Cost	181,626	182,664
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	349	598
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5,203	3,619
Debt Securities, Available-for-sale	176,772	179,643
Debt Security, Government, Non-US
Debt Securities, Available-for-sale, Amortized Cost	4,179	4,227
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	13
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	102	90
Debt Securities, Available-for-sale	4,077	4,150
Redeemable Preferred Stock
Debt Securities, Available-for-sale, Amortized Cost	10,006	10,006
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	180	179
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	111	0
Debt Securities, Available-for-sale	$ 10,075	$ 10,185

Amount, before tax, of unrealized gain 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).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

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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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Amortized cost of 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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 50
-Paragraph 2
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Amount of 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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
-Paragraph 1
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