Available for Sale Securities (Amortized Cost, Gross Unrealized Gains and Losses and Estimated Fair Value of Available for Sale Investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Investments [Line Items]
Amortized Cost	$ 294,599	$ 274,457
Gross Unrealized Gains	41,613	26,712
Gross Unrealized Losses	157	120
Estimated Fair Value	336,055	301,049
U.S. Government Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	169,365	174,938
Gross Unrealized Gains	5	8
Gross Unrealized Losses	54	13
Estimated Fair Value	169,316	174,933
Residential Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	32,714	19,129
Gross Unrealized Gains	191	108
Gross Unrealized Losses	80	104
Estimated Fair Value	32,825	19,133
Commercial Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	8,895	8,275
Gross Unrealized Gains	62	64
Gross Unrealized Losses	10	2
Estimated Fair Value	8,947	8,337
Other Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	30,608	18,918
Gross Unrealized Gains	112	124
Gross Unrealized Losses	13	0
Estimated Fair Value	30,707	19,042
All Other Corporates [Member]
Schedule of Investments [Line Items]
Amortized Cost		180
Gross Unrealized Gains		0
Gross Unrealized Losses		1
Estimated Fair Value		179
Debt Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	241,582	221,440
Gross Unrealized Gains	370	304
Gross Unrealized Losses	157	120
Estimated Fair Value	241,795	221,624
Common Stocks: Banks, Trusts And Insurance Companies [Member]
Schedule of Investments [Line Items]
Amortized Cost	35,071	35,071
Gross Unrealized Gains	23,699	15,115
Gross Unrealized Losses	0	0
Estimated Fair Value	58,770	50,186
Common Stocks: Industrial, Miscellaneous And All Other [Member]
Schedule of Investments [Line Items]
Amortized Cost	17,946	17,946
Gross Unrealized Gains	17,544	11,293
Gross Unrealized Losses	0	0
Estimated Fair Value	35,490	29,239
Corporate Equity Securities [Member]
Schedule of Investments [Line Items]
Amortized Cost	53,017	53,017
Gross Unrealized Gains	41,243	26,408
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 94,260	$ 79,425

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
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