Basis of Presentation and Summary of Significant Accounting Policies Significant Accounting Policies Text (Details) - USD ($)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Accounting Policies [Abstract]
Gain on sale of offices	$ 2,862,000	$ 0	$ 0
Cash Reserve Deposit Required and Made	5,000,000	4,600,000
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	$ 0	$ 0	$ 0

Significant Accounting Policies [Abstract]

No definition available.

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- Definition

Cash deposited in a special reserve account for the exclusive benefit of customers pursuant to SEC Regulations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 305
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6478312&loc=d3e61473-112792

+ Details

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- Definition

Amount of gain (loss) on sale or disposal of other assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 8B
-URI http://asc.fasb.org/extlink&oid=73527792&loc=SL6284393-111563

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