Receivables and Payables - Brokers, Dealers, and Clearing Organizations (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Receivables from brokers, dealers and clearing organizations
Broker-dealers	$ 245,645	$ 147,116
Clearing organizations	9,242	5,117
Securities borrowed	25,006	374
Allowance for doubtful accounts	(535)	(313)
Total	279,358	152,294
Payables to brokers, dealers and clearing organizations
Broker-dealers	110,103	56,894
Clearing organizations	9,770	8,096
Securities loaned	64,660	35,198
Total	$ 184,533	$ 100,188

Amounts payable to clearing organizations on open transactions and floor-brokerage payables.

No definition available.

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- Definition

Represents the allowance for doubtful accounts on receivables from brokers, dealers and clearing organizations.

+ References

No definition available.

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- Definition

This is the amount of cash advanced as security in return for borrowing securities from another party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 6
-Article 9

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- Definition

The amount of cash received as security in return for loaning securities to another party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

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- Definition

Amount receivable from correspondent broker-dealer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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- Definition

Amount payable to correspondent broker-dealer.

+ References

No definition available.

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- Definition

Amount payable to broker-dealers and clearing organizations, including, but not limited to, securities failed-to-receive, certain deposits received for securities loaned, open transactions, and floor-brokerage payables.

+ References

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- Definition

Amount receivable from broker-dealers and clearing organizations, including, but not limited to, securities failed-to-deliver, certain deposits for securities borrowed, open transactions, good faith and margin deposits, commissions and floor brokerage receivables.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 940
-SubTopic 20
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-Paragraph 3
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No definition available.

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- Definition

Amount of right to receive cash and securities on deposit with clearing organizations. Clearing organizations perform post trade processing and trade comparisons among numerous broker-dealers and act as settlement agents between buying and selling broker-dealers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
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