Receivable from and Payable to Brokers, Dealers and Clearing Organizations - Schedule of Receivable from and Payable to Brokers, Dealers and Clearing Organization (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Receivable from brokers, dealers and clearing organizations consist of:
Securities borrowed	$ 266,563	$ 242,172
Receivable from brokers	25,663us-gaap_DueFromCorrespondentBrokers	38,149us-gaap_DueFromCorrespondentBrokers
Securities failed to deliver	19,248us-gaap_SecuritiesFailedToDeliver	11,055us-gaap_SecuritiesFailedToDeliver
Clearing organizations	23,857	21,106
Other	2,772	1,993
Receivables from brokers, dealers and clearing organizations	338,103	314,475
Payable to brokers, dealers and clearing organizations consist of:
Securities loaned	165,005	137,892
Payable to brokers	7,347us-gaap_DueToCorrespondentBrokers	4,559us-gaap_DueToCorrespondentBrokers
Securities failed to receive	18,557us-gaap_SecuritiesFailedToReceive	23,573us-gaap_SecuritiesFailedToReceive
Other	159,321	91,137
Payable to brokers, dealers and clearing organizations	$ 350,230	$ 257,161

Receivable from and Payable to Brokers, Dealers and Clearing Organizations - Schedule of Receivable from and Payable to Brokers, Dealers and Clearing Organization (Details) (USD $)
In Thousands, unless otherwise specified

Mar. 31, 2015

Dec. 31, 2014

Receivable from brokers, dealers and clearing organizations consist of:

Securities borrowed

$ 266,563us-gaap_DepositsPaidForSecuritiesBorrowedAtCarryingValue

$ 242,172us-gaap_DepositsPaidForSecuritiesBorrowedAtCarryingValue

Receivable from brokers

25,663us-gaap_DueFromCorrespondentBrokers

38,149us-gaap_DueFromCorrespondentBrokers

Securities failed to deliver

19,248us-gaap_SecuritiesFailedToDeliver

11,055us-gaap_SecuritiesFailedToDeliver

Clearing organizations

23,857us-gaap_ReceivablesFromClearingOrganizations

21,106us-gaap_ReceivablesFromClearingOrganizations

Other

2,772us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations

1,993us-gaap_OtherReceivablesFromBrokerDealersAndClearingOrganizations

Receivables from brokers, dealers and clearing organizations

338,103us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations

314,475us-gaap_ReceivablesFromBrokersDealersAndClearingOrganizations

Payable to brokers, dealers and clearing organizations consist of:

Securities loaned

165,005us-gaap_DepositsReceivedForSecuritiesLoanedAtCarryingValue

137,892us-gaap_DepositsReceivedForSecuritiesLoanedAtCarryingValue

Payable to brokers

7,347us-gaap_DueToCorrespondentBrokers

4,559us-gaap_DueToCorrespondentBrokers

Securities failed to receive

18,557us-gaap_SecuritiesFailedToReceive

23,573us-gaap_SecuritiesFailedToReceive

Other

159,321us-gaap_OtherPayablesToBrokerDealersAndClearingOrganizations

91,137us-gaap_OtherPayablesToBrokerDealersAndClearingOrganizations

Payable to brokers, dealers and clearing organizations

$ 350,230us-gaap_PayablesToBrokerDealersAndClearingOrganizations

$ 257,161us-gaap_PayablesToBrokerDealersAndClearingOrganizations

- 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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 6

-Article 9

Reference 2: 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

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Balance Type:	debit
Period Type:	instant

- 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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 2: 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)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 20

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=51673353&loc=d3e41242-110953

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=35710130&loc=d3e41645-110958

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount payable to correspondent broker-dealer.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

Amount of other payables due to broker-dealers or clearing organizations.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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- Definition

Amount of other receivables due from broker-dealers or clearing organizations.

+ References

No definition available.

+ Details

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 20

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=35710130&loc=d3e41645-110958

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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

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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

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5066-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 20

-Section 25

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=35710059&loc=d3e41304-110954

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Balance Type:	debit
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- Definition

Amount receivable as the result of a fail-to-deliver. A fail-to-deliver is a securities sale to another broker-dealer that has not been delivered to buying broker-dealer by the close of business on the settlement date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Fail-to-Deliver

-URI http://asc.fasb.org/extlink&oid=34716026

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- Definition

Amount payable as the result of fail-to-receive. A fail-to-receive is a securities purchase from another broker-dealer not received from the selling broker-dealer by the close of business on the settlement date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Fail-to-Receive

-URI http://asc.fasb.org/extlink&oid=34716056

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