Quarterly report pursuant to sections 13 or 15(d)

Commitments and Contingencies - Additional Information (Detail)

Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	19 Months Ended			0 Months Ended	100 Months Ended	1 Months Ended		0 Months Ended	1 Months Ended
	Jun. 30, 2012 claim	Dec. 31, 2012	Dec. 31, 2011	Apr. 30, 2013 Subsequent event Massachusetts Securities Division [Member] plaintiffs	Apr. 30, 2013 Subsequent event Massachusetts Securities Division [Member]	Aug. 31, 2012 Compensatory damages	Feb. 28, 2012 Pending litigation	Aug. 10, 2012 Investacorp Inc	Jul. 31, 2012 Securities America Compensatory damages	Jun. 30, 2012 Securities America Compensatory damages
Loss Contingencies [Line Items]
Former clients of filed an arbitration claim	8
Number of remaining arbitration claims	3
Number of transactions				16
Damages sought by plaintiff					$ 915	$ 3,900	$ 941	$ 242	$ 3,800	$ 800
Accrued liabilities		$ 27	$ 27

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details