Regulatory Requirements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Regulatory Capital Requirements [Abstract]
Net assets held by regulated subsidiaries	$ 330.5
Aggregate regulatory net capital	$ 155.6

The amount by which the company's Total Capital exceeds the minimum required for capital adequacy purposes.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 505

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=7881181&loc=SL5958568-112826

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant