Goodwill and Intangible Assets Goodwill Details (Details) (Dahlman Rose & Company, LLC, USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Dahlman Rose & Company, LLC
Goodwill [Line Items]
Goodwill, Other Changes	$ 8.7

Amount of other (increase) decrease of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

Name:	us-gaap_GoodwillOtherChanges
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration