Organization, Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($) $ in Billions	Mar. 31, 2016	Dec. 31, 2015
Margin Receivables [Abstract]
Margin receivables securities pledged as collateral	$ 8.7	$ 10.1
Margin receivable securities sold or repledged	$ 2.3	$ 2.5

Fair value as of the balance sheet date of customer securities accepted as collateral by the entity that it is permitted by contract or custom to sell or re-pledge to counterparties as collateral.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=55761124&loc=SL6224234-111729

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