Derivatives And Fair Value Measurements (Changes In Level 3 Fair Values) (Details) (USD $) In Thousands	3 Months Ended	6 Months Ended	9 Months Ended
Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2011
Derivatives And Fair Value Measurements [Abstract]
Beginning balance	$ 67,110	$ 19,115	$ 67,110
Included in OCI	18,258		18,258
Included in earnings	29,737		48,852
Ending balance	67,110	19,115	67,110
Total gains for the period included in earnings attributable to the change in unrealized gains related to assets held at September 30, 2011	$ 29,737		$ 48,852

This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income (or changes in net assets) in trading revenues. Such unrealized (holding) gains or losses relate to those assets still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

Name:	us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLossIncludedInTradingRevenue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration