Acquisitions (Amounts Allocated To Intangible Assets, The Amortization Period And Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended
	Feb. 28, 2013
Business Acquisition [Line Items]
Intangible assets	$ 283,432
Goodwill	1,701,616
Jefferies [Member]
Business Acquisition [Line Items]
Intangible assets	283,432
Goodwill	1,701,616
Total	1,985,048
Customer Relationships [Member] | Jefferies [Member]
Business Acquisition [Line Items]
Intangible assets	136,002
Tradenames And Related Trademarks [Member] | Jefferies [Member]
Business Acquisition [Line Items]
Intangible assets	131,299
Amortization Years	35 years
Exchange And Clearing Organization Membership Interests And Registrations [Member] | Jefferies [Member]
Business Acquisition [Line Items]
Intangible assets	$ 16,131
Minimum [Member] | Customer Relationships [Member] | Jefferies [Member]
Business Acquisition [Line Items]
Amortization Years	9 years
Maximum [Member] | Customer Relationships [Member] | Jefferies [Member]
Business Acquisition [Line Items]
Amortization Years	18 years