Acquisition of KBW, Inc. (Fair Value Of Assets Acquired And Liabilities Assumed) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013
Acquisition of KBW, Inc.
Cash and cash equivalents	$ 98,756
Receivables from clearing organizations	74,264
Financial instruments owned, at fair value	120,540
Fixed assets, net	10,629
Deferred tax assets, net	78,724
Other assets	31,626
Total assets acquired	414,539
Financial instruments sold, but not yet purchased, at fair value	53,379
Accrued compensation	21,418
Accounts payable and accrued expenses	50,104
Total liabilities assumed	124,901
Net assets acquired	$ 289,638