Receivables from and Payables to Brokers, Dealers and Clearing Organizations - Amounts Receivable from Brokers, Dealers and Clearing Organizations (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Disclosure Amounts Receivable From Brokers Dealers And Clearing Organizations [Abstract]
Receivable arising from unsettled securities transactions	$ 59,657	$ 66,426
Deposits paid for securities borrowed	36,278	32,163
Receivable from clearing organizations	966	17,655
Deposits with clearing organizations	20,995	24,717
Securities failed to deliver	593	5,440
Other	8,624	1,716
Brokers, dealers and clearing organizations	$ 127,113	$ 148,117