Net Capital Requirements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Net Capital Requirements (Textual) [Abstract]
Percentage of aggregate debit items arising from customer transactions to maintain minimum net capital requirements	2.00%
Minimum net capital requirements	$ 250
Partners net capital	711,894
Percentage of aggregate debit items of partners net capital	34.00%
Partners net capital in excess of the minimum requirement	670,072
Net capital after anticipated withdrawals, as a percentage of aggregate debit items	18.50%
Canadian broker-dealer's regulatory risk adjusted capital	38,488
Capital in excess required to be held by the Investment Industry Regulatory Organization of Canada	$ 27,567