Receivables from Brokerage Clients (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Receivables from Brokerage Clients [Abstract]
Margin loans to brokerage clients	$ 15.8	$ 14.3
Average yield earned on margin loans	3.30%	3.50%