Loans to Banking Clients and Related Allowance for Loan Losses (Composition of Loans to Banking Clients by Loan Segment) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	$ 13,441	[1]	$ 12,467	[1]
Allowance for loan losses	(42)		(48)		(56)	(54)
Total loans to banking clients - net	13,399		12,419
Residential real estate mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	8,127		8,006
Allowance for loan losses	(29)		(34)		(36)	(40)
Home equity lines of credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	2,955		3,041
Allowance for loan losses	(13)		(14)		(20)	(14)
Personal loans secured by securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	2,320		1,384
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	$ 39		$ 36

[1] Loans are evaluated for impairment by loan segment.