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	Sep. 30, 2014		Jun. 30, 2014	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	$ 13,120	[1]		$ 12,467	[1]
Allowance for loan losses	(40)		(41)	(48)		(52)	(57)	(56)
Total loans to banking clients - net	13,080			12,419
Residential real estate mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	8,075			8,006
Allowance for loan losses	(28)		(28)	(34)		(34)	(40)	(36)
Home equity lines of credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	2,982			3,041
Allowance for loan losses	(12)		(13)	(14)		(18)	(17)	(20)
Personal loans secured by securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	2,033			1,384
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to banking clients	$ 30			$ 36

[1] All loans are evaluated for impairment by loan segment.