Bank Loans and Related Allowance for Loan Losses (Composition of Bank Loans by Loan Segment) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans	$ 13,641	[1]	$ 13,441	[1]
Allowance for loan losses	(38)		(42)		(48)	(48)
Total bank loans — net	13,603		13,399
Residential Real Estate Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans	8,172		8,127
Allowance for loan losses	(26)		(29)		(33)	(34)
Home Equity Loans and Lines of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans	2,878		2,955
Allowance for loan losses	(12)		(13)		(15)	(14)
Personal loans secured by securities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans	2,549		2,320
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Bank loans	$ 42		$ 39

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