Derivatives (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
ASSETS
Net Amount, asset	$ 87	$ 178
LIABILITIES
Net Amount, liability	32	39
Not designated as hedging instruments
Derivatives
Cash collateral posted for derivative agreements that did not qualify for net presentation	1	1
ASSETS
Gross Assets, Subject to master netting agreements	22	15
Gross Assets, Not subject to master netting agreements	86	175
Gross Assets, Total	108	190
Offsetting Payables	(45)	(16)
Cash Collateral (Received) Paid	24	4
Net Amount, asset	87	178
LIABILITIES
Gross Liabilities, Subject to master netting agreements	59	14
Gross Liabilities, Not subject to master netting agreements	28	33
Gross Liabilities, Total	87	47
Offsetting Receivables	(45)	(16)
Cash Collateral Received	(10)	8
Net Amount, liability	32	39
Not designated as hedging instruments | Subject to master netting arrangements
ASSETS
Net Amount, asset	1	3
LIABILITIES
Net Amount, liability	4	6
Not designated as hedging instruments | Not subject to master netting arrangements
ASSETS
Net Amount, asset	86	175
LIABILITIES
Net Amount, liability	28	33
Not designated as hedging instruments | Forward delivery commitments
ASSETS
Gross Assets, Subject to master netting agreements	22	10
Gross Assets, Not subject to master netting agreements	3	5
Offsetting Payables	(45)	(12)
Cash Collateral (Received) Paid	24	5
Net Amount, asset	1	3
LIABILITIES
Gross Liabilities, Subject to master netting agreements	59	14
Gross Liabilities, Not subject to master netting agreements	10	5
Offsetting Receivables	(45)	(12)
Cash Collateral Received	(10)	(1)
Net Amount, liability	4	1
Not designated as hedging instruments | Forward delivery commitments | Subject to master netting arrangements
ASSETS
Net Amount, asset	1	3
LIABILITIES
Net Amount, liability	4	1
Not designated as hedging instruments | Forward delivery commitments | Not subject to master netting arrangements
ASSETS
Net Amount, asset	3	5
LIABILITIES
Net Amount, liability	10	5
Not designated as hedging instruments | MSR-related agreements
ASSETS
Gross Assets, Subject to master netting agreements		5
Offsetting Payables		(4)
Cash Collateral (Received) Paid		(1)
LIABILITIES
Offsetting Receivables		(4)
Cash Collateral Received		9
Net Amount, liability		5
Not designated as hedging instruments | Interest rate lock commitments
ASSETS
Gross Assets, Not subject to master netting agreements	62	140
Net Amount, asset	62	140
LIABILITIES
Gross Liabilities, Not subject to master netting agreements		1
Net Amount, liability		1
Not designated as hedging instruments | Option contracts
ASSETS
Gross Assets, Not subject to master netting agreements	1	2
Net Amount, asset	1	2
Not designated as hedging instruments | Interest rate contracts
ASSETS
Gross Assets, Not subject to master netting agreements	2	1
Net Amount, asset	2	1
Not designated as hedging instruments | Convertible note-related agreements
ASSETS
Gross Assets, Not subject to master netting agreements	18	27
Net Amount, asset	18	27
LIABILITIES
Gross Liabilities, Not subject to master netting agreements	18	27
Net Amount, liability	$ 18	$ 27