Acquisition of Businesses (Details) (USD $)	9 Months Ended			1 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Ally FInancial [Member]	Oct. 31, 2013 Subsequent Event [Member]	Sep. 30, 2013 Restatement Adjustment [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 2,600,000,000
Other Payments to Acquire Businesses				65,000,000
Debt of Subsidiary, Assumed and Repaid as part of Acquisition	1,400,000,000
Payments to Acquire Businesses, Gross	2,600,000,000			611,000,000
Business Combination, Contingent Consideration, Liability	900,000,000
Goodwill	1,156,000,000	1,108,000,000	48,000,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Consumer, Contractually Required Payments Receivable at Acquisition					1,200,000,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Consumer, Cash Flows Expected to be Collected at Acquisition					100,000,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Consumer, at Acquisition, at Fair Value					$ 1,000,000,000