Acquisition of Businesses Purchase Price Allocation (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Restricted Cash and Cash Equivalents	$ 1,397,000	$ 744,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	50,000,000
Business Acquisition, Cost of Acquired Entity, Purchase Price	2,600,000,000
Ally FInancial [Member]
Business Acquisition, Purchase Price Allocation, Current Assets, Cash and Cash Equivalents	440,000,000
Restricted Cash and Cash Equivalents	525,000,000
Business Combination, Acquired Receivables, Fair Value	10,981,000,000
Business Acquisition, Purchase Price Allocation, Other Noncurrent Assets	254,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Financial Liabilities	8,910,000,000
Business Acquisition, Purchase Price Allocation, Other Noncurrent Liabilities	722,000,000
Identifiable net assets acquired	2,568,000,000
Business Acquisition, Purchase Price Allocation, Goodwill Amount	50,000,000
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 2,618,000,000