Contingencies and Other Risks (Narrative) (Details) (USD $) In Billions, unless otherwise specified	3 Months Ended
Jun. 30, 2012
Loss Contingency [Abstract]
Total Charge Recorded Related to ResCap Bankruptcy	$ 1.2

Total Charge Recorded Related to ResCap Bankruptcy

No definition available.

Name:	gjm_TotalChargeRecordedRelatedToRescapBankruptcy
Namespace Prefix:	gjm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration