Other Noninterest Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Component of Other Expense, Nonoperating [Line Items]
Valuation losses on affordable housing investments	$ 96	$ 10	$ 15
Other Staff Expense	94	95	55
Postage Expense	76	81	83
Communication	63	63	64
Supplies Expense	34	45	47
Other Expenses	326	317	344
Other Noninterest Expense	$ 689	$ 611	$ 608