Loans and Leases (Impaired Loans) (Details) (Commercial Real Estate, USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	$ 130			$ 130			$ 197
Unpaid principal balance with no related allowance recorded	198			198			322
Related allowance	0	[1]		0	[1]		0	[1]
Additional allowance for loan losses	22			22			22
Average recorded investment	130		204	160		216
Interest revenue recognized	2		4	17		12
CRE - property development
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	130			130			197
Unpaid principal balance with no related allowance recorded	143			143			224
Related allowance	0	[1]		0	[1]		0	[1]
Average recorded investment	130		199	160		199
Interest revenue with related allowance recognized	2		4	17		12
CRE - property development - acquired credit impaired
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	0			0			0
Unpaid principal balance with no related allowance recorded	34			34			34
Related allowance	0	[1]		0	[1]		0	[1]
CRE - other - acquired credit impaired
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	0			0			0
Unpaid principal balance with no related allowance recorded	21			21			64
Related allowance	0	[1]		0	[1]		0	[1]
Average recorded investment	0		5	0		17
Interest revenue with related allowance recognized	0		0	0		0
Recorded investment with related allowance	0		0	0		0
Interest revenue with no related allowance recognized	$ 0		$ 0	$ 0		$ 0

[1] As of both September 30, 2013 and December 31, 2012, we maintained an allowance for loan losses of $22 million associated with loans and leases that were not impaired.