Loan Servicing (Commercial Mortgage Banking Activities) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2012		Dec. 31, 2011
Loan Servicing [Abstract]
Unpaid principal balances of commercial mortgage loans serviced for others	$ 25,741		$ 25,367
Commercial real estate mortgages serviced for others covered by recourse provisions	4,762		4,520
Maximum recourse exposure from commercial real estate mortgages sold with recourse liability	1,297		1,226
Recorded reserves related to recourse exposure	14		15
Originated commercial real estate mortgages during the period	$ 2,275	[1]	$ 4,803	[1]

[1] Originated commercial real estate mortgages for June 30, 2012 reflect six months.