Federal Funds Sold and Securities Borrowed or Purchased Under Agreements to Resell Netting of financial instruments - repurchase agreements (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Assets Sold under Agreements to Repurchase [Line Items]
Carrying Value of Securities Purchased under Agreements to Resell and Deposits Paid for Securities Borrowed	$ 1,042		$ 1,072
Securities Borrowed or Purchased Under Agreements to Resell, Amount Offset Against Collateral	0		0
Federal Funds Sold and Securities Borrowed or Purchased under Agreements to Resell, Fair Value Disclosure	1,042	[1]	1,072	[1],[2]
Held Financial Instruments, Not Separately Reported, Securities for Reverse Repurchase Agreements	1,033		1,069
Securities Borrowed or Purchased Under Agreements to Resell, Amount Not Offset Against Collateral	9		3
Carrying Value of Securities Sold under Repurchase Agreements and Deposits Received for Securities Loaned	1,869		1,574
Securities Sold Under Agreements to Repurchase, Amount Offset Against Collateral	0		0
Securities Sold under Agreements to Repurchase	1,869	[1]	1,574	[1]
Pledged Financial Instruments, Not Separately Reported, Securities for Repurchase Agreements	1,869		1,574
Securities Sold Under Agreements to Repurchase, Amount Not Offset Against Collateral	$ 0		$ 0

[1] 1 None of the Company's repurchase and reverse repurchase transactions met the right of setoff criteria at June 30, 2013 and December 31, 2012.

[2] 2 Excludes $69 million and $29 million of Fed funds sold which are not subject to a master netting agreement at June 30, 2013 and December 31, 2012, respectively.