Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Components of Mortgage loans held for sale
Mortgage loans held for sale	$ 1,155	$ 2,174
Derivative Instruments
Average pull through percentage used in measuring fair value of interest rate lock commitments	74.00%	74.00%
First mortgages
Components of Mortgage loans held for sale
Mortgage loans held for sale	1,096	2,109
First mortgages, Conforming
Components of Mortgage loans held for sale
Mortgage loans held for sale	1,022	1,966
First mortgages, Non-conforming
Components of Mortgage loans held for sale
Mortgage loans held for sale	74	143
Second lien
Components of Mortgage loans held for sale
Mortgage loans held for sale	5	8
Scratch and Dent
Components of Mortgage loans held for sale
Mortgage loans held for sale	54	56
Other
Components of Mortgage loans held for sale
Mortgage loans held for sale		$ 1