Credit Risk (Details) (USD $)	Mar. 31, 2012 loan D	Dec. 31, 2011 loan
Credit Risk
Period of origination of loans within which they are sold to investors (in days)	30
Loan Servicing Portfolio Composition:
Total servicing portfolio	$ 184,881,000,000	$ 182,387,000,000
Weighted-average interest rate (as a percent)	4.50%	4.60%
Portfolio Delinquency
Number of Loans (as a percent)	3.13%	3.82%
Unpaid Balance (as a percent)	2.74%	3.29%
Foreclosure/real estate owned
Number of Loans (as a percent)	1.84%	1.83%
Unpaid Balance (as a percent)	1.86%	1.85%
Number of loans in foreclosure	16,004	15,689
Unpaid principal balance of loans in foreclosure	2,900,000,000	2,800,000,000
30 days
Portfolio Delinquency
Number of Loans (as a percent)	1.84%	2.24%
Unpaid Balance (as a percent)	1.54%	1.83%
60 days
Portfolio Delinquency
Number of Loans (as a percent)	0.44%	0.60%
Unpaid Balance (as a percent)	0.40%	0.51%
90 or more days
Portfolio Delinquency
Number of Loans (as a percent)	0.85%	0.98%
Unpaid Balance (as a percent)	0.80%	0.95%
Owned
Loan Servicing Portfolio Composition:
Total servicing portfolio	152,237,000,000	150,315,000,000
Subserviced
Loan Servicing Portfolio Composition:
Total servicing portfolio	32,644,000,000	32,072,000,000
Conventional loans
Loan Servicing Portfolio Composition:
Total servicing portfolio	147,523,000,000	145,885,000,000
Government loans
Loan Servicing Portfolio Composition:
Total servicing portfolio	30,877,000,000	29,903,000,000
Home equity lines of credit
Loan Servicing Portfolio Composition:
Total servicing portfolio	$ 6,481,000,000	$ 6,599,000,000