Credit Risk (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Changes in repurchase and foreclosure-related reserves
Balance, beginning of period	$ 93	$ 142
Realized losses	(19)	(65)	[1]
Increase in reserves due to:
Changes in assumptions	6	6	[1]
New loan sales	9	10
Balance, end of period	89	93
Loss contingencies
Provision for estimated losses related to sale of existing MSRs		8
Liabilities for probable losses related to repurchase and indemnification obligations	62	63
Estimated amount of reasonably possible losses in excess of the recorded liability	150
Loans with full risk of loss or with respect to which the company has identified a breach of representation and warranty provisions	$ 174
Percentage of loans with full risk of loss or with respect to which the company has identified a breach of representation and warranty provisions and are at least 90 days delinquent	9.00%
Recourse obligations
Loss contingencies
Estimated amount of reasonably possible losses in excess of the recorded liability	$ 30
Fannie Mae
Loss contingencies
Realized losses for repurchase and foreclosure-related reserves that were related to the resolution agreement		$ 12

[1] Realized losses includes $12 million that was paid to Fannie Mae related to a resolution agreement and Changes in assumptions includes an $8 million provision for estimated losses related to the sale of MSRs for certain highly delinquent government insured loans.