Unresolved Claims by Claimant (Detail) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2008
Loss Contingencies Units
Resolved claims			(2)
GSE
Loss Contingencies Dollars
Balance, beginning of period	$ 6	$ 41
New demands	26	84
Loan paydowns/payoffs	(2)	(4)
Resolved claims	(26)	(106)
Balance, end of period	$ 4	$ 15
Loss Contingencies Units
Balance, beginning of period	37	264
New demands	350	643
Loan paydowns/payoffs	(26)	(33)
Resolved claims	(337)	(780)
Balance, end of period	24	94
Private Label
Loss Contingencies Dollars
Balance, beginning of period	$ 1	$ 5
New demands	42
Loan paydowns/payoffs		(1)
Resolved claims	$ (43)	$ (4)
Loss Contingencies Units
Balance, beginning of period	1	33
New demands	257	11
Loan paydowns/payoffs		(2)
Resolved claims	(258)	(42)