Unresolved Claims by Claimant (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2008
Loss Contingencies Units
Resolved claims			2
GSE
Loss Contingencies Dollars
Balance, beginning of period	$ 6	$ 41
New demands	33	95
Loan paydowns/payoffs	(2)	(5)
Resolved claims	(33)	(125)
Balance, end of period	$ 4	$ 6
Loss Contingencies Units
Balance, beginning of period	37	264
New demands	436	744
Loan paydowns/payoffs	(29)	(44)
Resolved claims	(428)	(927)
Balance, end of period	16	37
Private Label
Loss Contingencies Dollars
Balance, beginning of period	$ 1	$ 5
New demands	42	2
Loan paydowns/payoffs		(1)
Resolved claims	$ (43)	(5)
Balance, end of period		$ 1
Loss Contingencies Units
Balance, beginning of period	1	33
New demands	261	14
Loan paydowns/payoffs		(2)
Resolved claims	(260)	(44)
Balance, end of period	2	1