Unresolved Claims by Claimant (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
GSE
Loss Contingencies Dollars
Balance, beginning of period	$ 4	$ 6
New demands	6	9
Loan paydowns/payoffs	(1)
Resolved claims	(7)	(11)
Balance, end of period	$ 2	$ 4
Loss Contingencies Units
Balance, beginning of period	16	37
New demands	71	118
Loan paydowns/payoffs	(4)	(4)
Resolved claims	(68)	(119)
Balance, end of period	15	32
Private Label
Loss Contingencies Dollars
Balance, beginning of period		$ 1
Resolved claims		$ (1)
Loss Contingencies Units
Balance, beginning of period	2	1
New demands	2	6
Resolved claims	(3)	(5)
Balance, end of period	1	2