Unresolved Claims by Claimant (Detail) Pure in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)
GSE
Loss Contingencies Dollars
Balance, beginning of period	$ 6	$ 41
New demands	20	59
Loan paydowns/payoffs		(2)
Resolved claims	(20)	(90)
Balance, end of period	$ 6	$ 8
Loss Contingencies Units
Balance, beginning of period	37	264
New demands	240	464
Loan paydowns/payoffs	(12)	(24)
Resolved claims	(225)	(656)
Balance, end of period	40	48
Private Label
Loss Contingencies Dollars
Balance, beginning of period	$ 1	$ 5
Loan paydowns/payoffs		(1)
Resolved claims	$ (1)	(3)
Balance, end of period		$ 1
Loss Contingencies Units
Balance, beginning of period	1	33
New demands	11	10
Loan paydowns/payoffs		(2)
Resolved claims	(9)	(34)
Balance, end of period	3	7