Relationship with Bayview Lending Group LLC and Bayview Financial Holdings LP - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Minority interest in Bayview Lending Group LLC			20.00%
Carrying value of minority interest investment in Bayview Lending Group LLC	$ 98,000,000		$ 98,000,000
Outstanding principal balances of commercial mortgage servicing rights obtained from Bayview Financial	4,000,000,000		4,000,000,000		4,400,000,000
Amounts recorded as capitalized servicing assets for commercial mortgage loans	10,000,000		10,000,000		16,000,000
Servicing rights purchased from Bayview Financial related to residential mortgage loans	2,000,000		2,000,000		5,000,000
Outstanding principal balances of residential mortgage loans from Bayview Financial	2,800,000,000		2,800,000,000		3,100,000,000
Revenues earned for sub-servicing loans	9,000,000	10,000,000	27,000,000	31,000,000
Collateralized mortgage obligations in available-for-sale investment securities portfolio securitized by Bayview Financial	11,000,000		11,000,000		15,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	248,000,000		248,000,000		269,000,000
Bayview and Colonial [Member]
Schedule Of Equity Method Investments Joint Ventures [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	11,700,000,000		11,700,000,000		13,100,000,000
Revenues earned for sub-servicing loans	$ 2,000,000		$ 7,000,000