Changes in MSRs measured using the fair value method (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011
Servicing Assets at Fair Value [Line Items]
Fair value at beginning of period	$ 151,323		$ 166,907
Purchases	1,018		860
Servicing Asset At Fair Value Securitizations Or Asset Transfers	8,206		11,292
Servicing Asset At Fair Value Payments On Loans	(8,950)	[1]	(6,577)	[1]
Reduction Due To Loan Repurchases	(1,360)		(1,820)
Servicing Asset At Fair Value Changes In Fair Value Resulting From Changes In Valuation Inputs Or Changes In Assumptions	5,519		(7,852)
Servicing Asset At Fair Value Other Changes That Affect Balance	(45)		(191)
Fair value at end of period	$ 155,711		$ 162,619

[1] Represents changes due to collection / realization of expected cash flows over time.