Changes in MSRs Measured Using the Fair Value Method (Detail) (USD $) In Thousands	3 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Dec. 31, 2010
Servicing Assets at Fair Value [Line Items]
Fair value at beginning of period	$ 166,907		$ 169,747		$ 166,907
Purchases	860		4,015
Servicing from securitizations or asset transfers	11,292		7,809
Changes due to payments on loans	(8,397)	[1]	(7,932)	[1]
Changes in fair value due to changes in valuation model inputs or assumptions	(7,852)		(1,645)
Other disposals	(191)
Fair value at end of period	$ 162,619		$ 171,994		$ 166,907

[1] Represents the change in the market value of the MSR asset principally due to the impact of portfolio principal runoff during the period. It is computed as the sum of the monthly loan principal collections, curtailments, cancellations and repurchases multiplied by the MSR fair value percentage. A reduction in the loan portfolio balance causes a reduction in the contractual servicing fees for future periods.