Changes in Residential and Securitized Mortgage Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified			3 Months Ended				6 Months Ended				3 Months Ended		6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Mortgage Servicing Rights Residential		Jun. 30, 2012 Mortgage Servicing Rights Residential		Jun. 30, 2013 Mortgage Servicing Rights Residential		Jun. 30, 2012 Mortgage Servicing Rights Residential		Jun. 30, 2013 Securitized Mortgage Servicing Rights	Jun. 30, 2012 Securitized Mortgage Servicing Rights	Jun. 30, 2013 Securitized Mortgage Servicing Rights	Jun. 30, 2012 Securitized Mortgage Servicing Rights
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of year	$ 215,055	$ 144,713	$ 172,849		$ 139,792		$ 144,520		$ 116,416		$ 129	$ 483	$ 193	$ 596
Additions			23,072		22,946		54,673		57,799
Due to changes in valuation assumptions			34,754		(11,790)		47,848		(7,534)
Increase (decrease) in fair value, due to other changes			(15,716)	[1]	(14,772)	[1]	(32,082)	[2]	(30,505)	[2]
Amortization											(33)	(97)	(97)	(210)
Carrying value, end of period	$ 215,055	$ 144,713	$ 214,959		$ 136,176		$ 214,959		$ 136,176		$ 96	$ 386	$ 96	$ 386

[1] Includes net servicing cash flows and the passage of time.

[2] Includes net servicing cash flows, including loan payoffs, and the passage of time.