Changes in Residential and Securitized Mortgage Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of year					$ 227,297
Carrying value, end of period	220,371				227,297
Mortgage Servicing Rights Residential
Finite-Lived Intangible Assets [Line Items]
Carrying value, beginning of year	227,297		241,018
Additions	15,017		6,808
Due to changes in interest rates and valuation assumptions	(6,448)		43
Increase (decrease) in fair value, due to other changes	(15,495)	[1]	(9,865)	[1]
Amortization	0		0
Carrying value, end of period	$ 220,371		$ 238,004

[1] Net servicing cash flows, including loan payoffs, and the passage of time.