Changes in Fair Value of Loans Held for Sale (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	$ 1,313	[1]	$ 4,801	[1]	$ 2,314	[1]	$ 436	[1]
Loans held for sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	6,892	[1]	46,915	[1]	(7,873)	[1]	80,589	[1]
Mortgage servicing rights
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	$ (5,579)	[1]	$ (42,114)	[1]	$ 10,187	[1]	$ (80,153)	[1]

[1] Does not include the effect of hedging activities.