Changes in Fair Value of Loans Held for Sale (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	$ (17,574)	[1]	$ (8,155)	[1]
Loans held for sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	4,369	[1]	1,667	[1]
Mortgage servicing rights
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	$ (21,943)	[1]	$ (9,822)	[1]

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