Changes in Fair Value of Loans Held for Sale (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	$ (5,399)	[1]	$ 2,165	[1]	$ 1,001	[1]	$ (4,365)	[1]
Loans held for sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	(24,437)	[1]	28,727	[1]	(14,765)	[1]	33,674	[1]
Mortgage servicing rights
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	$ 19,038	[1]	$ (26,562)	[1]	$ 15,766	[1]	$ (38,039)	[1]

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