Changes in Fair Value of Loans Held for Sale (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	[1]	$ (21,201)	$ (36,861)	$ 5,439
Loans held for sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	[1]	11,697	11,681	(10,260)
Mortgage servicing rights
Fair Value, Option, Quantitative Disclosures [Line Items]
Mortgage Banking Income	[1]	$ (32,898)	$ (48,542)	$ 15,699

[1] Does not include the effect of hedging activities, which is included in "Other non-interest income."