Fair Value - Components of Net Gains on Sales of Loans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Components of Net Gains on Sales of Loans (Detail) [Line Items]
Realized gains on sales of loans	$ 367,314	$ 218,504	$ 537
Change in unrealized gains (losses) on loans held for sale	1,412	24,771	266
Capitalized servicing rights	214,285	187,749	0
Provision for repurchases	(7,741)us-gaap_ProvisionForOtherLosses	(9,067)us-gaap_ProvisionForOtherLosses	(18)us-gaap_ProvisionForOtherLosses
Interest income	40,051	32,625	16
Other	0	35	0
Net gains on sales of loans	462,172us-gaap_GainLossOnSaleOfMortgageLoans	598,974us-gaap_GainLossOnSaleOfMortgageLoans	648us-gaap_GainLossOnSaleOfMortgageLoans
Interest Rate Lock Commitments [Member]
Components of Net Gains on Sales of Loans (Detail) [Line Items]
Net fair value gains (losses) on derivatives	21,061	38,126	949
Forward Sales Commitments [Member]
Components of Net Gains on Sales of Loans (Detail) [Line Items]
Net fair value gains (losses) on derivatives	(156,201)	111,830	(1,102)
MBS Purchase Commitments [Member]
Components of Net Gains on Sales of Loans (Detail) [Line Items]
Net fair value gains (losses) on derivatives	$ (18,009)	$ (5,599)	$ 0

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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Interest and fee income from mortgage loans considered to be held-for-sale.

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Amount of expense related to other loss.

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Reflects, by transferred financial asset type, the amount of sales proceeds in excess of or deficient from the sum of the carrying amounts of transferred financial assets plus transaction costs, including those transactions in which the seller/transferor has continuing involvement with the financial assets that have been transferred.

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Change in Unrealized Gain Loss on Loans Held for Sale

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Gain associated with capitalized servicing rights.

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Other changes in mortgage loans held for sale.

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