Derivative Financial Instruments - Schedule of Net Gains (Losses) Related to Derivatives Not Designated as Hedging Instruments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on interest rate lock commitments	$ 141,746	$ 196,430
Interest Rate Lock Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on interest rate lock commitments	(17,217)	41,404
Forward Sales Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on interest rate lock commitments	183,625	179,688
Loan Purchase Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) on interest rate lock commitments	$ (24,662)	$ (24,662)