Loans Held for Sale, Loan Servicing and Mortgage Origination (Detail) - Schedule of Mortgage Loan Securitizations and Whole Loan Sales (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Loan securitizations and loan sales	$ 177,850	$ 158,208
Loan Securization With Fannie Mae [Member]
Loan securitizations and loan sales	71,131	127,401
Loan Sales To Fannie Mae [Member]
Loan securitizations and loan sales	102,540	23,031
Loan Sales To FHLB [Member]
Loan securitizations and loan sales	3,521	2,678
Loan Sales To Other Investors [Member]
Loan securitizations and loan sales	$ 658	$ 5,098