Loans Held for Sale, Loan Servicing and Mortgage Origination (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Servicing Asset	$ 1,900,000,000		$ 1,900,000,000
Servicing Fees, Net	1,200,000	956,000
Loans Held-for-sale, Mortgages	$ 33,800,000		$ 55,200,000