Fair Value of Financial Instruments - Difference Between Fair Value and Principal Balance for Mortgage Loans Held for Sale Measured at Fair Value (Detail) (Mortgage Loans Held for Sale [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Mortgage Loans Held for Sale [Member]
Assets And Liabilities Carrying Value And Fair Value [Line Items]
Aggregate Fair Value of Mortgage Loans held for sale	$ 110,059	$ 67,278	$ 69,634
Aggregate Unpaid Principal Balance	105,882	65,522	67,406
Past due loans of 90 days or more
Nonaccrual loans