Accounting for Certain Loans Acquired in a Transfer - Amounts of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	$ 1,100,794	$ 1,068,828
Carrying amount, net of allowance of $367 and $389	1,083,968	1,051,943
Loans Purchased With Evidence Of Credit Deterioration [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	43,528	60,294
Carrying amount, net of allowance of $367 and $389	43,161	59,905
Loans Purchased With Evidence Of Credit Deterioration [Member] | Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	22,223	37,048
Loans Purchased With Evidence Of Credit Deterioration [Member] | Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	11,033	11,761
Loans Purchased With Evidence Of Credit Deterioration [Member] | Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding balance	$ 10,272	$ 11,485