Loans and Allowance for Loan Losses - Summary of Non-Performing Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructurings	$ 42,062	$ 41,623
Non-Performing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	60,039	58,755
Troubled debt restructurings	19,384	18,698
Total non-performing loans	79,423	77,453
Other real estate owned (OREO)	43,216	40,681
Total non-performing loans and OREO	122,639	118,134
Non-performing investments		797
Total non-performing assets	$ 122,639	$ 118,931
Non-performing loans as a percent of total loans	0.80%	0.81%
Non-performing loans + OREO as a percent of total loans + OREO	1.23%	1.24%
Non-performing assets as a percent of total assets	0.85%	0.88%