Loans and Allowance for Loan Losses - Summary of Troubled Debt Restructurings Included in Purchased Non-Covered Loans, by Concessions Made Types (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	$ 20,900	$ 23,900
Purchased Non-Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	5,938
Purchased Non-Covered Loans [Member] | Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	24
Troubled debt restructuring loans	5,938
Purchased Non-Covered Loans [Member] | Accruing Loans [Member] | Forbearance of Interest [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Troubled debt restructuring loans	300
Purchased Non-Covered Loans [Member] | Accruing Loans [Member] | Forgiveness of Principal [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2
Troubled debt restructuring loans	425
Purchased Non-Covered Loans [Member] | Accruing Loans [Member] | Payment Modification Only [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2
Troubled debt restructuring loans	75
Purchased Non-Covered Loans [Member] | Accruing Loans [Member] | Rate Reduction Only [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	11
Troubled debt restructuring loans	2,170
Purchased Non-Covered Loans [Member] | Accruing Loans [Member] | Rate Reduction, Forbearance of Principal [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	8
Troubled debt restructuring loans	2,968
Purchased Non-Covered Loans [Member] | Non-Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	10
Troubled debt restructuring loans	1,212
Purchased Non-Covered Loans [Member] | Non-Accruing Loans [Member] | Rate Reduction Only [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	8
Troubled debt restructuring loans	707
Purchased Non-Covered Loans [Member] | Non-Accruing Loans [Member] | Rate Reduction, Forbearance of Principal [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2
Troubled debt restructuring loans	$ 505