Loans - Summary of Troubled Debt Restructurings Included in Covered Loans by Types of Concessions Made (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	$ 21,200	$ 20,900	$ 23,300
Covered Loans [Member] | Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	103	100	75
Troubled debt restructuring loans	22,775	22,243	19,762
Covered Loans [Member] | Accruing Loans [Member] | Forbearance of Interest [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts			3
Troubled debt restructuring loans			232
Covered Loans [Member] | Accruing Loans [Member] | Rate Reduction Only [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	90	89	61
Troubled debt restructuring loans	18,578	18,687	15,897
Covered Loans [Member] | Accruing Loans [Member] | Rate Reduction, Forbearance of Interest [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	3	4
Troubled debt restructuring loans	88	88	456
Covered Loans [Member] | Accruing Loans [Member] | Rate Reduction, Forbearance of Principal [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	9	7	6
Troubled debt restructuring loans	3,259	2,613	2,322
Covered Loans [Member] | Accruing Loans [Member] | Rate Reduction, Payment Modification [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1	1
Troubled debt restructuring loans	850	855	855
Covered Loans [Member] | Non-Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	27	24	20
Troubled debt restructuring loans	5,025	5,021	7,794
Covered Loans [Member] | Non-Accruing Loans [Member] | Forbearance of Interest [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	4	3	6
Troubled debt restructuring loans	127	98	1,077
Covered Loans [Member] | Non-Accruing Loans [Member] | Forgiveness of Principal [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts			1
Covered Loans [Member] | Non-Accruing Loans [Member] | Rate Reduction Only [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	10	9	8
Troubled debt restructuring loans	1,043	953	1,820
Covered Loans [Member] | Non-Accruing Loans [Member] | Rate Reduction, Forbearance of Interest [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	8	8	2
Troubled debt restructuring loans	471	478	1,362
Covered Loans [Member] | Non-Accruing Loans [Member] | Rate Reduction, Forbearance of Principal [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	4	3
Troubled debt restructuring loans	$ 3,384	$ 3,492	$ 3,535