Non-Covered Loan and Lease Finance Receivables and Allowance for Loan Losses - Summary of Loans Modified as Troubled Debt Restructurings (Detail) (USD $)
In Thousands, unless otherwise specified

Non-Covered Loan and Lease Finance Receivables and Allowance for Loan Losses - Summary of Loans Modified as Troubled Debt Restructurings (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract
Non-Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans		3	6	12
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment		$ 3,676	$ 4,140	$ 19,281
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment		3,676	4,140	19,281
Troubled debt restructurings, Outstanding Recorded Investment		3,590	3,993	16,434
Troubled debt restructurings, Financial Effect Resulting From Modifications				122
Commercial and industrial [Member] \| Interest rate reduction [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans			2
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment			368
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment			368
Troubled debt restructurings, Outstanding Recorded Investment			337
Troubled debt restructurings, Financial Effect Resulting From Modifications
Commercial and industrial [Member] \| Change in amortization period or maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans		1		4
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment		34		265
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment		34		265
Troubled debt restructurings, Outstanding Recorded Investment		34		223
Troubled debt restructurings, Financial Effect Resulting From Modifications				122
Commercial real estate Owner occupied [Member] \| Interest rate reduction [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans			1
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment			199
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment			199
Troubled debt restructurings, Outstanding Recorded Investment			187
Troubled debt restructurings, Financial Effect Resulting From Modifications
Commercial real estate Owner occupied [Member] \| Change in amortization period or maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans				1
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment				168
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment				168
Troubled debt restructurings, Outstanding Recorded Investment				143
Troubled debt restructurings, Financial Effect Resulting From Modifications
Commercial real estate Owner occupied [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment
Troubled debt restructurings, Outstanding Recorded Investment
Troubled debt restructurings, Financial Effect Resulting From Modifications
Commercial real estate Non-owner occupied [Member] \| Interest rate reduction [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans			3
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment			3,573
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment			3,573
Troubled debt restructurings, Outstanding Recorded Investment			3,469
Troubled debt restructurings, Financial Effect Resulting From Modifications
Commercial real estate Non-owner occupied [Member] \| Change in amortization period or maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment
Troubled debt restructurings, Outstanding Recorded Investment
Troubled debt restructurings, Financial Effect Resulting From Modifications
Commercial real estate Non-owner occupied [Member] \| Other [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment
Troubled debt restructurings, Outstanding Recorded Investment
Troubled debt restructurings, Financial Effect Resulting From Modifications
Dairy & livestock and agribusiness [Member] \| Interest rate reduction [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment
Troubled debt restructurings, Outstanding Recorded Investment
Troubled debt restructurings, Financial Effect Resulting From Modifications
Dairy & livestock and agribusiness [Member] \| Change in amortization period or maturity [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructurings, Number of Loans		2		7
Troubled debt restructurings, Pre-Modification Outstanding Recorded Investment		3,642		18,848
Troubled debt restructurings, Post-Modification Outstanding Recorded Investment		3,642		18,848
Troubled debt restructurings, Outstanding Recorded Investment		3,556		16,068
Troubled debt restructurings, Financial Effect Resulting From Modifications