Loans, Leases and Allowance for Credit Losses - Troubled Debt Restructured Loans by Loan Class (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
Financing Receivable, Modifications [Line Items]
Number of Loans	4	6	11	39
Pre-Modification Outstanding Recorded Investment	$ 1,756	$ 3,557	$ 18,308	$ 23,520
Forgiven Principal Balance	0	267	825	1,297
Lost Interest Income	0	623	187	1,028
Post-Modification Outstanding Recorded Investment	1,756	2,667	17,296	21,195
Waived Fees and Other Expenses	0	9	52	81
Residential real estate
Financing Receivable, Modifications [Line Items]
Number of Loans	0	3	3	12
Pre-Modification Outstanding Recorded Investment	0	2,304	1,302	5,308
Forgiven Principal Balance	0	267	447	267
Lost Interest Income	0	613	70	887
Post-Modification Outstanding Recorded Investment	0	1,424	785	4,154
Waived Fees and Other Expenses	0	9	7	24
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans	0	0	0	2
Pre-Modification Outstanding Recorded Investment	0	0	0	74
Forgiven Principal Balance	0	0	0	0
Lost Interest Income	0	0	0	5
Post-Modification Outstanding Recorded Investment	0	0	0	69
Waived Fees and Other Expenses	0	0	0	3
Commercial real estate - owner occupied | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans	1	0	2	7
Pre-Modification Outstanding Recorded Investment	98	0	896	3,506
Forgiven Principal Balance	0	0	378	0
Lost Interest Income	0	0	117	54
Post-Modification Outstanding Recorded Investment	98	0	401	3,452
Waived Fees and Other Expenses	0	0	33	28
Non-owner occupied | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans	1	0	2	5
Pre-Modification Outstanding Recorded Investment	351	0	13,774	10,735
Forgiven Principal Balance	0	0	0	1,030
Lost Interest Income	0	0	0	63
Post-Modification Outstanding Recorded Investment	351	0	13,774	9,642
Waived Fees and Other Expenses	0	0	8	14
Multi-family | Commercial real estate
Financing Receivable, Modifications [Line Items]
Number of Loans	0	0	0	0
Pre-Modification Outstanding Recorded Investment	0	0	0	0
Forgiven Principal Balance	0	0	0	0
Lost Interest Income	0	0	0	0
Post-Modification Outstanding Recorded Investment	0	0	0	0
Waived Fees and Other Expenses	0	0	0	0
Commercial and industrial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans	2	3	4	11
Pre-Modification Outstanding Recorded Investment	1,307	1,253	2,336	3,611
Forgiven Principal Balance	0	0	0	0
Lost Interest Income	0	10	0	19
Post-Modification Outstanding Recorded Investment	1,307	1,243	2,336	3,592
Waived Fees and Other Expenses	0	0	4	11
Commercial leases | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Number of Loans	0	0	0	0
Pre-Modification Outstanding Recorded Investment	0	0	0	0
Forgiven Principal Balance	0	0	0	0
Lost Interest Income	0	0	0	0
Post-Modification Outstanding Recorded Investment	0	0	0	0
Waived Fees and Other Expenses	0	0	0	0
Construction | Construction and land development
Financing Receivable, Modifications [Line Items]
Number of Loans	0	0	0	0
Pre-Modification Outstanding Recorded Investment	0	0	0	0
Forgiven Principal Balance	0	0	0	0
Lost Interest Income	0	0	0	0
Post-Modification Outstanding Recorded Investment	0	0	0	0
Waived Fees and Other Expenses	0	0	0	0
Land | Construction and land development
Financing Receivable, Modifications [Line Items]
Number of Loans	0	0	0	2
Pre-Modification Outstanding Recorded Investment	0	0	0	286
Forgiven Principal Balance	0	0	0	0
Lost Interest Income	0	0	0	0
Post-Modification Outstanding Recorded Investment	0	0	0	286
Waived Fees and Other Expenses	$ 0	$ 0	$ 0	$ 1