Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	$ 2,784,266	$ 2,531,128
Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	356,651	346,708
Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	160,696	151,933
Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	552,178	456,888
Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	592,823	571,510
Pass | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	324,941	305,348
Special Mention | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	16,166	13,603
Substandard | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	15,274	26,091
Doubtful | Commercial
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	270	1,666
Commercial Portfolio Segment
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	1,662,348	1,527,039
Commercial Portfolio Segment | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	1,557,315	1,373,442
Commercial Portfolio Segment | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	34,812	54,621
Commercial Portfolio Segment | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	69,951	95,927
Commercial Portfolio Segment | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	270	3,049
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	160,696	151,933
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	552,178	456,888
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	592,823	571,510
Commercial Real Estate Portfolio Segment | Pass | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	154,869	141,802
Commercial Real Estate Portfolio Segment | Pass | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	523,901	405,448
Commercial Real Estate Portfolio Segment | Pass | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	553,604	520,844
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	0	1,793
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	2,944	21,963
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	15,702	17,262
Commercial Real Estate Portfolio Segment | Substandard | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	5,827	8,338
Commercial Real Estate Portfolio Segment | Substandard | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	25,333	28,885
Commercial Real Estate Portfolio Segment | Substandard | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	23,517	32,613
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	0	0
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Investor Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	0	592
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Owner Occupied Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans and leases	$ 0	$ 791