Credit Quality Assessment (Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 3,495,370	$ 3,127,392
Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	465,765	390,781
Pass | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	447,439	366,367
Special Mention | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	797	8,835
Substandard | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	17,529	15,579
Doubtful | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	0
Commercial Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	2,118,856	1,847,159
Commercial Portfolio Segment [Member] | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	2,069,129	1,771,095
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	5,662	21,133
Commercial Portfolio Segment [Member] | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	44,065	54,931
Commercial Portfolio Segment [Member] | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	0
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	255,980	205,124
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	719,084	640,193
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	678,027	611,061
Commercial Real Estate Portfolio Segment | Pass | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	255,786	201,642
Commercial Real Estate Portfolio Segment | Pass | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	706,623	621,511
Commercial Real Estate Portfolio Segment | Pass | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	659,281	581,575
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	0	698
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	1,509	3,931
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	3,356	7,669
Commercial Real Estate Portfolio Segment | Substandard | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	194	2,784
Commercial Real Estate Portfolio Segment | Substandard | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	10,952	14,751
Commercial Real Estate Portfolio Segment | Substandard | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	15,390	21,817
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	0
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans and leases	$ 0	$ 0