CREDIT QUALITY ASSESSMENT (Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 4,314,248	$ 3,927,808
Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	497,948	467,286
Commercial Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,760,297	2,479,230
Commercial Portfolio Segment [Member] | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	497,948	467,286
Commercial Portfolio Segment [Member] | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	292,443	308,279
Commercial Portfolio Segment [Member] | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,112,710	928,113
Commercial Portfolio Segment [Member] | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	857,196	775,552
Commercial Portfolio Segment [Member] | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	2,723,813	2,426,773
Commercial Portfolio Segment [Member] | Pass | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	482,924	442,725
Commercial Portfolio Segment [Member] | Pass | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	292,307	308,142
Commercial Portfolio Segment [Member] | Pass | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,103,480	917,255
Commercial Portfolio Segment [Member] | Pass | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	845,102	758,651
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	11,465	21,660
Commercial Portfolio Segment [Member] | Special Mention | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	2,443	10,010
Commercial Portfolio Segment [Member] | Special Mention | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment [Member] | Special Mention | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	3,517	2,395
Commercial Portfolio Segment [Member] | Special Mention | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	5,505	9,255
Commercial Portfolio Segment [Member] | Substandard
Financing Receivable Recorded Investment [Line Items]
Total loans	25,019	30,797
Commercial Portfolio Segment [Member] | Substandard | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	12,581	14,551
Commercial Portfolio Segment [Member] | Substandard | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	136	137
Commercial Portfolio Segment [Member] | Substandard | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	5,713	8,463
Commercial Portfolio Segment [Member] | Substandard | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	6,589	7,646
Commercial Portfolio Segment [Member] | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment [Member] | Doubtful | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment [Member] | Doubtful | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment [Member] | Doubtful | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Portfolio Segment [Member] | Doubtful | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	292,443	308,279
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,112,710	928,113
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 857,196	$ 775,552