CREDIT QUALITY ASSESSMENT (Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 6,571,634	$ 4,314,248
Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	796,264	497,948
Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	53,615	25,019
Commercial Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,638,763	2,760,297
Commercial Portfolio Segment [Member] | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	796,264	497,948
Commercial Portfolio Segment [Member] | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	681,201	292,443
Commercial Portfolio Segment [Member] | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,958,395	1,112,710
Commercial Portfolio Segment [Member] | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,202,903	857,196
Commercial Portfolio Segment [Member] | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	4,576,321	2,723,813
Commercial Portfolio Segment [Member] | Pass | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	773,958	482,924
Commercial Portfolio Segment [Member] | Pass | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	677,574	292,307
Commercial Portfolio Segment [Member] | Pass | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,934,886	1,103,480
Commercial Portfolio Segment [Member] | Pass | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,189,903	845,102
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	8,827	11,465
Commercial Portfolio Segment [Member] | Special Mention | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	1,942	2,443
Commercial Portfolio Segment [Member] | Special Mention | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	321	0
Commercial Portfolio Segment [Member] | Special Mention | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	3,826	3,517
Commercial Portfolio Segment [Member] | Special Mention | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	2,738	5,505
Commercial Portfolio Segment [Member] | Substandard [Member] | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	20,364	12,581
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	681,201	292,443
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,958,395	1,112,710
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,202,903	857,196
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	3,306	136
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	19,683	5,713
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 10,262	$ 6,589