CREDIT QUALITY ASSESSMENT (Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio) (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 6,551,243	$ 6,571,634
Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	772,158	796,264
Commercial Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,649,880	4,638,763
Commercial Portfolio Segment [Member] | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	772,158	796,264
Commercial Portfolio Segment [Member] | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans	4,596,372	4,576,321
Commercial Portfolio Segment [Member] | Pass | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	752,645	773,958
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans	12,138	8,827
Commercial Portfolio Segment [Member] | Special Mention | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	5,111	1,942
Commercial Portfolio Segment [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	41,370	53,615
Commercial Portfolio Segment [Member] | Substandard [Member] | Commercial
Financing Receivable Recorded Investment [Line Items]
Total loans	14,402	20,364
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 Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	658,709	681,201
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,994,027	1,958,395
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,224,986	1,202,903
Commercial Real Estate Portfolio Segment | Pass | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	656,719	677,574
Commercial Real Estate Portfolio Segment | Pass | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,972,903	1,934,886
Commercial Real Estate Portfolio Segment | Pass | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	1,214,105	1,189,903
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	0	321
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	3,910	3,826
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	3,117	2,738
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	1,990	3,306
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	17,214	19,683
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	7,764	10,262
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Acquisition, Development and Construction
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Investor Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	0	0
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Owner Occupied Real Estate
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 0	$ 0