CREDIT QUALITY ASSESSMENT (Credit Risk Rating Indicators for Each Segment of Commercial Loan Portfolio) (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 10,343,043	$ 6,705,232
Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,222,810	801,019
Commercial Portfolio Segment [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		4,942,862
Commercial Portfolio Segment [Member] | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		801,019
Commercial Portfolio Segment [Member] | Pass
Financing Receivable Recorded Investment [Line Items]
Total loans		4,892,398
Commercial Portfolio Segment [Member] | Pass | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		783,909
Commercial Portfolio Segment [Member] | Special Mention
Financing Receivable Recorded Investment [Line Items]
Total loans		7,960
Commercial Portfolio Segment [Member] | Special Mention | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,487
Commercial Portfolio Segment [Member] | Substandard [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		42,504
Commercial Portfolio Segment [Member] | Substandard [Member] | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		14,623
Commercial Portfolio Segment [Member] | Doubtful
Financing Receivable Recorded Investment [Line Items]
Total loans		0
Commercial Portfolio Segment [Member] | Doubtful | Commercial [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		0
Commercial Real Estate Portfolio Segment | Commercial AD&C [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	997,423	684,010
Commercial Real Estate Portfolio Segment | Commercial Investor RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,581,778	2,169,156
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 1,601,803	1,288,677
Commercial Real Estate Portfolio Segment | Pass | Commercial AD&C [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		683,181
Commercial Real Estate Portfolio Segment | Pass | Commercial Investor RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,146,971
Commercial Real Estate Portfolio Segment | Pass | Commercial Owner Occupied RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		1,278,337
Commercial Real Estate Portfolio Segment | Special Mention | Commercial AD&C [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		0
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Investor RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		3,189
Commercial Real Estate Portfolio Segment | Special Mention | Commercial Owner Occupied RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		2,284
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial AD&C [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		829
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Investor RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		18,996
Commercial Real Estate Portfolio Segment | Substandard [Member] | Commercial Owner Occupied RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		8,056
Commercial Real Estate Portfolio Segment | Doubtful | Commercial AD&C [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		0
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Investor RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		0
Commercial Real Estate Portfolio Segment | Doubtful | Commercial Owner Occupied RE [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		$ 0