CREDIT QUALITY ASSESSMENT (Additional Information) (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable Troubled Debt Restructurings Specific Allowance	$ 406	$ 563
Other real estate owned	1,486	1,584
Non-accrual loans	34,312	33,583
Loans and Leases Receivable, Net of Deferred Income, Total	6,551,243	6,571,634
Homogeneous Loan Pools
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income, Total	1,901,363	1,932,871
Performing Financing Receivable [Member] | Homogeneous Loan Pools
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income, Total	1,885,205	1,917,387
WashingtonFirst Bankshares Inc [Member] | Performing Financing Receivable [Member] | Homogeneous Loan Pools
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	1,200	1,300
WashingtonFirst Bankshares Inc [Member] | Special Mention [Member] | Performing Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income, Total	2,000	4,200
WashingtonFirst Bankshares Inc [Member] | Substandard | Credit impaired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income, Total	12,100	24,300
WashingtonFirst Bankshares Inc [Member] | Substandard | Performing Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Net of Deferred Income, Total	8,100	7,200
Restructured Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable Troubled Debt Restructurings Specific Allowance	400	600
Other real estate owned	1,500	1,600
Additional Financing Receivable Troubled Debt Restructurings Restructured	1,800	1,600
Restructured Loans | WashingtonFirst Bankshares Inc [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual loans	$ 4,300	$ 4,800