Amount of advances or credit lines used from the Federal Home Loan Bank (FHLB).

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Short-term Advances, Overnight Maturities

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Short-term Advances, Percentage Bearing Fixed Interest Rate

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Face (par) amount of debt instrument at time of issuance.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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States the interest rate applicable to Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

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Amount of maximum advances or credit lines available from the Federal Home Loan Bank (FHLB).

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The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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Amount of cash outflow for the payment of debt classified as other, maturing after one year or the operating cycle, if longer.

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The cash outflow from the repayment of long-term borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in case of liquidation of the entity's assets or underlying collateral.

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BORROWINGS - Additional Information (Detail) - USD ($)	3 Months Ended
BORROWINGS - Additional Information (Detail) - USD ($)	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Overnight maturities	41.60%		57.20%
Short-term advances, percentage bearing fixed interest rate	58.40%		42.80%
Repayments of subordinated debt	$ 9,500,000
Repayments of other long-term debt	15,500,000
Redeemed amount	179,000,000	$ 18,000,000
FHLB [Member]
Debt Instrument [Line Items]
Credit available with FHLB	7,400,000,000
Credit with FHLB utilized	$ 2,000,000,000.0
Minimum [Member] \| FHLB [Member]
Debt Instrument [Line Items]
Effective interest rates	1.62%		1.11%
Maximum [Member] \| FHLB [Member]
Debt Instrument [Line Items]
Effective interest rates	4.19%		4.19%
Subordinated Notes Due 2029 [Member]
Debt Instrument [Line Items]
Long-term borrowings, face amount	$ 120,000,000.0
Proceeds from debt, net of issuance costs	118,200,000
Trust Preferred Securities [Member] \| American Community Capital Trust I [Member]
Debt Instrument [Line Items]
Redeemed amount	$ 10,000,000.0