Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Derivative Instruments and Hedging Activities - Derivatives Designated as Hedging Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income (loss)	$ (168)	$ 212
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	18,216		$ 18,422
Derivative Assets	24		189
Derivative Liabilities	4		0
Net loss	17	(20)
Gain (loss) recognized in other comprehensive income (loss)	19		80
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	16,881		17,076
Gain (loss) recognized in other comprehensive income (loss)	19		80
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net loss	(16)	20
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets	24		185
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liabilities	0		0
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional Amount	1,335		1,346
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Fair Value Hedging [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net loss	1	$ 0
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Fair Value Hedging [Member] \| Other Assets [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Assets	0		4
Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Fair Value Hedging [Member] \| Other Liabilities [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Liabilities	$ 4		$ 0